Effects of germinated and nongerminated rice grains on storage stability of pressurized purple rice beverages with Lactobacillus casei 01 supplement

Abstract

© 2020 Wiley Periodicals, Inc. Changes of phytochemicals and probiotic in the pressurized purple rice beverages on storage were compared with heated products. Germinated or nongerminated purple rice were used to produce the beverages which were subjected to either pressurization at 500 MPa for 20 min at 25°C or heat at 95°C for 20 min. Subsequently, encapsulated Lactobacillus casei 01 was aseptically added to the beverages which were stored at 4°C for 4 weeks. It was found that germination led to reduction of anthocyanins, phenolic compounds and antioxidant capacity, but enhanced GABA and γ-oryzanol contents. Pressurized beverages were lighter in color than thermally treated ones; however, their color changed faster than the heated samples during storage. Phytochemicals such as anthocyanins, phenolics, and DPPH radical inhibitors in both pressurized (germinated and nongerminated) beverages had the same trends of decreasing, but GABA and γ-oryzanol were stable on storage. L. casei 01 remained at about 8 log CFU/ml. Practical applications: Compared to ordinary rice, purple rice contains higher contents of phytochemicals such as anthocyanins and phenolic compounds. In particular, germinated grains have high concentrations of health promoting aminobutyric acid and γ-oryzanol. To enrich its health benefits, an encapsulated probiotic can be added to the processed beverages and pressurization is a promising process to preserve these phytochemicals. Currently, pressure treatment, though relatively expensive, is becoming more widely used in food manufacturing. Since its benefits in retaining important nutrients and, as this study shows, phytochemicals are significant, and justify the increased costs that health conscious consumers will pay. The increasing popularity of functional foods suggest the processes researched in this study could be easily taken up and exploited in the market place to produce high-quality purple rice products.