5th year- Home Ec

factors that affect food choice

culture, families, health status.

how can culture affect food choices

religious beliefs can affect food choices E.G Hindu’s not eating beef as they believe cows are sacred

how can families affect food choices

children observe what their families are eating so parents should provide healthy meals to set a good example

how can health status affect food choices

if a person wants to lose weight their food choices could differ e.g eating low fat or skimmed milk

what is a staple food

a food which is routinely eaten and makes up a large portion of a diet in a given population

what are nutrients

nutrients are chemical compounds that regulate body processes, provide heat and energy and assist growth and repair

types of nutrients

macronutrients and micronutrients

what are macronutrients

nutrients needed in large amounts E.G protein, lipids and carbohydrates

what are micronutrients

nutrients needed in small amounts E.G vitamins and minerals

what is recommended dietary allowance (RDA)

the estimated amount of a nutrient needed per day to maintain good health

What is reference intake (RI)

the guidelines about the appropriate amount of a particular nutrient required for a healthy diet

what are deficiency diseases

diseases that occur when the body is lacking in a particular nutrients E.G anaemia as a result of an iron deficiency

what is the elemental composition of a protein

carbon, hydrogen, oxygen, nitrogen and sometimes phosphorus, sulfur and iron

what is the chemical structure of proteins

proteins are large molecules (macronutrients) which are composed of amino acids which are joined together by peptide links to form a long chained polypeptide

what are essential amino acids

amino acids that cannot be manufactured by the body E.G Lycine, leucine and valine

what are non- essential amino acids

amino acids that can be manufactured by the body E.G asparagine, proline and serine

how are peptide links formed

peptide links are formed when two amino acids are joined together resulting in the loss of a water molecule (condensation reaction)

what happens in stage one of peptide link formation

the COOH (carboxyl) group of one amino acid reacts with the NH2 (amino) group of another amino acid

what happens in stage 2 of peptide link formation

the COOH group loses an OH group. the NH2 group loses a hydrogen atom. the OH and H join together to form a water molecule that is lost

what happens in stage 3 of peptide link formation

the result is a CO-NH bond which is a dipeptide

what is a dipeptide

when two amino acids join together

what is a polypeptide

when 20 or more amino acids join together

when is a protein formed

a protein is formed when 50 or more amino acids are joined together

what is the primary structure of a protein

the primary structure is the order or sequence of amino acids in protein chains

what is the secondary structure of protein

the secondary structure involves the folding of the primary structure of proteins into definite shapes

how do disulfide bonds occur

disulfide bonds occur when two sulfurs from two amino acids join together

how do hydrogen bonds occur

hydrogen bonds occur when a a H from the NH2 group of one amino acid and an O from the COOH group of another amino acid join together.

what amino acid can create a disulfide bond

cysteine

what amino acids can create a hydrogen bond

serine and tyrosine

what is the tertiary structure of a protein

the tertiary structure is the folding of the secondary structure into 3-D shapes

what are the the tertiary structures of a protein

fibrous and globular

what are fibrous polypeptide chains

fibrous polypeptide chains are arranged in straight, spiral or zig-zag shapes

what are the properties of a fibrous polypeptide chain and examples

fibrous polypeptide chains are insoluble in water, and hard to denature. E.G gluten (in wheat) and elastin and collagen (in meat connective tissue)

what are globular polypeptide chains

globular polypeptide chains are polypeptide chains arranged in a globular shape

what are the properties of a globular polypeptide chain and examples

globular polypeptide chains are soluble in water and easily denatured E.G ovalbumin (in egg whites) and lactalbumin (in milk)

what are the animal proteins

fibrous and globular

what are the plant proteins

glutenin’s and prolamine’s

examples of glutenin’s

glutenin and oryzenin

sources of glutenin and oryzenin

glutenin (wheat) and oryzenin (rice)

examples of prolamines

gliadin and zein

sources of gliadin and zein

gliadin (wheat) and zein (maize)

what is a conjugated protein

a protein that is formed when combined with a non protein molecule

what are the groups of conjugated proteins

phosphoproteins and lipoproteins

examples of phosphoproteins and source

caseinogen (milk)

examples of lipoproteins and source

lecithin (eggs)

what are animal sources of protein

meat, fish, eggs, milk, cheese

what are plant sources of protein

nuts, peas, lentils, cereals,beans

what are HBV proteins (high biological value)

HBV proteins are proteins that contain all essential amino acids mostly found in animal sources (except soya beans)

what are LBV proteins low (biological value)

LBV proteins are proteins that lack one or more of the essential amino acids mostly fund in plant sources (except gelatine)

what is denaturation

denaturation is change in nature of a protein chain. it involves the unfolding of a protein chain resulting in the irreversible change in shape

what cause denaturation

heat, chemicals, mechanical action, enzymes

how does heat cause denaturation

heat cause protein chains to unfold and bond together causing food to coagulate and set

what is the culinary application of heat in denaturation

egg whites turning from translucent to opaque at 60 degrees and the egg yolks coagulate at 68 degrees

how does mechanical action affect denaturation

beating and whipping can cause protein chains to unravel and partial coagulation to occur

culinary application of mechanical action

beating eggs to make meringue

how do enzymes cause denaturation in proteins

proteolytic enzymes such as papain in papaya tenderise meat

what is maillard reaction

the non- enzymic browning of food due to a reaction between certain amino acids and sugars under dry heat

what is gel formation

when collagen is heated and converted to gelatine

what is a culinary application in maillard reaction

roast potatoes, roast meat

what is a culinary application of gel formation

the setting of cheesecakes

what is the solubility of protein

most proteins are insoluble in water except collagen in meat (soluble in hot water) and egg albumin (soluble in cold water)

what is the culinary application of solubility

beef during stewing

what are the effects on dry and moist heat on proteins

• coagulation (egg whites coagulate at 60 degrees and yolks and 68 degrees

• colour change (myoglobin changes to haematin) red to brown

• overcooking causes proteins to become indigestible

effects of dry heat on proteins

maillard reaction e.g roast beef

effects of moist heat on proteins

collagen in meat converts to gelatine causing the fibres to tenderise e.g pulled pork

what is the