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One of the most crucial factors in determining the consumer acceptability of processed or non-processed food products is their textural characteristics. Textural properties of food items can be created during processing by different techniques, one of which is drying. Drying which is one of the most widely used preservation methods of food products can extend their shelf life and generate unique sensory characteristics. The complicated process of drying is characterized by massive deformations while simultaneously transferring heat and moisture. Texture parameters of the dried food products vary depending on the type of dried food product (fruit and vegetables, grain and cereals, meat and marine), including the final volume, porosity, crust formation, and bulk density. Thus, this review focused on the examination of the textural characteristics of dried food items, the impact of the drying process, and the applied method on textural parameters. This study has also investigated the importance of pretreatment methods in improving the textural properties and quality of dried products. Furthermore, this review also considers the importance of modeling for texture prediction, discussing the different modeling approaches and their principles and applications. Recent applied nondestructive methods for textural analysis have been discussed in terms of application and performance. [ABSTRACT FROM AUTHOR]

In this study, the finite volume method was used to evaluate the thermal performance of a flat-plate solar collector used to dry agricultural crops. A 3D numerical model was created and used to predict the outlet air velocities and temperatures for three inlet air velocities. When compared with experimental measurements, the numerical predictions showed good agreement under all testing conditions. Then, the numerical model was used to predict the internal airflow and heat transfer characteristics of the collector. The internal baffles were found to increase the dwell time and efficiency but also promote flow separation, which resulted in flow loss. In addition, the collector has a transparent cover that results in a substantial heat loss, which can be mitigated by adding a vacuum gap between the flow inside the collector and the cover. Increasing the flow rate increased the heat loss and decreased the heat uptake, which decreased the temperature difference between the inlet and outlet of the collector. Because the heat was lost through long-wavelength radiation via the transparent cover and sidewalls, coating the absorber plate with black matte paint to increase the solar radiation absorption coefficient did not improve the drying performance. [ABSTRACT FROM AUTHOR]

In this study, coriander leaves were subjected to three different drying techniques; direct sun, shade, and using an indirect solar dryer. In the developed dryer, hot air obtained from a black-body solar collector was pushed by a blower powered by a solar panel, and sent to the drying chamber with multiple trays for thin-layer drying. Experiments were conducted for summer and winter seasons, and temperature and relative humidity variations in the drying chamber were measured using a data acquisition system. Indirect solar dryer performance was evaluated and compared with sun drying and shade drying for drying kinetics, moisture diffusivity, and product quality. The drying rate curves show a linear falling rate throughout the drying process. The drying kinetic models are well-fitted with the Midilli and Kucuk thin-layer drying model. The effective moisture diffusivity of the dried coriander shows a decreasing trend, sun drying (2.63 × 10−10 m2/s and 1.05 × 10−10 m2/s) followed by solar dryer (1.31 × 10−10 m2/s and 6.57 × 10−10 m2/s), and shade drying (6.57 × 10−11 m2/s and 3.94 × 10−11 m2/s) for winter and summer seasons, respectively. Green color changes from −7.22 to −0.056, −7.22 to 3.15, and −7.22 to −0.35 in indirect solar, direct sun, and shade drying, respectively. The hue angle and Chroma are reduced by 12% and 32% in indirect solar drying, respectively. The total phenol content (TPC) value increases with drying, with summer showing the highest values (365 to 852 mg caffeic acid/100 g dry weight) while the antioxidant capacity reaches 3.41 and 3.53 in winter and summer, respectively from 0.22 μmol Trolox/g dry matter of fresh leaves. [ABSTRACT FROM AUTHOR]

