eChapters

Pedigree method of plant breeding is defined as a method of breeding in which individual plants are selected in the segregating generations from a cross on the basis of their desirability judged individually and on the basis of a pedigree record. This has been the most widely used method of plant breeding in all the self-pollinated crops and still continues to be so. This method has been first described by H. H. Lowe in 1927. This is the most widely used method to handle segregating generations following crosses between two parents to develop new cultivars combining desirable traits from both the parents. In this method, superior types are selected in successive segregating generations and a record is maintained of all parent-progeny relationships. The records help the breeder to advance only progeny lines with plants that exhibit genes for the desired traits. Selection begins in F2 generation where individual plants are selected which in judgment of breeder will produce the best progeny in F5/F6 when the selection is finally concluded. In F3 and F4 generations, many loci will have become homozygous and family characteristics begin to appear. By F5/F6 generation, most families are expected to be homozygous and uniform and hence selection within such families is no longer effective. 

Bulk population method of breeding is defined as the growing of genetically diverse populations of self-pollinated crops in a bulk plot with or without mass selection, followed by single plant selection. It is applicable to self-pollinated crops and not applied to cross-pollinated crops. Bulk population breeding is a strategy of crop improvement in which natural selection effect is solicited more directly in the early generations of the procedure by delaying stringent artificial selection until later generations. The Swede, H. Nilsson-Ehle, developed the procedure. H.V Harlan and colleagues provided additional theoretical foundation for this method through their work in barley breeding in 1940s. As proposed by Harlan and colleagues, the bulk method entails yield testing of the F2 bulk progenies from crosses and discarding whole crosses based on yield performance. In other words, the primary objective is to stratify crosses for selection of parents based on yield values. The current application of the bulk method has a different objective.

Single seed descent (SSD) method of breeding is applicable to self-pollinated crops. The method of single seed descent (SSD) was born out of a need to speed up the breeding programme by rapidly inbreeding a population prior to initiating individual plant selection and evaluation while reducing a loss of genotypes during the segregating generations. SSD procedure is based on advancing generations through single seed from each plant in each generation. This separates the inbreeding phase from the selection phase and the population reaches F6 generation faster. This procedure carries forward maximum number of F2 plants to a stage near homozygosity, i.e. F6. It was first proposed by C. H. Goulden in 1941 when he obtained the F6 generation in two years by reducing the number of generations grown from a plant to one or two while conducting multiple plantings per year using greenhouse and off-season planting. H. W. Johnson and R. L. Bernard described the procedure of harvesting a single seed per plant for soybean in 1962. However, it was C.A. Brim who, in 1966, provided a formal description of the procedure of single seed descent, calling it a modified pedigree method.

Backcross breeding is defined as system of breeding whereby recurrent backcrosses are made to one of the parents of a hybrid, accompanied by selection for a specific character or characters. It is basically applicable to self-pollinated crops and is precise way improving varieties that excel in large number of desirable attributes but lack in a few characteristics. This method makes use of a series of backcrosses to the variety to be improved during which character for which improvement is sought is maintained by selection. At the end of the backcrossing, the gene to be transferred remains in heterozygous condition and selfing after the last backcross produces homozygosity for the gene under transfer. As a result, the improved variety will remain like recurrent variety in terms of yield, adaptability, quality features, etc. will be superior for the character which was planned to be transferred from the donor parent.

The application of backcross breeding in plants was first proposed by H.V. Harlan and M.N. Pope in 1922. In principle, backcross breeding does not improve the genotype of the product, except for the substituted gene(s).

The term hybrid or hybrid variety is used to designate F1 populations that are used for commercial plantings. Such F1 populations are obtained by crossing clones, open-pollinated varieties, and inbred lines that are genetically dissimilar. Historically the first attempts to make practical use of fortunate mating system of maize came late in the nineteenth century by W. J. Beal in Michigan, stimulated by Darwin’s work on inbreeding and outcrossing. Beal suggested use of F1 varietal crosses to exploit heterosis for commercial crop. The hybrid seed was to be produced by detasseling alternate rows. It was George Harrison Shull (1909) who first suggested a pure line method of corn breeding based on inbred lines obtained by continued self-fertilization and the use of F1 hybrids between these inbred lines for the production of commercial crop. His proposal was to make use of single crosses (hybrids between two inbred lines) based on the superior performance of the hybrids in various combinations between the inbred lines.

