Enhancement of lutein content in Calendula officinalis Linn. By solid-state fermentation with lactobacillus species

Calendula officinalis Linn contains the highest quantity of lutein in the orange variety of Calendula flowers. It has several benefits like; it protects the eyes from free radicals associated with UV rays on the eye retina. In the present work, we checked the enhancement of lutein content in C. officinalis flowers by solid-state fermentation examined by using four different species of Lactobacillus (L. rhamnosus, L. casei spp. casei, and L. plantrum). These microorganisms were isolated and allowed to ferment over the fresh (FC) and dried (DC) petals of C. officinalis for 10 days in the incubator. The fermented and non-fermented petals were extracted by the hexane extraction method and the presence of lutein was confirmed by HPLC technique, using a reversed-phase C18 column and gradient elution with a mobile phase composed of acetonitrile and methanol (40:60), flow rate of 1.0 ml/min and the UV detection at 446 nm. The highest amount of lutein (9.92 mg/g) was found in dried orange variety Calendula petals fermented by Lactobacillus rhamnosus. However, the orange variety of FC petals showed the highest concentration (40.66 mg/g) in Lactobacillus plantarum. Experiment results concluded that 1 kg of FC petals contains 4.0% of lutein fermented by Lactobacillus plantarum and 1 kg of DC petals contains 0.99% of lutein fermented by Lactobacillus rhamnosus compared with non-fermented and commercial lutein. The non-fermented FC and DC orange flowers contain 1.1% and 0.4% of lutein and commercial lutein contains 0.2%. The process mentioned above was also carried out using ethanol as the solvent for extraction, which showed satisfactory yield, 1 kg of fresh flowers of Calendula contains 0.43% of lutein fermented by Lactobacillus plantarum and 1 kg of DC contain 0.52% of lutein fermented by Lactobacillus rhamnosus.