Andrea Hinkova

Potentials of separation membranes in the sugar industry

There are described some applications of membrane separation, e.g. reverse osmosis in the treatment of sugar beat press water, recovery of salt from waste brine at a sugar decolorization plant or microfiltration and ultrafiltration of raw sugar juice, as an alternative to chemical purification process. The last case is completed by original experimental work. Samples were treated with cross flow micro- and ultrafiltration on ceramic membranes having porosity 20 and 50 nm. The changes in the content of sucrose, invert sugar and lactic acid were observed, resulting in increasing the juice purity from the initial value 89% to the final value 91‐92%. In addition, permeate can be a subject for direct crystallisation after thickening to produce the final product. Retentate purity decreased to 87‐88%. For nanofiltration tests (NF) there has been designed a special stainless steel cross-flow dynamic cell for pressures up to 4 MPa. The preliminary NF tests were focused on testing different commercial flat polymeric membranes (Hydronautics-Nitto Denko, Osmonics-Desal).

Application of continuous chromatographic separation in sugar processing

Abstract The work deals with application of continuous counter-current chromatographic separation station in sugar technology. There are two main targets in this study: (1) Changes in sugar technology: simplification of sugar processing by sucrose crystallization from chromatographic extract without any previous demanding chemical processing and (2) higher valorisation of waste material and intermediates from sugar processing by isolation of high-quality substances. The chromatographic pilot plant KCHS-SMB-8, which was developed by the Department of Carbohydrate Chemistry and Technology ICT Prague and the firm MIKROPUR Hradec Kralove, was used for this purpose. Experiments deal with suggestion and verification of main operation conditions during chromatographic separation of technical sugar solution. The process was focused on separation of various model mixtures of sucrose/salt and sucrose/betaine. Results provide a basic data for further research and development for industrial use.

Processing of yellow pea by germination, microwave treatment and drying

A high content of α-galactooligosaccharides affects the nutritive value of legumes. In agreement with papers concerning the effect of germination on the composition of various grain legumes, our results show that the most important decrease of α-galactooligosaccharides (raffinose family oligosaccharides — RFO) in the yellow pea (Pisum sativum) occurs during the first 3 days of germination. Wet germinated peas were treated by microwave (MW) energy and dried by hot air at 80°C. The benefit of MW treatment is shortening and improvement of drying. Proposed processing steps for the modification of nutritional properties of pea include: (1) germination of pea seeds (3 days); (2) MW treatment of germinated seeds; (3) drying by hot air; (4) grinding of dried seeds; and (5) preparation of meal from the modified pea flour.

Cheese whey tangential filtration using tubular mineral membranes

Membrane separation techniques are extensively used in dairy industry both for milk and cheese whey processing. However, cheese whey might still be considered as a problematic waste despite its high content of many valuable substances, such as proteins, lactose or minerals, which can be further used, e.g. in human nutrition, pharmacy or biotechnologies. Another problem, which food technologists have to face, is variable quality, composition and properties of food materials bringing high demands on manufacturing industry. In this paper, filtration kinetics and separation efficiency during purification and fractionation of cheese whey (sweet and salty) from Czech dairies by pilot-plant filtration (Bollene, France) was studied using tubular membranes (Membralox, USA). Various mineral membranes’ cut-offs were tested and all experiments ran in the retentate recycling mode. The obtained mass concentration factors were between 1.9 and 16.5. Steady state fluxes were calculated from the experimental data using a mathematical model. Fine ultrafiltration on a 5 kDa membrane gave steady state fluxes of 14–19 L m−2 h−1. The coarse pre-filtration on 100 nm, 200 nm or 500 nm membranes showed various permeate fluxes between 22 L m−2 h−1 and 153 L m−2 h−1. Despite the high pore sizes of the used membranes, lactose was partially rejected by all membranes tested.