No abstract

Techno-biofunctional characteristics of nanoemulsion and (nano)emulgel loaded with mangostin extracts were elucidated. Crude mangostins from mangosteen peels recovered by virgin coconut oil (VCO), mixed VCO and propylene glycol (PG), and pure PG were used. The extracts were loaded in the dispersed phase in the presence of mixed surfactants (Tween20/Span20) with a varying hydrophilic-lipophilic balance (HLB) from 10.2 to 15.1. Results showed that globular and uniformly distributed droplets of the nanoemulsion were observed. The small particle sizes (typically 18-62 nm) with the zeta potential of-39 to-54.5 mV were obtained when mixed emulsifiers with HLB values of 12.6 and 15.1 were employed. With HLB values of 12.6 and 15.1, nanoemulsions loaded with mangostin extracts prepared with mixed VCO-PG and pure PG-based extracts showed approximately a 2 to 3-fold lower droplet size diameter when compared with the VCO-based extract. For the stability test, all nanoemulsions were stable over three freeze-thaw cycles with some changes in pH, zeta potential, and droplet size. The DPPH • scavenging activity, H 2 O 2 scavenging activity, reducing power and antibacterial activities (E. coli and S. aureus) of the nanoemulsions were greater than their corresponding bulk extracts. Nanoemulgels produced by embedding the nanoemulsions in a hydrogel matrix was homogeneous and creamy yellow-white in appearance. The nanoemulgels had a higher mangostin release (87-92%) than their normal emulgels (74-78%). Therefore, this study presented the feasibility of nanoemulsions and nanoemulgels loaded with mangostin extracts as a promising delivery system for bioactive polyphenol in food supplements, pharmaceuticals and cosmetics.

Virgin coconut oil (VCO) and propylene glycol (PG) have received more attention as bio-based solvents for natural bioactive recovery in green extraction process.Here, maceration extraction and ultrasound-assisted extraction (UAE) of bioactive phenolics from mangosteen peel (MP) by VCO, PG and VCO-PG mixture were compared. The goal was to maximize the phenolic extraction and improve bioactivities. Based on a single-factor experiment for UAE with VCO, the optimal condition was sample to solvent ratio of 1:6.6 g/mL, amplitude of 55 lm, and extraction time of 7 min, which yielded total phenolic content of 365 mg GAE/100 g. Regarding the extraction methods and bio-based solvents, UAE with mixed VCO-PG was not only provided greater polyphenol yield in a shorter time, but it also enhanced the bioactivities (radical scavenging, antibacterial, and antidiabetic activities) of the extract. Therefore, UAE can be potentially used in combination with bio-based solvents, especially mixed VCO-PG, for maximizing bioactive phenolic isolation from MP. This study provided an alternative method for production of bio-based oil solution from MP which can be directly used as a functional ingredient in emulsion based food, neutraceutical and cosmetic products.

Commercial lipases were tested for the ability to hydrolyze palm olein in isooctane in a two-phase system. Lipase OF (from Candida rugosa) showed the highest specific activity of 209 U/mg protein where 1 U is the amount of lipase enzyme required to produce 1 µmol of fatty acid (as palmitic acid) per minute. The enzyme was adsorbed completely on Accurel EP100 (particle size <200 µm) with 20.5% activity retained. The soluble and the immobilized lipase OF showed optimal activity at the same pH and temperature (pH 6.5-7.5 and 35°C). However, the immobilized lipase had a wider range of pH and higher temperature stability. Continuous hydrolysis of palm olein was performed in a packed-bed reactor with 656 U of immobilized enzyme. The substrate (20% palm olein in isooctane) and Tris/maleate buffer were fed concurrently at the flow rates of 0.08 and 0.04 mL/min, respectively. The system gave a degree of hydrolysis (DH) of 90-100% for up to 250 h. A more stable system allowing for more than 300 h operation at DH > 95% was achieved by mixing the immobilized enzyme with 1000-1500 µm Accurel EP100 to increase the system porosity and continuous feeding of the aqueous phase recycling from the product mixture. A similar result was also obtained using 1007 U of the immobilized enzyme and 60% palm olein in isooctane fed at 0.06 mL/min.