Food Science: Dairy
Forrest Schultz, PhD
Wisconsin State Science Olympiad Director
Director, 2016 Science Olympiad National Tournament
Chemistry National Rules Committee
Chair, Department of Chemistry and Physics
University of Wisconsin-Stout
Division B Food Science: Dairy
1
Science Olympiad 2015-2016
Please Note
•
This recommended guidance suggests only one of a
variety of ways for teams to record their mass that an
Event Supervisor may use. Teams may be asked to
submit a sample for massing using a variety of
procedures that teams need to verify with their
Regional or State Director/Event Supervisor.
Division B Food Science: Dairy
2
Science Olympiad 2015-2016
Event Process
•
Learn about making ice cream, curds and butter
•
Practice and experiment making these products while
developing a notebook
•
Attend tournament and take written test and make products,
impound notebook and bring supplies
•
HAVE FUN!!!!
Division B Food Science: Dairy
3
Science Olympiad 2015-2016
Event Parameters
Comments/Suggestions
Students: Each team must bring safety equipment, a writing
implement, a calculator and the materials listed below needed to
prepare ice cream and perform the curd mass analysis and/or the
milk fat mass analysis. Each team may bring 5 pages (both sides)
containing information in any form from any source (sheet
protectors are permitted). Teams must bring only plastic bags,
cups, spoons, graduated cylinders, 500-600 mL plastic container
with lids, cheesecloth, beakers, pH paper, paper towels, gloves, and
a towel. Glove types must be of competitor’s choice.
Supervisors: will provide necessary milk products (any type of milk
may be provided including powdered), salts, lemon juice, vinegar,
ice (if necessary), thermometers, or other reagents or equipment to
complete the experimental activities. The provided quantity of milk
product will be between 125 and 150 ml depending on which Lab is
being used. The amounts provided shall be the same for each
student.
Teams are to bring all of the equipment needed, Event
Supervisors will provide things like balances.
Lots of paper towels may be needed.
Gloves (winter type or lab hot/cold) are REQUIRED for ice
cream production
Event Supervisors are to provide all necessary milk
products.
For the making of ice cream, anticipate 1-2 lbs. of ice for
each team
Safety Requirements: Students must wear goggles, an apron or a lab
coat, gloves (for ice cream Lab only), and have skin covered from
the neck down to the wrist and toes. Long hair, shoulder length or
longer, must be tied back. Students who unsafely remove their
safety clothing/goggles or are observed handling any of the
material or equipment in an unsafe manner will be disqualified from
the event.
Eye Protection CATEGORY C
• Description: Indirect vent chemical/splash protection goggles. These seal tightly to the face completely around the eyes and have indirect vents constructed so that
liquids do not have a direct path into the eye (or no vents at all). If you are able to see through the vent holes from one side to the other, they are NOT indirect vents
• Corresponding ANSI designation/required marking: Z87 (followed by D3 is the most modern designation but, it is not a requirement)
• Example: Indirect vent chemical/splash protection goggles
Notes:
1. A goggle that bears the Z87+ mark and is an indirect vent chemical/splash protection goggle will qualify for all three Categories A, B & C
2. VisorGogs do not seal completely to the face, but are acceptable as indirect vent chemical/splash protection goggles
Division B Food Science: Dairy
4
Science Olympiad 2015-2016
What is Milk?
A mixture of Fat, Protein, Carbohydrate, Minerals, and Vitamins.
The fat and protein exists as a colloidal suspension in a matrix of
water which contains water soluble carbohydrate and minerals.
Milk under a microscope and magnification of 800x
http://dairydream.blogspot.com/2012/08/pasteurized-vs-raw-milk-under-microscope.html
Division B Food Science: Dairy
https://www.uoguelph.ca/foodscience/book-page/milk-structure
5
Science Olympiad 2015-2016
SEM* image of dried Milk
This is a fantastic image that shows the large colloidal structure of the milk fat globules and the smaller colloidal structure of the milk proteins
casein. Minerals and vitamins are much smaller and cannot be seen in this image. Calcium minerals are associated with the proteins, while
vitamins A and D are fat soluble vitamins and are within the fat globules. Even bacteria can be seen!
