Zheng Meixia, Zhang Chong, Zhou Ying, Lu Zhaoxin, Zhao Haizen, Bie Xiaomei, Lu Fengxia
Laboratory of Enzyme Engineering, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, China.
Front Microbiol. 2018 Aug 3;9:1729. doi: 10.3389/fmicb.2018.01729. eCollection 2018.
To improve the antibacterial and antioxidant properties of chitosan (CS), CS grafted with gallic acid (GA) using recombinant bacterial laccase from fmb-103 (fmb-rL103) as a catalyst. The structures of grafted chitosans were identified using Fourier transform infrared spectroscopy (FT-IR) and UV visible spectrum (UV-Vis spectroscopy). After gallic acid grafting, the antibacterial properties of chitosans against , , , , , , and were significantly improved. Meanwhile, 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging results showed that the antioxidant properties of grafted CS increased as well. The preservative effects of the grafted chitosan on chilled meat were then investigated. For this purpose, the quality indexes of the chilled meat during the storage were monitored, including total bacterial count, total basic volatile nitrogen (TVB-N) content, pH value, color and thiobarbituric acid reactive substances (TBARS) and so on. The results showed that coating with the grafted chitosan retarded the growth of spoilage bacteria, and decreased TVB-N and TBARS values of meat. The shelf life of chilled meat coated by CS grafted with GA (GA-g-CS) also extended from 6 days to 18 days at 4°C. These results provided a theoretical basis for the future application of the GA-g-CS in the preservation of chilled meat. (1)The temperature and pH-stable bacterial laccase was used to synthesize gallic acid grafted chitosan.(2)Antioxidant and antibacterial properties of chitosan were improved through grafting gallic acid.(3)Storage properties of chilled meat were improved by coating with gallic acid grafted chitosan.
为提高壳聚糖（CS）的抗菌和抗氧化性能，以来源于fmb - 103的重组细菌漆酶（fmb - rL103）为催化剂，制备了接枝没食子酸（GA）的壳聚糖。采用傅里叶变换红外光谱（FT - IR）和紫外可见光谱（UV - Vis光谱）对接枝壳聚糖的结构进行了表征。没食子酸接枝后，壳聚糖对金黄色葡萄球菌、大肠杆菌、枯草芽孢杆菌、沙门氏菌、李斯特菌、肉毒杆菌和蜡样芽孢杆菌的抗菌性能显著提高。同时，1,1 - 二苯基 - 2 - 苦基肼（DPPH）自由基清除实验结果表明，接枝壳聚糖的抗氧化性能也有所增强。随后研究了接枝壳聚糖对冷却肉的保鲜效果。为此，监测了冷却肉在贮藏期间的质量指标，包括细菌总数、总挥发性盐基氮（TVB - N）含量、pH值、色泽和硫代巴比妥酸反应物（TBARS）等。结果表明，用接枝壳聚糖涂膜可抑制腐败菌的生长，降低肉中的TVB - N和TBARS值。在4℃下，GA接枝壳聚糖（GA - g - CS）涂膜的冷却肉货架期也从6天延长至18天。这些结果为GA - g - CS在冷却肉保鲜中的应用提供了理论依据。（1）利用温度和pH稳定的细菌漆酶合成没食子酸接枝壳聚糖。（2）通过接枝没食子酸提高壳聚糖的抗氧化和抗菌性能。（3）用没食子酸接枝壳聚糖涂膜改善冷却肉的贮藏性能。
