Julianna Gyura

Separation of non-sucrose compounds from the syrup of sugar-beet processing by ultra- and nanofiltration using polymer membranes

Abstract Sugar, as the final product of the technology of sugar production, has to satisfy rigorous quality demands. Among others, it means low content of non-sucrose compounds, as well as the smallest possible share of coloured matters. Ultrafiltration and nanofiltration can be one of the solutions for a more effective separation of non-sucrose compounds from the intermediate products from which sucrose can directly be crystallized. Applying this procedure energy can be saved and the environment protected. Syrup solution from sugar-beet processing which contains 39.2% d.m. is being ultra- and nanofiltered.Polymer membranes with different MWCO (15–20 kDa, 6–8 kDa and 0.5 kDa) are used. Effects of UF are carried at 30°C and 60°C, with flow rates at 200 and 400 L/h and in the range of transmembrane pressure between 1–4 bar. NF is carried at 30°C and 50°C, with flow rates at 300 and 400 L/h and in the range of pressure between 1–30 bar. The separation of non-sucrose compounds is the most effective on a membrane with MWCO of 0.5 kDa, if the transmembrane pressure is kept at 30 bar and at a flow rate range between 300–400 L/h. Under these conditions colour and turbidity became lower for 76% and 80% respectively, if related to feed.

Survey on some contaminants in white sugar from Serbian sugar beet refineries.

Refined white sugar is a very pure food product, even though it contains very small amounts of soluble and insoluble impurities. The content of these impurities has nutritional significance and determines the usefulness of sugar for various industrial applications. The main quality criteria used to indicate the content of these impurities are ash and colour. The aim of this paper was to evaluate the quality according to the EU sugar market regime and the content of iron, copper and zinc in white sugar samples from Serbian sugar beet refineries during the 2003 campaign. A total of 166 samples representative of the production of four Serbian sugar refineries were investigated. After wet digestion the concentrations of iron, copper and zinc were determined by flame atomic absorption spectrometry. The mean content of iron, copper and zinc in sugar samples was 0.37 mg/kg, 0.06 mg/kg and 0.02 mg/kg and was significantly different from the average content 0.28 mg/kg, 0.09 mg/kg and 0.07 mg/kg respectively in the analysed European sugar factories. The data were also compared with literature values for commercial white sugar samples from European sugar beet refineries and European legislation set for copper and zinc. Furthermore, the quality of produced sugar was evaluated according to the standards of the European Union indicating that 76% of all investigated Serbian samples belonged to the second sugar quality category.

Flux Improvement during Cross-flow Microfiltration of Wheat Starch Suspension using Turbulence Promoter

The objective of this study was to investigate the effects of the process variables (transmembrane pressure, flow rate, and concentration) on the permeate flux during the microfiltration of model starch suspensions, and to determine the conditions under which the use of Kenics statics mixer as a turbulence promoter is justified. A response surface methodology was used to examine the influence of the selected operating conditions on starch suspension microfiltration using a single channel ceramic membrane with 200 nm pore size. The experimental results clearly show that the improved performance of starch suspension cross-flow microfiltration can be obtained by using a Kenics static mixer, especially at lower flow rates. Compared to the operation without the turbulence promoter, the average permeate flux improvement during the filtration period ranged from 30% to 230%. As a result of the statistical analysis, the optimal conditions for starch suspension microfiltration were determined and applied to microfiltration of starch industry wastewater.

Influence of low‐melting milk fat fraction on crystallization and physical properties of chocolate

Purpose – Investigated milk fat fraction differs in physical attributes, first of all in melting point and solid fat content and its influence on crystallization process of cocoa butter i.e. chocolate mass. It means that this fraction slows down crystallization rate, decreases melting point of mixture with cocoa butter and causes chocolate softness. It is very important for quality of chocolate especially chocolate with nuts or sunflower kernel. The aim of this paper was to investigate the influence of low‐melting (26°C) milk fat fraction on crystallization processes in chocolate mass and define the optimal concentration of this fraction with suitable precrystallization temperature time regime. Solid fat content of chocolate which designates the influence of precrystallization changes in chocolate mass with addition of milk fat fractions was investigated.Design/methodology/approach – The precrystallization was performed in a laboratory crystallizer that is in a modified Brabender pharinograph, which measu...

The Application of Membrane Separation Processes as Environmental Friendly Methods in the Beet Sugar Production

The sugar industry is one of the key segments of the food industry. This industry is also well known as one of the most energy-intensive in the field of food and chemical industry. In 1999, the total quantity of produced sugar was summarized. It was reported that the production reached 16 700 000 tones, while the total value of the produced sugar was 8924 million EUR. A significant quantity of thermal energy was consumed for the evaporation and beet pulp drying, as well as electrical energy needed for the pumps and for driving the centrifuges. According to CEFS, specific energy consumption was 31.49 kWh/100 kg beet in 1998 (IPPC, 2003). In a Greek study, a figure of 280 kWh/t is given for the electrical part of the energy consumption in sugar manufacturing (IPPC, 2003). While the overall water used is about 15 m3/t sugar beet processed, the consumption of fresh water is 0.25 – 0.4 m3/t sugar beet processed, or even less in modern sugar factories. Water consumption depends on the activities of each installation, e.g. more water is consumed in an installation that extracts and refines sugar beet compared to the one that does only one of these activities (IPPC, 2003). For example, the consumption of water in Austria was reported at a level of 1.5 m3/t of sugar beet processed, which is equivalent to 9 m3/t of produced sugar (IPPC, 2003). The transport water has high organic contamination due to the soil and sugar from damaged beets. Its COD is 5000 – 20000 mg/L. Waste water with high BOD levels is produced in large volumes (IPPC, 2003). Despite the fact that the sugar industry is one of the causes of the environmental pollution, not enough has been done on its improvement. The technology applied in almost all European sugar factories is based on the traditional principles and methods. The major steps in the traditional sugar beet processing are (Poel Van der et al., 1998): i) Pre treatment – Washing and slicing of the sugar-beets into cosettes are the initial operations;