【作者】 贺江；

【导师】 樊明涛；

【作者基本信息】 西北农林科技大学 ， 食品科学， 2008， 硕士

【摘要】 我国是世界上苹果生产大国,每年有大量的残次落果。充分利用这些残次落果是进一步提高苹果价值的有效途径之一。苹果醋是近年来苹果综合利用开发的新产品,它既具有普通食醋防病健身之功效,又具营养价值高、醋香浓郁、果香扑鼻等诸多特色,除用做调味品之外,还可用做饮料、保健品、美容护肤品等。所以,苹果醋的开发是解决残次落果的可行途径之一。苹果醋的酿造方法有多种,固态发酵法产品品质好,但发酵速度慢;液态发酵法发酵速度快,但产品品质不佳;固定化微生物发酵产品品质一般也较差,但它易于实现连续生产,且不同批次间的产品质量稳定。本文旨在结合上述三种发酵技术各自的特点,提出采用多菌种共固定技术酿造苹果醋,从而解决产品品质与发酵速度之间的矛盾。主要研究结果如下:(1)以海藻酸钠作为载体对微生物进行固定的最适固定化条件为:氯化钙浓度0.05 mol/L,海藻酸钠浓度6%,并添加少量浓度6%明胶(6%海藻酸钠:6%明胶=9.0:1.0)。(2)用海藻酸钠制备的微生物固定化颗粒具有较好的稳定性,固定化酿酒酵母1450连续使用17次(17天),固定化醋酸菌AS1.41连续使用4次(28天)发酵性能均无显著下降;固定化酿酒酵母1450低温(4℃)贮存6周,发酵性能无显著下降,固定化醋酸菌AS1.41在低温(4℃)贮存一个月后,仍保持一定强度的发酵性能。(3)当采用菌种比例为酿酒酵母1450,60%,产酯酵母AS2.300,30%,乳酸菌,10%的多菌种共固定化颗粒进行酒精发酵时,最终可获得品质较优的苹果醋。而采用酵母菌和醋酸菌的共固定化颗粒进行苹果醋酿造时,发酵性能不能长时间稳定。(4)采用250mL三角瓶作为发酵容器,多菌种共固定化技术酿造苹果醋的最适工艺条件为:酒精发酵阶段:接种量15%,发酵温度30℃,初始pH4.0;醋酸发酵阶段:接种量10%,底物浓度5.0%vol,发酵温度32℃,摇床转速180~200 r/min,装液量80mL。(5)多菌种共固定化酿造苹果醋除了可以提高酿造速度外,还能够避免液态发酵和固定化技术所酿苹果醋在品质上的不足,其不挥发性酸、氨基态氮的含量较液态发酵、固定化发酵所得苹果醋有较大的提高,其风味成分组成与固态发酵所得苹果醋相似。所建立的多菌种共固定酿造苹果醋的技术在放大试验中,完成酒精发酵只需要24 h,醋酸发酵只需要7天时间,发酵速率比文献报道的速度有一定提高。(6)秦冠和富士等品种较适宜于酿造苹果醋。更多还原

【Abstract】 China is a main country in the world for apple producing. A large number of fallen and substandard fruits need to be treated every year. Apple vinegar is a new type of product developed form apple utilization. It not only has the preventive and hygienical effectiveness of ordinary vinegar, but also has high nutritional value, and rich of vinegar and fruit fragrance, besides as condiment, it can also use for beverage, health goods, and cosmetic and skin care products production. Therefore, apple vinegar production will be a viable means for fallen and substandard fruits utilization. There are many methods for apple vinegar brewing, The speed of solid-state fermentation is slow, but can get a good quality vinegar; liquid fermentation is faster, but the quality of its products is generally poor; vinegar brewed by immobilized cell fermentation is also generally poor, but the prominent features of this brewing method is easy to realize continuous processing, and the quality of products from different batch is homogeneous. The aim of this work was to combine the characteristics of the aforesaid three vinegar brewing methods, and develop a new type of apple vinegar brewing method to solve the contradiction between the quality of product and the speed of fermentation. The main research conclusions in this study showed as follow:(1) The optimum conditions for microorganism immobilization while sodium alginate as a carrier was keep the concentration of calcium chloride at 0.05 mol / L, concentration of sodium alginate at 6%, and add a small amount of 6% gelatin in sodium alginate (6% alginate sodium:6% gelatin = 9.0:1.0).(2) The stability of microorganism immobilized particles made by sodium alginate was fine. Fermentation performance of immobilized Saccharomyces cerevisiae 1450 was not significant decline for use of 17 times (17days) or store under low temperature (4℃) for six weeks. And fermentation performance of immobilized acetic acid bacteria AS1.41 was not significant decline for continuous use four times (28 days), and still maintain a certain intensity for store under low temperature (4℃) for a month.(3) Apple vinegar with good quality can obtain at the end, when multi-microorganisms co-immobilized particles with a ratio of strains of Saccharomyces cerevisiae 1450, 60%, aroma-improving yeast AS2.300, 30%,and lactic acid bacteria, 10 % was used for alcohol fermentation,. But, when multi-microorganisms co-immobilized particles of Saccharomyces cerevisiae 1450 and acetic acid bacteria AS1.41 was used for apple vinegar brewing, the fermentation performance can not be keep for a long time.(4) The optimal process conditions for apple vinegar brewing by co-immobilized technology while 250 mL flask as fermentation vessels was keep inoculate amount at 15%, fermentation temperature at 30℃and initial pH at 4.0 in alcoholic fermentation stages; and keep inoculate amount at 10%, alcohol concentration at 5.0%, fermentation temperature at 32℃, shaker speed betwwen 180 to 200 r/min and loaded liquid volume at 80 mL in acetic acid fermentation stages.(5) In addition to improving the velocity of fermentation, the multi-microorganisms co-immobilization technology developed in this study also can improving the quality of apple vinegar. The amount of unvolatile acids and amino-state N in apple vinegar produced by this type of technology was more than apple vinegar produced by liquid fermentation technology and immobilization technology and the composition of flavor components was similar to apple vinegar produce by solid-state fermentation technology. Only 24 hours was needed for alcoholic fermentation, and seven days for acetic acid fermentation in amplification test, the fermentation rate was greater than reported in the literature.(6) Qin-guan and Fuji were suitable for apple vinegar brewing.更多还原