FOOD 2010 Chapter Notes - Chapter 2: Lecithin, Myocyte, Hydrolysis

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CHAPTER 2
Food Groups and Categories:
o Beverages
o Cereals, grains, baked products
o Confectionary and chocolate
o Fruits and vegetables
o Legumes and nuts
o Meat, poultry, eggs seafood
o Milk
Food composition refers to the substances or components found in a beverage or food
- By identifying and quantifying the nutrients in foods, scientists have obtained the
data needed to develop tables of food composition.
Raw foods are composed of naturally occurring substances, while processed foods often
contain specific, functional additives.
Tables of food composition are printed by the U.S Department of Agriculture (USDA),
which provides nutritionists and consumers with information regarding the specific
nutrient and calorie (kcal) content of beverages and food.
Commodity is defined as “a useful consumer good, a product of agriculture, produced
and delivered for shipment”.
Processed commodities are value-added commodities derived from agricultural
commodities that offer convenience, longer shelf life and some added nutrients.
It’s not just what foods we eat but how much of it.
The quantity of food recommended by the Food Guide Pyramid is called servings;
product food labels specify serving sizes, tables of food composition employ measures.
The amount of food that counts as one serving depends on the food group.
Serving sizes are now more uniform and reflect the amounts people actually eat.
The Nutrition Labeling and Education Act (NLEA) define serving size as the amount of
food customarily eaten at one time.
Serving sizes that appear on food labels are based on the FDA-established lists of
“Reference Amounts of Customarily Consumed Per Eating Occasion” which must be
expressed in both common household and metric measures grams (g) and milliliters
(mL).
A beverage is a drinkable liquid, consumed for a variety of reasons, including thirst
quenching, stimulant effect, alcoholic content health value and enjoyment.
Nutrients are substances in foods and beverages that when absorbed into the body, are
used for specific functions like growth, maintenance and repair of tissues.
Nutrient density is a concept that applies to beverages and to foods if it supplies a
variety of protein, complex carbohydrates, vitamins and minerals without excess fat and
calories.
Commonly used beverage sweeteners are sugar (sucrose) and high-fructose corn syrup.
Sucrose is a part of the total soluble solids content of the beverage.
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The sucrose concentration of beverages is measured as degrees Brix (°Brix), which is
equal to the weight percent of sucrose in solution (grams of sucrose per 100 grams of
sample)
Any sweetened beverage formulation using sucrose as the only sweetener, the °Brix
reading is directly proportional to the amount of sucrose in solution.
The measurement of °Brix is made by refractometry, using either a refractometer of a
hydrometer device calibrated in degrees Brix, with corrections applied according to fruit
type and acid context.
Sucrose inversion; in which sucrose molecules in solution come apart and yield the two
component sugars, glucose and fructose. Fructose is a sweeter sugar than sucrose or
glucose, so sucrose inversion can affect the final sweetness and flavour of the beverage.
o Fructose due to inversion = sweetness increase.
Factors promoting sucrose inversion include:
o Low storage pH (high acidity)
o High storage temperature
o Desirable and created by the action of enzyme, invertase
o Action of acidulant
Food products analyzed for °Brix include:
o Syrups such as honey, maple syrup, and molasses
o Jams and jellies
o Tomato products
Flavour depends on the °Brix/acid ratio
o This ratio varies as the relative proportion of sugar to acid content, and is critical
in selecting certain fruit and vegetable types to make juices.
For fruits and vegetables the °Brix/acid ratio can vary according to region example
California oranges 8°Brix while Florida oranges 13°Brix
Different °Brix/acid ratios is one reason why consumers prefer one orange variety over
another.
Cereal grains, corn, rice, wheat, barley, millet, rye, sorghan and oats are among the
world’s major crops.
o Are high in carbohydrate content, such as starch, and the sugars glucose, maltose
and fructose as well as fibre.
Cereal grains can be consumed directly or milled into flours processed into a wide
variety of food products.
Two non-cereal crops, sugarcane and beets, are also processed into sugars and syrups.
Enriched cereal grain products are processed to contain added vitamins and minerals.
However, the layer of the kernel used also has an impact on nutrient composition ex.
Bran flakes contain significantly more protein and iron than corn flakes
Cereal grains are composed of 3 nutritious parts or structures
o Endosperm-which comprises about 83% of the kernel
o Bran layer which is about 15% of the kernel
o Germ-which is embryonic or sprouting part 2-2.5%
Energy and nutrient values vary among processed grain products
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Average unprocessed cereals are about 75% carbohydrate, 10% protein and up to 2% fat
The protein in cereal grains has a lower bioavailability and biological valve than protein
found in animals.
Biological valves refer to the amount of nitrogen derived from food protein that s used
in the body to promote growth.
BV is related to the amino acid content of a protein
A food high in BV is said to possess high-quality protein, meaning all the amino acids are
present.
Plant protein sources usually lack or are deficient in lysine and methionine and are
termed “incomplete proteins”
Bioavailability is the degree to which nutrients are digested and absorbed in the body.
Influenced by such factors as source (animal vs. plant) and food processing (certain
nutrients, such as the B vitamins, are destroyed by heating)
Leavening refers to the production of gases in dough that contributes to the volume
achieved during baking “leavening effect” and the final aerated texture
Typical leavening agents are: yeasts (ex of a biological leavening agent), baking soda
(NaHCO3, sodium bicarbonate), baking powder and ammonium bicarbonate (NH4HCO3)
Leavening agents function to produce carbon dioxide as the specific leavening gas.
Steam (heated water vapour) is also produced during baking and contributes to “oven
spring”
A fruit is a fleshy or pulpy plant part commonly eaten as a dessert due to its sweetness.
o In botanical terms, fruits are defines as the ripened ovary of a plant, which
means it contains seeds.
A vegetable is a plant or plant part or plant part that is served either raw
o Botanically a vegetable is an herbaceous plant containing on edible portion such
as a leaf, shoot, root, tuber, flower and stem.
A vegetable fruit is the fruit part of the plant that is not sweet, usually served with the
main course of a meal like cucumbers, squashes and tomatoes.
Fruits and vegetable shave many similarities in composition, methods of cultivation and
harvesting, storage properties and processing.
Most fresh fruit and vegetables are high in water content (up to 90%), low in protein (up
to 3.5%) and low in fat (up to 0.5%).
Fruits and vegetables contain various minerals, and are good sources of both digestible
carbohydrates (sugars and starches) and indigestible carbohydrates (fibre including
cellulose and peptic substances)
o Good sources of specific vitamins: the vitamin A precursor beta-carotene (in
green leafy vegetables and yellow-orange fruits and vegetables) and Vitamin C
(in citrus fruits, green leafy vegetables and tomatoes).
Research is discovering a link between a link between fruit and vegetable consumption
and health; foods high in vitamin A, beta-carotene, vitamin C and fibres, such as pectin
and these substances may provide a protective effect against heart disease and certain
cancers.
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