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Lab reports 1-7

DFM 357: Experimental Foods

Cassandre Miller

Lab # 1 - Basic Techniques and Measurements

9/6/13

Lab Conditions:

Though, there were no unusual conditions occurring within the lab, my partner and I had to use

rice flour as opposed to Bread flour and cornmeal in place of AP flour due to complications of

Celiac Disease. This more than likely played a role in the weight of the sifted trial. Additionally,

the trials that called for AP flour, cornmeal was used instead which has a significantly greater

weight and surface area than rice flour. These replacements could greatly change the intended

outcome of the experiment.

Purpose:

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The purpose of this lab was to compare and contrast measuring tools and methods along with

how an ingredient will change the method of measurement as well. The weight and accuracy

will change as the method of measurement and ingredient changes.

Four different measuring techniques were used, sifted, unsifted, packed, and spoon poured.

Along with the variety of measuring techniques were the ingredient variants such as, rice flour,

cornmeal, water, brown sugar, granulated sugar, Crisco, oil, butter, table salt, kosher salt and sea

salt.

Procedure:

Each ingredient was measured into the specified measuring tool, 1 cup, ¼ cup, or teaspoon. The

measurements were performed as instructed per the table then the weight was calculated via use

of a digital scale. The different flours were placed in a 1 cup measurement by spoon and at times

were leveled off with a straight edge such as a knife. The brown sugar was placed into a ¼ cup

via the use of a spoon as well, and was additionally either packed and tapped into the cup, or

lightly filled and shaken. The granulated sugar was measured similarly, though because it is not

as moist as the brown sugar, packing was not required. Hydrogenated fat or Crisco was

measured via ¼ c as well. Because the hydrogenated fat is solid, it needed to be packed into the

cup to fill any possible air pockets. Similarly, butter as a solid fat, needed to be packed so the

cup was devoid of air. Oil was poured into the cup and easily measured and weighed. The salts

then were then measured via a standard teaspoon and weights were recorded.

Results:

See appendix for Lab #1.

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Discussion:

The main focus during this experiment seemed to be on the method the experiment is

conducted. As an introduction to Experimental Foods studies, this is an important area to

observe as a student as it will affect any future cooking experiments. The method of measuring

the flours, i.e. by spoon and leveling off or sifted versus unsifted flour were provided as

examples of independent variables because they were part of the actual experiment. However,

the reason why others conducting the same experiment may have collected varying data could be

due to extraneous variables, or a “variable that is not intended to be part of the experiment”

(McWilliams, Margaret. Foods: Experimental Perspectives. p 33.) These variables could be the

size of spoon used to place the flour into the cup or perhaps any accidental contaminants in the

flour such as sugar or salt. These could be potentially eliminated from the experiment if

instructions are put in place to ensure the extraneous variables are controlled. This could be

done by creating a standardized experiment and specifying the method so precisely that any

potential extraneous variables would be removed. The book explains that even mixing

techniques should be described in great deal so the same result would occur each time. In

addition to the same mixing techniques, the type of utensil or tool used for stirring and even the

amount of strokes made should be recorded to create a standard.

The lack of standardization could explain the varying results obtained during trials 1-5.

For example, the type of flour used changed the weight drastically. Furthermore, using sifted or

unsifted flour also varied the weight. Although the weights varied frequently, trials 4 and 5 had

more detailed instructions and results varied less. The same occurred with trials 7-9, though the

accuracy of the measurements in trial 9 with granulated sugar could be attributed to the particle

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size and weight of the sugar. While instructions for measuring trial 9 were not as detailed, white

sugar is dry and cannot be aerated like flour thus possibly contributing to its accuracy. Trials 10-

12 measured the weight between hydrogenated fat, oil and butter. The butter and hydrogenated

fat were similar in weight because they were solid fats whereas the oil weighed less. One notable

issue within trial 12 however, was the fact that the butter was cold and created air pockets within

the cup, making the weights less accurate. It is because of these noticeable issues between

varying weights or measurements that standardized recipes are made, and methods are created to

increase the likelihood of repeating the same result.

References:

McWilliams, Margaret. Foods: Experimental Perspectives. 7th Edition. Pearson Education, Inc.

