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8/12/2019 Food Chemistry Minor Nutrients
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CHE 462 Food Engineering 1
FOOD Chemistry
Minor Nutrients
Jan 16, 2012
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FOODSMajor Constituents
Water
3 major groups of constituents :
CARBOHYDRATES
PROTEINS
FATS
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FOODSMinor Constituents
Minerals
Vitamins
Enzymes Emulsifiers Acids
Antioxidants
Colours
Flavours
Sweeteners
Gums (hydrocolloids)
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PIGMENTS AND COLOURS (contd)
Food colour may be controlled :
Sugars caramelize and change colour when heated.
Examples of caramelization: Darkening of maple syrup,
Colour on toasted bread,
Brown colour on caramel candy
Maillard reaction or Browning reaction occurs when
dark colours result from interactions between proteins(amino acid group) and Reducing Sugars
e.g. darkening of dried milk on long storage.
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FLAVOURS & AROMA
Very complex subject in foodprocessing e.g. In Coffee
Over 800 constituents identified forflavour and aroma.
Organics sensitive to air, heat are
interacting with one another.Best coffee within first 15 mins.
Cured meat Flavour (U of T Research)
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Prevention of oxidation in
cured meat U of T Research
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Food Safety aspect Clostridium Botulinum under anaerobic conditions & pH > 4.6
can produce lethal toxin. C. Botulinum does not grow in foodwith organic acids and a pH
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OXIDANTS & ANTI-OXIDANTS
Many food constituents are adversely affected by oxygenin airfats & oils become rancid, carotenes which yieldsvitamin A & ascorbic acid (vitamin C) diminish in their
vitamin activity; Cu, Fe & some metals are strong catalysts of oxidation
stainless steel processing equipment are preferred;
Natural anti-oxidants present in food include
Lecithinalso an emulsifier, Vitamins C & E,
Certain sulphur containing amino acids;
Most effective anti-oxidants are synthetic approved bythe Food & Drug Admin. (FDA).
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Sweeteners
Aspartame
Sucralose
Ace-K
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Hydrocolloid
Pectin
Guar gum
Carob bean gum
Carrageenan
Xanthan gum
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NUTRITIVE ASPECT OF FOODS
Foods areFuel for chemical energy to the body.
Major sources of Energy
Carbohydrates,Fats,Proteins Energy value of Foods [=] Calories
Total Potential Energy (TPE) determined by bomb
calorimetry
Calorific Energy (CE) derivable by animals or humans
Usually CE < TPE
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calories and kilocalories
The scientific definition of a kilocalorie is the amount ofenergy needed to raise the temperature of 1 kilogram ofwater one degree Celsius from 15to 16.
The true calorie, sometimes referred to as a "smallcalorie," is the amount of energy needed to raise thetemperature of one gram of water one degree Celsiusfrom 15to 16.
A kilocalorie is equal to 1000 calories. While the term"calorie" technically applies to the "small calorie," in
common usage, such as in reference to food energy, theterm "calorie" is actually a kilocalorie.
Internationally, most countries express food energy inkilojoules (kJ). One kcal equals 4.184 kJ. The USDANational Nutrient Database for Standard Referencecontains values for both kilocalories and kilojoules.
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Energy from a light Lunch
What is the calorie content of your light lunch whichconsists of salad and a custard filled pastry?
Salad: 250g : 2% Carb + 0% fat + 1% Protein
Pastry: 200g: 30% Carb + 20% fat + 10% protein
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Energy from a light Lunch
Solution: Use the 4-9-4 method for calorie contents
C F P Total Cal
Salad wt. (g) 5 0 2.5
Energy (Cal) 20 0 10 30
Pastry wt. (g) 60 40 20Energy (Cal) 240 360 80 680
(CE) for light lunch = 680 + 30 = 710 Cal
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METABOLISM (contd)
Calories for Body Energy Requirements (BER):Production of Body Heat
Synthesis of Body Tissue
Performance of Work.
Case 1:
Body performs little work---Most of BER stored as FAT
Case 2:
Body Energy demands is high. Body fat & tissues are
oxidized to supply energy. (body loses weight).
