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Chhetri, Jyoti; Falck-Ytter, Anne Bergljot & Strætkvern, Knut Olav
(2023).
Phenolic acids from the leaves of Jerusalem artichoke (Helianthus tuberosus L.): Effect of drying, intensification, and solvent system on yield and antioxidant activity .
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The perennial and tuberous Jerusalem artichoke (JA) is a hardy vegetable growing under almost any condition. Besides its inulin-rich underground tubers, the sunflower-like plant’s aerial parts (leaf, flower, stem) are a rich yet unexploited source of bioactive phytochemicals. The leaves are abundant in various phenolic acids having antioxidant activity. In this study, leaves of JA were harvested from full-grown plants (> 2 m) and subjected to conventional and non-conventional solvent extraction techniques to maximize the yield of phenolic acids. Harvested leaves were either dried or used as fresh. The two solvent systems were aqueous ethanol (55 %) and choline chloride/glucose/water (1:3:30), a natural deep eutectic solvent (NADES) acting through multiple hydrogen bond formation. The techniques compared were maceration at room temperature (ME) and ultrasound-assisted extraction (UAE). For each solvent system, the effect on total phenolics yield (TPC, mg gallic acid eqv./ g dry substance) was tested with both fresh and dried leaves in a two-level full factorial design (n=14) through a combination of varying extraction time (20-60 min) and liquid-to-solids ratio (20-50:1). The extraction output was also assayed as the ferric reducing antioxidant power (FRAP, mM Fe2+ eqv. /g DS).
The main findings are: (1) The drying of JA leaves compared to fresh material improved the TPC yield (3-fold) and FRAP activity (10-20 fold) in aqueous ethanol irrespective of ME and UAE; (2) NADES was a better solvent for extraction giving 5-8 fold higher TPC yields and FRAP activities than with ethanol; (3) the additive effect of UAE was significant (approx. 40 %) only for fresh leaves in NADES, with maximum study values of TPC (15.7) and FRAP (17.7). Overall, drying of the biomass helps the extraction output, likely due to the destabilization and rupture of the leaf cell matrix, improving the mass transfer of phenolic compounds. On the other hand, extraction in NADES – a green solvent, is less dependent on the state of the leaves, probably due to the swelling of cells from water uptake and the subsequent improved mobilization and mass transfer of solutes.
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Klausen, Sarah J.; Falck-Ytter, Anne Bergljot; Strætkvern, Knut Olav & Martín, Carlos
(2023).
Extraction of bioactive compounds and saccharification of polysaccharides for valorization of spent mushroom substrate following a biorefinery approach.
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Strætkvern, Knut Olav
(2022).
En lysende forretning,
Glimt fra Hamars historie - Årbok 2022.
Hamar Historielag.
ISSN 978-82-93109-10-5.
p. 67–84.
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En beretning om firmaet Ingeniør Strætkvern i Storhamargaten 21, og dets grunnlegger Olav Strætkvern (1879-1947) og hustru Marit f.Pedersen (1884-1971). Firmaet, etablert 1921-22, var en av pionerbedriften på Innlandet innenfor elektrobransjen, med et stort virkeområde fra Akershus til Møre. Artikkelen omfatter glimt fra bygnings-, personal-, og firmahistorien gjennom 100 år. Episoder fra krigsårene er også beskrevet.
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Strætkvern, Knut Olav
(2022).
'...til mest verdige personer av Arbeiderklassen...' -Om Severin Olsen Dælin sin bokpremie,
Gammalt frå Stange og Romedal 2022.
Stange historielag.
ISSN 978-82-91366-46-3.
p. 39–49.
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Wetterhus, Elin Merete; Kiran, Nosheen; Falk-Ytter, Anne B.; Nilsson, Astrid & Strætkvern, Knut Olav
(2022).
Concentrated ethanol extracts from potato peel reduce the oxidation of omega-3 and omega-6 fatty acids.
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Strætkvern, Knut Olav
(2021).
Bli med på en reise gjennom vaksinenes historie.
[Newspaper].
Østlendingen og Ringsaker Blad.
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Puss fra sårskorpene ble ført inn under huden på småbarn i alderen ett til fire år, som da ble immune mot kopper. Det var ganske rå vaksinasjonsmetoder den gangen, og mye kunne gå galt, sier professor Knut Olav Strætkvern ved Høgskolen i Innlandet.
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Strætkvern, Knut Olav
(2020).
Stripetegen er vakker, men sier klart ifra - ‘hold avstand’!
Insektnytt.
ISSN 0800-1804.
45(3/4),
p. 19–21.
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Strætkvern, Knut Olav
(2020).
Pilfinkpar med tre ungekull.
Fuglevennen.
ISSN 1504-0623.
17(1),
p. 28–28.
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Strætkvern, Knut Olav & Stana, Astrid
(2019).
Linselusa: Geithamsen (Vespa crabro), vår største veps...
Insektnytt.
ISSN 0800-1804.
44(4),
p. 4–4.
Show summary
Geithamsen (Vespa crabro), vår største veps, sikret seg maksimal eksponering for sin ‘penthouse-leilighet’, da dronningen sist vår etablerte bolet sitt sentralt på denne hytteveggen utenfor Sandefjord (Engeveien, EIS 19). Et modent bol som dette kan romme mellom 650 og 700 individer (wikipedia). Det var imidlertid lav aktivitet ved bolet og ingen tegn til aggresjon da det ble fotografert 1.september; et par geithams kan skimtes ved noen av de mange inngangene (sentralt og oppe til høyre). Veldig ulikt i struktur og farge fra de vanlige gråaktige stikkvepsebolene, framstår dette vakre byggverket med en slags Trump-isk karakter og tilsvarende ‘hair-do’. Foto: Astrid Stana. Tekst: Knut Olav Strætkvern
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Strætkvern, Knut Olav & Strætkvern, Sunniva Briså
(2018).
