Final 10 - Enzymes

Reduces the activation energy for a biochemical reaction to occur • Very specific to the compounds they react with (eg: renin only works on k-casein, not a- or b-casein) • Has optimal condition to work - pH, temperature

No - enzymes are specialized proteins that speed up or start a chemical reaction without being changed by it (a catalyst - reduce activation energy needed to initiate reaction)

LOCK-KEY: substrates fit into a specific active site to form an enzyme-substrate complex INDUCED-FIT: when substrate gets close enough it induces the active site to change its structure to match the structure, so still a perfect match. After product is released the enzyme returns to its original structure

• water activity • concentration of solution • factors that denature protein • enzyme inhibitors

• Eg: yeast needs water to facilitate enzymatic activity • Reactions often need to happen in a solution • WA will affect how quickly enzymes move to work on a substrate

• When you have a low amount of a substrate compared to enzymes the reaction rate is slow • As more substrates are added reaction speed increases • UNTIL all active sites of enzymes are blocked, at which point reaction rate slows

HEAT • Most animal enzymes denature rapidly at temps >40C (104F) • Why vegetables are “blanched” before freezing PH • Each enzyme has optimal pH range • Enzyme denatures if pH is too high or too low • Eg- pepsin works best around pH 1.5-1.7; rennin pH <5.8 • Adjust pH to slow undesirable enzymatic activity IONIC STRENGTH/ELECTROLYTES • Work as coenzyme to promote enzymatic activity (Ca2+, Fe2+) • Stop important enzymatic activity (Hg2+, Pb2+) • Salt, such as NaCl, binds to enzymes of bacteria

• Any substance that will prevent the enzyme substrate complex from forming properly • Competitive • Uncompetitive - substance that can bind to non-active site of enzyme making so it doesn’t work • Noncompetitive • Naturally exist in many food products • Natural preservatives - block bacteria’s enzymatic activity • Eg- conalbumin in egg white, tomatin in tomato

• Make food texture more appealing (eg - meat tenderizer) • Preserve food (eg - changing into cheese) • Aid digestion (eg - lactase in milk

• Enzymatic browning in fruits and vegetables • Rotting action in foods • Fat rancidity

To clarify citrus juices or improve nutritional value

Raw pineapple contains an enzyme called Bromelain that is used to make meat tenderizer. • Rapidly breaks down the protein and muscle structure of the meat and turns it into a mush over time • Heating neutralizes the bromelain and will prevent it from giving your proteins a bad flavor

• Occurs when enzyme oxidases reacts with oxygen to produce brown pigments • Creates structural changes that causes produce to become mushy

• Store fruits in oxygen-free environment • Replace CO2 with nitrogen • Reduce injuries or bruises • Denature the enzyme by blanching • Store fruits in cold temperatures • Use preservatives - Sulfites - Ascorbic acid - Citric acid - Acetic acid

Vitamins and minerals

• Only come from plants; usually exist as pigment/color • Do not provide energy • Are not necessary for daily activities • Help fight disease (eg - heart disease, cancer)

onions, garlic, leeks, chives

legumes, soybeans, chickpeas, whole grains

blueberries, raspberries, grapes, peppers