eChapters

Abstract

The conventional methods of pathogen identification have often depended on identification of disease symptoms, isolation and culturing of the organisms, and identification by morphology and biochemical tests. The major limitations of these culture based morphological approaches, however, are the reliance on the ability of the organism to be cultured, the time consuming nature and requirement of extensive taxonomic expertise. Furthermore, diagnosis of plant diseases can be even more difficult with asymptomatically infected propagative materials such as tree grafting stocks or potato tubers. The use of molecular methods can circumvent many of these shortcomings. Accordingly, there have been significant developments in the area of molecular detection of plant pathogens in the last three decades. The polymerase chain reaction (PCR) which revolutionised molecular diagnostics and biological sciences. In the last decade the range of targets that can be diagnosed using diagnostic PCR have grown tremendously. The very flexibility and application specific variations in the basic theme of the system have allowed the development of many PCR variants adapted to wide range of applications. Furthermore, diagnostic PCR has been greatly improved by the introduction of the second generation PCR, known as the Real time PCR where closed-tube fluorescence detection and quantification during PCR amplification (in real time) is possible eliminating the need for laborious post-PCR sample processing steps which greatly reduces the risk of carryover contamination. Using Real Time PCR, it is possible not only to detect the presence or absence ofthe target pathogen, but it is also possible to quantify the amount present in the sample allowing the quantitative assessment of the number of the pathogen in the sample. Enumerating the pathogen upon detection is crucial to estimate the potential risks with respect to disease development and provides a useful basis for diseases management decisions. Crops can be attacked by many pathogens which, in addition, often occur in complexes. Therefore, many disease diagnostic applications require simultaneous detection and quantification of several targets. Methodological limitations, however, are in many cases the reason for developing simplex or assays designed for only few targets. The DNA Microarray technology, originally designed to study gene expression and generate single nucleotide polymorphism (SNP) profiles, is currently a new and emerging pathogen diagnostic technology, which in theory, offers a platform for unlimited multiplexing capability. It is viewed as a technology that fundamentally alters molecular diagnostics. The fast growing databases generated by genomics and biosystematics research provides unique opportunity for the design of more versatile, high-throughput, sensitive and specific molecular assays which will address the major limitations of the current technologies and benefit plant pathology.

Abstract

Ber is an important fruit of India and South Asia. Its cultivation is gaining popular in recent years. The drupaceous fruits of ber are characterized by climacteric respiration phenomena and produce high amount of ethylene at ripening. It is very high in ascorbic acid content. Maturity and ripening is still judged by colour changes, as reliable maturity indices for particular cultivars are not fully established. Short shelf life is major problem in this fruit. Protocols for postharvest handling is not standardized, however, scattered information are available for postharvest behaviour and handling. Low temperature storage is beneficial and reduces respiration rates but simultaneously chilling injury is again hindrance in commercialization. Postharvest rot is major problem in storage. Therefore, focused research is needed to standardize the storage temperature and alleviation of chilling injury.

Abstract

Molecular markers play key role in crop improvement. There are severalmarkers such as RAPD, SSR, AFLP, SNP, DArT and many more are available for their practical uses. From the past markers like RAPD, AFLP, and SSR have been used extensively in the crop breeding. Recently new markers such as SNP and DArT have become popular among the researchers of molecular biology for use in genomics-assisted crop breeding. These markers have been applied for study of genetic diversity, germplasm management, cultivar identification, genetic mapping, gene tagging and genomics etc. Though the conventional method of breeding willcontinue to play a primary role in the crop improvement, molecular marker technology is becoming one of its integral components. Agarose-based DNA markers like ISSR, CAPS, RAPD, SCAR and AS (allele specific) have the potential for faster and accurate breeding for target traits through MAS.

Abstract

Health-conscious consumers are increasingly seeking functional foods in an effort to control their own health and well-being. The field of functional foods, however, is in its infancy. Claims about health benefits of functional foods must be based on sound scientific criteria. A number of factors complicate the establishment of a strong scientific foundation. These factors include the complexity of the food substance, effects on the food, compensatory metabolic changes that may occur with dietary changes, and, lack of surrogate markers of disease development. Additional research is necessary to substantiate the potential health benefits of those foods for which the diet-health relationships are not sufficiently scientifically validated. Research into functional foods will not advance public health unless the benefits of the foods are effectively communicated to the consumer. Finally, those foods whose health benefits are supported by sufficient scientific substantiation have the potential to be an increasingly important component of a healthy lifestyle and to be beneficial to the public and the food industry. Mounting evidence supports the observation that functional foods containing physiologically-active components, either from plant or animal sources, may enhance health. It should be stressed, however, that functional foods are not a magic bullet or universal panacea for poor health habits. There are no “good” or “bad” foods, but there are good or bad diets. Emphasis must be placed on over-all dietary pattern, which follows the current Dietary Guidelines, and is plant-based, high in fiber, low in animal fat, and contains 5-9 servings of fruits and vegetables per day.

