-

UNIVERSITY OF MARYLAND "'C

~ MARYLAND AGRICULTURAL EXPERIMENT STATION f COLLEGE PARK - EASTERN SHORE - RESEARCH FARMS

Sterile Acceptable Milk (SAM) :

A Major Energy Saving Technology

Summary and Recommendations

MP 959

October 1980

Contribution number 5921 and miscellaneous publication number 959 of the Maryland Agricultural Experiment Station, Director's Office.

The University of Maryland is an equal opportunity inst~tution with respect to both education and employment. The university's policies, programs and activities are in conformance with pertinent federal and state laws and regulations on nondiscrimination regarding race, color, religion, age, national origin, sex and handicap. Inquiries regarding compliance with Title VI of the Civil Rights Act of 1964 as amended; Title IX of the 1972 Education Amendments; Section 504 of the Rehabilitation Act of 1973; or related legal requirements should be directed to Dr. Robert S. Beale, Sr., Assistant to the Provost for Affirmative Action, Symons Hall, University of Maryland, College Park, MD 20742. Tel. 301/454-5981.

T able of Contents

Preface . .

Background

Milk Sanitation and Preservation

The Role of Pasteurization and Refrigeration Purpose of Pasteurization . Current Legal Requirements Current Industry Practice . The Need for Refrigeration Shelf Life Product Losses

Alternatives to Pasteurized Milk--Sterile Milk

Existing Sterile Milk Systems In Bottle Sterilization . . . UHT Sterilization . . . . . . Flavor of Conventional L~T Milk Nutritive Value of UHT Milk . . Sterile Milk in Europe, Canada, and the U.S.

DASI Steam Infusion Processed Milk

Summary and Recommendations

Economic Considerations Regulations . . . . . Legal Considerations

References

2

6

9 9 9

11 11 11 12

13

13 14 15 16 17

, 17

. 20

28

32 35

• 36

37

Table 1:

Table 2:

Table 3:

Table 4:

Table 5:

Table 6:

Table 7:

Table 8:

Table 9:

Tables

Fluid milk products per ca pita consumption in U.S ..

Per Capita U.S. consumption of orange juice, coffee, tea, soft drinks and fluid milk

Current minimum pasteurization standards

Flavor evaluations of milk stored in rosin paperboard cartons

Flavor evaluations of milk stored in rosin paperboard cartons foil-lined

Flavor evaluations for cyanasize juice paperboard con tainers . . .

Flavor evaluations of cyanasize paperboa rd foil-lined containers . .

Dairy Marketing Forum--Taste test results

SAH estimates of annual energy savings .

Table 10: Estimates of total market for fluid milk project SAN, production levels and resulting energy savings .

6

7

.... 10

... 24

. • 25

. . . 26

. . . . . 27

28

29

. .... 31

Figures

Figure 1 : Sam project organizational chart 3

Figure 2 : Number of milk processing plants [)

Figure 3 : Temperature-time curve for HTST process 22

Figure 4: Temperature-time curve for DASI process 23

Figure 5: Projected market penetration of SAM 30

Figure 6 : Cumulative SAM estimates for the most likely case 33

Figure 7 : Accelera tion of adoption of SAlf due to phase II demonstration . . . . . . . . . . . . . . . 34

Study Team

University of Maryland

Dr. Lamar Harris Project Principal Investigator

Dr. Filmore E. Bender Principal Investigator Economics

Dr. Richard F. Davis Principal Investigator Aseptic Packaging System

Dr. Barry C. Frey Principal Investigator Agricultural Engineering

DASI Industries, Inc.

Dr. John Nahra Principal Investigator

Exotech Research and Analysis, Inc.

Mr. Libert Ehrman Principal Investigator

Mr. Foroud Jahandari Engineering Analyst

Mr. Robert P. Wolfson Project Engineer

Dr. Joseph M. Mattick Principal Investigator Dairy Science

Dr. Allen Prindle Investigator Economics

Dr. Larry E. Stewart Project Director

Dr. Dennis C. Westhoff Principal Investigator Microbiology

Mr. Walter Woods Investigator

Ms. Megaera Ausman Research Analyst

Ms. Seale George Research Analyst

Preface

This study provided a technical assessment of the feasibility of introducing sterile acceptable milk (SAM) into the American economy and the energy and economic impacts that would result from such an innovation. This research was viewed as Phase I of a total program of research, development and demonstration. Phase II would provide the essential demonstration required to introduce successfully sterilized milk as a major part of the American diet.

This bulletin provides an overview of the research project and highlights of the analysis.

Participants in the SAM Project

Phase I of the SAM project was carried out by personnel of the University of Maryland and its subcontractors, DASI Industries, Inc., and Exotech Research & Analysis, Inc., (ER&A). University investigators had primary resp<;msibility for the chemical, physical, microbiological, nutritional and enzymatic research. DASI Industries engineers worked with the University in engineering and designing the milk processing system while also preparing operational data on the DASI sterilizer. ER&A investigators had primary responsibility for collecting, analyzing and evaluating data on energy consumption for both conventional and SAM processing systems; they also coordinated economic studies with University researchers. Computer services for the University's report were provided through the facilities of the Computer Science Center of the University of Maryland.

Project Management

Figure 1 illustrates the major areas of responsibilities and the reporting relationships for the major University of Maryland, DASI and ER&A participants.

(1) Mr . Larry Kelso replaced Dr. D. R. Price as the DOE technical administrator.

(2) INEL Project Director W. Paul Jensen had administrative responsibilities as provided by DOE.

(3) Project Principal Investigator Dr. W. Lamar Harris was responsible for defining major objectives; assigning responsibilities to the University of Maryland Project Director, Scientific Principal Investigators and subcontractors; allocating contract and University of Maryland resources to the project; monitoring project performance; establishing and maintaining relationships with the Project Review Panel; chairing Panel meetings; and providing liaison with DOE and INEL.

(4) Project Director Dr. Larry Stewart was responsible for coordinating the definition of project tasks in conjunction with the principal investigators and subcontractors; coordinating project work plans, priority, and

2

Department of Ener gy

Jechn i cal Administrator

L. Kelso

Project Principal In ve s tigator IHEl

Project Review ~

Project Director Pa ne 1 --- W. P . JENSEN

".1... HARR IS

w

I Project Dire ctor Projec t Engineer

Offi ce of ER&A Cont ra cts & Grants L . C. STE WA RT

R.t>. WOLfSON

I I 1 J I I Principal Princi pa l Prin ci pa l Principal Pr i ncipal Pr;ncip.l Prin c ipal

I nvestigator In vestigator Investigato r Inve s tigator Investigator Inve st igat o r I nv e s t; ga tor

Asepti c Pa c k.aged I - Oairy Scien ce Agricultural SI PH Technolog y ........ Mi crobiolo gy - Energy Studies - Econom ics Produ c ts ~ En ginee r ing - DASI and Repo rt s

ER&A I

R .T. DA VIS J . ,. . IfA TTI C K I B. C. FReY J. t:. NAH RA D. C . WESTHOFF L . EHRIfAN r.E . SENDER I -

Figure 1 Sterile Acceptable Milk (SAM) Project Organization Chart

scheduling of . project tasks; coordinating and managing project expenditures; and defining and distributing project documentation.

