【作者】 林绍霞；

【导师】 谢宝贵； 江玉姬； 黄晋之；

【作者基本信息】 福建农林大学 ， 蔬菜学， 2008， 硕士

【摘要】 由于银耳熬煮时间长,一般的银耳制品---银耳脯存在高糖,含水量低,质地硬,脆,易损坏包装等问题,这就严重阻碍了银耳及其制品在人们生活中的推广食用。针对银耳脯存在的问题,本文以干银耳为原料对低糖即食银耳品开展了较系统的研究。首先,以多糖损失量和感官品质为指标对干银耳浸发煮制的工艺参数进行优化。接着,从Aw对成品品质影响考虑,对与Aw相关的各因素进行研究,探讨了其保藏特性。最后从Aw和微波杀菌两个方面对低糖银耳即食品的贮存稳定性进行系统的研究,旨在提高银耳脯的品质,使它成为深受人们欢迎的产品。同时还做了对小鼠免疫功能影响的实验。研究结果表明:（1）从银耳浸发煮制过程中多糖损失量最少和感官评定结果最佳两个方面考虑,得出的较佳工艺参数为:水pH6,温度30℃,浸泡25min,0.1MPa蒸煮8min。（2）为控制银耳脯中总糖含量,得到40-45%的低糖品,同时从蔗糖、葡萄糖、葡聚糖对产品的Aw影响考虑,在银耳脯加工过程中,以20%葡聚糖与30%蔗糖混合液作为浸渍液可以得到预期的低糖效果。（3）Aw是影响产品品质的主要因素,而产品的食盐浓度（X₁）、总糖含量（X₂）和水分含量（X₃）均对其有显著的影响,产品的Aw（Y）与食盐浓度、总糖含量和水分含量存在以下的关系:Y=0.73694-0.03867X₁-0.0399X₂+0.08409X₃-0.03869X₃²。（4）Aw是影响低糖即食银耳品稳定性的主要因素,控制即食银耳品Aw在0.645～0.721时,细菌、霉菌、酵母菌生长繁殖均受到抑制,保质期达180d;即食银耳品Aw在0.763～0.813时,细菌生长繁殖仍受到抑制,但是霉菌、酵母菌容易生长繁殖,引起即食银耳品的腐败。（5）聚丙烯包装的即食银耳品50g经800w微波照射120s,对霉菌、酵母菌的杀菌率分别达到82%和71%以上,即食银耳品在室温下可安全贮存至少180d。（6）真空包装对霉菌生长繁殖有明显的抑制作用,对酵母菌的生长繁殖也有一定程度的抑制效果。（7）即食银耳品对小鼠免疫功能的影响实验结果表明:由即食银耳品制成的15%悬浮液在0.75g/kg的剂量下,对小鼠胸腺、脾脏具有明显的增重作用,对血清溶血素含量的增加也有明显的影响;悬浮液在1.5g/kg的剂量下,对提高小鼠碳粒廓清率,增加巨噬细胞的吞噬功能,具有极显著影响。说明即食银耳品能明显地增强小鼠的免疫功能。更多还原

【Abstract】 The long cooking time,high sugar content,slow rehydration,rate,hard texture and potential of package damage of the instant,dried Tremella fuciformis products on the market attribute to its limited sales.These aspects were researched to improve Tremella fuciformis products’ quality in this thesis.This thesis represents a systematic study on low sugar products to improve these aspects in 3 steps.Firstly,balancing polysaccharides leaching and product’s sensory quality,the pre-dehydration processing conditions were optimized.Secondly,Aw and factors affecting it in the dried Tremella fuciformis product were analyzed for dehydration evaluation.Lastly,Aw was applied as a key index,as well as microwave treatment,to achieve a maximized shelf life for the reduced-sugar,instant,dried Tremella fuciformis product.Meanwhile an experimental study on the effect of Tremella fuciformis product on mice immune function was done.The results were as follows:（1）With a minimum loss of polysaccharides and the most desirable sensory quality, a combination of the pre-dehydration processing conditions was determined:soaking with pH 6 water at 30℃for 15min followed by steam cooking for 8 min under 0.1MPa.（2）With 20%polydextrose and 30%sucrose mixture a reduced（i.e.,40-45%）sugar Tremella fuciformis product with the same desirable Aw level was obtained.（3）Aw was found to be the key factor affecting the quality of the product.Salt, sugar and moisture content had marked impact on the product’s Aw in a second order f unction:Y=0.73694-0.03867X₁-0.0399X₂+0.08409X₃-0.03869X₃²（where,Y= Aw,X₁, X₂ and X₃=salt,sugar and moisture content,respectively）.（4）Aw had a significant effect on microbial growth in the dried Tremella fuciformis product.At Aw=0.645～0.721,microorganisms remained largely dormant during storage at room temperature.When Aw reached 0.763～0.813,molds and yeasts reproduced quickly causing rapid quality deterioration.（5）The killing rate on molds and yeasts in the Tremella fuciformis samples packaged in PP pouches were over 82%and 71%,respectively,after 800w microwave treatment for 120 seconds.The treated samples could be safely stored at room temperature for at least 180d.Nonetheless,the initial molds and yeasts counts should be controlled at low levels in order to receive the desired results.（6）Vacuum packing could inhibit microbial reproduction,mold growth in particular,as compared to regular packing without vacuumization.（7）The Suspension at the dose of 0.75g/kg which wan made from the Tremella fuciformis product can remarkly put up the weight of the mice organs such as thymus and spleen,and improve the amount of hemolysin.At the dose of 1.5g/kg the suspension had a significant role in improving the charcoal clearance rate,the phagocytosis of peritoneal macrophages and production of hemolysis in mice.更多还原