Guo Mengmeng, Du Jinhua, Zhang Kaili, Jin Yuhong
College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, 271018, China.
J Sci Food Agric. 2014 Oct;94(13):2794-800. doi: 10.1002/jsfa.6631. Epub 2014 Mar 25.
Arabinoxylans (AXs) are partially water-extractable polymers that cause problems of viscosity and filterability during beer brewing. This study investigated the effects of Kolbach index (KI) on water-extractable AXs (WEAXs).
KI had positive correlations with extract (r = 0.845) and free amino nitrogen (FAN) (r = 0.958). The contents of malt WEAXs (WEAXsm), total AXs and wort AXs (WAXs) were 10.8-11.6 g kg⁻¹, 57.5-60.8 g kg⁻¹ and 137.5-140.5 mg per 100 mL respectively and the corresponding arabinose/xylose (A/X) ratios were 0.52-0.56, 0.55-0.62 and 0.48-0.50. The molecular weight (Mw) ranged from 4.92 × 10⁴ to 6.93 × 10⁴ Da for WEAXsm and from 1.24 × 10⁴ to 2.90 × 10⁴ Da for WAXs. KI had negative correlations with the average degree of polymerization (avDP) of malt (r = -0.877) and wort (r = -0.978). Wort viscosity showed a positive correlation with the Mw of WEAXsm (Mwm) (r = 0.821).
Increasing KI can promote the degradation of the xylan backbone, while it cannot affect the branching of the polymer chain and the content and Mw of WEAXs.
阿拉伯木聚糖（AXs）是部分可水提取的聚合物，在啤酒酿造过程中会导致粘度和过滤性问题。本研究调查了库尔巴赫指数（KI）对水可提取AXs（WEAXs）的影响。
KI与浸出物（r = 0.845）和游离氨基氮（FAN）（r = 0.958）呈正相关。麦芽WEAXs（WEAXsm）、总AXs和麦芽汁AXs（WAXs）的含量分别为10.8 - 11.6 g kg⁻¹、57.5 - 60.8 g kg⁻¹和每100 mL 137.5 - 140.5 mg，相应的阿拉伯糖/木糖（A/X）比值分别为0.52 - 0.56、0.55 - 0.62和0.48 - 0.50。WEAXsm的分子量（Mw）范围为4.92×10⁴至6.93×10⁴ Da，WAXs的分子量范围为1.24×10⁴至2.90×10⁴ Da。KI与麦芽（r = -0.877）和麦芽汁（r = -0.978）的平均聚合度（avDP）呈负相关。麦芽汁粘度与WEAXsm的Mw（Mwm）呈正相关（r = 0.821）。
提高KI可促进木聚糖主链的降解，但不影响聚合物链的分支以及WEAXs的含量和Mw。
