Contrary to the definition, “Dietary fiber contains lignin, which is not metabolized by mammalian animals”, we have our doubts according to our recent results.

The possible metabolic reactions of the aromatic biopolymer lignin were investigated as a part of the GOOD-project: Improved gut health by wood-derived gums (Jane and Aatos Erkko Foundation). In the experimental setup of the project, rats consumed hemicelluloses (mainly xylan) derived from birch wood in their diet. In the first part of the project, it was found that xylan has potential as a prebiotic dietary fiber promoting gut health.

Reference to the first part of the study on xylan promoting gut health:

Kynkäänniemi, E., Lahtinen, M. H., Jian, C., Salonen, A., Hatanpää, T., Mikkonen, K. S., & Pajari, A. M. (2022). Gut microbiota can utilize prebiotic birch glucuronoxylan in production of short-chain fatty acids in rats. Food & Function, 13(6), 3746-3759.

In the experimental setup the xylan groups were further divided into two different groups: one group obtained purified xylan, whereas the other group also obtained lignin, which is present in the unpurified xylan. By using many modern analytical tools in chemistry and gut microbiome research, we gained multiple pieces of evidence showing that lignin is metabolized by the action of certain gut microbes from the Eggerthella genus in the large intestine to smaller molecules, such as sinapic and ferulic acids, and their derivatives. The collaboration in our multidisciplinary research team was integral and many of the tools used came from the field wood chemistry. In addition, knowledge in food and nutrition, and gut microbiome research were essential in order to gather, interpret, and make conclusions of all the findings.

Reference to the second part of the study on lignin metabolism:

Lahtinen, M. H., Kynkäänniemi, E., Jian, C., Salonen, A., Pajari, A.-M., Mikkonen, K. S., Metabolic fate of lignin in birch glucuronoxylan extracts as dietary fiber studied in a rat model. Mol. Nutr. Food Res. 2023, 2300201.

Exploring Helsinki: Our Thrilling City Adventure

The Food Materials Science Research Group embarked on a refreshing summer recreational event. Turning the bustling streets of Helsinki into our playground, we delved into an exciting Foxtrail city adventure.

Under the sunny sky, we collected at Rautatientori on May 29, 2023, at 2 pm, brimming with enthusiasm for our urban quest. We split into four teams. Two teams took on the challenge of Route Sampo, where modernity meets history, while the other two teams chose Route Louhi, where the bustling city meets tranquility. Equipped with the instructions, we were prepared for the adventure ahead.

As we followed the trail, we discovered a different side of Helsinki. From modern and historical buildings to green parks and beautiful shores, each clue led us deeper into the heart of the city. We were amazed by the vibrant tulips blooming at the entrance of an ancient castle and a magnificent sailing ship gracing the port. The excitement grew with each puzzle we solved, and the satisfaction of unraveling each clue motivated us to keep going.

Of course, the trail had its challenges. Some clues puzzled us, while others took us on unexpected detours. With some luck, the fastest team reached the destination in just two hours, stumbling upon the correct path without finding all the clues. However, not all teams were as fortunate. One team struggled briefly with a clue and almost boarded a ship bound for Suomenlinna, a distant island location. But we persisted and overcame each obstacle.

Afterwards, we enjoyed a reinvigorating and delightful meal. The thrill of reaching milestones, combined with the breathtaking views, made the journey truly worthwhile.

Our city adventure in Helsinki was an unforgettable experience. It revealed the city’s hidden treasures and left us with lasting memories. Additionally, it brought us closer as a group. In moments of puzzlement, we gathered together, shared ideas, and contemplated the intricate clues. Some riddles tested our patience and challenged our collective intelligence, but we approached the journey as a team, celebrating each breakthrough. This collaborative spirit mirrored our approach to research problems, strengthening our bonds and creating unforgettable memories.

FinPowder: Wood hemicelluloses are effective wall materials for spray dried microencapsulation of bioactive compounds from bilberry with improved functional properties of produced microcapsules

Two years have passed since Abedalghani Halahlah (Abed) who is working as a doctoral researcher commenced in the FinPowder project (here) at the University of Helsinki (Abed, Figures a and b).  We are now back to deliver more interesting findings/outcomes to add to the previously revealed results (here) that have already been published as two impactful articles.

First article: Abedalghani Halahlah, Vieno Piironen, Kirsi S. Mikkonen, and Thao M. Ho. “Wood Hemicelluloses as Innovative Wall Materials for Spray-Dried Microencapsulation of Berry Juice: Part 1—Effect of Homogenization Techniques on their Feed Solution Properties.” Food and Bioprocess Technology 16, no. 4 (2023): 909-929.

Second article: Abedalghani Halahlah, Heikki Räikkönen, Vieno Piironen, Fabio Valoppi, Kirsi S. Mikkonen, and Thao M. Ho. “Wood hemicelluloses as sustainable wall materials to protect bioactive compounds during spray drying of bilberries.” Powder Technology 415 (2023): 118148.

In the first article we revealed that, magnetic stirring is the best choice for preparing wood hemicellulose (glucuronoxylans and galactoglucomannans) feed solutions for the spray-dried microencapsulation of bilberry juice. This is because microfluidization caused a loss of total anthocyanin content of the feed solutions. Furthermore, galactoglucomannans feed solutions formed a gel-like structure within a short time after ultrasonication and microfluidization, making these solutions unsuitable for spray-drying. Here also, we reported, for the first time, the formation of gel-like structures from a pressurized hot water extraction galactoglucomannans solution which was further investigated in a separate study (here). While in the second article, we demonstrated that wood-based hemicelluloses are efficient wall materials for the spray-dried microencapsulation of bilberry juice. The encapsulation efficiency values of wood-based hemicelluloses were relatively high and close to that of gum arabic (∼ 73%). Due to the natural presence of lignin-derived phenolic compounds in the structure of wood-based hemicelluloses, their microencapsulate powders had significantly higher phenolic content and antioxidant activities than gum arabic powders.

