scholarly journals Modelling the Thin-Layer Drying Kinetics of Marinated Beef during Infrared-Assisted Hot Air Processing of Biltong

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Francis C. Muga ◽  
Moses O. Marenya ◽  
Tilahun S. Workneh

Biltong is a dried meat product that is widely consumed in South Africa. The marinated meat is traditionally dried under ambient winter conditions while commercial biltong producers use hot air driers. Hot air drying is time-consuming and energy-intensive. A combined infrared and hot air drying (IRHAD) is an alternative method of drying meat during biltong processing. The aim of this study was to establish the effect of the infrared (IR) power, the temperature, and velocity of the drying air on the drying kinetics of marinated beef and subsequently select the best thin-layer drying model for IRHAD during biltong processing. Marinated beef samples were dried at IR power levels of 500, 750, and 1000 W; drying air temperatures of 30, 35, and 40°C; and air velocity of 1.5 and 2.5 m∙s-1. Results indicate that increasing the IR power and the drying air temperature increased the IR emitter temperature and the core temperature of the marinated beef sample. Consequently, increasing the drying rate thus reduced drying time. The air velocity had an inverse relationship with the IR emitter temperature, the core temperature of the marinated beef sample, and the drying rate. The drying process was characterised by a rising rate period in the first half an hour, followed by a falling rate period which implies that moisture transport occurred partly by surface evaporation and predominantly by diffusion. The effective moisture diffusivity ranged from 4.560 × 10 − 10 to 13.7 × 10 − 10   m 2 ∙ s − 1 , while, the activation energy ranged between 40.97 and 59.16 kJ∙mol-1. The IRHAD of marinated beef during its processing to biltong was best described by the two-term model since it had the highest R 2 (0.9982-0.9993) and the lowest RMSE (0.0062-0.0099). The power level of the IR emitter of 1000 W combined with a drying air temperature and velocity of 40°C and 1.5 m∙s-1, respectively, showed the highest improvement in the drying kinetics and the lowest drying time of 5.61 ± 0.35 hours; hence, it is recommended as a possible drying alternative for the processing of biltong.

The study is aimed experimentally and compared with the theoretical results of drying kinetics of Nagpur orange fruit dried in a hot air electrical dryer. Orange fruit is highly perishable and needs to be consumed or processed immediately after harvest. Drying or dehydration is one of the most practical methods of preserving food products. Therefore, thin layer drying characteristics of falling rate of Nagpur orange are determined experimentally under different conditions of drying air temperatures, relative humidity and air velocities for different moisture contents. Thin layer models like Wang and Singh, Page and Henderson have been compared with Experimental results. The knowledge of drying kinetics helps for identification of exact drying time and air flow velocity for different moisture content. Here drying operation is carried out at a velocity of 1m/sec and 1.25 m/sec for different temperature of 55°C, 65°C and 75°C. This analysis reveals that drying temperature has a more significant effect on moisture removal while velocity has the least effect. Drying rate is found to increase with the increase in drying temperature and reduce with drying time. Experimental data is statistically correlated by plotting the drying characteristics curve. The analysis reveals that Wang and Singh's model is a better model to explain the drying behavior of Nagpur Orange fruit (R2=0.9888).


2021 ◽  
Vol 13 (1) ◽  
pp. 59-72
Author(s):  
Javid Ghasemi ◽  
Mehdi Moradi ◽  
Sayed Hossein Karparvarfard ◽  
Mohammad Taghi Golmakani ◽  
Amin Mousavi Khaneghah

The thin-layer drying kinetics of lemon verbena leaves were studied by using a solar cabinet dryer at air tempera-ture (at three levels of 30, 40, and 50°C), air velocity (at three levels of 2, 2.5, and 3 m/s), and mesh tray size (3, 6, and 10 mm). A completely randomized factorial design was used to analyze the effect of independent factors on drying time and essential oil yield. Results showed that all experiments have shorter drying time and higher essen-tial oil content than the shade-drying method. Also, the best drying conditions that led to an optimal essential oil yield (1.73 mL/g DM) involved a lower temperature (30°C) and velocity (2 m/s) and a mesh size of 10 mm. A good adaptation between the experimental and the predicted moisture content was observed, whereby the statistical criteria of R2, root mean square error, and k2 were calculated as 0.99, 0.08, and 0.01, respectively. Practical applicationsIn the current study, the effect of different drying states such as air velocity and drying temperature was studied on the drying behaviors and essential oil contents of lemon verbena leaves. The obtained results can lead us to a suitable drying condition that can be used in the subsequent designation of systems. Also, a mathematical model for the pre-diction of the leaves’ drying kinetics was constructed and evaluated, which could be approached in the drying systems.


