Milk to Market: Low-cost methods to pasteurize milk in ...Milk to Market: Low-cost methods to...

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Milk to Market: Low-cost methods to pasteurize milk in East Africa Report Information Purpose: To support a study of low-‐cost milk sterilization Report Date: March 11, 2010 Organization Name: Social Profit Network with D-‐Rev: Design Revolution Report Prepared by: Krista Donaldson, Heather A. Hoell Report Edited (2011): Jacqueline del Castillo, Sara Tollefson, Hannah Lou Primary Contact Name: Krista Donaldson Title: CEO, D-‐Rev: Design Revolution Telephone: (650) 485-‐2090 Address: 631 Emerson Street, Palo Alto, CA 94301 E-‐mail: kdonaldson@d-‐rev.org Web site: www.d-‐rev.org Report Disclaimer D-‐Rev provides information about its projects to build a community of innovators and entrepreneurs that address societies' most pressing problems. Please reference this report as follows: D-‐Rev "A study of low-‐cost milk sterilization in East Africa," 10 January 2010, D-‐Rev Report #MTM01, URL: www.d-‐rev.org/reports/11-‐10-‐05-‐d-‐rev-‐milk-‐to-‐market-‐report.pdf

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I. Background & Rationale The Problem Remote rural farmers with dairy livestock have an acute problem getting their milk to market, since unpasteurized milk spoils in as short as four hours in 30º C temperatures1. This is especially true for dairy farmers in Sub-‐Saharan Africa where population dispersal and poorly maintained infrastructure, particularly roads, make milk collection and distribution to the market difficult. Standard methods used in industrialized and urban areas for sterilizing and preserving milk (e.g. refrigeration) are too costly for smallholder dairy farmers living in remote regions, limiting their ability to sell milk for cash income. They are confined to selling their milk to nearby informal traders at below-‐market prices or trading it with neighbors. The UN’s Food and Agriculture Organization (FAO 2004) estimates that over 80% of milk produced in East Africa is traded in the informal market, noting that “small-‐holder farmers and traders are the backbone of this essential supply chain, which provides much needed milk and dairy products to growing regional towns and capital cities.” The challenge of transporting the milk from the farm to the chilling plant or market remains the main gating issue. To limit spoiling, farmers must bring their fresh milk to the plant immediately after milking, which typically occurs twice a day (morning and evening). For many farmers, this is simply not possible – they live too far away. Instead farmers sell their milk to milk collectors who come by bicycle to their farms, typically in the morning (See Appendix F). The long distances and the hot climate mean that the

collector’s milk is also at risk of spoilage and contamination as he goes on his collection rounds. It is possible that some or all of his milk could be rejected at the plant. In industrialized economies, food is commonly sterilized by either irradiation or, in the case of liquids like milk, ultra-‐high temperature (UHT) pasteurization (e.g. “milk in a box” such as Parmalat; See Figure 1). UHT pasteurization, however, is costly because it requires high energy and water inputs to rapidly heat the milk to 110º C for 2 seconds and then flash cool it back to room temperature. The start-‐up costs for UHT pasteurization are

not insignificant: a medium-‐sized UHT facility is approximately $1M US. UHT is simply not economically or technologically feasible for bottom of the pyramid (BOP) small-‐scale dairy farmers.

1 Average monthly temperatures in East Africa range from 21-36ºC depending on elevation and location (MSN UK 2010).

Figure 1. Parmalat UHT milk

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If farmers had access to a low-‐cost on-‐farm method for extending their milk’s time until spoilage (shelf-‐life), their market opportunities, thus incomes, would increase, as would the overall quality of the milk supply. History of the Problem Scientifically, milk spoils because bacteria grow in it. Once a high level of bacteria exists, it spoils. In the United States, industry standards put spoiling at 100,000 colony forming units per milliliter (CFU/mL), but humans do not detect spoilage until they can taste sourness at approximately 10M CFU/mL. Figure 2 depicts the exponential growth of bacteria at 26ºC (79ºF) with time counting down from 24 hours. The model illustrates environmental staphs, streps, and coliforms typically found in milk. During the first 16 hours, if the initial bacterial count is low,