(5) Each Scientific Principal Investigator had primary responsibility for a specific technical area as well as for coordination with the Project Directors and other Principal Investigators:

a. Dr. R. F. Davis for obtaining aseptic packaging equipment necessary to complete a pilot SAM system.

b. Dr. J. F. Mattick for assisting Dr. B. C. Frey in the design and installation of the pilot plant and for operating the pilot plant.

c. Dr. B. C. Frey for the design, installation, and instrumentation of the pilot plant, including the aseptic packaging, in coordination with Dr. Mattick, Dr. Davis, and Dr. Nahra.

d. Dr. J. Nahra (DASI) for the engineering analysis and operational energy data for the DASI sterilizer as well as optimized models for all related subsystems.

e. Dr. D. C. Westhoff for carrying out the necessary research and data development to evaluate product sterility and to meet requirements for product approvals by regulatory agencies .

f. L. Ehrman (ER&A) for energy studies, including data collection, modeling, assessment of impediments to introduction of SAM products, and preparation of reports in coordination with other Scientific Principal Investigators. In addition to working on ER&A's energy studies, R. Wolfson provided the Project. Director with staff support in planning, scheduling, and systems engineering.

g. Dr. F. E. Bender for defining the character of the economiC studies and performing the necessary work to carry them out.

Project Review Panel

A Project Review Panel was established to provide the Project Staff with program guidance and technical advice and to ensure the involvement of representatives whose reactions are important to the introduction of sterile milk in the United States. The members of the panel were as follows:

Dr. John B. Adams, Director, Environmental and Food Regulatory Affairs, National Milk Producers Federation

Dr. J. A. Alford, Chief, Dairy Foods Nutrition Laboratory, Beltsville Agricultural Research Center

Mr. Alan C. Bennett (guest), Food Technology Division, Animal Products Group, Food Engineering Laboratory, U.S. Army Research & Development Center

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Mr. H.S. Christiansen, Director of Environmental Control, Carnation Company

Mrs. Alice T. Davis, National Council of Negro Women

Dr. Earle E. Gavett, Economic Research Service, u.S. Department of Agriculture

Dr. M. Glickstein, Food Technology Division, Animal Products Groups, Food Engineering Laboratory, u.S. Army Research & Development Center

Mrs. Bettye Gray, Consumer

Mr. W. Paul Jensen (observer), Manager, Energy Conservation Programs, EG&G Idaho, Inc.

Dr. C. J. Mackson, Director, School of Packaging, Michigan State University

Dr. Martin Okos, Assistant Professor, Department of Agricultural Engineering, Purdue University

Dr. D. R. Price (observer), Agriculture and Food Process Industries Branch, Division of Industrial Energy Conservation, DOE

Mr. W. Jasper Reaves, Vice President for Product Development, Dairy Research, Inc.

Mr. Emmett Rice, Senior Vice President, National Bank of Washington

Dr. William N. Roberts, Professor, Department of Food Science, North Carolina State University at Raleigh

Dr. Benjamin Schneider, Professor, Department of Psychology~ University of Maryland

Mr. Glenn P. Witte, Administrative Assistant, Milk Industry Foundation

Significant Results

It was determined that a sterilized milk can be produced that compares favorably with pasteurized milk for flavor. In addition, it was determined that the introduction of sterilized milk would save the equivalent of 185 million barrels of oil by the year 2000 if industry adoption would begin as early as 1983.

It was estimated that the introduction of sterilized milk would result in nonenergy savings valued at $4.7 billion and energy savings worth $1.7 billion. These savings would be accomplished with minimal changes in the marketing system and with slightly less capital investment than that required by conventional technology.

The primary barriers to widespread adoption at this time appear to be existing regulatory obstacles and the lack of a commercial scale demonstration. Such a commercial scale demonstration would be necessary to demonstrate the ability to package sterilized milk in the variety of package sizes and types

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required to service all fluid milk markets; the ability to maintain such sterility; and the consumer acceptance of such a product.

Complete results are reported in Harris et al . Sterile Acceptable Milk (SAM) Phase One Final Report, DOE Contract EC77-5-07-1689.

Volume I: Volume II: Volume III:

Technical Feasibility Energy Studies Inputs to DOE/Conservation-Project Evaluation System

Background

Fluid milk is a maJor food item for United States consumers: when measured by weight, it accounts for more than 15 percent of all food consumed in the U.S. Furthermore, fluid milk provides more than 12 percent of the protein and 40 percent of the calcium in the American diet. Although this report focuses attention on fluid milk, it represents less than 45 percent of all milk and milk products in the U.S. diet.

Many interacting forces have been responsible for the complex nature of the milk and dairy products industry in the United States, an industry that in 1979 accounted for 14 percent of the 200 billion dollars spent on food. Through the 1950's--with higher incomes and relatively higher birth rates--per capita demand kept pace with increased production. More recently, however, while total fluid milk production has been increasing, per capita consumption has been decreasing; from 321 product pounds in 1960, it was down to 289 pounds in 1977 (Table 1).

Year

1955 1960 1965 1970 1975 1977

Table 1

Fluid milk products: per capita civilian consumption United States, selected years

Fluid Products a

348 322 302 264 M6 243

Product Weight (milk)

321 311 296 291 289

aMilk equivalent (fat solids basis) of whole milk, cream items, and skim milk.

While per capita consumption of fluid milk has been declining, per capita consumption of orange juice, coffee, tea, and soft drinks has been increasing (Table 2). For example, since 1960, orange JUlce consumption almost doubled while soft drink consumption more than doubled.

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Table 2

Per capita u.s. consumption of orange juice, coffee, tea soft drinks and fluid milk for selected years, 1955-1976

Oran&e Coffeeb Fluid Milk Year Juice a Instant/Regular Teac Soft Drinksd and creame

1955 4.08 0.5 11.2 0.6 NA 344

1960 4.43 0.8 10.8 0.6 13.6 321

1965 4.00 0.8 10.4 0.7 19.2 311

1970 5.85 0.7 9.8 0.7 24.1 296

1975 7.89 0.9 8.1 0.8 27.6 291

1977 8 . 78 0.9 8.5 0.8 31.0 292

aproduct weight, pounds

bRetail weight, pounds

cLeaf equivalent basis, pounds

dGallons

eFluid milk and cream, product weight, pounds

Sterilization, pasteurization and boiling preserve the nutrient quality of milk and extend its shelf life. Although all of these forms of heat treatments produce some denaturation of proteins, the denaturation of milk proteins does not alter their nutritive value.

Milk is an especially important source of protein, calcium, phosphorus, B vitamins, niacin, and riboflavin. Except for the proteins in eggs, the chief proteins in milk, casein and lactalbumin, are the most efficient for promoting growth. Tryptophan and lysine are the amino acids in milk proteins that supplement well the protein value of cereals and breads which lack these essential amino acids. Moreover, milk is a relatively economic form of protein. Although cereals and dried legumes furnish proteins at a lower cost, they are of lower nutritive value than milk (or eggs). While milk could significantly alleviate the nutritional protein shortages facing some people in the United States as well as those in other areas of the world, its contribution (with dairy products) to total protein has been declining steadily since the 1950's.

Consumers are highly conscious of the taste of milk. As one of the more perishable items stored in the kitchen, milk often determines how many trips must be made to the store during the week. The relatively high temperature of fluid dairy products in store coolers, dairy cases, and home refrigerators reduces the

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shelf life. Immediately following processing, the temperature must remain below 40 0 F for maximum shelf life; generally for every 5 0 F rise in temperature, shelf life is reduced by 50 percent. That is, milk refrigerated at 40 0 F should have a shelf life of 10 days; at 45 0 F that shelf life will go down to 5 days.

As shown by Manchester (1978), the fluid milk industry has for many years b een characterized by a continuing decline in the total number of plants and a continuing shift to newer and larger plants. Figure 2 shows the decline In the number of plants over time. Since total volume has continued to Increase, average plant size has also increased .

