Background: Young barley grass powder contains abundant nutrition and its antioxidant substances are severely impaired by radiation (60 Co) sterilization. To overcome product quality degradation, radiofrequency pasteurization was conducted using pilot-scale radiofrequency equipment (27 MHz, 6 kW) with electrode gaps of 12, 14 and 16 cm, while hot-air (80 °C) pasteurization was used for comparison.
Results: Assessment suggested that uneven radiofrequency heating was improved for the 14 cm electrode gap. With an increase of electrode gap, microbial inactivation needs more energy consumption. A minimum energy consumption of 970 J g-1 was required for 1 log-reduction of colonies. Radiofrequency pasteurization retained better antioxidant substances, lightness (L*), green color (a*) and odors in barley grass powder, compared with hot-air sterilization. Contents of flavonoid and chlorophyll were 5.82 and 4.87 g kg-1 respectively, using the 14 cm electrode gap. Additionally, radiofrequency pasteurization led to an improvement in sourness, bitterness and umami tastes.
Conclusions: Radiofrequency pasteurization would be a superior alternative for the pasteurization of barley grass powder. © 2019 Society of Chemical Industry.
Keywords: antioxidants; barley grass powder; energy consumption; microbial reduction; radiofrequency.
© 2019 Society of Chemical Industry.