there is no detectable change in taste or spoilage of the milk. Commonly applied ethanol tests and the free oxygen dye tests, such as the Resazurin 10 minute-‐test, cannot detect bacterial contamination below 20M CFU/mL. Milk spoilage occurs in the last 2-‐3 hours when the bacteria populations exponentially “explode”. As a general rule of thumb: every 10x reduction in bacterial inoculation translates to just over three doubling cycles at 28ºC or an additional 2 hours until spoilage. There are few methods viewed by the development community as economically and technologically

feasible for extending the shelf-‐life of milk produced by small-‐holder farmers: boiling to sterilize the milk, and chilling to preserve it. Boiling milk is widely practiced in rural East Africa. The capital costs for a small cook stove are low (<$5 USD) or negligible since most families already have one. The cost of fuel, however, can be high depending on scarcity: as much as 10% of the value of the milk or about $0.03 per liter. Furthermore, boiling milk negatively impacts the taste and nutritional content of the milk. Chilling with refrigeration systems has high upfront capital and operating costs for power2. Furthermore, refrigeration systems do not scale down well below 500L making them

2 In East Africa, electricity from diesel generators is five times more costly than solar panels for basic refrigeration units.

Figure 2. Milk spoilage rate at 26ºC

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unaffordable to most farmers, although they may be economically feasible at collection points with a reliable power source that provides 30 kilowatt-‐hours (kW-‐h) for less than $8 per day. Since most farmers cannot afford refrigeration (and the associated energy costs), a farmer must start with a low initial bacterial level if he/she wants to extend his/her milk’s shelf-‐life. There are two complimentary ways to do this: (1) protect the milk from bacteria inoculation (disinfection) and (2) kill the bacteria off before spoilage can occur (pasteurization). Currently, off-‐grid widely-‐distributed small-‐holder farmers do not have viable sterilization or preservation options that allow them to bring their milk to market. Magnitude of the Problem According to the UN Food and Agriculture Organization (Lore 2004), economic losses due to spoilage and waste in the dairy sectors of East Africa and the Middle East are as high as $90M per year. These “losses” are attributed to “a combination of poor production and handling and a lack of technical knowledge related to possible sterilization options.” Table 1 shows that the total of estimated economic losses in Kenya, Tanzania and Uganda due to milk failing to reach market is $56.4M USD (FAO 2004).

Table 1. Estimates of economic loss due to milk failing to reach market in East Africa (FAO 2004)

Country Milk Produced (L) Milk Marketed (L) Milk Loss Amount (L) Economic value (USD)

Kenya 2550M 585M 95M $22.4M Tanzania 1000M 271M 60M $11M Uganda 900M 585M 123M $23M Total 4450M 1441M 278M $56.4M We learned from fieldwork, however, that farm-‐level milk was not so much “lost” to spoilage as it was never making it to market. We found that if milk could be preserved for 8-‐12 hours more, then it could actually reach market. Milk that could not go to market was usually sold informally at below-‐market prices, traded with neighbors and/or given to family members and livestock.

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II. Goals, Objectives, and Activities Our initial objectives as stated in our proposal changed as we learned more about the problem and the limitations of UV-‐C technology for sterilizing fresh milk (see Table 2 and VI Challenges for more information).

Table 2. Original and updated objectives Original objectives (December 2008)

1. Build and test basic 100-‐200 liter UV-‐C portable milk sterilizer. 2. Build and test large-‐scale 1000-‐5000 liter UV-‐C system.

Updated objectives (May 2009)

1. Create a portable, low-‐powered system for <$100 that adds 3-‐8 hours over the existing time to spoilage. 2. Create a scaled-‐up version of our first system for <$400 to fill 50-‐liter milk drums with sterilized milk in lieu of chilling at local collection points.

