Human health-beneficial phytochemicals in asparagus (Asparagus officinalis): genetic variation and effects of cooking
Asparagus contains high concentrations of human health-beneficial compounds, notably rutin, protodioscin, and glutathione. To maximize positive effects, the potential for breeding high-phytochemical asparagus and the influence of different cooking methods on retention and antioxidant activity were assessed. Within a diverse set of clones, genetic variability was observed for rutin and analysis of progeny from a partial diallel cross suggested moderate heritability (h2 = 0.49), but glutathione and protodioscin were strongly influenced by environmental or other factors. For the cooking experiment, spears were baked, boiled, pan-fried, grilled, microwaved, and steamed, each for three different durations. Up to 22% of rutin was leached during boiling and up to 37% of glutathione was lost during pan-frying, grilling, and baking; short durations were optimal for retention. Antioxidant activities remained unchanged or increased across all methods. Overall, steaming and microwaving are best for phytochemical retention and future breeding for enhanced rutin should improve health benefits.