Options to Improve the Mechanical Properties of Protein-Based Materials.

While bio-based but chemically synthesized polymers such as polylactic acid require industrial conditions for biodegradation, protein-based materials are home compostable and show high potential for disposable products that are not collected. However, so far, such materials lack in their mechanical properties to reach the requirements for, e.g., packaging applications. Relevant measures for such a modification of protein-based materials are plasticization and cross-linking; the former increasing the elasticity and the latter the tensile strength of the polymer matrix. The assessment shows that compared to other polymers, the major bottleneck of proteins is their complex structure, which can, if developed accordingly, be used to design materials with desired functional properties. Chemicals can act as cross-linkers but require controlled reaction conditions. Physical methods such as heat curing and radiation show higher effectiveness but are not easy to control and can even damage the polymer backbone. Concerning plasticization, effectiveness and compatibility follow opposite trends due to weak interactions between the plasticizer and the protein. Internal plasticization by covalent bonding surpasses these limitations but requires further research specific for each protein. In addition, synergistic approaches, where different plasticization/cross-linking methods are combined, have shown high potential and emphasize the complexity in the design of the polymer matrix.

Improved HPLC-method for estimation and correction of amino acid losses during hydrolysis of unknown samples.

Amino acid analysis, commonly done by acid hydrolysis of proteins and HPLC analysis, faces one major problem: incomplete hydrolysis of stable amino acids and degradation of unstable amino acids are causing amino acid losses. As a result, amino acid recovery of unknown samples cannot be estimated. Some methods have been reported for correction of these factors in the past. This paper shows an improved and integrated method to overcome this problem by using stillage as an exemplary unknown sample material. Amino acid recovery from an unknown sample can be estimated by standard addition of a known protein. If the sample does not cause matrix effects during amino acid hydrolysis, recoveries of the standard protein are transferable to the sample. If the sample does cause matrix effects correction of amino acid losses can instead be done by determination of hydrolysis kinetics. Therefore, first order kinetics were used for amino acids that undergo degradation during hydrolysis. For all stable amino acids higher order kinetics were used, a novel approach to determine hydrolysis kinetics. The presented method can be a helpful tool for scientists who want to optimize amino acid analysis of a particular biomass substrate.

Biogas plants as key units of biorefinery concepts: Options and their assessment.

In order to minimize the environmental impacts of growing population, progressive exploitation of fossil resources and negative consequences of climate change the politically intended goal is to successively transform our primarily oil-based into a bio-based economy. Hence, one goal is to significantly reduce the utilization of fossil resources by increasing the use of renewable energy and resources (i.e. biomass) and the efficiency of their conversion processes. Including existing technologies into the development of future concepts could accelerate the transition to a bio-economy. As one solution integrated biorefinery concepts based on agricultural biogas plants are discussed, which convert biomass with minimal energy consumption to a multitude of products without generating waste. However, they still have huge potential in terms of increased biomass utilization. In that context, catch crops offer interesting opportunities as a substrate for those biorefineries, since they support soil regeneration while generating additional products for the bio-economy without increasing land use. In this study a selection of significant indicators was chosen in order to determine the environmental effectivity and economic efficiency of these biorefinery concepts by a systematic assessment of possible process schemes. Thus within this study the usability of the chosen indicators and the potential of catch crops in advanced biorefineries is assessed.