Fish drying is one of the traditional methods where the fishermen land their catch on the beaches for drying traditionally under sun for several days. Dried fish provides valuable and economical sources of animal protein. The quality of dried fish is significantly influenced by the presence of microorganisms. Therefore, this study aims to determine the physical quality changes in anchovy under three different solar drying methods which are open sun drying (OSD), solar greenhouse tunnel dryer (GTD), and forced convective solar dryer (FCD) and to verify the chemical and microbial contamination in solar-dried anchovy. About (20 kg) of fresh anchovy were taken for experiments. Quality analyses were conducted in the samples before, during, and after drying. The parameters analyzed included three main analyses which are physical, chemical, and microbial analyses. The drying rate was higher in GTD compared to the two other methods. Moisture content, drying rate, and moisture ratio were significantly affected by drying methods. GTD required less time (6 hr) to dry anchovies compared to other drying methods (9 hr time). The highest reduction in lightness is in GTD dried anchovies followed by FCD and OSD. The drying methods and drying time statistically affect the lightness (L) of dried anchovies (p ≤ 0.05). The water activity of solar-dried anchovies was 0.3. Experimentally dried anchovies were found to have lower microbial count compared to the dried fish quality standards. The total viable count (TVC) in fresh anchovy was 6.44 log CFU/g compared to the greenhouse tunnel dryer 2.90 log CFU/g, open sun dryer 4.16 log CFU/g, and forced convective dryer 4.19 log CFU/g anchovies. Water activity and moisture content did not affect total viable count (TVC) significantly, but it affects total fungal count (TFC) (p ≤ 0.05). There was a significant difference on Krusal Wallis between the samples of three methods of drying and a fresh one on the water activity, ash content, and fat content (p ≤ 0.05). [ABSTRACT FROM AUTHOR]

The techno-economic performance analysis of biogas production, power generation and recovery of heat for drying of agricultural products for a Nigerian rural community is explored through process simulation. In this work, biogas generation from a 10.33MT/day cattle market waste was fed into a 72kW e CAT internal combustion engine and the model has been developed using Aspen HYSYS R process simulator. Simulation results shows that about 191.63MT per annum of tomato can be dried with the recovered heat while heat recovery for anaerobic digestion and drying of agricultural products increases the system's heat efficiency from 25.6% to 58.4%. The results also show that, with the current electricity tariffs for remote areas being charged at USD 0.02/kWh and Feed-in Tariffs (FITs), NPV is positive and the payback period is 3.2 years. However, system less than 1MW is not currently captured in Nigeria's FITs system while the economic indices are negative without FITs. Effects of interest rate regimes on economic indices is also explored as such system could be farm based and entitled to loan from the Nigerian Agricultural Development Bank, Bank of Industry and Commercial banks with interest rates 7%, 9% and 20% respectively. The results presented in this paper increased research knowledge on application of biogas CHP in Nigerian rural communities especially on integration of energy generation with processing of agricultural products [ABSTRACT FROM AUTHOR]

Highlights • A review of the sustainable drying of agricultural products is presented and detailed. • Hybrid drying systems are promising and competitive when compared with others. • Modelling software that integrates energy source plays a significant role in hybrid system optimisation. • Biomass powered CHP system may be a good solution to sustainable food drying in rural areas. Abstract Quests for sustainability, food security and need to decouple food prices from fluctuating prices of finite fossil fuels are the drivers to sustainable processing and storage of agricultural products. Farming predominantly takes place in rural areas where conventional energy technologies may either be expensive or sometimes technically infeasible to be obtained. This necessitates deployments of renewable energy technologies to remote areas for sustainable power generation, cooling and drying of agricultural product. Renewable systems e.g. solar dryers, solar hybrid dryers, combined power and drying system take leading roles in sustainable drying of farm produce. A number of research studies have been carried out in the past one decade, which mainly concentrate on modelling, simulation and experiment of different sustainable drying techniques. Therefore, this paper aims to present a state of the art review on the contributions of combined power and drying, application of phase change materials and hybrid drying systems with regard to agricultural products. Based on this comprehensive summarization, it is indicated that deployment of biomass powered combined heat and power systems might be a good solution to post-harvest wastes since both electricity and heat for drying of agricultural products can be simultaneously obtained. [ABSTRACT FROM AUTHOR]

Abstract: An infrared dryer was developed and infrared radiation thin layer drying of onion slices was carried out at infrared power levels of 300, 400 and 500W, air temperatures of 35, 40 and 45°C and air velocities of 1.0, 1.25 and 1.5m/s. The drying occurred in the falling rate of drying period. Drying rate increased with increase in infrared power at a given air temperature and velocity and thus reduced the drying time. The drying time increased with increase in air velocity at a given infrared power and air temperature because of the increased cooling effect at the surface of the product. Eight available moisture-ratio models were fitted to the drying data. Page’s model had a higher correlation coefficient and low chi-square value and thus predicted drying behaviour of the onion slices more accurately. [Copyright &y& Elsevier]