Low concentrations of acetic acid and its sodium salt enhance the anaerobic fermentation and aerobic preservation of Chinese cabbage waste

Anaerobic fermentation of Chinese cabbage waste (CCW) into animal feeds is impeded by excessive true protein degradation and high aerobic sensitivity. This study evaluated the effects of acetic acid and its sodium salt on the anaerobic fermentation and aerobic preservation of CCW. The CCW was mixed with rice bran to achieve a dry matter (DM) content of 350 g/kg fresh matter. The mixtures were then treated with acetic acid, sodium diacetate and sodium dehydroacetate, respectively, at 0.2 % fresh matter for 60 days of anaerobic fermentation and then challenged aerobically for 6 days. The results demonstrated that sodium diacetate and sodium dehydroacetate increased the water-soluble carbohydrate content (29.70 g/kg DM and 30.60 g/kg DM vs. 26.45 g/kg DM) and decreased the ammonia nitrogen content (42.40 g/kg TN and 42.73 g/kg TN vs. 59.61 g/kg TN) during anaerobic fermentation. Moreover, sodium dehydroacetate inhibited the pH value increase (3.97 vs. 4.19), lactic acid degradation (91.22 g/kg DM vs. 69.69 g/kg DM) and yeast recovery (5.02 log 10 CFU/g FM vs. 9.09 log 10 CFU/g FM) after 6 days of aerobic exposure. Sodium dehydroacetate increased Lactobacillus plantarum abundance by 73.43 % and decreased the abundance of Levilactobacillus brevis and Levilactobacillus parabrevis by 51.05 % and 89.24 %, respectively, during the anaerobic period. Moreover, sodium dehydroacetate increased the abundance of Levilactobacillus brevis and Levilactobacillus parabrevis during aerobic exposure. Overall, sodium dehydroacetate promoted the homofermentative pattern in the anaerobic stage and the heterofermentative pathway in the aerobic stage, which improved the anaerobic fermentation and aerobic preservation of CCW. • Sodium diacetate and sodium dehydroacetate promoted anaerobic fermentation quality. • Sodium dehydroacetate enhanced aerobic stability of Chinese cabbage waste (CCW) fermented feeds. • Sodium dehydroacetate improved CCW recycling by altering the microbial composition. • Low-concentration acetic acid and sodium diacetate exacerbated aerobic spoilage.