Effects of the storage conditions of burdock ( Arctium lappa L.) root on the quality of heat-processed burdock sticks

Abstract

Polyethylene film and corrugated cardboard were used to package and store burdock roots ( Arctium lappa L.) at 2, 8, and 20 °C in an attempt to maintain the good appearance of heat-processed burdock sticks. The weight loss was as high as 60% of fresh weight when corrugated cardboard cartons were used for storage at 20 °C. However, polyethylene bag packaging or low temperature storage resulted in lower levels of weight loss (less than 30%). To control the formation of white solids in exudate from processed sticks, low temperatures (2 °C) and storage of burdock roots for more than 30 days before processing were used to maintain the good appearance of burdock sticks. There was a significant decline in sugar content during storage at 8 and 20 °C, corresponding to an increased production of white solids. The fructan composition of raw burdock roots decreased faster to about 60% after storage for 30 days at 2 °C than at other storage temperatures (to about 30%). Inulinase activity in burdock roots stored at 2 °C was higher than in those stored at 8 and 20 °C. The amount of muddy exudate and the sugar content in solutions surrounding burdock sticks were related to the storage temperature before processing. These results indicate that the storage of burdock roots in polyethylene film packaging for 30 days at 2 °C is suitable to prevent the formation of muddy precipitate in processed burdock sticks.