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A holistic utilization of all lignocellulosic wood biomass, instead of the current approach of using only the cellulose fraction, is crucial for the efficient, ecological, and economical use of the forest resources. Use of wood constituents in the food and feed sector is a potential way of promoting the global economy. However, industrially established food products utilizing such components are still scarce, with the exception of cellulose derivatives. Hemicelluloses that include xylans and mannans are major constituents of wood. The wood hemicelluloses are structurally similar to hemicelluloses from crops, which are included in our diet, for example, as a part of dietary fibers. Hence, structurally similar wood hemicelluloses have the potential for similar uses. We review the current status and future potential of wood hemicelluloses as food ingredients. We include an inventory of the extraction routes of wood hemicelluloses, their physicochemical properties, and some of their gastrointestinal characteristics, and we also consider the regulatory route that research findings need to follow to be approved for food solutions, as well as the current status of the wood hemicellulose applications on that route.

Beneficial modulation of the gut microbiome has high-impact implications not only in humans, but also in livestock that sustain our current societal needs. In this context, we have engineered an acetylated galactoglucomannan (AcGGM) fibre from spruce trees to match unique enzymatic capabilities of Roseburia and Faecalibacterium species, both renowned butyrate-producing gut commensals. The accuracy of AcGGM was tested in an applied pig feeding trial, which resolved 355 metagenome-assembled genomes together with quantitative metaproteomes. In AcGGM-fed pigs, both target populations differentially expressed AcGGM-specific polysaccharide utilization loci, including novel, mannan-specific esterases that are critical to its deconstruction. We additionally observed a “butterfly effect”, whereby numerous metabolic changes and interdependent cross-feeding pathways were detected in neighboring non-mannolytic populations that produce short-chain fatty acids. Our findings show that intricate structural features and acetylation patterns of dietary fibre can be customized to specific bacterial populations, with the possibility to create greater modulatory effects at large.

Lytic polysaccharide monooxygenases are copper-dependent enzymes that perform oxidative cleavage of glycosidic bonds in cellulose and various other polysaccharides. LPMOs acting on cellulose use a reactive oxygen species to abstract a hydrogen from the C1 or C4, followed by hydroxylation of the resulting substrate radical. The resulting hydroxylated species is unstable, resulting in glycoside bond scission and formation of an oxidized new chain end. These oxidized chain ends are spontaneously hydrated at neutral pH, leading to formation of an aldonic acid or a gemdiol, respectively. LPMO activity may be characterized using a variety of analytic tools, the most common of which are high-performance anion exchange chromatography system with pulsed amperometric detection (HPAEC-PAD) and MALDI-TOF mass spectrometry (MALDI-MS). NMR may be used to increase the certainty of product identifications, in particular the site of oxidation. Kinetic studies of LPMOs have several pitfalls and to avoid these, it is important to secure copper saturation, avoid the presence of free transition metals in solution, and control the amount of reductant (i.e., electron supply to the LPMO). Further insight into LPMO properties may be obtained by determining the redox potential and by determining the affinity for copper. In some cases, substrate affinity can be assessed using isothermal titration calorimetry. These methods are described in this chapter. This is a post-peer-review, pre-copyedit version of an article published in Methods in molecular biology Locked until 1.6.2019 due to copyright restrictions. The final authenticated version is available online at: https://doi.org/10.1007/978-1-4939-7877-9_16

Fungi secrete a set of glycoside hydrolases and lytic polysaccharide monooxygenases (LPMOs) to degrade plant polysaccharides. Brown-rot fungi, such as Gloeophyllum trabeum, tend to have few LPMOs, and information on these enzymes is scarce. The genome of G. trabeum encodes four auxiliary activity 9 (AA9) LPMOs (GtLPMO9s), whose coding sequences were amplified from cDNA. Due to alternative splicing, two variants of GtLPMO9A seem to be produced, a single-domain variant, GtLPMO9A-1, and a longer variant, GtLPMO9A-2, which contains a C-terminal domain comprising approximately 55 residues without a predicted function. We have overexpressed the phylogenetically distinct GtLPMO9A-2 in Pichia pastoris and investigated its properties. Standard analyses using high-performance anion-exchange chromatography–pulsed amperometric detection (HPAEC-PAD) and mass spectrometry (MS) showed that GtLPMO9A-2 is active on cellulose, carboxymethyl cellulose, and xyloglucan. Importantly, compared to other known xyloglucan-active LPMOs, GtLPMO9A-2 has broad specificity, cleaving at any position along the β-glucan backbone of xyloglucan, regardless of substitutions. Using dynamic viscosity measurements to compare the hemicellulolytic action of GtLPMO9A-2 to that of a well-characterized hemicellulolytic LPMO, NcLPMO9C from Neurospora crassa revealed that GtLPMO9A-2 is more efficient in depolymerizing xyloglucan. These measurements also revealed minor activity on glucomannan that could not be detected by the analysis of soluble products by HPAEC-PAD and MS and that was lower than the activity of NcLPMO9C. Experiments with copolymeric substrates showed an inhibitory effect of hemicellulose coating on cellulolytic LPMO activity and did not reveal additional activities of GtLPMO9A-2. These results provide insight into the LPMO potential of G. trabeum and provide a novel sensitive method, a measurement of dynamic viscosity, for monitoring LPMO activity.

