Wang Zhineng, Wu Guangxu, Shu Bin, Huang Fei, Dong Lihong, Zhang Ruifen, Su Dongxiao
School of Chemistry and Chemical Engineering, Guangzhou University Guangzhou 510006 P. R. China
College of Life Science, Yangtze University Jingzhou 434025 P. R. China.
RSC Adv. 2020 Feb 13;10(12):6743-6751. doi: 10.1039/c9ra08393f.
Lychee pulp is rich in phenolics and has a variety of biological activities. However, the changes in the phenolic profile under heat treatment are unknown. The effect of the heat treatment temperature on commercial varieties ( and ) of canned lychee was investigated by comparing samples that were either unheated (UH), underwent 70 °C heat treatment (HT70) or underwent 121 °C heat treatment (HT121) and then were stored at room temperature. The results showed that the total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity of the UH, HT70 and HT121 samples were significantly decreased after storage at room temperature for 9 d, 13 d and 25 d, respectively. However, the TPC, TFC and antioxidant activity of HT121 canned lychee were still significantly higher than those of the UH and HT70 samples. However, the texture characteristics of the HT121 samples were worse than those of the UH and HT70 samples, and the color of the canned lychee was darker after the HT121 treatment. Nine individual phenolic compounds were detected in the canned lychee by HPLC-DAD. The gallic acid content was increased after HT121 treatment. In particular, (-)-gallocatechin was generated by HT121 thermal processing. However, after storage at room temperature for 9 d, the contents of (-)-gallocatechin in canned and were decreased by 96.27% and 94.04%, respectively, and (-)-gallocatechin disappeared after 25 d. In summary, the phenolic contents and antioxidant activity of canned lychee are increased by high-temperature treatment.
荔枝果肉富含酚类物质，具有多种生物活性。然而，热处理后酚类物质的变化尚不清楚。通过比较未加热（UH）、经过70℃热处理（HT70）或经过121℃热处理（HT121）然后在室温下储存的罐装荔枝商业品种（和）的样品，研究了热处理温度对其的影响。结果表明，UH、HT70和HT121样品在室温下分别储存9天、13天和25天后，总酚含量（TPC）、总黄酮含量（TFC）和抗氧化活性均显著降低。然而，HT121罐装荔枝的TPC、TFC和抗氧化活性仍显著高于UH和HT70样品。然而，HT121样品的质地特性比UH和HT70样品差，HT121处理后罐装荔枝的颜色更深。通过HPLC-DAD在罐装荔枝中检测到9种单一酚类化合物。HT121处理后没食子酸含量增加。特别是，HT121热处理产生了（-）-表儿茶素。然而，在室温下储存9天后，罐装（和）中（-）-表儿茶素的含量分别下降了96.27%和94.04%，25天后（-）-表儿茶素消失。综上所述，高温处理可提高罐装荔枝的酚类含量和抗氧化活性。
