Moisture sorption isotherms of Nigerian millet at varying temperatures

Ajisegiri, Emmanuel S.A.; Sopade, P. A.

doi:10.1016/0260-8774(90)90003-q

Cited by 14 publications

(8 citation statements)

References 15 publications

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“…The procedure followed was the static gravimetric method (Spiess and Wolf 1983) as described in an earlier report (Ajisegiri and Sopade 1990). Samples for conditioning, and hence for EMC determinations, were obtained by a quartering technique from a 20-kg bag that was randomly chosen from a local warehouse.…”

Section: Determination Of Equilibrium Moisture Content (Emc)mentioning

confidence: 99%

“…The moisture adsorption and desorption behavior of foods is Journal of Food Process Engineering 17 (1994) (Labuza 1975;Chirife and Iglesias 1978;Boquet et al 1978) as important processing and storage parameter and it has been extensively studied (Iglesias and Chirife 1982;Demertzis et al 1989;Gevandan et al 1989;Diamante and Munro 1990;Tolaba and Suarez 1990). Nigeria as a case study of a developing country is endowed with a wide array of agricultural materials, some of which have been studied (Denloye and Ade-John 1985;Ajibola 1986a,b;Onayemi and Oluwamukomi 1987;Ajisegiri and Sopade 1990). Because of the size of the country and, consequently, the range of climatic regions, varietal differences occur from one part to the other.…”

Section: Introductionmentioning

confidence: 99%

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MOISTURE SORPTION STUDY ON NIGERIAN FOODS: MAIZE and SORGHUM

Sopade

Ajisegiri

1994

J Food Process Engineering

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Adsorption-desorption behavior of maize and sorghum between a, = 0.10 -0.98 at temperatures of 20, 25 and 40C was studied. The grains exhibited type I1 sorption isotherm. The sorption data were analyzed using six sorption models and the coeflcients of determination were between 0.6965-0.9994. The Caurie model gave the poorest fit and the Henderson model the best. Some models were better for adsorption than for desorption. The GAB and BET monolayer moisture contents were not significantly @ > 0.05) different. Monolayer values were temperature-dependent with activation energy from I . 36-10.08 MJ/moE and the maize monolayer values exhibited the highest sensitivity to temperature. Heat of sorption was obtained by applying Claussius-Clapeyron equation to the sorption isotherms at the three temperatures. The heat of sorption decreased with an increase in moisture content and an exponential equation was used to describe the relationship. The processing and storage consequences of this information were discussed.

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Section: Determination Of Equilibrium Moisture Content (Emc)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

MOISTURE SORPTION STUDY ON NIGERIAN FOODS: MAIZE and SORGHUM

Sopade

Ajisegiri

1994

J Food Process Engineering

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“…The harvested grains are dried to about 12% (d.b.) moisture content (Ajisegiri and Sopade 1990). The grain at around 12% moisture content are either dehulled or stored for dehulling application at later date.…”

Section: Introductionmentioning

confidence: 99%

Sorption Isotherms of Barnyard Millet Grain and Kernel

Singh

Mishra

Saha

2009

Food Bioprocess Technol

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The moisture sorption isotherms of grain and kernel of barnyard millet (Echinochloa frumentacea) were determined at 20, 30, 40, and 50°C. A gravimetric static method was used under 0.112-0.964 water activity (a w ) range for the determination of sorption isotherms. The models were compared using the coefficient of determination (r 2 ), reduced chi-square (χ 2 ) values, and on the basis of residual plots. In grain, modified Chung-Pfost (r 2 >0.99; χ 2 <0.7) and modified Oswin (r 2 >0.99; χ 2 <0.55) models were found suitable for predicting the M e -a w relationship for adsorption and desorption, respectively. Modified Henderson model was found to give the best fit (r 2 >0.99 and χ 2 <0.55) for describing the adsorption and desorption of the kernel. The isosteric heat, calculated using ClausiusClapeyron equation, was varied between 46.76 and 61.71 kJ g −1 mol −1 at moisture levels 7-21% (d.b.) for grain and 47.11-63.52 kJ g −1 mol −1 at moisture level between 4% and 20% (d.b.) for kernel. The monolayer moisture content values ranged from 4.3% to 6% d.b. in the case of adsorption of barnyard millet grain and 5.2-6.6% d. b. in the case of desorption at the temperature ranges of 50-20°C. The monolayer moisture values of barnyard millet kernel ranged from 4.4% to 6.67% d.b. in adsorption and 4.6% to 7.3% d.b. in desorption in the temperature ranges of 50-20°C. Keywords Sorption isotherm . Barnyard millet . Equilibrium moisture content . Water activity . Isosteric heat . Monolayer moisture Nomenclature A, B, C constants used in sorption models P, q, r constants used in monolayer moisture content models a w water activity, decimal ΔH latent heat of vaporization of pure water, kJ mol −1 (43.53 kJ mol −1 at 35°C) M moisture content, % (d.b.) M e equilibrium moisture content, % (d.b.) M ex experimental equilibrium moisture content, decimal M pr predicted equilibrium moisture content, decimal n number of constants N number of observation Q st isosteric heat sorption, kJ g −1 mol −1 q st net isosteric heat of sorption, kJ g −1 mol −1 R universal gas constant, kJ mol −1 K −1 (0.008314 kJ mol −1 K −1 ) r 2 coefficient of determination T temperature, K χ 2 reduced chi-square m o monolayer moisture content, % (d.b.) t temperature,°C

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“…This model describes well the behaviour of cereals and cereal starch (Ajisegiri, 1990;Boki & Ohno, 1991;Mok & Dick, 1991). 3.…”

Section: Mathematical Modelingmentioning

confidence: 96%