Linselusa: Hodelusa- Når språkforvirring går til hodet...
Insektnytt.
ISSN 0800-1804.
43(3/4),
p. 4–4.
Show summary
Når språkforvirringen går til hodet …
Sensommeren betyr oppstart og ny aktivitet i skoler og i barnehager, ikke bare gjelder det barna men også Pediculus humanus capitis – hodelusa, som nå finner seg nye formeringsmuligheter. Følgelig skjedde det nylig i en skoleklasse ‘et sted i Norge med sidestilte målformer’, at det kom et brev med til hjemmet fra en bekymret kontaktlærer, om at «hovedlusa» nå var observert. Og om at man måtte ta de nødvendige forholdsregler.
For en stakkars lærer med mange tanker og oppgaver i hodet - eller hovudet, var det nok ikke lett å skille «hovud» fra «hoved». Da det lille kreket nå med ett var titulert som ‘capo de tutti capi(tis) - boss of the bosses’ - eller ‘bawse’ som internett-generasjonen gjerne staver det, MÅTTE det bare avstedkomme følgende illustrative kommentar fra min småkryp-interesserte datter.
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Christensen, Ekaterina & Strætkvern, Knut Olav
(2018).
Boosting biogas with hydrolytic enzymes – effect of cellulase pretreatment of wheat straw on sugar release, onset and ultimate gas production.
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In biogas reactors, hydrolysis of fibrous substrate can be improved by supplementing hydrolytic enzymes, however, reports are not conclusive on this claim. In this study, two commercial preparations consisting of cellulases and hemicellulases, were characterized and tested for their effect on biogas yield. Milled wheat straw was incubated with enzymes in a pretreatment step, prior to mixing with cow’s manure. Following anaerobic digestion (AD), improved gas yield and increased volatile fatty acids VFA) was demonstrated in small scale syringe reactors (100 ml) under various conditions. As a further verification, enzyme pretreatment and AD was scaled up (1.5 L) with optimized conditions. Monitored for extended time, both enzyme-treated reactors performed 16-23% better on gas yield compared to control. Although the increased release of fermentable sugar shortens lag time and lowered volatile solids (VS), enzyme hydrolysis can also cause microbial imbalance compromising reactor pH due to rapid acid accumulation.
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Strætkvern, Knut Olav
(2015).
Hva spiser vi framtiden? Insekter på menyen?
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Iarovitcyna, Ekaterina & Strætkvern, Knut Olav
(2015).
Practical use of cellulase enzymes to improve the frementative conversion of biogas substrate.
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Strætkvern, Knut Olav; Davenne, Tamara; Falck-Ytter, Anne Bergljot & Thøgersen, Jesper
(2015).
Screening by DoE of critical chromatographic variables in the capture of anionic and cationic proteins from industrial potato fruit juice.
Show summary
Ion exchange chromatography is usually predictable in its outcome when setting the system pH at an appropriate distance from the target protein pI. But how predictable is that with a complex feed like potato fruit juice (PFJ)? A voluminous by-product from starch processing, rich in minerals and phytochemicals, PFJ contains proteins (about 1.5%) of both anionic (patatin) and cationic (potato protease inhibitors, PPI) types. In studies to determine optimum capture of both, we examined the influence of critical adsorption factors (pH, ionic strength, flow rate, sample load). Design of Experiments (DoE) was used with two or three factor levels to screen for main effects and possible factor interactions on the protein yield. The patatin group (pI 4.5-5.2) and the PPI group (pI ca. 6.5-9) were captured from PFJ on bioprocess ion exchange resins, anionic and cationic respectively, using lab scale columns (1, 5 and 25ml). Lab scale-up of the chromatography to validate the capture process was facilitated with a 250 ml radial flow chromatography (RFC) column. For the PPI capture, the process was transferred to a 10 liter pilot scale RFC column in a starch processing plant. Analysis of patatin capture showed that ionic strength was a more determinative factor than pH, where optimum binding was favored around pH 7-7.5 and 6-7 mS/cm. Screening of PPI capture revealed that acidic pH 3.5-4 was advantageous, as expected from the overall pI-values. However, ionic strength above 7 mS/cm significantly improved the protein yield, which may indicate favorable ionic shielding effects. In both types of chromatography, the loading flow rate, instead of impairing the mass transfer, showed a positive correlation with protein yield over the range 250-650 cm/h and 450-900 cm/h, respectively. This observation made use of RFC even more desirable, since the column geometry provides low back pressures at high flow rates. However, in the RFC scale-up of patatin capture on anion exchanger, significant interaction effects between sample load (negative) and flow rate (positive) was observed. In the RFC scale-up of PPI capture on cation exchanger, although binding kinetics is rapid, extended column residence time (0.4 vs 0.8 min) showed to be a more important factor than keeping a high flow rate during loading. This was confirmed when transferring from lab to pilot scale RFC columns, both with 12 cm bed depth. Overall, optimum conditions for capture of potato proteins were efficiently obtained through the screening process, resulting in consistent protein yields.
KEY WORDS: Potato proteins - Design of experiments - Ion exchange chromatography - Radial flow column
HIGHLIGHTS:
* Potato fruit juice is an interesting system to for capture of high abundance proteins.
* With DoE unexpected interaction effects were observed for ionic strength and flow rate
* Radial flow columns enhanced capture probably due to better sample-resin interaction.
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Chernakova, Elena & Strætkvern, Knut Olav
(2013).
Potato proteins captured on a mixed mode resin: an optimization and scale up study using predictions.
