eChapters

1.1 Importance of Food Process Engineering

Food occupies the first position among the hierarchal needs of human beings. It is more important than shelter and clothing. After production and be forec on sumpti on, food commodities are subjected to nume rous unfavourable physical, chemical, microbial or parasitic factors which may cause their spoilage or disease when consumed. To prevent such spoilage, a process engineer has to understand these and provide remedial measures. The two primary goals of processing operation are first to minimize post harvest losses and second value addition of raw food commodities through preservation and processing.

Present level of production of different types of food commodities and their estimated post-harvest losses along with monetary values are given in Table 1.1. It shows that various food items get lost, to the tune of 65 million tonnes, worth Rs. 76,000 crores per annum, during post-harvest phase. A substantial amount of these losses could be prevented if appropriate agro processing centers, having backward linkage with farmers to ensure constant supply of quality raw food materials, are established and operated. Profit generated through value addition must also be shared with farmers, who are only people in the world to create wealth every year, in the form of food, fiber and other commodities necessary for human survival. It can bring sea change in rural areas, where 65-70% population live, in respect of economy, health and happiness.

It sounds simple, but the above process is fairly complex and requires lot of coordination in order to succeed. The major challenge is to minimize the losses during the various post harvest operations and keep the food as fresh as possible. In order to do so, one must first try to understand the various causes of post harvest losses of food commodities and the various factors that influence theses causes. Secondly, we must use those food processing operations that will not only extend the shelf life of the produce but also convert the raw food commodities to more acceptable product to the consumer.

2.1 Introduction

Many complicated engineering principles are to be analyzed and applied, before any food processing operations takes shape of a commercially viable enterprise. The size and type of the required equipments have to be specified and their sequences have to be arranged. Further, the process analysis consists of understanding of material and energy balances. This chapter provides the application of steady state conservation of mass and energy equations to analyze food-processing operations.

3.1 Introduction

The subject of heat transfer is firmly grounded in the sciences of thermodynamics and fluid mechanics. It has become exceedingly important for engineers to possess a clear understanding of the principles of heat transfer and its application to a large number of problems. In view of process engineering, the knowledge of heat transfer and its application is most important, because heat transfer is one of the basic unit operations in the agricultural processing activities. The design of process equipments, refrigerators, boilers or type of heat exchangers, thermal treatment of food grains, cooling of perishables, pasteurizations, sterilizations, freezing of milk and fruit juices and a large number of similar applications involve consideration of heat transfer rates. There may be other situations where heat is being generated during a certain operation, and may be detrimental to the equipment and the food product. In such cases we are often faced with the task of removing the undesirable amount of heat as far as possible.

4.1 Introduction

The food preservation may be define as the state in which the food may retained over a period of time without being contaminated by pathogenic organism or chemicals and without losing its colour, texture, flavour and nutritional value. All the methods of food preservation must provide such an environment in and around the preserved food so that it produces one or more unfavourable conditions to the continued activity of the spoilage agents. The various methods used for food preservations are:

5.1 Introduction

The medium used in various unit operations of food process engineering such as heating, cooling, drying, mixing and transport processes, is moist air, which is a mixture of two substances. One of these is dry air which itself is a mixture of number of gases and the other is water vapour which may exist in a saturated or superheated state. The properties of moist air are called psychrometric properties and the subject, which involves determination of thermodynamic properties of moist air, is known as psychrometry. Thus, psychrometry is that branch of engineering science, which deals with the study of moist air i.e. dry air mixed with water vapour or humidity. Knowledge of properties of moist air is imperative in design of systems such as air- conditioning equipment for storage of fresh produce, dryers for drying of cereal grains, and cooling towers in food processing plants. In this chapter, important thermodynamic properties used in psychrometric computations are defined. Psychrometric charts useful in determining such properties are presented. In addition, various psychrometric process used in food process engineering are discussed.

