Stability of β-carotene in spray dried preparation of Rhodotorula glutinis mutant 32

Abstract

Aims: To obtain β-carotene-rich dry cell preparation from mutant 32 of Rhodotorula glutinis and determination of its pigment stability. Methods and Results: The mutant 32 of R. glutinis was grown in a 14 I stirred tank fermenter. Cell mass was concentrated 10-fold by cross-flow microfiltration and then spray dried. Butylated hydroxy toluene (BHT) and D-tocopherol were used as protecting agents. A two-level, three-variable, factorial optimization was performed to achieve moisture-free, non-viable and β-carotene-rich feed additive. Conclusions: The β-carotene and cell mass in stirred tank fermenter were found to be 54 ± 5 mg 1-1 and 12.8 ± 2 g 1-1, respectively. In the presence of BHT, 97 ± 3% (w/w) β-carotene was recovered for all the inlet temperatures studied. The best β-carotene and yeast powder recoveries were obtained at 160°C, 11.6% (w/v) cell mass concentration and 1 g 1-1 BHT. The pigments inside dried yeast powder were stable in dark and cold condition for at least 10 weeks. The purified β-carotene got almost totally denatured, under similar conditions of storage, within 76 h. Significance and Impact of the Study: Spray dried and stable preparation of β-carotene-rich yeast, R. glutinis can provide alternative source of β-carotene for use in animal nutrition.