science of food test 1

Gelatin

• a structural protein found in bones, skin, and connective tissue

• processed collagen, giving gummies their classic chewy bounces

• missing essential amino acids

• has low biological value (BV)

• Not useful for muscle building or repair

Petroleum

• provides starting materials, which are chemically transformed and purified

Petroleum-derived

• describes the origin of raw materials, not the final product

• medications like ibuprofen and aspirin and food dyes are synthesized from these

Why Petroleum is not “bad” to eat

• a molecule doesn’t remember where it came from

• purity matters, not origin

Abundance in food supply in US

• more than 320,000 edible products for sale in the US

• large supermarkets carry about 50,000 of them

What consumers want in their foods today

• transparency

• sustainability

• health

• innovation

transparency

• ex: chipotle

• initiatives: provides detailed information about the sourcing ingredients, emphasizing non-GMO, locally sourced produce, and ethnically raised meats

sustainability

• ex: impossible foods

• initiatives: produces plant-based meat alternatives designed to reduce the environmental impact of food production - their products use significantly less water and land and emit fewer greenhouse gases compared to traditional meat

health

• ex: oatly

• initiatives: produces oat milk and other plant-based dairy alternatives that are marketed as healthier, most sustainable options compared to tradition dairy products - their products are non-GMO, free from artificial additives, and often fortified with essential nutrients

innovation

• ex: beyond meat

• initiatives: innovated the food industry by developing plant-based meat products that closely mimic the taste, texture, and appearance of traditional meant - they use a variety of plant proteins and advanced food science techniques

Iceberg lettuce

• a head of lettuce that is very low in nutritional value and flavor

• most abundant nutrient is water

Spinach

• high in vitamins A & C

• high in iron and folate

• good source of magnesium

Kale

• excellent source of vitamins A & C

• good source of calcium and potassium

locally grown produce

• conservation of fuel resources

• economic viability of local communities

• freshness

• better taste

Phytochemicals

• chemicals produced by plants

• favor brightly colored or strongly flavored vegetables and fruits, which are often the best sources of these

• in supplement form, may not be as easily absorbed as those from food

1/3 of all vegetables consumed in the US come from these 3 sources

• french fries

• potato chips

• iceberg lettuce

Milk

• a processed food - homogenized and pasteurized

• needs to be refrigerated right away; trucks unload in the back because fridges are there, stocking them as quick and easy as possible

• to a chemist, fat in this is just floating cream dispersed in skim milk

• the food industry processes food like raw milk to add value

Homogenization

• mechanical mixing in milk that breaks the fat into droplets so small that they stay in suspension

pasteurization

• heating milk to a high enough temperature to kill most disease-causing bacteria

Fermentation

• how yeast turns grapes into wine, milk to cheese & yogurt

Meat

• source of protein, fats, and a bundle of nutrients

• convenience, taste, price: main selling points

Gummies

• gelatin is added to the sugar syrup to give it a rubbery consistency

marshmallows

• contains gelatin, but air is whipped into the mixture to expand it into a foam - a mixture composed of gas bubbles dispersed in a liquid

Ice is about __% less dense than liquid water

9

Why does ice float?

• the heavier water displaces the lighter ice, so ice floats to the top

Why do we prefer chilled carbonated drinks?

• tap water is bacteriologically safe but chemically not pure enough for use in soft drinks

Cold water holds more ____________ than warm water

dissolved gases

Water

• its polarity helps dissolve substances like sugar and salt

• is called a universal solvent

• greatly affects the texture of foods

• crisp texture

• its form dictates the physical properties

• most active in liquid form —> necessary for microorganism to grow

• body does not store this

• regulates the body

• 1st nutrient to show signs of deficieny

• most essential nutrient

Water transports materials throughout the body

• most biological molecules (DNA, proteins, vitamins) are soluable in water

• sodium and potassium have to be able to circulate in the blood and the fluid between cells, all of which are mostly water

Water participates in metabolic reactions

• carbohydrates break down into sugars

• amino acids broken down from proteins

What happens when you don’t drink enough water?

• blood volume decrease

• this hormone signal the kidneys to reduce the amount of urine

What does the brain sense when you dont drink enough water?

• a decrease in blood volume

• increase in concentration of dissolved substance in the blood

• thirst signals arise; the mouth becomes dry

diet & water

• high protein diet increase water needs

• low calories diet increases water needs

• high-fiber diet increases water needs

Thirst

• means your cells are already dehydrated, a dry mouth is the last outward sign of dehydration

Additional facts about water

• baked foods do not have much water (they have the least amount)

• cooked white rice has more water than breads

• hydration myth: drink 8 cups of water a day

  • humans require 7-11 cups (56-58 oz) per day

Caramelization

• browning of sugars

• only requires heat and sugar

What causes bread to rise before and during baking?

