Rheological and sensory properties of rice varieties from Improvement Programmes in Ghana

The physical, rheological and sensory properties of six rice (Oryza sativa) varieties, from two improvement programmes in Ghana, were evaluated with the aim of establishing their specific food uses. The varieties were Ex-Baika, Bouake, Ex-USA, Local perfumed, Rustic and Tox 3233-31-6-2. Sensory evaluation and consumer acceptability of both the raw and cooked form of varieties were conducted using trained panellists with a US No. 5 market sample as control. The mean total milling recovery (TMR) ranged from 36.0 to 64.6%. Ex-USA and Local perfumed recorded the highest levels of brokens while the other varieties had minimal incidence of chalkiness and were slender in shape. Apart from grain size, slenderness and overall acceptability, there were significant differences (p < 0.05) among the mean scores of all the other attributes evaluated for raw rice. Rustic, despite its appreciable levels of both black and white specks, was the most preferred followed by Ex-Baika, Tox3233-31-6-2, Bouake, Ex-USA, Local perfumed and US No.5. All the samples with the exception of Tox 3233-31-6-2 had their viscosities increasing more than two fold at the end of the cooling period. The order of increasing tendency to gel upon cooling was US No. 5< Ex Baika< Tox 3233-31-6-2< Local perfumed < Bouake< Rustic < Ex USA. There were significant differences (p<0.05) in all the attributes of the cooked rice but overall, Ex-Baika, Bouake and Ex-USA came close to US No. 5 control sample.