The formation of polarographically reducible substances in autoxidizing lard

Abstract

SummaryIn a polarographic study of lard during the early stages of autoxidation at 55° and 100°C. three reduction potentials were observed, and curves were plotted from the diffusion current values at the corresponding half‐wave potential to show the changes in concentration of each of the reducible substances with time. All three curves followed the general pattern of the peroxide value, determined titrimetrically. However Curve A (E 1/2=−0.15 v.) reached a maximum much earlier than either Curve B (E 1/2=−0.68 v.) or Curve C (E 1/2=−1.10 v.). Pro‐oxidants steepened the curves; antioxidants introduced a lag phase. Although the relative heights shifted somewhat, three curves persisted under all conditions. It is concluded that autoxidizing lard contains at least three types of primary “peroxidic” compounds and that these are not changed qualitatively by the presence of prooxidants and antioxidants.