Prentice Hall. 2012. (p. 33)

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Lab 2: Sensory Quality

9/13/13

Lab Conditions:

No unusual conditions

Purpose:

The purpose of this lab is to evaluate combinations of primary tastes as well as how color may

affect the flavor. Additionally, the experiment is to recognize and identify the effects one taste

has on another either as flavor inhibitors or flavor enhancers.

Procedure:6

Solutions were prepared prior to entering the lab. Each station samples used randomized

numbers to ensure objectivity. Different types of evaluation tests were used per station such as

triangle, duo-trio and paired comparison. Small cups were placed at each station for pouring the

samples. Only about a teaspoon per sample was required for tasting and evaluating. Once the

samples were tasted, each were compared not only against each other but also placed into a chart

identifying the sample as either no difference, less sweet, less salty, more salty, etc. One of the

final tests was to see if color effected flavor. Samples of lemonade were colored with food

coloring such as green, orange and blue, then specific flavors were to be described to each. Once

all evaluations were made, a key was posted to determine if flavor receptors were attuned to

differences to the primary tastes.

Results:


Discussion:

Flavor is an important aspect of food and how different primary flavors blend can affect

what ingredients are used to develop a recipe. Additionally, certain ingredients added may

enhance or inhibit other tastes which can also affect the overall quality of a food. The olfactory

receptors in the nose receive odors which contribute to the overall flavors delivered to the taste

buds in the mouth. This is why colds may affect or change the taste of food. (McWilliams,

Margaret. Foods: Experimental Perspectives. p 46-47.)

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The first test was to identify the primary tastes which are bitter, sour, salt, sweet and

umami. If these tastes were answered correctly, more than like the nasal passages were clear and

no extraneous factors were affecting the taste receptors.

The next test performed was a paired comparison test or, a type of difference test where a

characteristic of two samples are to be evaluated and one with stronger characteristics is to be

identified (McWilliams, Margaret. Foods: Experimental Perspectives. p 57.) In this test, also

known as series B, sample #293 was sucrose and #142 was sucrose and citric acid. Sample #142

was supposed to be sweeter, however no difference was found by the taster. This could be due to

a variety of factors. One factor could be that the citric acid was not used as an effective flavor

potentiator and did not enhance to subthreshold level of the taster.

Series C compared the effect of salt on sweetness of a solution via triangle sensory test.

Triangle sensory test is a difference test where three samples are presented, two of which are the

same and the odd or variant sample is to be identified. All three samples are assigned random

numbers and presented at the same time so results are objective (McWilliams, Margaret. Foods:

Experimental Perspectives. p 58.) In this experiment, all three samples had equal parts of sugar

and water but one had salt added. Salt is considered to be a flavor enhancer of sweet, meaning

that it should improve or enhance the sweetness of the solution without adding a distinctly salty

flavor (McWilliams, Margaret. Foods: Experimental Perspectives. p 49.)

The next experiment, series D compared the effect of sugar on saltiness by using a paired

comparison sensory test. As previously explained, a paired comparison test is to determine if one

sample is stronger than the other. The solutions of these two samples were assigned the same

solution of salt and water, however one sample had sugar added to it. Sugar is considered to be a

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mild flavor inhibitor of salt, meaning that it blocks the taste perception. However, it is not a full

inhibitor of salt as the salt can still be tasted at threshold level, or at a level that is barely

detectable (McWilliams, Margaret. Foods: Experimental Perspectives. p 47.) Series E was a

similar test using paired comparison as well but with a citric acid solution and one with the

addition of sugar to determine that sugar decreases sourness. Finally, series F the same

experiment was conducted again. However, this time a caffeine solution was used along with

sugar to determine how it affects bitterness. Again, sugar was found to mildly inhibit the

bitterness of the solution.

Series H was performed and evaluated to determine the effect of above threshold levels

on salt on sweetness. This trial used the duo-trio test for objectivity where “two samples are

judged against a control to determine which of the two samples is different than the control”

(McWilliams, Margaret. Foods: Experimental Perspectives. p 58.) In this instance, the sample

with more salt did not seem sweeter. Once the salt was above threshold all that can be tasted is

the salt and the sugar is more of the flavor inhibitor. It makes the salty flavor milder however the

solution is not sweet and confuses the taste receptors.