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METABOLISM (contd)
Daily Energy Requirement:
Avg. Daily Demand for Adult: 2000 - 2500 - 3000 to 5000Cal/day
When Daily Intake is < 2000 Cal/day, there is DietaryInsufficiency which results in Malnutrition with chronicInsufficiency.
Examp le of Weigh t Gain:An excess intake of 9 g of butter or margarine daily canresult in the gaining of 3.2 kg of fat (wt.) in a year!!! Butfortunately this can be counteracted by walking 2.4 kmdaily.
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Other Roles of C, P and F in Nutrition
C, P, Fareinterrelated and interconvertible in metabolism. Human Bodywithout Ccan survive with P & F to fulfill its body
energy requirements and to synthesize blood glucose, liver glycogen,
ribose sugar components of nucleic acids and other importantcarbohydrates.
BUT consumption of Carb assist in using Fat efficiently.
Inefficient oxidation of Fat leads to accumulation of ketone bodies, adisease known as ketosis.
Without Carb, Protein is used up for energy at the expense of bodyrequirements for protein & amino acids.
Celluloses and Hemicelluloses provide fibre and bulk essential tohealthy intestine.
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Other Roles of C, P and F in Nutrition
Carb such as Starch and Lactoseare slow to dissolve, and stay in the
intestine longer than soluble Carbsugars
they serve as nutrients for
microorganisms that synthesize several
Vitamins of the B-complex
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Other Roles of C, P & F in Nutrition
Fats beside supplying energy provide
polyunsaturated fatty acids (PUFA), e.g.
Linoleic Acidan essential FA;
Most animals need linoleic acid but cannot
synthesize it : must be supplied as diet;
Lack of linoleic acid interferes with growth of
human infants, and also causes skin disorder; Good sources of linoleic acidgrain and
seed oil, fats from nuts & poultry;
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Other Roles of C, P & F in Nutrition
Linoleic Acid & other PUFA can lower bloodcholesterol levels.
Fat insulates the body against rapid changes
in temperature;
Fat helps cushion body organs from sudden
injury;
Excess Fat is stored in the adipose (fatty)tissue an used as a reserve source of energy
In excessive amount - OBESITY.
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Nutritional Value of Proteins
Depends on their different Amino acidcomposition.
A Complete Protein (CP) - one with all the
amino acids in the amounts and proportions
to maintain life and support growth when
used as sole source of protein.
Incomplete Protein can be supplemented withthe missing essential amino acids as
synthetic compounds.
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Nutritional Value of Proteins(contd)
A CP has High Biological Value (HBV) e.g. meat, poultry, fish, milk, eggs
An exceptionGELATINcontain small amountsof isoleucine, threonine and methionine; but NOtryptophan
Animal HBV >> Plant HBV
e.g. wheat, rice and corn lack Lysine butcorn also lacks tryptophan.
Legumes have high protein quality but have lowlevel of Methionine.
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Nutritional Value of Proteins (contd)
Daily Requirements:
40 to 60 g (after early childhood)
Depends on body demandgreatestduring growth; pregnancy; lactation.
Protein Malnutrition can cause
irreversible damage such as mentalretardation.
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PROTEIN QUALITY
1. Growth
2. Replacement of metabolic losses or damaged tissue
3. Reproduction
4. Lactation and
5. General well-being
Accuracy & Reliability of Amino acids analysis
Availability & Digestabilitiy
Palatability of the protein foods
PROTEINS ( td)
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PROTEINS (contd)
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BIOAVAILABILITY OF NUTRIENTS
A nutrient is bioavailable if it is utilizable inmetabolism.
Inf luenc ing factor s for bioavai labi l i ty: Food Digestability
Nutrients absorbability from the intestinal tract.
Processing and cooking
Age, Gender, physiological health, consumption ofdrugs, general nutritional status, combinations of foods
eaten together, etc.
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VITAMINS
Organic chemicals (not essential amino acids& fatty acids).
Must be supplied to animals in small amountsto maintain health.
Vitamin D is the only major vitamin
synthesized by the human body.
Vitamins function in enzyme systems thatfacilitates metabolism of C, P & F.
