Vhangani Lusani Norah, Van Wyk Jessy
Department of Food Science and Technology, Cape Peninsula University of Technology, Bellville 7535, South Africa.
Foods. 2023 Feb 1;12(3):602. doi: 10.3390/foods12030602.
Green rooibos' bioactive compounds contribute greatly towards its antioxidant activity. The anti-browning activity of aqueous (GRE) and beta-cyclodextrin (β-GRE)-assisted extracts of green rooibos was investigated in canned apples. Freeze-dried extracts (GRE and β-GRE) obtained at 40 °C for 60 min were added in canned apples at 0.25 and 0.5% prior to heat processing and stored at 23 and 37 °C for 24 weeks. Lightness (L*), colour difference (DE*), furfural and hydroxymethyl furfural (HMF) were determined to establish the effect of extracts against non-enzymatic browning (NEB) development. The L* value decreased, whereas DE*, HMF and furfural increased with increased storage time and temperature. A higher inhibition was observed for samples stored at 23 °C, and storage at 37 °C reduced ( < 0.05) the inhibitory capacity of extracts. Greater inhibition against NEB development was reported for β-GRE 0.25 and 0.5 via the L* value (40.93-46.67%), β-GRE 0.25 for DE* (46.67%) and β-GRE 0.25 and 0.5 for HMF (59.55-67.33%). No differences ( > 0.05) were observed in furfural inhibition between all extracts, although inhibition was reported at 62.69-72.29%. Browning inhibition correlated with the reaction rate constant (k) and activation energy (Ea), exhibiting a correlation coefficient of 0.925, 0.964, 0.932 and 0.754 for L*, DE*, HMF and furfural, respectively.
绿茶提取物的生物活性化合物对其抗氧化活性有很大贡献。研究了绿茶水提取物（GRE）和β-环糊精辅助提取物（β-GRE）在罐装苹果中的抗褐变活性。在40℃下干燥60分钟得到的冻干提取物（GRE和β-GRE），在热处理前以0.25%和0.5%的比例添加到罐装苹果中，并在23℃和37℃下储存24周。通过测定亮度（L*）、色差（DE*）、糠醛和羟甲基糠醛（HMF）来确定提取物对非酶促褐变（NEB）发展的影响。随着储存时间和温度的增加，L值降低，而DE、HMF和糠醛增加。在23℃下储存的样品观察到更高的抑制作用，而在37℃下储存会降低（<0.05）提取物的抑制能力。通过L值（40.93-46.67%），报告了β-GRE 0.25和0.5对NEB发展的更大抑制作用，β-GRE 0.25对DE*（46.67%）以及β-GRE 0.25和0.5对HMF（59.55-67.33%）的抑制作用。尽管所有提取物对糠醛的抑制率在62.69-72.29%之间，但在糠醛抑制方面未观察到差异（>0.05）。褐变抑制与反应速率常数（k）和活化能（Ea）相关，L、DE*、HMF和糠醛的相关系数分别为0.925、0.964、0.932和0.754。
