Effects of temperature and heating time on the formation of aldehydes during the frying process of clam assessed by an HPLC-MS/MS method

This study aimed at investigating the formation and accumulation of 16 reactive aldehydes in clam (Ruditapes philippinarum) during oil frying in both the tissue and the oil using an HPLC-ESI-MS/MS methodology. After processing, the accumulation of acrolein, crotonaldehyde, pentanal, trans-2-hexenal, hexanal, trans, trans-2,4-heptadienal, heptanal, nonanal, trans, trans-2,4-decadienal and 4-hydroxy-2-nonenal was most noticeable in both fried clam and frying oil. Most of the aldehyde species showed a time- and temperature-dependent manner of formation and accumulation during frying due to continuous oxidative degradation under conditions employed. However, several species of aldehyde such as acrolein and trans-2-pentenal slightly decreased at higher temperatures and/or longer frying times, which may be due to the imbalance toward disappearance of aldehydes resulting from their evaporation under the extreme conditions. Presence of natural polyphenols in bamboo leaves significantly prevented the formation of aldehydes in both fried clam and frying oil due to their antioxidant activity (P < 0.05).