While the fluid milk industry still consists of a large number of widely distributed plants, the number of small, older plants has been declining with replacement by fewer, larger plants.

THOUSAND PLANTS 10

8

4

2

o~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

1950 55 60 65 70 75 80

SOU RC E: U.S. Department of Agriculture, Dairy Price Policy: Setting, Problems, Alternatives. Report No. 402 . 1978 , Page 4.

Figure 2: Number of Milk Processing Plants

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Milk Sanitation and Preservation

The Role of Pasteurization and Refrigeration

Spoilage is due to the growth of certain forms of widely distributed microorganisms. They are in the soil, in the water, in the air, and on all surfaces with which they come in contact. Because of their wide distribution, all food products, as they occur naturally, become contaminated with them.

Purpose of Pasteurization

Long before Pasteur, and long before any understanding of pathogenic micro­organisms, milk was being heated to increase its shelf life. As C. W. Hall and G. M. Trout observe, "housewives had resorted to cooking or boiling milk for ages, and such practices still exist where pasteurized milk is not available." After Pasteur demonstrated the role of microorganisms in causing undesirable changes in food, the importance of heating as a means for killing microorganisms became widely understood. Some recognized heating as a way for increasing its shelf life or at least making milk somewhat more stable over a period of time.

Prior to 1900, several milk-borne diseases were identified, among them, typhoid fever, diptheria, scarlet fever, tuberculosis, anthrax, and foot and mouth disease. By the turn of the century, many investigators accepted the effectiveness of heat treatments (7l 0 c or less) to destroy pathogenic microorganisms.

Current Legal Requirements

Table 3 details the current minimum time-heating standards for var~ous pasteurization methods.

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Table J

Current m~n~mum pasteurization standards

Methods and Product Time-Temperature

Vat or batch pasteurization

Milk

Cream

Ice Cream Mix

HTST - pasteurizationa

Milk

Cream

Ice Cream Mix

UHT - pasteurizationb

All Products 1.0 sec - 191°F (88.JoC)

0.5 sec - 194°F (90 . 0 0 C)

0.1 sec - 201°F (9J.90C)

0.05 sec - 204°F (95.6°C)

0.01 sec - 212°F ( 100°C)

Ultra-pasteurized All Products 2 sec - 280°F (lJ7.80C)

aHTST is the common abbreviation for High Temperature Short Time pasteurization.

bUHT is the common abbreviation for Ultra High Temperature pasteurization.

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Current Industry Practice

Vat or batch pasteurization is very limited in the United States. Plate heat exchangers are the most widespread means for satisfying the high temperature, short time pasteurization requirement of l6l oF for at least 15 seconds. This continuous flow technique is compatible with industrial practices. Most dairy processors realize that when they increase temperatures, or when they increase holding time above the legal minimum, they will reduce the microbial population considerably. For this reason many dairies are processing at times and temperatures above the legal minimum. It is not unusual to find processing temperatures of l70 0 F or above, for 20 to 25 seconds, from which a further benefit also results--increased refrigerated shelf life.

The Need for Refrigeration

For both microbial and legal reasons, refrigeration is mandatory for all vat, UHT, and HTST pasteurized products. None of the pasteurized processes--vat, HTST, and UHT--is a sterilization technique. Therefore, following heat treatment at any of these times and temperatures, the milk will still have surviving microorganisms. If unrefrigerated, it will spoil in a short time. Unlike sterilized milk, this is so for all pasteurized products.

In some instances, ultra pasteurized products, which are processed at temperatures in excess of 2800 F for at least 2 seconds, might be effectively sterilized. However, the time-temperature combination for ultra pasteurized products could not always be depended on for safe sterilization. Therefore, immediately after heating, ultra-pasteurized products, like all the milk and milk products listed in Table 3, · must be cooled to 7.2 0 C and maintained at that temperature.

Shelf Life

Of major concern to regulatory agencies, milk processors, and consumers is the shelf life of fluid milk products. Pasteurized milk is a safe product; however, it is vulnerable to spoilage because of the residual bacteria that are present in milk even after pasteurization. Internal quality control personnel are constantly evaluating the shelf life of the products produced. Such evaluations are performed under "ideal" control conditions and the results ob­tained normally show the shelf life of fluid milk to be approximately 20 days. In these in-house evaluations, storage temperatures in the 35 0 to 40 0 F range are used. Unfortunately, such evaluations are not true indications of the shelf life, since the shelf life expectancy for the same milk sampled from retail outlets is significantly reduced. The regulatory agencies are fully aware of this shelf life problem and have established various "sell-by-date" regulations such as 4 days (New York), 9 days (Pennsylvania) and variable number of days (California and Maryland - sell-by-date based on quality history of each milk processor). The guideline for establishing the sell-by-date by each regulatory agency is based on its best projection to have a milk that is consumer acceptable for at least 7 days after the sell-by-date.

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The shelf life of pasteurized milk is therefore dependent on (1) residual bacteria of the psychrotrophic type in milk and (2) product storage temperature. Most psychrotrophic or spoilage type bacteria are capable of comparatively rapid growth at temperatures above 500 F, moderate growth at 46-50 0 F, slow growth at 4l-45 0 F, and much slower growth at temperatures below 40 0 F. In any discussion of fluid milk shelf life, both bacterial type and numbers and product storage temperature must be considered . Since the number of bacteria are usually rather low, temperature control during storage is generally considered to be the key to extended shelf life of fluid milk. A common rule of thumb is this: "For each 50 F increase in storage temperature, the expected shelf life of the product can be reduced by one-half." Stated in shelf life days expectancy, a storage temperature of 35 0 F should provide 20 days shelf life, 4loF should provide 10 days, and 45 0 F, only 5 days shelf life. To sum up, to achieve an acceptable shelf life, pasteurized milk must have both low total and psychro­trophic counts while maintaining refrigerated storage temperature of 400 F from processing plant to home refrigeration systems.

Approximately 85% of all milk sales in the U.S. occur through retail food stores. Consequently, one might expect that it is in these outlets where most of the shelf life reduction occurs. Research by the University of Maryland has shown that retail stores and processors in the state appear to have an excellent record. The results from examination of 4417 cartons of milk picked up at retail, and representing all milk processors in the state, showed that 65 percent were less than two days past the date of pasteurization. Additionally, the average temperature of the milk display cases was 7.l oC (44.7 0 F). This indicated a high rate of turnover and a good keeping temperature for the products.

There is no doubt that reduced shelf life and spoilage of milk is serious. It is difficult, however, to determine the magnitude of the problem since milk spoilage information from processors is not available. Emphasis is always given to the in-house, highly controlled shelf life data. Surveys made by independent consumer-oriented groups estimate that for each product spoilage complaint made to a processor or retail outlet, there are 40 instances of product spoilage failures that are not reported. Studies have shown that bacteria growth is the major causative agent for shelf life failures and that failure to maintain low refrigerated storage temperatures is the extrinsic factor responsible. The reasons for product failures are known; however, the constant controls required to maintain product quality in all phases of the processing, distribution, and especially sales of milk, have not been realized. There is a reason for each instance of product spoilage. With the existing system of quality control, spoilage must occur before the causes can be determined. Attempts to control the handling of milk in the retail outlets have not been successful.

Product Losses

Product losses, whether spoilage or returns, have always been serious problems for milk processors. Because of the lack of dependable or meaningful data from the processors, statements about such losses must be based on assumptions and estimations. Most processing organizations state that product returns and spoilage are minimal since the stocking of fluid milk products in retail outlets is based on the sales volume history of each outlet. In addition

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to controlled stocking, fluid milk is merchandised on a first in - first out (F.I.F.O.) basis using the sell-by-date as the criterion for product movement.