• sugars are easily fermented by yeast cells; this produces carbon dioxide

The Maillard Reaction

• takes place when the crust of the bread is baked, having the highest exposure to heat

• requires heat, sugar, and amino acids (from protein)

• in bread, there are sugars, which react to amino acids in the presence of heat and create a brown color

What preserves fruit jams, jellies, & preserves?

• Sugar - it binds to water molecules, making them unavailable to microorganisms

Pectins & Gums

• both are soluble fibers with high affinity to water

• pectins are used in jams, jellies, and desserts

Names of gums seen on food labels

• fat replacers: low fat dressings, desserts

• starch replacers: baked goods, soups, sauces

• bulking agents: low fat foods

Sugar & Carbohydrates

• sugar is sweet, starch is a bland carbohydrate

• the only carbohydrates not changed to glucose are those that cannot be digested (ex: fiber)

• all carbs are made of simple sugars, linked together in several ways

Carbohydrate Info

• Energy 4 Kcal/gm

• primary role: provide the body with energy

• ultimate targets: brain and red blood cells

• made of carbon, hydrogen, and oxygen

________ are exclusive sources of carbohydrates

plant foods

_________ is the only animal-derived food that contains a significant amount of carbohyrdates

dairy milk

Monosaccharide #1

• is glucose

• blood sugar

• rarely occurs as a monosaccharide in foods, found as part of a disaccharide or starch

Monosaccharides #2 & #3

• are fructose and galactose

  • galactose is a part of disaccharide — lactose in milk

Disaccharides

• Sucrose

• Lactose

• Maltose

Sucrose

• glucose-fructose

• only sweetener called “sugar”

Lactose

• galactose-glucose

• only sugar found naturally in animal foods

• ____ intolerance: deficiency of enzyme lactase

Maltose

• glucose-glucose

Complex Carbohydrates #1

• are oligosaccharides

• 3-10 monosaccharides

• found in beans, legumes, onions, bananas, garlic, artichokes

Complex Carbohydrates #2

• are starch, fiber, & glycogen

• starch: storage form of carbohydrates in plants (potatoes, beets, rice)

• fiber: substances in plants; not digestible

• glycogen: storage form of carbohydrates in animals

What makes rice fluffy?

amylose

What makes rice sticky?

amylopectin

Sources of fats & oils

• may be animal, vegetable, or marine that may be processed and manufactured

• soybean oil is the highest volume vegetable oil used in the US

Instant puddings

• starch granules previously cooked & dried; they can reabsorb liquids again without heat

Visible fats

• those you can see and control, such as butter, oils, and the fat on meat

Invisible fats

• integrated into foods and not immediately noticeable, found in dairy products, baked goods, nuts, seeds, and many processed foods

Fats added to food

• add, modify, enhance flavor and texture

• aerate batters and doughs

• contribute flakiness

• contribute tenderness

• emulsify

• transfer hear, such as in frying

• provide satiety

• prevent sticking

Shorteners

• make baked goods tender and moist

• the way in which the fat is incorporated will affect the products’ overall texture

Do fats and oils go bad?

• deterioration of natural fats and oils

fats + oils =

lipids

Triglycerides

• comprise about 95% of lipids in food and the human body

• short-chain fatty acids (4-7 carbons)

• medium-chain fatty acids (8-12 carbons)

Fat structure

• saturated fats are nutrionally “bad”

• saturated fatty acids stack closely and are more solid

• unsaturated fatty acids are more fluid

• “hydrogenating” unsaturated fatty acids makes them more rigid

• maintain cell walls and play a role in making vitamin D

Saturated fat

• primarily animal sources: meat, milk, butter

• plant sources: chocolate, coconut, coconut oil

Monounsaturated fat

• sources: avocado, peanuts, peanut butter

Polyunsaturated fat

• primary plant sources: vegetable oils, margarine, mayonnaise

• animal sources: fish

Fatty acids

• those that must be consumed in the diet cannot be made by the body & not in sufficient quantities to meet the body’s needs

Phospholipids

• used extensively in food processing as emulsifiers

• egg yolk and soybean are the most important sources for these

Emulsifier

• a molecule with one oil-friendly and one water-friendly end

• without one, the water and oil content in food will look separate, which will give a very appealing appearance

Lecithin: an emulsifier

• a commercial source of this is soybean

• peanuts and most other nuts are good sources of this

Cholesterol

• helps make key hormones (estrogen, testosterone)

• synthesize vitamin D

• build and maintain cell membranes

• does not contain fatty acids

• a fat found only in animal products

How much fat do you need to eat?

• a person who eats 2000 calories daily needs no more than the equivalent of 6 teaspoons (2 tablespoons) of oil daily

• fish is a good source of omega-3 fatty acids

• go fish: at least 2 times (2 servings) a week

• chia seeds, walnuts, or supplements are also good sources of omega-3 fatty acids

Why hydrogenate oils?

