food chemistry minor nutrients

8/12/2019 Food Chemistry Minor Nutrients

1/44

CHE 462 Food Engineering 1

FOOD Chemistry

Minor Nutrients

Jan 16, 2012


2/44


FOODSMajor Constituents

Water

3 major groups of constituents :

CARBOHYDRATES

PROTEINS

FATS


3/44


FOODSMinor Constituents

Minerals

Vitamins

Enzymes Emulsifiers Acids

Antioxidants

Colours

Flavours

Sweeteners

Gums (hydrocolloids)


4/44


5/44


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.


6/44


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)


7/44CHE 462 Food Engineering 7

Prevention of oxidation in

cured meat U of T Research


8/44



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



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).


11/44



Sweeteners

Aspartame

Sucralose

Ace-K


13/44


Hydrocolloid

Pectin

Guar gum

Carob bean gum

Carrageenan

Xanthan gum


14/44


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


15/44


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.


16/44


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


17/44


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


18/44


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).


19/44


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.


20/44


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.


21/44


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


22/44


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;


23/44


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.


24/44


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.


25/44


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.


26/44


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.


27/44


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)


28/44


PROTEINS (contd)


29/44


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.


30/44


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.


31/44


VITAMINS (contd)

FAT SOLUBLEVitamin A

Vitamin D

Vitamins E & K

WATER SOLUBLEVitamin C

Vitamins - B complex

VITAMINS


32/44


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


33/44


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.


34/44


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


35/44


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.


36/44


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!!).


37/44


38/44


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).


39/44

VITAMINS f th B C l G


40/44


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


41/44


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


42/44


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


43/44


44/44

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

food chemistry minor nutrients

Documents