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Background: The increased interest in the use of plant proteins in food products as an alternative functional ingredients to animal proteins, has called for efficient methods to isolate valuable fractions. Potato proteins represent a source of valuable industrial proteins, especially when harvested from the fruit juice of starch processing. Mixed mode chromatographic resins offer multiple adsorption sites even at increased ionic content, and thus have proven successful in capturing proteins from industrial by-streams. Aim: To successfully employ chromatographic capture in production of functional industrial proteins, conditions should be sought where most of the soluble proteins are recovered in a single passage. In this study we used modeling tools of protein surface determinants to optimize the capture of major potato proteins on the Capto Mixed Mode Cation resin (GE Healthcare). Methods: Theoretical prediction of binding behavior of patatin (80 kDa) and a selection of the various protease inhibitors (18-22 kDa) was carried out using bioinformatic web tools (PROPKA, Kyte-Doolitte scale plot, APBS and PyMol). Alignment of pH-dependent surface electrostatic and hydropathicity densities of the major protein fractions was used to set ranges of pH values to be tested. Results: Binding experiments on Capto MMC miniature columns and SDS-PAGE analysis confirmed that maximum binding occurred in the overlapping pH-range where proteins were dominantly positively charged. Further testing verified that the binding of patatin was less sensitive to changes in ionic strength as predicted from its hydrophobicity. This indicates patatin binding to MMC preferentially through the ligand’s hydrophobic domain. Design of Experiments (DoE) methodology was applied to find optimum flow rate (600 cm h-1) and column load (8XCV) in packed bed columns. A transfer from 1 to 30 and finally to 125 ml column (radial flow) verified the scalability of the capture process; dynamic binding capacity remained at 12 mg protein ml-1 resin. In addition radial flow columns reduced column cycle by 20%. Conclusion: Predictive modeling was successful in finding best protein capture conditions. A model for potato protein adsorption onto the resin is proposed where the relatively smaller protease inhibitor proteins bind strongly through their higher charge density, less sensitive to overload and flow rate. The larger patatins show random charge distribution, binding preferentially to the resin surface, and thus are more sensitive to displacement in secondary layers.
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Strætkvern, Knut Olav
(2009).
Slik lages influensavaksinen.
Hamar arbeiderblad.
Show summary
Slik lages influensvaksinen Å lage vaksiner har kommet langt siden Edward Jenner (1749-1823) gjorde sine forsøk med sårpuss for å immunisere mot kopper for 200 år siden. Louis Pasteur (1822-95) laget en vaksine mot rabies med svekkede virus som var dyrket i ryggmargen hos kaniner. Dagens influensavaksine består av inaktiverte viruspartikler som skal gi oss immunitet, men vaksinen har overraskende nok blitt laget på samme måte i over 50 år, nemlig i hønseegg. Ikke de vanlige eggene vi spiser til frokost, men i befruktede egg der kyllingfosteret utsettes for et massivt virusangrep. Virus kan ikke formere seg på egenhånd, de har arbeidstegningene men mangler verktøy og materialer. De må innta levende celler og særlig celler som reagerer på dem. Et kyllingfoster er derfor et godt voksested. Den tekniske prosessen fram til influensavaksinen er klar på hetteglass eller i sprøyte er både langvarig og omstendelig. De tekniske stegene i framstillingen går i etapper. Ofte er den første pandemibølgen på retur innen en virksom vaksine er klar.
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Løkra, Sissel & Strætkvern, Knut Olav
(2008).
Potato protein isolation by expanded bed adsorption and ultrafiltration.
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The economically viable recovery of waste protein from processing streams for use in developing valuable food products has focused interest on the use of gentle bioprocessing techniques. The objective of this study was to explore how expanded bed adsorption (EBA) and ultrafiltration (UF) can be used to upgrade protein from industrial potato juice (PJ), a by-product otherwise used as feed supplement. EBA-processing on mixed-mode ligands (3.5 gcm-1) in combination with gentle drying was used to obtain potato protein isolates that displayed improved technical functionality [Claussen et al. (2007), Drying Technology, 25:1101-1108; Løkra et al. (2008), LWT/Food Science & Technology, 41: in press]. In pilot scale EBA experiments (17 L resin, 20x200 cm, 400-800 cmh-1), variations in adsorption characteristics were observed for total protein capture from PJ. From breakthrough curves, analysis of the two major components, patatin (42/80 kDa) and the 20-22 kDa protease inhibitors (PI), showed significantly different binding. While a fraction of patatin tends to form homo-oligomeric aggregates escaping adsorption, the native dimeric patatin competes with the PI fraction for binding. Patatin aggregates were studied (HP-SEC) under both native and denaturing conditions, and as covalent aggregates, in order to explain the overall protein adsorption on the mixed-modal ligand. The influence of phenolic compounds, which add to the complexity of PJ, was also investigated in controlled experiments. However, steric hindrance from aggregates appears to be the major mechanism determining differentiated protein capture between native and aggregated patatin, and the PIs. Membrane separation of proteins is a well-established method in bioprocessing. A bench-scale comparison of UF (10 kDa PES, 0.19 m2) and EBA (300 ml resin, 5x65 cm, 400-700 cmh-1) on the same PJ material was carried out. UF operated in batch concentration/diafiltration mode gave a protein composition comparable to EBA. However, the EBA processing was superior to UF in separating phenolic pigments from the concentrated protein, and also concerning protein solubility. Although bioprocessing by UF or EBA is optional in the high-volume recovery of industrial protein, separation on mixed-mode ligands can produce defined fractions with improved qualities relevant to functionality in foods.
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Strætkvern, Knut Olav
(2008).
