Simultaneous enrichment of cereals with polyunsaturated fatty acids and pigments by fungal solid state fermentations

•Biotechnological enrichment of cereals with bioactive compounds.•Fungal solid state fermentations.•Effect of cultivation condition on production of gamma-linolenic acid and β-carotene.

Four Mucor strains were tested for their ability to grow on four cereal substrates and enriched them with gamma-linolenic acid (GLA) and β-carotene. M. circinelloides CCF-2617 as the best producer accumulated of both GLA and β-carotene in high amounts during utilization of rye bran/spent malt grains (3:1). The first growth phase was characterized by rapid GLA biosynthesis, while distinct β-carotene formation was found in the stationary fungal growth. Therefore various cultivation conditions were tested in order to optimize the yield of either GLA or β-carotene. The fungus grown on cereal substrate supplemented with glucose produced maximal 8.5 mg β-carotene and 12.1 g GLA in 1 kg fermented substrate, respectively. On the other hand, the highest amount of GLA in the fermented substrate (24.2 g/kg) was achieved when 30% of sunflower oil was employed to the substrate. Interestingly, β-carotene biosynthesis was completely inhibited when either whey or linseed oil were added to the substrate.