Abstract: In order to investigate the effect of different thawing methods on the quality of quick frozen Chimonobambusa quadrangularis shoot (QFCQS), five thawing methods, namely, microwave thawing, ultrasonic thawing, natural thawing, thawing in a water bath at 20 ℃ and thawing in a water bath at 50 ℃ were used to treat QFCQS. The changes in the drip loss, hardness, color, basic nutrients, peroxidase (POD), polyphenol oxidase (PPO) and phenylalnine ammonialyase (PAL) activity and microscopic structure of QFCQS were measured after thawing. The results showed that thawing time was significantly different among the five thawing methods (P < 0.05). Microwave thawing reduced the thawing time by 97% compared with natural thawing. The drip loss after thawing was as follows: natural thawing > thawing in a water bath at 50 ℃ > microwave thawing > thawing in a water bath at 20 ℃ > ultrasonic thawing. Furthermore, QFCQS with higher drip loss after thawing had lower hardness. After ultrasonic thawing, the color difference (?E) of QFCQS was 1.72, and the color change was the smallest. Meanwhile, the nutritional quality was maintained to the largest extent, and the content of vitamin C was 1.35 times higher than that of natural thawing. PPO activity in QFCQS was not significantly changed among the five thawing methods (P > 0.05), while the activities of POD and PAL were the lowest after ultrasonic thawing. As shown in scanning electron microscope (SEM) images, the tissue structure was destroyed to the greatest extent after natural thawing but was maintained well after ultrasonic thawing. The results of this study can provide a theoretical basis for the selection and application of a suitable thawing method for QFCQS.

Key words: thawing methods, Chimonobambusa quadrangularis shoot, drip loss, hardness, microstructure