Department of Biology, University of Naples Federico II, Via Cinthia, 80126, Naples, Italy.
Department of Biology, University of Naples Federico II, Via Foria 223 - Orto Botanico, 80139, Naples, Italy.
BMC Microbiol. 2018 Jan 5;18(1):4. doi: 10.1186/s12866-017-1142-z.
Drinking tea constitutes a tradition which is deeply rooted in the culture of several countries. Moreover, in recent years, tea consumption is growing all over the world. Improper herbal tea storage (long periods, humid environments) represents a relevant health hazard for consumers because of the growth of bacteria and molds.
This study analyzed 32 samples of commercially available black and green teas - purchased from southern Italy markets and online-shops - and the monitoring of microbiological quality of the tea bag content was performed. Evaluations were conducted with the aim of characterizing pathogens indicated by the European and American guidelines (total bacterial count, fungi and Escherichia coli) and on the research of Pseudomonas spp. and Clostridium perfringens. The presence of ochratoxin A in tea matrix-leaves and infusions was further assessed, using a validated and accredited HPLC-FLD method. Microbial loads, for over 80% samples, ranged from 1.0 × 10 to 2.8 × 10 CFU/g tea: most of identified microorganisms were classified as Bacillaceae. The utilization of rapid detection and identification methods (PCR and sequencing), allowed the characterization of strains of Pseudomonas psychrotolerans, Staphylococcus warneri, Pantoea gaviniae and the isolation of one strain of Clostridium perfringens, whose ability to produce toxins can result in harmful outcomes for consumers. Fungi were isolated from 70% samples: the most prevalent molds were Aspergillus niger strains, followed by Aspergillus tubingensis. Ochratoxin A was detected in 22 of 32 tea solid samples investigated: concentrations resulted over the indicated limits for food products for 50% samples.
Results obtained demonstrated the need to develop targeted regulations for the safety of herbal teas.
饮茶是一些国家文化中根深蒂固的传统。此外，近年来，全球茶叶消费不断增长。由于细菌和霉菌的生长，草药茶储存不当（长时间、潮湿的环境）对消费者的健康构成了重大威胁。
本研究分析了从意大利南部市场和网店购买的 32 份市售黑茶和绿茶样本，并对茶包内容物的微生物质量进行了监测。评估的目的是对欧洲和美国指南（总细菌计数、真菌和大肠杆菌）所指示的病原体进行特征描述，并对假单胞菌和产气荚膜梭菌进行研究。采用经验证和认可的 HPLC-FLD 方法，进一步评估了茶叶基质叶片和浸出液中赭曲霉毒素 A 的存在。超过 80%样本的微生物负荷范围为 1.0×10 至 2.8×10 CFU/g 茶叶：大多数鉴定出的微生物被归类为芽孢杆菌科。快速检测和鉴定方法（PCR 和测序）的应用，使鉴定出的假单胞菌耐寒型、沃氏葡萄球菌、泛菌属和一株产气荚膜梭菌的菌株特征化成为可能，这些菌株产生毒素的能力可能对消费者造成有害后果。70%的样本中分离出真菌：最常见的霉菌是黑曲霉株，其次是突脐拟青霉。在所研究的 32 个茶固体样本中，有 22 个检测到赭曲霉毒素 A：50%的样本浓度超过了食品产品的指示限值。
研究结果表明，有必要针对草药茶的安全性制定有针对性的法规。
