Application of Ascorbic Acid and Mild Heat Shock to Improve Shelf Life and Ensure Microbial Safety of Sliced Radish (Raphanus sativus L.)

Abstract

Effects of hurdle technologies (ascorbic acid 2%, 5min+mild thermal shock 50C, 1.5min) on physicochemical, nutritional and antioxidant parameters of sliced radishes during 7 days of storage were investigated. At day 7, enzyme activities for treated samples were much lower than for control; whereas the browning parameters increased. For treated samples, b*; value remained constant until day 4, and a significant increase was observed at day 7. The hurdles reduced the initial microbial populations on radish slices, and maintained that for 4 days under refrigerated storage. Treated samples had higher content of flavonoids compared to control samples during all storage. Oxygen radical absorbance capacity assay results were positively correlated to total phenolic content (TPC) and total flavonoids content (r2=0.712 and r2=0.750, respectively). In addition, a high correlation was observed for TPC and 1,1-diphenyl-2-picrylhydrazyl (r2=0.996). More investigations are needed to characterize bioactive compounds of radish to include them in nutraceutical formulations. Practical Applications: Although radish composition presents highly medicinal and nutritional values, reports about its quality parameters (physicochemical, nutritional and antioxidant) during minimal processing and refrigerated storage are still scarce. Therefore, and in response to consumer preference, low cost and safer preservation hurdles, application of ascorbic acid and mild heat shocks were evaluated in this investigation. Polyphenol oxidase activities, color, vitamin C, total phenolic compounds, antioxidant capacity, browning potential as well as microbiological aspects were assessed during 7 days of storage. Based on results, the application of this combination of treatments improved relevant sample parameters compared to control samples, which are related to functional properties of these roots in an attempt to maintain consumer's health and prevent different diseases.