Improvement of the phenolic composition and the antioxidant capacity of red guava (Psidium guajava) and watermelon (Citrullus lanatus) powders by means of foam blanket drying

Abstract

Red guava and watermelon have good sensory and nutritional attributes. However, they are highly perishable. Aiming to improve this condition, drying is presented as a technique that promotes the reduction of water content, extending the useful life of products. The elaboration of guava and watermelon powders by drying in a foam blanket with optimization of the proportion of the foaming agent (powdered albumin) and agitation time (10′) were studied, and the influence of the drying method on the physicochemical quality, phenolic composition and antioxidant capacity of the material. Density, stability and% expansion was evaluated and the optimal condition for foam formation was: 5 and 15% (w/w) of additive for guava and watermelon, respectively. The foam was dried at 68 °C. The physicochemical properties of the powders showed that the technique is a viable alternative in obtaining a by-product that is easy to reconstitute. All powders showed an increase in phenolic content that potentially contributed to a greater antioxidant capacity after the drying process in all tests performed. This result reveals the drying potential for the production of fruit powders, adding value to these raw materials, promoting the potential for application in the manufacture of good quality by-products.

Keywords

• Red guava
• Watermelon
• Drying on a foam mat
• Antioxidant
• Phenolics
• Stability