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Effect of extraction system, stage of ripeness, and kneading temperature on the sterol composition of virgin olive oils
Author(s) -
Koutsaftakis A.,
Kotsifaki F.,
Stefanoudaki E.
Publication year - 1999
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-999-0188-y
Subject(s) - stigmasterol , campesterol , sterol , ripeness , extraction (chemistry) , chemistry , composition (language) , ripening , botany , chromatography , food science , horticulture , biology , cholesterol , biochemistry , philosophy , linguistics
Comparative extraction trials were carried out among a classical pressing, a dual‐, and a three‐phase centrifugation system using olive crops of Koroneiki variety. Two different kneading temperatures, 30 and 45°C, were tested at three stages of ripeness for two consecutive years of harvest, 1995–1996 and 1996–1997. Composition of the sterol fraction was determined in the resulting olive oil samples ( n =72). Stigmasterol was found to be affected by the extraction system; it was obtained in the highest amount in the pressing system. The ratio campesterol/stigmasterol was significantly higher in oils extracted by dual‐ and three‐phase centrifugation. Sterols were significantly affected by the ripening stage of the fruit. During December, the ratio campesterol/stigmasterol reached the maximal and β‐sitosterol the minimal values; this appears to be the optimal period for harvesting the olives. Comparison of the different kneading temperatures showed that at 30°C, Δ 5 ‐avenasterol and campesterol/stigmasterol ratio reached higher values than at 45°C.