Wu Ding-Tao, Deng Wen, Li Jie, Geng Jin-Lei, Hu Yi-Chen, Zou Liang, Liu Yi, Liu Hong-Yan, Gan Ren-You
Key Laboratory of Coarse Cereal Processing (Ministry of Agriculture and Rural Affairs), Sichuan Engineering & Technology Research Center of Coarse Cereal Industralization, School of Food and Biological Engineering, Chengdu University, Chengdu 610106, China.
Research Center for Plants and Human Health, Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, National Agricultural Science and Technology Center, Chengdu 610213, China.
Antioxidants (Basel). 2023 Jul 23;12(7):1475. doi: 10.3390/antiox12071475.
Fruit thinning is a common practice employed to enhance the quality and yield of kiwifruits during the growing period, and about 30-50% of unripe kiwifruits will be thinned and discarded. In fact, these unripe kiwifruits are rich in nutrients and bioactive compounds. Nevertheless, the applications of thinned young kiwifruits and related bioactive compounds in the food and functional food industry are still limited. Therefore, to promote the potential applications of thinned young kiwifruits as value-added health products, the extraction, characterization, and evaluation of beneficial effects of phenolic compounds from thinned young fruits of red-fleshed cv 'HY' were examined in the present study. A green and efficient ultrasound-assisted deep eutectic solvent extraction (UADE) method for extracting phenolic compounds from thinned young kiwifruits was established. A maximum yield (105.37 ± 1.2 mg GAE/g DW) of total phenolics extracted from thinned young kiwifruits by UADE was obtained, which was significantly higher than those of conventional organic solvent extraction (CSE, about 14.51 ± 0.26 mg GAE/g DW) and ultrasound-assisted ethanol extraction (UAEE, about 43.85 ± 1.17 mg GAE/g DW). In addition, 29 compounds, e.g., gallic acid, chlorogenic acid, neochlorogenic acid, catechin, epicatechin, procyanidin B1, procyanidin B2, quercetin-3-rhamnoside, and quercetin-3--glucoside, were identified in the kiwifruit extract by UPLC-MS/MS. Furthermore, the contents of major phenolic compounds in different kiwifruit extracts prepared by conventional organic solvent extraction (EE), ultrasound-assisted ethanol extraction (UEE), and ultrasound-assisted deep eutectic solvent extraction (UDE) were compared by HPLC analysis. Results revealed that the content of major phenolics in UDE (about 15.067 mg/g DW) was significantly higher than that in EE (about 2.218 mg/g DW) and UEE (about 6.122 mg/g DW), suggesting that the UADE method was more efficient for extracting polyphenolics from thinned young kiwifruits. In addition, compared with EE and UEE, UDE exhibited much higher antioxidant and anti-inflammatory effects as well as inhibitory effects against α-glucosidase and pancreatic lipase, which were closely associated with its higher content of phenolic compounds. Collectively, the findings suggest that the UADE method can be applied as an efficient technique for the preparation of bioactive polyphenolics from thinned young kiwifruits, and the thinned young fruits of red-fleshed cv 'HY' have good potential to be developed and utilized as functional foods and nutraceuticals.
疏果是在猕猴桃生长期间提高果实品质和产量的常见做法，大约30%-50%的未成熟猕猴桃会被疏除并丢弃。事实上，这些未成熟的猕猴桃富含营养和生物活性化合物。然而，疏果得到的幼嫩猕猴桃及其相关生物活性化合物在食品和功能性食品工业中的应用仍然有限。因此，为了促进疏果得到的幼嫩猕猴桃作为增值健康产品的潜在应用，本研究对红肉‘HY’品种疏果得到的幼嫩果实中酚类化合物的提取、表征及其有益效果进行了评估。建立了一种绿色高效的超声辅助深共熔溶剂萃取（UADE）法从疏果得到的幼嫩猕猴桃中提取酚类化合物。通过UADE从疏果得到的幼嫩猕猴桃中提取的总酚最大产量为（105.37±1.2mg没食子酸当量/g干重），显著高于传统有机溶剂萃取（CSE，约14.51±0.26mg没食子酸当量/g干重）和超声辅助乙醇萃取（UAEE，约43.85±1.17mg没食子酸当量/g干重）。此外，通过超高效液相色谱-串联质谱（UPLC-MS/MS）在猕猴桃提取物中鉴定出29种化合物，如没食子酸、绿原酸、新绿原酸、儿茶素、表儿茶素、原花青素B1、原花青素B2、槲皮素-3-鼠李糖苷和槲皮素-3-葡萄糖苷。此外，通过高效液相色谱（HPLC）分析比较了传统有机溶剂萃取（EE）、超声辅助乙醇萃取（UEE）和超声辅助深共熔溶剂萃取（UDE）制备的不同猕猴桃提取物中主要酚类化合物的含量。结果表明，UDE中主要酚类化合物的含量（约15.067mg/g干重）显著高于EE（约2.218mg/g干重）和UEE（约6.122mg/g干重），这表明UADE法从疏果得到的幼嫩猕猴桃中提取多酚更有效。此外，与EE和UEE相比，UDE表现出更高的抗氧化和抗炎作用以及对α-葡萄糖苷酶和胰脂肪酶的抑制作用，这与其较高的酚类化合物含量密切相关。总的来说，这些发现表明UADE法可作为一种从疏果得到的幼嫩猕猴桃中制备生物活性多酚的有效技术，红肉‘HY’品种疏果得到的幼嫩果实作为功能性食品和营养保健品具有良好的开发利用潜力。
