Abstract:
Objective: This study investigated the effects of different drying methods on the quality and microstructure of
Triarrhena lutarioriparia shoots to provide a reference for their drying processing. Methods: Fresh
Triarrhena lutarioriparia shoots were divided into blanched and non-blanched groups and subjected to four drying methods: hot air drying (HAD), infrared drying (IFD), heat pump drying (HPD), and vacuum freeze drying (VFD). The effects of these drying methods on the quality attributes (texture, color, total phenols, total flavonoids, DPPH radical scavenging activity, soluble sugar content, soluble protein content) and microstructure of the samples were studied. Results: Significant differences were observed in the physical properties of dried products obtained by different methods. VFD resulted in the best physical characteristics, with the lowest shrinkage rate (9.1%), hardness after rehydration (14.2 N), and the highest rehydration ratio (5.87). IFD led to the highest shrinkage rate, but its rehydration ratio and rehydrated hardness were superior to those of HAD. In terms of nutrient retention, VFD samples exhibited the highest total phenol content (8.211 mg/g), total flavonoid content (2.482 mg/g), soluble sugar content (9.960 g/100 g), soluble protein content (12.005 mg/g), and DPPH radical scavenging rate (92.77%). Nutrient preservation capacity followed the order: VFD > IFD > HPD > HAD. Among the four methods, blanched samples showed better color but inferior physical properties and nutrient retention compared to non-blanched samples. Microstructural analysis revealed that VFD samples exhibited a porous honeycomb network structure with numerous small pores, indicating well-preserved cellular morphology with minimal damage. In contrast, HAD samples suffered severe structural collapse with the most significant damage. Conclusion: VFD is the optimal drying method for high-quality dried
Triarrhena lutarioriparia shoots. IFD outperforms HAD and HPD in nutrient preservation. Blanching effectively improves color preservation but reduces nutritional quality. This study provides valuable reference and fundamental data for further deep processing of fresh
Triarrhena lutarioriparia shoots.