O_2/CO_2气调中CO_2对西兰花叶绿素降解及保鲜作用

Effect of CO_2 Concentration in O_2/CO_2 Controlled Atmosphere on Chlorophyll Degradation and Quality Preservation in Chilled Broccoli

为研究O_2/CO_2气调环境下CO_2对西兰花叶绿素降解及保鲜效果的影响,在固定O_2为50%的前提下,分别设置CO_2体积分数为20%、30%、40%和50%,同时以自然大气为对照,对5℃贮藏条件下西兰花的总叶绿素、叶绿素a和叶绿素b含量,叶绿素还原酶、脱镁叶绿素酶活性,乙醇、乙醛和抗坏血酸含量进行了定期测定。结果表明:过低或过高的CO_2体积分数都会对西兰花贮藏品质造成不利影响,CO_2体积分数过高易造成西兰花无氧呼吸生成乙醇、乙醛;CO_2体积分数过低则造成西兰花叶绿素还原酶、脱镁叶绿素酶活性升高,导致叶绿素迅速降解,引起西兰花黄化和抗坏血酸的损失。本实验条件下,50%O_2+40%CO_2处理可有效延缓西兰花叶绿素降解,且不会造成乙醇、乙醛的积累,达到很好的保鲜效果。

In order to study the effect of CO2 concentration in O2/CO2 controlled atmosphere on chlorophyll degradation and quality preservation in chilled broccoli, fresh broccoli were in atmospheres consisting of 50% O2 and CO2 at four different concentration levels of 20%, 30%, 40% and 50% or air and then stored at 5 ℃. During storage, the contents of total chlorophyll, chlorophyll a, chlorophyll b, ethanol, acetaldehyde and ascorbic acid, and the activities of chlorophyllase and Mg-dechelatase were regularly determined. The results showed that too low or too high CO2 proportion in controlled atmospheres had a disadvantageous effect on the storage quality of broccoli. Too high CO2 could accumulate the contents of ethanol and acetaldehyde through anaerobic respiration. However, too low CO2 could promote the activities of chlorophyllase and Mg-dechelatase, leading to rapid degradation of chlorophyll, yellowing and ascorbic acid loss in broccoli. Under the experimental condition in this study, 50% O2 ＋ 40% CO2 treatment could effectively retard chlorophyll degradation and avoid the accumulation of ethanol and acetaldehyde and therefore have an ideal effect on quality maintenance of stored broccoli.