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Research Project: Improved Processes for the Preservation and Utilization of Vegetables, Including Cucumber, Sweetpotato, Cabbage, and Peppers to Produce Safe, High Quality Products with Reduced Energy Use and Waste

Location: Food Science Research

Title: Fermentation cover brine reformulation for cucumber processing with low salt to reduce bloater defect

item ZHAI, YAWEN - North Carolina State University
item Perez Diaz, Ilenys

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2017
Publication Date: 12/1/2017
Citation: Zhai, Y., Perez Diaz, I.M. 2017. Fermentation cover brine reformulation for cucumber processing with low salt to reduce bloater defect. Journal of Food Science. 82(12):2987-2996.

Interpretive Summary: Efforts to improve/optimize low salt cucumber fermentations to reduce formation of hollow cavities in the finished preserve are underway. The impact of brine reformulation using ingredients typically used in the pickling industry in the USA was studied. This publication discusses the results of such efforts and the optimization strategies currently under consideration. Essentially it was learned that supplementation of brines with calcium hydroxide, 2% sodium chloride and vinegar aids in the reduction of the hollow cavity formation defect. A combination of high levels of a dominant starter culture with the newly proposed brine composition was found to aid in significantly reducing the defect.

Technical Abstract: Reformulation of calcium chloride cover brine for cucumber fermentation was explored as a mean to minimize the incidence of bloater defect. This study particularly focused on cover brine supplementation with calcium hydroxide, sodium chloride (NaCl), and acids to enhance buffer capacity, inhibit the indigenous carbon dioxide- producing microbiota, and decrease the solubility of the gas. The influence of the cover brine formulations tested, on the cucumber fermentation microbiota, biochemistry, carbon dioxide production, and bloating defect was studied using metagenetics, HPLC analysis, a portable gas analyzer and bloater index, respectively. Cover brine supplementation with calcium hydroxide and acetic acid resulted in complete fermentations with final pH values 0.5 units higher than the un-supplemented control. Lactic acid production increased by approximately 22%, possibly inducing the observed reduction in the relative abundance of Enterobacteriaceae by 92%. Calcium hydroxide supplementation also resulted in an increased relative abundance of Leuconostocaceae by 7%, which likely contributed to the observed increment in carbon dioxide levels by 25%. A 50% reduction on acetic acid formation was detected when cover brines were supplemented with calcium hydroxide and 690 mM (4%) NaCl. No significant difference was observed in bloater index as the result of calcium hydroxide or NaCl supplementation in cover brines, given that the carbon dioxide levels remained at above the 20 mg/100 mL needed to induce the defect. It is concluded that the modified cover brine formulation containing calcium hydroxide and NaCl enables the complete conversion of sugars, decreases production of carbon dioxide and levels of Enterobacteriaceae, but insignificantly reduces bloater index.