Study on the Effects of High-Voltage Discharge Plasma Drying on the Volatile Organic Compounds and Texture Characteristics of Oat Grass

Oat grass is a high-quality forage with exceptional nutritional value and quality. Freshly harvested oat grass requires rapid drying to extend its shelf life. Currently, the primary methods for drying oat grass are natural air drying (AD) and hot air drying (HAD). However, prolonged drying times or elevated temperatures can lead to a degradation in hay quality. To address this issue, in this study, we employed a novel non-thermal drying technology—high-voltage discharge plasma drying (HVDPD)—to dry oat grass. The HVDPD device adopted a multi-needle plate electrode system, with a high-voltage power output of 50 Hz AC and a voltage set to 35 kV. The distance between the needle tip and the plate was set to 10 cm, while the spacing between the needles was adjusted only to three gradients of 2 cm, 8 cm, and 12 cm. To investigate the effects of HVDPD, HAD, and AD on the volatile compounds and textural characteristics of oat grass, in this study, we employed gas chromatography–mass spectrometry (GC-MS) for qualitative and quantitative analyses of the primary volatile components in oat hay. The texture characteristics were determined using texture profile analysis (TPA) and shear testing. A total of 103 volatile substances were detected in oat grass. We categorized them into the following: 28 types of alkanes, 17 types of alkenes, 8 types of esters, 11 types of ketones, 13 types of aldehydes, 20 types of alcohols, and 6 other classes of compounds. We found that the HVDPD group demonstrated significant advantages in enhancing the volatile flavor and palatability of oat grass. The results of the textural properties showed that the structure of oat grass treated with HVDPD was significantly softer, with the 2 cm needle-spacing group exhibiting superior quality and palatability. Overall, this research demonstrates the significant advantages of HVDPD for drying oat grass, providing an important reference for its application in the field of drying technology.