Evaluation of the Effect of Thermal Radiation on the Physicochemical Propertiesof Improved Cassava Cultivars (Esculenta Crantz) and Roasted Gari in South-South Nigeria

摘要

Three improved variety of cassava cultivars grown within 2 km flare distance in Rumuekpe flow station of Rivers State were studied for the effect of thermal radiation on the physiochemical properties and sensory parameters. The cassavas for the studies were coded NR-8082, NR-84292, and TMS-30572. The plots were designed according to distances: 0-150m, 150-300m, 300-450m, 450-600m and 1000-2000m. Randomised complete block design (RCBD) with three (3) treatments in five replications was used. The results showed that at 0-150m, 450 -600m and 1000 -2000m,the thermal radiation was (603.84w/m 2 ),(448.91±5.37d w/m 2 ,) and (428.83±0.79ew/m 2 ) respectively. At radiation level of 603.84±5.76a, the moisture content of raw cassava ranged from 56.5-57.4% for all the cultivars, while protein values (1.18-1.31%), Total carbohydrate (35.0 - 36.6%) for all cultivars. At the control radiation level 428.83±0.79e, moisture values (64.2-71.4%), protein (2.00-2.30%), Total carbohydrate (17.8- 27.6 %) for all cultivars. The proximate composition showed that moisture content of gari: TMS-30572 (9.5%), (NR-8082 (9.0%), NR-84292 (9.8%), Protein values, TMS-30572 (1.15%), NR-8082 (1.10%), and NR-84292 (1.20%). The fat content of gari ranged from (0.5 to 0.60) for NR- 84292, NR-8082 and TMS -30572.Ash content, NR-84292 (1.70%), TMS-30572 (1.90%), and NR-8082 (2.0%). Total carbohydrate, NR-84292 (8 5.25%), NR-8082 (85.20%), TMS -30572 (85.00%) with Thermal radiation (603.84±5.76a), whilst at radiation level (428.83±0.79e), Moisture content of gari : TMS-30572 ( 9.9%), NR- 8082 ( 9.8%), NR-84292 ( 9.8%), Protein values The effect of thermal stress was significant on the proximate composition (P . 0.001) at 0-150m flare distance for both raw and roasted gari. The percentage starch content for three cultivars are NR-8082 (37.34%), NR-84292 (40.7%), and TMS -30572 (39.09%), with cultivar's NR- 84292 (40.7%) having the highest starch value. The residual cyanide level of roasted gari was determined (Mg HCN equivalent Kg -1 ), NR-84292 (13.24), NR-84292 (28.16), and TMS-30572 (24.18). The highest level of reduction was NR-84292 (82.58%), least was TMS-30572 (79.46%) and NR-8082 (80.98%). P H decreases from 6.94 to 4.08 and 3.8 in 72 hours for pulp and gari for TMS-30572. P H for NR-84292 (6.66 to 4.05 and 3.8), NR- 8082, pH decreases from (6.92 to 4.10 and 3.80) for pulp and gari at 72 hours fermentation process that shows significant effect. The pH of fermenting cassava pulp and roasted gari decreases, while the titratable acidity increases as the fermentation progressed. The value of the relative bulk density, swelling index and water absorption capacity increases as the distance from the flare increases. Sensory evaluation of gari from TMS - 30572 and NR-8082 with high yield were preferred in overall general acceptability to NR-84292.Correlation analysis of the proximate composition, physiochemical properties and sensory evaluation of gari showed significant relationship at 300-2000M flare distance. It was evident in the overall study that the effect of thermal radiation on cassava performance shows significant effect.