Chemical Changes and Oxidative Stability of Peanuts as Affected by the Dry-Blanching

The oxidative changes of peanuts subjected to the dry‐blanching process were evaluated and compared with those of their in‐shell counterparts. In general, the fatty acid profile was not influenced. The content of α‐tocopherol decreased, but the remaining tocopherol homologs were unaffected. Nonanal, an oxidation product of oleic acid, increased. However, the contents of several volatile compounds with potential antioxidant properties were also increased. The higher oxidative stability of dry‐blanched peanuts was demonstrated by accelerated tests as evaluated by peroxide value, thiobarbituric acid reactive substances (TBARS) and the induction period of cold‐pressed oils and this was confirmed by the higher antioxidant properties of oils from such sample as evaluated by the DPPH radical scavenging activity. These results were further confirmed during long‐term storage of dry‐blanched and in‐shell peanuts. The decrease of tocopherols in peanuts due to dry‐blanching did not negatively influence their oxidative stability. In fact, dry‐blanched peanuts showed higher stability as compared with in‐shell peanuts; therefore, we suggest that loss of tocopherol might be less important than the generation of several volatile antioxidant compounds as well as possibly Maillard reaction products upon the dry‐blanching process. These results may be of practical interest to the peanut and peanut oil industries.