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.

Personal response systems, such as clickers, have been widely used to improve the effectiveness of teaching in various classroom settings. Although hand-held clicker response systems have been the subject of multiple prior studies, few studies have focused on the use of cell phone-based personal response system (CPPRS) specifically. This study explores students' academic performance and their perceptions of learning through the use of a CPPRS (TopHat) in an undergraduate Food Science class. In this study, students did not use the CPPRS during the first half of the semester-long course, but did during the second half. When CPPRS was used, students responded to 2 multiple-choice questions at 3 points during the class, (a) at the beginning of class, (b) in the middle of the class, and (c) at the end of the class. Student performance was measured by correctness rates on eight 10-item multiple choice quizzes, 4 quizzes each covering the class content that was delivered with compared with without CPPRS. A survey was conducted at the end of the semester asking (n = 28) students' perceptions of CPPRS. The average correctness rate for quizzes covering content delivered with CPPRS (85% ± 9%) was significantly higher than for content delivered without CPPRS (82% ± 10%) (P = 0.016). In addition, students perceived that CPPRS was easy to use (5.04 ± 0.58 on a 1 to 6 scale with 1 being strongly disagree and 6 being strongly agree) and positively impacted their learning (4.52 ± 0.99 using the same scale). When used correctly, CPPRS can facilitate student learning in lectures.

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Amino acids and ammonium ions constitute the yeast assimilable nitrogen naturally present in apple juice, with free amino acids being the major constituent. Little information is available on the extent to which free amino acid composition in apple (Malus × domestica Borkh.) juice varies among juices used for fermentation. Twenty amino acids were quantified by UPLC‐PDA in juices from 13 apple cultivars grown in Virginia with potential use in cider making. The relative amino acid profile was significantly different among the apple juices evaluated. The total amino acid concentration ranged from 18 mg/L in Blacktwig juice to 57 mg/L in Enterprise juice. l‐Asparagine, l‐aspartic acid and l‐glutamine are the principal amino acids observed in most apple juices. Our results indicate that the relative concentration of amino acids in apples is different from that found in Vitis vinifera wine grapes, which are rich in l‐proline and l‐arginine. The impact of these differences on fermentation of apple juice by wine yeast strains warrants further research, as the amino acid composition of grape juice impacts wine quality both directly and indirectly via yeast metabolism. These results will inform future research on yeast metabolism and nitrogen management during cider fermentation. © 2018 The Authors Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling

Yeast assimilable nitrogen (YAN) concentration and composition impact hydrogen sulphide (H2S) production and fermentation kinetics during wine fermentation, but this phenomenon has not been extensively studied in cider fermentation. Our hypothesis was that H2S production during cider fermentation could be decreased through pre‐fermentation modification of concentrations of individual amino acids. Apple juice (53 mg L−1 YAN) was supplemented with asparagine, arginine, methionine or ammonium and fermented with EC1118 and UCD522 yeast strains. No difference in H2S production among fermentations was observed with addition of asparagine, arginine or ammonium. Methionine addition of 5 mg L−1 decreased H2S production by yeast strain EC1118 at 53 mg L−1 YAN. With 153 mg L−1 initial YAN, only methionine addition of 50 mg L−1 decreased H2S production, and no tested methionine rates decreased H2S production with 253 mg L−1 initial YAN. Supplementation to 153 mg L−1 YAN resulted in increased H2S production at all methionine concentrations tested. Sensory differences in aroma were detected in samples supplemented with ammonium and methionine, and these differences were correlated with observed differences in H2S production. Our results indicate that supplementing cider fermentations with methionine leads to lower H2S formation, especially in apple juice containing low YAN. © 2017 The Authors Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling