草酸对冷藏去壳马蹄笋的保鲜效果及机制研究

为探讨外源草酸延缓采后去壳马蹄笋木质化和褐变的效果及其作用机制,本试验以马蹄笋为试验材料,笋去壳后于水和5 mmol·L^-1草酸溶液中浸泡10 min,而后晾干并于温度6 ±1℃,相对湿度80%~85%条件下贮藏10 d,测定其品质指标以及与木质化、褐变、抗氧化相关酶的活性和基因表达量。结果表明,草酸处理抑制了去壳马蹄笋切面的褐变(P<0.05),延缓了笋肉木质化(P<0.05);草酸处理抑制了呼吸速率、相对电导率、超氧阴离子自由基($O_2^{·-}$)产生速率以及丙二醛(MDA)、过氧化氢(H₂O₂)含量的上升,抑制了苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、肉桂醇脱氢酶(CAD)、多酚氧化酶(PPO)的活性及其编码基因的相对表达量(P<0.05),提高了超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性及其编码基因的相对表达量。综上,草酸处理能够有效抑制采后去壳马蹄笋的木质纤维化和褐变,延缓品质劣变。本研究结果为草酸在马蹄笋采后保鲜的应用提供了理论依据。

Effects of Oxalic Acid on Edible Quality of Bamboo Shoots (Bambusa oldhami) Without Sheaths During Cold Storage and the Related Mechanism

To evaluate the effects of oxalic acid treatment on the edible quality of bamboo (Bambusa oldhami ) shoots during postharvest, fresh bamboo shoots without sheaths were soaked in a 5 mmol·L^-1 oxalic acid solution for 10 min and then stored at (6±1)℃ under 80%-85% relative humidity (RH) for 10 d. Quality parameters and activities of key enzymes and gene expression involved in lignification and browning of bamboo shoots were periodically determined during cold storage to investigate the related mechanism. The results indicated that oxalic acid treatment slowed down the increase rates of flesh firmness and contents of cellulose and lignin, delayed the wound browning, enhanced membrane integrity, reduced respiration,the production rate of superoxide anion ($O_2^{·-}$) and the content of hydrogen peroxide (H₂O₂). It also decreased the activities of phenylalanine ammonialyase (PAL), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD) and polyphenol oxidase (PPO) and the expression of their encoding genes during cold storage, enhanced the activities of superoxide dismutase(SOD)and catalase(CAT)and up-regulated the expression of their encoding genes. It was suggested that these regulation effects of oxalic acid on enzymatic activities and the expression of encoding genes may collectively contribute to the reduction of lignification and browning and consequently benefit the edible quality of bamboo shoots during cold storage. This study provided a theoretical foundation for the application of oxalic acid treatment on bamboo shoots storage.