6.1 Introduction

In general, the terms drying and dehydration are interpreted as the removal of moisture from a food product. Removal of moisture from a food product offers an excellent protection against most common causes of food spoilage. The drying or dehydration process achieves such protection by reducing the moisture content of the food product to levels which are adequate to limit microbial growth or other adverse chemical reactions. During drying, heat and mass transfer occur simultaneously (Figure 6.1). Heat is transferred from the bulk gas phase (i.e. hot air used for drying) to the solid phase (i.e. food product to be dried), where part of it is utilized for vaporization and the remainder is taken up by the solid phase as sensible heat. Mass (i.e. moisture of food product) is transferred in the form of vapour through various resistances, first from the interior of the solid to the surface, then through vaporization at or near the surface and finally in transport of the vapour into bulk gas phase. Dehydration is the removal of moisture close to bone dry condition.

7.1 Introduction

Evaporation is an unit operation which converts a liquid into a vapour, leaving behind a concentrated solution or a higher boiling liquid. In other words, the goal of evaporation is to vaporize most of the water from a solution containing a desired product. Heat is the main tool in evaporation, and the process occurs more readily at high temperature and low pressures. Removal of water from foods provides microbiological stability, reduces deteriorative chemical reactions, and reduces transportation and storage costs. Evaporation can be distinguished from some other drying methods in that the final product of evaporation is a concentrated liquid, not a solid. It also differs from distillation, since the vapours produced in the evaporator are not further divided into fractions.

It is well known that lowering the temperature of food stuffs reduces microbiological and biochemical spoilage and thus extending the shelf life of the product. In addition, it is generally agreed upon that the reaction rate is reduced by half by lowering the temperature by 10°C. Though low temperature preservation process has been recognized as a preservation technique for several hundred years, the major developments in its utilization have occurred only in the last century.

The various unit operations of food process engineering applied to solve the problem of changing the compositions of solutions, mixture and solids. Often these operations must be conducted on large scale to meet the demands of a large manufacturing plant. In food processes engineering these operations are often referred to as separation / concentration / extraction / purification process. Usually these operations are directed towards separating substances into its component parts or concentrating a particular substance from another.

10.1 Introduction

Milk is a unique substance in that it is both consumed, as fluid milk with minimal processing and it is the raw material used to manufacture a wide variety of products. From the nutrition point of view, milk is an almost ideal food and considered to be perfect food. The human body needs more than thirty distinct materials in its food supply. No single food stuff supplies all of them but milk supplies nearly all. Since milk by its nature is perishable and an ideal product for bacterial growth, so it must be carefully handled, both during production and while processing. This chapter focuses on the technological (processing) aspects of the transformation of milk into its various consumer products, including beverages, fermented products, concentrated and dried products, butter and ice cream.

Abstract

Food is basic need of human for its existence. Food is a source of nutrients needed for growth, energy and protection. There are number of chemical compounds not considered as nutrients but has positive effect on health. There is a need to look into the health benefits of the food components. Many lifestyle diseases are caused by the unhealthy food habits. Developments in science have led to establish the link between food intake and healthy living. Non-nutrient compounds of food are also called phyto-chemicals. Functional foods are prepared by increasing a particular nutrient or phyto-chemical to get health benefits. The increased cost of health care and drugs trigger the developments in this area. The approximate global market size is 30 billion US$ while Japan, United States, and Europe are the leaders in functional foods. FICCI has reported that functional food market in India is worth Rs 4,400 crore with growth rate of 21%per annum.

Introduction

The food has been considered as source of nutrients in the past but increasing evidences has proved that particular types of food can help in preventing the diseases. The World Health Organization (WHO) has reported that deaths due to Non-Communicable diseases are increasing in South East Asian counties; where as CMPN (Communicable, Maternity, Prenatal, and Nutrition) are

Production: According to Food and Agriculture Organization (FAO) of United Nation, the global production of fruits and vegetables including melons was 638 and 1090 million metric tons while India produced 75 and 106 million metric tons in 2011. In addition to this, the world production of roots and tuber was 810 million metric tons whereas India produced 51 million metric tons in 2011. It indicates that fruits and vegetables form an important part of the diet in the world including India. There is an ample opportunity to manufacture various health promoting products based on fruits and vegetables. A number of Fruits and Vegetable based functional food that can be prepared and presented in (Table 1) indicates the role of fruits and vegetables in the nutraceutical production for their health benefits.

