Physical Chemical Characterization and Evaluation of Stability of Blackberry Juice Powder Produced by Spray Drying

Abstract

Many researches around the world have related the consumption of foods rich in phenolic compounds and the prevention of some diseases. The blackberry is a fruit with a large potential for industry application, due to its nutritional characteristics and the presence of phenolic compounds, mainly the anthocyanins with elevated antioxidant activity. However, the high perishability and the short post-harvest life of blackberry fruits limit their export for foreign markets and the utilization in food industries. Spray drying of fruit juices using carrier agents represents a viable alternative in order to improve the final product conservation, resulting in a powdered product with higher stability and shelf life, which facilitates the storage, handling and transportation operations. Furthermore, the carrier agents reduce powder higroscopicity and also can protect sensitive food components against unfavorable environmental conditions. In this context, the aim of this work is to obtain the powdered blackberry juice by spray drying process, using maltodextrina or gum Arabic as carrier agents. First of all, the effect of carrier agents concentration on the process yield, moisture content, higroscopicity, anthocyanins content and powder microstructure will be evaluated. Subsequently, the powdered juice samples, obtained from the conditions previously selected, will be characterized with respect to water activity, moisture content, apparent and true bulk density, porosity, solubility, color, total phenolic compounds, tannins, anthocyanins and antioxidant activity. The stability of particles exposed to different relative humidities will be also investigated through the construction of sorption isotherms. In the last step of this work, the shelf life study will be carried out, with the evaluation of microstructure changes, color, higroscopicity, antioxidant activity and anthocyanins stability of powdered blackberry juice throughout the storage time.