This document discusses different measurements used in food science. It defines key terms like density, phase changes, pH, osmosis, reverse osmosis, surface tension, specific gravity, and emulsification. It also discusses water balance in the body, water intake and loss, the role of water in the body, and water requirements. Water balance is regulated by thirst and the brain and kidneys. Too little water leads to dehydration while too much can cause water intoxication. Solutions are mixtures formed by dissolving one or more solutes in a solvent.

1. DIFFERENT MEASUREMENTS
USED IN FOOD SCIENCE
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NAG-A 32
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2. DIFFERENT MEASUREMENTS
USED IN FOOD SCIENCE
Food may be existed in any form such as powder, solid,
granular, liquid phase etc.
The strongest of the bonds that are important in food
chemicals is the covalent bond.

3. DEFINITIONS
• Density: It is mass(m) per unit volume(V). It is
represented by “ρ ”.
Units: kg/m3. Instrument: Hydrometer.
• Phase changes: It refer to a change in matter form one
state to another.
Most familiar phase changes are:,
Freezing water to ice, boiling liquid water to create gas
etc.
The heat plays a major role in changing matter from
one phase to another.

4. Phase change cycle

5. • PH: It is defined as the negative logarithmic of H+ ion
concentration.
• H is expressed as reaction of field i.e. between acid and
base. It scale range from 0-14.
• Acids : The scale range from 0 to 7.
• Base: The scale range from 7 to 14.
• Neutral : 7 ex: water.
• Most yeasts favor a pH around 4 - 4.5.
• Most can tolerate pH much below 4.
• Most bacteria favor a pH around 7.

7. Classification of foods on the basis of
pH:
• Low acid foods: If pH is 5 or above 5.
Ex: Peas, maize, corn, cauliflower, potato, Spanish,
beans, etc.
• Medium acid foods: If pH is 4.5 -5.
Ex : Meat & vegetable mixture, soups, sauces, fish,
carrot, okra, cabbage etc.
• Acid foods: If pH is below 3.7 or 3.7.
Ex: Tomatoes, pears, pineapple, banana, mango etc.

8. • Highly acidic foods: If pH is 3.7.
Ex: Pickles, citrus, juices, rhubarb, prune, chutney
etc.
• Lowering the pH of a food system reduces the rate
of browning of foods.
• After an animal is killed, anaerobic glycol sis
causes a drop in muscle pH . This drop is caused
by the buildup of lactic acid in the muscle tissue.

10. • Osmosis: If two solutions of different conc. Are separated
by a semi-permeable membrane which is permeable to the
smaller solvent molecules but not to the larger solute
molecules, then time solvent will tend to diffuse across the
membrane from the less concentrated to the more conc.
Solution. This process is called osmosis.
Ex: Osmosis are when plant roots absorb water from the
soil& our kidneys absorb water from our blood.

11. • Reverse Osmosis: It is the process of osmosis in reverse.
Ex: When pressure is applied to the concentrated solution, the
water molecules are forced trough the semi- permeable and
contaminates are not allowed through.
• Surface tension: It is defined as dragging force observed in
the given liquid per unit length.
T=F/L F: Force per unit length.
L: Length over which the force acts.
Units: N/m .

12. • Specific gravity: lt is the ratio of the density of a
substance to the density of reference material.
Ex: Specific gravity of solution is
Density of solution
Density of water
• An object with a specific gravity less than 1 will
float in water.
• Colloidal Systems: Colloidal Systems or
Colloidal dispersions are intermediate between
true solution and suspensions.

13. Types of colloidal system
• A colloidal system is made of two phases.
• Dispersed phase: A substance distributed as the
colloidal particles.
• Dispersed medium: The second continues phase in
which the colloidal particles are dispersed.
Ex: A colloidal solution of copper in water, copper
particles constitute the dispersed phase & water the
dispersed medium.

15. Dispersed phase Continuous phase
dispersed medium
Dispersed type
colloidal system Examples
Gas Liquid Foam Whipped cream
Gas Solid Solid foam Cork
Liquid Gas Aerosol Clouds, fog
Liquid Liquid Emulsion Milk
Liquid Solid Solid emulsion Butter, cheese
Solid Gas Smoke, powder Dust
Solid Liquid Suspension, sol Paint, Ink
Solid Solid Solid sol Ruby glass Alloy

16. • Sols: Sols are colloidal system in which a solid dispersed
in a liquid. These are sub divided in two classes.
A) Lyophilic Sols
B) Lyophobic Sols
• Lyophilic sols: These are those in which the dispersed
phase exhibits a definite affinity of the medium or the
solvent.
Ex: Dispersions of starch gum & protein in water.
• Lyophobic sols: these are those in which the dispersed
phase no attraction for the medium or the solvent.
• Ex: Sulphur in water

17. • Emulsification: Creation of an emulsion by the dispersion
of one immiscible liquid in the form of small droplets in a
second immiscible liquid. These are two types of food
emulsions, oil in water(o/w) & water in oil(w/o).

18. • Water: Its is a colorless, odorless and tasteless
liquid.
• Water can exist in three states those are,
Solid,
Liquid and
Gas.

19. Distribution of water in the body

20. Water intake and loss

21. Water intake and source of body water:
• Water is taken as drinking water: about 1500 ml.
• Through food: 1000ml
• Oxidation of carbohydrates fats and proteins in
tissues: 300 ml.
Water loss: the body loss water through,
• Urine: 1500 ml
• Via skin: 800 ml
• Lungs: 400 ml
• Fasces: 100 ml

22. • Water Balance: Water balance refer to the
balance between the amount of water consumed
and the amount of water excreted.
• Water Intake Regulation: When there is
excessive loss of water from the body, the
concentration of solutes in the blood becomes too
high solutes attract water from the salivary
glands, making the mouth dry and causing a
person to feel thirsty.

23. • Water excretion Regulation: The brain and kidneys
regulate the amount of water excreted by the body.
When the blood volume us low, the concentration of
solutes in the blood is high. The brain responds to
this situation by simulating the pituitary gland to
release a hormone known as Anti diuretic
hormone(ADH), which signals the kidneys to
reabsorb and re-circulate water. When the individual
needs more water, the kidneys will excrete less and
even reabsorb some.

24. • The kidneys respond by secreting an enzyme
called rennin.
• Rennin Angiotensiongen Angiotensin
• Angiotensin Adrenal gland Aldosterone (hormone)
• Functions:
• In the human body water performs the functions:
• Regulates body temperatures
• Carries nutrients though out the body
• Improves digestion
• Eliminates waste and toxins from the body.

25. • Requirements:
• Recommended amount of water (liters/day).
• Children – 1.3 to 1.7
• Men – 3.7
• Women - 2.7
• pregnant – 3.0
• Lactating Women – 3.8
• Water Imbalance: Too much water- whatever
amount the kidneys are unable to excrete.

26. • Water Intoxication: Water Intoxication occurs
when there is too much fluid in the body.
• Dehydration: Dehydration of the body results
when water is not taken in adequate amounts to
make up the water loss.

27. • Solutions: A solution is a mixture formed when one
or more solutes dissolved in a solvent

28. THANK YOU