Experiment, series I studied the effects of processing on the flavor of lemonade using the

consumer preference hedonic scale. A consumer preference hedonic scale is a pleasure scale

rating food characteristics, usually using a numbered system of 1-10 or 1-5 etc. 1 is the ranking

for dislike and the higher the number goes, the greater the enjoyment or satisfaction. If the

numbered scale is not used, words such as dislike extremely, neither like or dislike, and dislike

extremely are applied instead. (McWilliams, Margaret. Foods: Experimental Perspectives. p 64.)

The samples were tasted and found to increase in quality from frozen being the least liked, dry

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mix being somewhat liked and fresh being the most liked. The interesting part about this test is

that, other than it being subjective to the taster’s preferences, the expected results were not

entirely achieved. One might suspect that fresh lemonade would receive the highest score,

however powdered lemonade is the most processed and was enjoyed more than the frozen

version. This could just be a case of the taster’s preference for a certain brand of powdered

lemonade or sweetness.

One of the most interesting aspects of series J experiment or the effect of color on flavor

is how the color actually does change perception. Vision is usually the first receptor used to

determine flavor, characteristics and quality of a food. It can have a strong impact because it

links what is being seen to memory gained from prior experiences so some flavor is to be

assumed. (McWilliams, Margaret. Foods: Experimental Perspectives. p 50.) Something such as

a glass of a green liquid could be linked to memory that green usually means lime flavored. In

this trial, the visual senses confused the pallet and green was found to have almost a lime flavor,

and blue was found to have a slight bitter aftertaste. It is interesting that both yellow and pink

were found to taste like lemon because they are colors usually found in artificial lemonade.

The final test, series K was on the effect of genetic predisposition on tasting PTC or

bitterness. Unfortunately, the bitterness sensation was intense and lasted a long time. This is a

genetically inherited phenomenon, and some say attribute to a person being a “supertaster.”

Supertaster is another word to describe someone that is particularly sensitive to tastes. They

generally have more taste buds than others which subsequently means that the more taste-buds a

person has, the more intensely flavors are perceived. (“BBC - Science & Nature - Human Body

and Mind - Science of Supertasters,” 2013.)

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References:

“BBC - Science & Nature - Human Body and Mind - Science of Supertasters,” 2013.

http://www.bbc.co.uk/science/humanbody/body/articles/senses/supertaster.shtml.


Prentice Hall. 2012. (p. 46-47)













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http://www.bbc.co.uk/science/humanbody/body/articles/senses/supertaster.shtml

Lab 3: Sugar Solutions; Crystalline Candies

9/20/13

Lab Conditions:

Most conditions were constant, however due to complications of Celiac Disease samples were

tasted by other participants, so evaluation on consistency and flavor were subjective.

Purpose:

The purpose of this lab is to distinguish the effects of temperature, beating, protein and fat on a

crystalline or amorphous candy. The purpose is also to show the difference between the structure

of crystalline and amorphous candies.

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Procedure:

Each station was assigned a different type of candy to create. Ingredients were to be mixed and

heated to a specified temperature, depending on the recipe. In this particular case, lollipops were

made. First, the ingredients: sugar, corn syrup and water were placed in a nonreactive pot and

heated to extreme crack stage, or 310 F. It was important to take care and remove any crystals

that developed on the sides of the pot to ensure the solution does not become disrupted. The next

important part of developing the candies is to cook it very slowly towards the end so the solution

does not burn. Once the sugars are cooked to extreme crack phase, they are removed from heat,

and then flavoring and food coloring are mixed in. Finally, the hot liquid was dropped one

tablespoon at a time onto a non-stick, oiled surface. While the drops were still soft, toothpicks or

lollipop sticks were pressed into them so they could be held. The lollipops were removed from

the surface before completely cooled to prevent breaking or cracking.

Results:

See appendix for Lab # 3A.

Discussion:

Fondant is a type of crystalline candy that is made with sugar, water and corn syrup then

is aerated and beaten until it becomes pliable and almost like sticky dough. When a mild acid is

used like cream of tartar to achieve inversion, and a smoother product can be made.