A variety produced by crossing inter se a number of genotypes selected for good general combining ability in all hybrid combinations with subsequent maintenance of the variety by open-pollination. Synthetics development is common in cross- pollinated crops in the early phases of breeding. The synthetic method of breeding is suitable for improving cross-fertilized crops. It is widely used to breed forage species. Successful synthetic cultivars have been bred for corn, sugar beets, and other species like cauliflower in India. The suitability of forage species for this method of breeding stems from several biological factors. Forages have perfect flowers, making it difficult to produce hybrid seed for commercial use. The use of male sterility may facilitate controlled cross-pollination, which is difficult to achieve in most forage species. To test individual plants for use in producing the commercial seed, it is essential to obtain sufficient seed from these plants. The amount of seed obtained from single plants of these species is often inadequate for a progeny test. Furthermore, forage species often exhibit self-incompatibility, a condition that inhibits the production of selfed seed. Synthetic cultivars are also used as gene pools in breeding progeny. Synthetic cultivars are advantageous in agricultural production systems where farmers routinely save seed for planting. One of the well-known and widely used synthetic has been the Iowa stiff- stalk synthetic (BSSS) of maize.

Composites defined as advanced generation populations maintained by random mating in the material constituted through mixing of equal quantity of seeds of crosses showing less inbreeding depression in F2 over F1. The components of composites inbreds, open-pollinated populations, locally available open-pollinated cultivars, hybrids, advanced generation lines, improved populations. Mixing the seeds of several phenotypically outstanding lines produces a composite variety and encouraging open pollination to produce crosses in all combinations among, the mixed lines. The lines used to produce a composite variety are rarely or not tested for combining ability with each other like as done in case of synthetics where the combining ability of the component lines is invariably tested for GCA. Composite are commercial varieties and are maintained by open - pollination in isolation. While mixing the seeds of various genotypes, care should be taken that the component lines are similar in maturity height, seed size, colour, etc. so that the composite maintained through random mating in isolation manifests a reasonable degree of phenotypic uniformity. The variety is maintained by open pollination. Farmers can use their own seed for 3 to 4 years.

Recurrent selection is a method of breeding applicable to cross-pollinated crops, designed to concentrate favourable genes scattered among a number of individuals by selecting in each generation among the progeny produced by mating inter se of the selected individuals (or their selfed progeny) of the previous generation. The concept of recurrent selection grew out of need to increase the number of superior genotypes that could be obtained from breeding stock of corn. This could have been possible by increasing the frequency of superior genes in the gene pool and by increasing the chances for genetic recombination to occur. The original idea behind recurrent selection was proposed first by Hayes and Gerber in 1919 and independently by East and Jones in 1920. Jenkins (1940) was the first to describe the method in detail and Hull (1945) proposed the name ‘recurrent selection’. Each cycle of recurrent selection requires:

Mutation is defined as a sudden heritable change in gene or in chromosome structure. The process of hereditary change is termed mutation and the individuals affected by the change are called mutants. Besides recombinations, mutations are the cause of genetic variation from which every breeding activity proceeds. By means of mutations, the multiplicity of the types of a population is not only increased by one genotype, but also by large number of further new genotypes due to possibility of subsequent recombinations of mutant with the existing genotypes.

