Effects of Extrusion Cooking on Food Quality Attributes, Storage Stability, and Inactivation of Bacterial Spores: A Review

The objective of this study was to review the literature on the definition and components of food quality, examine the storage stability of foods and evaluate the effect of extrusion cooking on contaminating microorganisms. Food quality encompasses the attributes that determine consumer acceptability, with consumers serving as the primary arbiters of quality. These attributes may be extrinsic (e.g., colour) or intrinsic (e.g., chemical composition). Food quality is typically monitored through standardized quality control tests assessing multiple parameters and is often enhanced through legislative frameworks that render non-compliance subject to legal sanctions. A major challenge for food processors is ensuring product stability during storage. Storage stability assessments are conducted to evaluate changes in product quality over time and appropriate packaging plays a critical role in enhancing stability and extending shelf life. Microorganisms pose significant challenges by causing food spoilage and foodborne illnesses. Raw materials may be exposed to various sources of contamination prior to extrusion cooking and inadequate hygienic practices may also render the extruder itself a source of contamination. Extrusion cooking contributes to microbial inactivation through the combined effects of high temperature, moisture content and mechanical shear within the screw, which can destroy microbial cells, enzymes, spores and toxins. Since food spoilage is predominantly of microbial origin, food processing primarily aims at preservation to prolong shelf life. Additionally, reduced water activity inhibits the growth of many microorganisms, particularly bacteria, thereby further contributing to product stability.