壳聚糖涂膜对鲜切哈密瓜品质、抗氧化能力和微生物污染的影响

发布时间：2018-06-23 07:37

本文选题：壳聚糖 + 鲜切　；参考：《甘肃农业大学》2017年硕士论文

【摘要】：哈密瓜为西北地区特色水果,但果实的可食率仅为60%左右。由于哈密瓜产区和销地距离偏远,物流成本很高,因此有必要开发新的维持采后品质,降低物流成本的保鲜技术。本试验以“西州蜜”哈密瓜为食材,果实切割后用2%的壳聚糖处理,装入保鲜盒,定期测定处理对鲜切果实品质、抗氧化能力和微生物污染的影响。结果表明:1.壳聚糖涂膜有效降低了鲜切果实的失重率,维持了硬度,第12 d时,处理组失重率低于对照组24.1%,硬度高于对照组13.3%。壳聚糖涂膜还有效维持了果块的色泽,以及TSS和TA含量,第12 d时,处理组L*值、a*值和b*值分别高于对照组4.3%、24.3%和13.3%,TSS含量高于对照组6.9%,TA含量低于对照组35.2%。2.壳聚糖涂膜有效维持了鲜切果块贮藏期间的感官品质。第9 d时,处理组在口感、香气和腐烂指标方面均显著优于对照组,瓜块无腐烂,品质与初采时的果实接近。第12d时,虽然处理组色泽、口感、香气以及腐烂得分高于对照组,但瓜块开始腐烂,品质明显降低,不具食用价值。故9 d和6 d分别为处理组和对照组的最长保质期。3.壳聚糖涂膜有效推迟鲜切果块的H_2O_2出现高峰,降低了H_2O_2含量,处理提高了贮藏期间果实Vc、总酚和类黄酮含量,第12 d时,分别高于对照组18.1%、28.9%和83.1%。涂膜提高了超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性;抑制了抗坏血酸过氧化物酶(APX)、过氧化物酶(POD)和多酚氧化酶(PPO)的活性。处理组还提高了果块对DPPH.自由基和ABTS.+自由基的清除能力,第9 d时,分别高出对照组41.5%和51.9%。4.壳聚糖涂膜显著抑制果块表面菌落总数、酵母菌、霉菌、大肠菌群数的增长,对照组上述4项指标在贮藏6 d后均快速增加,而处理组在9 d后才开始缓慢增加,第12 d时,处理组菌落总数、酵母菌、霉菌和大肠菌群数量分别仅为对照组的1/5、1/9、1/5和1/6。在整个冷藏期间,对照组和处理组中均未检出沙门氏菌、金黄色葡萄球菌和李斯特菌。综上所述,壳聚糖涂膜可最大程度的保持“西州蜜”哈密瓜果块的品质,显著提高了果块的抗氧化能力,抑制了果块表面的菌落总数、酵母菌、霉菌、大肠菌群数的增长。综合感官评价结果表明,壳聚糖处理后可使鲜切哈密瓜的保质期延长3 d。
[Abstract]:Hami melon is a characteristic fruit in Northwest China, but its edible rate is only about 60%. Because of the remote distance between the area of Hami melon production and sale, the logistics cost is very high, so it is necessary to develop a new fresh-keeping technology to maintain postharvest quality and reduce logistics cost. In this experiment, "Xizhou Honey" Hami melon was used as the food material, the fruit was treated with 2% chitosan after cutting, and the effect of the treatment on the quality, antioxidant ability and microbial contamination of fresh-cut fruit was determined periodically. The result shows that 1: 1. Chitosan coating could effectively reduce the weight loss rate of fresh-cut fruit and maintain the hardness. At the 12th day, the weight loss rate of the treatment group was lower than that of the control group (24.1g), and the hardness was higher than that of the control group (13.3%). Chitosan film also effectively maintained the color of fruit block, TSS and TA content. At the 12th day, the content of TSS in treatment group was higher than that in control group (4.33%, 24.3%) and higher than that in control group (13.3%). The content of TSS in treatment group was lower than that in control group (35.22.2.The content of TSS in treated group was higher than that in control group (P < 0.05). Chitosan film can effectively maintain the sensory quality of fresh cut fruit during storage. On the 9th day, the taste, aroma and decay index of the treatment group were significantly better than that of the control group, and the fruit quality of the treatment group was similar to that of the fruit at the first harvest. On the 12th day, although the color, taste, aroma and rotting score of the treatment group were higher than that of the control group, the gourd began to rot, and the quality decreased obviously, and had no edible value. Therefore, 9 d and 6 d were the longest shelf life of treatment group and control group respectively. Chitosan coating could effectively delay the peak of H _ 2O _ 2 in fresh cut fruit, decrease the content of H _ 2O _ 2, increase the contents of Vc, total phenol and flavonoid in fruit during storage, and on the 12th day, it was higher than that of the control group by 28.9% and 83.1%, respectively. The superoxide dismutase (SOD) and catalase (cat) activities were increased, and the activities of ascorbic acid peroxidase (APX), peroxidase (POD) and polyphenol oxidase (PPO) were inhibited. The treatment group also increased the fruit block pair DPPH. Free radicals and ABTS. The scavenging ability of free radicals was 41.5% and 51.9% higher than that of the control group on the 9th day, respectively. Chitosan coating significantly inhibited the increase of the total number of colony, yeast, mold and coliform bacteria on the surface of fruit block. In the control group, the above four indexes increased rapidly after 6 days of storage, but the treatment group began to increase slowly after 9 days, and at the 12th day. The total number of colonies, yeast, mold and coliform in the treatment group were only 1 / 5 / 1 / 9 / 5 and 1 / 6 of the control group, respectively. Salmonella, Staphylococcus aureus and Listeria were not detected in control group and treatment group during cold storage. To sum up, chitosan film can maintain the quality of "Xizhou honey" fruit block of Hami melon, improve the antioxidant ability of fruit block, and inhibit the increase of the total number of colony, yeast, mold and coliform group on the surface of fruit block. The results of sensory evaluation showed that the shelf life of fresh-cut Hami melon could be prolonged by 3 days after chitosan treatment.
【学位授予单位】：甘肃农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TS255.3

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