Any organism with other than two basic sets of chromosomes, that is, monoploid, triploid, tetraploid, and various aneuploids is termed as polyploid. There are several economically important crops which are natural polyploids emphasizing the economic importance of polyploids in agriculture. These are:

Triploid-Banana

Autotetraploid-Alfalfa, potato, coffee, peanut or groundnut Autohexaploid- Sweet potato

Amphidiploid/allopolyploid-Wheat, cotton, oats, Brassica species (B. carinata- Ethiopian mustard, B. juncea-Indian mustard, B. napus--rapeseed), sugarcane

Man-made commercially successful allopolyploid- Triticale

Reproduction by asexual means is common among higher plants. The best known means of asexual reproduction are by corms, bulbs, rhizomes, stolons, or other vegetative organs. Plants normally propagated in agricultural practice by these means or by budding or grafting include nearly all fruit and nut trees, strawberries, blackberries and raspberries, grapes, pineapples, almost all ornamental shrubs and trees and a few field crops such as sugar cane, potatoes, and sweet potatoes. Asexually or clonally propagated plants produce genetically identical progeny. Clones are identical copies of a genotype. Together, they are phenotypically homogeneous. However, individually, they are highly heterozygous and segregate widely upon sexual reproduction. This is not unexpected, because the types selected as commercial cultivars are likely to be vigorous ones, and a positive correlation exists between vigour and heterozygosity in most species.

Biotic stresses include diseases and insect pests which cause serious damage to the crop plants and ultimately yield loss. Biotic stresses can be listed as follows:

• Diseases caused by pathogens which include fungi, bacteria, and viruses
• Insects
• Nematodes
• Parasitic weeds

Another category of stresses are called as abiotic stresses which are caused by environmental factors as:

• Water stresses (water logging, drought)

Plant abiotic stresses are external and nonliving factors that have harmful effects on plants. A non-living factor must exert influence on the normal range of environmental variation to adversely and significantly affect the plant performance or the physiology of the organism. Abiotic stresses are the most harmful factors affecting the growth and productivity of crops worldwide, resulting in a yield reduction ranging from 10% to 100%. They are most harmful when occurring together with other abiotic stresses and their effect in yield will only worsen with the climatic changes experienced now and expected to be more severe in the future.

Plant breeding or crop plant improvement is one of the oldest accomplishments of man. It began when he domesticated plants by growing them under controlled conditions and selecting those types that suited to his food requirements, about 10,000 years ago. As settlements improved, men could find time to innovate agricultural practices and to have better selections. Thus, domestication of plants and animals marked one of the most important phases in man’s progress from a nomadic and highly individualistic life to the organized and cooperative society. All our food crops as we know them now are the direct results of this primitive agriculture. This early phase of plant breeding was haphazard and slow based on selection of desirable types from the availability variability and it largely remained an art and not a science until Mendel’s laws were rediscovered in 1900 and applied to plant breeding at the beginning of 19^th century. 

The practice of official release of cultivars in India started in October, 1964 with the formation of the Central Variety Release Committee (CVRC) at the Central government level and State Variety Release Committee at State Government level. The Central Variety Release Committee functioned up to 1969 when its functions were taken over by the Central Seed Committee (CSC) established under the Seeds Act, 1966. The Central Seed Committee later on bifurcated CVRC and constituted (i) a Central Sub-Committee on Crop Standards Notification and Release of Varieties for Agricultural Crops and (ii) a Central Sub-Committee on Crop Standards Notification and Release of Varieties for Horticultural Crops to discharge the functions of release/notification, provisional notification and de-notification of cultivars at Central level for field and horticultural crops respectively. State Seed Sub-Committees (SSSC) were asked to discharge similar functions for release at State level. Central Sub-Committee on Crop Standards, Notification and Release of Varieties for Agricultural Crops is responsible for release and notification of field crops. This committee is chaired by ICAR-Deputy Director General (Crop Science). The members are drawn from Directors/Crop Coordinators of ICAR, Directors Agriculture from States, Directors Seed Certification Agencies, Managing Directors of State Seed Corporations, Representatives from Private Seed Companies, etc. 

