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Food Sciences




  • What is Food?
     

    Any substance that, when ingested, will supply nutrients such as carbohydrates, Proteins, Mineral Vitamins, H2O that nourish the body.

    What is Food?

    Any substance that, when ingested, will supply nutrients such as carbohydrates, Proteins, Mineral Vitamins, H2O that nourish the body.
    Define Nutrition?
    Nutrition´s a science that deals with the fate or path of the food in the body.
    What is Canning Technology? Principle of Canning is sterilization by heat.Four important steps in this method.

    • Placing the food to be preserved in bottles.
    • Closing the bottles with utmost care.
    • Subjecting bottles to the action of boiling H2O for the certain length of time.
    • Removing the bottles from the H2O bath at the end of the prescribed period.
    What is Canning? The preserving method in which food is preserved in hermetically sealed container.
    Which Chemical is responsible for Heat production in Chilies? Capsicin
    What is the most common method of food preservation in Pakistan? Cold Storage and Sun-drying.
    What is Synersis? .The Separation of Liquid phase from the solid phase (mostly in Jam Jellies, Marmalades) is known as synersis.
    What is Blanching? .Blanching is the heating of some plant food material in hot water or steam for a very short time mainly to destroy active food enzymes.
    Why we expel. extra cellular spaces by blanching? .To reduce the volume of material.
    What is the function of Blanching? .Following are the function of Blanching:

    • It loosens the skin
    • It cleans the product by removing adhering contaminants.
    • It removes tissue gas from leafy vegetable.
    • It helps to fix the green color.
    Differentiate b/w aseptic canning and conventional canning?
    Aseptic Canning: Food is first heat processed and then filled or packed aseptically into suitable sterile containers. Commercial Thermal Processing/Conventional Canning: Food is filled into the container which is sealed hermetically and then subjected to high temperature.
    Differentiate b/w Cold Storage & freezer Storage?
    Cold Storage: refers to the storage condition where food is held at a temperature around its freezing point.
    Freezer Storage: Describes the Situation where food is held in frozen state at a temperature below freezing point.
    What is the difference b/w spoilage &-deterioration?
    Spoilage: The spoilage of foods as a result of microbial enzymatic activity.
    Deterioration: Deterioration in foods caused by physical phenomena that occur during processing handling &-storage.

    Differentiate b/w baking & barbecuting?

    Baking: Cooking in an oven with dry heat (100-232oC). Barbecuting: Direct heating over glowing, smokeless wood fire.

    Differentiate b/w roasting &-broasting?
    Roasting: Cooking by dry heat in oven or closed vessel with just a little fat. Broasting: Pressure frying
    What is the Difference b/w Pasteurization & Sterilization?
    Pasteurization: Pasteurization treatment (65oC-88oC) is applied to kill pathogenic organisms including bacteria &-yeast (Vegetative form of bacteria are killed).
    Sterilization: Sterilization employs much higher temperature (100oC or above) to destroy all microbial forms (Vegetative + Spores).
    Define Tyndallization?
    Tyndallization is the process by which vegetative forms of microorganisms are Killed at 80oC-100oC the germination of resistant spores(37oC)germinated spores are subsequently Killed by reheating at the same temperature.
    What foods called commercially sterile foods?
    For a food stuff to be declared commercially sterile all pathogenic &-target spoilage vegetative microorganisms present in food must be destroyed Additionally, microbial spores that may thrive under the subsequent handling &-storage conditions must also be eliminated.
    In which areas the primary taste is detected?
    Following are the areas :
    • Sour Taste: Is most readily detected on the sides of the tongue.
    • Salty Taste: On the Sides &-tips
    • Sweet Taste: On the tip.
    • Bitter Taste: On the back of the tongue on the pharynx.
    Name some Oxidizing/bleaching agents used in flour ?.Benzoyl peroxide, nitrogen dioxide.
    What is meant by bound water ?.The water which is physically or chemically bounded which can be or can not be removed, it is unavailable as solvent & it is also non-freezable.
    What is meant by Crude fiber ?The fiber which can not be digested by human digestive system.
    What is the significance of digestible carbohydrate in human diet ?.These provide readily available energy to the human body.
    What is the significance of total solid in foods ?.Amount of total solids determines the quality & nutritional value of a food.
    Why are total solids important in dehydration of foods ?In dehydration we decrease available water so as to increase total solids for better quality & storage stability of food.
    What is the Composition of Nutrient agar ?Peptone, Beef extract, NaCl, Agar Agar, yeast extract.
    Why agar agar is used to Solidify the media ?Because most of the bacteria on earth can’t utilize agar so media remain solidify.
    What is homogenization ?Homogenization is a process in which fat globule size is reduced to 2500 fat globules under high pressure for its uniform mixing.
    Define Cheese ? Cheese is a fresh or ripened product obtained after coagulation and whey separation of milk.

