Pinto Gabriella, De Pascale Sabrina, Aponte Maria, Scaloni Andrea, Addeo Francesco, Caira Simonetta
Department of Chemical Sciences, University of Naples "Federico II", via Cintia, 80126 Naples, Italy.
Proteomics & Mass Spectrometry Laboratory, ISPAAM, National Research Council, via Argine 1085, 80147 Naples, Italy.
Molecules. 2021 Apr 17;26(8):2335. doi: 10.3390/molecules26082335.
Plant polyphenols have beneficial antioxidant effects on human health; practices aimed at preserving their content in foods and/or reusing food by-products are encouraged. The impact of the traditional practice of the water curing procedure of chestnuts, which prevents insect/mould damage during storage, was studied to assess the release of polyphenols from the fruit. Metabolites extracted from pericarp and integument tissues or released in the medium from the water curing process were analyzed by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) and electrospray-quadrupole-time of flight-mass spectrometry (ESI-qTOF-MS). This identified: (i) condensed and hydrolyzable tannins made of (epi)catechin (procyanidins) and acid ellagic units in pericarp tissues; (ii) polyphenols made of gallocatechin and catechin units condensed with gallate (prodelphinidins) in integument counterparts; (iii) metabolites resembling those reported above in the wastewater from the chestnut curing process. Comparative experiments were also performed on aqueous media recovered from fruits treated with processes involving: (i) tap water; (ii) tap water containing an antifungal strain; (iii) wastewater from a previous curing treatment. These analyses indicated that the former treatment determines a 6-7-fold higher release of polyphenols in the curing water with respect to the other ones. This event has a negative impact on the luster of treated fruits but qualifies the corresponding wastes as a source of antioxidants. Such a phenomenon does not occur in wastewater from the other curing processes, where the release of polyphenols was reduced, thus preserving the chestnut's appearance. Polyphenol profiling measurements demonstrated that bacterial presence in water hampered the release of pericarp metabolites. This study provides a rationale to traditional processing practices on fruit appearance and qualifies the corresponding wastes as a source of bioactive compounds for other nutraceutical applications.
植物多酚对人体健康具有有益的抗氧化作用；鼓励采取措施来保留食品中多酚的含量和/或重新利用食品副产品。研究了栗子水固化程序这一传统做法的影响，该做法可防止栗子在储存期间受到昆虫/霉菌损害，以评估果实中多酚的释放情况。通过基质辅助激光解吸电离飞行时间质谱（MALDI-TOF-MS）和电喷雾四极杆飞行时间质谱（ESI-qTOF-MS）分析了从果皮和种皮组织中提取的代谢物或在水固化过程中释放到介质中的代谢物。结果确定：（i）果皮组织中由（表）儿茶素（原花青素）和酸性鞣花单元组成的缩合单宁和水解单宁；（ii）种皮对应物中由没食子儿茶素和儿茶素单元与没食子酸盐缩合而成的多酚（原翠雀素）；（iii）栗子固化过程废水中与上述类似的代谢物。还对从经过以下处理的果实中回收的水介质进行了对比实验：（i）自来水；（ii）含有抗真菌菌株的自来水；（iii）先前固化处理产生的废水。这些分析表明，前一种处理方式使固化水中多酚的释放量比其他处理方式高6至7倍。这一情况对处理过的果实的光泽有负面影响，但使相应的废物成为抗氧化剂的来源。在其他固化过程的废水中不会出现这种现象，在这些废水中多酚的释放量减少，从而保持了栗子的外观。多酚谱测量表明，水中的细菌会阻碍果皮代谢物的释放。这项研究为传统水果加工做法对果实外观的影响提供了理论依据，并使相应的废物成为其他营养保健应用中生物活性化合物的来源。
