Optimisation of the enzyme-assisted extraction of polyphenols from saffron (Crocus sativus L.) petals

Abstract

Background. Saffron tepals are a by-product from the processing of Crocus sativus flowers, whose dried stigmas (saffron spice) are widely used both in the food and health sectors. Saffron tepals are rich in polyphenols, particularly flavonol glycosides and anthocyanins, which are considered to be potent antioxidants. Enzyme-assisted extraction of polyphenols offers several advantages in comparison to conventional methods. The present study evaluated the efficiency of enzyme-assisted extraction as a green technology for recovery of polyphenols from saffron tepals. Materials and methods. The by-product was obtained from a saffron producer in the region of Kozani, Greece. A simplex-centroid design was applied to select the enzyme preparations mixture required for aqueous extraction of polyphenolic antioxidants from dried saffron tepals. In addition, the parameters of enzymatic hydrolysis, enzyme dose and incubation time were optimised using response surface methodology. Results. The binary combination, comprising cellulolytic and hemicellulolytic preparations (1:1), led to the highest yield of total polyphenols (30.9 g GAE/kg saffron tepals) and total anthocyanins (2.0 g CGE/kg saffron tepals), reaching 45% and 38% higher values, respectively, as compared to the control sample (without enzymatic treatment). The experimental data regarding optimisation of the extraction conditions were fitted to second-degree regression models (R 2 = 0.85-0.98).