See Appendix A for the visions of success, activities, outputs and outcomes associated with the updated objectives. Activities carried out to meet objectives To meet Objective #1 (see Figures 3a-‐c), we:

• designed, prototyped and tested a UV-‐C sterilization system for farms • designed, prototyped and tested using an electro-‐chlorinator to provide low-‐

cost bleach for sterilizing milking, storage and transport containers • prototyped, using a simple off-‐the-‐shelf kitchen thermometer, a low-‐cost

system to pasteurize milk at low temperature To meet Objective #2: we:

• rapidly prototyped and laboratory tested a larger-‐scaled UV-‐C sterilization system for aggregation points

Figures 3a-c. Three D-Rev technologies field-tested in Uganda to improve milk shelf-life (from left to right): (a) the electro-chlorinator to produce low-cost bleach, (b) low temperature pasteurization using a simple kitchen thermometer, and (c) UV-C pasteurization.

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UV-‐C sterilization system for farms Working with Niparajá, students and researchers at the University of Arizona, D-‐Rev developed an austere version of cold pasteurization of milk using UV-‐C ionizing radiation, which is inexpensive to generate and uses little electricity (see Figure 3(c) and Appendix D for design requirements, product figures and drawings). Tests run at the University of Arizona provided a positive proof-‐of-‐concept with over 94% reduction in countable bacteria when treating 1 liter per minute of milk. This prototype used dual UV-‐C lamps. In the course of our product development process, we ran into two challenges in the laboratory: it was difficult to create a consistent thinly-‐flowing curtain of milk under the UV-‐C lamps, and the energy demands for treatment were higher than expected. Our team did additional form factor iterations to achieve the appropriate flow of milk to maximize treatment. The energy demands, however, were problematic because a single 20W bulb was not sufficient to produce the 99.9% reduction in bacterial loads. Instead four bulbs with a lower flow rate were required (resulting in a treatment time of 2 hours!), or alternatively, additional lamps were required to increase the speed of the treatment. We determined that a four-‐bulb system capable of processing 100 liters per day required a power input equivalent to a $60 car battery and 160 W-‐h of daily available power. A 50 W solar panel capable of providing this input increased the cost by $200, resulting in a significant increase in estimate cost relative to initial estimates – affordable only perhaps to the aggregation points where collectors bring their milk to be aggregated and taken to a chilling plant. Despite the technical and cost challenges, we tested the UV-‐C sterilization system in the field and confirmed that it would be most appropriately placed at an aggregation point. Unfortunately the UV-‐C system did not, however, perform well in testing: it was overly sensitive to operating conditions (specifically, tilt), and was unable to treat fresh milk because the UV-‐C rays did not easily penetrate the cream layer. Electro-‐chlorinator for sterilizing storage containers Cleaning and sterilizing everything in the milk-‐handling and storage chain is crucial to extending milk shelf-‐life (see Appendix F). Even a small amount of residual contamination in a jerrycan effectively inoculates the milk with bacteria and can rapidly accelerate spoilage. D-‐Rev felt it was necessary to complement the UV-‐C pasteurization with a low-‐cost bleach to sterilize the storage vessels (see Figure 3a). Chlorine bleach is affordably produced using an electro-‐chlorinator which converts a small amount of salt water to bleach. D-‐Rev’s design of the electro-‐chlorinator for use on rural East African farms is based on technology already developed in partnership with Cascade Designs and MIOX Corporation. The electro-‐chlorinator performed very well in field testing and was popular with farmers, particularly women farmers, excited not only about its potential for cleaning storage containers, but to sanitize and clean other household items as well.

