Cholesterol oxidation in traditional Mexican dried and deep-fried food products

A number of animal and in vitro studies have demonstrated that cholesterol oxidation products (COPs) are the primary factor that triggers the atherosclerotic lesion. Furthermore, it has been recognized that several COPs have carcinogenic, cytotoxic and mutagenic effects. Although some works have reported the presence of COPs in a number of dried and deep-fried foods, other high-risk food products have not yet been evaluated. The aim of this study was to analyze the content of COPs of three widely consumed, typical Mexican food products: deep-fried pork rinds (chicharrón), dried beef (machaca) and sun-dried shrimp, which are subjected to severe thermal treatments and have relatively high cholesterol content. Lipids were extracted according to Folch's method, then subjected to cold saponification, purified by aminopropyl solid-phase extraction, silanized and analyzed by gas chromatography. The most abundant COPs found in all samples were 7α-hydroxycholesterol, 7β-hydroxycholesterol and 7-ketocholesterol. The total amount of COPs varied from 45 to 57 mg/kg in chicharrón and machaca, whereas the sun-dried shrimp showed higher COPs content (131–254 mg/kg). The extent of cholesterol oxidation of chicharrón, machaca and sun-dried shrimp were 2.3%, 5.1% and 14.5%, respectively.