Bioteknologi på Hedemarken - hvorfor? Min Y-manns slekt, farskap hos storfe og nyttige potetproteiner.
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Strætkvern, Knut Olav
(2008).
Hvordan tenke forskning: bruk av modellsystemer og forsøksdesign Faktorielt forsøksdesign på to nivåer.
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I naturvitenskaplig forskning søker vi svar på spørsmål gjennom eksperimentell metode. Forutsetningen for å finne klare svar på spørsmålene vi stiller er at vi først lager oss et godt modellsystem, så finneut hvilke faktorer som kan påvirke systemet, og deretter spørre "hva skjer hvis...?". Gjennom eksperimenter forandrer vi størrelsen eller nivået av de ulike faktorene på en systematisk måte. Et begrenset antall forsøk kan utføres ved å bruke faktorielt forsøksdesign. Antall forsøk er 2^n, der n = antall faktorer som testet på to nivåer. Tre faktoere eller variabler gir 2^3 = 8 forsøk. Prinisippet belyses med å vise et konkret demonstrasjonsforsøk; immobilisert gjær i alginat for å lage etanol fra glukose. I en omrørt flaske med kontinuerlig gjennomløp er sukkerkonsentrasjon, kulestørrelse og oppholdstid i flasken viktige faktorer for produktiviteten av etanol. Et forsøksdesign krever altså nøye planlegging og bruk av pålitelige målemetoder for å registrere endringer.
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Strætkvern, Knut Olav
(2007).
Bruk av mikroorganismer til industriformål.
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Presentasjon av aktiviteter innen bioprosessteknologi ved Høgskolen i Hedmark, avd. LUNA. presentasjon for gruppe fra Elverum vgs (3.kl biologi).
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Strætkvern, Knut Olav
(2007).
Bioprosessteknologi.
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Gjesteforelesning om fagområdet bioprosessteknologi, med hovedvekt på renseprosesser for industriell proteiner (eks. potetprotein). Bidrag var del av EVU-kurs i bioteknologi for lærere i VGS (kursnr. 2MOBITE19).
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Strætkvern, Knut Olav
(2007).
Utvinning av funksjonelle proteiner som biprodukt fra potetmelproduksjon 2003-2006. Sluttrapport til Norges forskningsråd.
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Populær vitenskapelig framstilling av prosjektet: Potetproteiner har en velbalansert sammensetning av viktige aminosyrer, og i tillegg er det vist at proteinene har meget gode tekniske egenskaper, på linje med soya og melkeproteiner. Ved utvinning av stivelse fra poteter produseres det store mengder avfallsvann, potetfruktvann, som er en fortynnet løsning av proteiner, salter og cellerester. I dag gjenvinnes proteiner fra stivelsesproduksjonen til dyrefôr. Prosjektets mål har vært å utvikle en prosess for utvinning av en proteinfraksjon av næringsmiddelkvalitet, og undersøke de funksjonelle egenskapene til dette. Prosjektet har brukt en kromatografisk metode -EBA- utviklet for bioprosessteknologi, for å fange opp en renset form av proteinene fra fruktvannet. I motsetning til eksisterende industriell teknologi basert på felling av proteinene med syre og varme, kan denne metoden særskilt trekke ut proteiner på en meget skånsom måte. Proteinene beholder dermed sin tekniske egenskaper, og blir samtidig skilt fra smaksødeleggende stoffer. Det raffinerte proteinproduktet er dermed egnet som ingrediens i næringsmidler. Prosjektet har vist at EBA-metoden kan fungerer i stor skala med et sterkt variabelt råstoff; en pilotskala prosess ble gjennomført over flere måneder i en stivelsesfabrikk, der potetråstoffet varierte. Prosessen er kartlagt og optimalisert. Fra pilotforsøkene ble isolert protein konsentrert videre og tørket. Ulike tørketeknikker ble utprøvd for å finne skånsomme betingelser. Kjemiske og funksjonelle egenskaper for ulike proteinpulver ble undersøkt for å finne ut om gunstige strukturegenskaper ble tatt vare på gjennom prosessen. Lavtemperatur spraytørking ga et produkt med svært tilfredsstillende egenskaper, og dette preparatet ble siden testet i modellproduktene grillpølse, lav-karbohydrat brød og i Thousand Island dressing. Resultatene fra disse forsøkene viste at potetprotein i noen av produktene godt kan erstatte både soya og melkeprotein som funksjonell ingrediens.
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Strætkvern, Knut Olav
(2006).
Fusk og fanteri i forskningen Om overtramp som svekker forskningens omdømme.
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Definisjoner: Scientific misconduct - unnlate å gi kredit til viktige bidragsytere til en oppdagelse. Scientific fraud - utgi forfalskede, manipulerte, plagierte eller fabrikkerte forskningsresultater. Historisk: Darwin, Pasteur, Mendel, Freud. Eksempler fra moderne tid: 1946 Otto Hahn- Lise Meitner; 1953 Watson & Crick, Wilkins- Rosalind Franklin; 1969/93Kjell Kleppe- Kary Mullis; 2005 Hwang Woo-suk; 2006 Jon Sudbø; 1998 " Varsleren" Arpad Pusztai.
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Strætkvern, Knut Olav
(2005).
Superprotein fra potetavfall.
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(POSTER) Et NFR-finansiert forskningsprosjekt for utnyttelse av verdifulle proteiner fra poteten. Mål: Næringsrikt protein fra prosessavfall. Utnyttelse av unike egenskaper hos proteiner. Bioprosess-teknologi i ny sammenheng. Industriell produksjon av stivelse. HOFF Brumunddal 30 000 tonn potet/år. Biprodukt 20 000 m3 potetvann (1% protein). Proteinet isoleres med ekspansjonskromatografi (EBA). EBA-metoden er en unik metode til å ta ut proteinfraksjoner som kan ha spesielle egenskaper i næringsmidler. Skånsom tørking bevarer viktige tekniske egenskaper. Testing av potetprotein som næringsmiddel: Løselighet, emulgering, geling. Ingrediens i modellprodukter: Dressing, pølser, lav-karbobrød. Prosessøkonomi? Markedsmuligheter?