Fungi secrete a set of glycoside hydrolases and lytic polysaccharide monooxygenases (LPMOs) to degrade plant polysaccharides. Brown-rot fungi, such as Gloeophyllum trabeum, tend to have few LPMOs, and information on these enzymes is scarce. The genome of G. trabeum encodes four auxiliary activity 9 (AA9) LPMOs (GtLPMO9s), whose coding sequences were amplified from cDNA. Due to alternative splicing, two variants of GtLPMO9A seem to be produced, a single-domain variant, GtLPMO9A-1, and a longer variant, GtLPMO9A-2, which contains a C-terminal domain comprising approximately 55 residues without a predicted function. We have overexpressed the phylogenetically distinct GtLPMO9A-2 in Pichia pastoris and investigated its properties. Standard analyses using high-performance anion-exchange chromatography–pulsed amperometric detection (HPAEC-PAD) and mass spectrometry (MS) showed that GtLPMO9A-2 is active on cellulose, carboxymethyl cellulose, and xyloglucan. Importantly, compared to other known xyloglucan-active LPMOs, GtLPMO9A-2 has broad specificity, cleaving at any position along the β-glucan backbone of xyloglucan, regardless of substitutions. Using dynamic viscosity measurements to compare the hemicellulolytic action of GtLPMO9A-2 to that of a well-characterized hemicellulolytic LPMO, NcLPMO9C from Neurospora crassa revealed that GtLPMO9A-2 is more efficient in depolymerizing xyloglucan. These measurements also revealed minor activity on glucomannan that could not be detected by the analysis of soluble products by HPAEC-PAD and MS and that was lower than the activity of NcLPMO9C. Experiments with copolymeric substrates showed an inhibitory effect of hemicellulose coating on cellulolytic LPMO activity and did not reveal additional activities of GtLPMO9A-2. These results provide insight into the LPMO potential of G. trabeum and provide a novel sensitive method, a measurement of dynamic viscosity, for monitoring LPMO activity. IMPORTANCE Currently, there are only a few methods available to analyze end products of lytic polysaccharide monooxygenase (LPMO) activity, the most common ones being liquid chromatography and mass spectrometry. Here, we present an alternative and sensitive method based on measurement of dynamic viscosity for real-time continuous monitoring of LPMO activity in the presence of water-soluble hemicelluloses, such as xyloglucan. We have used both these novel and existing analytical methods to characterize a xyloglucan-active LPMO from a brown-rot fungus. This enzyme, GtLPMO9A-2, differs from previously characterized LPMOs in having broad substrate specificity, enabling almost random cleavage of the xyloglucan backbone. GtLPMO9A-2 acts preferentially on free xyloglucan, suggesting a preference for xyloglucan chains that tether cellulose fibers together. The xyloglucan-degrading potential of GtLPMO9A-2 suggests a role in decreasing wood strength at the initial stage of brown rot through degradation of the primary cell wall.

