Effects of cooking on rutin and glutathione concentrations and antioxidant activity of green asparagus (Asparagus officinalis) spears

• We cooked asparagus by six different methods.
• Changes to health-beneficial antioxidant concentrations were measured.
• Rutin is heat-stable but can be leached during water-based cooking.
• Glutathione is susceptible to high temperatures.
• Minimizing cooking duration is generally preferable to maximize health benefits.

Green asparagus spears are a good source of phytochemical antioxidants which may positively affect human health. Cooking conditions should be optimized for retention and availability of beneficial compounds in order to benefit consumers. The objectives of this study were to identify the cooking method(s) and duration(s) that allow the greatest retention of rutin and glutathione and antioxidant activity. Spears were baked, boiled, pan-fried, grilled, microwaved, and steamed, each for three durations, and compared to raw spears. Rutin was heat-stable for all methods and durations, but boiling leached up to 22% of that found in uncooked spears. Glutathione concentrations decreased with increasing cooking duration for methods using dry heat: baking, pan-frying, and grilling. Antioxidant activity increased or remained unchanged after cooking regardless of method or duration. The results suggest that green asparagus is moderately resistant to phytochemical losses during cooking, though minimizing duration may optimize the benefits from consumption.