Effect of processing conditions (conventional heating, microwave, chilling, and freezing) on the stability of some bioactive compounds of jujube fruit

Abstract

The common processing techniques may cause losses in nutritional quality and phytochemical content of processed fruits. In the present research, the jujube fruit was processed by various methods including conventional heating (at 80 and 95 °C), microwave (600 W for 1 min), chilling (at 1 and 2 months), and freezing (at -18 °C for 1 year). Then, the effects of various common processing conditions were investigated separately on some bioactive compounds (e.g., total phenolic content, total monomeric anthocyanin content, individual anthocyanins, and individual organic acids) of jujube fruit. The microwave method in comparison with the conventional heating caused a slight significant (P < 0.05) decrease in the total monomeric anthocyanin and the total phenolic content (about 5.7% and 3.1%, respectively). The cyanidin-3,5-diglucoside was determined as the major anthocyanin in jujube fruit, while its degradation was more pronounced in the conventional heating at 80 °C (24.2%) compared to the microwave (2.7%), chilling for 2 months (20.1%), and freezing processes (8.4%). In general, malic, citric, succinic, and ascorbic acids were the most predominant organic acid in the jujube fruit. The ascorbic acid was one of the most sensitive organic acids of jujube fruit to processing methods. According to the results, the use of microwave energy and freezing treatment could be effective for the preservation of the natural organoleptic characteristics and bioactive compounds of jujube fruit.

Keywords

• Jujube fruit
• Processing methods
• Phytochemical content
• Nutritional quality
• Total phenolic
• Anthocyanin