Effect of enzymatic pretreatment on the extraction yield of Stevia rebaudiana leaves
2018
Formigoni, M. | Milani, P. G. | Dacome, A. S. | Costa, S. C.
Stevia rebaudiana (Bert.) is a plant, which has in its constitution, especially in the leaves,steviol glycosides with sweetener power. This plant is worldwide studied with the main aim of effectively extract these compounds. The aim of this study was to evaluate the effect of an enzymatic pretreatment on the S. rebaudiana leaves by using cellulase enzyme on the yield of an extraction using conventional methods. The pretreatment was made in different durations (15, 30, 45, 60 min) with a relation of 1:5 (w/v), at 50°C and 150 rpm, followed by an aqueous extraction at 1:10 (w/v), 50°C and 120 rpm. It was verified that the pretreatment duration directly influences the yield of glycosides extraction, with 1 hour being defined as the best duration. The enzymatic pretreatment before the extraction demonstrated to be very effective for the global extraction yield, since there was a raise of 34.4% in the total yield when compared with the same extraction without pretreatment. A high extraction yield (71%) of glycosides originally present in the leaves was also observed in treated leaves extract when compared with untreated leaves extract (56%) in just one cycle. Among them, the one which exhibited higher content was rebaudioside A, which has superior sensory characteristics. It is concluded then that the enzymatic pretreatment before sweeteners extraction of S. rebaudiana leaves is a viable alternative, with similar recovery to modern techniques. However, it is presented as a simple, fast, inexpensive and advantageous methodology in relation with other techniques which are expensive and may present application difficulties in industrial scale.
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