【作者】 陈晨；

【导师】 郑永华；

【作者基本信息】 南京农业大学 ， 食品工程， 2015， 硕士

【摘要】 胡萝卜是清脆可口、营养丰富的家常菜。在市场消费过程中,直接鲜食的胡萝卜商品附加值低,可以对胡萝卜进行切分、加工等处理,形成方便食品。鲜切胡萝卜拥有天然、卫生、新鲜以及环保等特征,拥有广阔的市场前景。但胡萝卜经过去皮、切分等加工过程,整体的代谢协调性受到破坏,诱发一系列生理生化反应。在贮藏、运输及销售过程中,其品质的变化与完整保存的胡萝卜有所差别。短波紫外线(UV-C)当前被普遍应用于食品领域、医疗卫生范畴、水处理行业及一些工业范畴的消毒杀菌,具有无毒无害、高效无残留等优点。在鲜切果蔬贮藏过程中使用UV-C处理,可以有效杀灭微生物。相关研究表明,短波紫外处理还有利于果蔬贮藏过程中的营养品质的保持,提高果蔬的抗氧化能力。因此,本文主要研究了UV-C处理对鲜切胡萝卜在贮藏期间营养品质的影响,并从次生代谢、抗氧化能力及活性氧代谢相关酶等方面进行探讨研究,为UV-C处理在鲜切胡萝卜贮藏保鲜中的应用提供理论依据。研究结果如下:(1)鲜切处理导致胡萝卜白度值上升、微生物繁殖速度加快,但同时也促进了胡萝卜中总酚含量、总胡萝卜素含量的上升,提高DPPH自由基清除率、ABTS~+自由基清除率以及羟基自由基抑制率,从而提高抗氧化能力。其中,切丝处理的样品中,总酚、总胡萝卜素含量上升最多,抗氧化能力也最强。(2)UV-C处理对鲜切胡萝卜贮藏期间白度值的变化没有影响,但对胡萝卜表面的微生物具有明显的杀菌作用。较低剂量的0.21kJ/m~2和0.42kJ/m~2的UV-C处理,总酚与总胡萝卜素的增加量不如0.86 kJ/m2处理的效果好。较高剂量1.68kJ/m~2的UV-C处理,总胡萝卜素含量在贮藏后期低于对照,表明过高的UV-C处理剂量对其品质的保持产生了负作用。因此,总结出0.86 kJ/m~2的UV-C处理对鲜切胡萝卜丝品质的保持作用最好,有效的促进了总酚、总胡萝卜素含量的上升,延缓了维生素C含量的下降。(3)0.86 kJ/m~2的UV-C有利于鲜切胡萝卜丝贮藏过程中总酚、总胡萝卜素含量的上升,抑制维生素C含量的下降。胡萝卜中含量最多的酚类单体为绿原酸、咖啡酸,是胡萝卜的次生代谢产物。实验结果表明,UV-C处理显著提高了 PAL、C4H、4-CL的活性,促进胡萝卜丝的次生代谢作用,从而有利于鲜切胡萝卜贮藏过程中绿原酸、咖啡酸含量上升,并且表现出总酚含量的上升。0.86 kJ/m~2的UY-C处理可以使鲜切胡萝卜丝在贮藏过程中保持较高的SOD、POD、CAT和APX活性,进一步提高DPPH自由基清除率和ABTS~+自由基清除率,延缓羟基自由基抑制率的下降,抑制超氧阴离子的生成,从而进一步提高鲜切胡萝卜丝的抗氧化能力。更多还原

【Abstract】 Carrot is a kind of homemade vegetables which is delicious and rich of nutrient.In the consumption process of the market,the commodity added value of direct fresh carrot is very low.We can syncopate and process carrot in order to form convenient food.Fresh-cut carrot is Natural,health,fresh and green,so it has wide market prospect.Through the process of peel,cut and so on,the overall metabolic coordination of carrot is destroyed,which can cause a series of physiological and biochemical reactions.During the process of storage,transportation and sale,the changes of quality of carrots are different from other carrots which are well preserved.At present,UV-C treatment is widely used in Sterilizing ultraviolet radiation such as medical and health,food,water treatment and other industrial fields.It has advantages of high efficiency,harmless and no residues.The use of radiation in fresh-cut fruits and vegetables during storage processing,can effectively kill microorganisms,and will not damage the color,smell,taste,hardness and other sensory quality of fruits and vegetables,easier to be accepted by consumers.Research shows that,the UV-C treatment of fruits and vegetables is beneficial to the nutritional quality of fruits and vegetables to maintain and it can improve the antioxidant ability during storage.In these paper,I study the effects and mechanism of UV-C treatment on quality maintenance and antioxidant capacity in fresh-cut carrot,in order to provide theoretical underpinning for the preservation of fresh-cut carrot.The main results were as follows:(1)Segmentation treatment improved the whiteness value and the speed of microbial propagation in fresh-cut carrot during storage,but also increase the total phenolic content and the total carotenoid content,increase DPPH radical scavenging activity,ABTS~+ radical scavenging activity and hydroxyl radical scavenging.Shred processing is the best method,can most increase the content of total phenolic content,the total carotenoid content and oxidation resistance.(2)UV-C treatment had no effect on the change of white value of fresh-cut carrot during storage,but it had marked bactericidal effect on the microorganism on carrot surface.0.86 kJ/m~2 UV-C treatment effect on the quality of fresh-cut carrot are best kept,effectively promote the total phenolic content,the increase of the content of total carrot,delayed the decrease of Vc content.UV-C treatment group with the low dose of 0.21kJ/Dm~2 and 0.42kJ/m~2,the increase of total phenolic content and total carotene content is lower than the 0.86 kJ/m~2 treatment.UV-C treatment group with the high dose of 1.68kJ/m~2,the total carotene content higher than that of the control group in the first and second days,but on the third day and the fourth day,it is lower than that of the control group,high dose UV-C treatment showed the negat:ive effect to maintain the quality.(3)Compared with the control group,0.86 kJ/m~2 UV-C treatment increased the total phenol,the total carotene content and inhibited the decrease of vitamin C content during storage.Chlorogenic acid and Coffee acid are secondary metabolites of carrot.UV-C treatment significantly increased PAL,C4H,4-CL activity,secondary metabolism promote carrots,which benefits the increase of fresh cut carrots during storage of chlorogenic acid,Coffee acid content,and showed a rise in the total phenols content 0.86 kJ/m~2 UV-C treatment can keep higher SOD,POD,CAT and APX activity during the storage of fresh-cut carrot,further improve the DPPH radical scavenging rate and ABTS~+ free radical scavenging rate,delay the decrease of hydroxyl radical inhibition rate,inhibit the generation of superoxide anion,thereby further improving the antioxidant capacity of fresh-cut carrot.更多还原