Abstract

Designer foods are known by various names like medical foods, fortified foods, nutritional foods, nutraceutical foods, pharma foods etc. These foods are nutritious, maintain health and prevent diseases. Such foods must possess characteristics like modified composition; limit the presence of certain potentially harmful components and include certain desirable ingredients either naturally or by intentional addition. The term designer food emerged some years ago to describe foods tailored to specific concentration and proportion of nutrients that are important to health. These are designed and produced by using different approaches. The term ‘designer foods’ is subjected to change based on nutritional labelling regulations, new developments, consumer perceptions and expectations. Grain improvement through biotechnology emphasizes crop upgrading with a specific challenge to manipulate the endosperm composition in order to improve its intrinsic properties for diet and health. Breeding fruits with higher bioactive compounds for disease resistance and improved composition have stimulated interest in the nutraceutical and processing aspects of the fruits Nutritive and genetic interventions to alter milk composition for specific health and processing opportunities are gaining importance in dairy biotechnology. Designer eggs having modified fat provide choices with different nutritional benefits. The options suggested for designer meat and meat products are through production practices, post-harvest procedures and reformulation techniques. All these features of designer foods will be presented with suitable examples.

Introduction

Whey is the serum or watery part of the milk that remains after separation of curd that result from the acid or proteolytic enzyme mediated co-agulation of milk. It is major by product of dairy industries manufacturing products like channa, paneer, cheese and chakka (Sharma and Bhatia, 1999).The current world production of whey is estimated at about 165 million tones, in that cheese whey accounts for nearly 95 % of total whey. In India near about one million tonne of whey is annually derived, in that major source of whey is from the production of channa, paneer and shrikhand production. This is mostly thrown away as a waste which creates environmental pollution, also in that way about 70, 000 tonnes of Nutritious solids are lost (Puranik, 1999).

Abstract

Research has demonstrated that nutrition plays a crucial role in the prevention of chronic diseases as most of them can be related to diet. Functional food enters the concept of considering food not only necessary for living but also as a source of mental and physical well-being contributing to the prevention and reduction of risk factors for several diseases or enhancing certain physiological functions. One of the most clear objectives of the study of functional foods is to identify and validate biological markers in order to understand the interaction mechanisms between the food component and a body function. Epidemiologic and laboratory data from previous studies suggests that diets rich in fruits and vegetables are associated with a reduced risk of various types of cancers. The reduction in cancer risk may be attributed to the abundance of a family of specific compounds referred to as anthocyanins, which are found in various berries. Anthocyanins are water soluble pigments responsible for the blue, purple, and red color in many plant tissues Strawberry is one of “super fruits”, since they can form a significant component of the diet and are a potential resource of functional foods and nutraceuticals due to their antioxidant capacity and nutritional quality. Strawberries contain high levels of anthocyanins and they are also well liked by consumers. Popularity of strawberries in the consumer market makes them an ideal focus for chemoprevention studies. Strawberries are a rich source of phytochemicals (anthocyanins, catechins, the flavonols quercetin and kaempferol, and ellagic acid) and an important source of essential nutrients (ascorbic acid, potassium, folic acid, carotenoids, B-vitamins). Strawberries are consistently ranked among the top food sources of polyphenols and antioxidant capacity; the preventive and therapeutic health benefits of strawberries may be attributed to the synergistic effects of these bioactives and the nutrients contained in the fruit. These bioactive photochemical contribute the major health-promoting function. Strawberries have shown a remarkably high scavenging activity toward chemically generated radicals, thus making them effective in inhibiting oxidation of human low-density lipoproteins. Antioxidant activity of strawberries could contribute to the prevention of cancer, cardiovascular and other chronic diseases. Hence strawberry can be used as a vital and indispensible functional ingredient for the development offunctional foods and nutraceuticals.

