Defining High and Low Spray Drying Temperatures for Aloe vera Gel

Abstract

Spray drying is widely used in the food industry to obtain products in the form of powder (Masters 1991; Filková and Mujumdar 1999; Nijdam and Langrish 2005; Roustapour et al. 2006; León et al. 2010). Three types of modes of contact between drying air and the food product can be found: parallel (co-current), counter-current, or mixed (fountain). The latter is a combination of parallel and counter current flow patterns, which implies that the already dry material comes into contact with drops being sprayed, favoring the formation of agglomerates. In turn, the formation of agglomerates raises the rehydration capacity of the final product (Masters 1991; Vega et al. 2001; Peighambardoust et al. 2011). Although spray drying is a common method used for drying thermolabile materials, there are few reports about the dehydrating conditions used for Aloe vera industrial processing. This plant is widely used in the pharmaceutical, cosmetological, and food areas because of the beneficial effects it provides as a functional ingredient in food and cosmetic products (Simal et al. 2000). However, it has been reported that when gel obtained from the Aloe vera leaf is subjected to thermal processing, changes in its components and functional properties, such as wettability, water retention, and oil adsorption capacity, among others, can occur (Eshun and He 2004; García et al. 2010). Aloe gel contains 98.5 % water, and the remaining solid material consists of polysaccharides, fat, and water-soluble vitamins, minerals, enzymes, phenolic compounds, and organic acids (Bozzi et al. 2007; Eshun and He 2004; Hamman 2008). Several studies have focused on assessing the physical, chemical and functional changes caused by Aloe vera gel processing conditions, especially during dehydration through convective drying (Simal et al. 2000; Femenia et al. 2003; Miranda et al. 2009; García et al. 2010; Gulia et al. 2010). However, to date there is limited data regarding the effect that spray drying temperature has on the physical, calorimetric, and functional characteristics of Aloe vera. Therefore, the objective of this study was to evaluate the effect of spray drying temperatures on obtaining Aloe vera gel in powder form.