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The effect of blanching by ohmic heating (OH) on the kinetics of osmotic dehydration of strawberries was studied. Ohmic heating parameters obtained at two temperatures (65 and 85°C). The osmotic dehydration (OD) parameters are the temperature (26 and 37°C) and the sucrose in osmotic solution (30-70°B). An approximate solution of Fick's law for unsteady state mass transfer in spherical configuration has been used to calculate the effective diffusion coefficients of water and sucrose. Results show that ohmic heating increases drastically the mass transfer and the effective diffusion rates. After 4 h of OD (without OH) in a sucrose solution (at 37°C and 70°B), the dry matter of the untreated strawberry halves was 20.3%; while it reached 68% when OD was combined with blanching by OH at 85°C for 3-min. Ohmic blanching permits the effective damage of cells by combination of electrical and thermal effects. That result has an important enhancement of water and sugar transfers during osmotic dehydration of strawberries.Nomenclature OD osmotic dehydration. OH ohmic heating.°B Brix C e concentration at equilibrium, g/g. C sugar concentration in the fruit, g/g. C 0 initial sugar concentration, g/g. D eq equivalent diffusion coefficient for the spherical fruit, m 2 /s. D 1/2 effective diffusion coefficient for the semispherical fruit, m 2 /s. D w effective diffusion coefficient of water for the spherical fruit, m 2 /s. D s effective diffusion coefficient of sugar for the spherical fruit, m 2 /s. D w1/2 effective diffusion coefficient of water for the semi-spherical fruit, m 2 /s. D s1/2 effective diffusion coefficient of sugar for the semi-spherical fruit, m 2 /s. R 1/2 radius of semi-sphere, m. R eq radius of sphere, m. S eq surface of spherical fruit, m 2 . S 1/2 surface of semi-spherical fruit, m 2 . SG sugar gain, g/g. SG t sugar gain at time t, g/g. SG 0 sugar gain at time 0, g/g. SG ∞ sugar gain at equilibrium, g/g. t immersion time, s. W t fruit weight at the end of treatment, g. WL water loss, g/g. WL t water loss at time t, g/g. WL 0 water loss at time 0, g/g. WL ∞ water loss at equilibrium, g/g. WL/SG selectivity.

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The aim of this work was to study the efficiency of inactivation of Escherichia coli cells in aqueous suspensions using combined moderate pulsed electric field (PEF) and thermal treatments. The inactivation kinetics of E. coli cells in aqueous suspensions (1 wt%) was monitored using conductometric technique. The electric field strength E was within 5-7.5 kV/cm, the effective PEF treatment time was within 0-0.75 s, the pulse duration ti was within 0.3-1 ms, the medium temperature was 30-50°C, and the time of thermal treatment tT was within 0-7000 s. The organic acid concentration was within 0-0.5 g/L.The damage of E. coli was accompanied by release of intracellular components. The synergy between the PEF and thermal treatments in E. coli inactivation was clearly demonstrated. The damage efficiency was noticeably improved by addition of organic acids, especially lactic acid.