(McWilliams, Margaret. Foods: Experimental Perspectives. p 149.) Another way this can be

achieved is by using corn syrup instead of cream of tartar because it is already hydrolyzed into

fructose and glucose (an inverted sugar.) While both variations #2 and #3 resulted in a smooth

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product, the fondant using cream of tartar runny and darker. The runny texture could be because

the product was not cooked long enough for inversion to occur, however it was cooked long

enough for it to begin browning. When an acid is used, the product needs to be cooked longer

for a reaction to take place whereas with corn syrup, the inverted sugar is already present in the

mixture. In addition to temperature and addition of an acid affecting the end product, beating

temperature can also affect the end product. According to my results both b and c resulted in a

smoother, moldable texture. However, trial A was beaten at 70 C, and resulted in a slightly

firmer consistency but spongier texture whereas trial C at 40 C was softer in consistency but

harder in texture. It seems that there is a happy medium in between the two temperatures to

reach a moldable, light and smooth product.

Fudge is another type of crystalline candy where milk or cream is added instead of water.

Milk and cream not only add flavor but it also adds fat which promotes a creamier, smooth

texture because it interferes with the formation of crystals, the same is true with a protein like

egg whites (McWilliams, Margaret. Foods: Experimental Perspectives. p 150.) As with fondant,

beating temperature and time does effect the smoothness of the fudge, however in this instance,

the beating higher beating temperature of 113 F made a creamier product rather than the lower

temperature of 104 F. Additionally, texture was affected by the cooking temperature so it would

seem that the more saturated the mixture became, the grittier the end product was. This could be

due to the interrupting agents in the sugar solution. The higher the temperature, the more

moisture was removed; therefore the solution would become super saturated. However, super

saturated solutions are less stable and can burn more easily. The fudge made in the microwave

did end up being burnt and gritty most likely related to unmonitored temperatures. The fudge

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and sugars may end up being heated to extremely high temperatures (202 F), burning the fats and

sugar.

In the final observation amorphous candies such as caramels, peanut brittle and lollipops

were made. High temperatures and “interfering agents” were used to interrupt the crystallization.

When amorphous candies are made beating is not necessary because the solutions do not become

super saturated. Milk fats like cream or butter are added in a recipe like caramels so

caramelization can occur and make an overall smooth product. Evaporated milk generally has a

higher fat content which should result in a smooth, gooey caramel, however in this trial light

cream resulted in a higher quality caramel. An error must have occurred with those performing

the experiment through unmonitored time and temperature variables. The boiling temperature of

each candy varied and therefore resulted in a more saturated solution of sugar and harder

“crack.” Peanut brittle had the most interfering ingredients and while the amorphous candies do

not require beating, peanut brittle needs to be aerated. Aeration in peanut brittle occurs from the

addition of baking soda and heat in a reaction. Once the baking soda is added, the candy mixture

starts to bubble and then almost immediately harden.

References:


Prentice Hall. 2012. (p. 149.)



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Lab #4: Thickening Agents

9/27/13

Lab Conditions:

No unusual conditions. Constant conditions.

Purpose:

The purpose of this lab is to compare thickening ability of a variety of starches. It is also to

compare the freezer and thaw stability of each flour or starch. A further objective of the

experiment is also to experience how the addition of sugar may affect freezer thaw stability and

thickening ability of a starch. The importance of the experiment is to observe at what

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temperature “pasting” begins, as well as gelation. This could determine the content of amylose or

amylopectin available in the different starches, which would further determine their uses.

Procedures:

Each station was provided a different starch or flour to use in this experiment. However, the

procedure was the same as the variable in the experiment was the starch. Three trials were

performed, each with 2 tablespoons of starch (in this case, sorghum flour), and one cup of water.

One trial was tested without the addition of sugar. A second trial required the addition of 2

tablespoons of sugar, and a third with 6 tablespoons of sugar. Each trial was heated until boiling

and starches began to thicken in consistency, then they were cooked on low for an additional 5

minutes, stirring when necessary. After these steps were completed, ½ of each trial was set aside

and frozen. Temperatures at which each trial began to thicken and gelatinization occurred were

recorded in a table. Qualities such as thickness, transparency, and consistence as cooked and

after freezing were observed and evaluated using the hedonic scale.

