MICROENCAPSULATION OF LOBSTER CAROTENOIDS WITHIN POLY(VINYL ALCOHOL) AND POLY(D,L-LACTIC ACID) MEMBRANES

The use of natural pigments such as lobster carotenoids in fish feed f ormulations offers advantages over the use of the synthetic alternativ es. Microencapsulation of the pigments, with or without the addition o f antioxidants to the formulation, may be of benefit in terms of stabi lizing pigment colour. In the present study, lobster carotenoids were extracted from lobster shell into petroleum ether and microencapsulate d by phase separation and salt coacervation within poly(vinyl alcohol) and poly(vinyl alocohol)/poly(D,L-lactic acid) membranes. Spherical m icrocapsules, with smooth, thin and resilient membranes were obtained with mean diameters ranging from 50 to 150 mu m, depending on the memb rane material, and source of pigment. The microcapsules were pink-oran ge in colour, and colour stability was followed spectrophotometrically . Enhanced stability was observed in both membrane materials, in compa rison to the non-encapsulated control. Rates of discoloration were det ermined under a variety of storage conditions, including the absence o f light, reduced temperatures and under nitrogen atmosphere. The best stability of lobster carotenoids was observed under a nitrogen atmosph ere within PVA/PLA membranes, representing an 11-fold enhancement of p igment stability in comparison to the controls. Under ambient conditio ns, the enhancement in pigment stability was approximately 6-fold. The optimum concentration of PVA during microencapsulation was 3-4%, and the microencapsulated pigments appeared most stable under acidic condi tions. The rate of discoloration appeared independent of pigment conce ntration.