Food Materials Science Research Group – Blog

The Food Materials Science research group continues to innovate in the use of Nordic forest resources in advanced applications for food and other novel materials. For this, a deep understanding on the chemical and structural aspects of wood components is crucial. Assessment of cellulose, hemicelluloses, and lignin alone is needed, but also the identification and elucidation of linkages between those structures: the so-called lignin-carbohydrate complexes (LCCs). Despite of paramount importance for applications, the identification of LCC bonds is challenging because of their relatively low frequency in wood extracts.

A recent research article by Danila Carvalho et al. tackled this challenge and improved the identification of LCC bonds in spruce hot water extract using an elegant combination of fractionation techniques, including chemical, enzymatic, and physical methods. Such techniques resulted in the fractionation of LCC bonds and enabled the identification of three types of LCCs, namely: phenylglycoside (PG), benzylether (BE) and gamma-ester (GE). This research developed an efficient analytical methodology for LCC identification, which may facilitate the study of LCC functionalities and, consequently, open novel opportunities of applications for wood-based derivatives.

This research was a result of the collaborative project: “Role of lignin carbohydrate complexes as key to stable emulsions” (ROCK), funded by Tandem Forest Values programme by Kungliga Skogs- och Lantbruksakademien (KSLA), Sweden, and led by Assist. Prof. Kirsi Mikkonen (University of Helsinki, Finland) and Assoc. Prof. Martin Lawoko (Royal Institute of Technology, Sweden).

The open access article is available here.

The Food Materials Science group studies the applicability of spruce gum in dispersion-based systems, such as food, beverages, cosmetics, and chemicals. To formulate applications of spruce gum to produce high quality products, knowledge on its solution properties is very essential.

A recently published article by Mamata Bhattarai et al. reveals that spruce gum forms higher-order structures in water, such as aggregates and colloidal particles. We demonstrated this, for the first time, by fractionating and studying all the fractions of spruce gum using asymmetric field-flow fractionation and a combination of light scattering and electron microscopy.

Spruce gum is mainly composed of galactoglucomannan polysaccharides, but also other structures are co-extracted from spruce wood with the polysaccharides. Unpurified spruce gum containing high levels of lignin occurred in water in the form of polysaccharide-aggregate-particle mixture. Spruce gum after purification by ethanol precipitation did not show particles, but the aggregates still existed. Characterization of this unique mixture of spruce gum was challenging; thus, several parameters during the analytical fractionation had to be optimized. The article discusses several aspects about challenges to fractionate complex polysaccharide mixtures and possible approaches to address them.

The work was a result of excellent collaboration between the FoMSci group (Department of Food and Nutrition, University of Helsinki), Department of Physics (University of Helsinki), and the University of Natural Resources and Life Sciences (BOKU), Austria.

The article is available as open access here.

Think about expanded polystyrene and try to imagine something that works like polystyrene, but is much more environmentally friendly, very sustainable, and an economic material.

Fungal mycelia are versatile, highly productive, and sustainable sources for biocomposites to replace conventional plastics. However, only a few fungal strains have been characterized in composites and numerous strains remain unexplored. Many plant residue materials, such as side streams from food production could be used as feeding substrates for mycelia. A research article by Zeynep Tacer-Caba et al. explored this field and studied novel fungal strains, feeding substrates, and dynamic mechanical properties of mycelium composites for the first time at a broad moisture gradient. The research was conducted within the Academy of Finland –funded project Reassembly of fungal polysaccharides for biocompatible interfaces (REPLY). 

The champion of novel mycelium composites, Agaricus bisporus, gave high stiffness and moisture-resistance. The dense structure and rich chemical composition of rapeseed cake made it a potent feeding substrate for mycelia. In this work, the compressive strength of mycelium composites ranged between 17 and 300 kPa. Therefore, mycelium composites may be considered as competitors of expanded polystyrene, as the latter have similar compressive strength (69–400 kPa).

 All tested mycelia composites, either with rapeseed cake or oat husk as feeding substrates, had rather low water uptake at moderate ambient humidity. Therefore, all samples – irrespective of the mycelium and substrate types – seemed to be resilient to moisture. Will future packaging be grown from fungi?