半干型桑叶菜的加工工艺条件优化试验
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摘要
为延长桑叶菜的货架期并最大程度保留其营养和活性成分,以叶绿素、总酚含量及感官品质复水比为考核指标,通过单因素试验选择半干型桑叶菜加工工艺的最优烫漂和热风干燥条件,通过正交试验确定用于桑叶渗透脱水的水分活度降低剂的最优组合。优化的桑叶烫漂和热风干燥条件是:烫漂温度98℃,烫漂时间1.5 min,热风干燥温度65℃。桑叶在此条件下烫漂和干燥,能够较好地保持原有色泽和复水性能以及减少活性成分的损失,且加工过程的能耗也较低。最优的水分活度降低剂组合为氯化钠30 g/L、丙三醇30 g/L、葡萄糖90 g/L、海藻糖40 g/L。用优化的水分活度降低剂组合溶液对桑叶进行渗透脱水处理,可有效减少叶绿素的损失和改善桑叶在热风干燥时水分蒸发导致组织收缩变硬的缺陷,使桑叶菜的水分活度达到安全贮藏要求。
To prolong the shelf life of mulberry leaf vegetables and maximize the retaining of nutritional and active ingredients,chlorophyll content,total phenol content and rehydration ratio were taken as indexes to conduct single-factor test for selecting the optimum blanching and hot-air drying conditions for semi-dried mulberry leaf processing,and to conduct orthogonal test for determining the optimum combination of water activity reducing agents for osmotic dehydration of mulberry leaf. The optimized blanching and hot-air drying condition is blanching at 98 ℃ for 1. 5 min and hot air drying at 65℃. Mulberry leaves blanched and dried under this condition can keep the original color and rehydration property and reduce the loss of active components,and the overall energy consumption is low. The optimal combination of water activity reducing agents is sodium chloride 30 g/L,glycerol 30 g/L,glucose 90 g/L,and trehalose 40 g/L. Processing of mulberry leaf through osmotic dehydration with the optimized combination of water activity reducing agents can effectively reduce the loss of chlorophyll and improve the quality of mulberry leaves in hot-air drying process by preventing the leaves from shrinking and hardening after moisture evaporating. Water activity of the processed mulberry leaf vegetables can meet the requirement for safe storage.
To prolong the shelf life of mulberry leaf vegetables and maximize the retaining of nutritional and active ingredients,chlorophyll content,total phenol content and rehydration ratio were taken as indexes to conduct single-factor test for selecting the optimum blanching and hot-air drying conditions for semi-dried mulberry leaf processing,and to conduct orthogonal test for determining the optimum combination of water activity reducing agents for osmotic dehydration of mulberry leaf. The optimized blanching and hot-air drying condition is blanching at 98 ℃ for 1. 5 min and hot air drying at 65℃. Mulberry leaves blanched and dried under this condition can keep the original color and rehydration property and reduce the loss of active components,and the overall energy consumption is low. The optimal combination of water activity reducing agents is sodium chloride 30 g/L,glycerol 30 g/L,glucose 90 g/L,and trehalose 40 g/L. Processing of mulberry leaf through osmotic dehydration with the optimized combination of water activity reducing agents can effectively reduce the loss of chlorophyll and improve the quality of mulberry leaves in hot-air drying process by preventing the leaves from shrinking and hardening after moisture evaporating. Water activity of the processed mulberry leaf vegetables can meet the requirement for safe storage.
引文
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[2]曹晖.高含水率脱水猕猴桃和菜心的加工与安全贮藏研究[D].无锡:江南大学,2008
[3]NEGI P S,ROY S K.Effect of blanching and drying methods onβ-carotene,ascorbic acid and chlorophyll retention of leafy vegetables[J].LWT-Food Sci Technol,2000,33(4):295-298
[4]JULKUNEN-TIITTO R.Phenolic constituents in the leaves of northern willows:methods for the analysis of certain phenolics[J].J Agric Food Chem,1985,33(2):213-217
[5]刘春泉,卓成龙,宋江峰,等.毛豆仁低温冻盛期叶绿素和色泽降解动力学[J].江苏农业学报,2011,27(4):858-862
[6]沈维治,廖森泰,邹宇晓,等.桑叶酚类物质的变化规律研究[J].中草药,2010,41(11):1890-1892
[7]龙成树,刘清化,李浩权,等.基于闭式热泵干燥机桑叶菜干燥工艺探讨[J].食品科技,2015,40(11):53-57