Modelling Kinetics of Extruded Fish Feeds in a Continuous Belt Dryer

Feed is the major inputs in aquaculture production which affects the development growth of aquaculture in the African continent. Extruded fish feeds are dried to desire moisture content to increase the shelf life. Conventional method of drying fish feeds had gained attention recently in Nigeria in order to reduce high cost of producing fish feeds. However, this method is still grossly underutilized. Extrude floating fish feed was dried using continuous belt dryer at drying air temperature from 60°C to 100°C at an interval of 10°C, velocity of air using for drying from 0.8 m s-1 to 1.0 m s-1 at an interval of 0.1 m s-1 using a constant linear belt speed of 50 m s-1. Various moisture contents gotten at different conditions were changed to ratio of the dried extrudates moisture so as to obtain curves of drying by plotting the ratio of moisture against time. The dried extrudates behaviour was determined by fixing the drying curves with five well known models. Model with high determination coefficient and low reduced chi-square, low standard error, low value of least square and low standard deviation error (SEE) was used as best model. Midilli et al model was found suitable in describing the behaviour of extruded fish feed during drying. The temperature of air used for drying was discovered to have a major influence on the drying kinetics of the extruded fish feeds based on the conditions of this experiment.

Modelling Kinetics of Extruded Fish Feeds in a Continuous Belt Dryer

Feed is the major inputs in aquaculture production which affects the development growth of aquaculture in the African continent. Extruded fish feeds are dried to desire moisture content to increase the shelf life. Conventional method of drying fish feeds had gained attention recently in Nigeria in order to reduce high cost of producing fish feeds. However, this method is still grossly underutilized. Extrude floating fish feed was dried using continuous belt dryer at drying air temperature from 60°C to 100°C at an interval of 10°C, velocity of air using for drying from 0.8 m s-1 to 1.0 m s-1 at an interval of 0.1 m s-1 using a constant linear belt speed of 50 m s-1. Various moisture contents gotten at different conditions were changed to ratio of the dried extrudates moisture so as to obtain curves of drying by plotting the ratio of moisture against time. The dried extrudates behaviour was determined by fixing the drying curves with five well known models. Model with high determination coefficient and low reduced chi-square, low standard error, low value of least square and low standard deviation error (SEE) was used as best model. Midilli et al model was found suitable in describing the behaviour of extruded fish feed during drying. The temperature of air used for drying was discovered to have a major influence on the drying kinetics of the extruded fish feeds based on the conditions of this experiment.

DRYING KINETICS OF FISH (Clarias gariepinus) SMOKED WITH BIOGAS

This is aimed at studying the aeration kinetics of catfish (Clarias gariepinus) smoked directly with biogas. Five live fresh fishes (Clarias gariepinus) were obtained from Fishery and Aquaculture Technology Department in FUTA, Ondo State, Nigeria at the age of 4 months with average weight of 900g each. The fishes were killed, de-gutted, thoroughly washed with water, cut into pieces of 3cm length. The chunks were laid in a single layer on a mesh directly exposed to biogas flame obtained from bio-decomposition of poultry waste and the weight was being monitored at 15 minutes interval until constant weight was observed. The study showed that the time taken for drying of Clarias gariepinus to reach the humidity point of around 12.43% (db.) was two and a half hours. The drying data was subjected to 10 thin-layer drying models. The compared the performances of the models using the determination of coefficient (R2), reduced chi­square (x2) and root mean square error (RMSE) between the calculated and predicted moisture ratios. The results showed that Henderson and Pabis modified model (highest R2 and lowest x2 and RMSE of 0.998, 0.00021 and 0.01386 respectively) was found to satisfactorily describe the biogas drying curves of Clarias gariepinus.

Ultrasonic Pretreatment-Assisted Electrohydrodynamic Drying of Potato Slices

To investigate the drying characteristics and mechanism during electrohydrodynamic (EHD) drying with ultrasonic pretreatment, the ultrasonic pretreatment-assisted EHD drying method at different power values was used to carry out the drying experiment of potatoes. To carry out this study, potato slices were pretreated with different ultrasonic power values (150, 180, 210, 240, and 270 W) or without ultrasound for 30 min at 30°C. The corresponding voltage was 18 kV during EHD drying. The moisture ratio, drying rate, color, shrinkage, and rehydration rate of potatoes were determined. The microstructure of potatoes was analyzed using infrared spectroscopy and scanning electron microscopy. Eight mathematical models were used to fit the drying of potatoes. Results showed that, compared with the control group, the ultrasonic pretreatment combined with the EHD drying group had improved the drying rate of potato slices, which was different at varying ultrasonic power values. Ultrasonic pretreatment had a remarkable effect on the color of the potato but had little effect on the shrinkage rate. The maximum rehydration rate is 5.7704 at 180 W. The minimum and maximum values of effective moisture diffusivity (Deff) were 3.4070 × 10−7 m2/s and 4.1160 × 10−7 m2/s, respectively. The effect of ultrasonic power pretreatment on the microstructure of potato in the EHD drying process was significant ( p > 0.05 ). According to the statistical parameter evaluation, eight mathematical models could satisfactorily describe drying curves of potato slices dried under EHD with ultrasonic pretreatment, and the logarithmic model was best suited. This work provides a theoretical basis and practical guidance to further understand the parameter characteristics and mechanism of ultrasonic pretreatment combined with the EHD drying technology.

