The oil content of avocado mesocarp

Four methods of analysing for oil content of avocados are compared (three with gravimetric measurements): (a) Soxhlet extraction with petroleum ether, (b) homogenisation with petroleum ether, (c) homogenisation with a 2:1 (by volume) choroform/methanol solution, and one with refractmetric measurement, i.e. (d) ball milling with 1‐chloronaphthalene. Conditions for Soxhlet extraction were optimised. Methods (a) and (b) gave similar results which were 6‐9 % lower than those of methods (c) and (d) which were similar to each other. Saponification of the residues from methods (a)‐(c) confirmed that method (c) removed more oil than methods (a) and (b) but also showed that even method (c) left some residual oil in the fruit tissues. Results are interpreted in terms of glycolipids and phospholipids remaining after extraction of triglyceride storage fractions by petroleum ether. All methods used were applicable to hard (unripe) and soft (ripe) fruits.