Khảo sát mức độ nhiễm Listeria monocytogenes trên rau má và đồ uống nước rau má tươi tại khu vực Nha Trang, tỉnh Khánh Hòa

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Ngôn ngữ: vie

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Thông tin xuất bản: Tạp chí Kiểm nghiệm và An toàn thực phẩm, 2022

Mô tả vật lý: tr.525-532

Bộ sưu tập: Báo, Tạp chí

ID: 335623

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Gotu kola is often used to make fresh juice without heating. In Nha Trang, gotu kola drinks are usually prepared and refrigerated while being traded. Listeria monocytogenes is a bacterium capable of growing at cold temperatures
whereas the pathogenicity is low, mortality rate can be up to 25 - 30%. Therefore, the assessment of the level of L. monocytogenes contamination on raw gotu kola and in gotu kola juice during cold storage is crucial to ensure food safety and hygiene. This study has shown that the prevalence of L. monocytogenes infection on raw gotu kola cultivated in Nha Trang accounted for 15% of the samples with an average infection density of 24.2 MPN/g, in which gotu kola grown in wastewater field had the highest density of bacteria. Soaking raw vegetables in a solution of potassium permanganate 10 ppm/10 minutes has appeared to reduce the amount of L. monocytogenes by 56%. During the first 6 hours of storage, the amount of L. monocytogenes in gotu kola juice was stable at low level. After 24 hours of storage, the number of bacteria increased tenfold (on gotu kola juice without sugar) and twentyfold (on gotu kola juice with sugar) depending on storage temperature. Noticeably, the addition of sugar in gotu kola juice may have increased the growth of bacteria. Test results of forty-five samples of gotu kola juice sold on the streets of Nha Trang have revealed that the infection rate of L. monocytogenes was 6.67% and the average bacterial density was 5.43 MPN/mL. Thus, consumers need to pay attention to the origin and the manufacturing process of crude materials and should not use this herbal beverage from 6 hours after storage to reduce the possibility of disease caused by L. monocytogenes.Rau má là loại rau thường được sử dụng làm đồ uống nước ép tươi không qua gia nhiệt. Tại Nha Trang, đồ uống nước ép rau má thường được chế biến sẵn, bảo quản lạnh trong suốt quá trình bày bán rộng rãi trên đường phố. Trong đó, Listeria monocytogenes là loại vi khuẩn có khả năng phát triển ở nhiệt độ lạnh, tuy mức độ gây bệnh thấp nhưng tỷ lệ tử vong lên tới 25 - 30%. Do đó, việc đánh giá mức độ nhiễm L. monocytogenes trên rau má nguyên liệu và trong đồ uống nước ép rau má trong quá trình bảo quản lạnh là cần thiết nhằm đảm bảo an toàn vệ sinh thực phẩm. Kết quả nghiên cứu cho thấy tỷ lệ nhiễm L. monocytogenes trên rau má nguyên liệu chiếm 15% các mẫu lấy tại vùng trồng ở Nha Trang với mật độ nhiễm trung bình là 24,2 MPN/g, trong đó mẫu rau má ruộng nước thải có mật độ vi khuẩn cao nhất. Kết quả ngâm rau nguyên liệu trong dung dịch KMnO4 10 ppm/10 phút làm giảm 56% tỷ lệ nhiễm L. monocytogenes. Trong 6 giờ bảo quản đầu, số lượng L. monocytogenes trong nước ép rau má ổn định ở mức độ thấp. Sau 24 giờ bảo quản, số lượng vi khuẩn tăng gấp gần 10 lần (trên nước ép rau má không đường) và gần 20 lần (trên nước ép rau má có đường) tùy theo nhiệt độ bảo quản. Việc bổ sung đường trong nước rau má đã làm tăng phát triển của vi khuẩn. Kết quả kiểm tra 45 mẫu nước ép rau má bày bán trên đường phố Nha Trang cho thấy tỷ lệ nhiễm L. monocytogenes là 6,67% và mật độ vi khuẩn trung bình là 5,43 MPN/mL. Như vậy, người tiêu dùng cần chú ý nguồn gốc, cách xử lý nguyên liệu và không nên sử dụng loại đồ uống này quá 6 giờ sau khi bảo quản để giảm khả năng mắc bệnh do tác nhân L. monocytogenes gây ra.

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