EVALUATION OF PHYSICOCHEMICAL, FUNCTIONAL AND SENSORY CHARACTERISTICS OF SELECTED IMPROVED CASSAVA VARIETIES DEVELOPED THROUGH GAMMA IRRADIATION

Abstract

Cassava has significant potential for utilization and diversification at household and industrial levels. New varieties (CAS 1, CAS 2, and CAS 3) with proven high yields and disease resistance were previously developed from KME 4 through mutation breeding with gamma irradiation dose rates of 15, 20, and 30 Gy respectively administered at 2 Gy/min. However, the applicability of these varieties in ensuring food and nutrition security has not been comprehensively studied. Consequently, this study sought to evaluate the physicochemical, functional, pasting, and sensory characteristics of flour and products derived from the new cassava varieties. The tests were conducted using standard official procedures. The cassava flour exhibited high lightness (L*) and whiteness, along with low redness (a*) and yellowness (b*). Porridge displayed a lightness (L*) value indicative of a bright appearance, with a consistent yellowish hue (b*). Cookies showed distinct lightness (L*) values, with the top side of the cookies generally exhibiting higher lightness compared to the bottoms, attributed to increased browning from direct heat exposure during baking and Maillard reactions. Browning Index (BI) values reflected a greater degree of browning in the bottoms of the cookies, highlighting the impact of baking conditions on color development. The results indicated that gamma irradiation significantly (p<0.05) increased the levels of carbohydrates, magnesium, zinc, and iron. Conversely, it significantly (p<0.05) decreased the pasting properties, oil absorption, and solubility index. Overall, the cassava varieties developed through gamma irradiation recorded higher mineral content and comparable functional properties to the parent variety. Fourier transform infrared spectroscopy (FTIR) revealed stretching of O-H, C=O, C-O-H, and O-H functional groups in the flours. Water/hydroxyl groups stretching increased due to gamma irradiation leading to higher intensity of peaks in the 3800-3200 cm-1 range and it also shifted the peaks at the fingerprint region peaks 473- 927cm-1. Based on the pasting properties, KME 4 and CAS 1 are more suitable for baking products, KME4, while CAS 2 and CAS 3 are ideal for porridge preparation. Consumer acceptability for porridge was moderately favorable across all varieties, while for cookies, formulation V5 variety (50% cassava and 50% wheat) was the most preferred. In conclusion, gamma irradiation influences were varietal dependent and the products made from these flours have good overall acceptance. As a result, consumers should be enlightened about such products and their role in enhancing food and nutrition security.