Chaleeda Borompichaichartkul

Microencapsulation of Kaffir Lime Oil and Its Functional Properties

This paper describes the effects of spray drying temperature and wall materials on functional properties of kaffir lime oil microcapsules. The effects of spray drying were studied at inlet air temperatures at 160, 180, and 200°C. Two coating materials (konjac glucomannan and gum arabic) were employed in this study. The results indicate that kaffir lime oil had antibacterial activity against all tested pathogens and was able to inhibit Vibrio cholerae comparable to a standard antibiotic. The combination of konjac glucomannan and gum arabic (KGM+GA) can enhance the yield and retention of total oil in the microcapsules more than using konjac glucomannan alone as a wall material. Increasing inlet air temperature resulted in a decrease of antibacterial activity and amount of bioactive volatile compounds. Physical and chemical properties of the microcapsules did not differ significantly (p > 0.05) in terms of process yield, a w , moisture content, efficiency in retention of total, surface and inner oil, water solubility index, and color except at inlet air temperature of 200°C. However, it was found that the kaffir lime oil microcapsules from KGM+GA produced at inlet temperature of 180°C had the best functional properties in terms of antibacterial activity and efficiency of retention of total encapsulated oil.

Changes of Chemical and Physical Quality Attributes of Macadamia Nuts during Hybrid Drying and Processing

Macadamia nuts are well known for their unique flavor and taste. They contain a high level of monounsaturated fatty acids such as oleic acid, which is claimed to have an effect on reducing blood cholesterol. This study focuses on monitoring the changes in the physical and chemical qualities of macadamia nuts during drying, roasting, and storage. A combination of heat pump drying and tunnel drying was selected for this study to provide a comparison with convectional hot air drying. After completion of all drying treatments, the dried nuts were subjected to roasting at 125°C for 20 min and storage in ethylene vinyl alcohol copolymer (EVOH) bags at 4°C for 3 months. After each stage of processing, nut samples were taken to assess the quality in terms of fatty acids, moisture content, water activity, peroxide value, free fatty acids, color, and volatile compounds. The experimental results showed that drying treatments using heat pump combined with tunnel drying can reduce drying time significantly. It appears that the combination of heat pump and tunnel drying resulted in maintaining the commercially accepted chemical and physical quality characteristics of macadamia nuts in terms of key fatty acid contents, peroxide value, free fatty acid content, and color. Moreover, drying with a heat pump dryer combined with tunnel drying did not increase the content of undesirable volatile compounds in dried macadamia nuts after processing.

Comparative Study of Effects of Drying Methods and Storage Conditions on Aroma and Quality Attributes of Thai Jasmine Rice

This article describes the effects of various drying treatments and storage conditions on the main quality attributes of Thai jasmine rice; i.e., aroma, milling, pasting, and cooking properties. The experimental results show that drying treatments using various high temperatures (115–150°C) combined with 30 min tempering time between the pass or ambient air drying affect the composition of volatile compounds as well as the commercially accepted quality characteristics of Thai fragrant rice. High-temperature drying followed by ambient air drying can retain most of the quality attributes of Thai jasmine rice than multi-pass high-temperature drying with a tempering period between passes.

A New Drying Approach to Enhance Quality of Konjac Glucomannan Extracted from Amorphophallus muelleri

A new drying approach to enhance physical quality of konjac glucomannan extracted from Amorphophallus muelleri was studied. It consisted of a comparison between microwave vacuum drying and conventional hot-air drying. The effects of microwave vacuum drying and hot-air drying on drying kinetics and physical and structural properties such as color, bulk density, particle density, porosity, viscosity, and morphology of konjac glucomannan (KGM) flour were investigated. It can be concluded that microwave vacuum drying significantly reduced drying time and increased porosity of dehydrated products which have a positive effect on the viscosity of the KGM solution. In contrast, it decreased bulk density and particle density when compared with conventional hot-air drying. Microstructure observations revealed the presence of large cavities in the granules of microwave-vacuum-dried KGM samples. However, there was a slight change in color of the microwave-vacuum-dried samples, resulting in a lower whiteness index than the whiteness index of hot-air-dried samples. Hence, microwave vacuum drying was found to have a number of advantages over the conventional hot-air drying method. Therefore, microwave vacuum drying has potential to become a useful drying method for the industrial production of KGM flour.

