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PROTEINS The Science of Food. What are Proteins? Amino Acids Amino Acids Essential amino acids Complimentary proteins Specific chemical properties (charge,

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Presentation on theme: "PROTEINS The Science of Food. What are Proteins? Amino Acids Amino Acids Essential amino acids Complimentary proteins Specific chemical properties (charge,"— Presentation transcript:

1 PROTEINS The Science of Food

2 What are Proteins? Amino Acids Amino Acids Essential amino acids Complimentary proteins Specific chemical properties (charge, hydrophic, hydrophilic) Amino acid chemistries give proteins their primary, secondary, tertiary structure Structure function relationships Biological roles of proteins

3 Organization of Information- From Genetics to Protein 1. Proteins are made of amino acids. 2. The amino acids are chemically different and can occur in any order. (ate, eat, tea) 3. The amino acids chemically interact with each other to give the protein its shape and function.

4 Essential Amino acids There are eight amino acids that cannot be produced by the human body Histidine, Isoleucine, Leucine, Lysine, Phenyl-alanine, lysine, methionine, threonine, Valine Complete proteins contain all the essential amino acids Incomplete proteins lack one or more Complimentary proteins make up for each other’s deficiency Beans lack methionine, Corn lacks lysine Other complimentary proteins: Soybean & sesame, Rice and black-eyed peas There are eight amino acids that cannot be produced by the human body. Histidine, Isoleucine, Leucine, Lysine, Phenyl-alanine, lysine, methionine, threonine, Valine Complete proteins contain all the essential amino acids. Incomplete proteins lack one or more Complimentary proteins make up for each other’s deficiency. Beans lack methionine. Corn lacks lysine. Other complimentary proteins: Soybean & sesame, Rice and black-eyed peas

5 Peptide bonds and Primary Structure

6 Protein measurement- measure # of amino ends. Protein adulteration- add melamine, many amino ends.

7 Secondary structure Alpha helix Beta Pleated Sheet

8 Tertiary structure The overall conformation that arises from the secondary structure

9 Show chain demonstration Do protein denaturation demonstration Start attendance sheets

10 Conventional Wisdom, The “Central Dogma of Biology” DNA makes RNA makes (only one) Protein. Corollary: Only DNA can transmit information. (Proteins store that information.)

11 Stanley B. Pusiner

12 Puisner discovers prions! Human TSEs include Creuzfeldt-Jacob disease (CJD), Familial fatal insomnia (FFI), Kuru, and Gerstmann-Straussler-Scheinker disease (GSS). Animal TSEs (aka “Mad Cow”)

13 Stanley B. Pusiner, 1997 Nobel Prize

14 Biological Functions of Proteins Catalysis - enzymes Movement –actin, myosin, trypomysin Antigens Antibodies Toxins Structure –collagen, Keratin Transfer – Iron, O 2

15 Actin and Myosin The muscles in your body are made of the proteins actin and myosin. The use a combination of Ca 2+ and ATP to contract and release. The muscles in a body will under go rigor mortis once there is no energy going through them. (Tenderization)

16 Functions of Proteins in Foods Precipitation – loss of solubility (milk, casein, para-kapppa casein – denaturation) Flocculation –aggregation without denaturation, clarification Coagulation – internal self association Gelatinization- ordered self association

17 Functions of Proteins in Foods Emulisfication Dough formation Color and flavor formation Water binding, foaming, viscosity

18 Proteins and Nutrition 4 Cal/gram Protein Quality = Protein Efficiency Ratio FoodP.E.R Eggs3.5 Milk2.7 Beef2.6 TVP1.7 Peanut Butter1.5 White Bread0.8 Corn Chips0.5 P.E.R = weight gain in rat per gram of protein Meat: 10-20 pounds feed  1 pound beef Poultry: 1.5 pound feed  1 pound poultry Meat has 15-20% protein, 5-40% fat, rest water

19 Meat: 10-20 pounds feed  1 pound beef Poultry: 1.5 pound feed  1 pound poultry Meat has 15-20% protein, 5-40% fat, remainder is water

20 Protein Requirements PersonRequirement Adult male56g Adult female46g Lactating female70g Average American 90g Athletes need more. 4:1 carb:protein

21 Enzymes Make reactions go faster Have no side products Are highly specific Natural – no one has ever chemically synthesized an enzyme Work at relatively low temperatures “Gentle”

22 Enzymes in Foods EnzymeAction“Naturally”In food processing Amylase glucoamylase Breaks down starch to glucose Saliva, barley malt, “softening” Makes fermentable sugars for bakers and brewers, Aids moisture retention, Clarification of liquids InvertaseBreaks down sucrose to glucose and fructose YeastChocolate covered cherries PectinaseBreaks down pectin to glucoromic acid Fruit softeningClarification, improved pressing yields, separation of mandarin orange segments Glucose Isomerase Turns glucose in fructose MicrobialHigh-fructose corn syrup ProteasesBreaks up proteins into amino acids “proteolytic spoilage” of meat and fish Meat tenderization, chill-proofing of beer, Production of protein hydrolysates, texture, dough rheology papinPineapple

23 Enzymatic Reactions in Foods Lipases break down triglycerides to mono and diglycerides Polyphenol oxidase causes the natural browning of foods

24 Summary of Proteins The information in genes is translated into a specific sequence of amino acids. The information in the amino acid sequence determines the protein’s secondary, tertiary, sequence and ultimately functions. Diverse functions of proteins nutrition movement functions in food enzymes


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