Sensory Characterization of Dominant Malawi Peanut Varieties After Roasting

Abstract

Although sensory appeal influences peanut consumption, peanut varieties are mostly selected based on agronomic traits. As a result, the sensory properties of peanut varieties, especially in southern Africa, are not known. Therefore, the primary objective of the study was to determine the sensory properties of the Malawi peanut varieties and the volatile compounds associated with roasted peanut flavor. Six dominant Malawi peanut varieties (Chalimbana, CG7, Nsinjiro, Kakoma, Baka, and Chitala) were evaluated in this study. All peanut samples were shelled and then, roasted in a convection oven to reach medium doneness as indicated by the surface color lightness (L) value of approximately 50. A hybrid descriptive analysis (DA) was done to determine the sensory profile of the roasted peanuts. Volatile compounds were extracted from equilibrated ground peanut sample using headspace-solid phase microextraction technique and analyzed by GC-MS. Analysis of Variance (ANOVA) of the DA data showed significant differences (P < 0.05) in the sensory profiles of the peanut varieties. Nsinjiro and Baka had a significantly higher intensity of roasted peanutty aroma and flavor (P < 0.05). The GC-MS results showed that pyrazines and furans were the dominant volatile compounds but, their respective concentrations, in the evaluated peanut varieties, were significantly different (P < 0.05). Among the pyrazines, 2-ethyl-3,5-dimethyl pyrazine was strongly correlated with roasted peanutty flavor (r = 0.927) just like 2,5 dimethyl pyrazine (r = 0.916). Therefore, 2-ethyl-3,5-dimethyl pyrazine and 2,5-dimethyl pyrazine production pathways could provide more insights into the origins of roasted peanut flavor. PRACTICAL APPLICATION: The findings of this study can help food product developers, who have no access to sensory and analytical analyses, to identify Malawi peanut varieties that are suitable for various food applications. Furthermore, plant breeders could also use the findings to inform new projects aimed at improving the sensory properties of the peanut varieties.