Dr. Bettina Schwarzinger works at the University of Applied Sciences Upper Austria in Wels, specialising in food technology and nutrition. She already has experience in the analysis of apple samples and was therefore an ideal partner for the AlpBioEco project and the apple value chain. Contact was established via AlpBioEco’s project partner Business Upper Austria and its Food Cluster in Linz (regional network of companies in the food industry from Upper Austria) and samples with apple pomace were delivered. Dr. Bettina Schwarzinger used various methods to examine them for their (possibly still usable) components. Here you can read about how the process developed and what results were obtained in the end.
AlpBioEco: Thank you for taking the time for an interview with AlpBioEco! Could you please shortly introduce yourself and your research focus?
I have been working at the Upper Austria University of Applied Sciences in Wels for four years and work specifically in the field of food technology and nutrition. I work in research and development, so I am not directly involved in teaching. However, we also supervise students with their bachelor or master theses. I am a chemist myself, I studied technical chemistry at the University of Linz and did my Ph. D. there.
AlpBioEco: How exactly did you collaborate with AlpBioEco?
The Food Cluster in Linz (Business Upper Austria) is one of the partners in the AlpBioEco project and is in constant contact with our professors. For example, during the Corona period, it was difficult for some of our students to do the internship because some companies no longer allowed external workers to work for them. For example, some students who actually already had an internship could not start it – but this is necessary in order to complete the bachelor's degree. One of our students who received a rejection was then referred to the Food Cluster at short notice. The analysis of apple pomace with the Food Cluster fit in very well with the topic, because that is an area in which I already had experience, that is, we didn't start from scratch either - you don't have much time for a bachelor's internship, as it usually consist of only ten or twelve weeks of practical work, and then the results are collated. I got the samples with apple pomace from Ms. Eder from the Food Cluster and then we started. The aim was to check the ingredients for their bioeconomic potential.
AlpBioEco: How did you continue? What were the results?
We examined various apple pomaces, i.e. the residues of apple juice pressing that came from four different farmers or companies. These were mixtures. They were not pure apple pressings – which was a bit of a shame, because maybe you could have made even more statements. But in reality, it was a matter of adapting various methods of assays for this problem and thus of seeing how many valuable substances are left behind. By valuable substances I mean, for example, residual sugar, various carbohydrates, proteins, or antioxidant substances such as polyphenols, which are dissolved in the juice and can be found in the residue.
In the end, we investigated how effective the squeezing out is – the more effectively the squeezing process, the less valuable materials remain. We have investigated which ions can still be found, which ash content remains, and which crude fibers (practically dietary fiber), pectins, proteins, sugars and organic acids remain. We also determined the water content, which plays a role, for example, when it comes to the shelf life of the apple pomace. We also looked at how much fiber is left that is not soluble – the more that is, the fewer valuable substances it contains. With other apple pomace, where the pressing was not so perfect, very interesting valuable substances such as proteins or pectins remained.
So we adapted the methods and applied them to the apple pomace, and then compared the four different samples – but making an absolute statement is always very difficult here. There is no such thing as one hundred percent extraction, or one hundred percent correct examination. However, one can say that we have found higher antioxidant capacities in a sample with more valuable substances, and not only with a photometric assay, but with various methods. Therefore, it has already been shown that there are trends.
And then you can still think about what to do with the apple pomace. Do you just feed it to animals? This is a more valuable contribution than you might think because it contains many antioxidants and proteins. But if you have a high sugar content, then that's not ideal for animals either. In addition, a small proportion of pectin and crude fibers makes the sample unusable for extraction. Or do you turn the apple pomace into a recyclable material? That is the aim of the AlpBioEco project, to continue using the residual materials in a bioeconomic manner and, for example, to produce biodegradable packaging from apple pomace. For this to happen, it would still have to contain many substances such as proteins or pectins, and if there is only little structural material, such as cellulose and so on, it will be impossible to obtain packaging material from it. One could also consider extracting pectin, which is also a commodity.
In order to make further statements about the best possible use, one would have to do further research, unfortunately ten weeks of research are not enough. For example, you would have to look at more samples from the same producer to find out how they vary within his processes. But there are for sure already very interesting approaches!
AlpBioEco: How does AlpBioEco's research project fit in with your other research?
For example, we have just completed and published a very long project with single-variety apple juices – it is always difficult to get single-variety samples. So, over several years samples of one apple variety have been collected over and over again, apple juice was pressed from them and then we made assays with the juice. As a result, we already had experience with organic acids, the determination of sugar in apple juice and so on. As part of our diabetes research, we often deal with this anyway, and then determine the sugar content with HPLC (high-performance liquid chromatography).
We also do the antioxidant assays constantly for a wide variety of tasks – of course you have to adapt this again and again. These aren't things that are difficult or complicated, much more difficult is the extraction, because the fabrics that we get are all solid. And the examinations take place in a liquid state. But how do I ensure that the solid substances turn into a liquid state? With extraction. And how do I do the extraction so that it takes place as thoroughly as possible? How often do I have to extract? We then simply tried out these things with apple pomace because we were interested, for example, in how often one had to extract so that nothing or very little remains.
And then investigated the extracts, for example concerning how much TPC (total phenol content) or which dry substances are still contained. At what temperature do I have to extract? At 50 or at 70 °C? Where do the substances start to break down again? Although they dissolve better at higher temperatures, they also begin to degrade again because they are broken down. In the AlpBioEco project, we tried to treat all four samples equally so that the four samples could be compared. Absolute values are always difficult, but you can compare the values quite well and then say, for example, that this sample is better suited for something than another.
AlpBioEco: What are your hopes for the future of food technology and bioeconomy in particular?
I wish that not more than needed is produced. I believe that most of our energy is wasted simply because we produce too much food and then throw it away. For this, we need energy twice – for the cultivation and for the production, but also for the destruction. I believe that you could solve a lot of problems around the world if you could get that under control.
We should use our resources better – having a lot of choice isn't necessarily a blessing. When I was little, there was one type of milk from a dairy in every district in Austria. Today there are 20 different types of milk, half of which will go past the expiry date and will be destroyed again. I would like that to come back into people's consciousness: a lot is not always good; a huge selection cannot work. With that we would not have a lot of problems anymore, such as the pesticide pollution, because it would no longer be necessary to generate such high yields. And food has to be valued monetarily again as well, as food is currently simply too cheap.
AlpBioEco: Thank you very much for the interview!
Dr. Bettina Schwarzinger collaborated within the AlpBioEco work package T1 analysing the bioeconomic potentials for the apple value chain. If you need more information about this collaboration and AlpBioEco work package T1, please read AlpBioEco Work package T1 report - results and replicable roadmap.
Photos: © Feichtinger & Schwarzinger