From a production viewpoint, it is estimated that every loss of 1 gallon of milk (excluding the cost of the milk) results in an average production loss of 8 cents. At the present time, raw milk is priced at approximately $13.00 per 100 pounds. At 1 percent, an additional 13 cents for each pound of milk lost would result.

In the evaluation of product losses, all facets of an operation, from farm to consumer, must be considered. It is not accurate to consider only the losses that occur in the final product form. A loss at any point in the over-all operation affects operational efficiency. The greatest loss, however, results when a finished product is rejected since this product has received the maximum cost input with a minimum, if any, salveagable value. Based on total fluid milk sales of approximately 60 billion pounds per year and an average 2 percent point-of-sale loss, 1.2 billion pounds of milk are lost annually in the u.s. because of spoilage and being out of date. This estimate does not include the losses in home spoilage. In addition to milk losses, production, processing, packaging, distribution, and storage costs would increase the total monetary losses appreciably.

Alternatives to Pasteurized Milk--Sterile Milk

Existing Sterile Milk Systems

Although technical and legal definitions vary considerably, it is generally agreed that steri~e milk must "keep" unrefrigerated for a prolonged time without deterioration, must be free from harmful toxins and organisms and must be free from microorganisms which can grow in milk and contribute to its deterioration.

Sterile milk has been produced in the United States and Europe for more than 70 years. While conventional high temperature sterile processing systems destroy bacteria, there is an inherent limitation on turbulence or agitation during processing. Studies at the U.S. Department of Agriculture (USDA) Dairy Products Laboratory and in Europe indicated that physical stress will cause structural deformation of individual milk particles. This results in product instability during storage and chalky or sandy off-flavors.

Considering the exigencies of physical stress and time/temperature parameters, four basic criteria can be set, theoretically, for an ideal sterilization system:

* Instantaneous rise to ultra high temperatures (approaching) 00;

* Holding time approaching zero, with instantaneous return to original temperature;

* Uniformity--each and every particle exposed to exactly the same conditions;

* No physical stress on individual par­ticles at high temperatures.

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This ideal system would produce a milk with exactly constant flavor and food value, zero bacteria count, and no chemical or physical particle damage. However, a system to meet these specifications cannot operate in the real world. Temperature changes occur over a span of time, no matter how short; absolute uniformity cannot be achieved in an ongoing process, and some physical stress must always occur if there is motion.

What needs to be determined instead are the criteria for a commercially ideal system that is physically practical. Taking into consideration theoretical criteria and the requirements of commercial usage, ten factors seem to be most important:

(1) Fast and efficient heat transfer

(2) Capability of heating large volumes to ultra high temperatures

(3) Accurate control of heating, holding, and cooling times.

(4) Uniform conditions for all particles

(5) Minimal physical stress at high temperatures

(6) Ldng running time

(7) Efficient use of energy

(8) Mechanical simplicity (diminishing downtime and minimizing cost)

(9) Constant product quality with minimal nutritional losses

(10) Good flavor (no off or cooked flavor)

There are essentially two approaches for heat sterilization of fluid milk: in-bottle sterilization and Ultra-High-Temperature (UHT) sterilization .

In -Bottle Sterilization

In-bottle sterilization is the heating of a sealed milk package after it has been filled. Various methods have been used in packaging (can, bottle) and heating (steam, air). Various heating rates and amounts of preheating of the fluid milk before filling have been tried. The most widely known dairy product of in-bottle sterilization in the United States is evaporated milk .

Two inherent problems exist using in-bottle sterilization. The first is the burn-on deposits on the container walls; the second is relatively long times (minutes) necessary to raise the temperature of the milk particles. Low sterilization temperatures are thus used, necessitating long holding times. Chemical reactions and physical changes have a relatively long time to take

14

place, causing adverse effects on the physical and nutritional properties of the milk. Most COmmon among these are: cooked flavor, burn-on* smear-on**, gelation, sedimentation, and coloring. The probability of greatly improving the physical properties of evaporated milk or sterile milk by variations in the conventional in-bottle sterilization process is not very high. This is because the heat transfer mechanism is inefficient and far from the ideal system.

In-bottle sterile milk had a substantial share of the fluid milk market ~n Europe and other countries before the introduction of UHT milk.

UHT Sterilization

There are essentially two conventional approaches for UHT sterilization of fluid milk: (1) indirect heating where heat is transferred from a heating medium through a metal surface to the milk; (2) direct methods where heat is transferred directly from the heating medium to the milk. Saturated steam is used as the heating medium and is mixed turbulently under pressure with the milk. Both direct and indirect methods have been used in the United States and Europe.

Indirect Methods

There are generally two types of UHT processing systems that use indirect heating--those with tubular heat exchangers and those with plate heat ex­changers.

Tubular Method

Narrow diameter tubes are heated to high temperatures, and the milk is heated by conduction as it passes through these tubes. While the efficiency of heat transfer is better than with either the batch or in-bottle methods, the uniformity of heat treatment is still poor. Turbulence, which is needed for efficient heat transfer as the milk is forced through the tubes, means increased physical stress on the milk particles at high temperatures. Both running time and flavor are affected because of the build-up of milk on overheated metal surfaces; blockage of the tubes and cooked flavor usually result. Product quality necessarily varies from beginning to end of a run as the result of burning on and the subsequent loss of heat transfer efficiency. A number of UHT systems using this method are now in operation in the U.S. and Europe.

Plate Method

Corrugated plates are used in this system. The plate heat exchanger has an even greater heat transfer surface area/volume ratio than the tubular method as the milk flows over plates which are heated from the reverse side by either

*Burn-on is the deposition of milk solids adhering to the package walls.

**Smear-on is a thin coating of coagulated protein spread uniformly over the package walls.

15

steam or hot water. Accuracy of controls is proportionately better. Heat transfer, UHT capability, uniformity, product quality, and flavor are approximately the same as with the tubular method; build-up on overheated metal surfaces occurs in this method as well. Running time is limited because of blockage by surface deposits, but to a lesser degree than in the tubular methods, since a greater build-up is needed to cause system blockage with plates than with narrow diameter tubes. A number of UHT plate systems are now in use in the U.S. and Europe.

Direct Methods

Direct methods heat milk to sterilizing temperatures by directly adding purified (culinary) steam to the milk. Two conventional methods of direct heating are steam injection and steam infusion.

Steam Injection

In steam injection UHT systems, the milk is heated to sterilizing temperatures by injecting steam under high pressure directly into a pipe containing flowing milk, thus creating a large amount of turbulence and mixing action. The heat transfer mechanism, in this case, is largely due to forced convection and heat condensation from the steam. Large pressure and temperature gradients and heat transfer differences are the result. Experiments have determined that turbulence and agitation at high temperatures are harmful to milk particles and result in milk instability during storage and sandy or chalky flavor in the milk.

A number of direct injection UHT systems are now ~n use ~n the U.S. and Europe.

Stearn Infusion

In steam infusion UHT systems, milk is forced into a pressurized atmosphere of saturated steam. The steam and the milk are mixed in a chamber. If milk particles contact the hot metal surfaces of the chamber walls, burn-on results. A limited number of these systems are in use in the U.S. and Europe.

