Effect of enzymatic application on borage (Borago officinalis) oil extraction by cold pressing

Synthesis of γ-linolenic acid (GLA) from linoleic acid (LA) is less than 10% in the human body. GLA is changed into di-homo-γ-linolenic acid (DHGLA), a prostaglandin 1 (PGE1) precursor. PGE1 has anti-inflammatory and anti-thrombotic properties. Due to these facts, supplements of GLA in a diet can alleviate the resulting health problems as platelet aggregation, arthritis and spleen constriction/dilation. Borage (Borago officinalis) seed has a high oil content (30% d.w.b.), which is the richest source of γ-linolenic acid (GLA), with 24% GLA. Cold pressing borage oil extraction, does not harm the final product quality, but its yield (about 77%) is lower than 100% yield of traditional oil extraction processes by solvent application. However, according to fibre composition (cellulose, 29% and 5.6% of pectin), it is possible to increase oil extraction yield, using enzymes with pectinases and cellulases activities prior to the pressing stage. In this work, press extraction of borage seed oil was evaluated using an enzymatic pretreatment. Nine commercial enzymes were studied individually and combined. Hydrolysis was performed at pre-selected conditions. Extraction yield was determined measuring the press-cake residual oil by the Soxhlet method. Best results have been obtained by Celluclast-Olivex (1:1) enzyme mixture (cellulase - pectinase), 84% extraction yield with 0.5% d.b. enzyme-substrate ratio. It is concluded that a preliminary enhancement of 8% oil recovery by enzymatic process is relevant due to borage oil's high commercial value.