The agave fructans as carrier agent can be an alternative to increase quality properties of blackberry. The aim of this study was to evaluate the effect of agave fructans concentration and inlet air temperature on quality properties of blackberry powder. Agave fructans concentrations were 50, 75 and 100 % (in base the total soluble solids percentage of blackberry extract), and the inlet air temperatures were 70-110°C. A pilot-scale spray dryer was employed. Drying yield ranged from 58 to 94 % dry base. Encapsulation efficiency values varied between 48 and 100 % of anthocyanin concentration. The lower agave fructans concentration showed the best quality characteristics as lower water activity of 0.28, high anthocyanin retention of 98 %, high bulk density of 0.80 g/ml and the higher agave fructans concentrations showed the best stability properties as lower hygroscopicity of 0.013 g H20 /g solids and low particle temperature of 38°C. The agave fructans improves good physicochemical and stability characteristics in blackberry powders.

The objective of this investigation was to evaluate the influence of two carrier agents, Nopal and Aloe Vera mucilage on the physicochemical properties and stability of blackberry and raspberry powders obtained by spray drying. A pilot scale spray dryer with a feed flow of 20 L/h and an atomization speed of 28,000 rpm was used. The inlet and outlet air temperatures were from 180 to 80°C, respectively. Yield, moisture content, water activity, hygroscopicity index, solubility time, volumetric density, stability diagrams, micrographs, and particle temperature were evaluated. The highest yields for blackberry extract were 75% with a concentration of 2.5% (w/v) Nopal mucilage, while raspberry extract yielded 65% with a concentration of 5% (w/v) Nopal mucilage. The increase in the concentration of the carrier agent presented an increase in the values of humidity, water activity, volumetric density, and solubility when Nopal mucilage was used as a carrier agent in both blackberry and raspberry extracts. Furthermore, when Aloe Vera mucilage was used as a carrier agent, these same values decreased with increasing concentration. The storage conditions of the powders obtained should be stored at temperatures below 20°C and water activities below 0.4. In addition, the stability diagrams show the particle conditions that should not be exceeded during spray drying.

Solar collectors are thermal devices that can trap solar energy and convert it to heat. This heat can be used for different industrial applications, for example, the drying of food is one of the most useful applications of solar collectors. This work aims to design and build a solar collector using nanofluids for the convective drying of food. The dimensions of the solar collector were 1 m2 by 20 cm with an angle of inclination of 45°. The collector was composed of 9-mm thick tempered glass and a heat exchanger in which the nanofluids circulate. Nanofluids were designed based on canola oil and nanopowders (>50 nm) of Al2O3, CuO, and a 1:1 (w/w) mixture of both. Thermal profiles were determined using differential scanning calorimetry (DSC). The solar collector temperatures were recorded using an Agricos® unit. The maximum temperatures of the air leaving the collector were 39.1°C, 44°C, 54°C, and 47.1°C for canola oil, and the nanofluids composed of Al2O3, CuO, and the 1:1 mixture, respectively, with a maximum efficiency of 65.09%. An increase in the outlet air temperature was observed using the nanofluids compared to canola oil alone