Changes in Physico-Chemical Quality and Volatile Compounds of Orange-Carrot Juice Blends During storage

摘要

The present study aimed to determine the changes in physico-chemical parameters (pH, total soluble solids “TSS”, total acidity, vitamin C, total carotene, total phenolic and antioxidant activity) as well as sensory evaluation and volatile constituents of the orange juice samples mixed with carrot juice at ratios (1:3, 3:1 and 1:1). While, the polyphenol content was determined using Folin–Ciocalteu, antioxidant activity was measured using two in vitro assays 2,2'-diphenyl-1-picrylhydrazyl (DPPH 0 ) and metal chelating assays. While, the acidity increased, total carotene and pH of the juice decreased during the storage period. There were no significant changes in total phenolics throughout the storage period at the three blending ratios. A slight increase in antioxidant capacity during the storage period had been observed. The headspace volatiles of fresh orange and carrot juices as well as fresh and stored blend juice with ratio (1:3) for 14 days at refrigerator were collected and subjected to Gas chromatography (GC) and Gas chromatography-Mass spectrometery (GC-MS) analysis. A total of 26 volatile compounds were identified in samples of fresh orange and carrot juices as well as fresh and stored blend including 7 alcohols, 4 aldehydes, 9 monoterpene hydrocarbon and 6 esters. Limonene was the one most abundant monoterpene, representing in orange, carrot, fresh and stored blend 47.38, 42.37, 39.24 and 37.25%, respectively.