1.1 Introduction

Horticulture is defined as “The science and art of growing vegetables, fruits, flowers, ornamental plants and landscaping of gardens and surroundings in small and commercial gardens”. The Latin word “horticulture” comprises two parts: “hortus” (which means “garden”) and “cultura” (which means “cultivation”). In other words, horticulture is the nurturing of gardens. Pomology, olericulture, floriculture, and landscaping are the main aspects of horticulture. Horticulture is becoming more and more important since it produces greater output per unit of land and provides humans with nourishing food, improving their quality of life and enhancing the visual beauty of nature. Regarding the worth of the goods, one of the main branches of horticulture is vegetable growing.

Technically speaking, every component of a vegetable is edible. However, the phrase is typically used to refer to edible plants that include reserves of food in the form of roots, tubers, bulbs, stems, petioles, leaves, buds, flowers, fruits, and seeds that can be consumed either cooked or raw. Growing vegetables is crucial not only for supplying food that is protective but also for serving as a substantial auxiliary food that contributes more significantly to food consumption. They are vital parts of a balanced diet since they are nutrient-rich.

2.1 Introduction

Cabbage is consumed in the raw state as well as in cooked. The word cabbage has been derived from the French word Cobache, meaning head which is best described as single large terminal bud comprised of tightly overlapped numerous leaves attached to an unbranched short stem. It is known for its rich source of vitamin A and C. It is an effective curative against scurvy disease. Cabbage leaves are low in calories (24 %), fat (0.2 %) and carbohydrates (5.4 %). It is a good source of protein (1.3 %). Cabbage is an excellent source of minerals such as calcium, iron, magnesium, sodium, potassium and phosphorus. It contains good amount of ascorbic acid. Cabbage is used mainly as a vegetable and nice pickle (sauerkraut) is prepared from it. It is also used as salads. Cabbage is well known for its medicinal properties. 

3.1 Introduction

Cauliflower is a cruciferous vegetable that is naturally high in fibre and B-vitamins. It is said that the cauliflower has originated around the Mediterranean Sea. Ancestor of cauliflower is Brassica cretica which has been descended from the wild cliff cabbage, Brassica oleracea var. sylvestris, a native of coastal region of Europe and Africa. Cauliflower is cultivated worldwide in different climatic conditions ranging from temperate to tropics during most of the cropping seasons and is available round the year. Curd is the economic part of cauliflower and is an intermediate stage between vegetative and reproductive stage. It was introduced in India during the Mughal period. In 1822 a botanist Dr Jemson, In-charge of Company Bagh, Saharanpur, U.P introduced it in India from Kew Garden London. 

Common Name: Ganth gobhi or kadam

4.1 Introduction

Knol khol or kohlrabi is not very widely grown in our country except in Kashmir, West Bengal and some of the South Indian states. Kohlrabi is a herbaceous biennial grown for its edible stem. The edible part in kohlrabi is the tuber formed by the thickening of stem tissue above the cotyledons, i.e., swollen stem called knob or tuber. 

5.1 Introduction

Sprouting broccoli is believed to be the first to be originated from wild cabbage (Brassica oleracea var. sylvestris) or wild cliff cabbage which is found growing wild in southern Europe and along the eastern Mediterranean Sea. It is also known by several other names such as Calabrese or Italian Green because it was cultivated first in Italy by the ancient Romans and spread to other countries only from sixteenth century onwards. In India, it was introduced during the second half of the 20th century. The word broccoli is derived from the Latin word Brachium meaning an arm or branch. Broccoli contains higher amount of protein, vitamin A and C and appreciable quantities of thiamine, riboflavin, niacin, calcium and iron. 

6.1 Introduction

It is an important vegetable in European countries. It got its name from the capital city of Belgium since it has been grown around Brussels for hundreds of years. From Belgium it has been introduced to England (1810). Some parts of Long Island in New York are also well known for Brussels Sprout production. In India, it is widely grown in Kodai kanal and Nilgiris hills of Tamil Nadu and Maharashtra. Exact statistics regarding area, production and productivity are not available. It is a cool, moisture loving and frost resistant biennial, with axillary buds produced in the leaf axils during the first year of growth and a seed head is produced in the second year of growth. Edible part is swollen axillary bud (sprouts or buttons or mini cabbage). 

