Effect of γ-irradiation on the physicochemical properties, and microbial and sensory qualities of cold-stored onion puree

Abstract

The present study was conducted to evaluate the effect of different doses (0, 1, 2, 3, 5 and 7kGy) of γ-irradiation on the physicochemical properties (pH, titratable acidity, total soluble solid, color, organic acid content), and also the microbial and sensory qualities of onion puree during cold storage at 4C for 28 days. The different doses of γ-irradiation were found to not have any negative effect on titratable acidity, pH, total soluble solid and organic acid contents of onion puree immediately after irradiation and also during cold storage. Irradiation at 3kGy and above was able to control the development of yeasts and molds in the onion puree, but had negative effects on the color and sensory quality of the onion puree. This study indicates that irradiation at 2kGy reduced microbial counts with minimum adverse effects on color and sensory qualities. PRACTICAL APPLICATIONS: Minimally processed fruits and vegetables are in vogue, but minimal processing may result in undesirable changes in color, taste and appearance because of the transfer of microorganisms from the environment or food handler to the exposed plant tissues. One of the common methods to reduce microbiological contamination level is thermal treatment. However, the use of thermal treatment can destroy nutrients such as thermally unstable vitamins and also the components responsible for the products' flavor and taste. Another well-known method to reduce microbial content in plant-based foods is irradiation. Such nonthermal pasteurization technology can be applied in the processing of fruit and vegetables products such as juices, purees, etc. to avoid the deleterious effects on flavor, color and nutrient value of the foods. © 2012 Wiley Periodicals, Inc.