Purification of juices extracted from Stevia rebaudiana leaves by salt precipitation

Abstract

Stevia rebaudiana is a perennial herbaceous plant, part of the Asteraceae family and native of Paraguay [1]. It has been cultivated in China and Southeast Asia for several decades [2] and more recently in France, in the Occitanie region. More commonly known as “Stevia”, it is a new source of natural sweetener, since it contains steviol glycosides with a sweet taste. The objective of the work carried out is to develop a method of purification of juice extracted from Stevia rebaudiana leaves, pre-purified by various membrane filtration operations, supplied by the company OVIATIS. The objective is to increase the purity of steviol glycosides in these juices, by precipitating impurities such as quinic acid. These juices initially have a purity of 23 ± 2.5 g of glycosides/100 g of dry matter (ie 23%). The tests presented in this study make it possible to assess the impact of the addition of ethanol, whether or not combined with the addition of potassium or calcium hydroxide. The addition of ethanol to the juices leads to an increase in purity and makes it possible to reach a value of 32 ± 3%. By combining the addition of ethanol with the addition of calcium hydroxide, a purity greater than 50% is obtained. Indeed, for a calcium hydroxide ratio of 0.06, the purity reached a level of 56 ± 5% during the test.