Influence of High-Voltage Corona Discharge on Drying Kinetics and Physicochemical Properties of Alfalfa at Various Air-Gap Spacings

Abstract

The high nutritional value of alfalfa hay makes it a widely utilized component in animal feed. However, the current prevalent drying methods for forage have a significantly detrimental impact on the quality of alfalfa during the drying process. This study investigates the effects of high-voltage corona discharge (HVCD) treatment on post-cut alfalfa. Gradient experiments are conducted by adjusting the air-gap spacing at a voltage of 25 kV. The results demonstrate that as the distance decreases, there is an observed increase in the drying rate, rehydration rate, and color intensity of the HVCD-treated material. HVCD treatment significantly enhances crude protein content, which increases with decreasing air-gap spacing. Meanwhile, it negatively affects lignin, neutral detergent fiber (NDF), and acid detergent fiber (ADF) levels. The relative forage quality (RFQ) of alfalfa reaches its peak at an air-gap spacing of 7 cm. The application of HVCD disrupts the fiber structure and induces significant electroporation effects in cells. Minimal changes in functional groups preserve nutrient integrity. Furthermore, HVCD exhibits lower energy consumption compared to hot air dryers. The HVCD treatment is a highly efficient and effective method, with a gradual improvement in alfalfa hay quality as the air-gap distance decreases.