Effect of high temperature short time infrared roasting of peanuts

Abstract

Roasting is the most common processing method that enhances color, and texture. In this study, infrared roasting of peanuts was done using an infrared rotary dryer. Roasting was operated at 90% infrared power (630 W) with different rotating speed (1 and 2 r/min). The effect of roasting was studied at different moisture levels (7.66%, 11.49%, and 13.72% db). From the study, the color parameter, L* value, was found to be significantly different (P < 0.05), and it decreased with the decrease in rotating speed, and the ∆E value varies from 2.32 to 10.56. Results also showed that the antioxidant activity decreased with the reduction in rotating speed as lesser revolutions took longer roasting time, and the values decreased from 84.34% to 71.74%. Minimal changes in total phenolic content were found and varied from 3.62 to 2.10 mg/g GAE, an appropriate limit for good-quality roasted peanuts. The hardness of roasted peanuts ranged from 12.25 to 39.43 N. Moisture content 13.72%, and 1 r/min is the best possible treatment for infrared peanut roasting, significantly enhancing the quality of peanuts. This study concluded that high-power short-time infrared roasting could give good-quality roasted peanuts with optimum bioactive compounds.