The standard protocol these days for determining maturity of avocados is using DRY WEIGHT not oil.  There is a very close relationship between oil and dry matter.  The switch for the California industry came in the mid-80’s when the protocol for oil determination, the Hallowax method, was deemed carcinogenic.  Most industries now use dry matter although some industries will report in oil content since there is such a close correlation.  They do this by generating a regression analysis and using the regression equation to determine oil after determining the dry matter.

Basically dry matter is very easy to determine.  All you need is freshly harvested fruit, a scale that can measure to 0.01 g and a good microwave oven.

The California state standard protocol for dry weight determination changed in 2001.  I have pasted below the link to the article which describes this method in great detail comparing it to the older method.   I also have provided the link to the 1983 paper which served as the foundation for our current use of dry weight.  These papers and others pertaining to avocado maturity determination can be found at www.avocadosource.com.  Use the search function to look at articles on this topic.

Sampling paper for current California method:

http://www.avocadosource.com/CAS_Yearbooks/CAS_85_2001/CAS_2001_PG_153-178.pdf

The “foundation” paper:

http://www.avocadosource.com/Journals/ASHS/ASHS_1983_108_PG_390-394.pdf

-Mary Lu Arpaia