Search

The microwave assisted vacuum frying (MWVF) of Durian cv. Monthong was performed to investigate the effect of microwave power levels (400,480, and 560 W) and ripening stages 1 Day, 2 Days, 3 Days, and 4 Days after harvesting) on the kinetics of the durian chips. The physio-chemical properties, the specific energy consumption (SEC) and product acceptability using sensory evaluation were also determined at 110 °C and absolute pressure of 8 kPa. At the higher microwave power, the frying time was reduced leading to a lower SEC. Moreover, it also resulted in decreasing oil absorption, decreasing shrinkage, and increasing porosity. In addition, more ripeness in durians led to longer frying time, increased oil uptake, but also produced a more porous structure and higher crispiness. Furthermore, using the 7-point hedonic scale test, the sensory evaluation revealed that the chips from the more ripened durian had the higher overall acceptability score. [ABSTRACT FROM AUTHOR]

Summary: This research evaluated the effects of process conditions on the physiochemical properties of vacuum‐fried durian chips. Ripened durians were sliced and fried at 90, 100, 110 and 120°C under 8‐kPa absolute pressure. From this study, microwave heating (MWH) during vacuum frying (VF) significantly reduced the frying time by 20% compared to VF (P < 0.05) with the effective moisture diffusivity for VF, pre‐treatment before vacuum frying (P+VF) and VF+MWH at 110°C determined to be 3.63 × 10−09, 4.30 × 10−09 and 4.84 × 10−09 m2 s−1, respectively. VF+MWH produced chips with significantly lower shrinkage, more yellowness (P < 0.05) and higher crispiness (consistent with the microstructure from scanning electron microscopy (SEM)). In addition, VF+MWH drastically decreased oil absorption by 10%, while P+VF yielded the lowest specific energy consumption (SEC). From sensory evaluation, the overall acceptability of VF+MWH chips rose from 5.83 to 6.07 (seven‐point hedonic scale), thus making the product fall into the 'Good' to 'Very Good' range. [ABSTRACT FROM AUTHOR]

A pilot-scale rubberwood dryer was constructed and injected with superheated steam and hot air to study the effect of the hybrid system on the drying rate and mechanical properties of the wood. A total of 300 pieces of rubberwood boards, each with dimensions of 1000 mm long × 76.2 mm wide × 25.4 mm thick, were stacked in 1.0 m × 1.0 m × 1.7 m (1.7 m3) pallet. The stack was impinged with alternating cycles of superheated steam and hot air. The time required for conventional drying was 168 hours, but the drying time for the hybrid system was only 64 hours, resulting in a 62% reduction. After being dried, the rubberwood boards were mechanically tested for static bending, compression strength, hardness, and shear strengths. From the mechanical tests, the hybrid drying system using superheated steam and hot air had no significant effect on the mean shear strength parallel-to-grain; however; the mean compression strength parallel-to-grain was reduced by 24.2% and the mean MOR by 21.4%. Nonetheless, the mean MOE was increased by 30.4% and the mean of hardness by 16.4%. [ABSTRACT FROM AUTHOR]

Spirulina is a cyanobacteria filled with therapeutic and nutritive properties that can be easily digested. It contains 71% protein by weight and a higher percentage of GLA (Gamma-Linolenic Acid) than any other plant. GLA has contributing properties of reducing blood pressure and blood cholesterol. After harvesting, the Spirulina is drained, sun-dried and dried in a convective oven. During the prolonged rainy season in Southern Thailand, convective drying alone can be very slow and energy consuming. Thus, this research investigated the effect of air-impingement technique on thin-layer drying of Spirulina. First, the effects of temperature (40, 50, and 60°C) and film thickness (2 and 4 mm) on the drying rate were obtained using a lab-scale dryer with a product capacity of 600 g. For an air velocity of 1 m/s, an increase in temperature up to 60°C resulted in an increase of the drying rate, while increasing the film thickness to 4 mm increased the drying time by 50%. In the second part of the study, a pilot-scale impingement dryer (1.2 m x 1.2 m x 1 m) was designed and constructed. The dryer consisted of 3 levels and can handle up 2.8 kg of fresh Spirulina per batch when arranged in a 2 mm layer film. The temperature distribution inside the dryer and the effect of air velocity (1.3 and 2.6 m/s) on the drying rate were investigated. From thermocouple measurements, the temperature deviation was less than 10% from top level to bottom level when compared to the average value. Moreover, using the specific moisture evaporation rate as the performance indicator, it was found that an air velocity of 2.6 m/s was more efficient than one of 1.3 m/s. [ABSTRACT FROM AUTHOR]

The effect of superheated steam vacuum drying (SSVD) on the drying time and mechanical properties of rubberwood was studied. Rubberwood boards with dimensions of 1000 mm × 76.2 mm × 25.4 mm were dried at 86.7-89.3 kPa vacuum pressure (14.6-12.0 kPa absolute) and temperatures of 60, 70, and 80°C. Superheated steam at 110°C was injected intermittently to relieve stress buildup in wood and eliminate cracking. The prong test was used to evaluate the initial acceptability of the dried wood and the mechanical properties of wood were measured. From this study, the total drying time was reduced from 168 h to less than 20 h (MC reduction from 0.80 to 0.06 db). In addition, compared to the reference values shown in the parentheses, the shear parallel-to-grain, the compression parallel-to-grain, the compression perpendicular-to-grain, the modulus of rupture (MOR), the modulus of elasticity (MOE), and the hardness for the optimum drying temperature of 70°C were 28.87 (11.0) MPa, 59.09 (32.0) MPa, 21.09 (5.0) MPa, 101.97 (66.0) MPa, 9838.5 (9240.0) MPa, and 6475 (4350) N, respectively. Thus, the vacuum-dried wood showed a 32% increase in hardness, a 12% increase in compression parallel-to-grain, and an 88% increase in shear parallel-to-grain. [ABSTRACT FROM AUTHOR]