eChapters

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

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

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

Packaging is the integral part and cornerstone of food processing industry. The development of food processing industry goes hand in hand with advancement of packaging technology. Packaging Institute International has defined packaging as “enclosure of products, items or packages in a wrapped pouch, bag, box, cup, tray, can, tube, bottle or other container form to perform one or more of the following functions: containment, protection, preservation, communication, utility and performance”. Lockhart has defined packaging as “a socio-scientific discipline that operates in society to ensure the delivery of goods to the ultimate consumer of those goods in the best condition intended for their use”. Food packaging technology has came a long way from use of anything in hand for wrapping up a product to becoming a key element in product development and design.

1. Introduction

In recent years, consumers have been demanding convenient, healthy and safe foods which have ’fresh-like’ characteristics with a long shelf-life. These demands include important food quality such as appearance, texture, taste and nutritional content which are strongly impacted by the way it is processed. Another major concern among the consumers is food safety and quality. The shelf-life of the food products are mostly influenced due to the action of various harmful microorganisms and enzymes. The conventional food processing technologies, such as thermal treatments (pasteurisation and high temperature sterilisation), evaporation, drying, frying and baking can assure the microbiological safety and/or stability of processed food products, but affects the food quality and nutrients (heat sensitive vitamins, flavour and other bioactive compounds) (Zhang et al., 2019)

1. Introduction

Drying is a thermo physical and physicochemical process, which involves removal of excess water from a solid, semi-solid or liquid food material by evaporating it into vapour phase on applying heat, to reduce growth of microorganism or to completely eliminate their growth. Hence, reducing the water activity increases shelf life of food products. Drying medium for carrying evaporated moisture can be air or steam. Benefits of drying include increase in shelf life, easy to transport, handle food material and reduce packaging cost as it reduces bulk weight. 

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

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.

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. 

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. 

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.

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. 

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. 

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 

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). 

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. 

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. 

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.

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. 

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.