聚乳酸薄膜包装袋对杨桃保鲜效果的研究

Effect of polylactic acid film bags on the preservation of Carambola

杨桃分别用聚乳酸(PLA)和聚乙烯(PE)包装袋包装,包装方式采用气调包装和真空方式两种,处理好后将样品置于20℃,相对湿度95%的环境中贮藏,以未包装杨桃为对照,测定了杨桃贮藏过程中包装袋中O2和CO2含量,失重率、褐变度、可滴定酸含量、pH、可溶性固形物、多酚氧化酶(PPO)活性、抗坏血酸等变化,研究PLA薄膜包装袋包装杨桃的保鲜效果。结果表明,在真空包装对照组中,各项数据差别很小,但其对杨桃的保鲜效果普遍优于气调包装。在气调包装对照组中,气相色谱分析显示PLA袋中CO2体积分数比PE高,O2体积分数低。11 d后,PLA气调包装袋中杨桃褐变度和PPO活性为11.4%和2.3 U/min.g,低于PE气调包装的55.2%和2.9 U/min.g;有机酸分解为0.14%,pH为4.74,酸值高于PE气调包装;同时,PLA包装中杨桃的可溶性固体物和V_C含量均高于PE包装袋中杨桃。由此说明,PLA包装确实可以有效延长杨桃的货架期。

Carambolas were vacuum and modified atmosphere packaged with Polylactic acid（PLA）and Polyethylene （PE） bags,the packs were stored in temperature humidity chamber at temperature 20℃and RH of 95% ,unpacked carambolas were used as controls.The following fruit quality parameters were measured to study the effect of PLA film bags on the preservation of carambola in the experiment：volume fraction,weight loss, browning degree,total titratable acidity, pH, soluble solid, polyphenol oxidase （PPO） activity and ascorbic acid. Experimental results showed that data difference between PLA and PE vacuum packagings was small, but vacuum packaging had a better fresh-keeping effect than modified atmosphere packaging. In the control group of modified atmosphere packaging ,gas chromatograph showed that the O2 content of the PLA packaging was lower than PE packaging in all groups,while the CO2 content was higher.On the llth day,the browning degree and PPQ activity of carambolas in PLA packaging were 11.4% and 2.3 U/min.g,lower than 55.2% and 2.9 U/min.g of PE packaging.The total titratable acidity was 0.14%,pH was 4.74, higher than that of PE packaging after 11 days. Furthermore, carambolas in PLA packaging exhibited high soluble solid and ascorbic acid content.The result showed that PLA packs could extend the sshelf life of carambolas.