Nakatsu Sayaka, Shimoda Mitsuya, Shibata Kenya, Kajihara Ryo, Ishihara Masako, Sakamoto Koji
Food Technology Research Center, Hiroshima Prefectural Technology Research Inst, 12-70 Hijiyamahon-machi, Minami-ku, Hiroshima, 732-0816, Japan.
J Food Sci. 2014 Mar;79(3):E333-41. doi: 10.1111/1750-3841.12358. Epub 2014 Jan 23.
Freeze-thaw impregnation is a technique used for the rapid impregnation of substances into foodstuffs. Freeze-thaw impregnation with macerating enzymes has been applied to soften foodstuffs, while retaining their original shapes and flavors. In this study, we found that co-impregnation with citrate ions and macerating enzymes significantly facilitated the softening of root crops. When burdock roots were processed by the impregnating solution at pH 4.0-5.0, co-impregnated burdock roots exhibited 1/6-1/3 firmness values compared with burdock roots impregnated with only enzymes. The impregnation with citrate ions alone at pH 4.0 to 5.0 did not soften burdock roots. The firmness of burdock roots was positively correlated with the amount of water-insoluble calcium in the samples. The results suggested that the degradation of pectins by pectinolytic activities could promote contact with citrate to bridging-calcium ions interacting with the pectin chains. Therefore, the softening by the synergistic effect of citrate ions and macerating enzymes was related to the amount of pectins contained in root crops. That is, the synergistic effect was significant with burdock roots and carrots (from which 50% of polysaccharides are pectins) unlike with lotus rhizomes and bamboo shoots (from which 30% and 10% of polysaccharides are pectins, respectively).
Freeze-thaw impregnation with macerating enzymes and citrate ions can be applied for the production of care foods which can be eaten without chewing. The softened products induce the pleasure of eating for consumers because their original shapes and flavors are retained.
冻融浸渍是一种用于将物质快速浸渍到食品中的技术。用浸渍酶进行冻融浸渍已被应用于软化食品，同时保留其原始形状和风味。在本研究中，我们发现柠檬酸根离子与浸渍酶共同浸渍可显著促进块根作物的软化。当牛蒡根在pH 4.0 - 5.0的浸渍溶液中处理时，与仅用酶浸渍的牛蒡根相比，共同浸渍的牛蒡根硬度值降低至1/6 - 1/3。在pH 4.0至5.0单独用柠檬酸根离子浸渍不会软化牛蒡根。牛蒡根的硬度与样品中不溶性钙的含量呈正相关。结果表明，果胶分解活性对果胶的降解可促进与柠檬酸的接触，从而使柠檬酸与果胶链相互作用的桥连钙离子增加。因此，柠檬酸根离子和浸渍酶的协同作用导致的软化与块根作物中果胶的含量有关。也就是说，与莲藕和竹笋（其多糖分别为30%和10%是果胶）不同，柠檬酸根离子和浸渍酶的协同作用在牛蒡根和胡萝卜（其50%的多糖是果胶）中很显著。
用浸渍酶和柠檬酸根离子进行冻融浸渍可应用于生产无需咀嚼即可食用的护理食品。软化后的产品能保留其原始形状和风味，从而给消费者带来进食的愉悦感。