Streptococcus
Casein
Fat Globule
*SEM-scanning electron microscopy
Division B Food Science: Dairy
6
Science Olympiad 2015-2016
Recommended Websites on Milk
specific Information and notebook standard
National SO Event Site SO
experimental form are found here.
https://www.soinc.org/food_science_b
Excellent Scientific and Experimental Overview
https://www.uoguelph.ca/foodscience/book-page/dairy-science-and-technology-ebook
https://www.ilri.org/InfoServ/Webpub/fulldocs/ilca_manual4/Milkchemistry.htm
Applications and General Knowledge
The Overview and General
Knowledge links are excellent
study resources for the
experimental tasks and written test
components of the event.
http://www.eatwisconsincheese.com
http://www.healthyeating.org/Milk-Dairy/Scientific-Research.aspx
http://www.ift.org/knowledge-center/learn-about-food-science.aspx
Division B Food Science: Dairy
7
Science Olympiad 2015-2016
Common Milk Products
Definitions of milk products:
http://www.idfa.org/docs/default-source/resource-library/industry-facts/248_definitions-of-milk-products.pdf?sfvrsn=2
Whole Milk: 4%
2% Milk: 2%
Skim Milk: <0.5%
Half-and-Half: 12% fat
Light Cream: 20% fat
Light Whipping Cream: 30% fat
Whipping Cream: 35% fat
Heavy Cream and Heavy Whipping Cream: 38% fat
Fresh Cheeses:
http://www.foodsubs.com/Chefresh.html
Division B Food Science: Dairy
8
Science Olympiad 2015-2016
Science of Milk Particles
The main proteins and fats in milk consist of rather large particles referred to as colloidal particles. These particles have a
negative charge associated with them at the pH of milk which is typically just above 7. This charge characteristic of these
particles keeps the particles separated and suspended in the water of milk. If it were not for this charge, the particles
would quickly settle out of the water. For example, fat particles would rise to the top, since their density is less than
water and the molecules are not miscible(soluble) in water. There are some proteins that are water soluble and do not
exist as these colloidal particles, they are referred to as whey proteins. Water surrounds the particles and contains
soluble carbohydrates like lactose.
Protein
Negative charges surround
the colloidal particles
Fat
Protein
Fat
Fat
Division B Food Science: Dairy
9
Science Olympiad 2015-2016
Science of Curd Formation
When acid or H+ ions are added to milk they react with the
negatively charged molecules on the surface of the colloidal
particles. This acid-base reaction neutralizes the charge. When
the particles no longer carry a charge, they no longer repel one
another and collapse into a precipitate. This precipitate is what we
call a curd. The acid can come from common acidic liquids like
vinegar or lemon juice. When bacteria grow they consume the
lactose in milk and produce lactic acid which also leads to the
curdling of milk. The neutralization pH is typically around 5.
Fat
acid provides H+
Protein
Fat
Fat
after acid addition
Fat
Curd
Fat
Fat
Protein
10
Division B Food Science: Dairy
Science Olympiad 2015-2016
Curds and Whey
The whey contains water
soluble components of milk,
while the large protein and fat
particles are obtained through
separation techniques to
isolate the curd. Even though
the calcium compounds in the
milk could be water soluble,
then tend to be bound to the
proteins, so the curd also
contains calcium minerals.
Since lactose tends to be
more water soluble, curds
tend to not contain a lot of
lactose.
Division B Food Science: Dairy
11
Science Olympiad 2015-2016
Curd Formation Techniques, Ideas and Comments
Filtration-paper towels work
well, cheese cloth certainly
can be used and a variety of
fabrics also work very well
and are stronger than paper
towels. Funnels are
recommended.
Pressing or Squeezing is a
common process in the
formation of cheese
products. Pressing the curds
in a cloth greatly accelerates
the removal of the whey.
Collecting the curd
precipitate can be tedious,
but a common laboratory
technique in which to
become skillful
Drying the curd formation by
continued pressing in dry
paper towel is very effective.
This can lead to a constant
mass which could be used
for scoring by an Event
Supervisor
A Cheese Ball can be
formed by the pressing
technique and lead to a ball
that can be handed to an
Event Supervisor on a
toothpick for massing, too
wet and it will fall off!
Typical milk products contain a large quantity of curd, which means that a significant amount of acid may need to be added. Prior
experimentation couple with checking of the pH can help identify the proper quantity of acid to add. Unlike some chemical reactions
with small molecules, the protein and lipid colloidal particles require some time to coagulate. The coagulation time may be a good
independent variable to explore in prior experimenting. Also, during coagulation, constant stirring may not be desired as particles
come together. More coagulation of the curd may lead to an easier and more complete separation process.
