Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/50811
標題: Improvement of freezing resistance and freeze-drying suitability of traditional tofu
傳統豆腐抗凍性與冷凍乾燥適性的改善
作者: 劉家芳
Liu, chia-Fang
關鍵字: 傳統豆腐
curdlan
冷凍乾燥
反應曲面法
質地輪廓分析
冷凍
traditional tofu
curdlan
freeze-drying
response surface methodology
texture profile analysis
freeze
出版社: 食品科學系
摘要: ABSTRACT Traditional tofu is liable to deterioration and possesses no freezing resistance. Its texture becomes sponge- like after freezing. This makes itinconvenient in transportation, storage, and consumption. Curdlan is a bacterial polysaccharide which is composed mainly of β-1,3- glucosidic linkage. A rigid and elastic thermal irreversible gel could be formed from its suspension by heating above 80℃. Excellent gel strength couldbe maintained by the gel after freezing and thawing. The gel would result in syneresis when it is stored, and the syneresis of curdlan gel could bedecreased by the addition of waxy corn starch. On the other hand, concentration of coagulant required was also affected owing to thebinding capacity of curdlan. Therefore, traditional tofu with freezing resistance and higher water holding capacity was developed in this study.Effects of curdlan(0 ~1.5%), waxy corn starch(0 ~1.5%), and coagulantconcentrations(0.5 ~1.5%) on traditional tofu were studies by using response surface methodology (RSM) and a three-variable and three-leveldesign. The objectives were to obtain a traditional tofu with freezingresistance by the study of their interactions and by the determination of some optimum conditions. On the other hand, freezing temperature(-5℃ ~-45℃) was combined with those three above-mentioned conditionsin the freeze-drying study in order to develop a dehydrated product with good qualities and to expand the applicability of traditional tofu in modern foods. Items tested included gel strength, water holding capacity,rehydration ratio, Instron texture profile analysis (TPA), as well assensory evaluation and scanning electron microscopic examination. Besides, the studies of pure curdlan was also be performed by using RSM. Differences among those processes was going to be compared and studied,and actions of curdlan in application was going to be further investigatedand elucidated. Results showed that the optimum processing conditions of frozen traditional tofu were curdlan 0 ~ 0.2%, waxy corn starch 0.94 ~ 1.5%,and coagulant 1%. The optimum processing conditions of freeze-dried traditional tofu were found to be curdlan 0 ~ 0.18%, waxy corn starch 1.31~1.5%, coagulant 0.5%, and freezing temperature -25℃.
中 文 摘 要 傳統豆腐十分容易腐敗,而且不具抗凍性,冷凍貯藏之 後會形成海棉狀的質地,喪失豆腐特有的質感。因而造成產銷、貯藏及消 費上的許多不便。curdlan是由微生物所產生的一種多醣類,乃是葡萄糖 以β-1,3-醣甘鍵連接而成。其懸浮液在80℃以上加熱可形成堅實、有彈 性之熱不可逆性膠體,此膠體經冷凍、解凍後發現仍能保持良好的凝膠強 度。而糯玉米澱粉的添加可以防止離水。此外,由於curdlan本身就具有 結著性,對豆腐製造時所需的凝結劑添加量會有影響。因此本研究擬將 curdlan與糯玉米澱粉應用於傳統豆腐的製造上,以提高其抗凍性及保水 力,利用反應曲面法(RSM)對傳統豆腐製程中所用curdlan濃度(0 ~ 1.5%)、糯玉米澱粉濃度(0 ~ 1.5%)及凝結劑濃度(0.5~1.5%)進行三因子 三層階的試驗,探討其間的交互作用並進行最適化,嘗試開發具抗凍性的 冷凍傳統豆腐。此外,將前述三因子再配合上預備凍結溫度(-5℃ ~ -45℃),進行四因子三層階的試驗,嘗試開發具良好品質的冷凍乾燥豆腐 ,以拓展傳統豆腐在現代化食品中的應用性。測定項目包括凝膠強度、保 水力、復水性及Instron質地輪廓分析(TPA)等物理分析,以及官能品評和 掃描式電子顯微鏡觀察。此外,並以反應曲面法同時對純curdlan的作用 進行探討比較,嘗試藉由相互間的差異來了解curdlan在製造應用中的作 用情形。結果發現冷凍傳統豆腐的最適加工條件為:curdlan濃度0 ~ 0.2%,糯玉米澱粉濃度0.94 ~ 1.5%,凝結劑濃度 1%。冷凍乾燥傳統豆腐 的最適加工條件為:curdlan濃度0 ~ 0.18%,糯玉米澱粉濃度1.31 ~ 1.5%,凝結劑濃度0.5%,預備凍結溫度-25℃。
URI: http://hdl.handle.net/11455/50811
Appears in Collections:食品暨應用生物科技學系

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