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ARS Home » Southeast Area » Raleigh, North Carolina » Food Science Research » Research » Publications at this Location » Publication #114207


item Fasina, Oladiran
item Fleming, Henry
item McFeeters, Roger

Submitted to: Journal of Food Process Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2002
Publication Date: 5/1/2002
Citation: Fasina, O.O., Fleming, H.P., McFeeters, R.F. 2002. Thermal and rheological properties of brine from fermented and sulfite-preserved cucumbers. Journal of Food Process Engineering 25:307-322.

Interpretive Summary: Traditionally, brined cucumbers contain such high concentrations of salt that some of it must be leached out before making them into finished pickle products. However, many pickle companies cannot meet the current EPA guideline of 230 ppm of chloride limit in their wastewater discharge, creating a waste disposal problem. Recently, our laboratory has focused on two ways to reduce/eliminate the amount of salt used in vegetable preservation, including: (1) brining cucumbers at lower salt content by use of controlled fermentation methods, and (2) storage of pickling cucumbers in the absence of salt by use of chemical preservatives to prevent growth of spoilage microorganisms. Brines generated by these methods must be pumped to and from storage tanks. In this study, thermal and rheological properties important to the optimal design of suitable systems for the storage and pumping of brine were determined. Results indicate that temperature and salt content significantly affected these properties. The values of these properties were also higher than that of water. Thermal and rheological properties of brine obtained from this study will form part of the overall objective of developing an environmentally friendly and microbially safe process for the preservation of vegetables. The results from this study will be used by engineers and technical personnel involved in the handling and storage of brine obtained from preservation of cucumbers and other vegetables.

Technical Abstract: Pickling cucumbers may be temporarily preserved by fermentation in brine (6-8% NaCl) or without fermentation in salt-free, sulfite solution (300 ppm sulfite, pH 3.5). Brines obtained from preservation processes are often discarded. Due to environmental concerns, there is increasing consideration for further use of the brine solutions by recycling for use in bulk storage or filtration and incorporation into finished products. Thermal and rheological properties are fundamental to the reuse of the brine. The effect of temperature was determined on the rheological (5-45C) and thermal properties (5-75C) of brine. The properties of the brine samples were found to be significantly different (P less than 0.05) from each other and from water. Salt content was the most important factor affecting the thermal and rheological properties of brine. At the same conditions, the values of the properties (thermal conductivity, specific heat, and thermal diffusivity, viscosity) were about 5 to 23% less than the corresponding values for water.