Evaluation of extraction methods for determination of phenolic compounds, organic acids and sugars in lingonberries (Vaccinium vitis-idaea)

Abstract

Health benefits of lingonberries (Vaccinium vitis-idaea) have been linked to phenolic compounds, whereas organic acids and sugars are important for the taste of the berries. Contents of these compounds combined can be used to determine lingonberry quality. Extraction is a critical step in analyses, and many different methods have been used. The aim of the study was to evaluate different extraction methods and to determine if one single extraction method could be used to measure the content of phenolic compounds, organic acids, and sugars in lingonberries. Depending on extraction method and season, the concentrations of anthocyanins, flavonols, selected flavan-3-ols, and cinnamic acid containing compounds (CAC) in the lingonberries were 48-105, 14-32, 73-189, and 12-23 mg 100 g-1 fw, respectively. The organic acids (2.3-2.9 mg 100 g-1 fw) were mainly citric and quinic acid and the sugars (5.3-6.9 g 100 g) were glucose and fructose. 70% methanol was the best extraction solvent for anthocyanins, whereas 70% acetone was more efficient for flavan-3-ols. For extraction of CAC, flavonols, organic acids and sugars, 70% methanol and 70% acetone were equally efficient. Similar results were obtained from fresh and freeze-dried berries, but deviation between parallels was lower when extracting from freeze-dried berries. Considering both accuracy and time of preparation, extracting freeze-dried berries with 70% methanol was considered the best extraction method for analyzing compounds important for quality of lingonberries.