热处理对鲜切生菜生理生化品质的影响

Effect of Hot Water Treatment on Physiological and Biochemical Quality of Fresh-cut Lettuce

采用35,45,55℃的热水分别处理鲜切生菜1,2,3 min,研究4℃、湿度85%~95%贮藏条件下11 d内,不同温度不同时间的热处理对鲜切生菜呼吸速率、含水量、VC、叶绿素含量、褐变潜力、多酚氧化酶（PPO）活性及感官品质的影响。结果表明,所有热处理（除55℃2 min、3 min外）均能不同程度地延缓水分、VC、叶绿素含量的下降,抑制呼吸速率及PPO活性,维持较低的褐变潜力,保持较好的感官品质。至贮藏期第11 d,55℃1 min热处理的鲜切生菜的呼吸速率仅为（CO2）270.43 mg/（kg.h）,含水量仍高达96.77%;以鲜重计VC含量为5.81 mg/g,叶绿素含量为1.34 mg/g,显著（P〈0.05）高于其他处理;褐变潜力和PPO活性保持在较低水平,分别为0.098 UA/g和16.19 U/kg;感官品质仍有7.67分,具有良好的商品价值。45℃3 min和35℃3 min热处理对保持鲜切生菜的品质也具有一定作用,但作用效果次于55℃1 min;而55℃2 min、3 min热处理会对鲜切生菜造成伤害,加速腐败进程,不适于鲜切生菜保鲜,即以55℃1 min热处理鲜切生菜的生理品质及保鲜效果较好。

The effect of mild hot water treatment on some properties of fresh-cut lettuce during storage at 4 ℃ for 11 days was determined.The fresh-cut lettuce was immersed in heated water（35 ℃,45 ℃,55 ℃） for 1,2,3 min respectively.Markers of quality retention： respiration rate,water,VC and chlorophyll content,potential browning,PPO activity and sensory quality were analysed during storage.All hot water treatments（except 55 ℃ 2,3 min）can control the decline of water content,maintain low respiration rate and high VC content,sensory quality and delay the occurrence of browning to some extent.In the storage period of eleven days,55 ℃ 1 min hot water treatment for fresh-cut lettuce maintained the highest water,VC and chlorophyll contents which were 96.77%,5.81 mg/g（FW）and 1.34 mg/g（FW）respectively,and it had low respiration rate,potential browning and PPO activity,the sensory quality was still 7.67 points.But the use of long period of high-temperature treatment（55 ℃ 2,3 min） showed a negative effect on fresh-cut lettuce.