A non-destructive test for determination of optimum maturity of French (green) beans.

Optimal maturity stage of Burpee Stringless Variety of French (green)
beans was determined by a trained sensory panel using beans harvested
at definite intervals of growth till over-maturity. Of the changes in ten
physico-chemical characteristics studied during growth, weight to length
(W/L) ratio is closely related to the sensory characteristics and can be
used as a simple non-destructive test for determining the optimal maturity.
The beans are very tender up to a W/L ratio of 0.4 g/cm, tender
from 0.41 to 0.5 g/cm which is optimal mature stage, mature from 0.51
to 0.6 g/cm, and over-mature thereafter.
The maximum force required to cut the bean by placing on its edge
or flat in the triangular slot of the Warner-Bratzler shear press was 9.0
kg in tender beans and could be made use of as an instrumental method
for determining the maturity. The force required to cut the beans edgewise
was more than in the flat position at or before the optimal maturity
and the values reversed thereafter.
Changes in total solids, alcohol insoluble solids and fibrous matter contents
between tender and mature ones are too sudden and large during
the short transition period for being used as objective method(s) but
yielded meaningful data when considered along with W/L ratio or shear
force.