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Low temperature pasteurization using a simple kitchen thermometer Once determining that the UV-‐C technology would be too expensive for on-‐the farm pasteurization, our team undertook research to find an economically and technologically feasible means for farmers to sterilize their fresh milk. Pasteurization at a lower temperature does not degrade the milk or noticeably change its taste. Thermal pasteurization is also easy to teach since it is simply heating the milk to a precise temperature for a specified period of time. To do this, farmers simply use a thermometer and controllable heat source. For example, during field testing, we showed farmers how to pasteurize by heating the milk to 69º C for 15 seconds using a gasifier stove (see Figure 3b). This type of pasteurization has a low upfront cost for rural farmers, particularly compared to UV-‐C pasteurization technology. A drawback of thermal pasteurization relative to the UV-‐C treatment, however, is the cost of fuel to heat the milk. The fuel cost for low temperature pasteurization, however, is approximately half the fuel cost for boiling. UV-‐C sterilization system for aggregation points Working with students and researchers at the University of Arizona, D-‐Rev designed and rapidly prototyped a larger UV-‐C system for sterilizing milk. Because of performance challenges encountered in the field with the smaller unit, much of the technical product design was focused on mixing the fresh milk for UV-‐C penetration (see Figure 4). Activities not completed

We did not carry the larger-‐scale system into beta design for field-‐testing for two reasons. First, the estimated costs of the smaller and larger units, once factoring the increased power requirements, moved well beyond target price points. Second, the smaller unit performed poorly in the field and we felt more research and redesign was required for UV-‐C technology before moving ahead with the larger system (see VI Challenges for more information). Before continuing with Objective #2 and developing units for field testing, further testing and redesign are required to (1) ruggedize the product so it is not overly sensitive to usage conditions and (2) explore viable low-‐cost options for mixing (homogenizing) the milk to eliminate the cream barrier.

Figure 4. Rapid prototype for mixing fresh milk for effective UV-C sterilization.

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Activities completed in addition to original proposal Our original proposal focused principally on UV-‐C technology to sterilize fresh milk with complementary sterilizing of containers using low-‐cost chlorine bleach produced with an electro-‐chlorinator. In the course of our technology development process and laboratory and field testing, we found that UV-‐C technology has serious limitations that strongly suggested that it was not a viable solution for smallholder dairy farmers and their informal networks of milk buyers and sellers. To better understand and address the problem, we collected data on contamination in the stakeholder chain (see Appendix F) and refocused efforts on finding an affordable means to pasteurize milk on the farm. This research led us to pursue low temperature pasteurization, which was in addition to the original proposal. Additional accomplishments Upon recognizing that UV-‐C would not be a viable market-‐driven option for farms, D-‐Rev stepped back to consider the goal of the project, which we understood was to extend the shelf-‐life of milk so that farmers could bring more of their milk to market, thus increasing their incomes. D-‐Rev’s team then undertook a review of existing milk sterilization, storage and transportation research and development with the East African requirements and conditions in mind. Based on our testing of storage containers, knowledge of conditions in East Africa and a survey of methods, we refocused our efforts on disinfection (keeping bacteria out of the milk) and pasteurization (limiting bacteria in the milk). Our additional accomplishments:

1. Rigorous bacterial testing throughout milk chain and identification of jerrycans as main contamination points. Our aim in measuring bacterial load in milk was to determine where the milk was being inoculated so as to best target our interventions. While anecdotal data existed generalizing where contamination points were, there was no literature or verifiable data that provided the necessary insight.

We used standard plate counts (SPCs) to find bacterial contamination (see Appendix E). SPCs, one of the most rigorous quantitative tests, involve sampling milk with 3M® petrifilm and then incubating it at 37ºC in a small egg incubator. We identified the main bacterial inoculation points in the dairy chain to be when the milk was transferred into contaminated storage vessels; typically, these were the ubiquitous plastic jerrycans. We then targeted our interventions, either preventing contamination with chlorine bleach or pasteurizing after the

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contamination to eliminate the bacteria. As seen in Appendix E, we incubated several hundred plates based on the data we collected with the Ugandan farmers.

