Color change of selected vegetables during convective air drying

Abstract

Color changes of potato, carrot and pumpkin during air drying were the subject of this study. Air convective drying was done at 70°C and 1.5 m/s. Color of the material undergoing drying was measured with chromameter and expressed in the CIE system with chromaticity coordinates x and y, and luminance Y. It has been found that drying affects color of investigated vegetables. Luminance increased and chromaticity coordinates moved toward whiteness until a specific water content was reached. Thereafter, luminance decreased and x and y coordinates moved toward the color of the raw material. It is suggested that changes of color of drying materials were due to removal of water, substitution of water by air and deformation of surface (shrinkage). At the end of drying a concentration effect seems to predominate. Rehydrated material had a different color than that of raw one. The difference was depended on the kind of material investigated and its reconstitution properties. Nevertheless the color changes irreversibly due to the changes of surface and internal structure of the material caused by drying and rehydration processes.     

The role of Lecane rotifers in activated sludge bulking control

Experiments were conducted on Lecane inermis feeding on filamentous bacteria and living in activated sludge to determine if the rotifers can control the growth of the bacteria responsible for bulking. The experiments showed that Lecane are capable of significantly reducing the density of Microthrix parvicella filaments. The rotifers not only survived the transfer from the culture to the activated sludge, but they multiplied quickly when foraging on filamentous bacteria. By reducing the number of filaments, the rotifers improved settling properties of the sludge. This is apparently the first report on the possibility of using rotifers to control bulking.     

Interaction of NO and NO2 with the surface of CexZr1−xO2 solid solutions – Influence of the phase composition

Structural (XRD) and spectroscopic (EPR, IR and Raman) investigations were performed to elucidate the influence of CeO₂ content on the phase composition and surface chemistry of Ce_xZr_1−xO₂ solid solutions (x = 0.10–0.85), interacting with NO and NO₂ in the absence and presence of oxygen. Strong influence of ceria loading on the adsorption modes of both nitrogen oxides and the nature of the resultant surface species was revealed. Adsorption of NO led to formation of mononitrosyl complexes, dimers and N₂O, whereas interaction of NO₂ with the ceria–zirconia catalyst resulted in the adsorbate disproportionation or coupling, depending on the sample composition.     

Numerical Procedure for Heat Transfer Coefficient Identification in Solidification of Binary Alloys and Its Experimental Verification

In this article the inverse problem consisting of determination of the heat transfer coefficient in the process of binary alloy solidification is considered. Additional information on the inverse problem is delivered by measurements of temperature at selected points of the cast. In the model discussed, the distribution of temperature is described by means of the heat conduction equation with the substitute thermal capacity, with the liquidus and solidus temperatures varying in dependence on the concentration of the alloy component. For describing the concentration, the Scheil model is used. For solving the direct problem, the finite-difference method supplemented by the generalized alternating phase truncation method is applied. For minimization of the properly constructed functional, the artificial bee colony algorithm is employed. Additionally, the article contains the results of a numerical experiment as well as the results of an experimental verification illustrating the usefulness of the proposed procedure.     

Suitability of unmalted quinoa for beer production

BACKGROUND

This study provides the first detailed investigation into the effect of partially substituting barley malt with quinoa (Chenopodium quinoa Willd.) on the characteristics of wort and beer. Quinoa seeds and flakes were compared in terms of their suitability for brewing. The benefits of applying a commercial enzyme mixture during beer production with quinoa were also investigated.

RESULTS

These findings show that quinoa is a good starchy raw material for brewing. Even without exogenous enzymes, it is possible to substitute barley malt with up to 30% quinoa. The form in which quinoa is used has a negligible influence on the quality of the wort and beer. The foam stability of beer made with quinoa was better than that of all‐malt beer, despite there being a lower level of soluble nitrogen in quinoa beer in comparison with all‐malt beer and more than twice the amount of fat in quinoa in comparison to barley malt.

CONCLUSION

The addition of unmalted quinoa does not give unpleasant characteristics to the beer and was even found to have a positive effect on its overall sensory quality. This offers brewers an opportunity to develop good beers with new sensory characteristics. © 2018 Society of Chemical Industry