He Xingfen, Wang Bin, Zhao Baotang, Yang Fumin
College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China.
Foods. 2022 Mar 7;11(5):771. doi: 10.3390/foods11050771.
To extract and utilise the protein in quinoa efficiently, we investigated the effect of rate of quinoa protein isolate (QPI) extraction by ultrasound-assisted alkaline extraction and traditional alkaline extraction methods using single-factor experiments and Box-Behnken design. The effect of different heat treatment temperature and time on QPI functional properties and in vitro digestion characteristics were also investigated. The results showed that the optimal conditions of ultrasound- assisted alkaline extraction process were: ultrasonic time 99 min, solid-liquid ratio 1:20 , ultrasonic temperature 47 °C, and pH 10, and its extraction rate and purity were 74.67 ± 1.08% and 87.17 ± 0.58%, respectively. It was 10.18% and 5.49% higher than that of the alkali-soluble acid precipitation method, respectively. The isoelectric point (pI) of QPI obtained by this method was 4.5. The flexibility and turbidity of QPI had maximum values at 90 °C, 30 min, and 121 °C, 30 min, which were 0.42 and 0.94, respectively. In addition, heat treatment changed the 1.77-2.79 ppm protein characteristic region in QPI's nuclear magnetic resonance hydrogen spectroscopy (H NMR). After heating at 90 °C and 121 °C for 30 min, the hydrolysis degree and total amino acid content at the end of digestion (121 °C, 30 min) were significantly lower than those of untreated QPI by 20.64% and 27.85%. Our study provides basic data for the efficient extraction and utilisation of QPI.
为了高效提取和利用藜麦中的蛋白质，我们采用单因素实验和Box-Behnken设计，研究了超声辅助碱提取法和传统碱提取法对藜麦分离蛋白（QPI）提取率的影响。同时考察了不同热处理温度和时间对QPI功能特性及体外消化特性的影响。结果表明，超声辅助碱提取的最佳工艺条件为：超声时间99 min、固液比1:20、超声温度47℃、pH值10，其提取率和纯度分别为74.67±1.08%和87.17±0.58%，分别比碱溶酸沉法高10.18%和5.49%。该方法得到的QPI的等电点（pI）为4.5。QPI的弹性和浊度在90℃、30 min和121℃、30 min时达到最大值，分别为0.42和0.94。此外，热处理改变了QPI核磁共振氢谱（H NMR）中1.77 - 2.79 ppm的蛋白质特征区域。在90℃和121℃加热30 min后，消化结束时（121℃，30 min）的水解度和总氨基酸含量显著低于未处理的QPI，分别降低了20.64%和27.85%。我们的研究为QPI的高效提取和利用提供了基础数据。
