Improving the safety and quality of raw tuna fillets by X-ray irradiation. (February 2016)

• Record Type: Journal Article
• Authors: Mahmoud, Barakat S.M.; Nannapaneni, Rama; Chang, Sam; Wu, Yuwei; Coker, Randy
• Is Part Of: Food control. Volume 60(2016:Feb.)
• Page Start: 569
• Page End: 574
• Publication Date: 2016-02
• Subjects: Improving -- Safety -- Quality -- Tuna -- X-ray irradiation; Food -- Quality -- Periodicals; Food -- Analysis -- Periodicals; Food handling -- Periodicals; Food industry and trade -- Quality control -- Periodicals; Aliments -- Industrie et commerce -- Qualité -- Contrôle -- Périodiques; Aliments -- Qualité -- Périodiques; Aliments -- Analyse -- Périodiques; Hygiène alimentaire -- Périodiques; Food -- Analysis; Food handling; Food -- Quality; Periodicals; Electronic journals; 664.07
• DOI: 10.1016/j.foodcont.2015.08.039
• Languages: English
• ISSNs: 0956-7135

Abstract

Abstract: In this study, raw tuna fillet (25 g) samples were inoculated by immersing in 0.1% peptone water that contained 10 8−9 CFU ml −1 of a three-strain mixture of Salmonella enterica for 1 min. The samples were then air dried at 22 °C for 30 min (to allow bacterial attachment) in the biosafety cabinet and were packaged separately in sterilized bags prior to X-ray treatments (0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 kGy). The surviving Salmonella populations on raw tuna fillets samples were evaluated using a nonselective medium (tryptic soy agar) for 6 h with xylose lysine desoxycholate (XLD) selective medium overlay. The plates were then incubated for an additional 18 h at 37 °C. Finally, the colonies were counted and the results were expressed as log CFU g −1 . Furthermore, un-inoculated tuna samples (25 g) were packaged separately in sterilized bags and exposed to the lowest and highest X-ray doses (0.0 and 6.0 kGy), then stored at 5 °C, 10 °C or 25 °C for 25, 15 or 5 days, respectively. On the testing-dates, samples were withdrawn and microflora (psychrotrophic and mesophilic) counts, quality [color (using Hunter colorimeter) and texture (using Instron machine)] were evaluated. The results indicated that more than a 6 log CFU reduction of Salmonella population being achieved with 0.6 kGy X-ray treatment. Furthermore, treatment with X-ray significantly reduced the initial inherent microbiota on raw tuna fillets and inherent levels were significantly (p < 0.05) lower than the control samples throughout the shelf-life storage at 5, 10 or 25 °C for 25, 15 or 5 days, respectively. There was a significant effect of X-ray treatment on tuna color after treatment (day 0). However, no significant differences (p > 0.05) in color or texture of control and treated samples were observed after (day 0). These results indicated that X-ray is a good preservative technology for seafood products intended to be consumed raw. Highlights: This is the first report that describes inactivation of Salmonella on raw tuna fillets by Xray. X-ray is an effective technology in reducing Salmonella and spoilage microflora in tuna fillets. Tuna color was significantly (p < 0.05) affected by X-ray treatment (day 0). No significant differences (p > 0.05) in color or firmness of control and treated samples were observed after (day 0). Using X-ray, the raw tuna industry can save millions of dollars by avoiding recalls for their products.