Development and effectiveness of greenhouse type solar dryer for coriander leaves

Aim: Sun drying system is not able to provide the best drying performance and quality dried produce of leafy vegetables. To facilitate better options to the farmers, this study aims to develop and evaluate a cost-effective greenhouse type solar dryer to improve shelf stability of coriander leaves. Methodology: A greenhouse type solar dryer (5m x 3m x 2.3m) was developed with the provision of rigid frame, 200 µ UV stabilized LDPE glazing material, solar collector cum drying chamber, inlet air and outlet air openings. The dryer was evaluated for its performance, drying characteristics of coriander leaves and qualitative evaluation of dried product as compared to open sun drying. Results: The greenhouse type solar dryer performed well for coriander drying with increased level of temperature inside the dryer (42oC) and 24% reduced drying time as compared to sun drying (29oC).The loading capacity, efficiency, payback period and B:C ratio of the dryer were found to be 100 kg, 70.47 %, 1.26 yr and 1.79, respectively. The drying of coriander leaves occured mostly in falling rate period. Coriander leaves dried under the dryer possessed higher values of chlorophyll content (1.356 mg g-1 of tissue), ascorbic acid content (111.257 mg 100g-1), rehydration ratio (5.302) and coefficient of rehydration (0.762) than sun dried coriander leaves with the respective values of these quality parameters being 1.097 mg g-1 of tissue, 62.37 mg 100g-1, 4.715 and 0.689, respectively.

DRYING, COLOUR AND REHYDRATION CHARACTERISTICS OF ORANGE SLICES UNDER INFRARED RADIATION HEATING

The effect of different infrared (IR) powers on drying of orange slices was investigated in infrared dryer. The orange slices dried at 62, 74 and 88 W infrared powers and constant slice thickness of 6 mm. Results showed that drying, colour and rehydration characteristics of orange slices were greatly influenced by infrared power. The drying data were fitted with five mathematical models available in the literature. Based on the statistical tests applied to make an assessment, the model of Midilli and Kucuk was found to satisfactorily explain drying kinetics of orange slices for all drying conditions. The Fick’s diffusion model was used to calculate the effective moisture diffusivity (Deff) of orange slices. The value of Deff varied from 1.59×10-10 to 2.49×10-10 m2/s. It was found that the effective moisture diffusivities increased with increasing IR power. Activation energy was estimated by a modified Arrhenius type equation as 2.11 kW/kg. As the infrared power increased, the rehydration ratio was found to be reduced. Furthermore, with increase of infrared power, the values of a and DE increased, whereas the values of L, b and C decreased.

THE EFFECT OF DRYING TEMPERATURE, CUTTING TYPES, STORAGE DEGREE AND PERIOD ON PHYSICAL, CHEMICAL AND PHYSICOCHEMICAL PROPERTIES OF RED CAPIA PEPPER

This work was undertaken to evaluate the effects of different drying temperatures ​​(50, 60 and 70 oC) and cutting types (ring and cube) on the physical, chemical and physiochemical properties of red capia pepper during storage (14 days) both at room temperature and cold storage. Convective drying (CVD) at 50, 60 and 70 oC was applied to obtain dried red capia peppers. The effects of CVD on color values (L*, a*, b*), rehydration ratio, selected chemical properties (dry matter, pH and titratable acidity) and bioactive compounds (total phenolic content and antioxidant capacity) of thirteen dried red capia peppers were compared. The samples dried at 60 oC in ring forms under cold storage (6R-CD samples) showed the highest dry matter, pH, titratable acidity and rehydration ratio (87.06%, 5.69, 807.15 mg citric acid/100 g, 6.72%, respectively). The closest L*, a*, b*values to the fresh pepper samples were achieved for 6R-CD samples (L*:29.87, a*:12.83, and b*:17.03). In addition, 6R-CD samples resulted with highest antioxidant capacity and total phenolic content in all storage times.

