Embedded Files
Research Question:
Research Question:
- What experimental details are the most important when trying to accurately measure the concentration of protein in milk using microfluidic colorimetry?
- What is the concentration of protein in various commercial milks?
Learning Objectives:
Learning Objectives:
- Determine the experimental constraints necessary to make accurate colorimetric measurements using a cell phone camera.
- Evaluate the strengths and limitations of different types of standards when analyzing a complex matrix.
- Evaluate different forms of sample pre-treatment.
To Do List:
To Do List:
Step 1: Read lab background (see below), watch videos, and visit links provided on this page about the experimental context
Step 1: Read lab background (see below), watch videos, and visit links provided on this page about the experimental context
Step 2: Read procedure
Step 2: Read procedure
Step 3: Watch necessary tutorials and videos from the tutorial list below
Step 3: Watch necessary tutorials and videos from the tutorial list below
Step 4: Answer pre-lab questions
Step 4: Answer pre-lab questions
Step 5: Perform lab experiment
Step 5: Perform lab experiment
Step 6: Answer post-lab questions
Step 6: Answer post-lab questions
Watch videos on Dr. Tejal Desai, Professor of Biomedical Engineering and Therapeutic Sciences at University of California San Francisco
Tutorials to Watch:
Tutorials to Watch:
- Constructing and Using the Device
- Image Analysis Tutorials
Introduction to Food Allergies
Introduction to Food Allergies
In the US alone, 32 million people suffer from food allergies. An allergy is a chronic medical condition which causes your body to produce an abnormal reaction to a harmless substance (allergen) and can lead to death.1 Allergens can be both environmental or in food. When an allergen comes in contact with the body, its immune system views the allergen as an invader and begins to initiate processes to protect itself.1 White blood cells produce antibodies which attach themselves to mast cells and cause the release of chemicals like histamines (organic, nitrogenous compounds involved in localized immune responses).1 These potent chemicals can cause symptoms ranging from mild, like coughing or sneezing, to severe anaphylactic reactions.1 Learn more about histamine by watching this video: Histamine: The Stuff Allergies are Made of and exploring this Milk Protein and Allergy Infographic
What does it Mean to be Allergic to Cows’ Milk?
What does it Mean to be Allergic to Cows’ Milk?
Allergies to cows’ milk are when the body undergoes an abnormal reaction in response to the consumption of one of the many proteins found in the milk, like caseins, or lactalbumin. Many people assume this is the same condition as lactose intolerance, however they are entirely different reactions to the consumption of milk. Lactose intolerance is an enzymatic process which occurs in the stomach as a response to the sugar “lactose” which is present in cows’ milk.2 The involvement of the immune system differentiates an allergy to milk from lactose intolerance.2 Milk is one of the eight major food allergens identified by the FDA along with eggs, fish, wheat, soy, peanuts, tree nuts, and shellfish; it is such a common and severe allergen that any food containing even trace amounts must include an advisory label somewhere on its packaging.3 These eight allergens make up 90% of all food allergies.7
Who Suffers from Food Allergies?
Who Suffers from Food Allergies?
A global average of 2.5% of babies develop a milk allergy before the age of one.4 Fortunately, the majority of children outgrow this allergy by the age of 5.4 Approximately 1 in every 200 adults suffers from an allergy to cows’ milk. Of these cases, an anaphylactic response makes up only 0.8-9%, while the majority of cases have skin or gastrointestinal symptoms.5 There is an acknowledge lack of information regarding milk allergies, however specialists believe looking towards countries outside of the US with fundamentally different diets may be helpful in understanding the causes of allergies.5 For example, in Thailand where dairy isn’t a traditional aspect of their diet, there was found to be some correlation between women who consumed dairy during their pregnancy and their child consequently developing an allergy to milk.5 The further study of the effects of different diets can give researchers insight into potential preventative recommendations.5
Why do People Develop Food Allergies?
Why do People Develop Food Allergies?
