Unknowingly, man has made use of microorganisms since the seventeenth century, mostly in the production of food and drinks such as leavening of bread, souring of milk and making of beer and wine.

Microbiologists study and investigate microorganisms and their relationship with man, animals and plants. Some of the sub-categories of microbiologists include the following: (i) Food microbiologists focus on food pathogens and food spoilage organisms as well as microorganisms in food production, i.e. fermented foods. (ii) Industrial microbiologist work with industries producing products such as alcoholic beverages, amino acids, citric acids, vitamin C and antibiotics. (iii) General microbiologists focus on the fundamental and basic features of microorganisms' ecology, metabolism, genetics, physiology, morphology and anatomy. (iv) Agricultural microbiologists study plant diseases, the role of microorganisms in soil fertility and spoilage of farm products. (v) Medical microbiologists study the role of microorganisms in inflicting diseases in humans and animals. They research and investigate these organisms to find ways to cure and prevent the occurrence of diseases. (vi) Marine microbiologists deal with microorganisms present in the ocean. This is a relatively new area of microbiology.

Throughout the world, food production and hence the role of the microbiologist has become more complex. Raw materials are frequently sourced globally and food is processed through an increasing variety of techniques. Therefore approaches to safe food production are being assessed on an expanding platform from national, European, transatlantic and beyond.

The role of the food microbiologist in addition to keeping abreast of new technological changes in production methods and in methods of microbiological analysis involves: (i) To monitor the effect of processing changes (pH, temperature, etc.) on microbial load. (ii) To determine the dominant foodborne microorganisms in different types of food. (iii) To detect different microorganisms using reliable and consistent methods. (iv) To establish reliable and consistent microbiological criteria as a numerical means of interpreting end-product testing. Microbiological criteria are implemented by microbiologists in food processing plants based on total counts, or numbers of certain indicator organisms or presence or absence of certain pathogens. The main concern with indicator organisms is what kind of indicator should be considered meaningful in a particular food and in what numbers? The relationship of an indicator to a pathogen is not well defined under all conditions. This makes the role of microbiologist very challenging. (v) Use predictive microbiology as a research tool to understand the consequences of processing changes. (vi) To implement and improve the role of Hazard Analysis Critical Control Point in food processing. (vii) To implement the objectives of microbial risks assessment. (viii) To implement food safety objectives in food processing.

Food microbiologists strive to achieve the following: (i) Food that is safe and does not pose a public health risk. (ii) The food products are made of ingredients and materials that are high quality and have not undergone deterioration or contamination during processing, packaging, storing, shipping and marketing. (iii) The food will have the keeping quality that can be reasonably expected of that product.

Microbial quality and safety of foods are some of the primary concerns of food

(i) Food procurement. The wholesomeness and safe source of food are basic to the protection of the consumer from a public health point of view, particularly of food considered potentially hazardous. A potentially hazardous food may be defined as any food that consists in whole or in part of milk or milk products, eggs, poultry, fish, shellfish, crustacean or other ingredients including synthetic ingredients in a form capable of supporting rapid and progressive growth of infectious or toxigenic microorganisms. This definition does not apply to foods with a pH of 4.6 or a water activity value of 0.85 or less. (ii) Food storage. Storage facilities should be kept in excellent repair and immaculately clean. Dry storage rooms should be at a temperature of 10-21 ºC and well ventilated. A relative humidity of 50-60% is satisfactory. Frozen foods should be stored at a temperature of -18 ºC or below in order to maintain the culinary quality. Chilled foods should be stored at a temperature of 2-4 ºC, meat and poultry at a temperature of -1-2 ºC, fish at a temperature of -1 ºC and fruits and vegetables at a temperature of 1.7-7.2 ºC. (iii) Food packaging. Proper packaging protects food from contamination and unwanted changes in texture and facilitates handling and storage. (iv) Preprocessing. This stage occurs before the processing of food items. Cross-contamination from raw to processed items is a danger that must be eliminated by all control methods. (v) Heat processing. This is a production activity designed to destroy and to kill most if not all pathogenic organisms. The Food Service Sanitation Manual of the United States Food and Drugs Administration states that potentially hazardous food requiring cooking shall be cooked to heat all parts of the food to a temperature of at least 60 ºC. (vi) Food storage following heat processing. In conventional systems food storage may be hot hold, chilled storage or freezer storage. (vii) Heat processing of precooked menu items. Precooked food items that are chilled or frozen, should be heated fast to an internal temperature of 74 ºC. This rapid heating would serve to significantly reduce Clostridia and Staphylococci. (viii) Food product distribution. Food prepared at their place of manufacture must be properly transported at the right temperature to places of services which may be quite distant. Chilled foods should be maintained at 7.2 ºC or below. Hot foods should be maintained at 60 ºC or above. Frozen food should be maintained at -18 ºC or below. (ix) Food service. At the food service centre, contamination and temperature must be carefully monitored.

Food microbiologists have several areas of concern that require further research. (i) Investigating the effects of alternate methods of food procurement, storage, preparation and service upon the microbial, nutritional and sensory quality of selected menu items in foodservice operations. (ii) Determining the effects of innovative materials handling techniques in each type of foodservice system upon the growth and survival of pathogenic microorganisms of public health significance. (iii) Formulating procedures to be used as managerial tools for decision making about preparing and serving quality menu items within the foodservice system. (iv) Identifying factors within the physical environment of the foodservice system that directly affect food quality and safety and correlate the effect of the relationships among these influential factors with food quality. (v) Determining methods through which the systematic control of food quality and safety can be achieved by automated and computerized methods.

References • Health People 2000 Status Report Food Safety Objectives, 2000. • Longree, K. Quantity Food Sanitation. John Wiley & Sons, 1980. • Pattron, D.D. Food
About the Author

Dr Pattron is a Public Health Scientist in the Ministry of Health, Trinidad.