Determination of ascorbic acid and effect of chilled and frozen storage on ascorbic acid content in edible bamboo shoots / Farah Izianiwati Khalib

This study was conducted to determine the content of ascorbic acid in four selected species edible bamboo shoots. Each of the specie was divided into top and bottom portions and stored at chilled and frozen temperatures. There were two methods that were used for ascorbic acid determination, which were the titration method and UV Spectrophotometer method. The results obtained indicated that for top and bottom portions of bamboo shoots stored at chilled and frozen temperatures, buluh betong (Dendrocalamus asper) and/or buluh beting (Gigantochloa levis) had significantly higher amounts of ascorbic acid than those in buluh berang (Gigantochloa brang) and buluh semantan (Gigantochloa scortechinii) (p < 0.05). It was found that were significant differences in ascorbic acid content between the bottom and top portions (p < 0.05). At the fourth week at chilled temperature, ascorbic acid content for the bottom portions of buluh beting (Gigantochloa levis) (8.89 mg/lOOg) was significantly higher than the top portion (7.78 mg/lOOg). Storage time had an effect on the content of ascorbic acid in all bamboo shoots species when determined by the titration method. For example, ascorbic acid content for the top portion of buluh betong (Dendrocalamus asper) when stored at frozen temperature in week 0 (day 2) was 12.22 mg/lOOg and the value decreased to 6.95 mg/lOOg at week 10. Storage temperature also had an effect on ascorbic acid content in four species of bamboo shoots for top and bottom portions from week 0 (day 2) until week 10. The results indicated that all bamboo shoots species stored under frozen temperature contained more ascorbic acid than those stored under chilled temperature. There were significant differences between ascorbic acid content obtained by titration and UV spectrophotometer method (p < 0.05). As an example, ascorbic acid content at chilled temperature in buluh betong (Dendrocalamus asper) for top portion by using the titration method was 7.22 mg/lOOg while the UV spectrophotometer method gave 6.26 mg/lOOg for the same portion. From this study, it can be concluded that UV spectrophotometer method gave similar results to those of the titration method. Therefore the UV Spectrophotometer method can be adopted for the routine determination of ascorbic acid in bamboo shoots and possibly in other food samples.