Division B Food Science: Dairy
12
Science Olympiad 2015-2016
Science Butter Formation
The fat globules have a center component consisting of a mixture of a variety of lipids. The outer layer (shown in red) is a layer referred to as
phospholipid layer. This layer surrounds the inner lipid (fat) particle and carries the negative charge. In the making of butter, the pH is not altered.
The fat globules are forced together (called churning) into larger particles of fat. As these particles continued to “smash” into one another, the
phospholipid layer breaks open and the fat molecules come together in larger particles. After continued churning, the particles become so large
that they come together has a large mass of what we call butter. The remaining liquid is called butter milk. Butter begins with cream which as a
high milk fat content. The high content is needed so that the particles can actually collide with one another in a reasonable amount of time.
Fat
Fat
Collide these violently!
Fat
Division B Food Science: Dairy
Fat
13
Science Olympiad 2015-2016
Butter Formation Techniques, Ideas and Comments
A plastic wide-mouth
container with a tightfitting top is needed. The
container needs to be
shaken violently to force
the fat globules together.
Glass jars are not
allowed since breakage
can occur.
As the cream is shaken,
a stage called “whipped
cream” occurs. This is
not yet butter. Violent
shaking is required to get
through this stage.
Division B Food Science: Dairy
The butter “ball” can then
Once the buttermilk is
be dried in paper towel
released from the cream, and then massed for
a ball of butter will exist in scoring. The butter will
the cup. The liquid
tend to stick together
buttermilk is decanted
better than the curds. But
from the butter mass.
moisture may still be
The butter can be rinsed prevalent.
with cold water.
14
With a little pressing in
paper-towel the butter
can also be placed on a
toothpick to be massed
by an Event Supervisor.
Science Olympiad 2015-2016
Science of Ice Cream
Ice cream is a mixture of milk, air and sugar.
Ice cream is not only really yummy, but it is a
rather amazing material. Ice cream has
unique material properties like being
“scoopable" while retaining its shape Unlike
butter and curds, ice cream contains much
water. This water is important as it interacts
(through hydrogen bonding) with sugar. The
water and sugar matrix along with ice
crystals gives ice cream much of its
properties. The other key ingredient is air
which leads to greater volume and desirable
characteristics we enjoy as we eat ice
cream. In making ice cream, constant
agitation of the ingredients is needed while
the temperature is lowered. Once the
temperature is low enough, the ingredients
are “locked” into a matrix as shown in the
drawing (B) and microscopic image (A).
http://g4icecreamproject.blogspot.com/2013/06/practical-4-investigating-fat-and-air.html
Division B Food Science: Dairy
15
Science Olympiad 2015-2016
Making Ice Cream
A common and simple method to make ice
cream is to mix milk/cream and sugar in a plastic
bag which is then placed in another bag with a
salt/ice mixture. This method works well, but
other methods certainly could be utilized, such as
plastic storage containers. The plastics bags can
puncture if one is not careful, especially with rock
salt. The bags will get very cold!!! Frostbite is a
concern. Teams are required to wear some sort
of thermal protection gloves.
Division B Food Science: Dairy
16
Science Olympiad 2015-2016
Written Test
TEST TOPICS:
Teams will take a written exam that covers only dairy food science
topics such as: the role of lipids, carbohydrates and proteins typically
found in dairy foods; standard labeling regulations; basic organic
reactions such as esterification, fat bonding; saturated and unsaturated
fats; chemical structure of sugars, starches, fats, and proteins; essential
fats, vitamins, proteins; how cooking changes dairy foods chemically;
allergens in dairy foods; dairy food preservation; RDA (recommended
daily allowance) of essential minerals and vitamins in dairy foods and
the consequences of not having them; freezing point depression; nondairy ‘milk’ products; lactose free milk; health benefits of dairy foods;
low fat, fat free milk; lactose intolerance; emulsification; pasteurization;
organic dairy products; casein and whey proteins; probiotics.
Teams will be provided a written test based on the
topics listed in the rules. The Recommended
Websites indicated earlier in this document are
excellent resources for the written test. Since Food
Chemistry is in the Physical Science category, a focus
should be placed on the chemistry of diary products
and the molecules contained within them.
SAMPLE TEST QUESTIONS:
i. What is the protein that is most common to cow’s milk?
ii. Does table salt or rock salt produce a greater freezing point depression?
iii.What are the chemical compositions and nutritional values of 2% milk, skim milk, halfhalf, cream and whole milk?
iv. What are the chemical structures and names of the common fats in dairy products?
v. How does soy milk compare and contrast with cow’s milk?