There are many opportunities for milk to become contaminated on the farm and along the collection routes (see Figures 5 and Appendix F). The first contamination point is milking (Figure 5a). The open, generally unsanitary conditions under which cows are milked permits bacterial inoculation from a number of sources, such as dirt, flies, fecal residue, etc. (see Figure 5b). As part of the East African Dairy Development (EADD) project, local staff have been working successfully with farmers to improve hygiene including the washing of hands, the cow’s teats and milk collection buckets. Using the bleach produced by the electro-‐chlorinator to clean hands, teats and the bucket reduced the initial bacterial load by 1.5 orders of magnitude. We found, however, that the initial bacterial load was remarkably low (in the hundreds or few thousands) at these sampling points. We had one case where the bacterial count jumped significantly despite the added bleach washing; in this case, the milk had been contaminated by another (unwashed) milking bucket. Even with low levels of contamination, a single drop of contaminated water or particle of dirt can cause a drastic percentage increase in bacterial counts (see Appendix E). We concluded based on our data collection that the milking process is not a major source of contamination. Despite this finding, fresh milk was observed to spoil in less than 12 hours during storage and transport to market. For milk to spoil in this timeframe, the initial bacterial load would be approximately 50,000 CFU/mL.

Figures 5a-c. Milk sampling points (from left): freshly expressed milk, transfer from milking cup to farmer’s storage and bike trader/collector’s jerrycans.

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We determined from our field data collection that the main contamination point is the jerrycans used for storing and transporting the milk once it leaves the farm. These plastic jerrycans, as seen in Figures 5c and 6, cost $1.80 -‐ $2.00 and are used both on the farm and by milk collectors. We found that the jerrycans inoculated the milk up to 200,000 CFU/mL (see Appendix E). The standard jerrycans in use in East Africa (see Figures 6) have small mouths and it is impossible to fit one’s hand inside to clean thoroughly. The inside of the jerrycans have a rough interior with flash and seams from manufacturing. The flash, seams and handle areas are ideal geometries for protected bacteria breeding since the milk residue is difficult to clean out. Furthermore, many of the jerrycans used for transporting milk are not made of food-‐grade plastics (see Figure 6b).

2. Research and testing of milk flow paths and geometries to determine optimal mixing for maximum UV-‐C penetration. Once understanding the limitations of the UV-‐C technology, we tested four geometric configurations with two different types of inoculated sample milk. (See Appendix G for results from our work).

3. Determination of low temperature pasteurization best suited to on-‐the-‐farm

pasteurization. Based on economic analysis, field work and user input, we determined that low temperature pasteurization where the farmer heats her milk to 69º C for 15 seconds to be the most viable means to extend the shelf-‐life of fresh milk on the farm. The payback period for low temperature pasteurization was also estimated to be less than two weeks (see Appendix H).

Figures 6a, b. Jerrycans used for milk storage and transportation in Kamira (left) and near Luwero, Uganda (right). Note the oil container being used for milk storage (right).

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III. Accomplishments Our top five accomplishments were:

1. Better comprehension of the problems facing farmers and stakeholders in the East African smallholder dairy chain. As mentioned earlier, there was a good deal of anecdotal evidence and data suggesting the challenges of bringing small-‐holders’ milk to market. We were able to establish through rigorous data collection, analysis and need-‐finding that jerrycans were the main source of contamination as milk is moved through storage vessels from the cow to distribution centers (see Appendices E and F). We also documented other sources of contamination related to user activities that had not been previously reported (see V Lessons Learned).

Table 3. Overview of Approaches Tested by D-‐Rev to Extend Milk Shelf-‐life in East Africa

UV-‐C sterilizer system Electro-‐chlorinator

Low thermal pasteurization

How does it work?