Det er påvist at noen glykosylerte fenoler har prebiotiske effekter. I denne oppgaven ble syntese av 4-formyl-2-metoksifenyl-D-glukopyranosid fra D-glukose og vanillin forsøkt utført ved fem ulike lineære synteseveier. Hensikt var å komme fram til en generell metode for syntese av fenoliske glykosider. Utgangsstoffet D-glukose ble beskyttet og omdannet til ulike glykosyldonorer eller brukt uten beskyttelsesgrupper ved anvendelse av koblingsreagenset 1,3-dimetyl-2-klorimidazoliniumklorid for glykosylering av vanillin. Glykosyleringsreaksjon i bifasisk system med basisk vannfase med glykosyldonoren 2,3,4,6-tetra-O-acetyl-Dglukopyranosylbromid gav eneste isolerbare resultat med tilfredsstillende utbytte. Avbeskyttelse av acetylbeskyttelsesgruppene gav målmolekylet 4-formyl-2-metoksifenyl-Dglukopyranosid. Syntesen hadde et totalutbytte på 42%. Vellykket glykosyleringsmetode ble overført til vanillinglykosider med mannose som karbohydratdel. Både mannose som monomer og blanding av oligomerer ble forsøkt koblet til vanillin. Dannelse av korresponderende glykosider ble påvist, men ikke isolert. Den vellykkede glykosyleringsmetoden ble også overført til reaksjon mellom glykosyldonoren 2,3,4,6-tetra-O-acetyl-D-galaktopyranosylbromid og aglykonet p-nitrofenol. Denne reaksjonen hadde et utbytte på 75%, betydelig høyere enn for reaksjon med vanillin. Difenolen matairesinol ble forsøkt glykosylert med glukose ved tre metoder. Ulikheter i metodene baserte seg på type beskyttelsesgruppe og utgående gruppe. Tidligere vellykket glykosyleringsmetode gav antydning til produktdannelse av matairesinol-4,4-di-2,3,4,6-tetra- O-acetyl-D-glukopyranosid. Det var imidlertid ikke mulig å isolere glykosidet fordi det ikke ble bevart gjennom opprensingstrinnet. Derfor ble ikke avbeskyttelsestrinnet gjennomført. De fenoliske dihydropyridinene 3,5-pyridindikarboksylsyre-1,4-dihydro-4-(4-hydroksy-3- metoksifenyl)-2,6-dimetyl-3,5-dietylester og 3,5-pyridindikarboksylsyre-1,4-dihydro-4-(4- hydroksyfenyl)-2,6-dimetyl-3,5-dietylester ble forsøkt glykosylert med glukose med glykosyldonoren 2,3,4,6-tetra-O-acetyl-D-glukopyranosylbromid i bifasisk system med basisk vannfase. Karakterisk topp for anomert karbon ble observert i 13C NMR-spektra, og antydet vellykket kobling. Forbindelsene var imidlertid ikke isolerbare. Dermed kan det ikke sies med sikkerhet at glykosyleringsreaksjonen gav ønskede glykosider. På basis av mislykket renframstilling etter glykosylering kunne ikke avbeskyttelsestrinnet gjennomføres. Some glycosylated phenols have been shown to have prebiotic effects. In this thesis, synthesis of 4-formyl-2-methoxyphenyl-D-glucopyranoside from D-glucose and vanillin was attempted by five different linear synthetic routes. The intention was to find a general method for the synthesis of phenolic glycosides. The starting material D-glucose was protected and converted to various glycosyl donors or used without protecting groups using the coupling reagent 2-chloro-1,3-dimethylimidazolinium chloride for glycosylation of vanillin. Glycosylation reaction in a biphasic system with a basic water phase and using the glycosyl donor 2,3,4,6-tetra-O-acetyl-D-glucopyranosyl bromide gave the only isolatable product with satisfactory yield. Deprotection of the acetyl protecting groups gave the target molecule 4-formyl-2-methoxyphenyl-D-glucopyranoside. The synthesis had a total yield of 42%. Successful glycosylation method was converted to vanillin glycosides with mannose as carbohydrate moiety. Attempts were made to connect both mannose as a monomer and a mixture of oligomers to vanillin. Formation of corresponding glycosides was detected but not isolated. The successful glycosylation method was also converted to a reaction between the glycosyl donor 2,3,4,6-tetra-O-acetyl-D-galactopyranosyl bromide and the aglycone p-nitrophenol. This reaction had a yield of 75%, considerably higher than for the reaction with vanillin. It was attempted to glycosylate the diphenol matairesinol with glucose by three methods. Differences in the methods were based on the type of protection group and the leaving group. Previously successful glycosylation method gave rise to product formation of matairesinol-4,4-di-2,3,4,6-tetra-O-acetyl-D-glucopyranoside. However, it was not possible to isolate the glycoside due to it not being preserved during the purification step. Therefore, the deprotection step was not executed. The phenolic dihydropyridines 3,5-pyridinedicarboxylic acid 1,4-dihydro-4- (4-hydroxy-3-methoxyphenyl) -2,6-dimethyl-3,5-diethyl ester and 3,5-pyridinedicarboxylic acid 1,4-dihydro -4- (4-hydroxyphenyl) -2,6-dimethyl-3,5-diethyl ester was also attempted glycosylated with glucose with the glycosyl donor 2,3,4,6-tetra-O-acetyl-D-glucopyranosyl bromide in a biphasic system with a basic water phase. Characteristic peak for anomeric carbon was observed in 13C NMR spectra, indicating successful coupling. However, the compounds were not isolatable. Thus, it cannot be said with certainty that the glycosylation reaction yielded desired glycosides. Due to an unsuccessful purification step after the glycosylation reaction, the deprotection step could not be performed. M-KB