Influence of vacuum microwave drying parameters on the physicochemical properties of red beetroots

In recent years, the consumption of red beetroots has increased significantly due to its good taste, high nutritional value and abundant active compounds. Red beetroot is prone to spoilage due to its high moisture content, making it perishable. Vacuum microwave drying is a gentle drying method by inducing fast water evaporation from food products at low temperature, which can improves the product quality. The objective of this study was to investigate the effects of vacuum microwave drying parameters, including microwave power (500, 1000, and 1500 W) and vacuum degree (50, 70, and 90 KPa), on the physicochemical properties (drying time, rehydration ratio, color change, and contents of betalain and total phenolic) of red beetroots. The results showed that microwave power and vacuum degree had significant effects on the physicochemical properties of red beetroots. All the red beetroots after vacuum microwave drying had higher lightness (L*), lower redness (a*) and yellowness (b*) than that of fresh red beetroots. The drying time, rehydration ratio, betacyanin content and betaxanthin content of red beetroots decreased significantly with the increase of microwave power (P < 0.05), while the rehydration ratio, color parameters (a*, b*, and chroma values), betacyanin content and betaxanthin content of red beetroots significantly increased with the increase of vacuum degree (P < 0.05). Compared with other microwave powers, the red beetroots dried at 500 W showed longer drying time, higher rehydration ratio, more yellowish hue, and higher contents of betacyanin and betaxanthin. The lowest values of total color difference (∆E) and hue angle (H°) of dried red beetroots were obtained at microwave power of 1500 W. The dried red beetroots obtained at 90 KPa had the shortest drying time, the highest rehydration ratio, the best color, and the highest contents of betacyanin and betaxanthin. Meanwhile, the red beetroots dried at 50 KPa had the highest total phenolic content (12.47 ± 0.09 mg GAE/g). Based on the physicochemical properties of red beetroots, vacuum microwave drying at low microwave powers and high vacuum degree appears to be a suitable method for drying red beetroots.

Pre-dehydration treatments and quality of processed potatoes during storage

ABSTRACT The aim of this work was to study pre-dehydration treatments to maintain consumption quality of processed potatoes (Solanum tuberosum) over a long storage period. Tubers of the cultivars Asterix, Macaca and Agata were cut into cubes and submitted to the following pre-dehydration treatments: water (control), blanching, and blanching with different doses of sodium metabisulfite. Sulphur dioxide residue and microorganism detection were determined right after the dehydration process was completed. Water activity, color, rehydration ratio, cooking time and rehydration ratio after cooking were determined at the beginning and after one and two years of storage. Blanching, cultivar and storage affected rehydration ratio, an important parameter used to measure the quality of dehydrated products. Tubers with higher dry mass content resulted in lower water activity and rehydration ratio, longer cooking time and higher rehydration ratio after cooking than those with lower dry mass. The combination of blanching with sodium metabisulfite improves product quality, reduces microbial load, enhances dehydration rate and prevents oxidation and browning reactions during processing and storage. The effects of the structural damages of pre-dehydration and dehydration treatments on the rehydration ratio and the rehydration ratio after cooking increase with storage of processed potatoes.

Drying kinetics and quality characteristics of daylily dried by mid-infrared

Industrially, the use of far-infrared (FIR) as a heat source for drying daylily presents some issues, such as high energy consumption and large loss of nutrients. The use of mid-infrared (MIR) was performed to study the drying of daylily to explore its advantages, with the FIR drying as a comparison. Drying models were established by the drying kinetics, and the changes of nutrition, rehydration ratio (RR) and water migration pattern were researched. The results showed the best-fitting drying model was the Modified Henderson and Pabis model. Under the same temperature, compared with FIR drying, the drying time of MIR drying was shortened by 50%, the effective moisture diffusivity (D eff) was increased by 103%, the drying activation energy (E a) was reduced by 10%, the reducing sugar and ascorbic acid retention rate was increased by 13.9% and 9.7%, respectively. The MIR drying had better RR and water migration characteristics.

Physical quality analysis of drying beluntas leaves (Pluchea indica L.) using variations of drying methods

Beluntas leaves are medicinal plants with pharmacological effects, such as antioxidant, antidiarrheal, antidiabetic, and antibacterial. Drying is one of the processes before the beluntas leaves are consumed. However, drying could degrade the quality of beluntas leaves. This research aims to investigate the impact of drying conditions on the physical qualities of dried beluntas leaves. Beluntas leaves with a moisture content of 83-90% were dried using drying methods, namely the greenhouse effect dryer (ERK), cabinet dryer (CD) at 40, 50, 60, and 70°C, and freeze dryer (FD) at 35, 45, and 55°C. The physical parameters measured were moisture content, color, shrinkage, rehydration ratio, and bulk density. The results showed that the final moisture content of the dried beluntas leaves were 8.40; 4.92-10.70; 4.73-6.77%w.b for ERK, CD, and FD, respectively. Page’s model was suitable for explaining the changes in moisture ratio during the drying process (R 2 = 0.9934 − 0.9999). The freeze-drying method can preserve the leaves’ color and obtain the lowest moisture content with a low drying temperature compared to other methods. Freeze-dried beluntas leaves also exhibited the highest rehydration ratio, which was 2.03 – 2.25.

