Cocoa Bean (Theobroma cacao L.)Drying Kinetics (original) (raw)

Study of Thin-Layer Drying Kinetics of Fermented Cocoa Beans (Theobroma Cacao L) Using Semi-Empirical Models: Determination of Effective Moisture Diffusivity and Activation Energy

International Journal of Innovative Research and Development, 2021

This study is all about of cocoa beans moisture content behavior and prediction, during drying and experimental determination of effective moisture diffusivity and activation energy of thin-layer. Experiments were carried out on fermented cocoa beans using an oven at 40, 45, 50, 55 and 60°C. Seven semi-empirical models based on the drying kinetics were used for the modeling. This work determined the effective moisture diffusivities and activation energy of cocoa beans using respectively a variable diffusivity model based on Fick's second diffusion law and Arrhenius standard equation. The aim was to obtain the evolution of moisture content in cocoa beans considering temperature, moisture content ratio and time. The results revealed and demonstrated the reliability of some theoretical models with natural drying for temperatures below 45 °C and others with convective hot-air drying for temperatures above 50°C. All of these models seemed to be the most appropriate for describing the type of drying of cocoa beans. Values of the apparent diffusion coefficient are between 2.33275 x 10-11 m 2 /s and 2.8561 x 10-11 m 2 /s. The effective moisture diffusivity increases as a function of the drying temperature and decreases as a function of the decrease in moisture content of the product. Values of Do and Ea were estimated respectively as 1.23 10-6 m 2 /s and 43.56 kJ/mol respectively, in accordance with material and literature. It was observed that, pH values of different cocoa beans samples were between 4.82±0.26 and 5.43±0.41.

Effect of Drying Temperature and Drying Air Velocity on the Drying Rate and Drying Constant of Cocoa Bean

Agricultural Engineering International Cigr Journal, 2009

The effect of some drying parameters and drying conditions of cocoa bean were determined. Three levels of temperatures (55, 70 and 81 °C) and three air velocity levels (1.3, 2.51 and 3.7 m/s) were used in the presented study. The moisture content of the cocoa bean used was 79.6 % (db). The heated batch cocoa bean dryer used in the evaluation was successful in drying thin layer of cocoa bean 5 cm deep at initial moisture content of 79.6 % (db) to 6 % (db), in 4-6 h of continuous drying at the above mentioned temperature range. The drying constant ranged from 0.009583 h -1 to 0.12666 h -1 under the above drying conditions. Coefficient of determination of 84.8 % was obtained with relationship of temperature and drying constant but when air velocity was incorporated it decreased to 80.9 %. The drying rate increased with increase in temperature and air velocity but decreased with time. The dryer can remove an average of 4.66 kg of water per day at 55-81 °C and air velocity of 1.3 m/s while at 2.51 m/s it can remove an average of 5.3 kg of water per day under the same drying conditions.

Convective drying of fermented Amazonian cocoa beans (Theobroma cacao var. Forasteiro). Experiments and mathematical modeling

Model Diffusion coefficient Transport phenomena Polyphenol Physical characteristics Sorption isotherms a b s t r a c t The general objective of this work is to contribute to the characterization and the mathematical modeling of the convective drying of fermented Amazonian cocoa beans (Theobroma cacao var. Forasteiro). A combined approach is used, including the analysis of the bean physical characteristics, the determination of the bean sorption isotherms, the realization of drying experiments in a convective dryer (for different operating conditions) and the development of a mathematical model, based on the different transport (heat and mass)

A mathematical model for predicting the drying rate of cocoa bean (Theobroma cacao L.) in a hot air dryer

2017

Development of a mathematical model for predicting the drying rate of a thin layer cocoa bean in a convective hot air dryer using dimensional analysis based on the Buckingham’s π theorem was presented. Results obtained showed that drying rate decreased as the moisture level reduced due to the increase in the intra-particle resistance to internal moisture migration of the cocoa beans. High coefficients of determination of 94.7%, 99.8% and 99.5% at temperatures of 60C, 70C and 80C respectively between the predicted and experimental values showed that the method was good. The model was validated with data obtained from an existing prototype thin layer convective dryer and there was no significant difference between the experimental drying rate and the predicted values at 5% level of significance. Two-tail test showed that t-calculated was less than t-tabulated at 5% degree of freedom, which indicated the suitability of the model at the studied temperatures. It was generally observed th...

Temperatures Dependent Drying Kinetics of Cocoa Beans Varieties in Air-Ventilated Oven

Frontiers in Heat and Mass Transfer, 2019

The drying kinetics of three varieties of cocoa beans (N38, F and WA) at 40, 50 and 60 degree centigrade was investigated experimentally. The three different varieties were dried using laboratory air oven UF Memmert and the moisture content determined according to AOAC standards. The results show that drying processes occur mainly in the range of the falling-rate period and the drying rates were observed to be faster at higher drying temperature. The effective diffusivities of the three cocoa beans varieties determined at 40, 50 and 60 degree centigrade ranged between 9.9269 x 10-11 and 4.4671 x 10-10 metre square per second. The predicted Arrhenius constant and activation energy were 2.47 x 10-10 metre square per second and 23.61 kilojoule per mole.