Abstract

The production of natural food colours through bio-processing is preferred now-a-days due to health related issues associated with their synthetic counterparts. Microorganisms are generally preferred sources as these have high production rate, high growth rate, ease of handling under controlled conditions and absence of seasonal variations. Biopigments can be produced from different genera of bacteria, yeast and mold. Different types and colours of pigments have been produced from microorganisms depending upon their origin, media components and process conditions. The biopigments have variety of applications in food industry such as food additives, food preservatives, biological control agents and nutritional supplements. These have also been associated with therapeutic, and antioxidant properties. Lycopene from B. trispora is used as a food ingredient in dietary supplement. Astaxanthin from X. dendrortious has also been reported to have beneficial effect on human health as it possesses strong antioxidant properties. Arpink red P. oxalicum is used as red colorant in meat products, non-alcoholic drinks, milk products and confectionary. 0- carotene is considered as leading food colorant in world and is applied to range of baked, dairy and canned foods to improve their appearance. The antioxidant andprecursory properties of0-carotene increase its applications in pet foods. Zeaxanthin is used as additives in poultry fed to intensify the colour of the egg yolk. Monascus pigments are utilized for coloration of sausages, ham, marine products and tomato ketchup. Monascus extract is also marketed as dietetic supplement in Japan. Thus, the biopigments can serve as a chromophore for colorant production with broad spectrum of colours and wide applications.

Abstract

The aim is to review the potential health benefits of minor millet. There is in need to identify newer sources of nutraceuticals and other natural and nutritional materials with the desirable functional characteristics. They are an important staple food in India for people of low income groups. Minor millet is rich in several nutrients as well as non-nutrients such as phenols. Nutritionally, its importance is well recognised because of its high content of calcium (0.38%), dietary fiber (18%) and phenolic compounds (0.3-3%). Minor millets, one of the cereals are known for several health benefits including its polyphenol and dietary fiber contents. Health beneficial effects include anti-diabetic, anti-tumerogenic, atherosclerogenic effects, antioxidant and antimicrobial properties. The energy of minor millets is greater than other cereals and nearly equal to that of brown rice because the lipid content is generally higher (3 to 6%). This review deals with the nature of polyphenols and dietary fiber of minor millets and their role with respect to the health benefits associated with millet.

Abstract

Micronutrients and bioactive compounds must be part of the population's diet in sufficient amounts to meet the body's needs. The concentrations of micronutrients and bioactive compounds in plant foods at harvest are known to vary with such factors as the variety or cultivar, stage of maturity, geographic or climatic effects, etc. Most subclasses of polyphenols e.g., phenolics acids and flavonoids, the effects of processing on the contents were found negligible in comparison to the differences between varieties of plants but carotenoids are among the food components most affected by environmental and processing conditions. Thermal processing has long been known to cause significant losses of vitamins, carotenoids and anthocyanins. The heat treatment viz. blanching, pasteurization, sterilization etc. result in losses of thermally labile nutrients and bioactive compounds, but the inactivation of oxidative and other degradative enzymes (e.g., lipoxygenase for carotenoids, polyphenol oxidase for flavonoids, ascorbic acid oxidase for vitamin C). Nutrients in dehydrated products are more likely to undergo degradation during storage because of the greater surface area exposed to oxygen and light. Blanched products generally resist decomposition better than unblanched foods during storage. Compared to losses during processing, subsequent storage often has a small but significant effect on vitamin and bioactive compound contents. Reaction rates are relatively slow at ambient or reduced temperature. The processing method chosen, and storage condition applied finalise the retention of these compounds which decreases with longer processing time, higher processing temperatures and storage of the food.

