Food spoilage, food infections and intoxications caused by microorganisms and methods for their detection Dr. Neeraj Dilbaghi Reader, Department of Bio & Nano Technology Guru Jambheshwar University of Science and Technology Hisar- 125001 and
Dr (Mrs.) S. Sharma
Professor, Department of Microbiology, CCS Haryana Agricultural University, Hisar- 125001 (Revised 25-Sep-2007) CONTENTS Introduction Food Spoilage and General Principles Underlying Spoilage of Food Intrinsic Parameters Extrinsic Parameters Microbial Spoilage of Foods Spoilage of fresh and ready-to-eat meat products Spoilage of milk and milk products Spoilage of fruits and vegetables Spoilage of canned foods Major Food Borne Infections/ Intoxications Caused by Bacteria General Control Measures for Prevention of Food Borne Diseases Microbial Testing of Foods Conventional Methods Rapid Detection of Emerging High Risk Pathogens in Foods
Food spoilage, microbial food spoilage, Food borne infections; Food testing; Food borne diseases
Introduction Foods and microorganisms have long and interesting associations which developed long before the beginning of recorded history. Foods are not only nutritious to consumers, but are also excellent source of nutrients for microbial growth. Depending upon the microorganisms present, foods may spoil or preserved by fermentation. Microorganisms can be used to transform raw foods into fermented delights, including yoghurt, cheese, sausages, tempeh, pickles, wine, beers and other alcoholic products. On the other hand, foods also can act as a reservoir for disease transmission, and thus detection and control of pathogens and spoilage organisms are important areas of food microbiology. During the entire sequence of food handling from the producer to the final consumer, microorganisms can affect food quality and human health. History of microorganisms in food There is no documentation to exactly pinpoint as to when man first became aware of the presence of microorganisms in food. The year 1674 marks the birth year of microbiology when Leeuwenhoek first examined microorganisms in a sample of lake water. It was after about 100 years when Microbiology was established as science. Several experiments conducted by scientists to explain the origin of microorganisms provided indirect evidence of association of microorganisms in food. The period prior to establishment of Microbiology/ Bacteriology as science is designated as prescientific era which includes a food gathering period and food producing period. Food gathering period covers time of man's origin about 3 million years up to 8000-10000 years ago. In this period man was carnivorous and plant foods entered his diet later. Man also learnt to cook food during this period also. Food producing period ranges from 8000- 10000 years ago and includes present time. Many problems related to prepared foods were encountered during this period for example the problem of food spoilage due to improper storage and problem of food poisoning with prepared foods as well as problem of disease transmission by foods. Although scientific basis for the preservation of foods were not known at that time but some of the methods used for preservation were use of oils, snow, smoking of meats, etc. Perhaps the first man to suggest role of microorganisms in food spoilage was a Monk Kircher who referred to worms in decaying bodies, spoiled milk etc. The observations by Spallanzani that heated meat infusion in a hermetically sealed flask remained unspoiled and free from microorganisms and experiments by Pasteur while disproving the spontaneous generation theory demonstrated the idea of food preservation by heat. The spoilage of food and presence of food poisoning organisms in food are very important from the point of food safety. Today the emphasis is on total quality of food which means that not only food should be nutritionally balanced but should be microbiologically...