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Strætkvern, Knut Olav; Løkra, Sissel; Olander, Morten Aae & Lihme, Allan
(2005).
Food-grade protein from industrial potato starch effluent recovered by an expanded bed adsorption process.
Journal of Biotechnology.
ISSN 0168-1656.
Show summary
Potato tuber proteins are nutritious and show potential as functional ingredient in food systems. However, the present bulk processing technology can only recover byproduct protein for animal feed use. An expanded bed adsorption (EBA) process for isolating functional food-grade protein from crude potato starch effluent was previously developed. Moderate capture efficiency (20-25%) of the total crude protein was most likely caused by diffusion limitations and aggregated protein, inaccessible for adsorption. We employed the same adsorption ligand attached to agarose-tungsten carbide beads to create stable beds of 2.0-2.7X expansion using flow rates at 400-750 cm h-1. A pilot scale EBA process was run in a commercial processing plant over a three month campaign of starch production from potatoes of mixed variety. Fresh crude effluent (150-300 liter/cycle) was applied to a column (20 cm x 2 m) containing 20 liter of resin. Protein capture by EBA was reliable in operation, producing a refined proteinmaterial, which after dewatering and gentle drying, showed improved functionality over heat-coagulated protein produced at the same plant. Overall productivity increased. However, finding a robust operating window of predictable productivity is challenging since the potato fruit water is complex and deteriorates easily. From breakthrough curves, it is observed that the major bulk protein, patatin, displays non-Langmuir adsorption behavior. This may indicate a range of interactions for different species of the same protein. Chlorogenic acid (CQA), the main polyphenolic substance in potato tuber, causes enzymatic browning and undesirable flavor changes, but polyphenols can also react with protein. Assessing the effects of interacting cell components therfore applies to the bioprocessing of plant material.
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Strætkvern, Knut Olav; Løkra, Sissel; Stenseth, Else-Berit & Frydenlund, Kirsten
(2005).
Expanded bed adsorption (EBA) for producing food protein from potato processing waste Adsorbsjon med ekspansjonskromatografi (EBA) til å produsere matprotein fra potetavfall.
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Potato proteins are very nutritious and possess interesting functionality for food formulations. Obtained from dilute fruit water (1-2%) from potato starch processing, this voluminous protein source has been difficult to upgrade from animal feed quality due to an undesirable content of polyphenolic substances, fiber, cell residue and minerals. Chlorogenic acid, the main polyphenolic substance in potato, causes enzymatic browning and off-taste. Plant phenols are also known to react with protein. In this project, applying an industrial processing effluent to novel and robust adsorption resins in expanded bed columns (EBA) has been developed as a possible large scale method for bulk protein recovery. Major protein fractions adsorbed to a heterofunctional ligand attached to a density-controlled resin, followed by a wash step. Change of pH facilitated desorption of refined protein. On the expanded column, chlorogenic acid separated from the proteins, as well as other crude components. The refined protein product has been analyzed for amino acid composition and esterase activity. In pilot scale trials with 50-150 liter of processing effluent, we have demonstrated that expanded bed adsorption is a scaleable method. However, the complexity of the feedstock offers several challenges for optimizing process productivity and thus cost effectiveness. Whether chlorogenic acid or other constituents of the crude extract interact with proteins to change adsorption characteristics is hypothesized. Assessing the effect of interacting components can assist in predicting chromatographic behavior in EBA-processing.
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Løkra, Sissel; Egelandsdal, Bjørg; Egelandsdal, Bjørg; Vegarud, Gerd; Vegarud, Gerd & Strætkvern, Knut Olav
(2005).
Polyphenolic interactions with potato proteins durig expandedn bed adsorption processing.
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Løkra, Sissel; Vegarud, Gerd; Vegarud, Gerd; Strætkvern, Knut Olav; Egelandsdal, Bjørg & Egelandsdal, Bjørg
(2005).
Polyphenolic interactions with potato proteins during industrial expanded bed adsorption processing.
Journal of Biotechnology.
ISSN 0168-1656.
Show summary
In plant extracts it has been shown that polyphenols have a tendency to react with proteins, either by covalent or non-covalent interactions. These reactions can induce changes in the surface properties of the proteins, and e.g. cause proteins to be insoluble and precipitate at pH-values below their isoelectric point. Potato proteins have a high nutritional quality and show interesting functional properties in food systems. Moreover, chlorogenic acid (CA) and caffeic acid constitute about 90% of the total polyphenol content of potato tuber. We have experienced expanded bed adsorption (EBA) chromatography to be a method well suited for recovering industrial proteins from potato starch effluent. The process separates proteins from polyphenolic pigments, fiber and minerals. During the adsorption step, patatin, the major potato tuber protein shows complex binding kinetics demonstrated by breakthrough curves. In addition to diffusion limitations in the EBA resin, changes in protein structure and surface properties probably are likely to affect this adsorption behavior. Reactions between CA and patatin might result in a range of interactions for different species of the same protein. This project therefore aims to assess the interactions between CA, patatin and other major tuber protein fractions and how these changes affect the protein capture in EBA. Changes in size and charge are screened in 2-D electrophoresis and analyzed further. Samples of different protein fractions are taken from breakthrough curves and dynamic binding capacity experiments in model systems with real feedstock.
