Showing papers by "Chung Lim Law published in 2016"

Drying kinetics and evolution of the sample's core temperature and moisture distribution of yam slices (Dioscorea alata L.) during convective hot-air drying

Abstract: In the present work, the drying kinetics and evolution of sample's core temperature and moisture distribution of yam slices during convective hot-air-drying were investigated. In terms of drying kinetics, the effect of drying temperature (50, 55, 60, 65, 70°C), relative humidity (20, 30, 40, 50%), and sample thickness (5, 7, 9 mm) on drying characteristics of yam slices were studied. Results indicated that all the three factors had significant influence on the drying kinetics, whereas drying temperature gave the most significant effect, followed by relative humidity and sample thickness. Moisture-effective diffusivity and activation energy were calculated, and it was found that the diffusivity was in the range of 5.5454 × 10−10–1.0804 × 10−9 m2/s and the activation energy was 29.528 kJ/mol. Heat and mass transfer models were developed based on the finite element method to calculate the core temperature and moisture distribution of yam slices during drying. Model validation exhibited good agreement...

Color changes, nitrite content, and rehydration capacity of edible bird's nest by advanced drying method

Abstract: This article presents the authors’ first attempt to improve quality of edible bird’s nest through continuous and intermittent low-temperature drying (25 and 40°C) with infrared and ultraviolet C (UVC) treatments. The attributes of quality were compared in regard to quality of hot-air-dried samples at 70–90°C. Experimental results showed that a significant improvement in the quality of edible bird’s nest in terms of minimizing color changes and rehydration capacity using intermittent low-temperature drying with infrared and UVC drying profile. However, it was also found that any drying method has less significant effect on the nitrite content of edible bird’s nest.

Freeze Drying: Effects on Sensory and Nutritional Properties

Abstract: Most food products require drying to remove excess water in order to prolong its shelf life by preventing microbial deterioration. Often, product quality degrades during the process due to thermal degradation and denaturation. Therefore, low-temperature drying such as freeze-drying is preferred for the drying of these food materials to produce high-quality dried foods. It is well known that freeze-drying can preserve color as pigments are susceptible to thermal reaction; produces more porous and better textured dehydrated products as sublimation of ice leaves pores within the solid matrix, thus making the matrix softer and giving a high rehydration ratio; and gives excellent retention of aroma compounds and bioactive ingredients due to low-temperature processing.

Transparency phenomena of flat-rice noodles (kuew teow) at drying at soaking variation

Abstract: This paper presents a transparency phenomenon that occurred in hot air and heat pump dried flat-rice noodles, which is explained by the higher colour changes, glassy puffing microstructures, and lower fat content in comparison to the freeze dried flat-rice noodles. Hot air drying and heat pump drying recorded the colour changes at an average of 43.87 ± 1.5 twice than colour change caused by freeze drying at 19.33 ± 1.12 to verify the transparency caused by employing high temperature to eventually increase the sample lightness. However, the microstructures study suggested that freeze drying produced distinct pores ranging from 2.05 μm to 27.68 μm whereby hot air drying and heat pump drying merely produced glossy transparent texture. Indeed, the pores disclose the fat content recorded by freeze drying in flat-rice noodles at 5.62% ± 0.2 twice than the fat content recorded by hot air and heat pump drying at 2.48% ± 0.49. Therefore, by learning the transparency phenomenon in hot air and heat pump dried noodles approves that freeze drying eventually preserves the quality attributes of flat-rice noodles as closest to the fresh flat-rice noodles in terms of colour, microstructures, and fat content.