Application of a chitosan coating as a carrier for natamycin to maintain the storage quality of ground cherry (Physalis pubescens L.)

Abstract

Ground cherry (Physalis pubescens L.) is a kind of berry fruit favored by consumers in China; however, this fruit is particularly vulnerable to physiological senescence and pathogen attack during the traditional cold storage period. In order to maintain storage quality, a 1.5% (w/w) chitosan (CS) water solution containing 50 mg/L of natamycin (NA) was introduced. After all treatments were completed, the fruit was stored at 0 °C and sampled every 10 d. At each sampling date, the following tests were performed: mold and yeast analyses; enzyme activity and content analyses which included superoxide dismutase (SOD), ascorbate peroxidase (APX), and malondialdehyde (MDA); and color analysis. In addition, a sensory evaluation was carried out for quality assessment at the end of the storage period. The results showed that the application of a chitosan coating combined with natamycin (CSNA) enhanced the activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX), reduced the physiological rate of senescence, and inhibited pathogen attack. Thus, CSNA treatment can maintain ground cherries at an acceptable level of storage quality for 50 d.

中文概要

目的

通过壳聚糖和那他霉素在果蔬生理代谢和致病微 生物抑制等方面的特点,达到减缓毛酸浆果实在 贮藏期间的生理衰老和抑制致病菌发展,进而提 高毛酸浆贮藏品质。

创新点

壳聚糖作为一种涂被剂,可以均匀地分布在果蔬 表面。许多学者在研究中发现壳聚糖可以延缓果 蔬的生理代谢。那他霉素作为一种真菌抑制剂, 通常和涂被剂联合用于奶酪的贮藏防霉。本文的 创新在于壳聚糖和那他霉素联合在毛酸浆贮藏 中的应用。

方法

按比例制备出壳聚糖水溶液,随后定量添加那他 霉素并搅拌均匀。毛酸浆果实在浸泡一定时间 后,捞出沥干。随后按照实验设计进行分组处理。 在贮藏期内,定期测定菌落总数对数值、果实外 部色差、超氧化物歧化酶(SOD)和抗坏血酸过 氧化物酶(APX)酶活性、丙二醛(MAD)含量 及感官评价等指标。最后进行总结分析。

结论

单独使用壳聚糖时,可以延缓毛酸浆果实的生理 衰老,但是难以抑制贮藏期间的致病微生物(主 要是真菌类);作为一种真菌抑制剂,那他霉素 具有水溶性低的特点,难以单独使用。那他霉素 与壳聚糖联合使用时,壳聚糖即可对毛酸浆果实 起到生理作用,还可以作为那他霉素的载体,使 其均匀分布在果实表面。二者联合使用既能延缓 毛酸浆果实的生理衰老,又能抑制贮藏期间的致 病菌,从而达到提高毛酸浆贮藏品质的目的。