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Strætkvern, Knut Olav; Olander, Morten Aae & Lihme, Allan
(2002).
Expanded bed adsorption of total soluble proteins from crude feedstock: A pilot-scale study with potato fruit juice.
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(Abstr. no. P75)Stabilized fluidized chromatography beds, or expanded bed adsorption (EBA), is now established in the biotech industry as a first step unit operation in downstream processing of proteins. In the bioprocessing of waste streams in the food industry, EBA is a potentially cost-effective method to utilize diluted proteins of functional or biological value. We have studied an EBA process at pilot scale to capture potato tuber proteins from the processing effluent of starch milling at Hoff Norske Potetindustrier BA. Of the crude protein content of potato processing effluent (10-15 g/l), about two-thirds are soluble, while the aggregated protein fraction is inaccessible to adsorption. Using a mixed mode (heterofunctional) adsorption ligand on density-controlled agarose beads, total soluble proteins were retained as the crude feed passed upward in the expanded column bed. The process was optimized in a 5-cm column (700 ml gel), and transferred to a pilot scale column (20cm Æ, 17 liter). The column cycle was run in expanded mode (H/H0 = 1.6) in all steps, keeping a constant bed height (95-100cm). Different feed loads (30-135 liters) of crude effluents were tested, and the column runs analyzed for protein capture efficiency. As a marker of structural integrity of the captured protein, the fatty acid esterase activity of patatin was employed. The EBA process captured 80-85% of the total soluble protein, while patatin recovery in the product pool was 70-75%, collected in 1.5 column volumes. In repeated runs, a milky white, native protein product resulted, separated from dark-colored phenolic components and aggregates.
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Kommisrud, Elisabeth; Fuglestveit, Ragnhild; Mathisen, Lene; Skinstad, Ingvild J K & Strætkvern, Knut Olav
(2002).
Microbiological examination of bovine semen during processing and effect of different duration of antibiotic exposure.
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Semen may contain bacteria from the prepuce, the environment, equipment or from human handling. Semen processing should, however, guarantee frozen semen from AI-bulls to be free from both specific and non-specific opportunistic bacteria. Important measures to achieve this objective are strict hygiene during collection and processing, together with addition of antibiotics (AB) to the semen. The aim of the present study was to determine the total number of bacteria in neat bull semen, extended/cooled and frozen/thawed semen. Semen extenders were examined with regard to microbiological contamination and for the effect of duration of AB* exposure. Two pooled ejaculates from 20 Norwegian Cattle AI-bulls were included in the study. Samples for microbiological examination were collected from neat semen, extended/cooled semen and frozen/thawed semen. Prior to inoculation on agar spreadplates, samples were diluted to a titre according to preliminary studies. Total bacterial counts (TC), coliforms (CF) and termostable coliforms (TCF) from neat and frozen/thawed semen were estimated on Luria-Bertani (LB) medium and Brilliant Green Bile (BGB). In addition, the frozen/thawed semen was inoculated on LB supplemented with AB to examine the presence of AB resistant bacteria. Extended/cooled semen was examined for TC only. Semen extenders with and without AB stored for one or three days were investigated for microbiological contamination, including TC, AB-resistant bacteria, CF, TCF and fungi. Fungiform growth was examined on Sabouraud Agar. The effect of AB at 35°C was examined by inoculating the extender with E. coli, P. aeruginosa and S. aureus at a titre corresponding to the median TC in neat semen, in addition to lower titres. Samples were spread on LB-medium after 0, 10, 15, 20, 30 and 45 min incubation. Bacteria were found in neat semen from 19 of the bulls, coliforms from 4 and thermostable coliforms in only one (Table 1). No bacterial growth was observed in extended/cooled, frozen/thawed semenor from extender containing AB. In extender without AB, significant bacterial growth was observed, but no growth of AB-resistant or coliform bacteria was detected. In AB-containing extender inoculated with bacteria, bacterial growth was found on samples collected 0, 10, 15 and 20 min after inoculation, but not after 30 and 45 min incubation. The bacterial growth persisted for a longer period when the contaminating dose was increased. Table 1. Bacterial count in neat semen from 20 Norwegian Cattlebulls. Number of bacteria per ml Examination No of bulls pos. Range Average ± SD Median Total bacteria count (TC) 19 0-2.5*105 3.5*104±5.3*104 7.2*103 Coliforms (CF) 4 0-6.6*102 1.0*102±2.2*102 0 Thermostable col. (TCF) 1 0-2.8*103 - 0 Key words: bull semen, bacteria, quality control, antibiotics * Antibiotics used in the study: penicillin/ streptomycin
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Strætkvern, Knut Olav; Olander, Morten Aae & Lihme, Allan
(2002).
EBA processing of potato fruit water on mixed mode adsorbent for functional protein recovery: A difficult separation task made possible.
