Different measures
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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.
Different measures
- 1. DIFFERENT MEASUREMENTS USED IN FOOD SCIENCE Presentation by NAG-A 32 111718012032
- 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.
- 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
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