ABSTRACT
Sweet sorghum can be used to produce a substantial quantity of biofuel due to its high biological yield and high carbohydrate content. In this study, we investigated the dynamic changes in fermentation characteristics, carbohydrate components, and the bacterial community during the ensiling of wilted and unwilted sweet sorghum. The results revealed a rapid fermentation pattern and high-quality fermentation quality in wilted and unwilted sweet sorghum, wherein lactic acid, and acetic acid accumulated and stabilized during the initial 9 days of ensiling, with the pH values less than 4.2, until 60 days of ensiling. We found that the ensiling of sweet sorghum involved the degradation (5% ~ 10%) of neutral detergent fiber (NDF) and hemicellulose and that the degradation of NDF fit a first-order exponential decay model. A shift in dominance from Lactococcus to Lactobacillus occurred before the first 9 days of ensiling, and the abundance of Lactobacillus (r = -0.68, p < 0.001) was negatively correlated with the NDF content. The relative abundances of Lactobacillus in wilted and unwilted sweet sorghum after ensiling for 60 days were 76.30 and 93.49%, respectively, and relatively high fermentation quality was obtained. In summary, ensiling is proposed as a biological pretreatment for sweet sorghum for subsequent biofuel production, and unlike other materials, sweet sorghum quickly achieves good fermentation quality and has great potential for bioresource production.
ABSTRACT
Objectives: The objective of this study was to investigate the effect of different harvest times and processing methods on the B vitamins and α-tocopherol contents of Leymus chinensis (Trin.). Methods: L. chinensis was harvested on 11 July (T1 group), 16 July (T2 group), 21 July (T3 group), 26 July (T4 group), and 31 July (T5 group) in 2022 and processed using natural drying and silage fermentation to evaluate fermentation quality, chemical composition, in vitro digestibility and vitamin content. Results: The fermentation quality of L. chinensis silage prepared at all five times of harvest was better. The silage fermentation group showed a significant increase (p < 0.05) in crude protein (CP), thiamin, riboflavin, pyridoxine and α-tocopherol content, a significant decrease (p < 0.05) in water-soluble carbohydrate (WSC) content, and small differences in neutral detergent fibre (NDF), acid detergent fibre (ADF), niacin and pantothenic acid content, when compared to the natural drying group. The content of thiamine, riboflavin, niacin, pantothenic acid and pyridoxine were higher in the pre-harvest period. In silage fermentation, the loss rate of thiamin, riboflavin and pyridoxine was positively correlated with pH and WSC, and the loss rate of thiamin and riboflavin was negatively correlated with lactic acid content. The loss rate of pantothenic acid was negatively correlated with pH and WSC, and positively correlated with lactic acid and ammonia nitrogen. The rate of α-tocopherol synthesis exceeded the rate of catabolism. Conclusion: The content of CP, thiamine, riboflavin, niacin, pantothenic acid and pyridoxine were higher during the early harvest period. Silage fermentation preserved the chemical composition and vitamin content of L. chinensis better than natural drying and had no effect on in vitro digestibility. During silage fermentation, the acidic environment promoted the preservation of thiamin, riboflavin and pyridoxine, but promoted the breakdown of pantothenic acid, α-tocopherol content increased through synthesis.