As seen in Table 1, the oil extraction yields were invariant
at 35 ± 1% regardless of the acetone concentration in the solvent
mixture. However, total and free gossypol levels in the
meal changed significantly with increased acetone concentration.
More than 50% removal of total gossypol and 90% removal
of free gossypol were achieved by extraction with the
solvent mixture containing 25% acetone. The solvent mixture
with 10% acetone removed less free gossypol than the solvent
mixture containing 25% acetone. Nevertheless, the removal of
more than 80% of the meal free gossypol and 40% of the meal
total gossypol by extraction with the solvent with 10% acetone
was achieved, confirming the strong influence of a small
amount of acetone on the solubility of gossypol (11). The characteristic
catty odor was not detected in the meal produced with
a mixture of 10% acetone in hexane. The odor intensity of meal
produced with 25% acetone was evaluated as 2 (see Ref. 12 for a description of the intensity range). In comparison, the meal
produced by extracting with pure acetone had a strong catty
odor with an intensity level of 6, a value that is considered
strong enough to pose a problem as animal feed. These data indicate
the acetone concentration maximum that would produce
cottonseed meal without the detrimental odor lies in the range
of 10 to 20%.