## 5 Processing Effects  
Processing effects on the activity of the bioactive compounds have been investigated. The removal of peanut skins from peanuts can involve mechanical abrasion, heat, and exposure to air. An investigation that compared hand peeling of the skins from peanuts in comparison to those from the mild heat treatment of conventional blanching and the more intense heat of roasting was compared in terms of the antioxidant properties of the peanut skin extracts [40]. Blanching was found to have a greater effect on the concentration of total phenols when compared to the roasting process. The use of ethanol was found to be a slightly more effective solvent in terms of the total phenolic content compared to methanol. To determine the processing effect on the antioxidant activity, the ABTS+ assay was used. The activity of the extracts in terms of free radical scavenging activity was found to differ with the processing effect and solvent used. For the peeled skins with no heat treatment, the activity was higher when methanol was used. For the roasted samples, the skin extract had greater activity when ethanol was used. These two systems were 10 times more effective than blanched skins regardless of the solvent used. To evaluate how peanut roasting, the most common processing procedure for peanuts, affects the bioactivity of peanut skin extracts, several procedures for removal were evaluated [117]. After peeling, blanching (light heat treatment), and roasting, the recovered skins were extracted using 80% ethanol in water solutions. Comparisons of TPC, total antioxidant activity (TAA) as free radical scavenging ability, and the DPPH assay were made. The extracts were assayed as both the crude extracts and those that had been further purified by isolating only the procyanidins. Blanching before skin removal resulted in significant losses in TPC, while roasting did not. Correspondingly, the antioxidant levels were decreased much more in the blanched over the raw peeled and roasted skins. This same pattern was reflected in the concentrations of the procyanidins recovered from the skins after process treatment. Further investigations made use of the assays already discussed to evaluate the bioactivity of peanut skin extracts but added more focused testing. The free radical and oxygen scavenging properties, along with in vitro testing using human erythrocytes was examined [118]. Treatment with ozone has been proposed as a method to reduce aflatoxin contamination in peanuts. Ozonation, however, proved to be detrimental to the phenolic compounds present in peanut skins [119]. The peanut skins were exposed to ozonation for an increasing amount of time. The skins were extracted with methanol (80% in water) using sonication as described in a previous publication [40]. After the methanol was removed, the aqueous solution was defatted with chloroform. The extract was then partitioned into ethyl acetate to recover the phenolics. The ethyl acetate was evaporated, and the extract was dissolved in methanol for analysis by HPLC-TOF-MS and total phenolic content using the Folin-Ciocalteu assay. Total flavonoids increased with ozonation time, which was attributed to the disruption of cell walls releasing the compounds from glycosides. The flavonoids and proanthocyanidins were found to decrease rapidly up to 30 min of ozone exposure and then more slowly decrease up to 60 min without being totally lost. Almost total reduction was seen after 60 h of treatment. Correspondingly, the antioxidant activity as measured by the DPPH assay was found to be reduced as well. Another process effect study subjected peanut skins to gamma irradiation before extraction with methanol alone [120]. This study drew on older research with similar legumes to peanuts [121]. The extracts were used to measure polyphenols using TPC, the amount of condensed tannins, total flavonoids as quercetin, and antioxidant activity using DPPH and ABTS. Only the total flavonoids were slightly increased by the irradiation.