Flavor of Conventional UHT Milk

It is widely accepted that UHT Milk using conventional methods has a flavor and appearance much closer to pasteurized milk than to in-bottle sterile milk. Still, there remain significant flavor defects in UHT milk, When compared with pasteurized milk, which have been characterized as cooked, burned, and sandy (or chalky).

All UHT systems produce some cooked flavor in the sterilized milk. Cooked flavor results from the denaturation of whey proteins which produce sulfydryl compounds. The severity of the heat treatment determines the amount of denaturation and therefore, the cooked flavor. Protein denaturation begins when milk is heated above 16SoF (7S 0 C). In sterilized milk, the sulfydryl com­~ounds are oxidized with the presence of oxygen and eventually the cooked flavor

16

is reduced or disappears. This depends on many factors, among them the amount of SH groups, the amount of oxygen present in the container, the storage temperature, and the porocity of the container.

Burnt flavor results from the burn-on of milk on hot metal surfaces. The burnt flavor does not dissipate in storage as is the case with cooked flavor. Burnt flavor is most severe in indirect UHT systems where the milk is heated to sterilizing temperatures via a metal surface. Moreover, the amount of burnt flavor can vary significantly, from the beginning to the end of a production run, due to the build-up of milk solids on heating surfaces.

Sandy or chalky flavor, perhaps the most important and least understood, results from high turbulence and stress on milk particles. This defect is also manifested by instability of the sterilized milk during storage. Protein agglomeration results in sedimentation and oiling off, that is, separation of milk solid particles to the bottom and top of the container respectively during storage.

Scientists at the USDA Dairy Products Laboratory found a direct relationship between the amount of sediment on storage and the amount of turbulence at sterilizing temperatures in producing sterilized milk concentrates.

Steam injection UHT systems perhaps produce the greatest amount of turbulence and stress on milk particles at sterilizing temperatures. A study at the University of Wisconsin sponsored by United States Steel concluded, "Direct steam injection sterilizing proved to be unsatisfactory ..... Chalky flavor defect and sedimentation problems during storage ..... were typical of direct steam sterilization of milk concentrates." The same instability and flavor problems occur in single strength UHT milk but to a lesser extent.

Nutritive Value of UHT Milk

UHT sterilization is significantly less severe than in-bottle (retort) sterilization and more severe than pasteurization. There is now a considerable body of evidence, particularly from Europe, to show that conventional UHT processing is a conservative form of heat treatment causing little loss of nutritive value. During subsequent storage in light-proof containers impermeable to oxygen, UHT milk retains almost all of its nutritional merit. The only important changes in the content of nutrients are the inevitable losses of Vitamin B6 and Vitamin B12, and the losses of ascorbic and folic acid that occur unless the oxygen content of the milk is reduced to around 1 ppm before or during processing.

Sterile Milk in Europe, Canada, and the United States

European Experience

With the advent of economical aseptic packaging systems, UHT milk was commercially introduced, first, in Switzerland in 1961, and then in other European countries where its share of the market has grown rapidly. Many complex, and often unique, factors affect market penetration of UHT milk. UHT milk presently accounts for about 35 percent of packaged fluid milk in

17

"continental" Western Europe and is growing at the rate of 35 percent per year. Continental Europe excludes Scandinavian countries and the United Kingdom, In these countries, the pasteurized milk industry has successfully resisted large-scale incursions of UHT sterilized milk. Almost 90 percent of all fluid milk is still distributed door-to-door in returnable bottles. Moreover, in sophisticated dairy countries, resistance to the taste of UHT milk is the most important factor limiting its growth.

The market share varies widely between European countries, ranging from more than 50 percent in Italy and West Germany to less than 5 percent in the Netherlands.

Italy undertook the earliest development of large-scale aseptic packaging. West Germany and France are the other major aseptic packers, partly because the total markets are large, but also because in the smaller countries distribution problems are less severe.

The long storage life of UHT milk at room temperature initially displaced in-bottle sterilized milk, which was widely used, and also increased the total consumption of fluid milk products.

In most European countries, UHT milk sells at a premium over pasteurized milk since pasteurized milk prices are controlled and in some cases subsidized by the government. In Germany, however, URT milk is discounted at approximately 15 to 20 percent from pasteurized milk.

Although the main factors affecting the marketing of unrefrigerated UHT milk apply to Europe, they may also have applicability to the United States and other parts of the ~vorld. Among these factors are the following:

0) The decline of door-to-door deliveries.

(2) The . .

of the supermarkets. increasing power

(3) The increasing power of the dairy farmer cooperatives.

(4) The distance between milk production areas and big consumption areas.

(5) Production efficiencies--less manual handling involved with aseptic products; improved and more mechanized storage systems; and plant op­eration schedules which avoid overtime labor and surge overloads.

(6) Energy savings--elimination of the need for costly refrigeration in storage and trans­port to customers.

(7) Improved distribution--difficulty of retail shops in stocking enough conventional refrig­erated milk products for peak shopping on Fridays and Saturdays.

18

Canadian Experience

(8) The desire of major dairies to extend their markets geographically and optimize their distribution.

(9) The trend to once-a-week, one-stop shopping.

(10) Government regulations controlling pasteurized milk.

(11) The potential for a significantly lower cost than with pasteurized milk.

(12) The widespread use of in-bottle sterile milk.

Commercial UHT fluid milk was introduced to North America in the fall, 1975, when Cite' Dairy in Quebec City, Canada, started to market 2 percent UHT milk. This project was heavily supported by the Canadian government with financial aid and other assistance. (A small independent dairy, Cite' Dairy was recently acquired by a large Quebec dairy cooperative.)

Sold under the trade name "Grand Pre", the product was initially introduced with large advertising support. It immediately penetrated the market, capturing 18 percent of the 2 percent milk market of Quebec City. Subsequently, the market share dropped to approximately 5 percent. At first, the product was sold in supermarkets at 3¢ a liter premium from pasteurized milk; later, the premium was increased to 6¢ per liter.

Currently, two additional UHT milk plants are In operation In Canada. One IS in Calgary, the other in Toronto.

A study by the Ontario Milk Marketing Board indicates that approximately one third of consumers bought Grand Pre as a replacement for other kinds of milk and two thirds in addition to other types. The use of UHT milk seems to be concentrated in the smaller households, although trial of the product was equal throughout the range of household sizes.

As to the flavor of the UHT milk, the Task Force states In its report summary the following:

"In the VIew of the Task Force, the flavor of the UHT milk presently being processed is not of a consistently high enough standard for it to be introduced into Ontario without consider­able risk to per capita consumption."

"About half the Quebec households consider UHT milk to be inferior in taste to their regular product. About two thirds of a very small Ontario sample of housewives complained about the taste

19

of the product, either from their own point of View or on behalf of their families reaction to it. "

"The flavor of the UHT milk in Europe varied con­siderably from there being very little difference from the flavor of pasteurized milk to being very obviously different from, and inferior to, pasteur­ized milk."

"The consistency of flavor of UHT milk is a per­sistent processing problem. This was evident in both Quebec and Europe. At best, UHT milk can only equal pasteurized milk in terms of taste, and where it differs from pasteurized milk it loses by com­parison."

Furthermore, the Task Force recommends that "UHT milk should not be introduced into the Ontario market until there is considerable improvement in the flavor properties of the product. The Task Force observed that there was a definite lack of consistency in the flavor of UHT milk in Quebec and in Europe."

United States Experience

Unrefrigerated UHT milk in flexible packages has not as yet been introduced in the United States. There are, however, nearly one hundred small UHT processing systems in the United States principally used to produce long life refrigerated creams and other dairy by-products. Nearly 50 percent of all cream products in the United States are now sterilized. However, they continue to be sold and held under refrigeration.