Comparative Analysis of the Drying Parameters of Theobroma cacao (Cocoa Beans) and Musa paradisiaca (Plantain)

Asian Journal of Research in Agriculture and Forestry

In order to prevent microbial spoilage and degradation responses during storage, agricultural products are typically dried to eliminate moisture from them. The removal of moisture is required for the preservation of this substance (drying). Under- or over-drying a product might result in loss through product damage. This work therefore focuses on the drying of two major crops grown by local farmers and agricultural companies; Musa paradisiaca and Theobroma cacao, obtained from a local farmer within Auchi, Edo state. The drying characteristics, including moisture content, moisture loss, and drying rates, were examined experimentally in this study at the university laboratory and Pax Herbal Clinic & Research Laboratories Ltd. This was obtained with the use of a locally fabricated cross and through circulation dryer for drying and a moisture analyzer to obtain moisture contents while taking into account temperature ranges between 40 and 80°C and time intervals from 5 to 40 minutes. The...

A Review of Cocoa Drying Technologies and the Effect on Bean Quality Parameters

International Journal of Food Science, 2020

Considering drying as a key farm-based, quality determining unit operation in the cocoa processing chain, this paper reviews recent studies in the drying methods and quality parameters of cocoa beans. Open sun, solar, oven, microwave, and freeze drying methods have been investigated at various levels in the drying of cocoa beans with objectives to improve the drying properties and final quality of cocoa beans. While an open sun dryer employs natural passive mechanisms, the solar drying methods can employ a combination of passive and active mechanisms. The oven, microwave, and freeze drying methods are fully active requiring electrical energy inputs. To improve drying rates in the open sun method, dryer materials and location of drying trays are the parameters optimized since the drying temperature depends on solar intensity. For solar dryers, materials, angles of elevation, heaters, and fans are manipulated to optimize energy absorption and drying parameters. For the oven and microw...

Drying of Cocoa Beans by Using Different Techniques

2017

Drying methods such as Tray dryer, solar cabinet dryer, Microwave oven and OYSD were used. Studies were undertaken to determine the effect of different drying methods on moisture content, drying time and quality. Experiments were conducted to determine most effective method of drying for suggesting to farmers. The results were analyzed to arrive at the most effective drying method. Based on experimental results, it was found that the time taken for drying of cocoa beans from an initial moisture content of 49.35%(w.b) to a final moisture content of 6.36 % (w.b) varied considerably right from 0.4 hours for microwave drying to 30 hours in OYSD. The time taken for drying in solar cabinet dryer and tray dryer was 16 h, 8 h respectively. The time taken in Tray drier was less for drying and there is a saving about 22 h of drying time as compared to OYSD. There is a saving about 14 h of drying time in solar cabinet dryer as compared to OYSD besides producing a better quality cocoa bean powd...

Modelling of Thin Layer Drying Kinetics of Cocoa Beans in a Microwave Oven and Sun

2015

The purpose of this work was to make a drying experiment of fermented cocoa beans concomitantly in the sunlight (using the experimental tray as a recommended device) and in a microwave oven (MO) to simulate the process by empirical models. The gradient method was used to estimate the coefficient of empirical models used in the study. The experimental data were adjusted from eleven equations published in the literature. The best suitable model was evaluated using the coefficient of determination (R²), reduced chi square (χ 2), the Root Mean Square Error (RMSE), the Sum Square Error (SSE) and the Mean Relative Deviation (MRD) in percentage (%) between the experimental and predicted values. The diffusion approach model was selected for the solar drying because this model presents the best statistics characteristics (0.991; 2.49 E-04; 0.036; 0.037 and 3.401%). For the microwave oven drying, high R 2 values (higher than 0.95), low values of χ 2 , RMSE, SSE and the MRD values below 10% ar...

Comparison of the drying behavior of fermented cocoa ( Theobroma cacao L . ) beans dried in a cocoa house , greenhouse and mechanical oven

Proceedings of the International Symposium on Cocoa Research (ISCR), Lima, Peru, 13-17 November 2017, 2017

The objective of this study was to compare the drying behavior of fermented cocoa (Theobroma cacao L.) beans dried in a traditional cocoa house replica and greenhouse-type dryer with that of beans dried in a mechanical cabinet oven at 40°C (drying for 8h with a rest period of 16h). Weight measurements were taken at the start of drying and at regular intervals during the drying process, and drying continued until there was no change in bean weight. Moisture content, water activity, pH and color attributes were measured at the start and at the end of drying. Sensory evaluation of the cocoa liquor was done on the dried samples. Initial moisture content of beans averaged 1.04 g H2O/g DM (50.9% wb). Final (equilibrium) moisture values attained after 11.4 days of drying in the cocoa house and the greenhouse and after 9.3 days of drying in the oven averaged 0.60, 0.70 and 0.50 g H2O/g DM (2.3-4.6 % wb), respectively. During the first 3 days of drying, the decline in moisture content was si...