Purpose

Solid-state fermentation (SSF) has been highlighted as an alternative to obtain valuable compounds using agro-industrial wastes as a substrate. The present study evaluated the impact of extrusion combined with SSF on the production of phenolic compounds and their antioxidant activity using pecan nut shell (PWS) as a substrate.

Design/methodology/approach

PWS and extruded pecan nut shell (PWSE) were fermented for 120 h at 30°C using Aspergillus oryzae (A. oryzae). Samples were withdrawn from incubator at 6 h, 12 h and then every 12 h until 120 h fermentation. PWS and PWSE samples were extracted. The total phenolic content (TPC) and radical scavenging activity (RSA) extracts were characterized from the resulting extracts.

Findings

The use of PWSE yielded higher A. oryzae biomass and at a higher rate after 120 h of fermentation (PWS 75.74% vs PWSE 87.50%). In general, the TPC and the RSA increased with fermentation time. However, the PWSE yielded significantly higher (p < 0.05) TPC and RSA values after SSF in comparison to the nonextruded PWS. Condensed tannins showed different trends depending on the fermented substrate. Overall, results showed that the extrusion pretreatment joint with the SSF represents a good alternative to raise the phenolic content and antiradical activity of lignocellulosic materials such as PWSs.

Originality/value

This study offers valuable information that may be used by the pecan walnut industry to valorize the shell coproduct as a substrate to produce functional ingredients or fungal enzymes.

中文翻译：

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米曲霉挤压固相发酵对山核桃壳酚类化合物及自由基清除活性的影响

目的

固态发酵 (SSF) 已被强调为使用农业工业废物作为基质获得有价值化合物的替代方法。本研究使用山核桃壳 (PWS) 作为底物，评估了挤压与 SSF 相结合对酚类化合物生产及其抗氧化活性的影响。

设计/方法/方法

使用米曲霉（A.oryzae）将PWS和挤压山核桃壳（PWSE）在30°C下发酵120小时。在 6 小时、12 小时和然后每 12 小时从培养箱中取出样品，直到发酵 120 小时。提取 PWS 和 PWSE 样品。从所得提取物中表征总酚含量 (TPC) 和自由基清除活性 (RSA) 提取物。

发现

PWSE 的使用在发酵 120 小时后产生更高的米曲霉生物量和更高的速率（PWS 75.74% vs PWSE 87.50%）。一般而言，TPC 和 RSA 随发酵时间增加。然而，与非 挤压 PWS 相比，SSF 后PWSE 产生显着更高的TPC 和 RSA 值（p < 0.05）。取决于发酵底物，缩合单宁表现出不同的趋势。总体而言，结果表明，带有 SSF 的挤出预处理接头是提高木质纤维素材料（如 PWS）的酚类含量和抗自由基活性的良好替代方案。

原创性/价值

这项研究提供了有价值的信息，山核桃核桃工业可能会使用这些信息将壳副产品作为生产功能成分或真菌酶的底物进行评估。