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 7 kGy) 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 3 kGy 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 2 kGy 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.

Effect of γ-irradiation on physico-chemical and microbiological properties of mango (Mangifera indica L.) juice from eight Indian cultivars

“…Similarly, Miller and McDonald (1999) have demonstrated that there was no alteration in pH of papaya juice that had undergone irradiation treatment. In contrast, Sadoughi, Karim, Hashim, Zainuri, and Ghazali (2012) observed there was no significant difference (P 40.05) in the pH of onion puree at different irradiation doses (1-7 kGy) from the initial value of pH 4.55, nor was there any significant change during the 28-day storage period.…”

“…Fan et al (2005) reported irradiation doses at 0.5 and 1.0 kGy did not change the TA values of sliced apples, which were initially treated with 7% calcium ascorbate. In contrast, Sadoughi et al (2012) observed that there was no significant difference (P 40.05) in the TA of onion puree at different irradiation doses (1-7 kGy). The identification and quantitative analysis of major organic acids in fruits is considered very important for quality evaluation of food and beverages (Hasib, Jaouad, Mahrouz, & Khouili, 2002).…”

“…In this study different doses of γ-irradiation had no significant effect on the content of these organic acids in all cultivars of mango juice samples (Table 3). Similarly, Sadoughi et al (2012) reported no significant changes (P 40.05) in the contents of malic, oxalic, pyruvic, citric and glutamic acids in onion puree immediately after being exposed to different doses of γ-irradiation and during cold storage. Opposite to these findings, Kim and Yook (2009) reported that irradiated kiwi fruits showed little effects on the organic acid content.…”

“…The present results are in close agreement with the findings of Shahbaz et al (2014), who reported TSS of the pomegranate juice was not affected at different irradiation doses (0.4, 1 and 2 kGy) studied. Sadoughi et al (2012) reported no significant change (P 40.05) in the TSS of onion puree as a consequence of γ-irradiation. Kim and Yook (2009) reported that exposure to radiation doses up to 3 kGy did not affect the TSS content of kiwi fruits at week 0, but irradiated fruits showed a decrease in the TSS content with increasing irradiation dose during storage.…”

Combined Effects of γ-Irradiation and Ascorbic Acid on the Physicochemical Properties, Microbial Stability and Aroma Profile of Onion Puree During Storage

“…γ‐Irradiation of onion puree at 2 kGy has been found to have a number of advantages (Sadoughi et al . ). The most important effect of this process is a reduction in bacteria and yeast counts making it safe for at least 1 month at 4C.…”