The influence of diacylglycerol (DAG) combined with polyglycerol polyricinoleate (PGPR) on the stability of water-in-oil (W/O) emulsions containing hydrogenated palm oil (HPO) was studied. Polarized light microscope revealed that DAG promoted HPO to crystallize at the water-oil interface, providing the combination of Pickering and network stabilization effects. It was proposed that the molecular compatibility of fatty acids in DAG with HPO accounted for the promotional effect. The interfacial crystallization of DAG together with the surface activity of PGPR led to the formation of emulsions with uniform small droplets and high freeze-thaw stability. Further exploration of physical properties indicated that the combination of DAG and PGPR dramatically improved the emulsion's viscoelasticity and obtained a larger deformation yield. Water droplets in DAG-based emulsions acted as active fillers to improve the network rigidity. Therefore, DAG is a promising material to be used as emulsifier to enhance the physical stability of W/O emulsions.
A series of ester compounds derived from ricinoleic acid to be used as biolubricants base stock have been synthesized. The resulting products were confirmed by FTIR and NMR analyses. The synthesis was carried out in three stages: epoxidation of ricinoleic acid; synthesis of 10,12-dihydroxy-9-acyloxystearic acid from epoxidized ricinoleic acid with various fatty acids and esterification of the acyloxystearic acid products with octanol to yield octyl-10,12-dihydroxy-9-acyloxystearate. The viscosities, flash points and pour points (PP) behavior of the products were measured. The resulting esters had an increased in molar weight and viscosity and decreased in pour points as compared to ricinoleic acid.
The crude oil of Malaysian castor bean Ricinus communis L. seed was extracted by Soxhlet method using hexane. The physicochemical characteristics of castor bean oil were evaluated. The results showed that Malaysian castor seeds contain a relatively high percentage of total lipids content; 43.3% (per dry weight), high iodine value (84.5 mg/g) and saponification value (182.96 mg/g). The seed oil moisture content, acid value and free fatty acid percentage (% FFA) were 0.2%, 4.88 mg/g and 3.4%, respectively. The unsaturated fatty acids (UFA) content were 97.5% of the total fatty acids composition. Ricinoleic acid comprises over 84% while other fatty acids present were linoleic (7.3%), oleic (5.5%), palmitic (1.3%), stearic (1.2%) and linolenic (0.5%), respectively. Five types of castor bean seed oil triacylglycerols were identified as triricinolein, RRR (84.1%), diricinoleoylstearoylglycerol, RRS (8.2%), diricinoleoyloleoyl-glycerol, RRO (5.6%), diricinoleoyllinoleoylglycerol, RRL (1.2%) and diricinoleoylpalmitoyl-glycerol, RRP (0.9%) respectively.
The aim of this work was the synthesis of a novel hydroxyl-fatty acid derivative of kojic acid rich in kojic acid monoricinoleate (KMR) which can be widely used in the cosmetic and food industry. The synthesis of KMR was carried out by lipase-catalysed esterification of ricinoleic and kojic acids in solvent-free system. Three immobilized lipases were tested and the best KMR yields were attained with Lipozyme TL IM and Novozym 435. Since Lipozyme TL IM is the cheapest, it was selected to optimize the reaction conditions. The optimal reaction conditions were 80 °C for the temperature, 1:1 for the alcohol/acid molar ratio, 600 rpm for stirring speed and 7.8% for the catalyst concentration. Under these conditions, the reaction was scaled up in a 5×10⁻³ m³ stirred tank reactor. ¹H-¹³C HMBC-NMR showed that the primary hydroxyl group of kojic acid was regioselectively esterified. The KMR has more lipophilicity than kojic acid and showed antioxidant activity that improves the oxidation stability of biodiesel.