Effect of processing treatments on the phytochemical composition of asparagus (Asparagus officinalis L.) juice

Asparagus (Asparagus officinalis L.) is a widely consumed vegetable with high nutritional value and health benefits. However, little is known about how different processing treatments affect the nutritional and phytochemical composition of asparagus juice. This study investigated the effects of physical, thermal, and enzymatic juicing treatments on the nutritional and phytochemical composition (phenolic compounds, protodioscin, amino acids, and volatile organic compounds (VOCs)) of asparagus juices prepared from green and white asparagus spears. Both asparagus type and processing method affected the nutrient and phytochemical composition. Green asparagus juices contained more phenolic compounds and amino acids, whereas white asparagus juices were enriched with protodioscin. The type and content of VOCs also differed with asparagus type. Physical processing was favorable for amino acid retention. Thermal treatment significantly increased the phenolic and VOC contents in green asparagus juice. Enzymatic treatment optimized the juice yield and protodioscin extraction from both green and white asparagus (0.46 and 22.59 mg/g, respectively), but significantly reduced the phenolic and amino acid contents and altered the VOCs. Our results indicate that green asparagus has desirable properties for juice production, particularly with appropriate thermal treatment.