The high share of steryl esters is responsible for the unusual sterol pattern of black goji berries

Abstract

Phytosterols are bioactive and healthy components of the human diet. Although numerous investigations reported the rich nutrients in black goji berries, comprehensive data on the sterol pattern were missing. In this study, gas chromatography with mass spectrometry (GC/MS) analysis enabled the detection of 23 sterols and 22 fatty acids in dried black goji berry samples. Black goji berries were dominated by ∆5-avenasterol (mean: 23.7 %) > the rare campesta-5,24(25)-dienol (mean: 19.2 %) > β-sitosterol (mean: 14.9 %). Investigations of the reasons for this unique sterol pattern showed that ∼76% of the sterols in black goji berries were esterified with fatty acids (steryl esters). This share of steryl esters was higher than in virtually all other plant samples where free sterols are predominant. Remarkably, the rare campesta-5,24(25)-dienol was most prominent in the steryl ester fraction. Manual separation and analyses of seeds and pulp subsamples showed that most of the sterols were found in seeds where steryl esters were predominant (∼71 %), while the pulp was dominated by free sterols (∼73 %). Hence, the unconventional sterol pattern of black goji berries mainly originated from the high share of steryl esters in the seeds in combination with different sterol patterns in free and esterified sterols.