The findings of these two studies provide another value-added application of wood hemicelluloses obtained from waste and by products of the forest industry. Wood hemicelluloses can replace the currently used wall materials in the production of high-quality bilberry powders via a more cost-effective method (i.e., spray drying) than those currently used (freeze drying and freezing), thus offering an economic opportunity to bring bilberry products to global consumers. Alongside these financial gains, wood hemicelluloses also bring health benefits by adding dietary fibres and antioxidant functionality to the final products.

The experimental work was continued by further advancing the functional properties of produced microcapsules, for example by optimizing the ability of wood hemicelluloses to retain and protect bioactive compounds during spraying. In this regard, we carefully planned two models/approaches of experiments to obtain the best bioactive compounds retention and functional properties of the produced microcapsules. The first approach involved the use of carboxymethyl cellulose as a co-wall material combined with wood hemicelluloses to produce the microcapsules at fixed spray drying conditions. During this stage, we also used an advanced analytical technique (computed X-ray microtomography) in collaboration with Department of Chemistry at University of Helsinki to reveal interesting information regarding the internal and external structure and thickness of coating layer of the microcapsules (Figure-c) In the second approach we used wood hemicelluloses alone as wall materials but aimed to find the best processing conditions including inlet and outlet temperatures and the ratio between wood hemicellulose and bioactive compounds (Figure-d). The optimal microcapsules were further analyzed for their phenolic compounds profile including anthocyanins by Ultra-High-Performance Liquid Chromatography (Figure-e).

Luckily, we were able to improve the retention of the bioactive compounds in both approaches with very interesting observations and results that are currently under preparation for publication. The results provide valuable steps towards production of food powders and functional ingredients with high added nutritional values and functional properties with minimal cost.

The FinPowder project has received a third year of funding from the Finnish Natural Resources Research Foundation to conduct further investigations on microcapsule stability and digestibility. In the near future, the optimal microcapsules of wood hemicellulose will be studied for their storage stability over 6 months and in vitro digestion. More to come!

Figure: (a) Abed next to the Liquid Chromatography instrument and (b) conducting spray drying experiments (c) X-ray microtomography images exhibiting the internal and external structure, wall thickness and diameter, (d) The effect of spray drying conditions on the encapsulation efficiency, illustrated as three-dimensional plots and (e) Chromatogram shows 9 peaks of different anthocyanins compounds were found in the microcapsules.

iOLEO state of play: a synchrotron study of lipid carriers

Last December, four FoMSci group members travelled to Italy to work in the Elettra Sincrotrone Trieste facilities. This experiment is a part of the iOLEO project (three-year research grant), which aims to develop novel oleogels with tailorable digestibility, unlocking the potential of oleogels as a tool for fat replacement and bodyweight management.

MSc Tiago C. Pinto, who is working as a doctoral researcher for the iOLEO project, under the supervision of Docent Fabio Valoppi, carefully oversaw the planning of this intensive study. After months of painstakingly planning the work, the 48-hour experiment took place at the XRD1 beamline, with the intent of shedding light on the evolution of lipid crystals contained in engineered oleogel-based emulsions during simulated gastrointestinal digestion. This very ambitious experiment encompassed the in-situ analysis of 16 emulsion formulations with different lipid core materials and emulsifiers, each of them requiring at least 4 hours of simulated digestion. Time constraints were evident, and the complexity of the experiment required Tiago and Fabio to be joined by MSc Afsane Kazerani Garcia and BSc Christos Papadogiannakis. As they are both working on oleogel-related projects, their proficiency in the lab and familiarity with the topic was very valuable in making this experiment a fruitful one. Cooperation and teamwork were the factors that made this a successful venture, but the ability to keep calm even when things weren’t working in the researchers’ favour was key.

“Keeping the morale up while working two consecutive 20-hour shifts, with a small break of about 4 hours between them is not easy, especially when everything seemed to be stacked against us. After all the months of preparation and planning, having only 48 hours to accomplish everything that I intended brought a lot of pressure. Luckily, we were able to make it through and come out on the other side with very interesting observations. The dataset is still under processing, but we are confident that these are results that can provide a very valuable step towards revolutionising the field.”, Tiago said.

The results are being analysed with the collaboration of beamline scientist Dr. Luisa Barba, whose expertise and availability were essential during the planning and execution of the experiment. After the beam time, the team took a much-deserved day of rest with some exploring of the city of Trieste, as well as a short visit across the border to the historic port town of Koper, in Slovenia.

One of the most prevalent targets in the study of oleogels is their use as a replacement of fats from food chains, with one of the biggest hurdles being the achievement of similar macroscopic properties to replicate them. The characterisation of matter via X-rays can reveal structural differences at the molecular level that justify macroscopic properties and their variations. X-rays are an invaluable probe of the structure of matter, and the range of problems where X-rays have proved to be decisive in unravelling a material structure is very wide. In this case, understanding the evolution of lipid crystals (lipid crystal size, shape, and polymorphic form) will allow a better design of emulsions, leading to a tailored lipid digestion and release. This knowledge is of paramount importance when designing and developing engineered emulsions with tailorable digestibility. The synchrotron analysis offers the possibility to structurally characterise matter at many different levels, in a way that wouldn’t be possible using benchtop X-ray diffraction equipment. The level of detail that these results provide will play a pivotal role in understanding the structural response of simple differences in the composition of engineered emulsions.