Reportedly, L-ascorbic acid is heat-stable, although L-dehydroascorbic acid is heatunstable
and decomposed. This study was conducted to elucidate details of the heat stability of
L-ascorbic acid at 40°C, 60°C, 80°C, and boiling temperature. The time course of L-ascorbic
acid concentration was examined using 4mg / ml L-ascorbic acid standard solution and lemon
juice. No significant decrease in L-ascorbic acid concentration was found for either sample when
heated at 40°C and 60°C for 120min. A gradual decrease was observed for both samples when
heated at 80°C for 90min. When 4mg / ml L-ascorbic acid standard solution and lemon juice
were heated at boiling temperatures for 90min, their respective L-ascorbic acid concentrations
decreased considerably to 47.8% and 40.0%. The residual rate found for lemon juice was low.
Results indicated that L-ascorbic acid is stable even when heated up to 60°C for 120min. Results
also showed that the L-ascorbic acid concentration can be reduced to less than half when heated
up at boiling temperature for 90min.
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