Baking Gradients Cause Heterogeneity in Starch and Proteins in Pound Cake

peer reviewedWe investigated the impact of temperature and moisture gradients on starch gelatinization and egg denaturation, and on protein extractabilities during cake baking. Differences in crumb structure in the center, top, and bottom zones of cake as measured with X-ray microfocus-computed tomography were successfully related to the moment at which starch gelatinized and protein aggregated during baking, which stiffened the cell walls. The temperature in the top and bottom zones of cake increased faster than in the center of the cake due to facilitated heat transfer. This resulted in lower water availability in top and bottom zones, leading to incomplete gelatinization of starch after baking in these zones. In the top zone, extended starch gelatinization and protein polymerization led to later cell wall formation, resulting in a broader cell size distribution. The bottom zone of cake reached the highest temperatures during baking with more substantial starch gelatinization and egg denaturation within the first 25 min of baking. During the final 20 min of baking, little if any change in gelatinization enthalpy and protein extractability was found due to the very low water availability in this region. The bottom zone of the crumb showed a broader cell wall size distribution, which was associated with more collapse. All in all, the results illustrate that cake crumb is not a homogeneous material

Lignin-Based Additives for Improved Thermo-Oxidative Stability of Biolubricants

There is an environmental concern regarding the use of petroleum-based lubricants, which are generally toxic and nonbiodegradable. Biobased lubricants, such as vegetable oils, are the alternative: they show excellent lubricity, are readily biodegradable and nontoxic. However, a major disadvantage of using vegetable oils in lubricant applications is their lack of thermo-oxidative stability, which can be improved by antioxidant additives. Here, we propose the use of lignin-based additives in biolubricant formulations to improve this feature, based on lignin's known antioxidant properties. To ensure a stable dispersion in vegetable oil, lignin was partially esterified. Antioxidant properties of lignin before and after palmitoylation were demonstrated in a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Four different lignin-based fractions, commercial Protobind P1000 soda lignin from straw, solvolytically fractionated Protobind P1000 lignin and two lignin fractions from reductively catalyzed fractionation (RCF) of native birch wood, were tested in biolubricant formulations with castor oil as base oil. Those lignin fractions exhibited excellent performance compared to butylated hydroxytoluene (BHT), a commonly used petroleum-based antioxidant. Formulations of modified lignin in castor oil possess improved thermo-oxidative stability, as illustrated by their increased oxidation induction time. Additionally, rheological and tribological tests demonstrate similar, or in some cases improved, lubricating properties compared to castor oil. This study showcases the successful incorporation of lignin-based antioxidants in biolubricant formulations, tackling the major disadvantage of vegetable oils as environment-friendly lubricants

Reductive lignocellulose fractionation into soluble lignin-derived phenolic monomers and dimers and processable carbohydrate pulps

© The Royal Society of Chemistry 2015. A catalytic lignocellulose biorefinery process is presented, valorizing both polysaccharide and lignin components into a handful of chemicals. To that end, birch sawdust is efficiently delignified through simultaneous solvolysis and catalytic hydrogenolysis in the presence of a Ru on carbon catalyst (Ru/C) in methanol under a H2 atmosphere at elevated temperature, resulting in a carbohydrate pulp and a lignin oil. The lignin oil yields above 50% of phenolic monomers (mainly 4-n-propylguaiacol and 4-n-propylsyringol) and about 20% of a set of phenolic dimers, relative to the original lignin content, next to phenolic oligomers. The structural features of the lignin monomers, dimers and oligomers were identified by a combination of GC/MS, GPC and 2D HSQC NMR techniques, showing interesting functionalities for forthcoming polymer applications. The effect of several key parameters like temperature, reaction time, wood particle size, reactor loading, catalyst reusability and the influence of solvent and gas were examined in view of the phenolic product yield, the degree of delignification and the sugar retention as a first assessment of the techno-economic feasibility of this biorefinery process. The separated carbohydrate pulp contains up to 92% of the initial polysaccharides, with a nearly quantitative retention of cellulose. Pulp valorization was demonstrated by its chemocatalytic conversion to sugar polyols, showing the multiple use of Ru/C, initially applied in the hydrogenolysis process. Various lignocellulosic substrates, including genetically modified lines of Arabidopsis thaliana, were finally processed in the hydrogenolytic biorefinery, indicating lignocellulose rich in syringyl-type lignin, as found in hardwoods, as the ideal feedstock for the production of chemicals.crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: W. J. J. Huijgen (ResearcherID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0) history: Received 20 January 2015; Accepted 20 April 2015; Accepted Manuscript published 20 April 2015; Advance Article published 30 April 2015; Version of Record published 3 June 2015status: publishe