BACKGROUND Soursop (Annona muricata L.) is an underutilized tropical and subtropical fruit with high nutritional and therapeutic benefits. This fruit is faced with enormous post-harvest losses due to its high perishability. This work was aimed to optimize the pectinase-assisted extraction conditions of soursop juice using Doehlert design and to study the effect of pectinase on its pectin structure. RESULTS The predicted models were validated for all the responses studied and the regression coefficients ranged from 0.905 to 0.987 (p ≤ 0.05). An incubation time of 172 min, enzyme concentration of 0.04% (w/w) and incubation temperature at 42.9 °C were found to be the optimal conditions for soursop juice extraction, which resulted in 75.20%, 3.74, 87.06%T, 7.35 °Brix, and 0.44% MAE for soursop juice yield, pH, clarity, TSS, and titratable acidity respectively. Morphologically, untreated soursop pulp presented a non-uniform spherical surface; enzyme hydrolyzed soursop exhibited ruptured and wrinkled surface; meanwhile for the different pectin obtained, untreated soursop pectin depicted porous surface and enzyme hydrolyzed soursop pectin showed whirling rough surface. FTIR confirmed the presence of similar chemical group stretching and vibrations in commercial pectin and soursop pectin. CONCLUSION Under the optimum conditions, the numerical predictions were similar to the experimental data obtained, thus confirming the validity of the models. Application of enzyme treatment caused the breakdown of pectin structure as illustrated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analyses. This article is protected by copyright. All rights reserved.

中文翻译：

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番荔枝汁果胶酶辅助提取工艺优化及液化对其果胶结构的影响

背景刺果番荔枝（Annona muricata L.）是一种未充分利用的热带和亚热带水果，具有很高的营养和治疗效果。由于其高度易腐烂，这种水果面临着巨大的收获后损失。本工作旨在利用 Doehlert 设计优化果胶酶辅助提取刺果番荔枝汁的条件，并研究果胶酶对其果胶结构的影响。结果 预测模型针对所有研究的响应进行了验证，回归系数的范围为 0.905 至 0.987 (p ≤ 0.05)。发现 172 分钟的孵育时间、0.04% (w/w) 的酶浓度和 42.9 °C 的孵育温度是刺果番荔枝汁提取的最佳条件，得到 75.20%、3.74、87.06%T、7.35°白利糖度和 0.44% MAE 用于 soursop 汁产量、pH、澄清度、TSS、和可滴定酸度。从形态上看，未经处理的刺果番荔枝果肉呈现出不均匀的球形表面；酶水解刺果番荔枝表面破裂和起皱；同时对于获得的不同果胶，未经处理的刺果果胶呈现多孔表面，酶水解刺果果胶呈现旋转的粗糙表面。FTIR 证实了商业果胶和刺果果胶中存在类似的化学基团拉伸和振动。结论在最佳条件下，数值预测与获得的实验数据相似，从而证实了模型的有效性。如扫描电子显微镜 (SEM) 和傅里叶变换红外光谱 (FTIR) 分析所示，酶处理的应用导致果胶结构的破坏。本文受版权保护。