It kills pathogens in milk by radiating a moving thin

film of milk

It sterilizes the inside of storage vessels and other surfaces the milk contacts,

preventing bacterial inoculation

It kills pathogens in milk by heating the volume evenly to

160ºF for 30 seconds

Required consumables electricity: 1 W-‐h/L

table salt and filtered water (1oz of salt per gallon of

bleach)

Bio-‐fuel for stove (charcoal, wood)

Recurrent cost per L $0 $0.001 $0.02 ($0.007 with a gasifier

stove) Initial cost $380 with 80W solar panel $35 with 4W solar panel $4 (accurate thermometer)

Time to treat 0.5 L/minute 5 minutes per cow to wash all vessels, hands, teats, etc 0.5 L/min for 8 L batches

Total cost for 1st year (100

L/day) $350 $71 $735x$250 with improved

stoves

2. Completed preliminary design, testing and analysis of UV-‐C technology for milk

sterilization in East Africa.

Although laboratory tests had initially suggested that UV-‐C technology was promising as a low-‐cost method for sterilizing milk on farms, we found that in field tests that fresh milk was not easily treated by UV-‐C. For the system to be affordable, we believe UV-‐C systems need further exploration and research and should be aimed at “aggregation points” in the customer chain (see Appendix F).

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3. Analysis of viable market price points.

D-‐Rev believes that for products, whether physical artifacts or services, to increase income generation among BOP populations, they must be market-‐driven. We undertook price point and payback period calculations throughout our design process to ensure that introduced technologies would have the anticipated positive impacts. (See Appendix H).

4. Developed and field tested an electro-‐chlorinator for making low-‐cost bleach;

determined that it had market potential among East African farmers. During field testing, we talked to farmers about our findings on contamination points in the dairy chain and solicited their feedback. Two major themes emerged; both of which also came up during our preliminary need assessment field work in August 2008: (1) farmers want to sell their evening milk, and (2) they were extremely concerned with the prospect of rejected milk as that represented lost income. We learned that in Kamira, for example, that on average one farmer’s milk was rejected per week. When this happens, the trader returns the spoiled milk, now semi-‐rancid, at the end of the day and tenders no payment to the farmer.

5. Prototyped and field tested low temperature pasteurization; determined it had

market potential for on-‐farm pasteurization. After trying out the UV-‐C and the low temperature pasteurization, farmers greatly preferred the thermal pasteurization. By the end of our user feedback gathering, there was significant demand among the farmers for the $4 off-‐the-‐shelf kitchen thermometers for the low temperature pasteurization. The UV-‐C systems elicited curiosity from farmers but the estimated retail price of $200-‐$380 was too high.

From our team’s perspective, we observed two further advantages of the thermal pasteurization over the UV-‐C system. First, heating, stirring and using a thermometer is an easy and straight-‐forward protocol for farmers. Second, thermal pasteurization of this type is similar to what other small-‐scale dairy farmers use all over the world. We presented it to farmers as a farm-‐scale version of what the larger sophisticated East African dairies do. The farmers responded favorably, telling us that they aspired to modernize sanitary dairy practices.

