The occurrence of turbidity is a frequently observed phenomenon in beet sugar manufacturing, particularly in thick juice. The presence of small dispersed turbidity-causing particles can have a direct impact on the consumer’s perceivable quality of white sugar containing products. Therefore, this work aims to characterize those turbidity-causing particles and elucidate the mechanism of their formation. Samples from various European beet sugar plants were collected during different sugar production periods. The turbidity of white sugar is found to be mainly related to small calcium oxalate particles (0.45–1 µm). Their occurrence is obviously related to the presence of calcium and oxalate. However, the analysis presented documents that beyond the levels of these ions, other factors like storage time, the change of environment due to microbiological processes as well as simple processing steps have a profound effect on turbidity levels. The results confirm that also at an industrial scale calcium oxalate dihydrate precipitates from concentrated sucrose solutions despite the fact that calcium oxalate monohydrate is the most stable form. In summary our analysis of turbidity at an industrial scale marks a starting point for any further turbidity reduction approach.
The presence of practically non-dissolvable small particles in sugar solutions can cause haze during application and has to be minimal. Intermediate storage of thick sugar juice becomes increasingly common practice. In particular juices treated with anti-scale agents appear to be prone to turbidity development. This work on turbidity mitigation reports results on both laboratory and industrial level experiments. Different filter aids were tested and led to reduced turbidity levels. At industrial and lab scale reductions in the order of 30-54% and 50-70% were achieved respectively, which however remains insufficient to resolve the problem. The chemical mitigation by reduction of the hardness of the juice either by sodium carbonate or by ion exchanger treatment was investigated. While the reduction of the calcium concentration by dosing of sodium carbonate turned out to be basically possible, this remains less practical than the utilization of cation exchangers. Furthermore, it was found that application of anti-scale agents causes a reduction on the particle sizes that are found in thick juice samples after 2 months storage. Turbidity values of these samples were, independent of dosage and type of anti-scale agent, twice as high as in reference samples.
The pseudocereal amaranth is commonly used in food as whole puffed grain. To improve the utilization of amaranth, hydrothermally treated suspensions of puffed and raw Amaranthus caudatus flour and their blends were investigated in this study. The suspensions were hydrothermally treated at 20, 50, and 80°C for 1, 5, and 24 h. The blends were treated at 80°C for 1 h. The effect of hydrothermal treatments of the suspensions on their morphological (color, SEM), water‐binding, and rheological‐functional properties was studied. The puffed amaranth suspensions exhibited cold swelling properties by rapid viscosity increase and significant water absorption properties. It was found that hydrothermal treatment at 80°C for 1 h significantly increased water absorption and viscosity in puffed and raw flour suspensions. However, the puffed suspensions showed significantly higher values in water binding and viscosity. Suspensions of raw amaranth flour showed increasing color differences with increasing temperature. Blends of raw and puffed amaranth flour resulted in a decreasing color change with increasing puffed flour content. Water absorption of the samples increased with an increasing puffed flour content. Raw amaranth flour and the 50/50 (puffed/raw) blend had the lowest, 10/90 and 20/80 (puffed/raw), and showed similar viscosity profiles to suspensions of pure puffed flour.
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