Physical and chemical changes in fruit of seven avocado cultivars at Mildura

Abstract

The pre- and post-harvest changes of seven different avocado cultivars were determined and evaluated as indicators of maturity.

All cultivars had similar trends in their growth. These trends continued during development, accompanied by reductions in moisture and free fatty acid contents, increases in oil content, and variable changes in ash content. Decreases in moisture content during maturity were negatively correlated with oil content. A relationship was found between oil content and seed weight.

It is suggested that the moisture content and/or seed weight could be used by the growers to estimate oil content and therefore the best time for picking. Oil content (Y) could be calculated from one of the following equations: Y = 0.19x – 1.57 where x is the seed weight (g); or Y = 90.87 – 0.77x, where x is the percentage of moisture in the mesocarp.

Taking into account the differences between the cultivars and the limited nature of the results, and on the basis of a minimum oil content of 8% as the crude fat extract, it is suggested that under local conditions, Zutano could best be picked in May, Fuerte in July, and Hazzard in September, with other cultivars to be picked between July and September. In this way a continuous supply of avocado from May to September, and even later, could be provided.