Domestic cooking methods affect the stability and bioaccessibility of dark purple eggplant (Solanum melongena) phenolic compounds

Eggplant is an important component of the Mediterranean Diet, which becomes edible after cooking. This study determined the fate of dark purple eggplant phenolic compounds after baking, boiling, frying, grilling and digestion. Thirty-seven phenolic compounds were identified and quantified in raw eggplant. Frying determined a 74% increase in total hydroxycinnamic acids whereas a decrease was observed after boiling (27%), grilling (51%), and baking (60%). After digestion, 45%, 33% and 22% of total phenolic compounds resulted bioaccessible in baked, grilled and fried dark purple eggplant. Fried eggplant displayed the highest amount of phenolic compounds (751.46 mg/100 g) after digestion. The cooking methods differently affected the release of individual phenolic compounds. Baking and grilling resulted in higher amount of bioaccessible caffeoylquinic acids whereas frying in di-caffeoylquinic acids and hydroxycinnamic acid-amides. A careful design of the cooking method may be pivotal to modulate the release of specific phenolic compounds.