7.1 Introduction

Chinese cabbage appears to be native of China. It is known to have arisen from a cross between Pak choi (Brassica rapa var. chinensis, non-heading Chinese cabbage) from south China and turnip (Brassica rapa var. rapifera) from north China when they were grown together in the city of Young-chou. Artificial crosses between these species have proved this hypothesis. Its chromosome number 2n=20 distinguishes it from cole crops. It is not a member of cole group but regarded as very closely allied crop due to similarity in breeding systems, cultivation practices, season of growing and other features besides being like a member of Brassica vegetables. In general Pe-tsai cabbage, i.e., heading type (B. rapa subsp. pekinensis or B. pekinensis) and pak-choi cabbage, i.e., leafy type (B. rapa subsp. 

8.1 Introduction

Common onion, Allium cepa L., is a vegetable that is the most widely cultivated species of the genus Allium. It has been cultivated for more than 5000 years. However, its wild species do not exist. Allium is a Greek word. Onion is native of Central Asia. According to Vavilov onion originated in Pakistan, however, others opined it to have domesticated in the mountainous regions of Central Asia comprising Turkmenistan, Uzbekistan, Tajikistan, Afghanistan, Pakistan and north Iran. Jones and Mann proposed the area comprising Pakistan and Iran or South East Asia as the centre of origin. Onion is very important in cookery. 

9.1 Introduction

Garlic (Allium sativum L.) is one of the important bulb crops grown and used as a spice or condiment throughout India. It is derived from two words gar meaning spear and lic meaning herb. It is also important foreign exchange earner for the country. Garlic has higher nutritive value than other bulb crops. It is rich in proteins, phosphorous, potassium, calcium, magnesium and carbohydrates. Healthy garlic bulbs contain allicin, a colourless, odourless and water-soluble amino acid. On crushing the garlic bulbs, the enzyme allinase breaks down into allin to produce allicin of which the principal ingredient is odoriferous diallyl disulfide. Garlic contains about 0.1% volatile oil. 

10.1 Introduction

Leek is a non-bulb forming tetraploid plant of onion family. It belongs to monocotyledons group like onion and garlic, and has white narrow bulbs with broad leaves and etiolated pseudostem formed by the leaf sheaths. Except large size it looks like green onion. Its cultivation is not commercial in India and grown only in kitchen garden. Recently, its cultivation has been noticed in temperate regions of north India and the Niligiri hills of South India. Leek is cultivated for blanched stems and leaves. It is a hardy biennial plant, consumed as salad and used in flavouring the soups. It has flattened leaf blades rather than the radial, and it is bigger than onion. As compared to onion, it has milder and more delicate flavour. 

11.1 Introduction

The word Raphanus has been originated from Greek, meaning quick appearing, refers to its very rapid germination and growth characteristics. It is grown chiefly for its succulent and fleshy edible taproot eaten raw as salad or cooked. The leafy tops are very rich in vitamins A, B and C, and minerals particularly calcium and iron. Major sugar present in radish is glucose. It is a short duration crop and highly productive, so preferred as intercrop or in relay and sequential cropping. 

12.1 Introduction

Carrot is valued as a nutritive food mainly because of high carotene content. The edible part of carrot is modified root (conical form, i.e., enlarged fleshy taproot). Although carrot is a biennial crop but it is grown as an annual for its root. Black carrots (Asiatic carrot root) are used for the preparation of a soft beverage called Kanji, which is supposed to be a good appetizer. Red type is good for preparing various types of sweets especially Gajar Halwa in northern India. Carrot seed oil is used for flavouring liquors and commercially used in France. The taste of carrot is due to the presence of glutamic acid. In carrot roots sucrose is the most abundant than glucose and fructose. Maximum concentration of carotene is found 85-100 days after planting. Carrot seeds contain germination inhibitor named as carrotal. 

