Improvement of torularhodin production by Rhodotorula glutinis through the stimulation of physicochemical stress and application of the bioproduct as an additive in the food industry

Carotenoids are pigments responsible for the red–orange colorations in valuable food products, and they can be produced via biotechnological means through microorganisms. Beyond their role as natural colorants, some carotenoids offer significant health benefits due to their antioxidant properties, making them valuable nutritional additives in the food industry. However, obtaining these compounds from natural sources with high quantity and purity poses challenges which reduces its market share when produced through a biotechnological route. This study proposes utilizing nutritional and physical stress to enhance carotenoid production, specifically torularhodin, using the yeast Rhodotorula glutinis CCT-2186. A Design of Experiments approach identified malt extract as the most suitable nitrogen source for maximizing carotenoid production. Furthermore, introducing a surfactant (Tween 80) in the culture medium, and extending the cultivation time to 96 h, led to an increase in torularhodin production, reaching a notable 2.097 mg/mL (377,68% more when compared to the initial condition) under the best condition [(%w/v): dextrose (1), KH2PO4 (0.052), MgSO4.7H2O (0.052) and NH4NO3 (0.4), malt extract with a pH of 5.0/ 96 h/30 °C]. Lastly, to demonstrate the viability of utilizing the carotenoid extract as a food colorant, it was applied in edible gelatin. These findings highlight the critical role of nutritional, physical, and mechanical stresses in optimizing torularhodin production, particularly the conversion of γ-carotene to torularhodin by R. glutinis.