Study On Immobilizing Yeast Of Cider

China has the largest production of apple. However, how to deeply process apple has become a crucial problem in our nation. As one of deeply processed products of apple, cider is attracting more and more attentions all over the world, including its research and production. In order to better the traditional processing technics and realize continuous fermentation of cider, a novel method that immobilizing cells was applied to make cider.This study was systematically carried out and the results were shown below.(1) Compared with beer yeast 7^# and wine yeast 3^# which are frequently used to ferment cider in China, ten candidates of cider yeast (P₆,P₈,P₁₁,P₁₄,P₁₅,W₂₅,W₃₈,W₄₁,W₅₂ and W₆₅) in our lab were systematically studied for their colonial morphology and sensory characteristics, fermentation abilities and sensory quality of product. The results indicated that the candidate yeast W₄₁ was the best yeast among ten candidates of cider yeast. Its product was shown to be transparent and had typical flavor of cider with 133.0 mL/L alcohol degrees.(2) Based on our preliminary experiments, three carriers, Alginate-Ca, PVA-Alginate-Ca and ACA, were selected to immobilize cider yeast W₄₁ and beer yeast 7^#. Their physical and fermentative properties were respectively and systematically investigated. The results were shown that ACA was the best carrier to immobilize cider yeast W₄₁ to continuously ferment and had potential applicability in industry.(3) Microencapsular technology was widely applied in many fields, especially in food manufacture. In our continuous investigation on making cider, the technique of preparing microencapsules synthesized by chitosan and sodium alginate to immobilize cider yeast was systematically carried out in this work. Through single factor and orthogonal experiments L₂₇(3¹³), four factors were selected, including concentrations of sodium alginate, CaCl2 and chitosan, and liquefying time, and employed to test their effects on microencapular mechanical strength and penetrability. CONCLUSIONS: The effects of sodium alginate`s concentration on microencapular mechanical strength and penetrability were the most notable, and those of CaCl<sub>2</sub> on ACA`s mechanical strength and chitosan on penetrability were notable. Both interaction between sodium alginate and CaCl₂ and liquefying time had inapparent effects on mechanical strength and penetrability of microencapules. The optimized conditions of preparing microencapsules synthesized by chitosan and sodium alginate to immobilize cider yeast were 2.0% of sodium alginate, 2.0% CaCl₂, 0.2% chitosan and 10min liquefying time.