Thermal conditions and active substance stability affect the isomerization and degradation of lycopene

Abstract

This study evaluated the effects of thermal treatment conditions (100-120 °C, 0-5 h) and active substance stability on the isomerization and degradation of lycopene in the "Sanhong" pummelo (C. grandis cv. Sanhongmiyou) matrix. The results revealed that the degradation of (all-E)-lycopene and total lycopene in pummelo could be well fit by the first-order kinetic model under thermal treatment. The total Z-lycopene ratio was maintained at nearly 40 % (120 °C, 4 h). The behavior of lycopene was related to the degradation of active substances, such as the degradation of ascorbic acid and polysaccharides. The stability of polysaccharides was temperature-dependent, and with the increasing temperature (100-120 °C), a significant negative correlation was observed between the content of Z-isomers and polysaccharides. The enhancement of lycopene isomerization was attributed to the degradation of polysaccharides under thermal treatment. These findings facilitate the functional development and efficient utilization of lycopene in fruit processing.

Keywords: Ascorbic acid; Matrix; Naringin; Polysaccharide; “Sanhong” pummelo (C. grandis).