Effects Of Preprocessing,Frozen Storage And Thawing Methods On Nutrition Quality Frozen Broccoli

Broccoli (Brassica oleracea L. var. italica) is a kind of vegetable with high nutritional value as well as an unique flavor. In recent years, broccoli has attracted more attentions as a rich source of anticancer glucosinolates. Being more and more popular during foreign customers, broccoli is now a main kind of export vegetables in Zhejiang Province. As fresh broccoli has a short shelf life, people usually export frozen broccoli instead of fresh broccoli. In this study, we tend to evaluate the effect of preprocessing, frozen storage and thawing methods on frozen broccoli by investigating the changes of its nutrient quality, including the content of glucosinolates, Vitamin C, total polyphenols, soluble protein, reducing sugar and the antioxidant activity under these conditions. The results are as follows:1) Preprocessing treatments before freezing caused a magnificent decline on the nutrient quality of broccoli. The loss in quality mainly happened during blanching and the following cooling treatment. We may minimize it by improving blanching and cooling techniques.2) Glucosinolates content in frozen broccoli was quite stable during the storage at-20℃, only with a slight decrease after170days storage. This makes frozen broccoli potential as an anticancer vegetable.3) Thawing methods had a great influence on the quality of frozen broccoli. Frozen broccoli thawed in4℃fridge achieved the best effect in maintaining the nutrient quality when compared with other methods.