Effect of magnetic field treatment on the softening of green chilies (Capsicum annuum L.) during storage

• Published in: Food research international 2024-11, Vol.196, p.115124, Article 115124
• Main Authors: Wei, Liwen, Wang, Jilong, zhou, Xiaohan, guo, Sijie, Zhou, Sijian, Wei, Jian, Yang, Na, Luo, Yangchao, Xu, Xueming, Jin, Yamei
• Format: Article
• Language: English
• Subjects: Capsicum - chemistry; Capsicum - radiation effects; Carboxylic Ester Hydrolases - metabolism; Cell Wall - chemistry; Cell wall metabolism; Firmness; Food Preservation - methods; Food Storage - methods; Fruit - chemistry; Fruit softening; Green chili; Magnetic field; Magnetic Fields; Pectins - chemistry; Polygalacturonase - metabolism; Refrigeration; Water - chemistry
• ISSN: 0963-9969; 1873-7145; 1873-7145
• DOI: 10.1016/j.foodres.2024.115124

[Display omitted] •Magnetic fields maintained the firmness of green chilies during storage.•Magnetic fields maintained the structures and network of pectin fractions.•Magnetic fields suppressed cell wall-modifying enzyme activities.•Magnetic fields preserved the stability and integrity of the cell wall.•Magnetic fields delayed fruit softening by modulating cell wall metabolism. In this study, effects of magnetic field treatment on the softening of green chilies during storage (0–30 d at 10 °C) were investigated, and the cell wall polysaccharide content, modifying enzyme activities, water distribution, and cell wall structure were determined. After 30 d of storage, the weight loss of the green chilies in conventional refrigeration (CR) group reached 35.40 %, whereas it was 20.96 % and 29.85 % in the static (SMF; 4 mT) and alternating magnetic field (AMF; 4 mT, 1 Hz) groups, respectively. Furthermore, magnetic field treatment maintained low levels of water-soluble pectin (WSP) and high levels of chelate-soluble pectin (CSP) and sodium carbonate-soluble pectin (NSP) in the green chilies. The degree of methylation (DE) values of WSP and NSP in the pre-treated samples were 0.37 and 0.18, respectively. Conversely, at the end of storage, the DE values of WSP and NSP in the CR, SMF, and AMF groups decreased to 0.12 and 0.05, 0.25 and 0.11, and 0.18 and 0.07, respectively, suggesting that magnetic field treatment had a negative influence on the demethylation of pectin. Magnetic field treatment also decreased the activities of pectin methyl esterase, polygalacturonase, and β-galactosidase in the green chilies, maintaining them at a low level. The magnetic field treatment resulted in a higher free water content in green chilies compared to the CR, exceeding the CR group’s content by 1.79 % and reaching 88.18 % at the terminal storage. Scanning electron microscopy results revealed that magnetic field treatment maintained the structural integrity of the cell wall in the green chilies. The results of this study confirmed the applicability of magnetic field treatment in maintaining the firmness and reducing the weight loss of the green chilies, thus prolonging their shelf life.