Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch 7602, South Africa.
SARChI Postharvest Technology Research Laboratory, Faculty of AgriSciences, Africa Institute for Postharvest Technology, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa.
Molecules. 2022 May 6;27(9):2979. doi: 10.3390/molecules27092979.
Hot water blanching at 80 °C for 3 min can be used as a novel pre-treatment step in pomegranate peel to preserve the integrity of the phytochemical content within the peel extracts by lowering or inactivating enzymes such as polyphenol (PPO) oxidase and peroxidase (POD) that are responsible for the break-down of phytochemicals within the peel. The aim of this study was to investigate the effect of hot water blanching pre-treatment on yield, bioactive compounds, antioxidants, enzyme inactivation, and antibacterial activity of ‘Wonderful’, ‘Acco’, and ‘Herskawitz’ pomegranate peel extracts. We used a variety of spectrophotometric-based assays and liquid chromatography mass spectrometry (LC-MS)-based approach to characterize and quantify metabolites within the peel extracts. Blanching significantly (p < 0.05) reduced PPO activity in all peel extracts, with the highest PPO reduction in ‘Herskawitz’ peel extracts at 0.25 U/mL. Furthermore, higher antioxidant activity in ‘Herskawitz’ blanched peel extracts using 2,2-diphenyl-1-picryl hydrazyl (DPPH) antioxidant activity, ferric ion reducing antioxidant power (FRAP), and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity at 567.78 ± 9.47 µmol Trolox/g DM, 800.05 ± 1.60 µmol Trolox/g DM, and 915.27 ± 0.61 µmol Trolox/g DM, respectively, was noted. ‘Herskawitz’ blanched peel extracts were recorded with the lowest minimum inhibitory concentration (MIC) value of 80 µg/mL for Gram-positive Bacillus subtilis and Gram-negative Klebsiella pneumoniae bacteria strains. A total of 30 metabolites were present in ‘Acco’ and ‘Herskawitz’ peel extracts and were tentatively identified after LC-MS profiling. This study demonstrates that blanched peel extracts from ‘Herskawitz’ cultivar have great potential for commercial use in value-added products in the nutraceutical, cosmeceutical, and pharmacological industries.
80°C 热水烫漂 3 分钟可作为石榴皮的一种新型预处理步骤，通过降低或失活负责皮内植物化学物质分解的多酚（PPO）氧化酶和过氧化物酶（POD）等酶，来保持皮内植物化学物质的完整性。本研究旨在探讨热水烫漂预处理对‘ Wonderful’、‘Acco’和‘Herskawitz’石榴皮提取物的产率、生物活性化合物、抗氧化剂、酶失活和抗菌活性的影响。我们使用各种分光光度法测定和液相色谱-质谱（LC-MS）法来表征和定量皮内提取物中的代谢物。烫漂显著（p<0.05）降低了所有皮提取物中的 PPO 活性，其中‘Herskawitz’皮提取物中的 PPO 降低幅度最大，为 0.25 U/mL。此外，用 2,2-二苯基-1-苦基肼（DPPH）抗氧化活性、铁还原抗氧化能力（FRAP）和 2,2-偶氮-双（3-乙基苯并噻唑啉-6-磺酸（ABTS）自由基清除活性测定，‘Herskawitz’烫漂皮提取物的抗氧化活性更高，分别为 567.78±9.47 µmol Trolox/g DM、800.05±1.60 µmol Trolox/g DM 和 915.27±0.61 µmol Trolox/g DM。‘Herskawitz’烫漂皮提取物对革兰氏阳性枯草芽孢杆菌和革兰氏阴性肺炎克雷伯菌的最低最小抑菌浓度（MIC）值分别为 80µg/mL 和 160µg/mL。在‘Acco’和‘Herskawitz’皮提取物中存在 30 种代谢物，并通过 LC-MS 分析进行了初步鉴定。本研究表明，‘Herskawitz’品种的烫漂皮提取物具有在营养保健品、化妆品和药理学行业的高附加值产品中商业应用的巨大潜力。