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Potato starch processing produces large volumes of fruit water (PFW), a crude, protein-rich effluent, that causes costly treatment steps before disposal. Potato proteins are both nutritious, low allergenic and offer a range of interesting functionalities in food systems, provided they can be recovered without denaturation. However, no economical process is yet available to extract palatable and native potato proteins for human consumption. The soluble protein fraction has to be separated from coarse particulate matter, plant fibers, phenolic pigments and salts that make up the complexity of crude PFW. In this study we evaluate Expanded Bed Adsorption as a potential industrial-scale processing method for this demanding separation task. We developed a recovery process and tested it in an all-expanded pilot-scale EBA system using a real industrial feedstock. The major protein fractions were captured on a mixed mode (heterofunctional) ligand on glass-agarose beads. Crude PFW was collected fresh several times during the milling campaign from a local potato starch mill, adjusted to a suitable pH, and extracted for protein on the column. The process cycle was optimized in a 5-cm column (700 ml adsorbent, H0 33 cm), and transferred to the pilot-scale column (20 cm Æ, 17 liter, H0 60 cm). The column cycle was run in expanded mode (H/H0 = 1.6) in all steps, keeping a constant bed height. Varying feed loads (30-135 liter) of crude PFW were tested, and the column runs analyzed for protein capture efficiency. Protein was desorbed with an alkaline pH step and collected in 1.5 column volumes in expanded mode. Tap water proved sufficient for column re-equilibration and wash steps. As a marker for structural integrity of the captured proteins, the fattyacid esterase activity of patatin was monitored 1. Protein and enzyme data were applied to mass balance and recovery calculations. Of the crude protein content of potato processing effluent (8-15 g/l), about two-thirds are soluble, while the aggregated protein fraction is yet inaccessible to adsorption. Although the protein capture efficiency was moderate (20-25 %), binding characteristics of the mixed mode adsorbent suggest that feed loads of 8-10 times the gel volume are possible. A saturated EBA-column is able to concentrate the patatin activity 3-fold. Over the range of feed volumes and batch variability we experienced with the industrial feedstock, the process proved robust and reliable. In repeated runs, a milky white, native protein concentrate (2%) resulted, effectively separated from dark-colored phenols and aggregates. Gentle dewatering in subsequent steps gives a protein preparation that can be used as a food ingredient and for novel food applications. 1 Strætkvern KO, Schwarz JG, Wiesenborn DP, Zafirakos E, & Lihme A (1999). Expanded bed adsorption for recovery of patatin from crude potato juice. Bioseparation 7: 333-345.
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Strætkvern, Knut Olav; Zafirakos, Elias & Oleander, Morten Aae
(2001).
Capture of functional proteins from potato processing effluents : a model system for plant protein recovery using expanded bed adsorption.
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Strætkvern, Knut Olav; Wiesenborn, Dennis P; Zafirakos, Elias & Lihme, Allan
(2001).
Capture of patatin from potato fruit juice using mixed mode EBA matric es.
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We have employed crude potato fruit juice (PFJ) as a model feedstock to isolate patatin as the target protein using an expanded bed adsorp tion (E process to investigate bioprocessing of proteins from plant b iomass. Patatin is the major storage protein of potato tubers, and is released in ample amounts (20-40% of soluble protein) in the fruit j uice during starch milling. The protein possesses lipid acyl esterase activity, which facilitates easy enrichment monitoring during purifi cation. The patatins, heterogeneous by charge, are glycoproteins (44 kDa), and dimerize to obtain the active enzyme form. Crude PFJ is a p rocess waste effluent rich in proteins, minerals, and organic acids, however, the juice is unstable due to the oxidation of plant phenolic s which rapidly discolor the juice. To avoid dilution of the high-con ductivity
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Strætkvern, Knut Olav
(2000).
Bioteknologi ved Høgskolen i Hedmark. Debattinnlegg. "Perspektiver i moderne bioteknologi- nye muligheter for Innlandet.".
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Strætkvern, Knut Olav
(2000).
Bioteknologi - nye muligheter for Hedmark ? Horisont 21: scenarier ved et nytt årstusen. Konferanse i regi av Hedmark Fylkeskommune og Sparebanken Hedmark.
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Strætkvern, Knut Olav
(2000).
Hva er genmodifisering ? Hva gjør det med maten vår ?
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Strætkvern, Knut Olav; Zafirakos, Elias & Aae Olander, Morten
(2000).
Direct recovery of target and total protein from crude feedstock with mixed mode adsorbents in expanded beds.
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Expanded bed adsorption (EBA) bioprocessing of potato processing effluents, opposite to traditional harsh bulk precipitation methods retain the structural integrity of the tuber proteins. Whole or fractionated potato tuber protein, with improved functional qualities could prove useful in food systems and other biological applications. Employing high-density agarose-glass adsorbent particles in a fluidized bed configuration, expanded beds allow the crude feedstock to be fed directly to the column in a uniform upward flow. The adsorbent particles are coupled with a heterofunctional (mixed mode) ligand developed by UpFront Chromatography AS. The ligands consist of small organic molecules containing both hydrophobic and ionic substituents, customized to capture the target proteins. Protein binding is strongly pH dependent, but insensitive to high ionic strength. We describe a scaleable approach for native protein recovery on customized mixed mode adsorbents. Following a pH adjustment, the crude effluent (15-20 gl-1 protein) from potato starch milling was applied to a 5-cm expanded
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Strætkvern, Knut Olav & Føllesdal, Liv Marthe Stigen
(1998).
Fractionation of potato proteins by ultrafiltration.
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Potato starch processing generates large volumes of process juice (5% dry weight) with a high content (50%) of water soluble proteins. Pot ato prote consist of 3-4 distinct molecular weight fractions of 5-100 kDa, the major fractions beeing Kunitz-type protease inhibitor compo nents (22kDa) and the glycoprotein patatin (44 kDa). Mainly considere d a waste stream of low economical value, potato juice concentrates a re now seeking new applications. Based on gel permeation profiles of crude process juice, we have performed preliminary fractionation and concentration experiments by ultrafiltration in an open channel filte r unit (Bioengineering). Selective retenetion of all proteins above 1 5 kDa was attained with membrane of 30kDa MWCO, whereas a membrane of 100kDa MWCO leaked the major protein fractions to the permeate. Char acteristics of batch processes are presented.
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Strætkvern, Knut Olav; Lund, Tina & Rønning, Rolf S.
(1998).
Patatin - the plentiful potato protein : Some molecular characteristics and enzymology of the lipid acyl hydrolase.
