Abstract
Guava (Psidium guajava L.) is one of the most nutritious fruits from tropical and subtropical regions; however, it is a seasonal and easily perishable fruit, besides not being produced worldwide. In this context, dehydration to produce powders simplifies product transportation and storage, however, the knowledge of bioactive compounds after drying is extremely important. Guava was dehydrated by a pilot scale cast-tape drying (CTD), a new low-cost dryer that allows the control of the spreading thickness, reducing significantly the drying time. Guava pulp was spread in CTD using 2 and 3 mm and dried at 98 °C to obtain powders with moisture contents of about 0.04 g/g (dry basis) and water activities close to 0.30. Powders obtained by CTD were compared to powders dried by freeze-drying (FD), and both drying processes, as well as guava pulp, showed high antioxidant activity and significant values of carotenoids and phenolic contents. Guava powders exhibited a wide range of particle sizes and flake-like structures, being easily dispersed in water, which indicates good rehydration properties of the products obtained from both drying methods. Therefore, CTD is a suitable process to produce guava powders with attractive properties, proving the preservation of important nutritional characteristics of the fruit.
Highlights
Guava (Psidium guajava L.) is a nutritious and appealing fruit from tropical and subtropical regions
Practical applications: This study investigated properties of guava powder obtained by Cast-tape drying (CTD), proving that the process promoted easy dispersion in water, a structure comparable to freeze dried powders and maintained significant values of nutrients
The moisture content of guava powder produced by cast-tape drying was 0.04 g/g, which depends on the drying time and the air conditions
Summary
Guava (Psidium guajava L.) is a nutritious and appealing fruit from tropical and subtropical regions. In the interest of increasing the usage and add value to guava fruit, drying to produce powder is an alternative to increase its shelf life and usage by industry, as a business-to-business product (Cuq et al, 2011; Nunes et al, 2016). The process consists in spreading the solution to be dried over a flexible film while its lower surface is in contact with hot water or steam, which provides the heat for the drying process An advantage of this method is the possibility of using moderate drying temperatures (60–80 °C) and relatively short times (some minutes) by selecting the appropriate thickness of the pulp layer to be dried (Zotarelli et al, 2017)
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