Results:


Discussion:

Different starches have varying degrees of gelatinization before and after the addition of

sugar. Some starches are really opaque whereas others like tapioca are fairly clear. Furthermore,

corn starch and potato starch seemed to be the most resistant to gelatinization and required the

highest temperatures before thickening. Corn starch, wheat flour, rice flour and oat flour also had

the smoothest consistency, however wheat flour has a lower starch content and should not have

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resulted in a smooth mixture. However, the addition of sugar made a runnier, less consistent

solution and affected the product’s freeze thaw stability. Most starches without sugar that were

frozen were in a solid piece whereas the mixtures with sugar usually thawed faster and the

consistency was grainier. The consistency of each solution could be attributed to the content of

amylose or amylopectin present within a starch. Some tubers and cereal grains such as rice, corn

and wheat have the highest amylose content whereas tapioca has the least amount. Amylopectin

can also be found within tubers and some cereal grains. Due to its large molecule size, and the

low starch content of both amylose and amylopectin each mixture containing these polymers

were less consistent and grainy. (McWilliams, Margaret. Foods: Experimental Perspectives. p

172.)

References:



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Lab #5: Fiber

10/04/13

Lab Conditions:

Due to complications related to Celiac Disease, texture and flavor were recorded via other test

participants and results may be subjective.

Purpose:

The purpose of this lab is to observe and experience the effect of a variety of starches and flours

in different recipes. Subjects will observe how different starches or flours effect cooking time,

moisture, appearance, consistency, texture and flavor.

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Procedures:

Recipes were provided and followed for making cookies or muffins, starches varied per station.

In this case chocolate chip cookies were made with sorghum flour. The oven was preheated to

350 F, while the ingredients were prepared. The sorghum flour was sifted and set aside for later

use. Then, butter, sugar, egg, baking soda, salt and vanilla extract were creamed together via a

handheld mixer for approximately 2 minutes on medium speed. The flour was gradually added to

the mixture along with the chocolate chips and blended for an additional two minutes. For

constant results, the dough was separated into 6 equal portions using a scale. Each measured

cookie was then placed on a baking sheet lined with parchment or wax paper. Cookies were

baked for about 8 minutes or until golden brown. Cookies were removed from the oven and

cooled. The baking time was observed and recorded. Additionally, each trial was inspected for

color and appearance, texture and flavor.

Results:


Discussion:

The effect of starch on a recipe can vary greatly from differing in flavor, appearance or

texture. During this lab muffins and cookies were prepared using various flours with fiber added.

Cookie sample 923 had the best appearance, texture and flavor whereas muffin sample 183 also

had the best appearance, texture and flavor of its category. This was an interesting discovery

because sample 923 used 47g of inulin and sample 183 used 43 g of dextrin. The reason this is

interesting is because Inulin is a soluble fiber with no additional flavor and dextrin is only

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slightly soluble, slightly sweet and has limited thickening ability. The two fibers are fairly

different yet they were found more desirable in different recipes. (McWilliams, Margaret.

Foods: Experimental Perspectives. p 226-133.) Inulin makes more sense in a muffin because of

its solubility. It absorbs moisture while not adding flavor. In fact, many food manufacturing

companies add it to breads and cakes to increase fiber. (McWilliams, Margaret. Foods:

Experimental Perspectives. p 226.) Additionally, dextrin was successful in the cookie recipe

because it is slightly sweet but also less soluble. This added texture and crunch to the cookie

while still attracting enough moisture to be soft in the center. Most of the fibers added did not

have a flavor except for cookie sample 353 using fiber F which had a slight fishy taste. The

fishy taste usually is attributed to soy bean or seed oils so in this case it could easily be assumed

that flax seed was the fiber used.

This experiment allowed subjects to explore what the best fiber is for baked products

while adding a slight health benefit of whole grains. This is important because both soluble and

insoluble fibers bind to cholesterol and excrete it in waste, successfully reducing serum

cholesterol levels. (McWilliams, Margaret. Foods: Experimental Perspectives. p 223)

References:




Prentice Hall. 2012. (p. 226-133.)



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Lab #6: Fats and Oils

10/11/13

Lab Conditions:

No unusual conditions. Constant conditions.