Division B Food Science: Dairy
17
Science Olympiad 2015-2016
Notebook
NOTEBOOK:
Prior to the tournament, teams must perform 3 or more experiments for
each of the three Lab Tasks below. These experiments must be
recorded on the Food Science Experiment Form (see on
www.soinc.org) and must be placed together in the Notebook. Students
are encouraged to do more than nine experiments, but only the first 3
for each task will be graded. Each experiment will constitute one entry
in the Notebook and each must have only one Independent Variable.
The Notebook will be impounded prior to the start of the tournament
for grading.
At the Science Olympiad website (soinc.org) under
the B/C Events menu is a link to Resources and Links
for Food Science. At this page is a link to a Food
Science Experiment Form. This form (see at left) is to
be utilized to record the results of experiments
performed by teams before the tournament. The
experiments in the notebook should be experiments,
and not just a record of making a dairy product. Many
of the aspects of the Experimental Design scoring
rubric should be considered. Things like trials and
collecting data for at least three changes of an
independent variable should be considered.
Depending on the impound procedure at a
tournament, it may be possible that teams do not
have access to these notebooks during their event.
This is where prior experimental information may
need to be included in the 5 pages of notes that each
team can bring to the competition.
Division B Food Science: Dairy
18
Science Olympiad 2015-2016
Scoring
SCORING:
High score wins. Final Score = Notebook Score + Lab Task(s) Score + Test Score - Penalties.
a. Notebook Score = Complete experiments receive up to 2 points each. Incomplete experiments receive fewer points
(maximum 18 points).
b. Lab Tasks Score = Total of score(s) of required Lab(s)
i. Ice Cream Score = 0.1 pts for each mm (rounded off) of height (e.g., Team gets 125 mm x 0.1=12.5)
ii. Curd Mass and the Milk Fat Mass Scores = Team mass/Supervisor mass x 10 (e.g., Team get 2.4g Supervisor
gets 2.5g = 0.96x10 = 9.6) (maximum 10 points each).
c. Test Score = Percentage correct/2 (maximum 50 points)
d. Penalties: Up to 10% of total possible score may be subtracted for failure to clean up as instructed.
e. Tie Breaker: Preselected questions on Test
f. Scoring Example: Notebook Score was 18, Ice Cream Score 12.5, Curd Mass Score was 9.6, Test Score
was 90%, No Penalties. Final Score = 18 + 12.5 + 9.6 + 90/2 = 85.1
Scoring is a combination off team performance on the Notebook, Written Test and Lab Tasks. The Event Rules indicate
which Lab Tasks could be performed at the tournaments. See below:
LAB TASKS: At the tournament, teams will use the provided food materials to perform the tasks. At Regionals teams will
only perform one of the tasks. At State Tournaments students will be asked to complete one or two of the tasks. At
Nationals, students will be asked to perform two or three.
As teams practice their events, it is anticipated that they will become more efficient in their experimental processes.
Division B Food Science: Dairy
19
Science Olympiad 2015-2016
Scoring - Ice Cream
The scoring of the ice cream lab task is based on the
height of the ice cream “tower” that can be formed by
the teams. Event Supervisors will make these
measurement according to a process explained to the
teams. Although ice cream can melt, it is really an
amazing material in that it holds its shape extremely
well at a variety of temperatures.
Height Measurement
Division B Food Science: Dairy
20
Science Olympiad 2015-2016
Scoring - Curds and Butter
Butter and Curd on a Stick!
The scoring for these Lab Tasks is based on a
team’s ability to properly isolate the curd or butter
from milk products. Event Supervisors may
provide guidance to a variety of ways for teams
to record their mass or teams may be asked to
submit a sample for massing by the Event
Supervisor.
One of the real aspects of cheese curds and butter is moisture
content. Moisture is an important aspect which leads to certain
characteristics for these materials that we seek in these materials
as consumers. However, this can lead to challenges in making
mass measurements of the resulting products. Event Supervisors
will most likely provide guidance at tournaments on how they plan
to gather or make the mass measurements. Experimental
knowledge and experience will be needed by teams to work with
the curds and butter. Techniques such as filtration, decanting and
drying of the products will be important.
Division B Food Science: Dairy
21
Science Olympiad 2015-2016