PRINCIPLES OF FOOD SCIENCE
Skimmed Ch.1 (about various sciences involved in food science). Look in the Course
Manual, Unit 1 for a general summary.
2.1: FOOD COMPOSITION TABLES
Food Composition: refers to the substances or components found in a beverage or food.
Commodity: a useful consumer good, a product of agriculture, produced and delivered
for shipment; usually raw (red meats, poultry, fish/shellfish, eggs, dairy products,
beverage milks, fats/oils, fruitscanned/frozen/fresh/juices/dried, vegetablesall kinds,
shelled peanuts/tree nuts, flour/cereal products, calorie sweeteners, coffee, and cocoa).
5 Reasons to Consume Beverages:
thirst quenching stimulant effect alcoholic content health value
5 Examples of Beverages:
water caffeinated drinks beer/wine milk/fruit/veg juice
carbonated soft drinks
Nutrient Density: an item is considered to be dense if it supplies a variety of protein,
complex carbs, vitamins, and minerals without excess fat and calories.
Orange juice is much more nutrient dense than cola.
Degrees Brix: the sucrose concentration of beveragesthe weight % (per 100g) of sucrose
in solution. This can be determined using refractometry.
Sucrose Inversion: molecules split apart in sol’n to become fructose and glucose.
Fructose is the sweetest. Factors that increase inversion are low pH (high acidity) and
high temperature. It may be caused by the enzyme invertase or an acidulant.
Importance of °Brix/acid ratio: sucrose in solution contributes to flavour, but so does
the acid content. This ratio may vary across different orange juices.
2.3: CEREALS, GRAINS, AND BAKED PRODUCTS
Cereal Grains: corn, rice, wheat, barley, millet, rye, sorghum, and oats. These are high
in carbs (starch, glucose, maltose and fructose, and fiber). Cereals can be consumed
directly, milled into flours, or processed. Different cereals have different nutrient
Endosperm: main part of wheat kernel (83%)
Bran: layer of kernel (14.5%)
Germ: sprouting part of kernel (2.5%)
Biological value: the amount of nitrogen derived from food protein that is used in the
body to promote growth; related to the a.a. content of a protein. Cereal protein has lower
BV than animal protein (a.k.a. complete protein)
Bioavailability: degree to which nutrients are digested and absorbed in the body;
influenced by the food source (animal vs. plant) and food processing. Leavening: production of gases in dough that contributes to the volume achieved during
baking and the final aerated texture. Typical leavening agents include yeast, baking soda,
baking powder, and ammonium bicarbonate (produce CO2). Steam also contributes.
Breads, bagels, pastries, etc. are yeastraised where cakes, cookies, and doughnuts are
chemically leavened. Crackers, tortillas, etc. are unleavened.
2.4: FRUITS AND VEGETABLES
Fruit: fleshy or pulpy plant part commonly eaten as a dessert due to its sweetness. *In
botanical terms it is the ripened ovary of a plant (contains seeds)
Vegetable: plant or plant part that is served either raw or cooked as part of the main
course. *In botanical terms it contains an edible portion (leaf, root, stem, shoot, tuber,
flower). A vegetablefruit is the fruit part of a plant that is not sweet, and is served with
the main course (tomatoes, squash, cucumber). These can all be processed or fresh, and
have high water and low fat content. They are sources of sugar, starch, fiber, and various
vitamins. Getting enough of these will lower risk of heart disease and some cancers.
Ripeness: optimum flavour, colour, and texture.
Maturity: condition of fruit when picked (ex. can be mature but not yet ripe)
Harvesting: collection of fruits and vegetables and the specific time of peak quality in
terms of colour, texture, and flavour in order to market them.
Senescence: decline in quality of stored, respiring fruits and vegetable after harvest
viscosity colour (bruising, etc.) pH and titratable acidity (acid content)
Dehydration: removes moisture from fruits to prevent microbial/enzymatic
deterioration, and concentrates the nutrients. They can be sundried or dried in
dehydration chambers. Infusion can be used; heat and pressure force fructose into a fruit,
replacing water and adding flavour (colour, texture).