• to increase shelf life

• obtain the cooking properties of solid shortenings, oils are partially hydrogenated

Hydrogenated fats

• hydrogenation reduces the number of double bonds

• converts liquid oils into solid fats: the melting point is raised, so it is easier to transport oils and spread on foods

Full hydrogenation

• process: where all the double bonds in a fat molecule are converted to single bonds — results in fat becoming fully saturated

• health impact: saturated fats can raise LDL (bad) cholesterol levels, but they do not contain trans fat

Partial hydrogenation

• process: where some of the double bonds are converted to single bonds — results in trans fatty acids

• health impact: trans fats are particularly harmful because they not only raise LDL (bad) cholesterol but also lower HDL (good) cholesterol, increasing the risk of heart disease

Where to find full hydrogenated fats?

• fully hydrogenated vegetable oils: margarines, certain types of peanut butter

• fully hydrogenated soybean oil: used in processed foods like baked goods and snack foods, utilized in commercial frying applications

Where to find partially hydrogenated fats?

• partially hydrogenated vegetable oils: margarines, cookies, cakes

• partially hydrogenated soybean oil: non-dairy creamers and frozen pizza

Fat substitues

• olestra

• lack of vitamins A, D, E, K

• digestive issues

Amino acids

• the building blocks of protein

• each protein has its own sequence of these

• these are joined together by peptide bonds

• the structure and sequence determine the functions of the protein

• made of carbon, hydrogen, oxygen, and nitrogen

• about 20 of them that are related to food

Gelatin basics

• dissolving in water

• formation of solid-like structure

• protein bonding

Properties of proteins in food

• can form into solids (cheese & tofu at room temperature)

• can form into gels (custard —> when eggs, milk, & sugar is heated)

Coagulation

• the process in which proteins in a food item form a solid mass

• ex: egg whites - when you cook egg whites, the proteins in them coagulate

• ex: cheese making - in cheese making, coagulation occurs when rennet, an enzyme, is added to milk (structure is built up from casein particle)

• with meat, this occurs when proteins solidify due to heat, ensuring thorough cooking and chaning texture

Coagulation of proteins gives stability & rigidity to foams

• proteins in milk, particularly casein, stabilize foam during frothing, providing texture and stretchability essential for creating intricate latte art designs

Denaturation

• the process by which the protein structure unfolds, altering its shape and function

• ex: cooking meat - the heat denatures the proteins

• ex: yogurt - denaturation occurs when bacteria ferment milk

• ex: whisking egg whites - proteins in the egg whites unfold and form new bonds with each other and with the air bubbles (mechanical ___)

• with meat, this alters the protein structure

Tender, juicy steak

• muscles are made up primarily of fiber made of 2 proteins called actin and myosin

• dry tough ____ — all proteins have been denatured

Dough stretching

• gluten is a protein found in wheat, barley, rye, and related grains

• it provides elasticity to the dough, helping it rise and maintain its shape during baking

Enzymes

• biological catalysts, usually proteins, are produced by living organisms/cells

• although they could be chemically synthesized in the laboratory, natural occurring ones are produced by biological systems

• important distinction: these are normally manufactured chemically

Proteins for meat tenderization

• muscle fibers are broken down using enzymes like papain and bromelain

• age the meat; natural proteases* break down the fibers

Essential amino acids - animal proteins

• generally provide all 9 essential amino acids in adequate proportions

• ex: eggs, milk, meat, fish (often called complete proteins)

Essential amino acids - plant proteins

• may be low in one or more essential amino acids

• limiting amino acids vary by food

  • ex: grains are low in lysine, legumes are low in methionine

• some plant foods provide all 9 essential amino acids in adequate amounts

  • ex: soy, quinoa, buckwheat

Dietary supplements

• they are not foods or drugs

• NOT consumed as a food replacement

• NOT marketed as a food replacement

• loosely regulated, “not evaluated by FDA”

Vitamins & minerals

• vitamins promote and regulate the body’s activities

• minerals contribute to the body’s structure and help regulate body processes

• the body’s need for vitamins and minerals are best met through the consumption of a wide variety of foods

the nature of vitamins

• organic (carbon) compounds are needed for normal function, growth, and maintenance

• they are not a source of calories

Calcium

• vitamin D aids absorption

• build in youth, lost in maturity

• osteoporosis - a pediatric disease with geriatric consequence

Potassium

• helps regulate blood pressure and supports normal heart function

• especially important for athletes because it is lost through sweat during prolonged or intense exercise

Salt

• raises the boiling point of water, such as during pasta cooking - it enhances flavor

• masks bitter and undesirable tastes

• binds water, helping control moisture and improve food stability

Minerals

• iron

• poor absorption from plant sources

• low iron causes anemia, especially in menstruating women