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VITAMINS (contd)
FAT SOLUBLEVitamin A
Vitamin D
Vitamins E & K
WATER SOLUBLEVitamin C
Vitamins - B complex
VITAMINS
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VITAMIN ACTIVITY
1. Biological Activity, based on Vitamin A, (BA) ismeasured in IU (International Unit)
2. In case of Vitamin A (Retinol), Carotene andother caroteniods, BA is measured in
RE = Retinol Equivalent where
1 RE = 1 g Retinol = 6 g Carotene
3.33 IU of vitamin activity from Retinol
10 IU of vitamin activity from Carotene
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VITAMIN A
Food Sources: (1) Animalsmeat, liver milk, fish oils,dairy products, egg.
(2) Plants - Carotene (Vit. A precursor) in orange, yellow& green veges, e.g. carrots, squash sweet potatos, kale,spinach, etc.(3) Synthetically made.
Deficiency: (1) Blindness; (2) Failure of normal bone &
tooth development in the young; (3) Diseases ofepithelial cells (lining under skin) and membranes of thenose, throat & eyes, decrease in bodys resistance toinfection.
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VITAMIN D
Food Sou rces:- Most foods are LOW in Vit. D;Liver, fish oils, dairy products, eggs.
Other sources:- Formed in human and animal
skin by activation of sterols (cholesterolunder
animal skin or ergesterolin yeast) by UV light
from the sun or artificially.
Defic iency:- Bone defectsprincipally rickets,brittle bones and scaly skin.
VITAMIN E
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VITAMIN E
(a.k.a. -tocopherol)
An anti-sterility factor in rats.
Essential for normal muscle tone in dogsand other animals
Its significance for humans is stilluncertain.
Funct ions: (1) Strong anti-oxidant inhuman metabolism; (2) Facilitatesabsorption of Fe; maintance of biologicalmembranes.
Sources: Vegetable oils.
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VITAMIN E (contd)
Deficiency: * Rare under practicalconditions of human nutrition
* In large doseshas been promotedas (1) a remedy for numerous diseases
an (2) an agent for prolonging youth and
increase sexual potency (no scientificevidence!!).
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VITAMIN C(a.k.a. Ascorbic Acid)
It is theAnti-Scurvyvitamin.
Funct ions:- (1) Necessary for normal formation
of protein collagen, which is an importantconstituent of skin and connective tissue; (2)
Facilitates absorption of Fe.
Sources:- Citrus fruits, tomatoes, cabbage,
green peppers, potatoes; (milk.cereals andmeats are poor sources of Vit. C).
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VITAMINS f th B C l G
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VITAMINS- of the B Complex Group
B1- (Thiamin)
B2(Riboflavin)
Niacin (Nicotinic Acid)
B6
Panthothenic Acid (B5)
B12
Folacin
Biotin & Choline
All generally found inLiver, Yeast, Bran ofCereal grains, egg yolk,
broccoli, lean beef, skimmilk, sweet potatoes,molasses .
Required for essentialmetabolic activities.
Deficiencies = specificdiseases.
Mi l
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Minerals
Calcium: needed for healthy bones and teeth, normalblood clotting, and nervous system functioningsources: dairy products, broccoli, cabbage, kale, tofu,
sardines and salmonIron: needed for the formation of hemoglobin, which
carries oxygen from the lungs to the body cellssources: meats, eggs, dark green leafy vegetables,legumes, whole grains and enriched food products
Phosphorus: needed for healthy bones and teeth,energy metabolism, and acid base balance in thebodysources: milk, grains, lean meats, food additives
Minerals
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Minerals
Magnesium: needed for healthy bones and teeth,proper nervous system functioning, and energymetabolismsources: dairy products, meat, fish, poultry, green
vegetables, legumesZinc: needed for cell reproduction, tissue growth and
repairsources: meat, seafood, and liver, eggs, milk, whole-grain products
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Additional Reference
Check the following site of U.S. Drug Admin. -http://www.nal.usda.gov/fnic/etext/000105.html- on vitamins, minerals and nutrients for:
Sources
Recommended Daily Intake (RDI)
Deficiency Symptoms
http://www.nal.usda.gov/fnic/etext/000105.htmlhttp://www.nal.usda.gov/fnic/etext/000105.html