At least two plants are presently producing sterilized milk processed with conventional UHT systems. At one plant, the sterilized milk is aseptically packaged in paper containers and is sold refrigerated, mostly in Alaska. At the other plant, sterilized milk is aseptically packaged in metal cans and sold unrefrigerated .

DASI Steam Infusion Processed Milk

The patented DASI Free Falling Film Steam Infusion UHT method heats milk to sterilizing temperatures as it falls under the force of gravity in thin laminar films through free space in a saturated steam atmosphere, During the heating process, the milk does not make contact with any surface.

This sterilizing method has several important characteristics when compared with conventional UHT systems. The use of a thin, free falling film provides extremely efficient and fast heat transfer between the product and the heating medium and very uniform heating of the individual milk particles, without any agitation or turbulence. The lack of contact with hotter than product surfaces during the heating process eliminates product over-heating from burn-on and the fouling of heating surfaces .

20

The ideal sterilization system would instantaneously raise the temperature of every milk particle as high as possible, hold this temperature for a very short period of time, then instantaneously cool it to its original temperature. Such a process, if it were possible, would accomplish complete sterilization with the least amount of deleterious effect on the components of the milk.

Two major problems arise in implementing such a process; the first IS the need for a very rapid rate of heat transfer, and the second is the need for uniform conditions that the milk particles are subjected to. Milk particles cannot be heated instantaneously, and a finite amount of time is needed to raise and reduce their temperatures in the heating and cooling processes, respectively. The rate of heat transfer then limits the sterilizing temperature that can physically be reached within the time requirements. Whenever milk is heated ~ mass such as in-bottle, in-tube, or in turbulence, all milk particles are not treated equally; some reach much higher temperatures and holding times than others, causing an adverse effect on those milk particles.

The process tested in this study seems to overcome most of the difficulties which cause objectionable flavors. Figures 3 and 4 show the temperature-time profiles for standard pasteurization and the sterilization process used in this study.

Under a cooperative agreement with International Paper Co., scientists at the University of Maryland conducted a shel~ life study of DASI milk in paper containers. The study showed that this product, aseptically packaged in paper or glass containers stored at room temperature (68oF/20 0 C) for periods up to 8 weeks, had no significant taste difference when compared with fresh, pasteurized milk. The taste tests were performed using a trained panel of milk tasters. Tables 4-7 summarize the results of the more than 1500 flavor evaluations that were performed.

Table 4 summarizes the means and ranges of numerical flavor scores for sterilized milk stored in rosin paperboard cartons and glass bottles up to 9 weeks at 20 0 C as well as for pasteurized milk. The pasteurized milk was commercially processed and purchased just prior to the Taste Panel meeting each week and was, therefore, not stored. Tables 5-7 summarize data for other carton types. In each case, the scores for sterilized milk in glass bottles and nonstored pasteurized milk were compared. The milk stored in glass bottles was labeled as a "control", since part of the purpose of the experiment was to evaluate any off flavors paper cartons may have imparted to the milk. Sterilized milk in glass bottles was not expected to score perfectly (a value of 40), but rather would provide a basis for comparison. Fifteen hundred flavor evaluations of sterilized milk were made during this study. Only 9 samples received a score of 32 (unacceptable). Their frequency is clearly indicated in Tables 4 through 7 .

The Student's t-test at a 0.05 level of significance was used for computing the possible significant differences between scores. At this level, there are no significant differences in any of the carton types or glass bottles for milk at week 0 through milk stored up to 9 weeks at 20oC. The wide range of scores, however, would mini~ize the significant differences; interestingly, scores for commercial pasteurized milk (not stored) varied also (Tables 4-7). Compared with taste scores for pasteurized milk, taste scores for sterilized

21

-U. 0 -W Q:

~ .-<I a::: W

N Q.. N

~ W .-

250

~ M ea sured T e mp . • 200

~ ,- Homogen i zer

~- ..... 165 0 F, HOLDING .TUBE

150

<l> ..0

::::I

100 ~

O"l C

-0 r... r- o-0 +-l O"l r cu c r....,-

5 0 ~ ClJr- ""'-- - Surge Vl c 0 T Regenera t or ~ ClJO Tank r O"lU ClJ- r...

(Heating) 0:: ClJ

0 0 u • I • • I • I I •

0 0 50 tOO 150 200 250 300

TIME ( SECONDS )

Figure 3: Temperature-Time Curve for the HTST Milk Processing System in Turner Laboratory, University of Maryland (at 600 GPH)

300

250 Sterilizer _______

(

Sterilizer Cone

~Holding Tube, ~ 285°F

6. Measured Temp.

200 Homogenizer I' FI h Ch b _ ) ____ as am er

~ 165°F

~ ~ ~ /Removal Pump

.a 150 Stuffing ~ Pump

N Q; ~ w 0-

~ 100~ / II ~ I-

~ SIFFF ~ ~ ~ Process .£ _ I I \. Surge <I> 0 CI:l Cl "- Tank ~ J: Q) .= 50 ~ Regenerator I <I> I- c: (5

(Heating) ~ ~ ~8 Q) ~ J: <1>- -~ ~ 0

/~ I 8 Booster Pump 0

o 50 1 00 150 200 250 300

Time (Seconds)

Figure 4: Temperature-Time Curve for CAS I Milk Processing in Turner Laboratory

milk, stored at 20 0 C for up to 8 weeks in any type carton or glass bottle, have (at the 0.05 level) no significant differences.

Weeks at

0

1

2

3

4

6

8

9

Table 4

Flavor evaluations l of milk stored in rosin paperboard cartons

Rosin Cartons

x Range

38.1 36-40

39.0 36-40

37.4 35.5-40

38.4 34-40

37.7 35-40

36.7 34.5-39

38.2 35-40

37.2 32-39(1)3

Contro1 2

x Range

37.2 32-40(1)3

36.2 33-38

37.5 36-38

37.4 34-39

38.2 37-39

38.0 35-39

37.4 36-39

37.8 36-40

Pasteurized Milk (Not Stored)

x Range

39.2 38-40

39.2 38-40

38.5 38-39.5

39.0 38-39

38 . 8 37-40

38.7 37-39.5

39.3 38-40

38.8 37-40

lThe offic ial American Dairy Science Association scorecard was used, with the highest score a numerical value of 40.

2presterilized glass bottles, filled simultaneously with the cartons.

3The number of samples receiving a score of 32 (unacceptable).

24

Table 5

Flavor evaluations l of milk stored ~n ros~n paperboard - foil lined cartons

Weeks at

0

I

2

3

4

6

8

9

Rosin Foil Cartons

x Range

38.3 35-40

38.6 36-40

38.7 36-40

38.7 36.5-39

38.7 35-40

37.2 34.5-39

38.2 36.5-40

37.2 32--39.5(2)3

Contro1 2

x Range

37.2 32-400 )

36.2 33-38

37.5 36-38

37.4 34-39

38.2 37-39

38.0 35-39

37.4 36-39

37.8 36-40

Pasteurized Milk (Not Stored)

x Range

39.2 38-40

39.2 38-40

38.5 38-39.5

39.0 38-39

38.8 37-40

38.7 37-39.5

39.3 38-40

38.8 37-40

IThe official American Dairy Science Association scorecard was used, with the highest score a numerical value of 40.

2presterilized glass bottles, filled simultaneously with the cartons.

3The number of saU'_~les receiving a score of 32 (unacceptable).

