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Phytosteryl ester synthesized with pinolenic acid (PLA) from pine nut oil is expected to have features of both phytosterol and PLA. In this study, lipase from Candida rugosa (CRL) was immobilized and then used to optimize conditions for synthesis of phytosteryl ester containing PLA. Lewatit VP OC 1600, a macroporous hydrophobic resin, was selected as the best carrier, and the optimum condition for the immobilization of CRL was established. With immobilized CRL prepared, synthesis of phytosteryl ester with fatty acid from pine nut oil was carried out. Parameters investigated were temperature, molar ratio (phytosterol to fatty acid), enzyme loading, and vacuum. Optimum conditions for synthesis of phytosteryl ester were a temperature of 60 °C, molar ratio of 1:4, enzyme loading of 10% (based on the total weight of the substrate), and pressure of 80 kPa. The maximum conversion of phytosteryl ester was ca. 93 mol % at the optimum condition.

Curcumin, a hydrophobic phenolic compound isolated from tumeric (Curcuma longa), has gained a great attention due to its health benefits and antimicrobial effects. In this study, curcumin nanoparticles (CNPs) were formulated via acusto‐plastic deformation technique, with three differently surface‐charged surfactants‐sodium dodecylsulfate, Tween 20 and cetrimonium bromide (CTAB). The fabricated CNPs were evaluated for their antimicrobial activity against Listeria monocytogenes, one of the most severe foodborne pathogens. Our results demonstrated that the CNPs formulated with positively charged surfactant (CTAB) exhibited the highest antimicrobial activity against L. monocytogenes, indicating that there is a strong relationship between surface charge and antimicrobial activity of curcumin. The enhanced antimicrobial action of CNPs‐CTAB was concluded to be due to the increased cell‐antimicrobial interaction, which resulted from the opposing electrical charges between CNPs‐CTAB and L. monocytogenes cells, as well as increased antimicrobial penetration endowed by the small size. Practical applications In this study, we showed that surface charge as well as the small size of curcumin nanoparticles play a key role in enhancing cell‐antimicrobial interaction and antimicrobial efficacy. The fabricated CNP‐CTAB showed the best antimicrobial activity against Listeria monocytogenes. A size reduction to nano‐scale is a recently developed strategy used to improve drug/food delivery and matching the public demand for effective and safe antimicrobial formulations for control of foodborne pathogens.

Stearidonic acid (SDA) from echium oil was enriched substantially by a two-step lipase-catalyzed esterification using Lipase OF from Candida rugosa and Lipozyme RM IM from Rhizomucor miehei. During the first step, SDA was enriched in the fatty acid fraction via C. rugosa lipase-catalyzed esterification with lauryl alcohol. The optimum reaction conditions of water content, temperature, and enzyme loading were 0.25%, 30°C, and 2%, respectively, in terms of the content and yield of SDA. Under these conditions, SDA content was increased to 39.3 from 14.3% of the starting material. To further elevate SDA content, Lipozyme RM IM-catalyzed esterification was then conducted using the SDA enriched fatty acid from the first step and a maximum SDA content of 54.1% was obtained. Using this two-step lipase-catalyzed esterification, SDA content increased fourfold from 14.3 to 54.1% with a 74.8% yield. g-Linolenic acid (GLA) was also enriched together with SDA.Practical applications: SDA, which is one of v-3 fatty acids, is considered as a source of health beneficial polyunsaturated fatty acids for vegetarians. SDA enrichment obtained in this study leads also to a high level of GLA. Therefore, this enrichment can be applied to produce a novel structured lipid containing a significant amount of SDA and GLA.

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