Abstract

Fertilizer inputs are increasing the cost of production in inputintensive crops, so nutrient efficientcultivar is need oftoday. More demands for food by increasing world populations further enhance the importance of nutrient efficient crop cultivars that are higher producers. Breedingtechniques havebeenimplemented significantlyto breed highnutrientefficient crop cultivars to achieve the targets. However, molecular mechanism of nutrient metabolism has been understood to some extent in many crops through quantitative genetic approaches. This minireview outlines an update on recent progress on the genetic approaches of QTL/candidate genes controlling nutrient metabolism pathways in the crop plants.

Abstract

Bioinformatics is a field of science which studies biology, computer science, and information technology. The ultimate goal is to obtain useful information by data acquisition, analysis and interpretation of sequences data. In the current decade, a huge volume of sequence data is stored in the data bank due to global genome initiatives of many organisms. Management and understanding of the genome data cannot be possible without the bioinformatics tools. A large number of tools and softwares packages are available either commercial or freely online for the bioinformatics applications. The use of bioinformatics tools enhances the research capability for crop improvement through genome sequencing, database management, assembly, alignment, primer designing, markers development, genes prediction and annotation, gene expression, phylogenetics, protein structure identification, metabolic pathways analysis and many other applications.

Abstract

Issues regarding intellectual property rights and their protection are heralded nowadays in the scientific arena both in developed and developing countries. IPR is being given greater attention and importance due to the projected idea that it is a dependable means through which greater skills and knowledge can be utilised to serve as a reliable resource for the upliftment of the economy as well as knowledge dissemination. In context of microorganisms, India does not allow patenting of microbes whichalready exists in nature assuch but genetically modified version of the same microorganism with enhanced and improved efficacy can be patented. The deposition of microorganisms in a culture collection recognized as an international depository authority (IDA) is necessary if intellectual property rights regarding these microbes are to be claimed. An action plan for developing countries towards creating IDAs and preserving the natural gene pool has been evolved. It is likely that IDAs will transform into ‘biological resource centres’ and further into‘global common genetic resources’, with an internationally agreed legal basis for benefit sharing. This chapter is an effort to highlight the genesis of patenting and legalities of patenting microorganism in India.

Abstract

Potato in India was introduced as a long day temperate crop which found suitable climate in the higher hills of the country. Since then it is grown widely in the Indo-Gangetic Plains, the Plateau and the Himalayan regions in north and the Nilgiris hills in south of India. The Central Potato Research Institute (CPRI), Shimla has developed 49 potato varieties by the conventional breeding for suitable cultivation of potato in different potato zones of India. A number of technologies for ware- and quality seed- potato production, storage and processing have been developed/standardized for adoption by the end users. These technologies have contributed immensely towards multiple increase in area, production and productivity of potato during last sixty years. Apart from conventional tools, modern biotechnological tools like whole genome sequencing technology, transgenics technology, molecular markers, RNAi and microarray technology have are also being employed in potato improvement.

Abstract

In the present horticultural scenario of India, this is the burning issue as how best the underutilized horticultural crops can be exploited. There is tremendous potential for these crops especially for diversification. These plants can generate employment for millions especially to the natives ofdeveloping counties besides nutritional security. Traditional wisdom of Indian farmers if used properly can pave the path for transforming the economy of developing nations. There are great opportunities for the people to identify crops, explore their market, standardize their cultivation and processing techniques, document them and provide jobs to millions. This will salvage the people from exploitation by multinational companies of developed nations and can give a new direction to sustainable agriculture.

Abstract

Genomics is playing an increasing role in generating new tools and databases with the rapid advances in genome technology which increases the eficiency and precision of crop improvement. With the emergence of new high-throughput technologies like next-generation sequencing (NGS) and reduction in their costs are bringing many more plants within the range of genomic and post genomic data along with the integration of information from the related fields of transcriptomics, proteomics, metabolomics and phenomics. Translating the vast abundance data produced by genome technologies requires large generic databases which hold specific data types for a broad range of species, which act as a resource for the crop improvement. The development of custom bioinformatics tools and advanced databases has become an expanding challenge which systematically helps in storing, organizing, manipulating and analyzing large amounts of biological information computationally. In this review, we outline some recent advances in the features of plant genome databases and various platforms with the recent advances in technology.

Abstract

The applications of enzymes are awe inspiring marvels of nature. Scientists can use enzymes to explore all aspects of biology; from molecules to cells to tissues to organs to organism as a whole. For the purpose of food and drinks, enzymes have been exploited by men for thousands of years without really knowing what they are and how do they work? Enzymes have played a pivotal role in many aspects of life since the dawn of life. Today, biocatalysis is being used as a useful alternative to chemical process technology. The fact that enzymes work under much milder conditions oftemperature, pressure and acidity, thus, obviate harsh processing conditions and thereby decrease the possibility of damage to heat labile substrates and save energy. Enzyme technology being eco-friendly can be justifiably termed as‘Green technology’. Due to their high specificity and high catalytic rate, enzymes prevent wastage and reduce time of processing / manufacturing, respectively. The ability of enzymes to act on wide variety of substrates has made them useful tools to exploit cheaper starting material in food industry. Reportedly, over 45% of the enzymes produced are being used in food industry and remaining is shared by detergent (34.4%), textile (11%), leather (2.8%) paper and pulp (1.2%) and other industries (5.6%). Enzymes serve a myriad of functions in food processing, from maximizing juice extraction of pectin-rich fruits to extending shelf-life in baked goods through slowing starch retro-gradation. Indian food processing industry has seen significant growth and changes over the past few years. Though, the market of enzymes is increasing at a fast pace but most of the enzymes of the food sector are coming from overseas. Seeing the unparallel role of enzymes in food processing sector as in multifaceted domains, the researchers should emphasize upon finding novel enzymes and explore their untapped commercial benefits using modern techniques of enzyme engineering, immobilization and biotechnological interventions.

