Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC 27698-7624, USA.
J Food Sci. 2012 Oct;77(10):M586-92. doi: 10.1111/j.1750-3841.2012.02845.x. Epub 2012 Aug 27.
Calcium chloride fermentations represent an alternative to reduce chloride concentrations in the wastewaters generated from commercial cucumber fermentations, currently performed in cover brine solutions containing 6% to 12% sodium chloride. However, preliminary attempts to commercially ferment the cucumbers in the presence of oxygen led to the development of a secondary cucumber fermentation or spoilage. The development of cucumber secondary fermentation has also been occasionally reported by processors using cover brine solutions containing sodium chloride. This study focused on the development of a model system to characterize CaCl(2) and NaCl secondary cucumber fermentations under conditions similar to those present on the commercial scale. Cucumber fruits mixed with cover brine solutions, containing 100 mM CaCl(2) or 1.03 M NaCl, and 25 mM acetic acid, were fermented in 2 L fermentation vessels subjected to air-purging at a rate of 5 mL/min. Microorganisms and selected biochemical changes detected in the experimental cucumber fermentations had been previously observed in commercial spoilage samples, suggesting the successful reproduction of the secondary fermentation in the laboratory. Experimental secondary fermentations were characterized by the rapid oxidation of the lactic acid produced during the primary fermentation, which, in turn, increased pH. Lactic acid disappearance seemed to be the result of yeast metabolism that also led to the chemical reduction of the environment to levels at which other bacteria could become established and produce butyric, propionic, and acetic acids. This model system will be applied for the identification of strategies to prevent the initiation of the cucumber secondary fermentation and reduce economic losses in the pickling industry.
The study of secondary cucumber fermentation has represented a challenge for many years. The successful development of a model system for the study of this phenomenon in the laboratory is instrumental in furthering the study of the event and in optimizing the sodium-chloride-free fermentation at the commercial scale.
氯化钙发酵是减少商业黄瓜发酵废水中氯化物浓度的一种替代方法，目前在含有 6%至 12%氯化钠的覆盖盐水中进行。然而，初步尝试在有氧条件下商业发酵黄瓜会导致二次黄瓜发酵或变质。使用含有氯化钠的覆盖盐溶液的加工商偶尔也会报告黄瓜二次发酵的发展。本研究专注于开发一种模型系统，以在类似于商业规模的条件下对氯化钙和氯化钠二次黄瓜发酵进行特征描述。将与覆盖盐溶液（含 100mM CaCl2 或 1.03M NaCl 和 25mM 乙酸）混合的黄瓜果实装入 2L 发酵罐中，在 5mL/min 的空气吹扫速率下进行发酵。在实验黄瓜发酵中检测到的微生物和选定的生化变化先前在商业变质样品中观察到，这表明在实验室中成功再现了二次发酵。实验性二次发酵的特征是初级发酵过程中产生的乳酸迅速氧化，这反过来又增加了 pH 值。乳酸的消失似乎是酵母代谢的结果，这也导致环境的化学还原到其他细菌可以建立并产生丁酸、丙酸和乙酸的水平。该模型系统将用于确定防止黄瓜二次发酵开始和减少腌制工业经济损失的策略。
多年来，二次黄瓜发酵的研究一直是一个挑战。成功开发出用于在实验室中研究该现象的模型系统，有助于进一步研究该现象，并在商业规模上优化无氯化钠发酵。
