Fish products and Byproducts Technology

Unit 1 - Principles of Fish Preservation

1.5.6. Marinating
The marinades are preserved by keeping them in acid medium (acetic acid and propionic acid) containing salt at a pH 4.5. At a pH 4.5 or below most of the spoilage causing and all food poisoning bacterial growth is arrested, resulting in a product with a characteristic flavor and an extended but limited shelf life. Acetic acid controls the pH and selectively allows the autolytic reactions to take place. The salt (sodium chloride) causes the removal of water and coagulates the protein. It also controls the hydrolytic action and allows it to proceed within desired limits. However some bacteria and enzymes will remain active and cause spoilage, which can be slow down by storing at low temperatures (below 10^oC). The amounts of acid and salt required can be reduced when the product is kept chilled until eaten.