1.    Carbohydrates can be represented by

(a) Fischer projection formula

(b) Haworth cyclic structure

(c) Both (a) and (b)

(d) None of these

2.    If a compound has got four chiral centers then it will have isomeric structures.

(a) 4

(b) 8

(c) 16

(d) 64

3.    The sugar, which does not possess chiral center is

(a) Glucose

(b) Fructose

(c) Glyceraldehyde

(d) Dihydroxyacetone

1.    The basic building block(s) of proteins is/are

(a) Amino acids

(b) Phenolics

(c) Carboxylic acids

(d) Fatty acids

2.    Alpha helix and ?- pleated sheet are characteristic of protein structure?

(a) Primary

(b) Secondary

(c) Tertiary

(d) Quaternary

1.    A lipid is

(a) Insoluble in water but soluble in nonpolar solvents

(b) Insoluble in both water and nonpolar solvents

(b) Soluble in water but insoluble in nonpolar solvents

(d) None of the above

2.    Fats are

(a) Esters of fatty acid with glycerol

(b) Esters of fatty acid with long chain monohydroxy alcohols

(c) Both (a) and (b)

(d) Esters of fatty acid with alcohols

1.    The function of myoglobin is to store in living animal’s muscle.

(a) Oxygen

(b) Nitrogen

(c) CO₂

(d) Oxygen + carbondioxide

2.    Myoglobin is in color when not carrying an oxygen molecule.

(a) Red

(b) Blue

(c) Purple

(d) White

1.    The organic molecules which increase the rate of metabolic reactions are referred as

(a) Coenzymes

(b) Enzymes

(c) Reactants

(d) Apoenzymes

2.    Enzymes are

(a) Organic compounds produced by living organism

(b) Inorganic compounds

(c) Both (a) & (b)

(d) None of these

1.    The predominant form of fat within fat (adipose) tissue is stored in humans in the form of

(a) Glycogen

(b) Triglycerides

(c) Diglycerides

(d) Monoglycerides

2.    The Thermic Effect of food refers to

(a) The ‘heat’ one feels from eating a chili pepper

(b) The amounts of energy the body spents to process, use and store

(c) The benefits of eating warm foods in cold weather

(d) All of the above

1.    Evolutionary relationships between groups of organisms are determined using comparisons of

(a) Biochemical pathways

(b) Nucleotide sequences

(c) Structural features

(d) All of these

2.    The different bacterial species can be subdivided into

(a) Serovarieties

(b) Biovarietites

(c) Subspecies

(d) All of these

3.    Kingdom Prokaryotae include

(a) Bacteria

(b) Protozoa

(c) Fungi

(d) None of these

1.    In milk and milk products, non bacterial ropiness or sliminess may be due to the stringiness/sliminess caused/resulted

(a) Due to thin film formation of proteins, when cooled

(b) From cream thickness

(c) By mastitis, fibrin and leucocytes from the milch animal’s blood

(d) All of the above

2.    In milk, bacterial ropiness is caused by slimy capsular material from the cells usually

(a) Lipids

(b) Proteins

(c) Gums or mucins

(d) Polysaccharides

1.    Yoghurt usually contains total milk solids in the range of

(a) 12-15%

(b) 8.5 to 11.5%

(c) 15-19%

(d) 20-25 %

2.    Yoghurt is usually manufactured by heating the pre-mix to pasteurize it to

(a) 61-62°C for 20 minutes

(b) 80-85°C for 15 to 30 minutes

(c) 80-85°C for 15 sec

(d) 71-72°C for 15 sec

1.    Substantially used metal for manufacture of tin container for heat processed food is

(a) Aluminum

(b) Steel

(c) Iron

(d) Glass

2.    The steel used for the manufacturing of tin free plate metal food cans is

(a) High carbon cold rolled steel

(b) Low carbon hot rolled steel

(c) Low carbon cold rolled steel

(d) Moderate carbon hot rolled steel

3.    Which are the processes primarily used to fabricate the plastic containers used in sterilization process?

(a) Molding and injection

(b) Blowing and injection

(c) Cutting and heating

(d) Conditioing and calendering

1.    Food Additives are

(a) Nutritive substances added to enhance flavour, texture or storage properties

(b) Non-Nutritive substances added to enhance flavour, texture or storage properties

(c) Both (a) and (b)

