QUANTIFICATION OF TOTAL DIETARY CHOLINE CONTENT IN FOODS AFTER HYDROLYSIS WITH PHOSPHOLIPASE D IN COMPARISON WITH ACID HYDROLYSIS

A previously we have developed a method for choline quantification that have been based on acid hydrolysis. In this study, a simple hydrolysis procedure for phospholipids in foods using only phospholipase D (PLD) was developed. Choline was extracted into a homogenized phase using chloroform/methanol/water and hydrolyzed using PLD (1:2:0.8). Choline was fully released from the phospholipids after incubation with PLD in the presence of diethyl ether as catalyzing agents. The established acid hydrolysis method and the developed PLD hydrolysis procedure was used for choline quantification in different food matrices and the results were compared. Quantitative results for foods analyzed using both methods were comparable (R^2=0.9973). The highest choline content was found in lamb liver (360 mg/100g fresh food) and lamb kidney (316 mg/100g fresh food) followed by chicken liver (172 mg/100g fresh food). Cereals and cereal breakfast contained moderate to little content of choline (20 – 86 to mg/100g fresh foods). In canned legumes the choline content was 45 mg/100 g fresh foods.