Abstract

Health benefits of aloe vera include its application in wound healing, treating burns, protection against skin damage, lung cancer, intestinal problems, increasing high density lipoprotein (HDL), reducing low density lipoprotein (LDL), reducing blood sugar in diabetics, fighting acquired immune deficiency syndrome (AIDS), allergies and improving immune system. Phytochemistry of aloe vera gel has revealed the presence of more than 200 bioactive compounds. Aloe vera gel is extracted from its leaves and appropriate processing techniques are needed for stabilization and preparation of the food products. Aloe vera gel products have become available in our country for internal consumption as a tonic and diversification in its products is on progress. The use of aloe vera has gained popularity because of herbal movement initiated by naturopaths, yog gurus, alternative medicine promoters and holistic healers. A recent market analysis report indicates that Americans have spent almost 40 billion dollars on functional foods, drinks and supplements for the improvement of their appearance as well as to provide energy and added nutrition to handle health issues such as hypercholesterolemia and diabetes.

Abstract

Upcoming era of functional foods has led food scientists and food processors to deeply understand the role of phytochemicals in promoting human health. Phytochemicals are the secondary metabolites produced by plants and are commonly found in our daily food. Natural food products seem to be good substitute for pharmaceutical supplements to improve health status of people. Therefore, consumer's interest is growing in the food items naturally containing phytochemicals, each having there own functional and health aspects. Most discussed phytochemicals in the present paper are carotenoids such as lycopene, beta-carotene, lutein and, polyphenols such as phenolic acids, flavonoids, anthocyanins and isoflavones. Major dietary source for carotenoids include orange and yellow fruits and vegetables as well as green leafy vegetables whereas polyphenols are found abundantly in green tea, wine, berries, cocoa, broccoli. Carotenoids can also be used as colorants in foods during processing. The role of polyphenols as an antioxidant is well characterized because of there ability to scavenge free radicals or bind pro-oxidant metal ions by means of their hydroxyl group. Carotenoids also play an important role in protection against photooxidative processes by acting as singlet molecular oxygen as well as peroxyl radical scavengers, thus acting as potent antioxidant. Apart from antioxidative properties multitude of health benefits are associated with carotenoids and polyphenols such as reduced risk of age-related macular degeneration, certain cancers such as prostate, lung and colon, prevention of cardiovascular disease and enhancing immunity towards infection. Hence, continuous developments are being made to combine phytochemicals to avoid improper combinations that may nullify the effect of supplements and cause lower absorbance.

Abstract

Dietary fibers mostly include non-starch polysaccharides such as celluloses, hemicelluloses, gums and pectins, lignin, resistant dextrins and resistant starches. Based on their water solubility, dietary fibers may be divided into two forms insoluble dietary fiber which includes celluloses, some hemicelluloses and lignins which is fermented to a limited extent in the colon and soluble dietary fiber which includes f-glucans, pectins, gums, mucilages and hemicelluloses that are fermented in the colon. Resistant starch generally considered to be represented by the total amount ofstarch and the product of starch degradation that are not digested in the small intestine andpass into large intestine, and regarded as a component ofdietary fiber. Herbal nutraceutical is used as a powerful instrument in maintaining health and to act against nutritionally induced acute and chronic diseases, thereby promoting optimal health, and quality of life. Dietary spices in their minute quantities has an immense influence on the human health by their antioxidative, chemopreventive, antimutagenic, anti-inflammatory, immune modulatory effects on cells and a wide range of beneficial effects on human health. Nutraceutical is the hybrid of ‘nutrition’ and ‘pharmaceutical’. Nutraceuticals, in broad, are food or part of food playing a significant role in modifying and maintaining normal physiological function that maintains healthy human beings. Functional foods are including whole foods and fortified, enriched, or enhanced foods or dietary components that may reduce the risk of chronic disease and provide a health and physiological benefit beyond the traditional nutrients it contains.