13.1 Introduction

Beet root or garden beet or table beet is an important home and market garden crop of India grown during winter season for its fleshy enlarged roots. It can be eaten raw as salad, and cooked with other vegetables. Beet root is rich in minerals and vitamin C. The garden beet, sugar beet, swiss chard, mangel and palak, all belong to the same genus and species Beta vulgaris. Beet root (Chukandar) is not so popular vegetable crop in India. Its root contains high percentage of sugar.

14.1 Introduction

Turnip is quick growing root vegetable. It is a herbaceous biennial for seed production and an annual for use as a vegetable. Both roots and leaves are edible in turnip. Turnip produces napiform types of roots. Turnip is a popular root vegetable of North India grown during winter months. In young stage, it can be cooked but when it is mature, it may become fibrous and hard. It can be eaten raw but, for making palatable pickles, only desi types are the best. European cultivars of turnip are sweeter than Indian ones. The turnip greens are rich in vitamin A and C and contain appreciable amount of vitamin B, and also good source of Ca, P and Fe. 

15.1 Introduction

It is an important vegetable grown since long and used as fresh vegetable. It is an important legume vegetable rich in proteins. The crop is usually grown for its green pods which contains immature seed and are cooked as vegetable, alone or mixed with others. It prefers cool weather and it does not grow well during intense heat of the summer season, especially the wrinkled seeded cultivars which are tender, sweet and of much better quality than the smooth cultivars. 

16.1 Introduction

The broad bean is a hardy plant and can withstand sufficiently cold temperatures. It is cultivated on a small scale in India but widely cultivated in Latin America. This is the only bean which is sown in autumn and is grown as a winter crop (in temperate countries). Broad bean is used as green, shelled and dry beans and as a feed for livestock. Plants have distinguishing features like square and erect growing stems which grow up to 30 cm (dwarf cultivars) to 100 cm (tall cultivars). 

17.1 Introduction

Lettuce is one of the most important vegetable crops in temperate countries. However, it occupies an important position for its cultivation in tropical and subtropical countries also. In the world, the largest consumer and producer is USA. Lettuce is also grown on large areas in South Eastern Australia, Japan, China, Israel, Northern Mexico, Chile, Argentina, Brazil and Peru. Probable ancestor of lettuce is Lactuca serriola L. The crop was spread throughout the 

18.1 Introduction

It is a rich source of vitamin A as compared to spinach and carrot. It also contains high quantity of ascorbic acid, manganese and iron. A 100 g of leaves supplies as much essential amino acids as 100 g of any non-vegetarian food like meat and fish. Its succulent leaves and stems make nutritious dish after cooking. The herbaceous annual plants are mildly laxative besides other medicinal values. This is annual for leaf production and biennial for seed production. 

19.1 Introduction

Traditionally spinach or vilayati palak is classified as a pot herb. The word ‘spinach’ has been derived from a Spanish word Hispania. However, the Latin meaning of ‘spina’ is spiny fruit and oleracea means herbaceous garden herb. The edible part of spinach is a compact rosette of leaves which is normally consumed as a cooked vegetable. Sometimes, it is also used as salad along with lettuce and other vegetables. Spinach is highly suitable for hydroponics. 

20.1 Introduction

Asparagus is a herbaceous perennial plant with an erect branched stem growing to 1-3 m height and is grown in large areas in countries like USA, Germany, Spain and France, while India’s contribution is meagre. The tender shoots called ‘spears’ are used as vegetable and in preparation of soup. It is also eaten as salad. The canned and frozen spears are also used as processed foods. Once asparagus starts producing, it continues to give economic yield for 10-15 years. The tender shoots contain a white crystalline substance, asparagine, which is used in medicine as diuretic in cardiac dropsy and chronic gout. It has good potential as fresh vegetable.

21.1 Introduction

Globe artichoke, commonly known as artichoke, is a perennial crop grown for its flower buds. It has thistle like plants. The above ground portion dies each year during winter and again emerges in spring. It is generally propagated by means of suckers or off shoots from the old root stocks and also by dividing the old crown into pieces with a portion of the stem. The buds are harvested before they become loose and fibrous. It is very nutritious as it contains appreciable quantities of proteins, carbohydrates and minerals. It is a herbaceous perennial in which the globular immature flower heads or buds and the edible bracts are used as vegetable. 

