Optimization conditions of samples saponification for tocopherol analysis

•A factorial design enabled the optimization of saponification methodology.•The most efficient concentration of KOH solution was 60% (w/v).•The most efficient agitation time was 2h.•The increasing of KOH concentration and agitation time reduces the efficiency. A full factorial design 22 (two factors at two levels) with duplicates was performed to investigate the influence of the factors agitation time (2 and 4h) and the percentage of KOH (60% and 80% w/v) in the saponification of samples for the determination of α, β and γ+δ-tocopherols. The study used samples of peanuts (cultivar armadillo), produced and marketed in Maringá, PR. The factors % KOH and agitation time were significant, and an increase in their values contributed negatively to the responses. The interaction effect was not significant for the response δ-tocopherol, and the contribution of this effect to the other responses was positive, but less than 10%. The ANOVA and response surfaces analysis showed that the most efficient saponification procedure was obtained using a 60% (w/v) solution of KOH and with an agitation time of 2h.