The use of proteins [whey protein isolate (WPI) or soy protein isolate (SPI)] in combination with dried glucose syrup (DGS) for stabilization of microencapsulated spray-dried emulsions containing tuna oil, palm stearin, or a tuna oil-palm stearin blend was investigated. Pre-emulsions containing heated (100°C/30 min) protein-DGS mixtures and oils at oil/protein ratios of 0.75:1 to 4.5:1 were homogenized at two passes (35+10 or 18+8 MPa) and spray-dried to produce 20-60% oil powders. Microencapsulation efficiency decreased at lower homogenization pressure and as the oil load in the powder was increased beyond 50% but was independent of the type of oil encapsulated and the total solids (TS) content of the emulsions (24-33% TS) prior to drying. Oxidative stabilities of the powders, as indicated by headspace propanal values and PV after 4 wk of storage at 23°C, generally decreased with increasing oil content and homogenization pressure but increased with increasing TS of the emulsion prior to drying. Powder containing palm stearin was more stable to oxidation than powders containing a 1:1 ratio of palm stearin and tuna oil or only tuna oil. Heated WPI-DGS formulations were superior to corresponding formulations stabilized by heated SPI-DGS, producing spray-dried powders with higher microencapsulation efficiency and superior oxidative stability.Paper no. J11336 in JAOCS 83, 965-972 (November 2006).

Spray dried emulsions are effective for carrying and stabilising combinations of fish oil and tributyrin, fish oil and resveratrol, or fish oil, tributyrin and resveratrol in one formulation. The encapsulation efficiencies were >99% for all three bioactives when a heated mixture of sodium caseinate: glucose: dried glucose syrup matrix (Encapsulant matrix 1) was used. When a heated sodium caseinate: glucose: processed starch matrix (Encapsulant matrix 2) was used, the encapsulation efficiencies were 90-92% for tributyrin and approximately 98% for resveratrol for all formulations but 79-91% for tuna oil where the efficiency was more formulation dependent. There was 84-86% remaining EPA, 85-87% remaining DHA, 85% remaining tributyrin and 94-96% remaining resveratrol after 18 months at 25 °C storage of the spray dried emulsions using Encapsulant matrix 1 across all formulations. In comparison, there was 83-87% remaining EPA and 84-89% remaining DHA, 80-82% remaining tributyrin, and 81-100% remaining resveratrol across all formulations with Encapsulant matrix 2. In vitro studies showed that on sequential exposure to simulated gastric and intestinal fluids, <5% tuna oil was found as triglycerides, but all the tributyrin had been lipolysed. The presence of diglycerides, monoglycerides and free fatty acids in the in vitro digests suggested that lipolysis of tuna oil had occurred. The type of matrix used for encapsulating the bioactives had little effect on the lipolysis of the oils but affected the amount of solvent extractable resveratrol. The ability of delivering mixtures of bioactives within one formulation was demonstrated.

No abstract