油脂自動酸化速度の解析

概要

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The rate process of autoxidation of edible oils is expressed by an equation shown below, dP/dt=k_0M+k_1MP-2k_2P^2-k_3P where P is the concentration [mmol/kg-oil] of peroxides (peroxiradical+hydroperoxide), M is that of active methylene residues, which are not oxidized yet at time t, k_2P^2 is the formation rate of the dimer of P, and k_3P is the degradation rate of P [(mmol/kg)/day] from which secondary products come. M is given by subtracting oxidized active methylene from the total amount of it, M_<max>, in unoxidized oil, i. e., M=M_<max>-(P+2k_2&lmoustP^2dt+k_3&lmoustPdt) As M_<max> is the characteristic value for each kind of oil, the right hand side of the rate equation becomes the function of P only. Consequently, the rate constants k_0, k_1, k_2, and k_3 can be measured by the peroxide value, because P equals the peroxide value×1/2. The 1st., 2nd., 3rd., and 4th terms of the rate equation correspond to the periods of initiation, chain reaction, termination and degradation of P, respectively. By measuring the rate constants k_0, k_1, k_2, and k_3, in preservation tests of oils under various conditions (ex. temperature, light), we can estimate the effects of the conditions on autoxidation rate. For example, this paper describes how the brightness showed effects on k_0, k_1, and k_3, but that it had no effects on k_2, the formation rate constant of the dimer of P.
社団法人日本農芸化学会の論文
1996-01-01