(d) Chemicals, added for preservation

2.    Which is an acceptable application of a food additive?

(a) As a fat replacer

(b) As an antioxidant

(c) As a food colorant

(d) All of these

1.    Which of the following plastic film is not utilized for metalized flexible packaging?

(a) Polyester

(b) Low-density polyethylene

(c) Bakelite

(d) PVDC

2.    Tin-coating applied to steel base is carried out by

(a) Hot- dipping method

(b) Electrolytic deposition

(c) Cold-dipping method

(d) None of these

1.    The outer layer of cereals is called

(a) Pericarp

(b) Germ

(c) Seed coat

(d) Endosperm

2.    The grain or edible seed of a cereal is known botanically as a

(a) Testa

(b) Caryopsis

(c) Seed coat

(d) Endocarp

1.    Almost all liquid foods are concentrated before drying due to

(a) Technical advantages

(b) Preservation

(c) Nutritional advantages

(d) Both (a) and (c)

2.    Which of the following compound mainly possesses anti-microbial property in garlic and onion?

(a) Acrolein

(b) Eugenol

(c) Allyl isothiocynate

(d) Terpenoid

3.    Which of the following fruit juices concentrates are prone towards spoilage?

(a) Acid

(b) Non-acid

(c) Both (a) and (b)

(d) None of these

1.    Pasteurization can be used to destroy

(a) Soamtic cells

(b) Bacteria

(c) Antibiotics

(d) All of these

2.    The higher amount of total solids in milk will result in

(a) Increased heat stability

(b) Decreased heat stability

(c) Both (a) and (b)

(d) Decreased or increased heat stability depending upon temperature

1.    HACCP was developed by

(a) Pillsbury and NASA

(b) FDA (Food and Drug Administration)

(c) USDA (United States Department of Agriculture)

(d) FSIS (Food Service Inspection Service)

2.    Which is not one of the hazards in HACCP?

(a) Biological

(b) Physical

(c) Bodily

(d) Chemical

3.    Which is not a physical hazard?

(a) Staples

(b) Fingernails

(c) Bandages

(d) Parasites

1.    Mass transfer co-efficient is expressed as

(a) m/s₂

(b) m/s

(c) kg/s

(d) kg/ms

2.    Heat is related to

(a) Flow rate

(b) Energy

(c) Temperature

(d) Momemtum

3.    The units of mass transfer coefficients are

(a) Moles transferred / (time x area x concentration)

(b) Moles transferred / (time x area x mole-fraction)

(c) Moles transferred / (time x area x pressure)

(d) All of the above

1.    Irrotational flow is

(a) Incompressible fluid with shear

(b) Newtonian fluid

(c) Incompressible fluid with no shear

(d) Non-Newtonian fluid

2.    Irrotational flow is also called

(a) Potential flow

(b) Turbulent flow

(c) Laminar Flow

(d) None of these

3.    Bernoulli’s equation is based on the assumption that

(a) The flow is non-viscous, uniform and steady

(b) The flow is steady, non-viscous, incompressible and irrotational

(c) The flow is uniform and incompressible

(d) None of the above

1.    Heat transfer by conduction is given by

(a) Boyle’s law

(b) Stefan’s law

(c) Fourier’s law

(d) Charles’ law

2.    Heat flow per hour is proportional to change in

(a) Area

(b) Vapour pressure

(c) Mass

(d) Temperature

1.    Diffusivity of gases at atmospheric pressure is

(a) < 1 cm²/s

(b) >1 cm²/s

(c) > 10 cm²/s

(d) > 100 cm²/s

2.    Diffusivity of liquids is of the order of

(a) 0.1 cm²/s

(b) 10 cm²/s

(c) 100 cm²/s (d) 1 x 10^-5 cm²/s

1. Size reduction is also referred as

(a) Extraction

(b) Communication

(c) Leaching

(d) Distillation

2. Size reduction causes

(a) Decrease in the temperature of the product

(b) Increase in temperature of the product

(c) Increase in pressure

(d) Decrease in surface area

1.     Which of the following micro-organism is the most heat-resistant in low acid canned foods and its destruction is considered the criteria for successful heat processing?

(a) B.subtilis

(b) C.botulinum

(c) C.sporogenes

(d) B.mycoides

2.    D value represents

(a) Doubling time

(b) Generation time

(c) Decimal reduction time

(d) Decimal reduction temperature

1.     A fruit juice at 20°C with 10% total solids is concentrated in a single effect evaporator that is operated at a vacuum to allow the product moisture to evaporate at 80°C and steam with 82% quality is supplied at 169.06kPa. The desired concentration of the final product is 45% total solids and the concentrated product exits the evaporator at a rate of 300kg/hr. Calculate the steam requirement for the process when condensate is released at 90°C. The specific heat of liquid feed is 4.05 kJ/kg°C and of concentrated product is 3.175 kJ/kg°C.

