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Pomelo (Citrus grandis (L.) Osbeck) is an important cultivar of the Citrus genus, which contains a number of nutrients advantageous to human health. Non-edible parts of pomelo consist of flavedo, albedo, lamella and waste obtained from juice extraction (pulp waste). The peels are also thought to be part of waste products, which generally being discarded. Therefore, the objective of the present study was to evaluate changes in total phenolic contents (TPC) and antioxidant activity of processed pomelo peels after oven drying (50 and 60 °C) and freeze drying treatments in comparison with fresh pomelo peels. A slightly different (4%-6%) in TPC was observed in oven dried pomelo peels in comparison with fresh peels, indicating that there was a slightly effect of post-drying methods on retaining the antioxidant potential of these natural byproducts. In vitro assays revealed that post-drying methods involved oven drying exerted a higher TPC compared to freeze drying in overall parts of pomelo byproducts. Highest retention of bioactive compounds was found in fresh pomelo peels (437-1876 mg GAE/100 g DM), followed by oven dried at 50 and 60 °C (892-1336 mg GAE/100 g DM), and freeze dried (555-1267 mg GAE/100 g DM). In terms of oven dried pomelo byproducts, the highest TPC was retained in albedo (1337 mg GAE/100 g DW), followed by flavedo (1226 mg GAE/100 g DW), lamella (998 mg GAE/100 g DW) and pulp waste (962 mg GAE/100 g DW) respectively. Therefore, oven drying was the most suitable post-drying method to retain the bioactive compounds for pomelo byproducts. This knowledge may inspire consumer or pomelo industry operators to re-evaluate their byproducts, reduce the waste and expand the application of pomelo fruits.

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Background: Coconut sugar has a caramel color with a taste like brown sugar. It is commonly used as natural sweetener. However, coconut sugar has been produced from coconut sap using a traditional method that involves heating the sap at high temperature (>100 °C) in an open pan for a long period (3-5 h). This conventional method results in an over-cooked sugar, which leads to quality deterioration in terms of both its physical and chemical properties. The current study aimed to investigate the processing of coconut sap into sugar syrup using alternative processing techniques such as rotary vacuum evaporation (RE) and microwave evaporation (ME), comparing them with open-heat evaporation (OHE) technique. Results: Coconut sugar syrup produced by rotary evaporation at 60 °C and 250 mbar vacuum (RE-60) required the shortest production time (12.2 min) and the lowest processing temperature (54.8 °C) when compared with ME (13 min and 103.2 °C) and OHE (46.8 min and 101.6 °C). It also had a light brownish color with a higher L* value (35.17) than the ME (29.84) and OHE (23.84) methods.It was found to contain higher amounts of monosaccharides (fructose and glucose) and lower amounts of disaccharides (sucrose). Furthermore, the amount of energy required for RE-60 (0.35 kWh) was much less than for OHE (0.83 kWh). Conclusion: This study provided an alternative processing method for the sugar processing industry to produce coconut sugar using the rotary evaporation method at 60 °C under 250 mbar vacuum with better physicochemical qualities, shorter processing time, and minimum input energy.

Rice is a staple food in the world market, especially in the Asian region. In each country, the characteristics of rice will be different in terms of shape, grade and size. The quality of rice depends largely that demonstrate the quality of that rice species. At present, information on rice varieties is still limited regarding the physical properties of Malaysian and Thai rice. Therefore, it is important to compare rice cultivars based on origin. The objective of this research is to determine and compare the physical properties of Malaysian and Thai rice. 1 kilogram of Malaysian and Thai rice were each processed into powder by way of grinding and were then prepared for physicochemical measurement by sieving the produced rice powders with a size of 2mm to get rid of foreign objects. The physical parameters measured were length, width, length/breadth ratio, thickness, density, grain shape, surface area, bulk density, true density, porosity, sphericity, aspect ratio, thousand weight kernels angle of repose, colour (L, a*, b*) and hardness. The results of the study showed no significant differences (p>0.05) in terms of length, width, length/breadth ratio, true density, porosity, sphericity, aspect ratio, angle of repose, Lightness (L) and b*. However, there is a significant variation (p < 0.05) between Malaysian and Thai rice in terms of thickness, surface area, bulk density, thousand weight kernels, colour (a*) and hardness parameters. The evaluation of the quality of Malaysian and Thai rices can be a guide or reference for the grading and sorting processing sectors.

The objective of this research was to develop a microwave‐vapor heat treatment (MW‐VHT) for mangoes (Mangifera indica L.) cv. Namdokmai Si Thong to disinfest the oriental fruit fly, Bactrocera dorsalis (Hendel). The mortality of oriental fruit fly eggs and quality acceptability characterized by thermal‐death‐time and thermal‐quality‐time overlay plots were initially obtained by hot‐water immersion. Two treatments within a range of acceptable quality were selected for inoculation experiments to confirm MW‐VHT process. The acceptable range was temperature ranging from 46 to 55C with time ranging from 2 to 20 min. The MW‐VHT using microwave for preheating followed by vapor for holding processes effectively disinfested oriental fruit fly eggs. Changes in physiochemical properties of mangoes, e.g., color, titratable acid (TA), total soluble solid (TSS), TSS/TA and firmness, of MW‐VHT‐treated mangoes were not significantly different (P > 0.05) from physiochemical properties of the nontreated mangoes. MW‐VHT resulted in less heat damage of mangoes than conventional vapor heat treatment (VHT) and shortened process time more than 90% during the preheating period. MW‐VHT also retained equivalent or better lethality of oriental fruit fly eggs than did conventional VHT.

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