Effect of Thermal Processing on Quality and Physicochemical Properties of Oil from Improved Groundnut Seed Varieties

Abstract

Groundnut is among the top four major sources of oil worldwide providing high quality of dietary sources for consumers. Different improved groundnut varieties were released from research centers occasionally and basic information are required to be done. This work is designed to determine the physico-chemical characterstics of newly released varieties of groundnut and their oils. Groundnut varieties (Baha-Jidu, Baha-Gudo, Tole 1, Fetene and Werer 963)in two status (roasted and un roasted) were studed. The results indicate that all proximate compositions, except moisture content, were found significantly (P≤0.05)different among the varieties. Extraction yield was highest in Tole 1 and Baha-Gudo variety with 51.85% and 50.79%, respectively. Unlike caroteinoid and minerals, Tanins and phenols significantly varies among the varieties. The color (La*b*) of the oil was unchanged with varieties and also unaffected by the roasting operation. With the exception of RI, all Physicochemical properties of the oil such as Pv, IV, SaV, AV, Sp.g, flash point, smoke point and fire point showed significant(P≤0.05) differences among the varieties. Oil yield was significantly influenced due to roasting and it showed an increment in yield from 46.9 to 52.3%. All the proximate compositions were significantly different between the roasted and unroasted. Except ash and carbohydrate, the remaining proximate compositions showed decrese for roasted seeds. Physico-chemical properties of the oil, except Werer 963, are different between the two roasting conditions. The Pv, IV, SaV, RI, AV, Sp.g, smoke, flash, fire point and viscosity showed a change from 3.58-4.00, 88.7-88.1, 183.8-185.2, 1.47- 1.46, 2.29-3.53, 0.92-0.91, 193.3-191.3, 335.5-337.6, 352.7-346.5, 55.2-53.8, respectively. Interaction between the varieties and roasting conditions also showed a significant (P≤0.05) differences. The study revealed that all the physico-chemical compositions were within the acceptable range. Hence, the groundnut varieties released recently can be used as a good raw material for commercial oil production. The study also provided basic information about the newly released varieties for further study