In the first stage of life infants go through rapid growth and development and have high nutritional needs. During this first 6 months of life breast milk is considered to provide a complete postnatal nutrition. Positive benefits of breastmilk have been extensively documented and it is a known fact that breastfed infants show a domination of Bifidobacterial species in the gut. The colonization pattern has been revealed to be majorly affected by human milk oligosaccharides (HMOs) found in breast milk. HMOs are not digested by the infant and will as a result reach the colon where different strains of Bifidobacteria metabolise them and produce metabolites, mainly in the form of short chain fatty acids (SCFA) where some might be beneficial to the host. The study included seven different Bifidobacteria strains that were test grown in five different mediums with different carbon sources with a total of 42 samples repeated in three parallels. DNA quantification was performed with the use of qPCR and short chain fatty acid profiles were measured with the use of high-performance liquid chromatography. In conclusion the results demonstrated differences in HMO utilization and SCFA production among the different strains. It was clearly demonstrated that Bifidobacterium longum subsp. Infantis has the best utilization and growth abilities on HMOs which may reflect their abundance in the infant gut. The main metabolite of carbohydrate fermentation performed by Bifidobacteria strain was acetic acid and the results also confirmed that the most common infant type Bifidobacteria strains are the main producers of lactic acid. I den første fasen av livet går spedbarn igjennom rask vekst og utvikling og har dermed et høyt ernæringsbehov. I de første 6 leve månedene anses morsmelk til å være en fullverdig næringskilde for spedbarnet. Det har blitt omfattende dokumentert at morsmelk gir positive helseutfall og at brysternærte barn har en dominerende populasjon av Bifidobakterie arter i tarmen hvor denne spesifikke koloniseringsprosessen har vist seg å være i stor grad påvirket av oligosakkarider funnet i morsmelk. Melke oligosakkaridene er ufordøyelige for spedbarnet og vil dermed ende i tykktarmen hvor de kan bli metabolisert av ulike Bifidobakterielle stammer. Deres metabolitter er hovedsakelig i form av kort kjedede fettsyrer der noen kan være gunstige for verten. Studien inkluderte syv forskjellige Bifidobakterie-stammer som ble testet i fem forskjellige medier tilsatt ulike karbon kilder. Det var totalt 42 prøver gjentatt i tre paralleller. DNAkvantifisering ble utført ved bruk av qPCR og kortkjedede fettsyreprofiler ble målt med høyytelsesvæskekromatografi. Resultatene demonstrerte forskjeller i oligosakkarid utnyttelse samt kort kjeda fettsyre produksjon av de ulike stammene. Resultatene viste at Bifidobacterium longum subsp. Infantis hadde best utnyttelses og vekstevne av oligasakkaridene, resultatet kan dermed trolig gjenspeile stammes overflod i tarmen hos spedbarn. Hoved metabolitten etter oligosakkarid fermentering var vist å være eddikksyre og resultatene bekreftet også at de vanligste stammene funnet hos spedbarn er de samme stammene som er de viktigste produsentene av melkesyre. M-MAT

Yeasts are known to be sources of highly quality proteins and exopolysaccharides (EPS). The main goal in this study was to produce and process yeasts of biotechnological interest to investigate whether these species can be used as supplements in food and feeds. Candida utilis, Wickerhamomyces anomalus and Arxula adeninivorans were fermented several times on chicken meat hydrolysate and downstream processed to be able to characterize the cell walls of the yeast, measure the protein content, and to discover the bottlenecks in the different processing steps. The results from the protein analysis showed that W. anomalus and A. adeninivorans contained a higher amount of proteins than C. utilis. All the yeasts had glucose, mannose and N-acetyl-glucosamine in their cell walls according to the monosaccharide composition analysis. These monosaccharides are building blocks in the exopolysaccharides b-glucan, mannan and chitin. Earlier performed studies have