(a) 3.35 kg/s

(b) 3.25 kg/s

(c) 4.25kg/s

(d) 2.35kg/s

2.     A double effect evaporator is being used to concentrate fruit juice at 35000kg/hr. The juice has 10% total solids at 80°C and requires to be concentrated to 50% total solids. The saturated steam at 1.608 atm is available. What is mass flow rate of water vapors?

(a) 7.505 kg/s

(b) 8.505 kg/s

(c) 5.707kg/s

(d) 6.808.kg/s

1.    Major difference between unleavened and leavened bakery products is

(a) Unleavened do not form cracks on surface

(b) Unleavened do not rise significantly during baking

(c) Leavened bakery products are not attractive

(d) Unleavened products are much more stable

2.    Unleavened bakery products contain small holes throughout the finished product because of

(a) Ingredients contain fats that may swell

(b) Air incorporation between cells

(c) Incomplete coalescence of mixed ingredients

(d) High temperature baking

1.    UV irradiation is considered better than other irradiation methods in terms of

(a) Physical structure maintenance

(b) Chemical structure

(c) Sensory quality

(d) Microbial quality

2.    Irradiation with UV light is considered as

(a) Sterilization method

(b) Disinfection method

(c) Pasteurization method

(d) Cooking method

3.    UV treatment kills bacteria, viruses, fungi due to its effect on

(a) Metabolic pathway

(b) DNA

(c) Signaling pathway

(d) ATP generation

4.    Effectiveness of UV radiation on micro organisms depends on

(a) Species and strain

(b) Spore formation

(c) Culture and growth

(d) Both (a) and (c)

1.1. IMPORTANCE OF FOOD MICROBIOLOGY

Food may be defined as substances that provide nutrients, which when eaten and absorbed by the body, maintain life and growth. Food is basically energy stored in plant and animal foods in chemical form. On consumption, the stored form gets converted to physiological energy. Food is the prime necessity of life. Man has exhibited much thought and foresight in cultivating a variety of grains, fruits, vegetables, nuts and oilseeds and in rearing birds and animals for use as food.

Of the three primary needs of an individual, food, clothing and shelter, ‘food’ occupies the most important place. The biodiversity of foods- cereals, millets, pulses, oilseeds, spices, fruits and vegetables is varied and high in India, where we have varied agro-climatic regions from Kashmir to Kanyakumari. All the fifteen major climates in the world exist in India. India is the second largest producer of food in the world. The impact of green revolution is remarkable in India with many fold increased food production in the last five decades. The full potential of Indian agriculture can not be realized unless India emerges as a major player in the World agriculture.

World population is set to go beyond nine billion by 2050 and demand for food is likely to increase further because of growing affluence and globalization. Food security is achieved when all people have physical and economic access to sufficient, safe and nutritious value added food. India is emerging as a food power in the international trade of foods. The food processing industry in India has been identified as one of thrust areas for the development of the country. It has emerged as a highly perspective sector with immense potential in food processing. The future of Indian food processing industries is bright, provided it improves its quality of products as per international standards.The quality of food processing refers to the adherence of physical, chemical, biological, nutritional and sensory parameters required to achieve the wholesomeness of a food product. Quality control has become an important aspect for food processing industry for both domestic and export markets.

Agricultural food production is increased by adopting scientific farming methods and another way to increase the availability of food is preventing the food spoilage by adopting food preservation methods. The global agricultural and fish production accounts for 50% of perishable food, which requires preservation. Only half of the perishable foods are properly protected. Application of innovative technologies to promote the production of food is indispensable to meet the demand of emerging populations. It is equally important to protect the stored food from the invasion of pests and diseases. A food saved is a food produced.

Food Processing and Preservation, branch of manufacturing that transforms raw animal, vegetable, or marine materials into tasty, nutritious, and safe food products. The industry has its roots in ancient times, as humans have always needed to obtain food and store a portion for later use. Prehistoric humans may have dried fruits in the sun and stored meat in cold areas, such as ice caves. The modern food processing and preservation industry was born in 1809, when French chef and inventor Nicolas Appert, searching for a better way to provide food for Napoleon’s army, devised a method for sterilizing food in tightly sealed glass bottles.

Today a wide variety of methods are available to maintain and enhance the appearance and taste of food. Food processing and preservation methods also create products that are convenient for consumers, such as products that are ready to eat or require minimal preparation and cooking. Combining these methods with modern distribution networks makes seasonal crops available year-round in grocery stores all over the world.

India is emerging as a food power in the international trade of foods. The immense un-tapped potential in the food processing sector in India has to be still exploited. It has been termed as ‘sun rise industry’ for improving agricultural productivity and enhancing food availability. The terms food quality management and food safety have assumed large dimensions today. In the international trade of foods, specifications have been laid down on the levels of harmful substances (chemical or biological origin), protocols have been documented on their detection and quantification in foods. We have to meet these international standards to export processed food and earn foreign exchange. The future of Indian food processing sector is bright provided it improves the quality of its products as per international standards.