    What is the effect of too much sugar in Cakes ?

    Too much sugar causes a sticky crust & a gummy texture.

    What’s the purpose of high mixing in high sugar Cakes than low-Sugar Cakes?
    Ans:       To achieve optimum volume during baking and prevent falling when removed from the oven.
    What is meant by rendering?
    Ans:       Rendering is a process by which fat is removed from a
    tissue by heat.
    Examples of Oil in Water are?
    Ans:       Mayonnaise, Butter, Margarine.
    What is the difference b/w Yoghurt and Curd?
    Ans:      Yoghurt:Desired Culture is used
    Curd   mixed culture is used

    What is difference b/w Lassi and Whey?

    Lassi
    Whey

    Contain all soluble and insoluble materials, only fat is removed.

    During Cheese formation Casein is separated and remaining liquid is whey.

    Define Butter?
    Ans:       Fat Concentrate which is obtained by Churning of milk.
    What is the Composition of butter?
    Ans:       Fat                          80-85%
    Moisture                15-16%
    Salt                         2.5%
    Curd                       1%
    Define Ice Cream?
    Ans:       A frozen dairy Product made by suitable blend and Processing of cream and other milk product together with sugar, flavor with or without stabilizer and  color and with the incorporation of air during freezing.
    Differentiate b/w sanitation &-hygiene?
    Ans:      Sanitation:The physical cleaning is simply called sanitation. eg. Proper Drainage, Removal of Waste material etc. The reduction of microbial load upto the maximum possible level ishygiene. It includes cleaning of environment and all the working conditions etc.

    Why some fruit Juices rich in natural colors are notpreserved by SO2?
    Ans:       Because  SO2 bleaches the natural color of the fruit Juices, so fruit Jucies rich in natural colors are preserved by Sodium benzoate.
    What is meant by Smoke Point?
    Ans:       The smoke point is the temperature at which a fat or oil gives off a thin bluish smoke.
    What are the types of separation techniques?
    Ans:       1.             Chromatographic technique

    1. Electromigration technique.

    Define term Chromatography?
    Ans:       Chromatography is a dynamic physical process in which molecular components in a mixture are separated because of their different affinities for two substances referred to as phases, one being fixed or stationary and the other mobile phase.
    What are the types of Chromatography?
    Ans:       1.             Liquid Chromatography

    1. Gas Chromatography

    Enlist Modern Separation Techniques?
    Ans:       1.             High Performance/Precision/Pressure liquid
    Chromatography (HPLC)

    1. Thin Layer Chromatography (TLC)
    2. Gas Chromatography (GC)
    3. Atomic Absorption Spectrophotometer(AAS)
    4. Flame Photometry(FP)
    5. Fourier Transform infrared Photometer (FTIR)

    What is HPLC?
    Ans:       HPLC is high Performance/Precision/Pressure liquid chromatography. It is a separation technique used to separate Non-volatile compounds and high molecular compounds e.g, Antibiotics.
    Define the Term Gas liquid Chromatography (GLC)?
    Ans:      Gas Chromatography is a technique for separating volatile substances by percolating a gas stream over stationary phase is liquid so called gas liquid chromatography. 
    Define the term Electrophoresis?
    Ans:       Separation of substances under high voltage (1.5kv).

    Briefly Explain Spectrophotometery?
    Ans:       UV-Vis light absorbed by the sample as a function of Wavelength and radiated in the form of light spectrum which is detected by Photocathod tube and the signal is recorded.
    What is thin layer Chromatography (TLC)?
    Ans:       TLC is a separation technique in which compounds are separated between two phases namely stationary phase and mobile phase.
    Define the term lipolysis?
    Ans:       The breakdown of fatty material into free fatty acid and   
    glycerol, with the heat of lipolytic enzymes, called                  lipolysis.
    Define the term proteolysis?
    Ans:       Proteolysis is the term that describes the break down of proteinaceous material.
    Briefly explain the term fermentation?
    Ans:       Fermentation is the anaerobic or partially anaerobic oxidation of carbohydrates. During this process enzymes elaborated by microorganism, breakdown carbohydrates or carbohydrate like material into substances that are less subject to undesirable microbial activity than the original material.
    Give the names of industries which are included in fermentation?
    Ans:       Baking, brewing, wine making, vinegar manufacture.
    Enlist the fermented foods?
    Ans:       Yoghurt, Cheese, Sauerkraut, Pickles.
    What is alcoholic fermentation explain with equation?
    Ans:       In this fermentation sugars are converted into ethyl alcohol and carbon dioxide with the help of several yeasts most common according to this equation species of genera (Saccharomyces)
    Yeast 
    C6H12O6    —————->2C2H5OH + 2CO2
    Glucose          
    ethyl alcohol

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