25

Table 6

Flavor evaluations l of milk stored in . ..

cyanaslze-Julce paperboard cartons

Weeks CJ Cartons Contro1 2 Pasteurized Milk at (Not Stored)

200 C X Range X Range X Range

0 38.0 35-39.5 39.3 38-40 38.6 37-40

1 38.3 36-40 38 . 6 37-40 38.8 37-40

3 37.2 33-40 37.4 36-39 38.8 37-40

4 36.8 32-40(1)3 36.5 36-38 37.9 37-38.5

5 37.8 35.5-39 36.0 32-40( 1) 3 37.8 35-39

7 36.6 32-39( 1) 3 37.3 35-39 38.3 38-39

8 37.1 34-39 37.4 36-39 38.2 37-39

9 36.8 32-40( 1) 3 36.0 35-39 38.6 37-39.5

lThe official American Dairy Science Association scorecord was used, with the highest score a numerical value of 40.

2presterilized glass bottles, filled simultaneously with the cartons.

3The number of samples receiving a score of 32 (unacceptable).

26

Table 7

Flavor evaluations of milk stored ~n . . . paperboard - foi I-lined cartons cyan~ze-Ju~ce

Weeks CJ Foi I Cartons Control 2 Pasteurized Milk at (Not Stored)

20 0 C X Range X Range X Range

0 38.2 35-40 39.3 38-40 38.6 37-40

1 38.1 32-30(1) 3 38.6 37-40 38.8 37-40

3 37.5 33-40 37.4 36-39 38.8 37-40

4 36.4 30-40 36.5 36-38 37.9 37-38.5

5 37.5 36-40 36.0 32-40(1)3 37.8 35-39

7 37.4 37-39 37.3 35-39 38.3 38-39

8 37.5 34-39 37.4 36-39 38.2 37-39

9 36.7 34-40 36.0 35-39 38.6 37-39.5

lThe official American Dairy Science Association scorecard was used, with the highest score a numerical value of 40.

2presterilized glass bottles, filled simultaneously with the cartons.

3The number of samples receiving a score of 32 (unacceptable).

DASI sterilized milk received the highest score during a taste test at the 1976 Dairy Marketing Forum sponsored by the USDA Cooperative Extension Service and the University of Illinois at Urbana-Champaign. The taste test re~ults are shown in Table 8.

In his letter dated April, 1976, Professor James W. Gruebele wrote:

"I want to express my appreciation to you and your organization for displaying the sterilized milk product at the 1976 Dairy Marketing Forum. The taste test results at the Forum certainly point out that your organization has an excellent product. Not only did it rate higher than any other product samples this year, but it also received the highest acceptance score that we have had for any product in the last several years. The acceptance score we used in the taste test ranged from I-dislike to 9-like very well.

27

Your product's acceptance score was 7.06 . In 1972, 2 percent milk received the (previous) highest acceptance score of 6.6. Homogenized milk received a score of 6.1 that year. One cannot always meaningfully compare acceptance scores in different years because there are some changes in forum participants from year to year. But it is obvious that your firm should be proud of an acceptance score of 7.06."

In a seminar on UHT processing held at the University of Minnesota in July, 1977, DASI 2 percent UHT milk was compared with regularly pasteurized 2 percent milk and conventionally-sterilized 2 percent UHT milk. Again, the DASI product received the highest mean rating based on the 9-point Hedonic scale with 6.6. The pasteurized product received a mean score of 6.2, and the other UHT milk received a mean score of 5.6.

Sample Product

Sterile Whole (DASI)

Homogenized Whole

Imitation Lowfat

Table 8

Dairy Marketing Forum--Taste Test Results

Percent Identifying Product as: Sterile Whole Homogenized Imitation

Average Score (DASI) Whole Lowfat

7.06 26.8 62.0 11. 2

6.18 54.9 28.2 16.9

4.54 19.7 9.9 70.4

Summary and Recommendations

This research demonstrated that milk sterilized as a free falling film in a saturated steam environment produced a product which consumers would find comparable to existing pasteurized milk. It was further determined that substantial energy and nonenergy savings would result from the introduction of this product. Details can be found in the original reports Harris ~ ~., Volume I, II and III.

Table 9 summarizes the annual energy savings associated with replacing conventional pasteurized milk with sterilized milk in the current industry. Since it is recognized that it takes time for an industry to adopt any innovation, the study team projected a rate of adoption which seemed reasonable based on past experience with the American dairy industry. This rate of adoption is illustrated in Figure 5 and is predicated on the assumption that a successful demonstration project would initiate adoption as early as 1983.

Table 10 summarizes the annual and total energy savings that might be anticipated by the year 2000. Although an immediate conversion of the entire industry to sterilized milk would require additional capital of $858 million, it is estimated that the conversion implied by Figure 5 would require less capital

28

Table 9

SAM PROJECT ESTIMATES - ANNUAL ENERGY SAVINGS

Pessimistic Most Likely Optimistic Sector Estimates Estimates Estimates

(trillion Btu) (trillion Btu) (trillion Btu)

Processing Plant -2.9 0.0 0

Transportation Trucks 2.8 6.0 12 N Retail \.D

Storage/Display 19.0 24.0 29

Transportation Consumer 8.0 24.0 46

Home Storage 0.0 1.2 14

Institutions - .7 2.0 4

Returns & Spoilage .8 10.7 22

TOTAL 27.0 67.9 127

80 I

Total Fluid Milk Market I

(/) 60 "0 I ~ SA M Production c :::1 0 ~ - 40 0

w (/) 0 c::

0 .--iii 20

DL. ~~ __ L-~-L~~L-L-~-L-i~L-~~-L~~~ __ ~~ 1983 85 87 89 91 93 95 99 2000 97 Year

Figure 5: Projected Market Penetration of SAM

than maintaining current practice because of the reduction In investment in refrigerated storage and distribution systems.

The present values of the projected savings, In 1978 dollars are:

Year

1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

Capital savings Energy savings Nonenergy savings Manufacturing cost

Total

Billions of Dollars

Table 10

.702 1. 731 4.660 - .138 6.955

Estimates of total market for fluid milk, projected SAM production levels and resulting energy savings, 1983-2000

Total Market Size Fluid Milkl

(millions of pounds)

59804 60390 60976 61561 62146 62730 63295 63839 64363 64865 65345 65802 66236 66654 67047 67416 67759 68078

(2)

SAM Milk Production l Energy Savings 2

(millions of pounds) (trillions of Btu)

2990 3.6 6643 8.1

14024 17 .0 23393 28.4 33559 40.7 44538 54.0 51902 63.0 55540 67.4 57927 70.3 58378 70.8 58810 71.3 59222 71.8 59612 72.3 59989 72.8 60342 73.2 60674 73 .6 60983 74.0 61270 74.3

TOTAL 1006.5 3

lDerivation of these estimates IS outlined in Harris, ~~., Volume III.

2Pounds of SAM production from column (2) multiplied by 1213 to convert to BTU.

3Total energy savings (1006.5 x 1012 Btu) is approximately equivalent to 185 million barrels of oil.

31

In physical terms, industry conversion would save 1,006 trillion BTU (185 million barrels of oil) by the year 2000.

Figure 6 shows the cumulative present value of energy savings, nonenergy savings and increased manufacturing costs which might reasonably be anticipated.

With the substantial savings that will result from the introduction of sterilized milk, it is the judgement of the study team that it is only a matter of time before economic incentives become great enough that the industry will act of its own volition. However, it may take many years before industry acts on its own. As Figure 7 shows, a delay of even 10 years because of the lack of a successful demonstration would result in a severe reduction in the present value of the savings streams.

