Physicochemical characteristics of kimchi powder manufactured by hot air drying and freeze drying

• Kimchi powder was manufactured by hot air drying and freezing drying.
• During hot air drying the browning index increased with increasing temperature.
• Freezing drying method is more suitable for producing kimchi powder.

Kimchi powder was manufactured by hot air drying at different temperature of 55 °C, 60 °C and 65 °C, and freeze drying until it reached about 10% moisture content. The water absorption index (WAI) and water soluble index (WSI) of freeze dried powder was higher than those hot air dried kimchi powder. Moreover, L*, a* and b* values of hot air dried kimchi powder were lower than those of freeze dried kimchi powder. During hot air drying, the browning index increased with increasing drying temperatures. The highest browning index was found in samples dried at 65 °C with inoculation of mixed Leu. mesenteroides and Lb. sakei. The freeze drying showed the lowest browning index compared to hot air drying (55 °C, 60 °C and 65 °C). In addition, the kimchi powder prepared by freeze dryer clearly received higher scores for overall acceptance than sample prepared by hot air dryer on sensory evaluation. Consequently, the kimchi inoculated Leu. mesenteroides as the starter has a similar quality with the naturally fermented kimchi. These results suggested that freeze drying method is more suitable for producing high quality kimchi powder than hot air drying.