H&TRC- Health & Technology Research Center, ESTeSL- Escola Superior de Tecnologia da Saúde, Instituto Politécnico de Lisboa, Portugal; NOVA National School of Public Health, Public Health Research Centre, Universidade NOVA de Lisboa, Portugal; Comprehensive Health Research Center (CHRC), Portugal.
H&TRC- Health & Technology Research Center, ESTeSL- Escola Superior de Tecnologia da Saúde, Instituto Politécnico de Lisboa, Portugal.
Int J Food Microbiol. 2020 Nov 16;333:108795. doi: 10.1016/j.ijfoodmicro.2020.108795. Epub 2020 Jul 22.
In recent times green tea (GT) consumption has increased, due to the numerous studies that indicate a wide variety of health benefits following its regular consumption. The aim of this study was to assess the bioburden (bacteria and fungi) of bulk and bags of GT marketed in Lisbon and to obtain a more refined fungal burden characterization, including azole resistance profile. The bacteriota in tea bags before boiling ranged from lower than the detection limit to 1770 CFU.g, whereas in brew samples ranged from lower than the detection limit to 54.55 CFU.mL. In bulk samples before boiling ranged from lower than the detection limit to 2636 CFU.g, while after boiling ranged from lower than the detection limit to 72.73 CFU.mL. Fungal contamination on tea bags before boiling ranged from lower than the detection limit to 66.67 CFU.g and after boiling, all samples presented results lower than the detection limit. Concerning bulk samples before boiling ranged from lower than the detection limit to 96.97 CFU.g, whereas after boiling ranged from lower the detection limit to 30.3 CFU.mL. Before boiling, the most common fungal species in the bagged tea (90.91 CFU.g; 45.45%) and bulk samples (66.67 CFU.g; 91.67%) was Aspergillus section Nigri. Fungal diversity was higher on bulk samples than in tea bags. Aspergillus section Nigri and Rhizopus sp. growth was observed mostly on itraconazole-supplemented Sabouraud dextrose agar media, which require further investigation. Aspergillus sections Fumigati and Nidulantes were detected by using real time PCR, but not in the GT samples in which they were identified through culture-based methods. A significantly reduction of bacterial contamination after boiling was observed, however fungal contamination with toxigenic potential was observed before and after boiling. Future research work needs to characterize in detail the mycotoxins contamination to allow a risk-benefit assessment to estimate the human health benefits and risks following tea consumption and to support policy-actions, if and when needed. The results also suggest that the conditions how tea is packed can influence the fungal diversity and this variable should be further investigated.
近年来，由于大量研究表明经常饮用绿茶（GT）可带来多种健康益处，因此绿茶的消费有所增加。本研究的目的是评估在里斯本销售的散装和袋装 GT 的生物负荷（细菌和真菌），并更精细地描述真菌负荷特征，包括唑类耐药谱。煮沸前茶包中的细菌数量从检测限以下到 1770 CFU.g，而冲泡样品中的数量从检测限以下到 54.55 CFU.mL。在煮沸前的散装样品中，从检测限以下到 2636 CFU.g，而煮沸后从检测限以下到 72.73 CFU.mL。煮沸前茶包中的真菌污染从检测限以下到 66.67 CFU.g，煮沸后，所有样品的结果均低于检测限。关于散装样品，煮沸前从检测限以下到 96.97 CFU.g，煮沸后从检测限以下到 30.3 CFU.mL。煮沸前，袋装茶（90.91 CFU.g；45.45%）和散装样品（66.67 CFU.g；91.67%）中最常见的真菌种类是黑曲霉。散装样品中的真菌多样性高于茶包。黑曲霉和根霉在伊曲康唑补充的萨布罗琼脂培养基上的生长最为明显，这需要进一步研究。通过实时 PCR 检测到了青霉属和拟青霉属，但在未通过基于培养的方法鉴定的 GT 样品中未检测到。在煮沸后观察到细菌污染显著减少，但在煮沸前后均观察到具有潜在毒性的真菌污染。需要开展进一步的研究工作，以详细描述真菌毒素污染情况，从而能够对饮茶带来的健康效益和风险进行风险效益评估，并在需要时支持相关政策行动。研究结果还表明，茶叶包装方式可能会影响真菌多样性，这一变量需要进一步研究。