The effect of pre-drying treatments on the quality of dehydrated ground beef

Dehydrated ground meat is widely used as an ingredient in various instant products. This study was aimed to investigate the effect of pre-drying treatments on the physicochemical properties of dehydrated ground beef. The experimental design used a completely randomized design of 3 x 3 factorial, with 3 grinding times (1, 3, and 5 minutes) and 3 cooking methods (steaming, pressure cooking/presto, and roasting). The beef was sliced, milled and cooked according to the treatments, frozen for 24 h, then dried by using an oven drier at a constant temperature of 60°C for 3 h, and finally powdered. The physicochemical properties of dried ground beef were determined including the yield, particle size distribution, rehydration ratio, hygroscopicity, color, moisture content, and fat content. Results showed that the presto method produced the highest moisture content of the cooked beef. Longer grinding time increased the particle passed mesh-6, rehydration ratio, and color, but decreased the final moisture content and fat content. Grinding time of 5 minutes with pressure cooking was selected as the best treatment to prepare dried ground meat. This treatment had a yield of 22.26%, moisture content of 3.38%, rehydration ratio of 3.25, the hygroscopicity of 6,13%, lightness of 53.62, value ‘a’ of 5.52, value ‘b’ of 10.21, and fat of 6.36%.

Effect of microwave, infrared, and convection hot-air on drying kinetics and quality properties of okra pods

Okra pods were dried using the following drying regimes; microwave (MWD), infrared (IRD) and convective hot-air drying (CHD). The objective of this investigate was to report the influences of drying methods on okra quality under different drying conditions. Data analysis showed that rehydration ratio and colour change increased with increase in drying air temperature and air velocity while specific energy consumption and shrinkage ratio decreased with increase in drying air temperature under (CHD). The rehydration ratio and colour of dried okra increased with increase in both infrared intensity but it also increased with a decrease in air velocity under (IRD). In the MWD method, drying time, specific energy consumption and shrinkage ratio decreased with increases in microwave power while the rehydration ratio and colour increased. Optimum drying period, specific energy consumption, colour, shrinkage and rehydration ratio were obtained for microwave drying. The model of Midilli et al. is the greatest for describing the drying curves of okra under all the drying processing conditions.

Nutritional Content and Characteristics of Pumpkin Cream Soup with Tempeh Addition as Supplementary Food for Elderly

An increase in the number of elderly people indicates a higher life expectancy. However, this is also a new challenge since the elderly tends to have age-related diseases, thus the physical, psychological, and sensory disorders that will affect their nutritional status. The development of geriatric foods such as cream soup made from pumpkin and tempeh is considered to be the solution to prevent this situation. This study used a factorial randomized design, containing processing methods (fresh and instant) and the addition of tempeh (0%, 75%, and 100%). Sensory evaluation (rating and ranking test), physical characteristics (pH, yield, rehydration, and viscosity), nutritional analysis (proximate, crude fibre, dietary fibre, vitamins B6 and B12, and β-carotene content), and acceptance analysis of cream soup fresh and instant were examined. Physical characterization revealed that the product had a pH of 5.4–5.7, a viscosity of 1250–2190 cP, a rehydration ratio of 5.51–6.47 g mL-1, and a yield of 19.44%–26.9%. The result of sensory evaluation showed that the processing method and tempeh addition had a significant effect ( p < 0.05 ) on the product acceptance. This also affects the nutritional value, in which fresh products had higher nutritional value than the instant product, and products with tempeh had higher ash, protein, dietary fibre, and vitamin B12 than products without tempeh. Based on this analysis, the instant cream soup with 75% tempeh is the best formula. In one portion size (50 g), instant cream soup with 75% tempeh met 10% or more of the Indonesian recommended dietary allowance (RDA) for the elderly in terms of protein, carbohydrates, fat, energy, dietary fibre, vitamin B12, vitamin B6, and vitamin A, so it can be recommended as a complementary food for the elderly.