Effects of Different De-enzyming Methods on Nutrition and Flavor Substances of the Dried Bamboo Shoots During Processing

【Objective】 This paper aims to study on the effects of different de-enzyming methods，such as steaming and boiling，and time durations，on the nutrition and flavor substances of bamboo shoots，so as to provide scientific basis for improving the product quality in processing dried bamboo shoots. 【Method】 The contents of protein，oxalic acid，tannin，soluble sugar and total acids in bamboo shoots after steaming and boiling for 0.0，0.5，1.0，1.5，2.0，3.0，4.0 and 5.0 h were analyzed respectively to find out effects on Moso bamboo shoots by different time durations with various treatment methods. Protein was detected with method of BCA (bicinchoninic acid)，oxalic acid was detected with method of indophenol blue colorimetry，tannin was detected with method of spectrophotometer directly，soluble sugar was detected with method of anthrone colorimetry，and the determination of total acid was carried out according to the national standard GB 12456—2021 “National Food Safety Standards，Determination of Total Acid in Foods”. The calculation of sugar-acid ratio is：sugar—acid ratio = sugar/acid. 【Result】 After steaming and boiling，the content of protein in all sample bamboo shoots was lost，and there was no evidence to prove that the significant loss of bamboo shoot protein by boiling is strongly linked to the treatment time. The content of oxalic acid of bamboo shoots by steaming was between 0.8 and 1.0 mg·g^-1，and that by boiling was about 1.0 mg·g^-1，and the control was about 0.1 mg·g^-1. The tannin content of bamboo shoots treated with steaming and boiling was about 0.38 mg·g^-1 and 0.41 mg·g^-1，respectively，that of the control was 1.2 mg·g^-1. Besides，the changes of oxalic acid and tannin contents have no correlation with the treatment time. Compared with boiling，in de-enzyming，steaming can retain more soluble sugar，the average soluble sugar of bamboo shoots by steaming was 8.82 mg·g^-1，that of boiling was 6.96 mg·g^-1，the control was 18.31 mg·g^-1. The total acid content of bamboo shoots treated with the two methods was 0.1-0.2 mg·g^-1，and the control was 0.84 mg·g^-1，which had no obvious correlation with the treatment time. 【Conclusion】 Compared with boiled bamboo shoots，the steamed bamboo shoots retain more protein，soluble sugar and less oxalic acid and tannin. Therefore，it can be speculated that in de-enzyming，steaming is better than boiling. Combined with the actual production，the assembly line of steaming can process more fresh bamboo shoots faster，reducing the time for the peeled fresh bamboo shoots to be placed at room temperature，which greatly hilight this advantage. Another conclusion is treatment time has little effect on nutrition and flavor substances.