Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2009
Publication Date: 1/6/2010
Citation: Guan, W., Fan, X. 2010. Combination of sodium chlorite and calcium propionate reduces enzymatic browning and microbial population of fresh-cut ‘Granny Smith’ apples. Journal of Food Science. 75(2):M72-M77. Interpretive Summary: Apple slices which contain antioxidants and other nutrient components, have emerged as popular snacks in food service establishments, school lunch programs, and for family consumption. However, the further growth of the industry is limited by product quality deterioration caused by tissue browning, short shelf-life due to microbial growth and possible contamination with human pathogens during processing. Therefore, this study was conducted to develop treatments to reduce microbial population and tissue browning of ‘Granny Smith’ apple slices. Results showed that an antimicrobial compound, sodium chlorite, is effective in not only eliminating microbes but also inhibiting tissue browning of apple slices. However, the compound caused tissue softening and its anti-browning effect was short-lived lasting only for a few days. Combination of the compound with a calcium-containing food additive was able to improve firmness and freshness of apple slices while reducing population of Escherichia coli artificially inoculated on samples and inhibiting the growth of yeast and mold during storage. Our results showed that the quality of apple slices could be maintained and microbial population could be reduced by combining the two FDA-approved agents. The information is useful to the fresh-cut apple industry in further enhancing microbial safety of the product.
Technical Abstract: Tissue browning and microbial growth are the main concerns associated with fresh-cut apples. In this study, effects of sodium chlorite (SC) and calcium propionate (CP), individually and combined, on quality and microbial population of apple slices were investigated. ‘Granny Smith’ apple slices, dipped for 5 min in CP solutions at 0, 0.5, 1 and 2% (w/v) either alone or in combination with 0.05% (w/v) SC, were stored at 3 C and 10 C for up to 14 days. Color, firmness, and microflora population were measured at 1, 7, and 14 days of storage. Results showed that CP alone had no significant effect on the browning of cut apples. Even though SC significantly inhibited tissue browning initially, the apple slices turned brown during storage at 10 C. The combination of CP and SC was able to inhibit apple browning during storage. Samples treated with the combination of SC with CP did not show any detectable yeast and mold growth during the entire storage period at 3 C. At 10 C, yeast and mold count increased on apple slices during storage while CP reduced the increase. However, high concentrations of CP reduced the efficacy of SC in inactivating E. coli inoculated on apples. Overall, our results suggested that combination of SC with low levels of CP could be used to inhibit tissue browning and maintain firmness while reducing microbial population.