Aloe vera plant is known worldwide for its medicinal properties and application in gel-based products such as shampoo, soap, and sunscreen. However, the demand for these gel-based products has led to a surplus production of Aloe vera processing waste. An Aloe vera gel processing facility could generate up to 4000 kg of Aloe vera waste per month. Currently the Aloe vera waste is being disposed to the landfill or used as fertilizer. A sustainable management system for the Aloe vera processing waste should be considered, due to the negative societal and environmental impacts of the currents waste disposal methods. Therefore, this review focuses on various approaches that can be used to valorize Aloe vera waste into value-added products, such as animal and aquaculture feeds, biosorbents, biofuel and natural polymers. Researchers have reported Aloe vera waste for environmental applications biosorbents used for wastewater treatment of various pollutants. Several studies have also reported on the valorization of Aloe vera waste for production of biofuels such as bioethanol, mixed alcohol fuels, biogas and syngas. Aloe vera waste could also be valorized through isolation and synthesis of natural polymers for application in wound dressing, tissue engineering and drug delivery systems. Aloe vera waste valorization was also reviewed through extraction of value-added bioactive compounds such as aloe-emodin, aloin and aloeresin. These value-added bioactive compounds have various applications in the cosmetics (non-steroidal anti-inflammatory, tyrosinase inhibitors) and pharmaceutical (anticancer agent and COVID 19 inhibitors) industry.

Valorization of Aloe barbadensis Miller. (Aloe vera) Processing Waste

Aloe barbadensis (Aloe vera) has long been used in food, cosmetic and pharmaceutical industries. In order to maximally extract soluble sugars, different drying methods, such as heat-drying (HD), air-drying (AD), vacuum freeze drying (VFD), and microwave drying (MD), on the sugar content were investigated in the present work. Besides, the relationship between the particle size and the physicochemical property of the peel powder obtained by ultramicro-pulverization was also explored. The results showed that different drying method did have significant effect on the soluble sugar content. HD, AD, and VFD possessed similar sugar content (approximately 8.27, 8.46, and 8.46 g/100g, respectively). The highest sugar content was found in MD (9.36 ± 0.30 g/100g), indicating that MD was the most effective way to extract sugars from Aloe vera peel among these four methods. The particle size of the peel power after dried by MD was affected by the crusher time and power. The higher the power, and the longer crusher time, the smaller particle size of the powder. Along with the decreasing of particle size, the color parameter (B value) of the peel powder significantly decreased from 24.47 to 16.90 (P < 0.05). The water holding capacity also decreased when the D (0.5) reduced due to the lower binding capacity of small size particle towards water. As the reduction of D (0.5) value, the water holding capacity decreased (from 6.21% to 3.52%). The present work could provide valuable information for the comprehensive utilization of the by-products of Aloe vera.

L K Ma

Papers

Effect of particle size on the physicochemical property of the peel powder from Aloe barbadensis