Aloe vera Cuticle: A Promising Organic Water-Retaining Agent for Agricultural Use

Abstract

Water is an important resource for both human and environmental survival. However, due to current human practices, we are facing a serious crisis in accessing water. Thus, solutions must be explored to optimize the use of this resource. In the search for an organic water-retaining agent for agricultural use, the techno-functional properties of Aloe vera (Aloe barbadensis Miller) cuticle, an agro-industrial residue generated after gel extraction, were evaluated. The residue was dried and ground. The effects of particle size (180 µm and 250 µm), temperature (10 °C, 20 °C, 30 °C, and 40 °C), and pH (4.5, 6.0, and 7.0) on the solubility and water-holding capacity (WHC) of the obtained product (i.e., hydrogel) were then evaluated. The treatment with the highest WHC was selected and compared with the WHC of a commercial synthetic polyacrylamide gel widely used in agriculture. The effects of KNO3 and Ca(NO3)2 at different concentrations (10 g L−1, 20 g L−1, 30 g L−1, and 40 g L−1) on the WHC of the gels were assessed. Particle size, temperature, and pH interactions had statistically significant effects on solubility, while the WHC was affected by particle size × temperature and pH × temperature interactions. The highest product solubility (75%) was obtained at the smallest particle size (i.e., 180 µm), pH 4.5, and 20 °C. Meanwhile, the highest WHC (18 g g−1) was obtained at the largest particle size (i.e., 250 µm), pH 6.0, and 20 °C. This optimized gel kept its WHC across both salts and their concentrations. In contrast, the commercial gel significantly decreased its WHC with salt concentration. The product elaborated with A. vera cuticle could have bioeconomic potential as a water-retention agent for agricultural use, with the advantage that it is not affected by the addition of salts used for plant fertilization.