Polyoleilla pehmitettyjen perunatärkkelyskalvojen valmistaminen ja karakterisointi

The present study investigated the potato starches and polyols which were used to prepare edible films. The amylose content and the gelatinization properties of various potato starches extracted from different potato cultivars were determined. The amylose content of potato starches varied between 11.9 and 20.1%. Onset temperatures of gelatinization of potato starches in excess water varied independently of the amylose content from 58 to 61°C determined using differential scanning calorimetry (DSC). The crystallinity of selected native starches with low, medium and high amylose content was determined by X-ray diffraction. The relative crystallinity was found to be around 10 13% in selected native potato starches containing 13 17% water. The glass transition temperature, crystallization melting behavior and relaxations of polyols, erythritol, sorbitol and xylitol, were determined using (DSC), dielectric analysis (DEA) and dynamic mechanical analysis (DMA). The glass transition temperatures of xylitol and sorbitol decreased as a result of water plasticization. Anhydrous amorphous erythritol crystallized rapidly. Edible films were obtained from solutions containing gelatinized starch, plasticizer (polyol or binary polyol mixture) and water by casting and evaporating water at 35°C. The present study investigated effects of plasticizer type and content on physical and mechanical properties of edible films stored at various relative water vapor pressures (RVP). The crystallinity of edible films with low, medium and high amylose content was determined by X-ray diffraction and they were found to be practically amorphous. Water sorption and water vapor permeability (WVP) of films was affected by the type and content of plasticizer. Water vapor permeability of films increased with increasing plasticizer content and storage RVP. Generally, Young's modulus and tensile strength decreased with increasing plasticizer and water content with a concurrent increase in elongation at break of films. High contents of xylitol and sorbitol resulted in changes in physical and mechanical properties of films probably due to phase separation and crystallization of xylitol and sorbitol which was not observed when binary polyol mixtures were used as plasticizers. The mechanical properties and the water vapor permeability (WVP) of the films were found to be independent of the amylose content.Korvaamalla tavanomaisia synteettisiä pakkausmateriaaleja biomateriaalikalvoilla voidaan vähentää synteettisiä maatumattomia jätteitä biologisesta kiertokulusta. Biomateriaalikalvoilla voidaan parantaa elintarvikkeiden laatua, turvallisuutta ja säilyvyyttä muodostamalla kuiva- tai tuoretuotteen pinnalle este, jolla vesihöyryn ja kaasujen siirtyminen suojattavaan tuotteeseen tai suojattavasta tuotteesta estetään. Biomateriaalikalvoa voidaan myös käyttää kantajana esim. aromi- tai antimikrobisille yhdisteille, joilla voidaan antaa lisäarvoa elintarvikkeelle tai edesauttaa elintarvikkeen säilyvyyttä ja turvallisuutta. Elintarvikkeiden lisäksi biomateriaalikalvoilla voidaan myös tuoda lisäarvoa kiinteille lääkevalmisteille. Tässä työssä tutkittiin eri perunatärkkelyksien ja polyolien (glyserolin, erytritolin, ksylitolin ja sorbitolin) soveltuvuutta biomateriaalikalvojen valmistamiseen. Eri perunatärkkelyksien amyloosipitoisuudet ja liisteröitymisominaisuudet määritettiin. Amyloosipitoisuudet vaihtelivat 11,9 21,1 %:n välillä. Differentiaalisella skanningkalorimetrilla (DSC) määritetyt liisteröitymisen alkulämpötilat vaihtelivat 58 61 °C:n välillä amyloosipitoisuudesta riippumatta. Valikoiduista eri amyloosipitoisuuden omaavista tärkkelyksistä määritettiin suhteelliset kiteisyydet, jotka olivat 10 13 %:n. Vedettömien ja vettä sisältävien polyolien faasi- ja tilamuutoksia tutkittiin termoanalyyttisillä menetelmillä: DSC:lla, dielektrisellä analyysillä (DEA) ja dynaamismekaanisella analyysillä (DMA). Polyolien lasisiirtymälämpötila, jossa polyoli muuttuu kovasta ja hauraasta pehmeäksi ja virtaavaksi, aleni veden vaikutuksesta. Biomateriaalikalvot valmistettiin tärkkelys-polyoli-vesisuspensiosta, jota kuumennettiin tärkkelyksen liisteröimiseksi ja lopuksi valamalla ja haihduttamalla vesi 35 °C:n lämpötilassa. Tässä työssä tutkittiin pehmittimen, polyolin tai kahden polyolin seoksen, pitoisuuden vaikutusta tärkkelyskalvojen ominaisuuksiin. Erilaisissa ilman suhteellisissa kosteuksissa tasapainotettujen kalvojen fysikaalis-kemiallisia ominaisuuksia, kuten veden sorptiota, vesihöyrynläpäisevyyttä ja mekaanisia ominaisuuksia, tutkittiin. Valikoiduista eri amyloosipitoisuuden omaavista tärkkelyksistä valmistettujen kalvojen suhteellisten kiteisyyksien havaittiin olevan 0 4 %. Kalvojen kiteisyydellä ei havaittu olevan selvää vaikutusta kalvojen fysikaalis-kemiallisiin ominaisuuksiin. Kalvoissa käytetyllä pehmittimillä ja pehmitinpitoisuuksilla oli vaikutusta veden sorptioon ja vesihöyrynläpäisevyyteen. Pehmitinpitoisuuden ja ilman suhteellisen kosteuden kasvaessa kalvon veden sorptio ja vesihöyrynläpäisevyys kasvoivat. Kalvojen mekaanisia ominaisuuksia kuvaavat Youngin moduuli ja vetolujuus pienenivät sekä venymä katkeamishetkellä kalvoi pehmitinpitoisuuden ja ilman suhteellisen kosteuden kasvaessa. Käytettäessä pehmittimenä ksylitolia tai sorbitolia pehmittimen havaittiin kiteytyvän kalvossa, minkä seurauksena polyolin pehmittävä vaikutus pieneni. Tämän seurauksena kalvojen Youngin moduuli ja vetolujuus kasvoivat sekä venyvyys katkeamishetkellä pieneni. Pehmittimen kiteytyminen voitiin ehkäistä käyttämällä kalvossa kahden polyolin seosta. Tässä tutkimuksessa saatua tietoa eri pehmittimien ja niiden pitoisuuksien vaikutuksesta perunatärkkelyskalvojen fysikaalis-kemiallisiin ominaisuuksiin tarvitaan, kun arvioidaan kalvojen soveltuvuutta elintarvike- ja lääkesovelluksiin. Tässä tutkimuksessa tutkittujen kalvojen ehdotetaan soveltuvan matalan kosteuspitoisuuden omaaville elintarvike- ja lääkevalmisteille

