【作者】 李铁华；

【导师】 张慜；

【作者基本信息】 江南大学 ， 食品科学， 2007， 博士

【摘要】 茶树菇（Agrocybe chaxingu）是一种近年来新开发的极有价值的食用菌,常温下极易腐烂,贮藏非常困难,目前对其研究主要集中在栽培种植技术和功能因子方面,贮藏保鲜方面的研究较少。本文以茶树菇为研究对象,采用硅窗气调包装（MAPW）技术进行贮藏,保鲜效果显著,延长茶树菇的保鲜期达到20d以上。为了更好地保鲜贮藏茶树菇,探讨了茶树菇采后贮藏过程中的生理生化特性的变化,分析这些变化对茶树菇贮藏品质的影响,为贮藏方法的选择和贮藏工艺条件的确定提供理论依据。在实验中,探明了茶树菇能忍受的O₂浓度最低值是1.1%,低于这一最低值将发生厌氧呼吸。在试验的几种贮藏方法中,MAPW包装贮藏的茶树菇品质最好,贮藏期最长,也没有化学污染,是一种贮藏茶树菇的较好方法。为了提高MAPW贮藏的保鲜效果,选择了对茶树菇贮藏过程中生理特性影响比较大的3个因素:贮藏的初始气体组成、包装盒的硅窗面积及贮藏温度进行分析研究,分别探讨这些因素的变化对茶树菇贮藏过程中的气体环境、营养生理及感官品质等指标的影响。在这些研究的基础上,以抗坏血酸保留率及感官评定得分为响应值,设计3因素3水平的响应面分析,获得了MAPW贮藏茶树菇的最佳工艺参数,它们分别是:初始气体组成为5%O₂和10%CO₂;包装盒的硅窗面积为0.9cm2;贮藏温度为3℃。MAPW贮藏的茶树菇比对照（普通气调包装）的呼吸强度低,呼吸基质消耗少,其总糖含量相对较高;MAPW贮藏的茶树菇的粗纤维含量增加相对缓慢,贮藏20d,其粗纤维增加量只有对照的62.8%;MAPW贮藏的茶树菇的蛋白质含量、总氨基酸含量仅有少量下降,游离氨基酸含量也只有少量上升,说明其蛋白质代谢基本处于平衡状态;光镜和电镜解剖分析发现,随着贮藏时间的延长,MAPW贮藏的茶树菇的显微结构和超微结构比对照样品变化缓慢,网状结构保持时间长;菌肉和菌髓丝状细胞的中空结构能大部分得到保持,分布的均匀性和有序排列基本不会被破坏。MAPW与普通气调包装贮藏比,硅窗良好的透气性能保证了包装盒内与周围环境的气体交换,及时排除了茶树菇在贮藏过程中产生的乙烯气体,避免了高浓度乙烯环境中蛋白质的水解,使细胞膜得到保护,细胞膜系统的完整性更好。同时,MAPW贮藏的茶树菇自由基清除酶类的活性明显高于对照,能更有效地清除体内的自由基,使其自由基的产生与淬灭机制较长时间保持平衡,贮藏的茶树菇少受自由基的伤害,延长了其贮藏期。通过分析和比较MAPW包装盒内O₂和CO₂浓度变化规律,选择了酶动力学模型来描述茶树菇贮藏过程中的呼吸速率特性,求出了模型参数,得出了在3℃和7℃时MAPW贮藏茶树菇的呼吸模型;对实测值与模型预测值进行验证表明,模型有比较好的应用效果。更多还原

【Abstract】 Agrocybe chaxingu is a newly developed valuable edible mushroom. It is rotten easily at ambient temperature, and difficult to store. So far the study on the mushroom is mainly focus on the cultivate technology and its functional factors. Not much research on the preservation of Agrocybe chaxingu has been reported. In this study,MAP with silicon gum film window（MAPW）was used to store Agrocybe chaxingu, and the effects were obviously, which prolonged the shelf life of Agrocybe chaxingu to more than 20 days.The changes of physiological characteristics during storage were discussed, and the effect of these changes to the storage quality of Agrocybe chaxingu was analyzed in this paper, which provides a theoretical basis for the selection of storage method and determination of storage conditions. It was found from the experiments that the the lowest limit of O₂ concentration for storing Agrocybe chaxingu was 1.1%, and the anaerobic respiration would occur if the O₂ concentration was lower than the minimum value. Among these storage methods, the quality of Agrocybe chaxingu stored by MAPW was the best, with longest storage period and no chemical pollution. It is a good method for Agrocybe chaxingu storage.In order to improve the storage effect of MAPW, 3 factors （initial gas composition, silicon gum film window area of packaging and storage temperature） which strongly affect the physiological characteristics during storage were selected as the study objects. The effects of these factors on the gas environment of the packages, loss rate of Ascorbic acid, titratable acidity, changing of soluble solids, increasing rate of cell membrane permeability and decreasing of sensory quality during Agrocybe chaxingu storage period were explored. On the basis of these study, Ascorbic acid retention and sensory evaluation scores were set as response value, 3-factor and 3-level of response surface analysis was designed. The best parameters of MAPW for Agrocybe chaxingu storing were acquired: initial gas compositions were 5%O₂ and 10%CO₂, silicon window area of packing was 0.9cm2 and the storage temperature was 3℃.Taking conventional MAP as control, the effect of MAPW storage on the quality of Agrocybe chaxingu was studied. The Agrocybe chaxingu stored by MAPW had low respiration rate, low respiratory substrate consumption, so the total sugar content kept a relatively high level; cellulose enzyme of Agrocybe chaxingu stored by MAPW had higher activity, the increase of coarse fiber content was relatively slow. The coarse fiber increases was 62.8% that of control after 20d storage. During the whole storage period, the protein content and total amino acids content only decline a little, and free amino acids content increased a small amount either. These indicated that the protein metabolism was basically in a equilibrium state; It was found by light microscope and electronic microscope analysis that the microstructure and ultrastructure of Agrocybe chaxingu stored by MAPW changed slower than that of the control. The network structure could keep a relatively long time; Most of the hollow structure of the thread-like cell of fugai could be maintained, the uniform distribution and orderly arrangement were basically not destroyed.Compared with conventional MAP storage, high permeability of the silicon gum film window ensured the exchange of gas in the packing with surrounding atmosphere. Ethylene gas generated during the Agrocybe chaxingu storage could be exhausted in time, avoiding the hydrolysis of protein in high concentration Ethylene gas environment, cell membrane could be protected, thus the membrane system was more integrity. The activity of free radical scavenging enzymes of MAPW stored Agrocybe chaxingu was apparently higher than that of control. It could scavenge the free radical more effectively, so the generation and extinction mechanism of free radical could keep balance for a longer period, decreasing the hurt from free radical, the storage period of Agrocybe chaxingu could be extended. By analyzing and comparing the change rules of O₂ and CO₂ concentration in the MAP packing, enzymes Kinetic Model was selected to descript the characteristics of respiration rate during Agrocybe chaxingu storage. The model parameters are calculated. The respiration models at 3 and 7℃for MAPW stored Agrocybe chaxingu were acquired; Comparison of the experiment value and calculated value showed that the models have good application effect.更多还原