Effect of Modified Solar Dryers on Colorimetric and Physicochemical Properties of Pumpkin Flower (Cucurbita maxima).

This study aimed to evaluate the solar dryers' cover material effects on the colorimetric and physicochemical properties of pumpkin flowers (Cucurbita maxima). A direct cabinet solar dryer was designed using three cover types: polycarbonate, polyethylene, and aluminum with selective surface (titanium oxide coating). A unifactorial experimental design with three levels was adopted. Pumpkin flower stability was assured by reducing the initial moisture content (95.22%) and water activity (0.989) to 3.15% and 0.276 in the polycarbonate dryer, to 3.03% and 0.279 in the selective surface dryer, and 5.19% and 0.364 in the polyethylene dryer. The drying kinetics showed that the drying time needed to achieve the moisture equilibrium was 480, 540, and 720 min in the respective dryers, depending on the ambient conditions. The initial pumpkin flower hue angle was 76.52°; however, this value decreased to 74.81, 69.52, and 70.23° in the dryers with polycarbonate, polyethylene, and the selective surface respectively; this behavior indicates a pumpkin flower tendency to orange color. The dryer with the selective surface obtained the best properties in pumpkin flowers. The pumpkin flower showed an initial total soluble solid of 1.5°Brix increased to 30°Brix in the polycarbonate and polyethylene dryers and 39°Brix in the selective dryer. The titanium oxide dryer observed an increment in ascorbic acid content from 3.5 to 8.806 mg/100 g, whereas 6.45 and 5.87 mg/100 g in the polycarbonate and polyethylene dryer, respectively.

Saccharomyces cerevisiae mixed culture of blackberry (Rubus ulmifolius L.) juice: synergism in the aroma compounds production.

Blackberry (Rubus sp.) juice was fermented using four different strains of Saccharomyces cerevisiae (Vitilevure-CM4457, Enoferm-T306, ICV-K1, and Greroche Rhona-L3574) recognized because of their use in the wine industry. A medium alcoholic graduation spirit (<6°GL) with potential to be produced at an industrial scale was obtained. Alcoholic fermentations were performed at 28°C, 200 rpm, and noncontrolled pH. The synergistic effect on the aromatic compounds production during fermentation in mixed culture was compared with those obtained by monoculture and physic mixture of spirits produced in monoculture. The aromatic composition was determined by HS-SPME-GC. The differences in aromatic profile principally rely on the proportions in aromatic compounds and not on the number of those compounds. The multivariance analysis, principal component analysis (PCA), and factorial discriminant analysis (DFA) permit to demonstrate the synergism between the strains.