Purpose:

The purpose of this lab was to experiment with the use of different types of fats in pastry and

how they affect cooking time, color, flavor, and tenderness. Another purpose of the lab was to

experiment with the use of fats in emulsions and how different emulsifiers affect its stability in a

“permanent emulsions” such as mayonnaise. (McWilliams, Margaret. Foods: Experimental

Perspectives. p 119)

Procedures:

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I was not present for this lab, however when I have made pastry before, I usually choose a solid

fat to cut into a mixture of flour and salt. Usually the fat is cold or cold water is added, such as

in this case. The pastry is then baked at a high temperature, browning the flour. In this

experiment a variety of fats were supplied to be used for making the pasty such as, shortening

(the control group), lard. Margarine, butter, vegetable oil, soft margarine, and reduced fat

margarine. In addition to varying the types of oils or fats used three types of flours were also

used such as whole wheat flour, bread flour or cake flour.

Results:

See appendix for Lab #6

Discussion:

Fat is successful as an emulsifying agent and promotes tenderness and browning of

pastries. Solid fats like shortening and margarine are both hydrogenated fats, stable at room

temperature. (McWilliams, Margaret. Foods: Experimental Perspectives. p 258.) These solid fats

usually produce tender, flakey pastries which could be partly because of their altered melting

point and lower smoke point. A lower smoke point allows a product to brown at a lower

temperature while still cooking properly. Most pastries are cooked at approximately 300-350 F

which is close or just below the smoke point of both fats. (McWilliams, Margaret. Foods:

Experimental Perspectives. p 246-247.) Surprisingly one of the least tender samples of pastry

made also used margarine but it was with soft tub margarine whereas the tenderest sample was

stick margarine. This could be due to an extraneous variable such as an error on temperature,

underestimated time, or possible a malfunctioning stove. In fact, the fat that should have

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produced the crunchiest texture of dough is the reduced fat margarine. Because it the amount of

fat was reduced in that sample, the cooked pastry would not have resulted in a tender dough due

to the overall fat content being lower than regular margarine or shortening. In addition to the

type of fat affecting the tenderness of a pastry, the type of flour used can also change the color,

flavor and texture. The sample using cake flour actually resulted in a product that was very

tender. Cake flour has a low protein content and higher starch content than bread flour or whole

wheat flour. This allows more moisture to be absorbed by the starch molecules.

Fat used in conjunction with an emulsifying agent can result in a permanent emulsion as

with mayonnaise. According to McWilliams’ book, an emulsifying agent “consists of both polar

and non-polar groups and thus has some attraction toward both phases of the emulsion.” This

usually results in a “power struggle” between the two phases. (McWilliams, Margaret. Foods:

Experimental Perspectives. p 119.) In a water in oil emulsion, water droplets are dispersed

throughout an oil, i.e. butter. However in an oil in water emulsion, oil droplets are dispersed in

water, i.e. mayonnaise. (McWilliams, Margaret. Foods: Experimental Perspectives. p 118.) Both

emulsions are considered colloids because the mixture is homogenous and has a continuous and

discontinuous phase. (McWilliams, Margaret. Foods: Experimental Perspectives. p 116.) When

creating a colloidal mixture like mayonnaise salt, mustard, paprika and other dry agents are

added for flavor and moisture retention. The egg yolk is used as the emulsifying agent within the

mayonnaise because of its unique properties of containing lecithin and protein. The lecithin in

the egg yolk makes one of the best emulsifiers because of its lipophilic and hydrophilic

properties. In fact, it is the lipophilic property of an egg yolk that can save mayonnaise when it

“breaks.” By adding the egg yolk, the excess oil will be attracted to the egg yolk. (McWilliams,

Margaret. Foods: Experimental Perspectives. p 119.)24

References:










Prentice Hall. 2012. (p. 246-247.)



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Lab 7: Milk Proteins

10/25/13

Lab Conditions:

Due to complications of Celiac Disease, flavor and consistency/tenderness were recorded based

on other participant’s experiences and may be subjective.

Purpose:

The purpose of this lab is to experiment with different types of milks that have varying protein

and fat content and their ability to make cheese through a reaction catalyzed by an acid (vinegar)

or an enzyme (rennet).

Procedure:

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Each station was assigned a specific milk to make both cottage cheese and ricotta. In this case, 1

cup of coconut milk was used in combination with 1 cup of non-fat cow’s milk. First, to make

basic cottage cheese, a rennet tablet was dissolved in one tablespoon of warm water while the

milk combination was heated to 98.6 F (37 C) in a non-reactive pot. Once the tablet was

dissolved, it was added to the milk mixture and allowed to stand for one hour. After one hour,

the curds should be set and the cottage cheese poured into a double layer of cheese cloth to drain

any excess whey.