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We have purified patatin, the lipid acyl hydrolase of potato tubers ( cv. Laila), to homogeneity. Patatin is an fatty acid esterase hydroly sing a va of mono- and diacyl lipids. Besides its function as storage protein, patatin has potency as an insecticide, possibly due to its release of cytotoxic fatty acids. We have studied patatin in relation to its large scale recovery from potato processing waste and potenti al technological applications. Our report adresses some enzymological aspects as well as its protein chemistry. N-terminal analysis of the first 22 residues confirmed its identity as it almost have complete homolgy to other known patatin sequences. Isoelectric focusing of the homogenous 44 kDa protein revealed 6-10 isozymes in the range 4,5-5, 1, as judged by paralell zymogram analysis. Charge heterogenity of pa tains is thought of different gene products. The native enzyme protei n was also analysed by gelfiltration, appearing as a possible multime ric aggregate form. The temperature stability at pH 8,2 showed rapid inactivation at 60ºC (t=1,7 min), whereas prolonged stability was obs erved at 50ºC (192 min) and 40ºC (>48 h). Rapid deactivation is consi stent with the collapse of
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Strætkvern, Knut Olav; Blystad, Frøydis D. & Bøhler, Randi A.
(1998).
Deproteinised potato fruit juice as a complete medium for growth of Lactobacillus plantarum NCDO 1752.
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Potato starch mills generate waste effluents rich in minerals, free a mino acids and proteins, and non-protein N-substances, essential for microbial growth. From a potato processing plant, two aseptic juice f ractions were obtained after deproteinisation; potato protein liquo r (PPL) and potato ultrafiltration permeate (PUP). Both media were te st ed as complete growth media for Lactobacillus plantarum, strain NC DO 1752, and were compared to the standard Man-Rogosa-Sharp media for la ctobacilli. Optimal growth conditions on PPL and PUP were establi shed in a microtiter screening assay (300 ml), verified in shaking b ottle s (100 ml), and finally transferred to 2 liter CSTR-fermentatio ns und er pH-stat conditions. On pure PPL and PUP, with 2% dextrose a nd at 3 7oC, pH 6.5, the growth rate, lactic acid production and the total ce ll mass yield, were comparable on all levels of cultivation. However, fermentable sugars present in the potato juices, alone pro vided enou gh energy for growth and lactate production, typically 20- 40 % of the control. Growth yields on 2 % dextrose in PPL and PUP fer mentations, were 30-40 % higher than the MRS-control, but the specifi c growth rat es were 80% an
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Strætkvern, Knut Olav; Lund, Tina; Mathisen, Tone & Rønning, Rolf S.
(1998).
Recovery by adsorbtion of esterase active patatins from potato processing waste.
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We have designed an ion exchange adsorbtion process which concentrate s and fractionates the major soluble proteins from potato waste, the patatins. patatins are anionic isoenzymes (44 kDa), having a lipid ac yl hydrolase (LAH) activity, which is useful for monitoring protein e nrichment. The raw potato juice (36 g protein l-1) collected from a c onventional starch manufacturing process, was conditioned with respec t to the protein concentration, pH and conductivity prior to capture on Q Sepharose Big Beads in an axial flow, 40 ml lab scale column. Pa tatin was selectively concentrated with a factor of five, at 80-98 % recovery, and after freeze drying, 81% of the initial LAH-activity re mained. Analysis of the contaminating protease inhibitors, currently a major hindrance for food applications of the raw protein fraction, demonstrated a 43-57% reduction compared to the raw feed. The column cycle was succesfully scaled up employing a 250 ml radial flow column . The dynamic binding capacity of the adsorption process was sensitiv e to the linear flow rate, possibly due to diffusion limitations. How ever, doubling the total protein load to 150 mg ml-1 gel, the enrichm ent factor increased from 2
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Strætkvern, Knut Olav
(1998).
Bioteknologi og poteten : ny teknologi under skallet.
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Joshi, Mukund; Ahmad, Rafi & Strætkvern, Knut Olav
(2021).
Testing of different conditions to accelerate culturing and
potentially reduce the time of detection of pathogens and
antimicrobial resistance.
HINN.
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Strætkvern, Knut Olav
(1997).
Laboratorium for bioanalyser - Delprosjekt "Analyse av aminosyrer i fôrvarer". Sluttrapport for prosjektperioden 1995-96.
Høgskolen i Innlandet.
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Kvantitativ bestemmelse av essensielle aminosyrer i fôrvarer står sen tralt i dokumentasjonen av fôrets ernæringsverdi. Rask og sikker best emmelse er viktig for å sikre tilfredstillende produkter. Delprosjekt et ble startet som et utviklingsprosjekt for å etablere nødvendig kun nskap og metodikk for å kunne utføre aminosyreanalyser her i regionen , med utgangspunkt i laboratoriemiljøet ved Blæstad, i samarbeid med HIAS. Utvikling av metoder for aminosyrebestemmelse av essensielle am inosyrer i fast og flytende fôr ble utført. Det foreligger standard o perasjonsprosedyrer (SOP) for de fleste prosedyretrinnene som grunnla g for senere akkreditering. Prosjektet har dokumentert anvendelsen av en ny og raskere metode med bruk av mikrobølgeovn for prøveopparbeid ing som vil kunne gi en mer rasjonell analysedrift. Mikrobølgeovn-hyd rolyse ga også overraskende gode data for enkelte sårbare aminosyrer. Prosjektet oppnådde ikke å nå tilfredsstillende analysebetingelser f or alle aminosyrer, slik at det fortsatt er nødvendig med en instrume ntbetinget optimalisering av HPLC-analysene. Prosjektet har vist at d et er teknisk mulig å etablere et analyseopplegg for aminosyrer i fôr varer med de ressurser som
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