reported that these exopolysaccharides often are percent in the yeast cell wall. The results from this study indicates that b-glucan, mannan and chitin are present in the cell walls of C. utilis, W. anomalus and A. adeninivorans as well. In addition, galactose was found in the cell wall of A. adeninivorans. In total seven downstream processing steps were performed on W. anomalus after optimization of the process. The final processing steps were; 2-phase separation, cell disruption, enzymatic treatment, acid treatment, centrifugation, ultrafiltration and nanofiltration. The obtained fractions after the filtrations contained both proteins and carbohydrates. In depth analysis of these fractions are subjected to ongoing analysis in the lab. Gjær er kilder til proteiner med høy kvalitet og eksopolysakkarider (EPS). Hovedmålene med dette studiet var å produsere og prosessere gjær av bioteknologisk interesse for å undersøke om gjæren kan brukes som tilskudd in mat og fôr. Candida utilis, Wickerhamomyces anomalus og Arxula adeninivorans ble fermentert flere ganger med hydrolyserte kyllinginnvoller som vekstmedia, og nedstrøms-prosessert for å kunne karakterisere celleveggen til artene, måle proteininnholdet, og detektere eventuelle flaksehalser i prosesserigsstegene. Resultatene fra proteinanalysen viste at W. Anomalus og A. adeninivorans inneholdt et høyere proteininnhold enn C. utilis. M-KB

The world’s population is increasing and as cities grow in population and area, efficient and safe handling of sewage is becoming increasingly important. Wastewater treatment generates two products; purified water and sewage sludge. More sustainable options than landfilling of untreated sewage sludge and other organic wastes are desired. Technologies such as the anaerobic digestion (AD) process have been employed to convert a portion of the organic material to renewable energy in the form of biogas. The remaining solid residue after AD (digestate) has been reduced in volume and is more attractive for other disposal options such as land application in the agricultural sector. To minimize the amount of water in the digestate before transportation, solids are separated from the water in a dewatering process. Technologies such as the thermal hydrolysis process (THP) have been developed to increase biogas production and improve dewatering. The amount of water removed from the digestate has a substantial impact on the volume of dewatered cake and thus the transportation costs. It is therefore important to understand the mechanisms underlying the dewatering process. This thesis aimed at improving the understanding of why digestates dewater differently, how this can be predicted and what the effect of the THP is, either in front of AD (Pre-AD THP) or after AD (Post-AD THP). A wide range of digestates from 35 commercial full-scale plants were collected as a part of this study. This study is based on five research papers, which gave the following main results: Overall, the AD substrate composition was shown to highly influence the dewatered cake solids from digestates with conventional AD, Pre-AD THP and Post-AD THP. Thermogravimetric analysis (TGA) was used to predict dewatered cake solids by measuring the free water content. Different dewatering devices produced different cake solids despite having similar free water content, however, the impact was minimal compared to the impact of differences in digestate physicochemical parameters. A universal factor describing the water retention capacity of the digestate was identified and termed C/N•ash. This factor was found to correlate linearly with the predicted cake solids by TGA when plants with conventional AD were separated from Pre-AD THP plants. Moreover, when applied to full-scale data, the C/N•ash was found to correlate linearly with both dewatered cake solids and the polymer dose used in the dewatering process. Both Pre-AD THP and Post-AD THP were found to improve predicted cake solids of dewatered digestate by increasing the amount of free water. Post-AD THP gave bigger improvement in cake solids than Pre-AD THP. Centrifuging the Post-AD THP digestate at 80 °C increased the dewatered cake solids compared to predictions by TGA at 35 °C. The substrate composition also influenced the amount of melanoidin-associated compounds in Pre-AD THP digestate quantified as the concentrations of soluble colloidal chemical oxygen demand, color and dissolved organic nitrogen. Post-AD THP results in a sterilized biosolid fraction where pathogens can grow without microbial competition if recontaminated during storage and handling. This scenario was efficiently mitigated by the addition of a mixed microbial