The next experiment was to make basic ricotta cheese. The milk mixture was heated in a

nonreactive pot to 181.4 F (83 C) until almost boiling and tiny bubbles begin to rise. Once the

temperature is at 181.4 F, the pot is removed from heat and vinegar (1 T) is immediately added

and stirred gently for one minute. The clotted mixture is poured into a double layer of cheese

cloth and tied into a ball and allowed to drain for at least 15 minutes without squeezing. Both

cheeses were set aside for testing and evaluation of flavor and tenderness. Whey removed from

the cottage cheese was measured to determine how much product (curds) was produced.

Results:

See appendix for Lab # 7 and #8.

Discussion:

Either an enzyme or acid can curdle the protein or casein in dairy, leaving only the liquid

whey, which also is high in protein. Rennin is an enzyme derived from a calf stomach that can

be used to curdle milk by counter acting and removing the protective enzyme casein naturally

has. The protective property casein has normally prevents the micelles from being attracted to

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each other, by removing the protective property this allows the micelles to aggregate and

gelation can occur. (McWilliams, Margaret. Foods: Experimental Perspectives. p 299.) When

using rennin to make cheese, some precautions must be made to ensure that curds will form.

Firstly, rennin increases the acidity of milk, if the mixture sets overnight, this can cause the

cheese to ferment. Additionally, rennin is heat sensitive and if it is heated and dissolved for

longer than 45 min to an hour, the enzyme will weaken in potency, which could inhibit the

formation of the curd (Haug, Catherine. “Cheese Making with Kalispell Kreamery Milk « The

EssentiaList,” April 10, 2011.) After the rennin and milk mixture sit for about an hour, the curd

is cut to ensure that the casein did form a gel. Cutting the curd also allows the whey to be

drained. Rennin coagulated milk actually results in a product that is high in riboflavin. While the

curd contains riboflavin, the whey also does, along with some water soluble vitamins and

minerals. In fact, it seems as though the whey is even richer in nutrients than the actual curd.

Whey is so high in nutrients and protein that some manufacturers dehydrate it and form a powder

that can make high protein, nutrient rich meal replacement shakes.

When the experiment was conducted, both animal and non animal sources were used to

form both cottage cheese and ricotta. Both the ricotta cheese and cottage cheese with the best

textures were formed from or in conjunction with animal sources. This could be due to the

higher protein content of the animal milk. However, some dairy sources such as lactose free milk

did not form a curd, which could suggest some error in the experiment. As previously stated,

rennin is heat sensitive and the longer it is dissolved, the weaker the enzyme becomes. Rennin’s

heat sensitivity could have contributed to several errors in the cottage cheese experiments where

the curd did not form when it should. Additionally, the milks used with the higher fat content

contributed to a silkier, creamy texture and buttery flavor. The non-fat milk resulted in a more

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plastic-like, chewy texture almost that of heated mozzarella cheese, with little to no flavor. The

interesting part regarding this issue however is that the cheese made with coconut milk and non-

fat milk combined and made a smooth and silky ricotta and cottage cheese. The conclusion that

can be derived from this combination is that the protein content of the non-fat milk allowed curds

to be formed and the fat of the coconut contributed to a smoother, silky texture and creamy,

sweet taste. For most of the samples, the ricotta was grainier and had smaller curds, though on

average the samples were creamier in texture than the cottage cheese. Additionally, some

samples of the ricotta were sour because the vinegar added flavor whereas the rennet from the

cottage cheese did not add any distinct taste.

The overall experience brought to light the sensitivity of using rennet and the

considerations necessary in order to properly form curds. It is important, just as with baking to

treat cheese making as a science and watch time, temperature and measurements. It is also

important to consider fat and protein content when choosing a dairy product to make cheese.

References:

Haug, Catherine. “Cheese Making with Kalispell Kreamery Milk « The EssentiaList,” April 10, 2011.

http://essentialstuff.org/index.php/2011/05/26/Cat/cheese-making-kalispell-kreamery-milk/.


Prentice Hall. 2012. (p 299.)

29

http://essentialstuff.org/index.php/2011/05/26/Cat/cheese-making-kalispell-kreamery-milk/

APPENDIX

Labs #1 -#8

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