Abstract Malt soluble protein (SP) can be determined by different analytical procedures such as Kjeldahl, combustion, or spectrophotometry. From a practical standpoint, the spectrophotometric method is the most preferred. This method requires a linear calibration with different malts in a wide SP range. For this calibration however, protein in wort is determined by Kjeldahl as the reference method. Considering that some soluble protein standards could be used as an alternative for the Kjeldahl analysis in the calibration step, the objective of this research was to evaluate the use of bovine serum albumin (BSA) as a protein standard in the determination of SP. Results showed that the BSA standard curve overestimates protein in wort and, therefore, SP values. However, estimated vs. actual wort protein values were highly associated (R2=0.9984) and the correspondent regression lines had similar slopes. Taking this into account, the BSA standard curve was adjusted with wort protein values observed in international malt check samples (SP range= 4.3–6.4% of malt, dry basis). The resultant equation from the BSA adjusted curve [wort protein, %wt/vol= (1.4007* A215-225) − 0.0071] improved the estimation of protein in wort by minimizing differences in magnitude.

中文翻译：

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牛血清白蛋白在分光光度法测定原麦汁中蛋白质的应用

摘要 麦芽可溶性蛋白 (SP) 可以通过不同的分析程序进行测定，例如凯氏定氮法、燃烧法或分光光度法。从实用的角度来看，分光光度法是最优选的。这种方法需要在很宽的 SP 范围内使用不同的麦芽进行线性校准。然而，对于此校准，麦汁中的蛋白质由凯氏定氮法作为参考方法测定。考虑到某些可溶性蛋白质标准品可用作校准步骤中凯氏定氮分析的替代品，本研究的目的是评估使用牛血清白蛋白 (BSA) 作为蛋白质标准品在 SP 测定中的应用。结果表明，BSA 标准曲线高估了麦芽汁中的蛋白质，因此高估了 SP 值。然而，估计值与实际麦汁蛋白值高度相关（R2=0。9984）和相应的回归线具有相似的斜率。考虑到这一点，BSA 标准曲线根据在国际麦芽检查样品中观察到的麦芽汁蛋白值进行了调整（SP 范围=麦芽的 4.3-6.4%，干基）。来自 BSA 调整曲线的结果方程 [麦芽汁蛋白质，%wt/vol= (1.4007* A215-225) - 0.0071] 通过最小化量级差异改进了对麦芽汁中蛋白质的估计。