Author(s):  
Dan Huang ◽  
Yuchao Tao ◽  
Wei Li ◽  
S. A. Sherif ◽  
Xiaohong Tang

Abstract The heat transfer characteristics and kinetics of Camellia oleifera seeds under hot-air drying were investigated at different temperatures (40, 60, and 80 °C) and loading densities (0.92, 1.22, and 1.52 g/cm2) with a constant air velocity of 1 m/s. Twelve common drying kinetic models were selected to fit the experimental data. The most suitable model was chosen to describe the hot-air drying process of C. oleifera seeds and help in its optimization. The results showed that the drying temperature has a significant influence on the hot-air drying characteristics of C. oleifera seeds. As the drying air temperature increases, the drying time decreases. The effect of the loading density on the drying characteristics of C. oleifera seeds is much smaller than that of temperature. With the increase in the loading density, the drying time slightly increases. The hot-air drying curve of C. oleifera seeds consists of a very short acceleration rate period at the beginning and a long falling rate period, indicating that the drying of C. oleifera seeds is mainly controlled by the diffusion of moisture inside the material. An effective moisture diffusion coefficient of C. oleifera seeds was estimated to range from 0.81256 × 10−9 to 3.28496 × 10−9 m2/s within the temperature range studied. The average activation energy was 28.27979 kJ/mol. The logarithmic model was found to be the best model to describe the kinetics of hot-air drying of C. oleifera seeds.


Foods ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2362
Author(s):  
Lin Zhu ◽  
Xianrui Liang ◽  
Yushuang Lu ◽  
Shiyi Tian ◽  
Jie Chen ◽  
...  

This paper studied the effects of freeze-thaw (FT) cycles on the juice properties and aroma profiles, and the hot-air drying kinetics of frozen blueberry. After FT treatment, the juice yield increased while pH and total soluble solids of the juice keep unchanged. The total anthocyanins contents and DPPH antioxidant activities of the juice decreased by FT treatments. The electronic nose shows that FT treatments significantly change the aroma profiles of the juice. The four main volatile substances in the fresh juice are (E)-2-hexenal, α-terpineol, hexanal and linalyl formate, which account for 48.5 ± 0.1%, 17.6 ± 0.2%, 14.0 ± 1.5% and 7.8 ± 2.7% of relative proportions based on total ion chromatogram (TIC) peak areas. In the FT-treated samples, the amount of (E)-2-hexenal and hexanal decreased significantly while α-terpineol and linalyl formate remained almost unchanged. Repeated FT cycles increased the ethanol content and destroyed the original green leafy flavor. Finally, the drying kinetics of FT-treated blueberries was tested. One FT treatment can shorten the drying time by about 30% to achieve the same water content. The Deff values of the FT-treated sample are similar, which are about twice as large as the value of the fresh sample. The results will be beneficial for the processing of frozen blueberry into juice or dried fruits.


2020 ◽  
Vol 4 (1) ◽  
pp. 44
Author(s):  
Mukesh Guragain ◽  
Pranabendu Mitra

The preservation of perishable horseradish crop is essential to increase the shelf-life and supply year-round. Hot air-drying method is commercially viable for preserving fruits and vegetables. However, drying conditions such as drying temperature affect the drying kinetic and the final quality of dried products. It is necessary to understand how drying temperature and blanching affect the drying kinetics of horseradish for the prediction of the right drying conditions. The objective of this study was to investigate the hot air-drying kinetics by fitting commonly used five empirical models to establish right hot air-drying conditions for drying of horseradish. The unblanched (control, C) and blanched (B) horseradish slices were dried at 50, 70 and 85℃ until reaching to an equilibrium moisture content (db). The moisture reduction data were collected at certain intervals and the moisture content data were converted to moisture ratio (MR). The MR data were used to predict the drying kinetics of horseradish drying using five empirical models. The results indicated that drying kinetics followed the constant drying rate period and falling rate period for all three drying temperatures. The five tested models were able to predict the drying kinetics with R2 (0.96-0.99) and RMSE (0.01-0.06) depending on the models and blanching. However, diffusion approach model was the best fitted model securing the highest R2 and the lowest RMSE. The findings of this research are expected to be significantly important for horseradish drying effectively.


Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 202
Author(s):  
Ivan Pavkov ◽  
Milivoj Radojčin ◽  
Zoran Stamenković ◽  
Krstan Kešelj ◽  
Urszula Tylewicz ◽  
...  

This study aimed to determine the effects of osmotic dehydration on the kinetics of hot air drying of apricot halves under conditions that were similar to the industrial ones. The osmotic process was performed in a sucrose solution at 40 and 60 °C and concentrations of 50% and 65%. As expected increased temperatures and concentrations of the solution resulted in increased water loss, solid gain and shrinkage. The kinetics of osmotic dehydration were well described by the Peleg model. The effective diffusivity of water 5.50–7.387 × 10−9 m2/s and solute 8.315 × 10−10–1.113 × 10−9 m2/s was calculated for osmotic dehydration. Hot air drying was carried out at 40, 50, and 60 °C with air flow velocities of 1.0 m/s and 1.5 m/s. The drying time shortened with higher temperature and air velocity. The calculated effective diffusion of water was from 3.002 × 10−10 m2/s to 1.970 × 10−9 m2/s. The activation energy was sensitive to selected air temperatures, so greater air velocity resulted in greater activation energy: 46.379–51.514 kJ/mol, and with the osmotic pretreatment, it decreased to 35.216–46.469 kJ/mol. Osmotic dehydration reduced the effective diffusivity of water during the hot air drying process. It also resulted in smaller shrinkage of apricot halves in the hot air drying process.


Author(s):  
Amir Hossein Mirzabe ◽  
◽  
Gholam Reza Chegini ◽  

Sunflower seeds and oil in food and agricultural processing are of great importance. Dried sunflower petals are the most important parts of the sunflower plant that have economic value. Thin-layer drying experiments were performed in a laboratory scale hot-air dryer. The results indicated that with increasing drying temperature and air velocity, time of drying reduces and in most cases, the logarithmic model had the best performance for modeling the drying kinetics. The calculated values of the effective moisture diffusivity varied from 3.16627 ×10-13 to 1.32860 ×10-12 m2 s-1 and the values of the activation energy for air velocities of 0.4 and 0.8 m s-1 were equal to 51.21 and 42.3 kJ mol-1, respectively. Also, to verify whether the production and sale of sunflower petals can be cost effective, economic analysis was done. This analysis showed that drying of sunflower petals is profitable process and the generated revenue can even surpass the revenue from the sale of sunflower seeds.


2007 ◽  
Vol 79 (4) ◽  
pp. 1460-1466 ◽  
Author(s):  
A. Vega ◽  
P. Fito ◽  
A. Andrés ◽  
R. Lemus

Foods ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 101 ◽  
Author(s):  
Senadeera ◽  
Adiletta ◽  
Önal ◽  
Di Matteo ◽  
Russo

Drying characteristics of persimmon, cv. “Rojo Brillante”, slabs were experimentally determined in a hot air convective drier at drying temperatures of 45, 50, 55, 60, and 65 °C at a fixed air velocity of 2.3 m/s. It was observed that the drying temperature affected the drying time, shrinkage, and colour. Four empirical mathematical models namely, Enderson and Pabis, Page, Logarithmic, and Two term, were evaluated in order to deeply understand the drying process (moisture ratio). The Page model described the best representation of the experimental drying data at all investigated temperatures (45, 50, 55, 60, 65 °C). According to the evaluation of the shrinkage models, the Quadratic model provided the best representation of the volumetric shrinkage of persimmons as a function of moisture content. Overall, higher drying temperature (65 °C) improved the colour retention of dried persimmon slabs.


Author(s):  
Monica Premi ◽  
Harish Sharma ◽  
Ashutosh Upadhyay

Abstract The present study examines the effect of air velocity on drying kinetics of the drumstick leaves in a forced convective dryer. The drumstick leaves were dried in the temperature range of 50–800 C, at different air velocity (Dv) of 0.5 and 1.3 m/s. The results indicated that drying temperature and air velocity are the factors in controlling the drying rate. Experimental data obtained for the samples for color, drying rate and drying time proved that air velocity of 1.3 m/s yielded the product superior in terms of both quality and energy efficiency as compared to the samples at 0.5 m/s. Activation energy for drumstick leaves dried with air velocity, 0.5 and 1.3 m/s was 12.50 and 32.74 kJ/mol respectively. The activation energy relates similarly with the effective moisture diffusivity which also increased with increase in air velocity and temperature.


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