Abstract

The concept of functional foods has received significant media attention and, as a result, interest has focused on the need for research into the non- nutrient constituents of food plants. This has enabled market penetration of functional foods containing increased amounts of bioactive food compounds or physiologically active nutrients and non-nutrients within food that impart proven health benefits. Functional foods can take many forms. Some may be conventional foods with bioactive components that can now be identified and linked to positive health outcomes. Some may be fortified or enhanced foods, specifically created to reduce disease risk for a certain group of people. Numerous observational studies have shown that omega-3 fatty acids enriched diets are associated with a reduction of cardiovascular mortality, heart attack and sudden death. In several studies, a higher fish intake has been associated with decreased incidence of coronary artery disease (CAD) and cardiovascular mortality. A trial revealed that fish oil supplementation of 130 mg/kg of body weight each day decreased the number of stiff joints, duration of morning stiffness, pain and global arthritis activity. Many supplements contain active ingredients that have strong biological effects in the body. The bioavailability of nutrients within a given food is governed by the composition and microstructure of the food, commonly referred to as the food matrix. More specifically, numerous studies investigating the development of functional foods have shown that the interactions between nutrients and non-nutrients within the food matrix can be synergistic, additive, or neutralizing in nature. The preventive and curative effects of the functional foods on health concludes it to be integral components of established public health programs to reduce the risk of specific diseases.

Abstract

The gut microbiota, microbe population living in the human large intestine is generally associated with various metabolic functions and it influences health and well-being. Taking into account the major role gut microbiota play in the normal functioning of the body and the different functions it accomplishes, experts nowadays consider it as an “organ”. However, it is an “acquired” organ, as babies are born sterile; that is, intestine colonisation starts right after birth and evolves as we grow. Each of us has a unique microbiota, as the fingerprints, it always fullfils the same physiological functions and they have a direct impact on our health. Gut microbiota consists of a complex of microorganism species that live in the digestive tracts of animals and is the largest reservoir of microorganisms mutual to humans. Gut microorganisms benefit the host by gleaning the energy from thefermentation of undigested carbohydrates and the subsequent absorption of short-chain fatty acids. The most important of these fatty acids are butyrates, metabolised by the colonic epithelium; propionates by the liver; and acetates by the muscle tissue. The human body carries about 100 trillion microorganisms in its intestines, a number ten times greater than the total number of human cells in the body Guarner and Malagelada, 2003). Gut microbiota, particularly the probiotics, have beneficial effects on gastroenteritis resistance, blood lipids, antitumor properties, lactose tolerance and gastrointestinal immunity. Probiotics have role in reducing the risk of rotavirus-induced diarrhea and colon cancer. The survivability of any probiotic bacteria till a longer time in the gut can be enhanced by the supplementation of prebiotics. Prebiotics are non-digestible food ingredients that benefit the host by selectively stimulating the growth or activity of one or a limited number of bacteria in the colon. There are so many prebiotics which stimulate the growth and survivability of probiotic bacteria such as fructo-oligosaccharide (FOS), inulin, galacto-oligosaccharide (GOS), polydextrose (PDX), acacia gum (GUM), lactulose (LOS), lactitol etc. Many research studies have been done on above mentioned prebiotics. Mostly inulin-type fructans have been used as functional food ingredients. The prebiotics are known for reduction of disease risk such as constipation relief, suppression of diarrhea and reduction of the risks of osteoporosis, atherosclerotic cardiovascular disease associated with dyslipidemia and insulin resistance, obesity and possibly type-2 diabetes. Probiotics are beneficial microbes that confer a realistic health benefit on the host, which in combination with prebiotics, (indigestible dietary fibre/carbohydrate), also confer a health benefit on the host via products resulting from anaerobic fermentation. The combination of probiotics and prebiotics in a synbiotic might improve the survival of the bacteria crossing the upper part of the gastrointestinal tract, thereby enhancing their effects in the large bowel and immune-modulatory ability.