Fermentation plays a major role in our diet and give the basic foods like bread, yoghurt, wine and cereal and legume based traditional fermented foods. The development of fermented food products can be considered as one of the greatest achievements of human civilization and goes back thousands of years. It arose from the necessity to conserve foods, to make them more digestible and also more enjoyable. During the centuries, man learned by trial and error to conduct the fermentation processes by changing physical and chemical parameters in the basic food ingredients. It took much longer, however, to discover the cause of fermentation processes: only towards the end of the 19th century it was demonstrated, that baker’s yeast is the cause of alcoholic fermentation. Through the development of the technique of "pure microbial culture", the basis for a controlled use of microbes in food industry was established.

The unique feature of fermented foods is the vital role of microorganisms that bring about essential bio-trasformations of the substrates during fermentation contributing number of desirable properties such as improved product shelf life, enriched diet with improved flavor and texture, increased safety, enriched nutritional supplement and probiotic functions. Fermentation is a chemical reaction carried out by many types of microorganisms to obtain energy. Fermentation is a process for production of a product by means of mass culture of microorganisms. In fermentation, microorganisms breakdown complex organic compounds into simpler substances. Although chemical changes and microbial growth usually mean food spoilage, in some cases fermentation is desirable and microorganisms are actually added to foods. For example, in the production of beer, wine, and other alcoholic beverages, yeasts convert sugar into ethyl alcohol and carbon dioxide. In the making of yogurt and cheese, lactic acid bacteria convert lactose, a sugar found in milk, to lactic acid. Alcohol, acids, and other compounds produced in fermentation act as preservatives, inhibiting further microbial growth. In addition to its use with alcoholic beverages, cheese, and yoghurt, fermentation is used to produce yeast bread, soy sauce, cucumber pickles, sauerkraut, and other traditional fermented food products. The variation in agroclimatic conditions prevailing in India and diverse form of dietary culture of various ethnical groups produced traditional fermented foods such as idli, dosa (rice-legume based), vada, papad, wari, balle (legume based), bhatura, jelabi, nan (wheat based), paneer, shrikhand (milk based).

Milk is nutritious and essential food for human beings and also serve as good medium for microbial growth and contamination. Milk is a single, most nearly complete, natural food. Primarily it is meant for nourishing the newborns but man has exploited it for human consumption since long. Today milk has become indispensable integral component of our diet. About half the milk produced is consumed as fresh milk, the rest going into a variety of products including evaporated and condensed milk, dried milk powder, butter, cheese, malted milk, ice cream, yoghurt, lactose and casein. Milk is very important from a nutritional standpoint since it contained all the essential food constituents (carbohydrate-lactose, protein-casein, fat-butter, minerals- calcium, potassium and vitamins- A, B, C, D, E, and K) required in human diet in about the proper proportions. India is the second largest producer of milk in the world. India has exhibited unprecedented rate of growth in dairy development in last 30 years mainly due to sustained efforts of dairy technologists in Operation flood Programme introduced by the National Dairy Development Board. Dairy microbiology deals with aspects like shelf life and spoilage microbes, public health significance and food borne pathogens, and production of fermented dairy products.

SINGLE CELL PROTEIN (SCP) AND PROTEIN DEFICIENCY

Protein is an essential component of diet. The greatest single problem in the world today is global food protein shortage. Having adequate quantity of food is only one side of the picture, but the most important aspect is the supply of balanced and nutritious food. All efforts are being made to increase the food production through modern methods of farming. But very little attention is being paid towards protein requirements and production. Approximately half of world population suffers from the protein deficiency disease called ‘Kwashiorkor’ and children with poor protein are victims of this disease.

Usually, cereals have low protein values while protein rich pulses are not available in desired quantities due to poor yields and high costs. The good quality protein available in fish, meat, poultry, and eggs is not available due to poor economic condition as well as varied dietary habits. With the current system of production, agriculture cannot be relied upon to feed an ever increasing world population. Hence there is an urgent need to find other protein sources. The best potential is seen in microbial protein or single cell protein (SCP), a new source of protein independent of agriculture.

DEFINITION: The dried cells of microorganisms such as bacteria, fungi, yeasts, algae that are grown in large scale culture systems as proteins for human or animal consumption are collectively known as "single cell proteins".

Mushrooms are most ancient, best known and greatly admired fleshy macrofungi. Mushrooms are delicacies, much sought after and greatly valued foods. Wild mushrooms are mostly found in forests, tree trunks, pastures, lawns and road side during winter season and appear at surprising speed. Mushroom hunting or gathering is a popular hobby in Western countries. The wild mushrooms may be edible or unpalatable or poisonous. Poisoning by wild mushrooms is common and may be fatal or produce merely mild gastrointestinal disturbance or slight allergic reaction. The term toad stool is popularly reserved for inedible or poisonous mushrooms, but this classification has no scientific basis. This alarming term keeps many people away from these foods. It is important that every mushroom intended for eating be accurately identified. Mushrooms vary in colour, size, shape, growth habit, yielding ability and other characteristics.

