Stability of anthocyanins and sugars during heating for low sugar meoru (Vitis coignetiea) jam-making under singlet oxygen

摘要

Stability of meoru (Vitis coignetiea) anthocyanins during heating under singlet oxygen to simulate low sugar meoru jam-making was studied. Samples consisted of meoru juice, sugars (sucrose, glucose, or fructose), and pectin were placed at 10 or 90°C under singlet oxygen which was produced with riboflavin under 5,500 lx. Anthocyanins present in samples were malvidin-3,5-diglucoside, delphinidin-3-glucoside, cyanidin-3,5-diglucoside, malvidin-3-glucoside, and cyanidin-3-glucoside in a decreasing order. Meoru anthocyanins were degraded under singlet oxygen and heating accelerated the degradation. Degradation was faster in monoglucoside anthocyanins than diglucoside anthocyanins, and in samples added with sucrose or fructose than in samples with glucose. Sucrose in samples was hydrolyzed to glucose and fructose possibly by acid present in meoru, at higher rate at 90°C than at 10°C. Simple sugars added or produced by hydrolysis of sucrose were stable during heating or at 10°C under singlet oxygen, possibly due to quenching activity of meoru anthocyanins on singlet oxygen.