Influence of microwave bag vs. conventional microwave cooking on phytochemicals of industrially and domestically processed broccoli

Abstract

Cooking vegetables in microwave bags is becoming a popular domestic cooking method, being relevant to know how this cooking method affects health-promoting phytochemicals of staples such as broccoli. The aim of this work was to study the effect of microwave bag cooking versus conventional microwaving on bioactive compound content (glucosinolates and hydroxycinnamic acid derivatives) and other quality parameters (such as antioxidant capacity, mineral content and microbial load) of broccoli florets. The influence of cooking time on bioactive compounds content was also evaluated. The study was carried out in two independent experiments; using intact broccoli and broccoli preprocessed in industry. Microwave bag cooked broccoli for 5 min (following label recommendation) showed higher glucosinolate content retention compared to conventional microwaving. Results suggest that volatilization could be an important phenomenon in reduction of glucosinolates during microwave cooking of broccoli florets. Glucosinolate profile did not change after cooking, regardless of cooking method applied. Furthermore, microwave bag cooked broccoli presented higher antioxidant capacity (by DPPH assay) than conventional microwaved broccoli. Hydroxycinnamic acid derivatives content was reduced in microwave cooking, regardless of method applied. Altogether, the use of microwave bags for microwaving is a novel method that retains main bioactive components of broccoli. This option is a fast, easy and considerably clean cooking option to fulfill modern consumer needs.

Keywords: Broccoli; Domestic processing; Glucosinolates; Industrial processing; Microwave cooking, microwave bag.