Cholesterol oxidation products in traditional Mexican foods

Cholesterol oxidation products (COPs) have been identified as the primary factor that triggers the atherosclerotic lesion. A number of studies have demostrated that COPs are capable of affecting tissues in both animal and in vitro studies. Although a number of works have reported the presence of COPs in dried foods such as milk and eggs, other high-risk foods have not been evaluated. These include widely consumed food products in México as sun dried beef and shrimp and deep-fried pork rinds. The aim of this study was to analyze the content of COPs of cholesterol containing, commercially produced foods that are considered high risk for having undergone extensive oxidative changes during their processing. Samples of sun dried shrimp and beef (machaca), as well as deep fried pork rinds (chicharron) were obtained from the local market. Lipids were extracted by the Folch’s method , then subjected to cold saponification, purified by solid phase extraction using aminopropyl columns, silanized and injected in gas chromatography. The samples of dried shrimp, dried beef and fried pork rinds contained 2.0, 12.7 and 50.9% of total lipids. Cholesterol constituted 3.6, 0.052 and 0.106% weight of the foodstuffs. COPs represented 12.4, 0.43 and 0.07 mg/g lipid of the dried shrimp, beef and pork rinds samples. The isomers 7alpha-hydroxycholesterol, 7beta-hydroxycholesterol and 7-ketocholestrol, were the most abundant COPs found. The content of COPs in the products analyzed are considered as typical of animal foods that become prone to oxidation due to their processing, handling or storage. In particular, sun-drying of shrimp generated free radicals and reaction conditions that induced oxidative changes in the cholesterol molecule, which resulted in veryhigh levels of COPs