Water desorption isotherms of fermented cocoa beans from Ivory Coast were determined using the gravimetric static method of saturated salts solutions at 30 °C, 40 °C and 60 °C, and isosteric heats of desorption were calculated from Clausius-Clapeyron equation. The experimental data were fitted to several isotherm equations. The best fittings were obtained for the BET equation for aw<0.50 (with an average mean relative deviation (MRD) value of 1.56%) and for the Harkins-Jura equation for aw≥0.50 (with an average value MRD equation of 4.17%). The isotherms obtained at 30 °C and 40 °C are practically coincident and overlapped for aw below 0.40. Fermented cocoa beans presented a monolayer moisture content of 0.083 dry basis (d.b.) at 30 °C and this value decreases with increasing temperature. The net isostheric heats of desorption for fermented cocoa beans for the temperature range studied (30-60 °C) were estimated as a function of moisture content. The maximum net isosteric heat of desorption for fermented cocoa beans was estimated at around 13.51 kJ/mol corresponding to a moisture content value of 2.85%. The energy requirement for maintaining the moisture content low of 8.7% (d.b.) or 8% wet basis (w.b.) for safe storage of this product or for reducing the moisture content during drying was estimated at around 9.58 kJ/mol.
The general objective of this work is to contribute to the reduction of post-harvest losses of mangoes by the transformation into stable dried products.This research aims to determine the best storage conditions for dried mangoes.Thus, the water adsorption isotherms of mango slices dried under hot air were experimentally determined by the static thermogravimetric method at 25°C.Eight mathematical models from the literature were used (GAB, BET, Hasley, Henderson, Harking and Dura, Oswin, Chung and Pfost, Smith) to describe the hygroscopic behavior of dried mango slices.Regression analysis was performed using MatLab R2016a software to determine the coefficients, model parameters and statistical parameters of the smoothing.The results revealed that the equilibrium is obtained from 35 days for the two samples and the adsorption isotherms determined are of type II characterized by a sigmoidal shape.In addition, the three-parameter (GAB) model showed good agreement with the experimental data (r= 0.999 and 0.997 respectively for slices with thicknesses of 1cm and 1.5cm) at 25°C.The water content of the mono-molecular layer is 2.295% at 25°C for the 1cm slices and 2.289% at 25°C for the 1.5cm slices.The net isosteric heat of adsorption tends towards zero for high water contents (0.052KJ/mol at 44.472% water).The linearity between enthalpy (net isosteric heat) and differential entropy of adsorption shows their compensation.
The purposes of this study were to compare the modalities of the post-harvest practices of these two groups and to statistically identify the modalities responsible of non-quality (under grade) on the basis of results of Pareto chart and proportion of successes calculated for each modality. A survey about of modalities of post-harvest processing methods and about the quality of the beans obtained was conducted among producers of the largest producing region of Côte d'Ivoire. The collected data were analyzed by the chi-square test of concordance and the Pareto chart. The results show that there is no correlation between practice of the individual farmers and the farmers in cooperatives. Highly significant differences (p-value < 0.001) were observed in the number of brewing; the fermentation time; the materials of fermentation and drying impacting the quality of merchantable cocoa. Samples collected from farmers into cooperatives have fewer defects than those of individual farmers. Regarding the modalities of the post-harvest practice responsible of the under-grades, the results showed that the samples of farmers in cooperatives had fewer defects than those of individual farmers. Thus, obtaining a good quality cocoa beans must take into account the best modality at each step of post-harvest practices. However certain modality should be avoided. These are: the time breaking pods of one day; the absence of brewing during the fermentation; the time of fermentation less than or equal to three days and the time of drying less than or equal to two days.
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