The course aims to provide basic knowledge on the microorganisms involved in the processing, preservation and spoilage of foods of animal and plant origin; their activities will be described with particular reference to the interactions between microorganism-product and microorganism-process. The aspects of safety and traceability of food will be studied through the application of innovative methodological approaches that enable the rapid and specific detection of biotic components both undesired and potentially dangerous to the consumer health.
The aim of this laboratory teaching is to show to the students a protocol for the analysis of a food using classical and molecular analytical methods.
Introduction to food microbiology. Foods as growth substrate for microorganisms. Ecology of food contamination. Microbial behaviour as a function of the micro-ecological features of the food. Intrinsic and extrinsic parameters that affect microbial growth in food (pH, water activity, temperature, humidity, nutrients, ect.). Physical and chemical methods to reduce microbial growth in food. Food preservation by using additives, radiations, low and high temperatures, lyophilisation, fermentation processes. Incidence, type and characteristics of microorganisms associated with food.
Pro-technological microorganisms, spoilage microorganisms and pathogens.
Characterization and metabolism of the main microbial groups of interest in food: lactic acid bacteria, yeasts and moulds.
Microbiological aspects related to non-fermented foods of animal origin (milk, meat, processed meat, fish, eggs) and vegetable origin (fresh vegetables, minimally processed vegetables, fruits, seeds, flour, pasta).
Importance of the fermentation processes in food processing. Microbiological aspects related to fermented foods of animal origin (sausages and cured meats) and of plant origin (wines and special wines, beer, bread and sourdough bread, vinegar and balsamic vinegar, olives, sauerkraut).
Definitions of biological safety, traceability, risk ... Safety issues (biotic components unwanted and potentially dangerous to health, and compounds released by microorganisms, eg. mycotoxins, biogenic amines, AR genes).
Food-borne microorganisms of interest for safety: Aeromonas hydrophila, Clostridium botulinum, Salmonella, etc..
Molecular methods specific for the detection of pathogens and of undesirable compounds released / present in the food.
National and international legislation related to the food safety.
Solutions, such as detection of the contamination points in the food chain, prevention, application of methods for detecting the contamination in food production.
Different probiotic fermented dairy foods, commercially available, will be microbiologically analyzed by plating serial dilutions on selective media. The colonies will be classified based upon their morphology and cells will be observed at the optical microscopy. Some representative colonies, picked up from growth plates, will be analyzed genetically by determining the molecular fingerprinting obtained with the RAPD-PCR technique. In the last session of laboratory teaching, experimental data of each fermented food will be compared to each other and discussed.