Relative stabilities of microalgal carotenoids in microalgal extracts, biomass and fish feed: effect of storage conditions

Abstract

Carotenoids, whose functional importance has become the object of much attention in the last years, are a source of vitamin A and food colouring agents for both animals and/or humans. As consumer demand for natural carotenoids increases, there is a natural barrier to their utilisation insofar as their low stability to oxidative environments is concerned. The aim of this work was to test stability of carotenoids present in microalgal biomass, such as Chlorella vulgaris (Cv) and Haematococcus pluvialis (Hp), already proven to be efficient colouring agents and of their acetone extracts, both as such and in formulated feeds, under different storage conditions, namely at room temperature under light exposure, at room temperature in the dark, frozen at −18 °C, with added antioxidant (0.01% ascorbic acid at room temperature) and stored under vacuum or nitrogen atmosphere. The best storage conditions for microalgal dry biomass carotenoids were under vacuum in both microalgae, when retention totaled 80 and 90%, respectively, for Cv and Hp, even after 1.5 years. Carotenoid extract stabilities were found to be much shorter, and loss of carotenoid pigments was almost total after 15 and 30 days, respectively, for Cv and Hp. In formulated diets, carotenogenic biomass revealed stability during the maximum storage period of six months. As a conclusion, both microalgal dry biomasses may constitute natural, encapsulated and relatively concentrated forms of edible carotenoids, which exhibit good preservation without any special storage conditions, both as such or in finished fish feed.