Xiaohuang Cao1,2,3, Min Zhang1,2, Bimal Chitrakar1, Arun S Mujumdar4, Qifeng Zhong5, Zhushan Wang6, Liping Wang1. 1. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China. 2. International Joint Laboratory on Food Safety, Jiangnan University, Wuxi city, Jiangsu Province, China. 3. Jiangsu Province Key Laboratory of Advanced Food Manufacturing Equipment and Technology, Jiangnan University, Wuxi city, Jiangsu Province, China. 4. Department of Bioresource Engineering, Macdonald Campus, McGill University, Sainte-Anne-e de Bellevue, Canada. 5. Haitong Food Group Company, Cixi, China. 6. Jiangsu Dingneng Food Company, Xinghua, China.
Abstract
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.
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.