STRUCTURE: Mushrooms are the fleshy fungi which constitute a major group of lower plant kingdom. Mushroom is the conspicuous umbrella-shaped fruiting body (sporophore) of certain fungi of the order Agaricales in the class Basidiomycetes but also of some other groups. Popularly, the term mushroom is used to identify the edible sporophores. The edible reproductive part consists of a stem and a cap. Gills found on the underside of the cap, are arranged like spokes in a wheel. The gills bear multiple spores which start new fungi. The sporophore emerges from an extensive underground network of fine thread like white growth known as mycelium. The mushroom, fruit body produced basidiospores at the tip of club like structures, called basidia, which are arranged along the gills of the mushroom. Beneath the mushroom, in the soil, is the mold colony itself, consisting of a mat of intercoiled hyphae, sometimes several feet in diameter. The mushrooms first appear as white tiny ball consisting of short stem (stipe) and a cap (pileus) which begins to open up like an umbrella. The delicate membrane or Veil (velum) enveloping the cap tears off, if allowed to develop fully, and lamellae (gills) radiating from the stalk into the cap become visible. These gills become darkened as the basidiospores (seeds) develop into millions and fall in the ground for starting their life cycle once again for second generation of mushrooms.

Several attempts have been made to detect the biopotentials of microorganisms with reference to their ability to produce various enzymes with a view to use them in industrial processes and bioremediation applications. Enzymes are increasingly used as a new route to synthesize food ingredients such as flavours, emulsifiers, sweeteners, food additives, nutrients. With the advent of genetic engineering, a wide range of enzymes has become available on a large scale and this has increased the scope of enzyme technology.

MICROBIAL ENZYMES: Enzymes are proteinaceous complex organic catalysts of biological origin and vital constituents of cells. Microbes produce a variety of enzymes, intracellular and extracellular enzymes. Most of the microbial enzymes produced for commercial usage are extra cellular enzymes. Extracellular enzymes are secreted outside the cell and hydrolyze polymeric substances. Amylases and proteases are enzymes of economic importance. At present over 60 enzymes are in commercial use, of which three-quarters are hydrolytic enzymes. Commercial production of microbial enzymes utilizes a variety of fungi, yeasts and bacteria. The composition of the medium, genetic stability of the microbial strain and physical and chemical factors of fermentation influence the production of a particular enzyme.

Enzymes catalyze a variety of reactions during processing and preservation of food products and form a large group of processing aids. Food industry utilizes enzymes in the production of bakery items, dairy products, fruits and vegetables juices and products, tenderization of meat, modification of oils and fats, flavour production and preservation of food products. Enzymes have also found use in the manufacture of ingredients like glucose, high fructose syrup, citric acid, colour and flavour constituents.

Microbial contamination sources: Foods may be contaminated by microorganisms at any time during harvest, storage, processing, distribution, handling, or preparation. The primary sources of microbial contamination are soil, air, animal feed, animal hides and intestines, plant surfaces, sewage, and food processing machinery or utensils. Since most foods either carry or eventually acquire bacteria, molds, or yeasts, microorganisms are the major causes of food spoilage. The increased load of microorganisms leads to rapid spoilage.

Organisms: Bacteria and fungi (yeasts and molds) are the principal types of microorganisms that cause food spoilage and food- borne illnesses. The typical microorganisms that cause food spoilage are bacteria (e.g., Pseudomonas), yeasts (e.g., Candida), and molds (e.g., Rhizopus). The growth of microorganisms in the food will increase the load of microorganisms, and the heavier load will add to the difficulty of preventing spoilage and may influence the kind of spoilage to be anticipated.

Food spoilage may be defined as any change that renders food unfit for human consumption. These changes may be caused by various factors, including contamination by microorganisms, infestation by insects, or degradation by endogenous enzymes (those present naturally in the food). In addition, physical and chemical changes, such as the tearing of plant or animal tissues or the oxidation of certain constituents of food, may promote food spoilage. Foods obtained from plant or animal sources begin to spoil soon after harvest or slaughter. The enzymes contained in the cells of plant and animal tissues may be released as a result of any mechanical damage inflicted during postharvest handling. These enzymes begin to break down the cellular material. The chemical reactions catalyzed by the enzymes result in the degradation of food quality, such as the development of off- flavours, the deterioration of texture, and the loss of nutrients. The enzymatic changes in foods are desirable to some extent as in the case of ripening of fruits, but continued enzymatic activity beyond an optimum point becomes food deterioration due to rotting. The native enzymes may be inactivated by heat, radiation or by the use of specific chemicals.

10.1 CEREALS AND CEREAL PRODUCTS

CONTAMINATION: The sources of contamination in cereals and cereal products are soil, insects, air, etc. Most of the microorganisms are removed with the outer portions of the grain during milling. The bleaching agents used during milling also reduce numbers of microorganisms. The bacteria in wheat flour include Bacillus, Micrococcus, Flavobacterium. Mold spores are chiefly of Aspergillus spp and Penicillium spp and in addition Alternaria, Cladosporium and other genera are found. The numbers of microbes in cereals and cereal products vary widely from few hundred per gram to million. Corn meal contains several hundred to several thousand bacteria and mold per gram.

