Abstract

The lignocellulosic residue cassava peel is an unexplored source of bioactive compounds, such as hemicellulose-based xylooligosaccharides (XOS) that present prebiotic properties. In this sense, this work aimed to produce XOS from cassava peels that were pretreated with NaOH (xylan extraction and lignin removal) followed by enzymatic hydrolysis (endo-1–4-β-xylanase). The cassava peels were pretreated sequentially: starch removal, alkaline hydrolysis, and enzymatic hydrolysis. The aqueous-mechanical reduction and sieving for 15 cycles removed ≈16% of starch (iodometric method). The alkaline pretreatments were carried out with 2, 4, and 6% (w/v) NaOH, 1:100/solid:liquid at 121 °C and 1.1 bar for 30 or 60 min. The enzymatic kinetics was evaluated with enzyme concentration at 0.5, 1.5, and 3.0% (v/v). The highest alkaline hydrolysis reached 34.20% of lignin removal (2% (w/v) NaOH for 30 min). The highest XOS yield was 396.5 mg XOS/g xylan after 48 h and 3.0% enzyme concentration. Regarding the mass balance, from 300 g of cassava peels (an agroindustrial residue), it is possible to obtain up to 3.27% XOS. Therefore, the fractionation of hemicellulose from cassava peels was technically viable from the concepts of biorefinery and bioeconomy, being one of the first researches to approach the extraction of xylan from cassava peel to obtain XOS through an enzymatic route with a highly promising yield.

Highlights

• The high starch content is a drawback to producing cassava peel-based xylooligosaccharides.

• Delignification and extraction of xylan from cassava peels by alkaline hydrolysis were performed.

• Xylooligosaccharides were produced by enzymatic hydrolysis with endo-1–4-β-xylanase.

• The highest yield of cassava peel-based xylooligosaccharides, already reported.

Graphical abstract

中文翻译：

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使用长臂木霉的 endo-1,4-β-xylanase 生产木薯皮基低聚木糖：碱性预处理的效果

摘要

木质纤维素残渣木薯皮是生物活性化合物的未开发来源，例如具有益生元特性的基于半纤维素的低聚木糖 (XOS)。从这个意义上说，这项工作旨在从木薯皮中生产 XOS，木薯皮经过 NaOH（木聚糖提取和木质素去除）预处理，然后进行酶水解（endo-1-4-β-xylanase）。木薯皮依次进行预处理：去淀粉、碱解和酶解。15 个循环的水-机械还原和筛分去除了约 16% 的淀粉（碘量法）。碱性预处理用 2、4 和 6% (w/v) NaOH，1:100/固体:液体在 121 °C 和 1.1 bar 下进行 30 或 60 分钟。在酶浓度为 0.5、1.5 和 3.0% (v/v) 时评估酶动力学。碱性水解最高达到34。去除 20% 的木质素（2% (w/v) NaOH 30 分钟）。在 48 小时和 3.0% 的酶浓度后，最高 XOS 产量为 396.5 mg XOS/g 木聚糖。关于质量平衡，从 300 克木薯皮（一种农工业残渣）中，可以获得高达 3.27% 的 XOS。因此，从生物精炼和生物经济的概念来看，从木薯皮中分离半纤维素在技术上是可行的，是最早通过酶促途径从木薯皮中提取木聚糖以获得 XOS 的研究之一，具有很高的收率。

强调

• 高淀粉含量是生产木薯皮基低聚木糖的一个缺点。

• 进行了通过碱解从木薯皮中脱木质素和提取木聚糖。

• 低聚木糖是通过用endo-1–4-β-xylanase 酶水解产生的。

• 木薯皮基低聚木糖产量最高，据报道。

图形概要