Changes in the electrical conductivity of foods during ohmic heating

Halden, K.; Alwis, A.A.P. de; Fryer, P.J.

doi:10.1111/j.1365-2621.1990.tb01055.x

Cited by 215 publications

(100 citation statements)

References 12 publications

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“…This approach was necessary in order to compute the electrical conductivity of soybean slurry. Electric conductivity depends on several factors like temperature, time, ionic constituents, material microstructure and field strength (Halden et al 1990). To evaluate the effect of time on electrical conductivity, experiments were planned to examine the time dependence of electrical conductivity.…”

Section: Methodsmentioning

confidence: 99%

Combined effect of ohmic heating and enzyme assisted aqueous extraction process on soy oil recovery

et al. 2012

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This research describes a new technological process for soybean oil extraction. The process deals with the combined effect of ohmic heating and enzyme assisted aqueous oil extraction process (EAEP) on enhancement of oil recovery from soybean seed. The experimental process consisted of following basic steps, namely, dehulling, wet grinding, enzymatic treatment, ohmic heating, aqueous extraction and centrifugation. The effect of ohmic heating parameters namely electric field strength (EFS), end point temperature (EPT) and holding time (HT) on aqueous oil extraction process were investigated. Three levels of electric field strength (i.e. OH600V, OH750V and OH900V), 3 levels of end point temperature (i.e. 70, 80 and 90°C) and 3 levels of holding time (i.e. 0, 5 and 10 min.) were taken as independent variables using full factorial design. Percentage oil recovery from soybean by EAEP alone and EAEP coupled with ohmic heating were 53.12 % and 56.86 % to 73 % respectively. The maximum oil recovery (73 %) was obtained when the sample was heated and maintained at 90°C using electric field strength of OH600V for a holding time of 10 min. The free fatty acid (FFA) of the extracted oil (i.e. in range of 0.97 to 1.29 %) was within the acceptable limit of 3 % (oleic acid) and 0.5-3 % prescribed respectively by PFA and BIS.

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Section: Methodsmentioning

confidence: 99%

Combined effect of ohmic heating and enzyme assisted aqueous extraction process on soy oil recovery

et al. 2012

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“…The EC increased with the process temperature from 20 to 80°C [33]. Ohmic heating rates are critically dependent on the EC of the foods [6].…”

Section: Introductionmentioning

confidence: 99%

Stabilization of Raw Rice Bran using Ohmic Heating

Dhingra

Chopra

2012

Agric Res

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Ohmic heating experiments for heating of raw rice bran were conducted using a Teflon cylindrical cell. Electrical conductivity (EC) values were evaluated for ohmic heating of rice bran at 20, 30, and 40 % moisture content (w.b.), by applying voltage gradients between 44 and 72 V/cm. The EC increased significantly with increase in temperature and moisture content but the variation in EC was not significant with the variation in voltage gradient. The linear temperature and moisture content-dependent EC relations were obtained. EC values for rice bran at 20 % moisture content were in the range 0.01-0.06 S/m within the entire temperature range of 25-100°C. Whereas, they were observed to be 0.04-0.14 and 0.08-0.23 S/m, respectively, for rice bran at 30 and 40 % m.c., w.b. An ohmic heating system having a capacity of 10 kg/batch was developed and evaluated for its performance. Ten kg rice bran was hydrated and heated by flow of electric current through it. The treated sample was observed to be stable even after 75 days of storage in comparison to raw rice bran sample. The % free fatty acid (FFA) in treated (ohmically heated) bran was observed to be 4.77 % after 75 days of storage whereas it was 41.84 % in case of raw bran. The FFA concentration of the ohmically heated samples increased very slowly in comparison to raw rice bran samples during 75 days of storage. The peroxide value and acid value of ohmically heated samples after 75 days of storage were 4.7 meq/kg and 9.34 %, respectively. Results showed that ohmic heating is an effective method for rice bran stabilization.

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“…La cantidad de calor generado esta´directamente relacionada con la corriente y el voltaje ele´ctrico aplicado (Sastry & Fa-Li, 1996), por lo que para poder usar el CO en el procesamiento de algu´n alimento debe considerarse: la cantidad de agua y iones, la forma y taman˜o de partı´cula, la viscosidad del alimento, entre otros (Camargo, Alves, Martins, & Vessoni, 2010). Existen un gran nu´mero de aplicaciones del CO en la industria de los alimentos, entre las cuales esta´n escaldado, pasterizacio´n, esterilizacio´n, descongelacio´n, evaporacio´n, deshidratacio´n, fermentacio´n y extraccio´n (Camargo et al, 2010;Halden, De Alwis, & Fryer, 1990;Simpson, Jime´nez, Carevic, & Grancelli, 2007;Wang & Sastry, 1993). En el an˜o 2003 habı´a 19 industrias que usaban CO para sus procesos, siendo Japo´n, Italia, Grecia, Gran Bretan˜a, EEUU y Me´xico paı´ses pioneros en el desarrollo de e´stas (Zell, Lyng, Cronin, & Morgan, 2009).…”

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