Dept. Food, Bioprocessing and Nutrition Sciences, 400 Dan Allen Drive, North Carolina State Univ., Raleigh, NC 27698-7624, USA.
J Food Sci. 2013 Feb;78(2):M264-9. doi: 10.1111/j.1750-3841.2012.02968.x. Epub 2013 Jan 18.
Refrigerated cucumber pickle products cannot be heat processed due to the loss of characteristic sensory attributes. Typically brined refrigerated pickles contain less than 100 mM acetic acid with pH values of 3.7 to 4.0. Refrigeration (4 to 10 °C) helps to inhibit the growth of spoilage bacteria and maintain flavor, texture, and appearance of the pickles. Previous research has shown that pathogenic Escherichia coli strains are unusually acid resistant and survive better in refrigerated acid solutions than at higher temperatures. We found that E. coli O157:H7 can survive for 1 mo or longer at 4 °C in brines typical of commercial refrigerated pickles. Our objective was to develop methods to assure a 5-log reduction of pathogenic E. coli in these types of products, while maintaining the sensory characteristics. A novel brine formulation was developed, based on current commercial refrigerated pickle brines, which contained 25 mM fumaric acid, 5 mM benzoic acid, 70 mM acetic acid, and 342 mM (2%) sodium chloride, with a pH of 3.8. Sensory data indicate that this formulation did not affect flavor or other sensory attributes of the product, compared to traditional formulations. We achieved a 5-log reduction of E. coli O157:H7 at 30 °C for 1.52 ± 0.15 d, at 20 °C for 3.12 ± 0.34 d, or at 10 °C for 8.83 ± 0.56 d. Growth of lactic acid bacteria was also inhibited. These results can be used by manufacturers to assure a 5-log reduction in cell numbers of E. coli O157:H7 and Salmonella without a heat process during the manufacture of refrigerated pickle products.
While refrigerated acidified vegetable products are exempt from the acidified foods regulations, we have shown that the vegetative microbial pathogens E. coli O157:H7 can survive for up to 1 mo in these products, given current commercial production practices. To improve the safety of refrigerated pickle products, a brine formulation with reduced acetic acid, but containing fumaric acid, was developed to assure a 5-log reduction in cell numbers of E. coli O157:H7 without a heat process. The formulation can be used to assure the safety of refrigerated pickled vegetables without altering sensory characteristics.
由于冷藏腌黄瓜制品会失去其特有的感官属性，因此不能进行热处理。通常，腌制的冷藏泡菜中的醋酸含量低于 100mM，pH 值为 3.7 至 4.0。冷藏（4 至 10°C）有助于抑制腐败细菌的生长，保持泡菜的风味、质地和外观。先前的研究表明，致病性大肠杆菌菌株对酸具有异常的抵抗力，在冷藏的酸性溶液中比在较高温度下更能存活。我们发现，大肠杆菌 O157:H7 在商业冷藏泡菜中典型的盐水中可在 4°C 下存活 1 个月或更长时间。我们的目标是开发一种方法，以确保在保持感官特性的同时，使这类产品中的致病性大肠杆菌减少 5 个对数级。为此，我们开发了一种基于当前商业冷藏泡菜盐水的新型盐水配方，其中含有 25mM 富马酸、5mM 苯甲酸、70mM 乙酸和 342mM（2%）氯化钠，pH 值为 3.8。感官数据表明，与传统配方相比，该配方不会影响产品的风味或其他感官属性。我们在 30°C 下实现了大肠杆菌 O157:H7 的 5 个对数级减少，用时 1.52 ± 0.15d；在 20°C 下实现了 3.12 ± 0.34d；在 10°C 下实现了 8.83 ± 0.56d。同时也抑制了乳酸菌的生长。制造商可以利用这些结果，在不进行热处理的情况下，确保在冷藏泡菜产品的生产过程中，大肠杆菌 O157:H7 和沙门氏菌的数量减少 5 个对数级。
虽然冷藏酸化蔬菜产品不受酸化食品法规的限制，但我们已经表明，在当前的商业生产实践中，营养型微生物病原体大肠杆菌 O157:H7 可以在这些产品中存活长达 1 个月。为了提高冷藏泡菜产品的安全性，我们开发了一种含有较低乙酸但含有富马酸的盐水配方，在不进行热处理的情况下，可确保大肠杆菌 O157:H7 的数量减少 5 个对数级。该配方可用于确保冷藏腌制蔬菜的安全性，而不会改变感官特性。