11.1. FRUITS-Maturation, Ripening and Storage

Fruits are natural foods containing substantial quantities of essential nutrients and the best sources of minerals like sodium, potassium and magnesium, vitamins (antioxidants), such as vitamin A, C and enzymes. They are rich in fructose and water. Fruits are living biological entities that perform a number of metabolic functions. Two functions of particular importance in fruit processing are respiration (the breaking down of carbohydrates, giving off carbon dioxide and heat) and transpiration (the giving off of moisture). Senescence is the period when chemical synthesizing pathways give way to degradative processes, leading to aging and death of tissue. Fruit ripening is thus the result of many complex changes, some interactive but many independent of one another. Once the fruit is harvested, respiration and transpiration continue, but only for as long as the fruit can draw on its own food reserves and moisture. It is this limited ability to continue vital metabolic functions that defines fruit as perishable.

CONTAMINATION

The healthy inner flesh of meat contains few or no microorganisms, although they have been found in lymph nodes, bone marrow and intestine. Staphylococcus, Streptococcus, Clostridium and Salmonella have been isolated from lymph nodes of red meat animals. During slaughtering the lymph nodes are removed from edible parts. The important contamination, however comes from external sources during bleeding, handling and processing. During bleeding, skinning and cutting the main sources of microorganisms are from the exterior of the animal- hide, hoof and hair and the intestinal tract. The exterior of the animal harbours large number and many kinds of microorganisms from soil, water, feed and manure as well as its natural surface flora.

Knives, cloths, air and hands and clothing of workers can serve as intermediate sources of contamination. During handling and processing the contamination can come from containers, air, other contaminated meat, equipments and personnel.

Molds that grow on the surface of the meat include the species of Cladosporium, Sporotrichum, Geotrichum, Mucor, Monilia, Penicillium and Alternaria. The important bacteria found in meat are Staphylococcus, Sarcina, Streptococcus, Clostridium, Leuconostoc, Lactobacillus, Proteus, Flavobacterium, Bacillus, Streptomyces, Escherichia and Salmonella.

13.1. CONTAMINATION

MICROFLORA: The flora of living fish depends upon the microbial contents of the waters in which they live. The slime in the outer surface of the fish contain bacteria of the genera: Pseudomonas, Alcaligenes, Micrococcus, Flavobacterium, Corynebacetrium, Bacillus, Sarcina, Serratia and Vibrio. The same species of bacteria are found in shrimps, crabs, lobsters and similar sea foods. Oysters and Shell fish that pass large amount of water through their bodies, pick-up soil and water microorganisms in this way including human pathogens. Common spoilage microorganisms of fish include species of Pseudomonas, Moraxella, and Acinetobacter, found mainly in marine fish, and Bacillus and Micrococcus, found in freshwater fish. Fish may also contain pathogenic (disease-causing) microorganisms such as Salmonella and Escherichia coli. Pathogenic contamination is of special concern with mollusks because they are often eaten raw and as whole animals.

SOURCES: Boats, boxes, bins, fish houses and fishermen are the sources of contamination of these bacteria. The bacterial population ranges from few hundred to few million per square centimeter. Because of their soft tissues and aquatic environment, fish are extremely susceptible to microbial contamination. At the time of harvest, fish carry a high microbial load on the surface of their skin, in their intestinal tract, and in their gills. The type and number of microorganisms that live in fish vary according to the season, the species, and the natural habitat. Additional contamination may occur during the harvesting, handling, or processing of the fish. Harvested fish must be immediately stored in a low-temperature environment such as ice or refrigerated seawater. This chilling process slows the growth of microorganisms that live in fish and inhibits the activity of enzymes. Because fish have a lower body temperature, softer texture, and less connective tissue than land animals, they are much more susceptible to microbial contamination and structural degradation. If immediate chilling is not possible, then the fish must generally be sold and eaten on the day of the harvest.

14.1. EGGS

India is the third largest producer of eggs. Fresh eggs are gathered on automatic collection belts at the farm and stored in a cooler at about 7°C. The eggs are then delivered to a central processing plant, where they are washed, sanitized, and graded. Grading involves the sorting of eggs into size and quality categories using automated machines. Flash candling (passing the eggs over a strong light source) detects any abnormalities such as cracked eggs and eggs containing bloodspots or other defects. Higher-grade eggs have a thick, upstanding white, an oval yolk, and a clean, smooth, unbroken shell.

14.1.1. Eggs Contamination

More than 90 percent of all eggs are free of contamination at the time they are laid; contamination with Salmonella bacteria and with certain spoilage organisms occurs essentially afterward. They become contaminated by faecal matter from the hen, by the lining of nest, by handling, by wash water and packing materials. The total number of microorganisms per shell of a hen’s egg was found to range from 100 to 10,000,000 with a mean of about 100,000. Proper washing and sanitizing of eggs eliminates most Salmonella and spoilage organisms deposited on the shell. The organism Salmonella enteritidis, a common cause of gastroenteritis (a form of food poisoning), has been found to be transferred through the hen ovary in fewer than 1 percent of all eggs produced. Ovarian- transferred S. enteritidis can be controlled by thorough cooking of eggs (i.e., until there are no runny whites or yolk).