Papadaki Eirini S, Palaiogiannis Dimitrios, Lalas Stavros I, Mitlianga Paraskevi, Makris Dimitris P
Laboratory of Food Chemistry and Technology, Department of Chemical Engineering, University of Western Macedonia, ZEP Campus, 50100 Kozani, Greece.
Green Processes & Biorefinery Group, Department of Food Science & Nutrition, School of Agricultural Sciences, University of Thessaly, N. Temponera Street, 43100 Karditsa, Greece.
Antioxidants (Basel). 2022 Dec 14;11(12):2457. doi: 10.3390/antiox11122457.
Wheat bran (WB) is globally a major food industry waste, with a high prospect as a bioresource in the production of precious polyphenolic phytochemicals. In this framework, the current investigation had as objectives (i) to use ethanol organosolv treatment and study the effect of acid and alkali catalysts on releasing bound polyphenols, (ii) establish linear and quadratic models of polyphenol recovery based on severity and response surface, and (iii) examine the polyphenolic composition of the extracts generated. Using sulfuric acid and sodium hydroxide as the acid and the alkali catalyst, respectively, it was found that the correlation of combined severity factor with total polyphenol yield was significant in the acid catalysis, but a highly significant correlation in the alkali-catalyzed process was established with modified severity factor, which takes into consideration catalyst concentration, instead of pH. Optimization of the process with response surface confirmed that polyphenol release from WB was linked to treatment time, but also catalyst concentration. Under optimized conditions, the acid- and alkali-catalyzed processes afforded total polyphenol yields of 10.93 ± 0.62 and 19.76 ± 0.76 mg ferulic acid equivalents g dry mass, respectively. Examination of the polyphenolic composition revealed that the alkali-catalyzed process had a striking effect on releasing ferulic acid, but the acid catalysis was insufficient in this regard. The outcome concerning the antioxidant properties was contradictory with respect to the antiradical activity and ferric-reducing power of the extracts, a fact most probably attributed to extract constituents other than ferulic acid. The process modeling proposed herein may be valuable in assessing both process effectiveness and severity, with a perspective of establishing WB treatments that would provide maximum polyphenol recovery with minimum harshness and cost.
麦麸（WB）在全球范围内是主要的食品工业废弃物，作为生产珍贵多酚类植物化学物质的生物资源具有很高的前景。在此框架下，当前的研究目标包括：（i）使用乙醇有机溶剂处理并研究酸碱催化剂对释放结合态多酚的影响；（ii）基于反应强度和响应面建立多酚回收率的线性和二次模型；（iii）检测所生成提取物的多酚组成。分别使用硫酸和氢氧化钠作为酸碱催化剂，发现在酸催化中，综合反应强度因子与总多酚产率的相关性显著，但在碱催化过程中，与考虑催化剂浓度而非pH值的修正反应强度因子建立了高度显著的相关性。用响应面法对工艺进行优化证实，WB中多酚的释放与处理时间以及催化剂浓度有关。在优化条件下，酸碱催化过程的总多酚产率分别为10.93±0.62和19.76±0.76毫克阿魏酸当量/克干物质。对多酚组成的检测表明，碱催化过程对阿魏酸的释放有显著影响，但在这方面酸催化不足。关于抗氧化性能的结果在提取物的抗自由基活性和铁还原能力方面相互矛盾，这很可能归因于除阿魏酸之外的提取物成分。本文提出的工艺建模对于评估工艺有效性和反应强度可能具有重要价值，有望建立能以最小的苛刻条件和成本实现最大多酚回收率的WB处理方法。
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