【作者】 吴新；

【导师】 郑永华；

【作者基本信息】 南京农业大学 ， 食品科学， 2010， 硕士

【摘要】 草莓和杨梅都属于浆果类,以其果色鲜艳,营养丰富,酸甜可口而受到大众的喜爱。但草莓和杨梅都无外皮保护,组织娇嫩,含水量高,极易受到机械损伤和微生物的侵染而发生腐败变质。目前,草莓和杨梅等浆果类最常用的贮藏方法是冷藏结合化学保鲜剂处理,但是化学保鲜剂的长期和大量使用会产生抗药性、食品安全以及环境污染等问题。因此,寻找安全有效的保鲜技术非常必要。本文以“丰香”草莓和“乌种”杨梅为试材,研究了香芹酚、肉桂醛、紫苏醛、沉香萜醇和异硫氰酸烯丙酯(AITC)等五种植物精油对草莓和杨梅果实的保鲜效果及适宜浓度,并从抗氧化、抗病及体外抑菌作用等几个方面进行机理的探讨,以期为植物精油在草莓和杨梅等浆果类果实保鲜中的应用提供依据。主要研究结果如下：(1)五种植物精油都能显著抑制果实腐烂指数和失重率的上升,保持较高的果实硬度、可溶性固形物和Vc含量,在贮藏后期,还能抑制总糖和还原糖含量的下降。但处理浓度过高会产生药害,AITC和紫苏醛对草莓果实的处理浓度达到5μL/L时就产生药害,其它3种精油在10μL/L时也产生药害,并且杨梅果实耐药性高于草莓果实。草莓果实保鲜的适宜浓度为：AITC-1μL/L、紫苏醛-1μL/L、肉桂醛-1μL/L、香芹酚-5μL/L、沉香萜醇-5μL/L；杨梅果实保鲜的适宜浓度为：AITC-20μL/L、香芹酚-1μL/L、肉桂醛-0.5μL/L、沉香萜醇-1μL/L、紫苏醛-1μL/L。(2)香芹酚、肉桂醛、紫苏醛和沉香萜醇处理能显著提高草莓和杨梅果实总酚、总黄酮、总花青素和酚类单体等抗氧化相关物质的含量,保持较高的SOD、POD、APX和CAT等抗氧化相关酶活性,抑制自由基清除率和还原力的下降。AITC处理果实的结果则相反,果实的抗氧化能力显著低于对照,而超氧阴离子含量显著高于对照。这些结果表明,香芹酚、肉桂醛、紫苏醛和陈香萜醇等4种精油减少腐烂的原因可能是通过提高果实的抗氧化能力,增强自由基清除能力,延缓果实衰老。而AITC精油则可能是通过超氧阴离子的积累,对病原菌产生直接的过氧化作用。(3)香芹酚、肉桂醛、紫苏醛和沉香萜醇能够显著提高草莓和杨梅果实的PAL、POD、丁质酶和p-1,3葡聚糖酶等抗病相关酶活性,提高果实抗病性。AITC处理组的PAL等酶活性则一直显著低于对照组。大部分体内实验的最佳浓度在体外实验中都有一定的抑菌效果,随着精油浓度的升高,抑制率升高,孢子萌发率降低,芽管长度减小,其中AITC效果最好。所以,结合第三章的研究结果,香芹酚、肉桂醛、紫苏醛和沉香萜醇等四种精油减少果实腐烂,可能是提高果实抗氧化能力和抗病相关酶活性以及直接抑菌作用三方面协同作用的结果；而AITC减少果实腐烂可能与通过过氧化作用直接抑制病菌的生长有关。更多还原

【Abstract】 Strawberry and bayberry are all berries and they are very popular with consumers for their special moderate sweet and sour taste, rich in nutritions and bright and attractive color. Non-epicarp and high water content of flesh exposed to the atmosphere is susceptible to mechanical injury, physiological deterioration, water loss and microbiological decay. Botrytis cinerea is the major postharvest fungal disease on strawberries and Verticicladiella abietina (Peck) Hughes is the main postharvest fungal disease on Chinese bayberries. At present, refrigerated method combined with synthetic chemical fungicides are most commonly used method of storage for strawberries and Chinese bayberries, but the synthetic chemical fungicides have many problems such as food safety, resistance of chemicals and environmental pollution with long-term and heavy use. Therefore, the search for a safe and effective alternative to chemical fungicides or a part replacement is very important. In this paper, freshly harvested strawberries (Fragaria ananassa Duch. Cv. Fengxiang) and Chinese bayberries(Myrica rubra sieb.et Zucc. Cv. Wumei) were used to study the preservation effect of five essential oils, carvacrol, cinnamaldehyde, perillaldehyde, linalool and allyl isothiocyanate. Then, we investigated the mechanism from the anti-oxidation, fruit disease resistance and the effect of antifungal aspects to provide the theoretical basis for preservation of berries. The results were as follows:1 In the selected experiments, all five plant essential oils had significant effect on the storage of strawberries and Chinese bayberries. Decay index and weight loss rate were significantly inhibited by all five plant essential oils. High fruit firmness was maintained, The TSS, Vc content and other quality parameters were not adversely affected, the decrease of total sugar and reducing sugar content were also inhibited late in storage. However, high concentrations caused injury, injury emerged on strawberry fruit only with 5μL/L AITC and perillaldehyde treatments and 10μL/L in the other three kinds of essential oils treatments. Furthermore, the resistance of essential oils for Chinese bayberry fruits were higher than the strawberry fruits. The suitable experimental concentration on strawberry fruits were as follows:AITC-1μL/L, perillaldehyde-1μL/L, cinnamaldehyde-1μL/L, carvacrol-5μL/L and linalool-5μL/L; The suitable experimental concentration on Chinese bayberry fruits were as follows:AITC-20μL/L, carvacrol-1μL/L, cinnamaldehyde-0.5μL/L, linalool-1μL/L and perillaldehyde-1μL/L.2 Significant effects on antioxidant systems of postharvest strawberry and Chinese bayberry fruits were determined in other four kinds of essential oil treatments except AITC treatment, including an increase of antioxidant related substances total phenolics, total flavonoids, total anthocyanins, phenolic monomers content, and the activity of antioxidant-related enzymes SOD, POD, APX, CAT. The mechanism for these four essential oils to reduce fruit decay may be related to the improving of antioxidant activity to enhance free radical scavenging capacity and delay senescence. AITC treatment had the opposite effect in antioxidant capacity, the antioxidant capacity was significantly lower than control group, but O2- production was significantly higher. Therefore, the mechanism of AITC to inhibit fruit rot of strawberries and Chinese bayberries may be a kind of "pro-oxidant" effect to inhibit the growth of fungi directly.3 Carvacrol, cinnamaldehyde, perillaldehyde and linalool could significantly improve the activities of disease resistance related enzymes PAL, POD, chitinase andβ-1,3 glucanase in strawberry and Chinese bayberry fruits. The activity of PAL, POD, chitinase andβ-1,3 glucanase in AITC treatments were significantly lower than the control group. Most of the suitable concentration in vivo experiments had some kind of antifungal effect in vitro too. As the oil concentration increased, the inhibition rate increased, spore germination and germ tube length decreased, and the AITC treatment had the best antifungal activity. Therefore, combining the findings of the third chapter, carvacrol, cinnamaldehyde, perillaldehyde and linalool may through the synergy effect of enhancing fruit antioxidant capacity, improving fruit disease resistance and direct antifungal effect. AITC may through the pro-oxidant effect to inhibit the growth of fungi directly to reduce the decay of berries.更多还原