Drying kinetics using superheated steam and quality attributes of dried pork slices for different thickness, seasoning and fibers distribution

Drying pork slice by superheated steam was proposed in this study. Sirloin muscle pork meat was sliced parallel and perpendicular to the fiber direction with thicknesses of 1 and 2 mm. The sliced samples were divided into two groups; unseasoned and seasoned pork, and were dried by superheated steam at a temperature of 140 °C. The experimental results showed that thicker pork slice needed more drying time, which led to more shrinkage, darker and redder dried product as compared to the thinner pork slice. Seasoning also extended the drying time of the seasoned pork slice and made the dried seasoned pork slice darker and yellower, but less in the values of hardness, toughness and shrinkage. Slicing directions did not have any significantly effect on drying time and color of dried pork slice. The parallel slice, however, lowered the values of hardness, toughness and shrinkage of dried pork.     

Modelling of moisture diffusion in pores of banana foam mat using a 2-D stochastic pore network: Determination of moisture diffusion coefficient during adsorption process

The purpose of this research was to determine the diffusion coefficient of moisture in the pores of banana foam mat using stochastic pore network. A 2-D pore network was used to represent the pore voids inside the banana foam sample and the moisture movement inside the individual pore segments was described by Fick’s law. To determine the moisture diffusion coefficient, the adsorption experiments were carried out with standard static method using saturated salt solutions. Two banana foam densities of 0.21 and 0.26 g/cm³ were used to adsorb the water vapour. The interactions between moisture and pore structure were illustrated using a 3-D pictorial representation of network concentration gradients in spaces with colour representing the moisture content. The network model described the experimental results relatively well. The diffusion coefficient of moisture in pores was in order of 10^-9${10}^{-9}$ m²/s which was nine times higher than the effective diffusion coefficient calculated from the continuum model. The value of moisture diffusion coefficient was dependent on the temperature and independent of the foam densities and the relative humidity, except for the diffusivity determined from the condition at higher relative humidity of 70%.     

Effect of temperature on drying characteristics and quality of cooked rice

A shorter drying time, together with acceptable product quality, is preferred in food processing. To accomplish this requirement, the present work was studied on the effect of temperature on drying kinetics and quality of cooked rice. The long grain-jasmine rice was chosen as a raw material. The experiments were carried out at temperatures of 50, 60, 80, 100 and 120 °C. Effective diffusion coefficient was determined experimentally using a method of slopes. An empirical equation was developed to describe the effective diffusion coefficient as a function of temperature and moisture content. The developed equation was utilized to predict moisture content as the drying progressed and the prediction agreed with the experimental result relatively well. For the quality, the drying temperature affected the color of cooked rice, but it insignificantly affected shrinkage and rehydration capability of dried cooked rice. As examined by scanning electron microscope, morphologies of cooked rice dried at temperatures were similar, but they were relatively different to that of freshly cooked rice, with slightly more porous material after processing.