A Simple Water Retention Model Based on Grain Size Distribution

The Hunter valley region in NSW Australia is an area with a heavy coal mining presence. As some mines come to their end of life, options are being investigated to improve the topsoil on post mining land for greater plant growth, which may allow economically beneficial farmland to be created. This research is part of an investigation into mixing a mine waste material, coal tailings, with topsoil in order to produce an improved soil for plant growth. Implementing such a solution requires estimation of the drying path of the water retention curves for the tailings and topsoil used. Instead of a lengthy laboratory measurement, a prediction of the drying curve is convenient in this context. No existing prediction models were found that were suitable for these mine materials, hence this paper proposes a simple and efficient model that can more accurately predict drying curves for these mine materials. The drying curves of two topsoils and two tailings from Australian coal mines were measured and compared with predictions using the proposed model, which performs favorably compared to several existing models in the literature. Additionally, the proposed model is assessed using data from a variety of fine- and coarse-grained materials in the literature. It is shown that the proposed model is overall more accurate than every other model assessed, indicating the model may be useful for various materials other than those considered in this study.

The Use of Starch Drying Kinetics Curves for Experimental Determination of Its Specific Surface Area

The most popular method for the calculation of specific surface area is its determination from water vapour sorption isotherms. The study presented here has been designed for the purpose of optimisation and selection of the conditions of drying so as to allow the determination of specific surface area from plotted curves of the drying process. The results indicate that drying curves can be used as the basis for the determination of specific surface area, the values of which do not differ statistically significantly (α = 0.05) from those determined from isotherms of water vapour sorption (adsorption/desorption).

Optimal drying conditions for valorization of industrial apple pomace: Potential source of food bioactive compounds

Apple pomace contains a large amount of useful bioactive compounds that have wide application in the food industry. In this study the effect of drying temperature and pressure (high temperature 80 °C and low temperature 60 °C using a conventional oven and a combination of conventional plus vacuum drying oven) on the antioxidant capacity and phenolic compounds of apple pomace extract was investigated. For a combination of conventional and vacuum drying ovens, samples were first dried by a conventional oven to a moisture content of approximately 10% then vacuum dried to reach a final moisture content of 3–4%. After the drying processes, ethanolic extraction was performed and the amount of total polyphenol and the antioxidant capacity (FRAP) were evaluated to determine a best drying method. The drying curves were also determined. The drying temperature affects the duration of the drying, the rate of water loss, and the remaining amount of antioxidant compounds.

Research into kinetics of filtration drying of alcohol distillery stillage

The article describes the results of experimental studies on kinetics of the filtration drying of corn distillery stillage, which has previously proven its effectiveness in drying other crops and various dispersed materials. The experimental data are presented in the form of graphical plots describing the change of material moisture over time depending on the temperature of the drying agent (60, 70, 80 and 900С) and the layer height (40, 80, 120 and 160 mm). The obtained results are analyzed and the changes that occur on the filtration drying curves depending on the change in the material layer height and drying agent temperature are described. It is shown that the filtration drying time of alcohol distillery stillage increases with increasing the material layer height. It is determined that the drying potential remains constant at the same parameters of the drying agent. It is shown that the rate of moisture removal during the filtration drying does not depend on the material layer height. It is found that the average residual moisture of corn alcohol distillery stillage is 3.140.06 wt.%; this value satisfies industrial needs for an increase in its shelf life and the possibility of long-term storage and transportation.

Drying Kinetics and Modelling of Convective Drying of Kedondong Fruit

Kedondong is an underutilized fruit cultivated in a small scale in Malaysia and it contains nutrients that can be preserved through drying. The dried product can be sold as a premium fruit snack that could generate revenue for the producer. We studied the drying of peeled and unpeeled kedondong fruits using hot air (60-80°C). This study aims to investigate the drying kinetics (drying rates and effective diffusivities) of kedondong fruits and model the drying curves using thin layer models. Ten thin layer models were employed and solved using non-linear regression. Drying kinetics showed that only falling rate periods were observed, which implied that internal diffusion was the dominant mechanism for moisture release. Mathematical models showed that Modified Hii et al. (I) and (II) models were able to predict the drying curve well with the highest R2 (0.9992-0.9999), the lowest RMSE (8.0 x 10-4 - 2.5 x 10-3) and the lowest χ2 (4.0 ×10-5 - 2.0 x 10-4). Peeled samples showed higher effective diffusivities (average 3.2 x 10-11 m2/s) than unpeeled samples (average 2.7 x 10-11 m2/s). The activation energy was lower in peeled samples (25.8 kJ/mol) as moisture diffusion could occur more easily than unpeeled samples (32.1 kJ/mol). Results from this study provide kinetic information that can be used in scaling up of dryer and optimizing dryer performances.

Drying kinetics and thermodynamic analysis of tomato in a tunnel dryer

In this study, drying kinetics and thermodynamic analysis of tomato were conducted in a tunnel dryer. Drying experiments were performed at three temperatures (100, 115, and 130 °C) and an air velocity of 1.45 m/s. From the drying curves, only a falling rate period was observed. Under these conditions, a characteristic drying curve was determined. It is observed that at the 40 minutes of the drying process, the outlet gas enthalpy achieved a maximum value that is very close to the inlet value and remained constant until the end of the process. Entropy exhibited similar behaviour to enthalpy. The maximum value of the exergy efficiency curve corresponds to the maximum value observed within the drying rate curves. This maximum value represents the stage when the available energy is efficiently used in moisture removal. As the drying rate decreases the available energy is started to be less employed.