Food Science

Definition and scope of food science

Food Science


Food science is the application of basic science and food engineering to study the fundamental physical, chemical and biochemical properties of food and food processing.

Food science was first used to describe the activities involved in moving food from farm to table. This implied the trans formation of raw materials to usable food stuffs, wheat to bread, animals to meat, milk to butter and cheese.

Food science is inevitably drawn into certain aspects of farming on the one hand and into problems of human and animal nutrition on the other. Food science may be applied to develop technological processes designed to produce sophisticated foods to increase the palatability of the consumers. The development of food science and technology that enables foods to be preserved by canning, dehydration and freezing so that they can be produced and processed in those parts of the world best suited to their culture, transported safety half round the world and be made available to distant markets at any season of the year.

Its relationship with food chemistry, food microbiology and food processing:

Food chemistry is the science that studies the composition of the earth and it has been built up mainly from observation and experiment. The rapid growth of the food industry, into big business and the changes in the number of items on the grocer’s shelves, the many ready to eat products, the new control on food additives and the attempts to standardize some food articles, all serve to emphasize the growing importance of the chemistry of foods.

Dependednt os the science of food is on biology, bacteriology and mycology as well as chemistry, it was necessary for all sciences to develop to the point where education (to make clearer) of the complex mixtures encountered in foods become accurate and meaningful. Fortunately research of significance to food chemistry is now appearing not only in journals devoted exclusively to food problems but also in those in the fields of biology, chemistry, engineering and even physics.

The nineteenth century saw the development of ornganic chemistry, analytical chemistry and physical chemistry – all essencitl to thegrowth of food chemistry and our understanding of it. The pace at which discoveries were made and at which advances occurred increased thourghout the century. The field of CHO, began to fit together, proteins mere recognized and many other compounds of importance in food chemistry were studied.

Food Technology: is the used information generated by food science in selection. Processing preservation and utilization of food science affects the consumption of safe nutritions and whole some food. Since food science is a broad conception it contains many other specialization in it such as :

Food Engineering, food Microbiology, food chemistry

Food Engineering deals with the conversion of all raw agricultural ingredients such as wheat to a finished product such as flour or baked goods. It also covers the unit operation mechanism and chemical aspects.

Food Microbiology deals with ecology of food. The role of environment in food spoilage, the presence and nature of micro organisms responsible for food spoilage and the physical, chemical, biological changes brought about by them. Food microbiology also deals with the study of public health and sanitation.

Food chemistry helps in understanding the physical and chemical nature of food  and the changes takes place during processing and storage of food

Food processing deals with the general characteristics of food raw materials, harvesting, assembling and  receiving of raw materials, methods of food preservation, processing objectives including factors influenceing  food acceptability and preferences, packaging and water, waste disposal and sanitation.

The kind of careers that a food scientist might follow include food development, quality control, sensory specialist, flowur chemist, food safety research and education. It si because of food science amazing achievements have taken place in the food industry. It is a fact that the food industry is able on the most part to supply the cheap, healthy and safe food.

Genet

Ecology – relation of plants and living creatures to each other and thieir environment

                         

                        CARBOHYDRATES

Energy that is needed to move, perform work and live is chiefly consumed in the form of carbohydrates. Carbohydrates, primarily starches, are least expensive, easily obtained and readily digested form of fuel.

COMPOSITION

Carbohydrates are organic compounds composed of carbon, hydrogen and oxygen, with the later elements in the ratio of 2:1. The general formula is CnH2nOn. They are viewed as hydrated carbon atoms.

CLASSIFICATION – SIMPLE AND COMPLEX :

Carbohydrates are classified, depending on the number of sugar units they contain, as simple carbohydrate and complex carbohydrates.

Monosaccharides and disaccharides make up simple carbohydrates, called simple sugars containing one and two sugar units respectively. Polysaccharides called complex carbohydrates are structurally larger and more complex than simple sugars. They include starch, dietary fibre and glycogen.

There are two main classes of monosaccharides based on the carbonyl group present in them. They are aldoses and ketoses, aldoses (eg; glucose) containing the aldehyde group (CHO) and ketoses, (eg;- fructose) containing the ketone group (C=O). Aldoses are further divided into trioses, tetroses, pentoses and hexoses based on the number of carbon atoms. The common disaccharides are Maltose, Lactose and Sucrose which on hydrolysis yield two monosaccharide units.

Maltose hydrolysis Glucose + Glucose

Lactose hydrolysis Glucose + Galactose

Sucrose hydrolysis Glucose + Fructose

Polysaccharides have high molecular weight and are insoluble in water. They are in the form of long chains either branched or un branched.

The polysaccharides are further classified into groups depending upon the products they yield on hydrolysis.

Homopolysaccharides yield only one type of monosaccharide units on hydrolysis e.g.:- starch, dextrin, cellulose, glycogen.

Heteropolysaccharides yield more than one type of monosaccharide units on hydrolysis e.g.:- Heparin, Hyaluronic acid.

Heparin is an anticoagulant found in the liver, spleen, lungs and blood. Hyaluronic acid is found in the umbilical cord, synovial fluid and vitreous humour. It has a lubricating action. In tissues it forms an important part of the cementing ground substance.

The sugars are also classified as reducing and non reducing sugar. The reducing property is attributed to the free aldehyde or keto group.

FUNCTIONS

Carbohydrates perform the following functions.

1. Energy:

The principle function of carbohydrates is to serve as a major source of energy for the body. Each gram of carbohydrate yields 4Kcal of energy regardless of its source. In Indian diets 60 – 80 % of energy is derived from carbohydrate.

2. Glucose:

Glucose is indispensable for the maintenance of the functional integrity of the nervous tissue and is the sole source of energy for the proper functioning of the brain. Prolonged lack of glucose may cause irreversible damage to the brain.

