The grape seeds (type airen) used in this study had previously
been treated in the wine fermentation industry with
hot water in order to recover all the remaining sugars, since
this wash water is normally fermented and distilled to obtain
alcohols. As a consequence of the hot water treatment, the
total oil content of treated grape seeds is always lower than
that of untreated grape seeds [ 6-101.
The seeds were treated under a range of conditions
whereby their grinding size and subsequent drying time were
modified. The milling was carried out in a Futurmat model
FP coffee mill and the drying in a Heraeus heater at 70 “C.
To determine the conditions leading to the optimum extraction
yields, a size range of 0.35-2.83 mm and a humidity
range of 0.35%-6.50% were studied. .
Conventional extraction was carried out using hexane in a
Soxhlet apparatus for 20 h (with a fraction grape seed size
of 0.75 mm and humidity less than 0.35%) to guarantee the
maximum extraction efficiency.