Search

Background: An interesting approach to improve dried foods nutritional properties, functionality, and sensorial attributes, is by taking advantage of pre-treatments for incorporating components into the food matrix. Based on this, this work studied the incorporation of black carrot anthocyanins in apple tissue by using ethanol (concentrations 0-300 mL L -1 ) as a pre-treatment to ultrasound-assisted convective drying. Samples were pre-treated in acidified ethanol solutions, with and without anthocyanins, and then dried (50 °C, 1 m s -1 ) by convective and ultrasound-assisted convective (21.77 kHz, 20.5 kW m -3 ) drying. Both the drying process improvement and the obtained product properties were studied., Results: The anthocyanins did not influence the drying kinetics. In contrast, time reduction was > 50% by using both ethanol pre-treatments and ultrasound. Ethanol pre-treatments decreased the external resistance to mass transfer, while ultrasound decreased both internal and external resistances. The impregnation increased the anthocyanins (above 947%), which were retained after drying. Colour modifications after pre-treatments and after drying (L*, b*, h° decrease, and a* increase), and antioxidant capacity retention were observed in samples with anthocyanin addition., Conclusion: The results point that ethanol pre-treatments and ultrasound application can accelerate drying, and through the natural colouring incorporation during pre-treatments, the nutritional properties of dried samples were better retained. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Ultrasound was combined with ethanol to improve different aspects of carrot convective drying, evaluating both processing and product quality. The ultrasound in water treatment resulted in cellular swelling and small impact on texture. Differently, the ultrasound in ethanol and ethanol treatments modified both carrot microstructure (cell wall modifications of parenchymatic tissue) and macrostructure (shrinkage and resistance to perforation). Pre-treatments with ultrasound in ethanol and ethanol improved the drying kinetics, reducing the processing time (~50%) and the energy consumption (42-62%). These pre-treatments also enhanced rehydration, whose initial rate and water retention were higher than the control. In addition, the carotenoid content was preserved after drying, for all the treatments. Any impact on shrinkage was observed. A mechanistic discussion, based on structural modification (microstructure and macrostructure) and physical properties of water and ethanol, was provided. As conclusion, this work not only described positive aspects of combining the technologies of ultrasound and ethanol as pre-treatments to convective drying, but also proposed mechanisms to explain the phenomena., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A revalorization of discarded carrots as substrate for the production of second-generation ethanol is proposed. In order to increase the fermentable sugar concentration of the musts two strategies were studied: Strategy 1 consisted in the enzymatic hydrolysis of bagasse must and Strategy 2 by which carrots were milled, dropped into distilled water and hydrolyzed with different enzymes prior to compressing and filtering to obtain carrot must. By applying Strategy 2 using 0.05% (v/v) of the enzyme Optimase CX255 at 70°C and pH 5.5 during 2.5h, the fermentable sugars extracted increased 3.5 times. In this way, the production of 77.5L of ethanol for each ton of discarded carrots was achieved. This process yielded bagasse as byproduct, which could be used for animal feed., (Copyright © 2012 Elsevier Ltd. All rights reserved.)