The true underlying cause of food allergies is still undetermined by professionals, however there are many theories and studies which have been done to show correspondence with different lifestyle aspects. It is proposed that there is a genetic component, therefore some people may be predisposed to allergies, however the research on this hypothesis is limited. Another theory finds correlation between the consumption of food products by the mother specific to that region’s diet and frequent cases of allergy to that food.7 For example the US has a generally high consumption of peanuts as well as a high percentage of the population with allergies to peanuts.7 Foods like raw vegetables, certain fruits, and tomatoes are dominant in the Italian diet, therefore the rate of allergies to these foods is much higher among the Italian population.7 Additionally, Italy has a much lower rate of peanut allergies than the United States because that is not a staple in their populations’ diets.7
Allergens may be either heat resistant or nonresistant to heat, and the difference is based off of the protein structure of the allergen.7 Heat resistant allergens are linked to the amino acid order of the protein responsible for the allergy.7 This group causes most of the major allergens like peanuts, milk lactoglobulin, and egg white ovalbumin.7 These allergens will continue to affect the body in the same way even after they are cooked. Some allergens are non-resistant to heat due to the spatial structure of the protein.7 Cooking these proteins at a high temperature causes the three-dimensional structure of the protein to be fundamentally changed, therefore they do not harmfully affect the body if the same ways they would if they were uncooked.7 The allergy to cows’ milk is thought to be caused by three major proteins: a-lactalbumin, b-lactoglobulin, and caseins. There are likely other proteins which cause allergies, however these are generally the only proteins tested when diagnosing a milk allergy.6
It is important for biochemists and food scientists to be able to quantify the protein content of certain samples, especially when those samples contain allergens that can cause life threatening reactions. The total protein assay consists of an indicator for the detection of protein, tetrabromophenol blue (TBPB), citrate buffer (pH 1.8) for maintaining the constant pH, and a sample or standard. In this lab, the indicator TBPB changes color from yellow in its native acidic form to blue when bound to the amine groups of basic amino acids, such as lysine, arginine, and histidine in an acidic environment. This color shift is linearly proportional to the concentration of protein in solution over a relevant concentration range.
Figure 4. Molecular Structure of the Protein Indicator Tetrabromophenol Blue
Figure 4. Molecular Structure of the Protein Indicator Tetrabromophenol Blue
References:
References:
“Allergy Definition.” Allergy: AAAAI, The American Academy of Allergy, Asthma & Immunology, www.aaaai.org/conditions-and-treatments/conditions-dictionary/allergy.
Felson, Sabrina. “Lactose Intolerance vs. Dairy Allergy: Symptoms, Diagnosis, Living With.” WebMD, WebMD, 25 June 2019, www.webmd.com/digestive-disorders/lactose-intolerance-or-dairy-allergy#1. (accessed July 8th, 2020)
Center for Food Safety and Applied Nutrition. “What You Need to Know about Food Allergies.” U.S. Food and Drug Administration, FDA, 26 Sept. 2018, www.fda.gov/food/buy-store-serve-safe-food/what-you-need-know-about-food-allergies. (accessed July 8th, 2020)
Williams, Jennifer. “Does My Baby Have A Milk Allergy?” Abbott Nutrition News, Abbott , 4 June 2019, www.nutritionnews.abbott/pregnancy-childhood/infant-toddler/does-my-baby-have-a-cows-milk-allergy/. (accessed July 8th, 2020)
Thalheimer, Judith C. “Cow's Milk Allergy - Gaining an International Perspective.” Today's Dietitian, Great Valley Publishing Company, Feb. 2014, www.todaysdietitian.com/newarchives/020314p16.shtml. (accessed July 8th, 2020)
Sharma, S et al. “Structure and function of proteins involved in milk allergies.” Journal of chromatography. B, Biomedical sciences and applications vol. 756,1-2 (2001): 183-7. doi:10.1016/s0378-4347(01)00107-4 (accessed July 8th, 2020)
Żukiewicz-Sobczak, Wioletta Agnieszka, et al. “Causes, Symptoms and Prevention of Food Allergy.” Advances in Dermatology and Allergology, vol. 2, 12 Apr. 2013, pp. 113–116., doi:10.5114/pdia.2013.34162. (accessed July 8th, 2020)
Page updated
Google Sites
Report abuse