Institute for Food Quality and Food Safety, University of Veterinary Medicine Hannover, Hanover, Germany.
J Food Sci. 2024 Sep;89(9):5799-5811. doi: 10.1111/1750-3841.17309. Epub 2024 Aug 21.
The present study investigated the microbiological safety of the increasingly popular plant-based milk alternatives. No (10/27) or only very low microbial counts (17/27) were detected in the tested products. These were mainly identified as spore formers via MALDI-ToF-MS. Three products contained Bacillus cereus group isolates, which were able to form considerable amounts of enterotoxins and exhibited cytotoxicity towards CaCo-2 cells. Preliminary tests showed good growth of B. cereus, Listeria monocytogenes, and Salmonella enterica in all tested products (maximum bacterial counts: 5 × 10 cfu/mL). These experiments also revealed strain-, time-, and temperature-, but especially product-specific enterotoxin production of B. cereus. In propagation and persistence tests according to DIN EN ISO 20976-1:2019-09, rapid bacterial proliferation was also detected in all products. B. cereus generally showed lower bacterial counts (10-10 cfu/mL) compared to L. monocytogenes and S. enterica (10-10 cfu/mL), but was detectable in a larger number of products over the test period of 6 weeks. pH values decreased (20/27) over time and visual and/or olfactory alterations (24/27) were observed. The present study provides information on the occurrence, growth and persistence of pathogenic bacteria in plant-based drinking milk alternatives. It also points out that the accompanying changes in pH, odor, and appearance are not necessarily recognizable to the consumer. PRACTICAL APPLICATION: The present study contributes to the understanding of the microbial risk related to plant-based drinking milk alternatives. It is crucial that the manufacturer ensures that particularly spore formers have been effectively eliminated from the products. Among them, especially toxin-producing bacteria can pose a risk to the consumer, as these products promote proliferation and persistence of the bacteria.
本研究调查了日益流行的植物性奶替代品的微生物安全性。在所测试的产品中，（10/27）或仅检测到非常低的微生物计数（17/27）。这些主要通过 MALDI-ToF-MS 鉴定为孢子形成菌。三种产品含有蜡样芽胞杆菌组分离株，这些分离株能够形成相当数量的肠毒素，并对 CaCo-2 细胞表现出细胞毒性。初步测试表明，在所有测试产品中，蜡样芽胞杆菌、单核细胞增生李斯特菌和肠炎沙门氏菌均具有良好的生长能力（最大细菌计数：5×10 cfu/mL）。这些实验还揭示了蜡样芽胞杆菌的菌株、时间、温度和产品特异性肠毒素产生。在根据 DIN EN ISO 20976-1:2019-09 进行的繁殖和持久性测试中，也在所有产品中检测到快速的细菌增殖。与单核细胞增生李斯特菌和肠炎沙门氏菌相比，蜡样芽胞杆菌的细菌计数一般较低（10-10 cfu/mL），但在 6 周的测试期内，可在更多产品中检测到。随着时间的推移，pH 值降低（20/27），并观察到视觉和/或嗅觉变化（24/27）。本研究提供了有关植物性饮用奶替代品中致病菌的发生、生长和持久性的信息。它还指出，pH 值、气味和外观的伴随变化不一定被消费者识别。实际应用：本研究有助于理解与植物性饮用奶替代品相关的微生物风险。制造商必须确保产品中已有效消除特别是孢子形成菌。其中，产毒细菌尤其会对消费者构成风险，因为这些产品会促进细菌的增殖和持久性。
