Food Chemistry and Bioactivity Laboratory & Coffee Research Core (NUPECAFÉ), Nutrition Institute, Federal University of Rio de Janeiro (UFRJ), Brazil; Food Microbiology Laboratory, Institute of Microbiology, UFRJ, Brazil.
Food Chemistry and Bioactivity Laboratory & Coffee Research Core (NUPECAFÉ), Nutrition Institute, Federal University of Rio de Janeiro (UFRJ), Brazil.
Food Res Int. 2023 Dec;174(Pt 2):113667. doi: 10.1016/j.foodres.2023.113667. Epub 2023 Nov 4.
Coffee cold brews have been gaining prominence and popularity among consumers worldwide. However, only a few studies have systematically analyzed their chemical composition or evaluated microbiological safety aspects. This study aimed to evaluate the survival of Bacillus cereus and Escherichia coli in cold brews prepared from roasted and ground Coffea arabica and C. canephora seeds using the following preparation methods: immersion without filter (INF), immersion in a cotton filter bag (ICF), vacuum (Vac.) and cold dripping (Drip.). Traditional hot dripping methods using filter paper (HDFP) and cotton filter (HDCF) were also tested for comparison. Water at 4 °C or 25 °C was intentionally contaminated (10 CFU/mL) with cells of Escherichia coli ATCC 25922 (EC) and Bacillus cereus F4433 (BC) before coffee extraction and refrigeration at 4 °C. Coffee concentrations of 5, 10, and 15% were tested. Analyses of pH, soluble solids, nine chlorogenic acids and two lactones (CGA), caffeine, trigonelline, and melanoidins were performed. Results were compared by ANOVA, followed by the Fisher's test, Pearson correlation, Variable Importance in Projection (VIP), and Cluster analyses, with a significance level of 5%. EC and BC were not detected (<10 CFU/mL and < 1 CFU/mL, respectively) after preparing C. arabica and C. canephora hot brews. In cold brews, the higher the extraction of soluble solids and bioactive compounds (with the highest occurring at 25 °C), the lower the counts of inoculated microorganisms during 24 h of storage. BC was not detected after 24 h of extraction and/or storage in the drinks obtained by ICF and Drip. at 5%, 10%, and 15% and INF and Vac. at 15%. EC was not detected in ICF and Drip. at 10 and 15%, and in INF at 15%. C. canephora brews exhibited higher levels of soluble solids, CGA, caffeine, and melanoidins than C. arabica brews. Based on these results, it can be concluded that in the absence of thermal processing as in hot brews, more concentrated cold brews, such as 15%, produced at 25 °C by dripping and immersion methods, are preferable for later dilution due to the higher content of soluble solids and bioactive compounds that contribute reducing the number of microorganisms in the beverage.
冷萃咖啡在全球消费者中越来越受欢迎。然而，只有少数研究系统地分析了其化学组成或评估了微生物安全方面。本研究旨在评估使用以下制备方法从烘焙和研磨的阿拉比卡咖啡（Coffea arabica）和罗布斯塔咖啡（C. canephora）种子中制备的冷萃咖啡中蜡样芽孢杆菌（Bacillus cereus）和大肠杆菌（Escherichia coli）的存活情况：无滤器浸泡（INF）、棉滤器浸泡（ICF）、真空（Vac.）和冷滴滤（Drip.）。还测试了传统的使用滤纸（HDFP）和棉滤器（HDCF）的热滴滤方法进行比较。在咖啡提取和 4°C 冷藏之前，将水（4°C 或 25°C）故意用大肠杆菌 ATCC 25922（EC）和蜡样芽孢杆菌 F4433（BC）细胞污染（10 CFU/mL）。测试了 5%、10%和 15%的咖啡浓度。进行了 pH 值、可溶性固体、九种绿原酸和两种内酯（CGA）、咖啡因、葫芦巴碱和类黑素的分析。通过方差分析、Fisher 检验、Pearson 相关性、变量重要性投影（VIP）和聚类分析进行比较，显著性水平为 5%。在制备阿拉比卡咖啡和罗布斯塔咖啡热咖啡后，未检测到 EC 和 BC（<10 CFU/mL 和 <1 CFU/mL，分别）。在冷萃咖啡中，提取的可溶性固体和生物活性化合物越多（在 25°C 时最高），在 24 小时储存期间接种微生物的数量就越低。在 INF 和 Vac.中，在 5%、10%和 15%以及在 ICF 和 Drip.中在 15%下提取和/或储存 24 小时后未检测到 BC。在 10%和 15%的 ICF 和 Drip.以及 15%的 INF 中未检测到 EC。罗布斯塔咖啡酿造物的可溶性固体、CGA、咖啡因和类黑素含量高于阿拉比卡咖啡酿造物。基于这些结果，可以得出结论，在不存在热加工（如热酿造物）的情况下，更浓缩的冷酿造物（例如通过滴滤和浸泡方法在 25°C 下生产的 15%）更适合后续稀释，因为可溶性固体和生物活性化合物的含量更高，这有助于减少饮料中的微生物数量。