2.5: LEGUMES AND NUTS
Legumes: edible seeds and pods of certain flowering plants (beans, lentils, soybeans,
peas). They can be dried, canned, or fresh and are a good source of protein. They are low
in fat and sodium, and high in fiber, vitamins, and minerals.
Oilseeds: higher fat legumes (soybeans, cottonseed, sesame, sunflower, and peanut seed).
Whole soybeans can be fermented to produce miso, tempeh, and soy sauce. Pressed
soybeans produce oil and can be processed into flour.
Lipoxygenase: enzyme responsible for the “beany” or grassy taste of the first soymilk,
and can be deactivated by heat. Soybeans also produce a phytochemical called
Tree Nuts: nuts provide many nutrients, including phytochemicals and unsaturated fatty
acids, and are often roasted, in pastes or confections, and come from various ground
plants and trees (almonds, hazelnuts, pecans, macadamia, pistachios, walnuts). Peanuts
technically come from the pea and bean family.
Bitter almonds contain amygdalin that can be broken down to produce hydrogen cyanide
and is toxic. Sweet almonds such as Jordan almonds from Spain, and the softshell from
California are safe to eat and are often found in nougat or praline.
Hazelnuts are often combined with chocolate and are grown in S. Europe , Turkey, and Oregon. Pecans are native to America. Pistachios are pale green with a light tan shell
that is sometimes dyed red, and are grown in the Middle East and India, even under poor
crop conditions. Walnuts come in 2 types, regiafound in Iran, U.S., Europe, S. Africa,
etc. and black walnuts which are native to the U.S. These are used with cakes, chocolate,
and confection. Macadamia nuts have the hardest shell to crack, and are from Hawaii
and Australia from evergreen trees.
2.6: MEAT AND MEAT PRODUCTS
Meat: the edible flesh and organs of animals and fowls. Red meat describes the flesh of
cattle, pigs, and sheep. Poultry is considered white meat (chicken, turkey, duck). Meat
can either be a whole muscle with bone, whole muscle, or processed (ground, cured,
smoked, canned, frozen, patties). Meat byproducts include leftover organs and glands.
Meat contains highquality protein and many vitamins and minerals. Poultry consumption
has increased because of the lower fat and cholesterol content compared to red meat,
which has declined.
Myofibrils: several of these units form a muscle fiber. These units contain thin (actin)
and thick (myosin) filaments, which are responsible for muscle contraction by forming
cross linkages with each other to form a new protein called actinomyosin. Muscle fibres
are held together by connective tissue, composed of a watery dispersion of stromal
protein matrix plus adipose (fat) tissue. The 2 types are collagenwhite tissue that
determines toughness of meat in old and young animals, and elastin.
Comminuted Meat Emulsions: contain finely chopped meat mixed with water, fat, and
sometimes additives. Some meat proteins are considered soluble because they remain
dispersed within the watery phase, while others are insoluble and form gels. Frankfurters
and sausages are C.M.E.s where the O/W (oil in water) emulsion is entrapped in a gel
formed by the insoluble proteins and muscle fibres plus water.
Seafood contains all salt and freshwater animals and not just fish.
Finfish: with a backbone and fins (trout, cod)
Shellfish: include crustaceans, which are sea invertebrates with a hard upper shell and a
soft under shell (crab, shrimp, lobster) and mollusks, with 2 enclosing shells (clams,
oysters, scallops). Fish is generally high in protein, unsaturated fatty acids, and vitamins
A and D. Fish are also highly susceptible to rancidity and oxidation.
Why do fish rot so quickly?
It is because of the slime layer containing bacteria, which, once the fish dies, starts eating
away at the flesh. These bacteria are also psychrotrophic and can live in colder
temperatures. Fish struggle when caught, and use up muscle glycogen stores, so none can
be converted to lactic acid. Less acid means less preserved muscle tissue and therefore
more spoilage. Since fish are high in unsaturated fat, these molecules are unstable and
susceptible to oxidation. The phospholipids contain trimethylamine oxide (TMAO), which
is split by bacterial enzymes after the fish is captured. It becomes TMA, which is the
strong “fishy” odour. Omega3 fatty acids (linoleic a