Dept. of Food Science and Technology, Virginia Polytechnic Inst. and State Univ., 360 Duck Pond Dr., Blacksburg, VA, 24061, USA.
Dept. of Biochemistry, Virginia Polytechnic Inst. and State Univ., 111 Engel Hall, Blacksburg, VA, 24061, USA.
J Food Sci. 2019 Aug;84(8):2147-2158. doi: 10.1111/1750-3841.14713. Epub 2019 Jul 17.
Multiple analytical methods are used for quantification of total polyphenols and total flavanols in fruit juices and beverages. Four methods were evaluated in this study: Folin-Ciocalteu (F-C), Lowenthal permanganate (L-P), 4-dimethylaminocinnamaldehyde (DMAC), and the bovine serum albumin (BSA) precipitation method. Method validation parameters, including working range, limit of detection, limit of quantitation, precision (repeatability), accuracy, and specificity, were assessed and compared. The F-C method was not specific to polyphenols, and the L-P method had the widest working range but lacked accuracy. The DMAC method was the most specific to flavanols, and the BSA method was not suitable for quantification of smaller flavanols, such as catechin and epicatechin. Quantitative performance was evaluated using commercial fruit juice samples (n = 14), apple juice samples of different cultivars (n = 22), and commercial ciders (n = 17). In general, the L-P titration method and DMAC method resulted in higher quantitative values than the F-C method and BSA precipitation method, respectively. However, ratios of results obtained by the L-P and F-C method ranged from 1 to 28, and ratios of results obtained by the DMAC and BSA precipitation method ranged from <1 to 280. This tremendous variation is likely due to variation in polyphenol composition and sample matrix. This information provides perspective for comparison of results obtained through these different methods, and a basis for choosing the most appropriate analytical method for quantification of polyphenols to address a specific research question when working with commercial fruit juice, apple juice from different apple cultivars, and commercial ciders. PRACTICAL APPLICATION: This study compared results obtained when four common polyphenol quantification methods were applied to a diverse selection of fruit juices and beverages with distinct polyphenol composition and sample matrix. The matrix and polyphenol composition of the samples significantly influenced the results. Our findings can help manufacturers of fruit-based products choose the most appropriate analytical method for polyphenol quantification as part of a quality assurance program or to convey information on dietary polyphenol content to consumers. An assessment of analytical method validation parameters is provided for each of the four methods, which will help users of these methods to understand their limitations.
用于定量测定果汁和饮料中总多酚和总黄烷醇的分析方法有多种。本研究评估了四种方法：福林-考克法（F-C）、Lowenthal 高锰酸盐法（L-P）、4-二甲氨基肉桂醛（DMAC）和牛血清白蛋白（BSA）沉淀法。评估和比较了方法验证参数，包括工作范围、检测限、定量限、精密度（重复性）、准确度和特异性。F-C 法对多酚的特异性不强，而 L-P 法的工作范围最宽，但准确度不足。DMAC 法对黄烷醇最具特异性，而 BSA 法不适合定量较小的黄烷醇，如儿茶素和表儿茶素。使用商业果汁样品（n=14）、不同品种的苹果汁样品（n=22）和商业苹果酒（n=17）评估定量性能。总体而言，L-P 滴定法和 DMAC 法的定量值分别高于 F-C 法和 BSA 沉淀法。然而，L-P 和 F-C 法的结果比值范围为 1 至 28，DMAC 和 BSA 沉淀法的结果比值范围为 <1 至 280。这种巨大的差异可能是由于多酚组成和样品基质的变化。这些信息为比较这些不同方法获得的结果提供了视角，并为解决使用商业果汁、不同苹果品种的苹果汁和商业苹果酒时的具体研究问题而选择最适合的分析方法定量测定多酚提供了依据。实际应用：本研究比较了四种常见多酚定量方法应用于具有不同多酚组成和样品基质的多种果汁和饮料时获得的结果。样品的基质和多酚组成显著影响结果。我们的研究结果可以帮助水果制品制造商选择最适合的多酚定量分析方法，作为质量保证计划的一部分，或向消费者传达关于饮食中多酚含量的信息。提供了对这四种方法的每个方法的分析方法验证参数评估，这将帮助这些方法的用户了解其局限性。
