ABSTRACT
Objective To evaluate the variation of sweet chemicals (sugars and betaine) in fruits of six species in genus Lycium L. i.e. Lycium truncatum, L. cylindricum, L. dasystemum, L. dasystemum var. rubricaulium, L. chinense, and L. barbarum harvested at three different ripening stages. Methods A simple and effective method based on UPLC-ELSD was developed for the simultaneous determination of two monosaccharides (glucose and fructose), two disaccharides (sucrose and maltose), one sugar alcohol (xylitol), and betaine in wolfberry fruits (goji berries) of genus Lycium L. Results The six species of wolfberry fruits harvested at the three different ripening stages were evaluated in sugars and betaine contents. Fructose and glucose were the predominant sugars in mature wolfberry fruits. Fructose, glucose, and betaine, as well as total sugar contents, increased continually over the ripening process. L. truncatum and L. dasystemum had higher contents of sugars and betaine than the other species. Conclusion UPLC-ELSD is a simple, reliable and effective method for analysis of the sweet chemicals in wolfberries. Wolfberry fruits at the different ripening stages were significant different in sweetness. L. truncatum and L. dasystemum could be the potential sources of wolfberry fruit sources.