Department of Food Science and Technology, Oregon State University, Corvallis 97331.
Department of Food Science and Technology, Oregon State University, Corvallis 97331.
J Dairy Sci. 2019 Oct;102(10):8721-8733. doi: 10.3168/jds.2018-16236. Epub 2019 Aug 7.
Bloomy rind cheeses, including Brie, Camembert, and related varieties, are at high risk of contamination by environmental pathogens during manufacture and ripening. This risk is particularly high during ripening due to open-air exposure of the product. Currently, no kill step is applied after manufacture or post ripening to control food safety risks associated with Listeria monocytogenes contamination. Instead, cheesemakers must rely on sanitation and environmental monitoring to reduce this risk. High-pressure processing (HPP) is a nonthermal food-processing technology that can effectively reduce bacterial contaminants with minimal impact on the organoleptic properties of various foods. The objective of this study was to evaluate HPP as a potential intervention to maintain Camembert cheese quality and reduce risk associated with L. monocytogenes. Timing of HPP treatments (3, 11, and 45 d after manufacture) was based on the growth of L. monocytogenes during Camembert cheese ripening. High-pressure processing treatment of fully ripened cheeses (45 d) resulted in destruction of the surface mold, which caused browning and yellowing of the cheese rind. Applying HPP treatment earlier in the ripening process (11 d) resulted in a similar degradation of cheese appearance, which did not improve with continued ripening. Applying HPP treatment shortly after production (3 d; before the surface flora developed) delayed the development of the cheese rind and the textural ripening of the cheese. This early treatment time also resulted in free whey being expelled from the cheese, creating a firmer body. Applying HPP 11 d after manufacture resulted in >5 log reduction of L. monocytogenes at 450 and 550 MPa with holding times of 10 min. Although HPP was effective at reducing L. monocytogenes associated with bloomy rind cheeses, the quality deterioration would be unacceptable to consumers. Cheesemakers must continue to emphasize sanitation and environmental monitoring to reduce the risk of L. monocytogenes in bloomy rind cheeses.
花皮软质奶酪，包括布里干酪、卡门贝干酪和相关品种，在制造和成熟过程中极易受到环境病原体的污染。由于产品露天暴露，这种风险在成熟过程中尤其高。目前，在制造后或成熟后没有采用杀菌步骤来控制与单核细胞增生李斯特菌污染相关的食品安全风险。相反，奶酪制造商必须依靠卫生和环境监测来降低这种风险。超高压处理（HPP）是一种非热食品加工技术，可以在对各种食品的感官特性产生最小影响的情况下，有效减少细菌污染物。本研究的目的是评估 HPP 作为一种潜在的干预措施，以维持卡门贝干酪的质量并降低与单核细胞增生李斯特菌相关的风险。HPP 处理的时间（制造后 3、11 和 45 天）基于单核细胞增生李斯特菌在卡门贝干酪成熟过程中的生长情况。对完全成熟的奶酪（45 天）进行 HPP 处理会破坏表面霉菌，导致奶酪外皮变褐和变黄。在成熟过程中更早地进行 HPP 处理（11 天）会导致奶酪外观出现类似的降解，但随着成熟的继续，这种情况并没有改善。在生产后不久（3 天；在表面菌群发育之前）进行 HPP 处理会延迟奶酪外皮的发育和奶酪的质地成熟。这种早期处理时间还会导致奶酪中的乳清被挤出，使质地更坚硬。在制造后 11 天进行 HPP 处理，在 450 和 550 MPa 下，保持时间为 10 分钟，可使单核细胞增生李斯特菌减少 5 个对数级。尽管 HPP 可以有效地减少与花皮软质奶酪相关的单核细胞增生李斯特菌，但这种质量恶化对消费者来说是不可接受的。奶酪制造商必须继续强调卫生和环境监测，以降低花皮软质奶酪中单核细胞增生李斯特菌的风险。
