Preparation, evaluation and functional properties of gossypol-poor cottonseed protein isolates

Abstract

The glanded cottonseed ( Gossypol barbadense, variety Ashmouni) was used in the present study. The location, distribution and properties of the most important constituents of the seeds, namely protein, oil and gossypol were examined. Four treatments were used to prepare gossypol-poor flour from the cottonseed. Treatment I depended on differential settling using fresh hexane in all different steps. The process was repeated to prepare different fractions of gossypol-poor flour. Treatment II was similar to I except that fresh hexane was used only in the first step and the produced oil-hexane miscella was used in the subsequent steps. Treatments III and IV depended on a combination of sieving (200 mesh sieve) and the differential settling process. For treatment III the residual flour was ground, sieved and used to prepare fractions of gossypol-poor flour using fresh hexane. The oil-hexane miscella was used in treatment IV. The four treatments can be arranged in the following decreasing order according to the amount of edible protein obtained from 100g of dehulled cottonseed: III > I > IV > II. Three protein isolates, namely A, B and D' were obtained from treatment III giving a recovery of 21.2% of edible flour from dehulled cottonseed, i.e. 66% of the original protein present in the Ashmouni cottonseed variety. The protein isolates obtained were evaluated for nitrogen extractability as well as some chemical, nutritional and physicochemical properties. The results illustrate the possibility of using the prepared protein isolates as thickening and whipping agents, emulsifiers and extenders in different food products.