Effect of Vacuum Concentration on Nutritive Quality and Flavor of Green Asparagus Juice
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Abstract:
To explore the effect of vacuum concentration on the nutritive quality and flavor of green asparagus juice, fresh juice was vacuum concentrated at 50 ℃ and 0.1 MPa. Four kinds of concentrated juice were obtained with soluble solid content of 10%, 20%, 30%, and 45%, respectively. The color, vitamin C content, total sugar content, total phenolic content, and flavonoid content were determined in the concentrated and fresh juice samples. Volatile flavoring compounds in the asparagus juice samples were comparatively analyzed by headspace solid-phase micro extraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The results showed that vacuum concentration significantly affected the nutritive quality and flavoring compounds in green asparagus juice. As the soluble solid content increased, the color of the juice became dark-green, the vitamin C and total flavonoid contents decreased, and the total sugar and total phenolic contents increased. The main volatile compounds of green asparagus juice were found to be aldehydes, ketones, and alcohols. As the soluble solid content in the juice increased, the flavoring compound content first increased and then decreased. The quality and flavor were better preserved in the concentrated green as paragus juice with 30% soluble solid content.
