Changes in physicochemical properties of moisture, ash, and fat contents, and color, due to freeze and oven post-drying treatments on flavedo, albedo, and lamella pomelo fruit peels were investigated. Physicochemical properties influence consumer acceptability and only a few studies are known. Pomelo peels were subjected to freeze drying and conventional drying at 60°C. Fresh pomelo peel was used as a control. Post-drying treatment changes in moisture, ash, and fat contents were observed, compared to controls. Minimal color changes were observed for freeze drying, compared with oven drying for flavedo, albedo, and lamella. Useful information for evaluation of drying treatments that can be used on pomelo peels is provided.
Lipase-catalyzed production of palm esters was performed via alcoholysis of palm oil and oleyl alcohol in solvent and solvent-free systems using a 2 L stirred tank reactor (STR). Two immobilized lipases were tested and Lipozyme RM IM exhibited superior performance in both reaction systems. Reusability studies of the enzymes in a solvent-free system also demonstrated the high stability of Lipozyme RM IM as shown by its ability to yield more than 70% palm esters with up to 19 cycles of reusing the same enzymes. Modification of the enzyme washing process improved the stability of Lipozyme TL IM in a solvent system as demonstrated by maintaining 65% yield after 5 times of repeated enzyme use. The scale up process for both lipases was conducted in the presence of solvents by using the impeller tip speed approach. Lipozyme RM IM-catalyzed reaction in a 15 L STR produced 85.7% yield and there was a significant drop to 60.7% in the 300 L STR, whereas Lipozyme TL IM had a lower yield (65%) when the reaction volume was increased to 15 L. The low yields could be due to the accumulation of enzymes at the bottom of the vessel. Purification of palm esters via solvent-solvent extraction revealed that more than 90% of oleyl alcohol was extracted after the third extraction cycle at 150 rpm impeller speed with reduced palm esters: ethanol ratio (v/v) from 1:4 to 1:3.
Edible bird's nest (EBN) is made up of sialylated-mucin glycoprotein with various health benefits due to its high antioxidative activity. However, as a macromolecule with distinct charged sialic acid and amino acids, fractions with different charges would have varied physicochemical properties and antioxidant activity, which have not been studied. Therefore, this study aimed to fractionate and purify the enzymatic hydrolysed of cleaned EBN (EBNhc) and EBN by-product (EBNhbyp) through anion exchange chromatography (AEC), and determine their molecular weights, physicochemical properties, and antioxidative activities. Overall, 26 fractionates were collected from enzymatic hydrolysate by AEC, which were classified into 5 fractions. It was found that the positively charged fraction of EBNhc (CF 1) and EBNhbyp (DF 1) showed the significantly highest (p