Berlin Symposium on Sugar Technology

On 31st of March, the first Berlin Symposium on Sugar Technology took place. The Department of Food Process Engineering, which is the successor to the Berlin Sugar Institute, was the main organizer. The department joined forces with Verlag Bartens to organize the meeting which had been discussed some time ago between the Department and the “Sugar Industry Foundation” – which supports the activities of Department. But the Covid pandemic delayed it.

The meeting’s goals reflect the one organized by the Department of Food Process Engineering in 2022 – that is to create a forum for pre-competitive discussions on technology. Ideally, this meeting should bring industry and academia together so that new ideas to overcome today’s problems but particularly those of the day after tomorrow can be developed by bringing people from different fields together. It is thus about combining industrial long-term wants with academic open-mindedness. Or in other words, it should invite new insights.

On the evening preceding the symposium about 30 participants met in a Berlin restaurant to refresh friendships and to discuss common points of interest, not just on sugar technology, but in general. This social event set the friendly and open atmosphere for the meeting the next day.

The program comprised four industrial and five academic contributions – a nearly equal balance between industry and academia. We had hoped to receive more contributions from sugar producers. To what extent this is actually a drawback of the meeting remains an open question. Possibly a clearer and more up-front communication inviting the stakeholders from the industry to highlight issues that are impacting their business now and in the foreseeable future and which they feel should be on the agenda could help to change this in the future. After all it should be of general interest that the pre-competitive, primarily academic, work remains relevant. This necessitates that at least the long-term obstacles and relevant questions are discussed in the community.

The meeting took place in the main building of the Technische Universität Berlin. Prof. Eckhard Flöter opened the session with an introductory overview on the day’s proceedings. About 40 participants were present. The lecture theater probably reminded some on their student days.

Purification of sucrose and non-sucrose solutions

Dr. Nadja Hermsdorf (Lanxess) presented the first paper – on the application of ion exchangers. In the talk entitled ‘Purification of sucrose and non-sucrose sugar solutions with Lewatit® ion exchange resins (IXR)’, she discussed the collection and relevance of data in the laboratory to design processes and for the calculation of operating costs of e.g., Lewatit® ion exchange systems for purification of sugar and non-sugar solutions. She indicated how these data can be used to design and optimize ion exchange resin applications in general and for the consumption of chemicals and water. Furthermore, the function of resins in both ion exchange and adsorber mode were discussed. Finally, the now openly accessible calculation tool LewaPlus® Food module was presented. It allows the evaluation of different process configurations and their respective costs.

The next presentation concerned the area of non-sucrose sugars. The use of ion exchange resins is a highly relevant for purification. The paper ‘Physical and chemical properties of non-sucrose sugars and challenges during crystallization’ by Prof. Dr. Eckhard Flöter and Dr. Karl Schlumbach (both TU Berlin) first introduced the area of non-sucrose sugars with emphasis on the thermodynamics underlying crystallization. The effect of the possible formation of hydrates was exemplified in the trehalose water system. Different downstream processing options were discussed based on data cited in literature and their own practical experience. Final remarks on the consequences of inappropriately applying established analytical methods completed the talk.

Evaluation of massecuite quality

In the presentation by Barbara Muir (Tereos) that followed, she illustrated with verve that substantial improvements in energy consumption, pan operation and sugar quality can be realized within the established framework. The power of the tools developed by Tereos R&D for the evaluation of massecuite during and at the end of a crystallization strike was highlighted with reference to case studies from different factories. It was shown that good data acquisition, targeted experimentation, and a good understanding of science and technology can deliver significant benefits.

Sucrose solubility in cane sugar solutions

Maximilian Goehler from Alpina Orion and Centro Universitario FEI in Brazil presented his paper ‘Research on the sucrose solubility in technical (impure) sugar cane solutions’ via videolink. The work described sucrose solubilities in cane sugar molasses. Adhering to the same framework as recently revisited by J. Tuchert in his PhD thesis, solubility data gathered by execution of the Polish test were described by the Vavrinecz equation.

The work suggests that the beet-based framework to quantify supersaturation better and determine seeding points can be transferred to cane processing insofar as the set of non-sugar compositions still need to be enlarged in further studies with molasses from different sugar factories and different crop moments.

