Fish Microbiology and Quality Assurance

Unit 9 - Assurance and management quality of fish

9.1.4. Microbiological methods
Microbiological methods assess the quality of the product by enumerating the total numbers of microorganisms, or presence or absence of specific microorganisms as indicators of quality in a fixed quantity of product. These methods involve growing microorganisms in specific nutrient agar media or in special media that support only particular microorganisms. The total number of living bacteria present in a food is variously reported as the total viable count (TVC), standard plate count (SPC), surface total plate count (TPC), aerobic plate count (APC) or as colony forming units (CFU).

Significance of microbial load in foods
The total microbial load provides an estimate of the total number of aerobic organisms in a particular food. The microbial load of products reflects on;

• Microbiological quality of the food.
• Potential indicator of spoilage of the perishable food products.
• Indicator of the sanitary conditions under which the food was produced and / or processed
• Indicator of level of Good Manufacturing Practices (GMP) adopted during processing.
• Generally, TPC values of 107/g is an indicative of fish being spoiled.

Microbes to be enumerated
Microbiological investigations generally involve enumerationg total microbial load responsible for spoilage, human pathogenic microorganisms such as V. cholerae, V. parahaemolyticus, Salmonella sp, Listeria etc, indicators of sewage contamination such as faecal coliforms, E. Coli, faecal streptococci, and indicators of personnel hygiene such as Staphylococcus aureus in fresh and processed products by employing appropriate standard enumeration methods. Microbiological methods are generally laborious but are required for monitoring sanitary practices and levels of hygiene in fish processing plants.