fOOD MICROBIOLOGY
BIOGEOCYCLES, BIOFERTILIZER
6. Food Microbiology : Introduction Food is a basic requirement of man than even shelter and cloth- ing. It is the source of nutrients and provides the energy required for all activities of a human body, such as growth, repair of the damaged tis- sues, reproduction and sustenance. So the food should be free from microorganisms. The first person to appreciate and understand the pres- ence and role of microorganisms in food was Pasteur. In 1837, he showed that souring of milk was caused by microorganisms and also he used the heat for the first time to destroy undesirable organisms in milk, wine and beer.
This process is well known now as pasteurization. Food is an indispensable substrate for all living organisms. All food items are associated with microorganisms in one form or other. Some of the naturally occurring foods such as fruits and vegetables contain number of microorganisms. Foods get contaminated during handling, harvest, transport and storage. Food forms ideal culture medium for the growth of the microorganisms. The study of microorganisms asso- ciated with food, food poisoning and their role in the welfare of human beings both in harmful and useful ways form the subject of food micro- biology.
6.1. Food preservation Food preservation is a technique to prevent spoilage, food infection, food poisoning and microbial contamination from the food.
Food preservation is done with following aspects: a) to prevent and to remove microbial contamination and also to inhibit microbial growth and metabolism. (b) to kill the contaminating pathogens and to mini- mize food spoilage and food poison
6.1.1.Principles and methods of food preservation The basic principle of food preservation primarily involves the process of inhibiting i) the growth and activity of microorganisms
ii) the activity of endogenous enzymes
iii) the chemical reactions which may determinate quality of food and
iv) invasion and spoilage by insects and rodents.
In addition, spoilage of food may be caused during mechanical handling, processing, packaging, storing and transportation. Appro- priate care has to be taken to prevent deterioration of quality of food. Several methods are available for preservation of food based on the above principles. The methods include 1) preventing the accessibility of food to microorganisms by asepsis packaging, 2) physical removal of microorganisms from food by filtration or centrifugation,
3) hindering the growth and metabolic activity of microorganisms by use of preser- vatives, use of low temperature and decreasing water activity in foods by drying 4) killing of the microorganisms by use of high temperature and ionizing radiations, 5) inactivation of endogenous enzymes by mod- erate heating,
6) inhibition of chemical reactions through the use of chemi- cal additives, 7) fermentation of foods to yield more stable or less per- ishable food products. Food preservation as it is practiced in the industry always in- volves the use of combination of methods for achieving maximum ef- fectiveness. Asepsis or preventing the accessibility of food to microorgan- isms is well exemplified in nature. The protective covering on natural foods such as skins on fruits and vegetables, shells on eggs and nuts and skins and membranes on livestock and fish prevent the attack by microorganisms and maintaining the living tissues in healthy condition. Filtration or centrifugation is adopted to physically remove microor- ganisms particularly in liquid foods such as milk, soft drinks, fruit juices and alcoholic beverages.
BIOGEOCYCLES, BIOFERTILIZER
6. Food Microbiology : Introduction Food is a basic requirement of man than even shelter and cloth- ing. It is the source of nutrients and provides the energy required for all activities of a human body, such as growth, repair of the damaged tis- sues, reproduction and sustenance. So the food should be free from microorganisms. The first person to appreciate and understand the pres- ence and role of microorganisms in food was Pasteur. In 1837, he showed that souring of milk was caused by microorganisms and also he used the heat for the first time to destroy undesirable organisms in milk, wine and beer.
This process is well known now as pasteurization. Food is an indispensable substrate for all living organisms. All food items are associated with microorganisms in one form or other. Some of the naturally occurring foods such as fruits and vegetables contain number of microorganisms. Foods get contaminated during handling, harvest, transport and storage. Food forms ideal culture medium for the growth of the microorganisms. The study of microorganisms asso- ciated with food, food poisoning and their role in the welfare of human beings both in harmful and useful ways form the subject of food micro- biology.
6.1. Food preservation Food preservation is a technique to prevent spoilage, food infection, food poisoning and microbial contamination from the food.
Food preservation is done with following aspects: a) to prevent and to remove microbial contamination and also to inhibit microbial growth and metabolism. (b) to kill the contaminating pathogens and to mini- mize food spoilage and food poison
6.1.1.Principles and methods of food preservation The basic principle of food preservation primarily involves the process of inhibiting i) the growth and activity of microorganisms
ii) the activity of endogenous enzymes
iii) the chemical reactions which may determinate quality of food and
iv) invasion and spoilage by insects and rodents.
In addition, spoilage of food may be caused during mechanical handling, processing, packaging, storing and transportation. Appro- priate care has to be taken to prevent deterioration of quality of food. Several methods are available for preservation of food based on the above principles. The methods include 1) preventing the accessibility of food to microorganisms by asepsis packaging, 2) physical removal of microorganisms from food by filtration or centrifugation,
3) hindering the growth and metabolic activity of microorganisms by use of preser- vatives, use of low temperature and decreasing water activity in foods by drying 4) killing of the microorganisms by use of high temperature and ionizing radiations, 5) inactivation of endogenous enzymes by mod- erate heating,
6) inhibition of chemical reactions through the use of chemi- cal additives, 7) fermentation of foods to yield more stable or less per- ishable food products. Food preservation as it is practiced in the industry always in- volves the use of combination of methods for achieving maximum ef- fectiveness. Asepsis or preventing the accessibility of food to microorgan- isms is well exemplified in nature. The protective covering on natural foods such as skins on fruits and vegetables, shells on eggs and nuts and skins and membranes on livestock and fish prevent the attack by microorganisms and maintaining the living tissues in healthy condition. Filtration or centrifugation is adopted to physically remove microor- ganisms particularly in liquid foods such as milk, soft drinks, fruit juices and alcoholic beverages.
No comments:
Post a Comment