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IV. Impact Because this project was a technology development project, we do not have reportable impact to users other than feedback from farmers, milk collectors and milk distribution center workers on prototypes. The farmers (and EADD staff) were most impressed when we were able to demonstrate that with chlorine bleach to clean jerrycans and low temperature pasteurization of fresh milk, it was possible to preserve milk for over 21 hours without impacting the milk’s taste. From a farmer’s perspective, this represents a new income source – he or she can store evening milk overnight (~12 hours, well below any detectable level of deterioration) and add it to the morning milk for sale to collectors. We estimate that a farmer with a moderate to high producing cow would earn an extra $3.15 per day (see Appendix H). To bring these farm-‐based interventions to impact, the next step would be to develop distribution and commercialization plans for the electro-‐chlorinator and kitchen thermometer, test market them and launch the product to East African markets. For larger systems, such as the 1000-‐5000 liter UV-‐C sterilization system, additional research needs to be done around aggregation points and on the UV-‐C technology to make it affordable and field-‐ready. V. Lessons Learned What worked well and what did not? As detailed in IV Impact, the farmers greatly preferred the thermal pasteurization to UV-‐C pasteurization, and there was significant demand among farmers for the $4 off-‐the-‐shelf kitchen thermometers. Farmers also told us they would use the electro-‐chlorinator to make bleach for other purposes. At $0.75 for a 150 mL bottle, the local bleach Jik is too costly to be afforded by most farmers. Using local inputs (salt at $0.50/kg and available water) 150 mL of the chlorine bleach costs less than 1¢. What recommendations do we have for other organizations attempting similar efforts? First, we recommend that they partner with ILRI and other knowledgeable organizations located in East Africa to best have access to and understand user needs. Second, we were unable to find reliable data (scientifically sound) that provided the necessary insights for product development. If we were to plan this project again, we would spend more time upfront doing user research, as well as a rigorous study of the

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local economies, current methods in use and user habits. This early stage work would have better informed our product development process, particularly in designing for scale. Finally, based on the farmers’ positive and enthusiastic responses to the electro-‐chlorinator and low temperature pasteurization in field testing, we recommend that the project be continued with efforts focused on developing distribution channels for bringing these interventions to markets. What other lessons were learned? From our limited user research, we observed local cultural behaviors that impacted milk contamination and were not previously noted in literature:

• When milking, farmers’ hands often become slippery. To counteract this and provide friction to improve grip on the cows’ teats, farmers often tap their hands in the dirt below the cow. This tapping introduces additional bacteria to the milking process.

• Farmers were well aware that it was necessary to wash their storage containers and they did. The most common practice is to rinse a cup with soapy water or shake the soapy water in a container. The farmers’ inability to thoroughly clean the containers is due to the lack of clean water and, in the case of jerrycans, the geometry of the vessels.

• Some farmers told us that they washed their milk storage vessels with urine. Urine can act as a mild astringent, but does not provide any real level of disinfection.

• Although directed by extension workers as to the sanitary care of cows, our team found that basic steps such as cleaning the area where the cow is kept and tying its tail were not frequently done.

• As mentioned earlier, our most insightful lesson was identifying plastic jerrycans as being the main contamination point in the stakeholder chain. Although there are aluminum storage vessels that are easier to clean, they cost $70-‐$100 and are not affordable to farmers. The low cost of the plastic jerrycans at $2 suggests that these storage vessels will continue indefinitely to be the primary mode of milk storage and transport.

VI. Challenges This project had a number of challenges with technology development, particularly related to the UV-‐C system. First, the UV-‐C system faced several functional challenges relative to the problem. We were unable to achieve high net disinfection levels in raw milk using the UV-‐C system’s reduced flow rate with low-‐energy requirements. The higher energy requirements

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increased the cost of the technology to $300-‐$380 per unit, putting it out of the reach of our target small-‐holder farmers. The central technical problem is that fresh milk has a layer of cream that forms at the top of a container and this layer hinders UV-‐C penetration, which was not predicted in laboratory testing. To overcome this, it is possible to vigorously mix or stir the milk to “homogenize” it, but doing so increases the cost and size of the system as well as the energy required. Furthermore, UV-‐C systems are fairly sensitive to operating conditions. For example, they require somewhat clean environments and a stable even surface to operate effectively. The UV-‐C systems we tested in the field in August 2009 did not function properly; we later determined that this was because they could not be tilted more than 5º in any direction. VII. References FAO (2004). Milk and Dairy Products, Post-‐Harvest Losses and Food Safety. FAO,

accessed: 5 March. Lore, T. (2004). Synthesis Report. Rome, ILRI. MSN UK (2010). Weather Averages (Kenya, Uganda). Foreca, database on website,

accessed: 5 March 2010.

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