Characterization of the physicochemical, phytochemical, and microbiological properties of steam cooked beetroots during refrigerated storage

In the present study, steam cooked beetroots commercially available, were subjected to analyses of pH, total acidity, total phenolic content, antioxidant activity and EC50, betacyanins and betaxanthins content expressed as betalains, along with TVC (total viable count) during refrigerated storage for 9 days. The aim of the study was to characterize the product by means of microbiological, physicochemical, and phytochemical content analyses, and investigate whether there were any differences in the measured parameters during refrigerated storage. Results showed that the shelf-life of steam cooked beetroots was estimated to be 3 days (log CFU/g < 7), whereas in the 6th day of storage the TVC population reached 8.47 log CFU/g. Among the physicochemical parameters studied, pH and total acidity varied significantly (p < 0.05) during refrigerated storage. The same holds for total phenolic, betacyanins, betaxanthins, and betalains content, whereas only antioxidant activity and EC50 did not show any significant (p > 0.05) differences during refrigerated storage as indicated by one-way analysis of variance. Multivariate analysis of variance along with linear discriminant analysis and k-nearest neighbors indicated that steam cooked beetroots could be classified according to storage time by a high prediction rate using the statistically significant parameters. Data were further evaluated using a non supervised chemometric technique, and comparable results were obtained. Finally, the retaining of antioxidant activity, total phenolic content along with the pigment content in good levels after the spoilage of the product, indicate the possibility of using steam cooked beetroots as a potential food-waste matrix, after the proper processing.