**2. Food spoilage**

By definition, food spoilage is the process that renders food unfit for human consumption [4]. Various factors, such as contamination by microorganisms, insect infestation, or enzyme degradation, cause food spoilage [5]. In addition, physical changes, such as tearing plant or animal tissues, and chemical changes, such as oxidation of certain constituents of food, cause food spoilage. Foods from plant or animal sources degrade after harvest and slaughter due to enzymes in the plant cells and animal tissues and mechanical damage caused during harvesting and post-harvest handling. The enzymes in the foods break down due to chemical reactions catalyzed due to the storage environment causing food spoilage or degradation—the changes or degradation results in off-flavors, textural changes, and loss of nutrients [6]. The common food spoilage bacteria are *Lactobacillus*, yeasts, *Saccharomyces*, and molds (e.g., *Rhizopus*). In addition, bacteria and fungi (yeasts and molds) cause food spoilage and foodborne illnesses. In addition, microorganisms may contaminate foods during harvest, storage, processing, distribution, handling, or preparation. Enzymes that cause the degradation of the food quality are listed in **Table 1** [7].


#### **Table 1.**

*Enzymes involved in the degradation of food quality.*
