Effect of different cooking methods on S-Alk(en)yl-L-cysteine sulfoxides profile and antiplatelet activity of onion

Abstract

• Onions are predominant with organosulfur and phenolic compounds endowed with promising functional effects. • Different cooking methods effects on organosulfur composition and bioactivities of onions. • Cooking methods altered the organosulfur content and antiplatelet activity of onions. • Stir-frying cooking was found effective to retain the high amount organosulfur compounds in onion. • Onion extracts showed significant inhibition on collagen-induced antiplatelet activity. Onions are a significant source of organosulfur compounds with promising biological effects. However, the effects of different cooking methods on organosulfur composition and biological properties in onions remain unclear. Therefore, the objective of this study was to determine the composition of organosulfur compounds and the antiplatelet effect of six different onion varieties processed using different cooking methods (boiling, stir-frying, and steaming).The organosulfur compounds were quantified by measuring the S-Alk(en)ey-L-cysteine sulfoxides (ACSOs) contents utilizing and high-pressure liquid chromatography (HPLC). Results showed no significant differences in ACSOs contents among onion varieties. However, ‘Guigum' (GG) and ‘Turbo’ (TB) varieties showed the highest amount of ACSOs at 100.6 and 98.0 mg/100 g fresh weight (FW), respectively. Total ACSOs contents in the other four varieties were 62.7∼72.4 mg/100g FW, showing similar contents. Stir-fried (without the addition of water) onions retained the highest content of total ACSO, followed by steamed treated onions. However, with the boiling method, sulfur compounds were eluted and lost in the cooking water, resulted in a 46.8% loss of ACSOs. Onion extracts showed significant inhibition of the collagen-induced aggregation of rat blood platelets. The highest effect of platelet aggregation was observed in stir-fried onion extracts, whereas the lowest was in boiled extracts. Results demonstrated that stir-frying is an effective cooking method to retain the highest amount of health-beneficial organosulfur compounds in onion.