Institute of Brewing and Beverage Technology, Technical University of Munich (TUM), Freising, Germany.
J Sci Food Agric. 2019 Nov;99(14):6628-6637. doi: 10.1002/jsfa.9979. Epub 2019 Sep 9.
Many studies have confirmed a wide variation in the phenolic content and antioxidant activity of beers. However, when commercial beers are studied, there is usually no information available on the brewing technology applied. In this study, technological parameters were varied systematically to influence the antioxidant content of beer with a view to improving its flavor stability. High-throughput assays, ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) were investigated as fast analytical methods to evaluate the influence of brewing technology on antioxidant activity.
Beers (n = 12) were brewed with systematic technological variations (malt modification, hopping regime) to influence the antioxidant potential. A late hop addition resulted in significantly higher phenolic content (high-performance liquid chromatography with diode-array detection - HPLC-DAD) and antioxidant activity. Raw protein content and malt modification significantly influenced phenolic content and the antioxidant activity of beers hopped at the beginning of wort boiling. Samples were stored under forced and natural conditions and were evaluated by a sensory panel. The decline of bitter iso-α-acids as an analytical marker for oxidative aging was significantly lower in beers brewed from malts with high raw protein content. These samples also had higher antioxidant activity values. Panelists gave higher ratings for beer quality to aged beers with a late hop addition. However, late hopping resulted in enhanced hoppy aroma attributes and therefore an altered aroma profile.
Both antioxidant capacity methods were well suited as fast methods to evaluate brewing raw material and technological influence on antioxidant activity. The appropriate choice of barley malt and the malting regime could be promising tools to enhance the antioxidant activity of traditionally hopped beers. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
许多研究已经证实啤酒的酚类含量和抗氧化活性存在广泛的差异。然而，当研究商业啤酒时，通常没有关于所应用酿造技术的信息。在这项研究中，系统地改变技术参数以影响啤酒的抗氧化含量，旨在提高其风味稳定性。采用高通量测定法，即铁还原抗氧化能力（FRAP）和氧自由基吸收能力（ORAC），作为快速分析方法来评估酿造技术对抗氧化活性的影响。
通过系统的技术变化（麦芽改性、加麦阶段）酿造了 12 种啤酒，以影响其抗氧化潜力。在麦汁煮沸后期添加啤酒花可显著提高酚类含量（高效液相色谱-二极管阵列检测-HPLC-DAD）和抗氧化活性。原料蛋白质含量和麦芽改性显著影响了在麦汁煮沸初期添加啤酒花的啤酒的酚类含量和抗氧化活性。在强制和自然条件下储存样品，并通过感官小组进行评估。作为氧化老化的分析标志物，苦味异-α-酸的下降在高原料蛋白质含量的麦芽酿造的啤酒中明显较低。这些样品的抗氧化活性值也更高。品尝小组对具有后期啤酒花添加的陈酿啤酒的啤酒质量给予了更高的评价。然而，后期啤酒花添加会增强啤酒花香气特征，从而改变香气特征。
两种抗氧化能力测定方法都非常适合作为快速方法来评估酿造原料和技术对抗氧化活性的影响。选择合适的大麦麦芽和制麦工艺可能是提高传统啤酒花啤酒抗氧化活性的有前途的工具。 © 2019 作者。《食品科学杂志》由 John Wiley & Sons Ltd 代表化学工业协会出版。