Juice concentration by membranes

Unfortunately Prof. Dr. Michael Harasek (Technische Universität Wien) was not present in person due to Covid complaint, but he was able to deliver his presentation on the application of membranes to concentrate thin sucrose juices online. Along with the general discussion on membranes, the ingenious process scheme to combine reverse osmosis and other membrane modules was presented. Central to this solution developed at the TU Wien is reducing the osmotic pressure in modules dealing with thick juice. This is achieved by controlled sucrose leakage into the membrane’s permeate side. In doing so, the trans-membrane pressures are controlled so that processes can be economically designed. However, up to now, the implementation in sugar factories has remained unlikely because of the abundant availability of steam in sugar factories. With the ongoing rapid changes concerning energy consumption and climate relevant emissions, however, this situation could soon change.

Modelling of evaporation rates in sucrose crystallizers

In another contribution from TU Berlin, Felix Geisendörfer discussed the ‘Numerical modelling of evaporation rates in sucrose crystallizers’. In this presentation, the earlier formulated hypothesis that sucrose crystals play a role in the nucleation of steam bubbles took center stage. Felix Geisendörfer developed a model that calculates the steam generation during a strike. Key elements of the model are bubble nucleation in both the calandria and at crystal surfaces, vertical temperature profiles, and the bubble point temperatures as a function of hydrostatic pressures. When applying the model in purely predictive mode, the experimental reference data gathered at the industrial scale are represented qualitatively. The agreement improves dramatically with good adaptions of heat transfer coefficients and vertical flow rates in the calandria. The most prominent outcome of the simulation is the representation of the observation made in practice that steam bubbles during the strike are only detectable well above the calandria. This, while matching the industrial data for the generation of steam.

Effect of dextran on color inclusion

In the final set of talks, Dr. Karl Schlumbach (TU Berlin) reported on ‘The effect of Dextran on color inclusion’. Dextran has notably gained much attention in the past campaign due to inclement weather. The main dextran-related problems are notably seen much earlier in the process. Nonetheless, it is important to understand that dextran also has negative effects during crystallization. The thorough analysis revealed that increased color values induced by dextran are due to color inclusion and not adhering to syrup. Additionally, the work showed that when dextran is degraded by dextranase application to solve other processing problems, the enhanced color inclusion phenomenon can be suppressed.

Mid-Range IR Spectroscopy for determination of sugars

That spectroscopic analysis can generate value within the sugar technology is undisputed. In the paper by Dr. Daniel Sellin (IRPC Infrared – Process Control GmbH) on ‘Benefits of Compact Mid-Range IR Spectroscopy for determination of primary sugars’ a practical application was discussed. It was shown that compact midrange analytical equipment can also be used outside specialized analytical labs, hence industrial applicability. In particular, data on determining the respective concentrations of sucrose, fructose and glucose in molasses were presented. The results regarding this challenging task are promising, but the conclusion on universal applicability in varying molasses compositions remains subject to debate.

Photon Density Wave spectroscopy for monitoring crystallization

Dr. Anne Hartwig (University of Potsdam) concluded the meeting with a presentation on the ‘Photon Density Wave spectroscopy for monitoring sucrose crystallization’ was given. This analytical method combines multiple optical fibers in the probe head to allow simultaneous monitoring of absorption and scattering. The fact that the reduced scattering coefficient depends on the size and number of scattering particles makes it interesting to monitor sucrose crystallization. This is mainly because the technique is suited for highly concentrated liquid dispersions and robust against fouling. Initial attempts to monitor the crystallization of sucrose were impeded by insufficient process control. Findings from discussions on application tests at the symposium will be performed at the TU Berlin.

The presentations were clustered into blocks and the coffee and lunch breaks were not only used to consume drinks and food but also gave ample space for intense discussions. Summing up the feedback gathered accidentally, one could write ’good program’, ‘a Friday well spent’; ‘a program that had deserved a larger audience’, ‘glad I came’. My own summary – new methods, new tools, new insights, controversial discussions – mission accomplished. See you in 2025 in Berlin. (Eckhard Flöter)

Keywords: Symposium