Fish Microbiology and Quality Assurance (2+2)

Unit 2 - Growth and survival of microorganisms in food

2.1. Factors affecting the growth of microorganisms in fish

Foods meant for human consumption are rarely sterile, and contain several microorganisms. Microorganisms associated with food include natural micro-flora of raw material and organisms that are introduced during harvesting / handling, processing, storage and distribution.

The microbial load in food depends on factors such as

• Nature of the food
• Storage environment
• Properties of organisms in foods
• Effects of processing

Generally, micro-flora associated with food has no effect and food is consumed without objection and no adverse consequences. But in some instances associated microorganisms manifest their presence leading to spoilage, food borne illness or Transformation of properties of food in a beneficial way (Ex. Fermentation).

Factors affecting microbial growth in foods
Microorganisms associated with food and their growth is affected by several factors. These are broadly grouped into 2 types.

1. Intrinsic factors :Includes physicochemical properties of food such as,

• Nutrients
• pH and buffering capacity
• Redox potential
• Water activity / moisture content
• Antimicrobial constituents

2. Extrinsic factors:Include conditions of storage environment such as,

• Relative avidity
• Temperature of storage
• Gaseous atmosphere
• Presence / activities of other organisms