22.1 Introduction

Rhubarb is a less popular winter vegetable grown in India and originated from colder parts of Asia. It is cultivated for its large, thick leaf stalks or petioles which are used for sauces and pies. The plant is a herbaceous cool season perennial with large fleshy underground rhizome having a fibrous root system. It is sufficiently rich in vitamin C and contains traces of vitamins A and B₂. It is grown in cooler climatic conditions and is resistant to cold and dry conditions. It is propagated by divisions of crown. Rhubarb is a native of the cooler areas of Asia, probably Siberia but it is grown in Europe and England for its large, thick leafstalks or petioles which are used for sauces. 

1. Introduction

Law of conservation of mass says that material cannot be created nor destroyed, which is the basic fundamentals of physical science. Many engineering analyses involve material balances. These balances are simply accounting processes that account for all material in processes of interest. The material balance is one of the most useful tools fundamental in the “engineering approach” to design new process. The law of conservation of mass tells that the total mass of all material entering any process must equal the total mass of materials leaving plus the mass of any material accumulated in the process.

1. Introduction

Energy balance means keeping an account of how the flow of energy is taking place in and out of any system or process. It helps the engineers to estimate the total energy requirement and identify the area for conservation of energy in any process. In food processing the concept of energy balance is applicable in unit operation such as blanching, drying, evaporation, freezing, refrigeration, distillation, crystallization. The scopes of energy balance in food industry are:

i) Streamlining and reduction of energy consumption in the existing process.

ii) Selection and sizing of any equipment and process.

iii) Economic analysis of alternate process/technology.

iv) Designing new economically viable process/technology

1. Introduction

Movement of fluids from one location to another is an important unit operation in food processing. Various types of systems are used to convey fluids based on their flow behaviour. Understanding fluid flow behaviour is therefore important for designing of fluid flow systems. The fundamental mechanism involved in fluid flow is the momentum transfer occurring in moving fluids during various unit operations (fluid flow, aeration, drying, fluidization, filtration, centrifugation, sedimentation, mixing, etc.). This chapter deals with the basic concepts of fluid flow, viscosity, pressure measurement, conservation of mass and energy, boundary layer, momentum and velocity profile of fluid flowing in a pipe, flow metering devices, and pumps.

1. Introduction

Thermal energy is transferred in the form heat from one body to another through conduction, convection and radiation or in combination of these modes. Some of the examples of heat transfer that occur during various agricultural processing is drying and dehydration, sterilization, pasteurization, evaporation, distillation, to name a few.

The basic equation of conservation of heat can be written as:

Rate of heat in + rate of heat generation= rate of heat out+ rate of accumulation of heat

1. Introduction

Psyohrometrio is the study thermal and physical properties of gas-vapour mixtures. Ambient air is the mixture of dry air and water vapour and some pollutants. The moisture and pollutant content vary from place to place. The amount of pollutant and water vapour decrease with increase in the altitude. The air is completely dry above 10 km altitude. In many unit operations moist air is required and properties of air changes with temperature and pressure. The pollutants has to be removed before using moist air as a process air either by filtration or circulation. So it is necessary to determine the amount of water present in the air and effect of different unit operation on thermal properties and change in the heat and moisture content of mixture.The International Joint Committee of psychrometric data have fixed the composition of dry by mole fraction as: Oxygen: 0.2095, Nitrogen: 0.7803, Argon: 0.0093, Carbon dioxide: 0.0003. The following are the properties of the dry air

Molecular weight    28.966

1. Introduction

Thermodynamics is science of energy and may be defined as “The branch of science which deals with the Interoction between the heat and work is referred as Thermodynamics

’Thermo’ means heat and ’dynamics’ means motion. It deals with energy interaction when work is converted into heat energy or vice versa. Precisely, thermodynamics may be defined as a science which deals with energy transformation from one form to another and dealing with relationship among the properties ofthe system. In power plants, internal combustion engines, boilers, nozzles, diffusers etc. are the example where heat is converted into work. In compressor, turbine, cooling of engines by water, application of brakes in a vehicle etc. are the examples where work is converted into heat.