The following factors are of primary importance 1n terms of successfully introducing sterilized milk for the American public:

Economic Considerations

Dairy and allied industries, as well as the public, are likely to accept SAM only after it has proved itself as an economical product. Towards this end, the following economic considerations must be taken into account:

•

•

•

Dairy farmers and cooperatives must have assurance that SAM is classified as Class I milk. Since dairy farmers can benefit from the introduction of SAM, they could have a substantial impact on its introduction and acceptance.

SAM could accelerate the existing trend to larger, centralized dairy plants. Large and efficient plants with wide distributing areas would most likely support SAM while smaller, local dairies may have to specialize in particular products or markets.

Introduction of SAM will require substantial capital investment. Processors must consider the cost of new equipment which includes the sterilizer, equipment modifications to maintain sterility, and equipment replacements that cannot be modified. For example, Slnce existing packaging equipment is not adaptable to modification for ensuring sterilization, replacement of conventional packaging equipment will be a major cost. Dairy Plants with relatively new equipment will have greater replacment problems than those with older equipment which is fully or nearly depreciated. There may be some offsetting savings of operating costs resulting from reduced refrigerated transportation and storage.

• Labor requirements may decline because of shifts in skills, increased efficiency in new handling systems, and less frequent deliveries as milk is warehoused and handled like other less perishable food products.

32

4800~

4200

3600

3000

2400 UJ

1800 L ... co 0 c 1200 -0 UJ 600 c w 0 w

- 0 :! 1983

-40

-80

-120

-160

/

85 87 89 91 93

Non-Energy Saving

Energy Saving

95 97 99 2000

Manufacturing Cost (Note Scale Change)

Figure 6: Cumulative SAM Estimates for the Most Likely Case

Year

w .j::-.

80

L __ --------------~T~~~a~I~F~IU~id~M~il~k~M~a=r~ke~t~-----------------­

t/) 60 -g Sam Production ( ( ( ( ( ( \ \ \ \ \ \ \ \ \ \

5 With Demonstration a. (5 40 t/)

c: o

iii 20

1983 85 87 89 91 Year

93 95 97 99 2000

Figure 7: Acceleration of adoption of SAM due to Phase II Demonstration

Regulations

• While the price of sterilized milk to the consumer should eventually be lower than pasteurized milk, at its introduction, prices may be higher. This is because of initial investment costs and having to produce both refrigerated and unrefrigerated milk for a period of time. Small price differentials do not seem to have a significant impact in certain European countries.

• Some costs will be incurred in informing the public of SAM and generating confidence in its safety, flavor, and economy.

• The longer shelf life of sterilized milk is not expected to result in substantial increases in inventories at the processing plant or the retail store. Evidence from the soft drink industry indicates that the increased shelf life is utilized primarily for in-home storage by the consumer.

The United States dairy industry, in contrast to other agricultural industries, was for many years subjected to a complicated set of nonuniform federal, state and local government regulations. Local health regulations, for example, were once a major obstacle to the movement of milk. By the 1940's, a large variety of city health regulations were more restrictive than state or federal regulations. While the complex, rigorous system minimized the dangers of milk-borne disease, it also had an unintentioned economic impact on the development of the dairy industry. The local health regulations provided market protection and were responsible for increasing production, processing, and distribution costs. The protected markets caused both higher profits than would normally have occurred as well as production and distribution inefficiencies that resulted from the inability of firms to optimize plant size and operating capacity. Competitive behavior of milk trade organizations was influenced and innovative progress hindered.

Court decisions, however, have invalidated local provisions not directly related to public health. The local health regulations have been largely replaced by state and federal codes, reducing the use of sanitary regulations as a barrier to producers entering the market. The methods for regulating fluid milk prices, as well as for protecting the public from contaminated milk, consist of federal and state milk marketing orders, local sanitary regulations, federal health codes and state regulations controlling trade practices, resale prices, and minimum prices received by producers.

Federal and state marketing orders regulate prices of nearly all Grade A milk used in packaging fluid milk products. Uniform prices are ensured for all processors and all farmers in a marketing order area. Federal orders, promulgated by the USDA, and numbering 47 in all, directly affect 78 percent of all milk. The adoption of the United States Public Health Service milk ordinance and codes with participation in the Interstate Milk Shippers Certification Program have combined to ease unification of sanitary milk standards.

35

:y

Legal Considerations

In approving a nonrefrigerated sterile milk, federal and state regulatory agencies will be making decisions that require an alteration of "'safe" regulations; for example, refrigeration storage requirements and "sell-by date" requirements must be modified. Furthermore, there may be legal implications for movement restrictions of milk between market order areas; the exclusive system franchise requirements could be a legal adoption barrier.

There is no more viable alternative for eliminating regulatory barriers than providing research data to the appropriate federal agencies in which fail-safe operation criteria and product safety expectations of the system are demonstrated. No state agency will approve the system without federal approval. All regulatory agencies must be kept fully informed of the system and all recommendations submitted by them must be thoroughly investigated.

36

References

Babb, E.M. and W.T. Butz, "Improving Fluid Milk Distribution Practices Through Economic - Engineering Techniques", Bulletin 62, Pennsylvania State University, June, 1957.

Baker, C.B., et al, "Programmed Production Responses on Dairy Farms in Northeastern Illinois", Bulletin 708, University of Illinois Agricultural Experiment Station, March, 1965.

Batty, J. Clair, Energy Perspectives for the Dairy Industry, Utah State University, September 1977.

Bell, J.A., M.D. Beck, and R.J. Heubner, "Epidemiological Studies of Q Fever 10

Southern California", Journal of the American Medical Association, 142, 868-872, 1950.

Bureau of the Census, 1972 Census of Manufactures--Fuels and Electric Energy Consumed, July 1973.

Bureau of the Census, 1972 Census of Manufactures--Industry Series: Dairy Products, March 1975.

Bureau of the Census, Annual Survey of Manufactures 1974--Fuels and Electric Energy Consumed.

Bureau of the Census, Annual Survey of Manufactures 1975--Fuels and Electric Energy Consumed, September 1977.

Bureau of the Census, Annual Survey of Manufactures 1976--Fuels and Electric Energy Consumed, March 1978.

Burton, H., J.G. Franklin, D.J. Williams, H.R. Chapman, A.J.W. Harrison, L.F.L. Clegg, "An analysis of the performance of an ultra-high temperature milk sterilizing plant. III. Comparison of experimental and calculated sporicidal effects for a strain of Bacillus subtilis", Journal of Dairy Research, 25, 338, 1958.

Burton, H., "Some Observations on the Performance of Ultra-high Temperature Milk-sterilizing Plants", 15th International Dairy Congress, London, 4, 2045, 1959.

Dansbury, Kenneth P., A Case Study Analysis of Energy Utilization and Conservation Potential in the MSU Dairy Plant, MSc. Thesis, Michigan State University, 1978.

DASI Industries, Inc., "Evaluat ion of Free Falling Film Ultra-High Temperature Processed Milk", First Interim Report for the Period ending August 31, 1978, prepared for NSF Grant No. AER77-04l62, DASI Industries, Inc. 5454 Wisconsin Avenue, Chevy Chase, MD . 20015, 1978.

Development Planning and Research Associates, Inc., Industrial Energy Study of Selected Food Industries, July 1974.

37

Development Planning and Research Associates, Inc., Energy Effic iency Improvement Targets-Food and Kindred Products Industry--SIC 20, Volume 2, Appendix Report, Part I, June 1976.

Ennis, D., "General plot program for the offline digital plotter", University of Maryland Computer Program Library, 1975.

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