In fermented foods, the presence of BAs is due to the decarboxylase activity of the lactic acid bacteria (LAB) used as starter culture, and to the action of some spoilage bacteria. In non-fermented foods, the presence of BAs is only indicative of undesired microbial activity. Therefore, the amine level could be used as an indicator of microbial spoilage. The amounts of histamine, putrescine, and cadaverine usually increase during spoilage of fish and meat. Early detection of BA- producing bacteria is essential in the food industry, in order to avoid the risk of amine formation and, subsequently, a cause of food-borne disease. Several methods exist for isolation, identifying, and determination of biogenic amines in fermented foods.

Orange juice concentrate is one of the most important orange products, which is widely appreciated in the world market. Concentration of orange juice by evaporation alters the final color, taste, aroma and nutritional characteristics of reconstituted juice. Therefore, the present study was carried out to evaluate the following points: 1. Evaluation of the use of enzymatic treatment in combination with serum pulp method for concentration of Valencia orange juice and the impact of this process on chemical composition and volatile flavor compounds. 2. The effect of pasteurization on the physicochemical properties and volatile flavor compounds of Valencia orange juice, pulp and serum. Both unpasteurized orange juice and serum separated from it was concentrated by a rotary evaporator under vacuum.