1. Introduction

Refrigeration may be defined as the process of achieving and maintaining a temperature below that of the surroundings. The aim being to cool some product or space to the required temperature. Refrigerated system or a room system is maintained at a temperature which is lower than the atmospheric temperature. Due to higher temperature of atmosphere, heat enters the system. To keep the temperature of the system constant, heat must be removed continuously from the system. Heat removed must be equal to the heat transferred to the system. One of the most important applications of refrigeration has been the preservation of perishable food products by storing them at low temperatures. Refrigeration systems are also used extensively for providing thermal comfort to human beings by means of air conditioning.

1. Introduction

Cleaning and grading are the first and vital post harvest operations undertaken to remove foreign and undesirable materials such as crop seed, chaff, mud, stones, straws, immature grains, dust, husk and even iron and steel particles from grains as well as fruits and vegetables and to separate the products into various fractions. Generally, the hand threshing and the traditional handling used in most developing countries cause a larger percentage of foreign matter with these crops. Thus, more cleaning is required. Cleaning is essentially a separation process, in which some difference in physical properties of the contaminants and the food units is exploited. 

1. Introduction

Size reduction is applied to all the ways in which particles of the solids are cut or broken into smaller pieces. Size reduction operation of solids is referred to as 'Comminution", some of the common comminutive processes are - crushing, grinding, milling, mincing, and dicing. Breaking down of large sized particles of food substances into smaller particles is a common unit operation in many food processes, e.g. wheat flour, turmeric powder, spices, etc. are mostly used in powdered form. Some ofthe common objectives that are fulfilled by size reduction are:

1. Introduction

Raw milk is an emulsion. It is a mixture of milkfat globules, Solid Not Fat (SNF) and water. Over time, milkfat globule separate out from milk serum and comes to the surface of milk as a layer of cream due to the low density of milkfat or due to heating of milk. When milk is heated rapidly and continuously, some of the water in it evaporates from the surface. This exposes proteins and fat molecules, which bind and dry out and forms a skin like film on the surface. 

1. Introduction

Mixing is a fundamental and widely practiced operation in many fields, such as chemical, pharmaceutical, and food processing industries. The mixture’s primary aim is to increase the homogeneity of the material in bulk (Uhl and Gray, 1986; Patterson et al., 2004). Mixing means the random distribution of two or more ingredients throughout a system, which differs from the term’ agitation,’ which is defined as establishing a particular flow pattern with the liquid, especially in a circulatory motion within a container. Mixing is a necessary step in the context of food processing operations. 

1. Introduction

Freezing is a method of food preservation that involves lowering the temperature below the freezing point of food generally -18 °C or below. During freezing of food the water present in them changes its state to form ice crystals. Human beings in the colder regions have used freezing as a means of preservation since they learnt hunting and gathering foods. The foundation of the modern frozen industry was laid in mid 1920 when Clarence Frank Birdseye, an American inventor used cold brine solution to chill packaged fish and extended it further for quick freezing of meat poultry fruit and vegetables. 

1. Introduction

Milk is a source of abundant nutrition has been a vital part of human civilization since prehistoric times. However, because of its perishable nature, it requires immediate processing to improve the shelf life and safe consumption .With the advancement of processing techniques in dairy and food processing, there is a widespread option being utilized to improve the milk shelf life byeither thermal technologies (pasteurization, sterilization, and ultra-high temperature) or nonthermal technologies (high pressure processing, high pressure homogenization, pulse electric field and ultra sonication). Still, pasteurization and sterilization are the two foremost process is used for milk industries. Pasteurization is the thermal inactivation of microorganisms at temperatures below100°C that enhance the safety and quality of milk and milk products and extends the shelf life to an extent.