【作者】 段颖；

【导师】 顾振新；

【作者基本信息】 南京农业大学 ， 食品科学， 2005， 硕士

【摘要】 珍稀食用菌—茶薪菇富含蛋白质、多糖和多种微量元素,具有较高的营养价值和保健作用。近年来,茶薪菇栽培在我国较为普遍。由于茶薪菇组织柔嫩,含水量高,受机械损伤后极易引起微生物的侵入,造成软烂和腐臭等。此外,茶薪菇采收后还会出现菇柄伸长、开伞等现象,外界环境条件不利时这些变化加剧,导致茶薪菇降低商品价值,甚至失去商品价值。控制环境条件,延长茶薪菇采后货架寿命,保持其营养价值,增加其利用价值,是亟待解决的问题。本文以茶薪菇为试材,筛选了适宜的贮藏品种和成熟度,研究了不同保鲜方法对茶薪菇贮藏特性的影响。 1、比较研究了不同品种、不同采收期的茶薪菇贮藏特性。结果表明:在（15±1）℃温度下贮藏,白色和棕色两种茶薪菇失重率相近。棕色品种的呼吸强度、电导率、褐变度和可溶性蛋白质含量变化小于白色品种。早采的茶薪菇其失重率最大,中期采收的茶薪菇呼吸强度最大,晚采的茶薪菇电导率变化最大。茶薪菇在5℃下贮藏其呼吸强度、褐变度、可溶性蛋白质含量最低,其次是10℃下贮藏的茶薪菇。可见,茶薪菇棕色品种比白色品种耐藏;中期采收的棕色茶薪菇适合贮藏;低温有利于茶薪菇贮藏。 2、进行了以L-Cys、EDTA-2Na、PA和CA为护色剂的茶薪菇保鲜研究。结果表明,用浓度分别为2.5,0.5,1.0和3.0 mg·ml^-1的L-Cys、EDTA-2Na、PA和CA组成的复合保鲜剂处理的茶薪菇在（10±1）℃下可保存6d,贮藏期间不开伞,气味正常,褐变度和呼吸强度明显低于对照。 用O₃处理棕色和白色茶薪菇0.5min后在（15±1）℃下进行的贮藏试验结果表明,棕色茶薪菇比白色耐藏,棕色茶薪菇用O₃处理0.5～2min后在（20±1）℃下贮藏7d后,开伞率为3%,褐变程度轻。 包装袋打孔处理对茶薪菇保鲜效果影响的研究结果表明,茶薪菇在（15±1）℃温度下贮藏,包装袋打孔处理可明显降低呼吸强度,减少还原糖消耗,保护膜结构完整,延长了茶薪菇保藏期。 3、研究了PPO的酶学性质。结果表明:PPO反应产物的最大吸收波长为410nm,最适底物为L-Tyr;PPO在30℃以下较稳定,50℃时酶活力达到高峰;茶薪菇PPO的最适反应pH为4.6,并且在pH5.0和pH8.0时较稳定;茶薪菇棕色品种有2种同工酶,白色品种没有同工酶,但白色品种的PPO活力较高。L-Cys和AA对PPO活性的抑制率最高。更多还原

【Abstract】 Agrocybeaegerita, a rare edible fungus, is rich in proteins, polysaccharides and mineral substances and has high nutrition value and healthy function for human body. However, because of its tender structure, high water content, it is easy to suffer from mechanical injury, and then microorganisms find the way to invade and cause it deterioration. Besides, if Agrocybeaegerita would be stored at normal temperature for a short time after harvesting, its stem would prolong and umbrella be open. Environmental conditions such as oxygen, high humidity and temperature could aggravate those changes, which could low and loss its commercial value. How to control environmental conditions, prolong shelf-life of Agrocybeaegerita and hold its nutritional value is a problem that will be settled urgently. In this dissertation, two varieties of Agrocybeaegerita were taken as experimental material. Their storage properties and effects of different fresh keeping technologies on their storage qualities were studied. The main research content and corresponding results were summarized as follows.1. Comparative analysis of the storage properties between white and brown variety of Agrocybeaegerita at different harvest period was carried out. It was concluded that at 15±1 °C, weight loss of white variety was similar to brown one. But the respiration rate, relative electric conductance, browning degree of and soluble protein in brown variety were lower than that of white one. It was obvious that brown variety was more tolerant for storage than white one. Weight loss of two varieties harvested at early stage was highest. Respiration rate of two varieties harvested at middle stage was highest, the other indices were lowest. And the change of relative electric conductance of two varieties harvested at late stage was biggest. It suggested that brown variety harvested at middle stage was suitable for storage. The indices mentioned above of two varieties stored at 5℃ were lower than that at 10 ℃. It was indicated that Agrocybeaegerita was favorite for low temperature environmental condition.2. Effect of color protection agents, viz. L-cys, EDTA-2Na, PA and CA on Agrocybeaegerita quality were observed. The results showed that the optimum combination of color protection agents was 2.5 mg·ml^-1 L-cys, 0.5 mg·ml^-1 EDTA-2Na, 1.0 mg·ml^-1 PAand 3.0 mg·ml^-1 CA. With this complex treatment, the shelf life of brown variety could reach six days at the temperature of 10 ±1℃, and its umbrella was not open, smell good, browning degree and respiration were significantly lower than that of CK.Brown and white varieties, treaded with O₃ for 30 s, and then were stored at 15±1 ℃. The results showed Brown variety was more tolerant for store than white one Brown one, treaded with O₃ for 30s to 2min, and then was stored at 20±1 ℃, after seven days, there was 3 % of brown Agrocybeaegerita umbrella open and its browning degree was small.Effect of PE film package with different number holes（Φ0.6 mm） on the storage quality of Agrocybeaegerita at 15±1℃ was studied. It was indicated that the PE film package with a number of hole could significantly reduce the respiration and consumption of reducing sugar of Agrocybeaegerita and its cell membrane integration was protected. Thereby, the shelf life of Agrocybeaegerita was prolonged.3. Enzymatic properties of PPO in Agrocybeaegerita was studied. It was concluded that the maximum absorbent wavelength of reaction product catalyzed by PPO was 410 nm. Optimum substrate catalyzed by PPO was L-Tyr. PPO was stable at 30℃. Optimum reaction temperature was 50℃. It was stable at pH 5.0 or 8.0. Optimum pH was 4.6 and 8.0. PPO activity in Agrocybeaegerita could be strongly inhibited by L-cys and ascorbic acid, the brown variety had two isoenzymes. White one had no isoenzymes, but had higher activity.更多还原