Konjac glucomannan hydrolysate: A potential natural coating material for bioactive compounds in spray drying encapsulation

This research aimed to develop a suitable coating material for encapsulating a plant bioactive compound via spray drying. A suitable process for modifying the rheological property of konjac glucomannan (KGM) solution by enzymatic treatment was developed. A plant bioactive compound, andrographolide, was selected to use as core material. Mannanase (1500 units of enzyme) was used in the treatment of KGM solution. The concentration of KGM solution was varied from 9 to 18% (w/w). It was found that 12% (w/w) was the optimum KGM concentration that could be hydrolyzed to a viscosity of <100 mPa·s. HPLC analysis of hydrolyzed solution found a fair amount of DP4–DP7 oligosaccharides (where DP is degree of polymerization) were obtained. The solution was then used as coating material in spray drying with inlet air temperature of 170°C and outlet air temperature of 85°C. It was found that 12% (w/w) konjac glucomannan hydrolysate (KGMH) was suitable for coating 2% (w/w) andrographolide. Its efficiency of encapsulation was also higher than that of KGMH combined with gamma‐cyclodextrin or beta‐cyclodextrin. This study revealed a great potential of using KGMH solution for pharmaceutical and food industries in the spray drying encapsulation process.

A soft computing tool for species classification and prediction of glucomannan content in Amorphophallus genus

The proposed work aims at designing a classification system for automatic identification of A. muelleri species, grown as a potential cash crop in many Asian countries, from the DNA fingerprints of Amorphophallus genus. Four sets of 48 DNA fingerprints belonging to 37 species of the Amorphophallus genus, developed with the help of four different primers are considered for the experiment, with an objective to identify only the fingerprints of the species of interest. A second experimental setup deals with the automatic classification of species containing high amounts of glucomannan from the same set of DNA fingerprints of the Amorphophallus genus. For each set of 48 DNA fingerprints generated with a specific primer, the DNA fingerprints are preprocessed to extract a 42 dimensional feature vector which is used to generate a k‐Nearest Neighbor based classifier based on the Leave One Out Cross Validation protocol. Final classification based on outputs from individual classifiers constructed with respect to the four different primers is performed according to a n‐star consensus strategy. The n‐star consensus predicts species A. muelleri with cent per cent accuracy while it predicts species containing glucomannan with a more modest accuracy of 81.25%.

Entrapment of 5‐aminolevulinic acid under edible composite film of konjac glucomannan and chitosan

5‐Aminolevulinic acid (5‐ALA) is a known plant regulator and growth promoter. It is a very sensitive and highly unstable compound that is easy to deteriorate. Here we propose a novel approach to stabilize 5‐ALA into a film. Films from konjac glucomannan (KGM), KGM treated with alkali solution (KGOH), chitosan (CHI) as well as blends between KGOH and CHI were fabricated for 5‐ALA entrapment. It was found that the efficiency of KGM film, KGOH film and CHI film for 5‐ALA entrapment was 55.7 ± 0.73%, 58.3 ± 0.36% and 60.3 ± 0.18 %, respectively. A 25:75 (%w/w) blended film (KGOH/CHI) showed the highest entrapment efficiency of 5‐ALA (65.9 ± 0.37%) versus other films. The possible mechanism for entrapment of 5‐ALA in blended film was postulated under two mechanisms. A secondary amide that leads to the interaction between the amino group of CHI and carboxyl group of 5‐ALA is proposed as the first mechanism. The fact that the 5‐ALA molecule was entrapped within the complexity of KGOH structure is proposed as the second mechanism. Therefore, stabilizing 5‐ALA in a film may be an alternative way to use and preserve 5‐ALA for further applications.