This study aimed to develop agar extraction protocols for Gracilaria salicornia from Tanzania and investigate its physico‐chemical characteristics. A 33 factorial experimental design was used in the extraction of agar whereby three independent variables of NaOH concentration (10, 20 and 30% w/v), alkali pre‐treatment duration (0.5, 1 and 2 h) and extraction temperatures (115, 120 and 125°C) were used to determine the optimum conditions for production of high‐quality agar. Agar yield, gel strength, sulfate content, gelling and melting temperatures were evaluated as dependent variables. The optimal condition was observed at 30% NaOH concentration, 2 h alkali pre‐treatment duration and 120°C extraction temperature. The yield, gel strength, sulfate content, gelling and melting temperatures of the agar obtained under these conditions were 26.9 ± 0.7%, 510.3 ± 16.2 g cm−2, 0.29 ± 0.04%, 39.3°C and 88.4°C, respectively. These properties are very close to that of imported commercial agar. It was concluded that the local agar is capable of replacing imported agar for most general purposes. This offers a new possibility of using quality local agar in place of commercial agar.

中文翻译：

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坦桑尼亚当地海藻Gracilaria salicornia琼脂提取工艺的优化

本研究旨在为来自坦桑尼亚的江蓠草制定琼脂提取方案并研究其理化特性。在琼脂提取中使用了 33 因子实验设计，其中 NaOH 浓度（10、20 和 30% w/v）、碱预处理持续时间（0.5、1 和 2 小时）和提取温度（115， 120 和 125°C) 用于确定生产优质琼脂的最佳条件。琼脂产量、凝胶强度、硫酸盐含量、胶凝和熔化温度被评估为因变量。在 30% NaOH 浓度、2 h 碱预处理时间和 120°C 提取温度下观察到最佳条件。在这些条件下获得的琼脂的产率、凝胶强度、硫酸盐含量、胶凝和熔化温度为 26.9±0.7%，分别为 510.3 ± 16.2 g cm-2、0.29 ± 0.04%、39.3°C 和 88.4°C。这些特性与进口商品琼脂非常接近。结论是本地琼脂能够代替进口琼脂用于大多数一般用途。这提供了使用优质当地琼脂代替商业琼脂的新可能性。