community from compost to the dewatered biosolids. The compost added a robust and diverse microbial community capable of outcompeting the added Escherichia coli and suppressing its’ growth in Post-AD THP biosolids. The results provide a simple solution for control of pathogen recontamination. Overall, this study has identified a parameter that can easily be measured in a commercial laboratory providing information on the water holding capacity of digestates. Predictive tools have been developed and the effect of sludge composition on both dewaterability and the concentration of melanoidin-associated compounds have been quantified. A solution to control pathogen growth in Post-AD THP biosolids has been thoroughly verified showing increased robustness of compost-inoculated biosolids. Med en økende verdensbefolkning og større byer er det viktig med et effektivt og trygt system for å håndtere avløp og kloakk. Rensing av kloakk gir to produkter; renset vann og slam. Andre alternativer enn å deponere ubehandlet slam og andre organiske avfallsstrømmer er ønskelig og teknologier som anaerob utråtning har blitt brukt til å konvertere deler av det organiske materialet til fornybar energi i form av biogass. Den faste fraksjonen som er igjen etter anaerob utråtning (råtnerest) har da blitt redusert i volum, stabilisert og er et mer attraktivt produkt for annet bruk, som for eksempel gjødsel i landbruket. For å redusere vannmengden i råtneresten før transport blir den faste fraksjonen separert fra vann fraksjonen i avvanningsprosessen. Teknologier som den termisk hydrolyse prosessen (THP) har blitt utviklet for å øke biogass produksjonen og forbedre avvanningen. Mengden av vann som kan bli separert fra råtneresten har stor betydning for volumet av avvannet kake som må transporteres og kostnadene forbundet med dette. Derfor er det viktig å forstå de styrende mekanismene bak denne prosessen. Denne avhandlingen ønsket å forbedre forståelsen av hvorfor råtnerester avvanner ulikt, hvordan dette kan måles og effekten av THP enten før eller etter anaerob utråtning. Et bredt spekter av råtnerester fra 35 kommersielle full-skala anlegg ble samlet inn i løpet av dette prosjektet for å studere forskjeller mellom ulike anlegg. Denne avhandlingen er basert på fem forskningsartikler som ga følgende resultater: Substratet som går til utråtning har stor innflytelse på tørrstoff konsentrasjonen av avvannet kake. Dette gjaldt for råtnerester fra vanlig utråtning og råtnerester med THP før eller etter råtnetanken. Termogravimetrisk analyse (TGA) ble brukt til å predikere tørrstoffkonsentrasjonen av avvannet kake ved å måle mengden fritt vann. Ulike avvanningsmaskiner ga ulike tørrstoffkonsentrasjoner i avvannet kake selv med lignende innhold fritt vann i råtneresten, men denne effekten var liten sammenlignet med forskjellene i fysiske og kjemiske parametere. En universell faktor som reflekterte vannbindingsevnen til råtneresten ble funnet og kalt C/N•ash. En lineær korrelasjon ble funnet mellom denne faktoren og predikert tørrstoffkonsentrasjon av avvannet kake når konvensjonelle utråtningsprosesser ble separert fra de med THP før råtnetanken. Det ble også funnet lineære sammenhenger mellom C/N•ash og avvannet kake og polymerforbruk fra full-skala avvanningsprosesser med THP før råtnetanken. THP både før og etter råtnetanken økte predikert tørrstoffkonsentrasjon i avvannet kake ved å øke andelen fritt vann i råtneresten. THP etter råtnetanken ga den største forbedringen i avvannet kake sammenlignet med THP før råtnetanken. Direkte avvanning etter THP av utråtnet slam viste at tørrstoffkonsentrasjonen av avvannet kake kunne ytterligere forbedres ved å sentrifugere på 80 °C sammenlignet med TGA prediksjoner ved 35 °C. Substratsammensetningen påvirket konsentrasjoner av Maillard produkter målt som løst kolloidalt kjemisk oksygenforbruk, farge og løst organisk nitrogen i råtnerester med THP før råtnetanken. Inokulering av sterilisert råtnerest med aktiv mikroflora fra kompost i to dager eliminerte vekst av Escherichia coli (E. coli) etter rekontaminering. Dette kan være en effektiv strategi for å beskytte mot rekontaminering. Oppsummert har denne studien kommet frem til en parameter som kan måles i kommersielle laboratorier og brukes til å beskrive vannbindingsevnen til ulike råtnerester. Modeller for å predikere tørrstoff av avvannet kake har blitt utviklet og substratblandingens innvirkning på avvanning og produkter fra Maillard reaksjonen har blitt studert. En løsning for å eliminere vekst av E. coli i steril råtnerest har blitt verifisert og viste økt motstandsdyktighet mot rekontaminering ved inokulering med kompost. The Research Council of Norway