3. Protein Sparing Action:

Carbohydrates exert a protein sparing action. If sufficient amounts of carbohydrates are not available in the diet, the body will convert protein to glucose in order to supply energy. Hence to spare proteins for tissue building, carbohydrates must be supplied in optimum amounts in the diet. This is called the protein sparing action of carbohydrates.

4. Fat Metabolism:

Carbohydrates are essential to maintain normal fat metabolism. Insufficient carbohydrates in the diet results in larger amounts of fat being used for energy than the body is equipped to handle. This leads to accumulation of acidic intermediate products called ketone bodies.

5. Synthesis of Body Substances:

Carbohydrates aid in the synthesis of nonessential aminoacids, glycoproteins (which function as antibodies) and glycolipids (which form a part of cell membrane in body tissues especially brain and nervous system). Lactose remains in the intestine longer than other disaccharides and thus encourages growth of beneficial bacteria.

6. Precursors of Nucleic Acid:

Carbohydrates and products derived from them, serve as precursors of compounds like nucleic acids, connective tissue matrix and galactosides of nervous tissue.

7. Detoxification Function:

Glucuronic acid, a metabolite of glucose serves as a detoxifying agent. It combines with harmful substances containing alcohol or phenolic group converting them to harmless compounds which

are later excreted.

8. Roughage of the Diet:

Insoluble fibres known as composite carbohydrates can absorb water and give bulk to the intestinal contents which aids in the elimination of waste products by stimulating peristaltic

movements of the gastrointestinal tract.

Types of Carbohydrates

Carbohydrates can be classified on the basis of their chemical composition. These are the most easily available and the largest set of compounds on the Earth. Based on the complexity of their structures, there are five major classes of carbohydrates. These are described in brief as follows.

Monosaccharides

These are the basic compounds with a cyclic structure consisting of carbon, hydrogen and oxygen in the ratio 1:2:1. 'Mono' refers to single and saccharides means sugar. Glucose, fructose and galactose are types of monosaccharides.

Disaccharides

These carbohydrates mean 'two sugars', which refer to the commonly available types such as sucrose, maltose and lactose. When two monosaccharides bond together by a condensation reaction, they release one molecule of water and a disaccharide is formed. This bond is called a glycosidic bond.

Oligosaccharides

These are carbohydrates with more than two basic types of sugar molecules, usually between three and ten basic units. Their main function in the body is the storage of glucose. Raffinose and stachyose are the main types of oligosaccharides which consist of repetitive chains of fructose, galactose and glucose.

Polysaccharides

These are also called monomers and are composed of thousands of molecules of the basic units of glucose. Carbohydrates stored in the form of starch contain these type of compounds. Amylose, which is a straight chain compound and amylopectin, which is a branched compound, are the most common types of polysaccharides.

Nucleotides

It is another complex carbohydrate which contains many molecules of cyclic sugar. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are complex five sided sugars classified under this category. The difference between RNA and DNA is that the former has one extra hydroxyl group. 

Effect of cooking on starch:

1.      Dry Heat Effect: It leads to dextrinization. It is the process by which the large starch structures enmeshed together is broken down into smaller polysaccharides till dextrins are formed. This process has following effects :

2.      A. Dextrins reduce the thickening power of the starch in the foods.

B. Bring about surface browing and colour to food like toasted roasted and baked products.

C. Changes the flavor as experienced with bread and toast.

D. Changes the texture of final products which become crispon the surface but retain their juiciness and natural flavours.

E . Imparts a delicate sweetness to products

F. Improves digestibility of starch food.

Effect of Moist Heat:

When starch or starchy food is subjected to moist heat the starch granules take up the water and swell. The granular wall burst and the starchy contents spill out to mingle with water to form a solution which is milky in appearance.

Gelation: Even starch has a temperature range with in which the starch becomes more viscous and forms a gel, which resists flow. The process by which it takes place is called gelation.

Gelatinization: gels (viscous mixture) on further heating the solution become transparent and forms a network of amylose, amylopectin and water held together by intermolecular bonds. All the free water gets enmeshed in a matrix indirected by a coating on the back of the spoon. The hot mixture when poured into a mould and allowed to cool, sets into a form structure which when unmoulded retain the shapes of the container. This process is called gelatinization.

Synerisis : When a moulded starch is kept for  a time in the refrigeration or cut and after that put into some hot water for a while so that starts and comes out of the structure which is distributed . This process is reference is synerisis.

Retrogradation : when some cooked gels showing synerisis inhibit further realignment of the amylopectin fractions to further after the structure the process is termed as the retrogradation.

Uses of Starches in Food Preparation:

1.      Thickening: Starch in the form of the corn flour, refined wheat flour, rice flour and arrow root are used for thickening. The gravies, soups, puddings etc.

2.      Binding : in cutlets

3.      Coating: Starches are often used in the form of pabtis to coat food before frying. This gives the products crispness and seals in the flabour by forming a barrier to evaporation of food contents and provides smooth and golden apprearance to the product by any crevices or irregularities on the surface.

4.      Gelling: Provides the gelling in porridge and puddings.

5.      Browning: It provides the browning to the following products such as toast or chappati due to dextrinization.

Sugars

Sugars are classified as

1.      Monosaccharides:- glucose, galactose, fructose

2.      Disaccharides- Maltose, lactose and sucrose

3.      Polysachharides – glycogen, dexrrin, pectin, starch etc.

Uses of sugars:

1.      Candies  - burfies, caramels, chewy and gummy products

2.      Syrup – sugar syrup it may be single thread, two thread or three thread

3.      Crystals – sugar crystals.

4.      Invert sugar – when sucrose is heated in the presence of acid/ enzyme equal amount of dextrose and lacillose are formed this mixture is known as invert sugar