Talc reinforcement of polylactide and biodegradable polyester blends via injection-molding and pilot-scale film extrusion

The authors wish to thank Arctic Biomaterials Oy for the compounding of the masterbatches, the assistance of Sai Li with the preparation of injection-molded specimens, and Laura Koskinen for the help with the figures. The research group of Paper Converting and Packaging Technology at Tampere University was gratefully acknowledged for conducting the extrusion coating trials and oxygen barrier measurements.As a renewable and biodegradable polymer, polylactide (PLA) has taken a foothold in the packaging industry. However, the thermomechanical and barrier properties of PLA-based films need to be improved to facilitate a wider adoption. To address this challenge, we examined the effect of talc reinforcement in composites based on PLA and a biodegradable polyester. Masterbatches of the polymers and talc were produced by melt compounding and processed by either injection-molding or film extrusion in a pilot-scale unit operating at 60–80 m/min. The effect of talc was investigated in relation to the morphological, thermal, mechanical, and barrier properties of the composites. Based on SEM-imaging, talc was found to increase the miscibility of PLA and the polyester while acting as a nucleating agent that improved PLA crystallinity. While this effect did not track with an increased mechanical strength, the composites with 3–4 wt% talc displayed a significantly higher barrier to water vapor. Compared to the neat polymer films, a reduction of water vapor transmission rate, by ~34–37%, was observed at 23°C/50% RH. Meanwhile, the systems loaded with 1 wt% talc showed a reduction in oxygen transmission rates, by up to 34%. Our results highlight the challenges and prospects of commercial PLA-based blends filled with talc from films extruded in pilot-scale units.Peer reviewe

Mineral-filled biopolyester coatings for paperboard packaging materials: Barrier, sealability, convertability and biodegradability properties

The authors wish to thank Arctic Biomaterials Oy for the compounding of the masterbatches. Metsä Board research laboratory technicians are also acknowledged for assistance in laboratory analyses along the research group of Paper Converting and Packaging Technology at Tampere University, for the extrusion coating trial, OTR analysis and hot air sealing tests. Finally, Kruunukartonki – Länsipahvi Oy is thanked for assistance with the cup forming trials, and Itene for the biodegradability tests.Changing trends in packaging materials has been driven by increasing environmental awareness as well as legislation. In this context, paperboard-based packaging have become increasingly popular due to its bio-based origin, potential biodegradability and physical properties. However, conventional systems lack behind in barrier performance and heat sealability. Hence, the addition of functional layers have been considered as alternative solutions to this challenge. Here we propose a biodegradable PLA-based polymer coating filled with minerals (0-10 wt% loading), namely, talc, kaolin and calcium carbonate, all of which were used in surface application on uncoated folding box board. For this purpose, we used a pilot-scale extrusion unit that produced materials that were tested for key properties. We found that the presence of filler in the PLA layer improved both water vapor (up to 16 %) and oxygen (up to 56 %) barrier properties. Moreover, the main effect of the fillers was observed in heat sealability, which was improved via adhesion at low temperatures, resulting in full fiber tear. Cup forming was less effected by filler loading in the PLA coating while repulping tests indicated the presence of large flakes of the polymer coating in 1 %-consistency slurries. Finally, biodegradability was slightly delayed in filler-containing samples (biodegradation within 10-60 days), most likely due to the nucleating effect of the fillers. Nevertheless, all the samples can be classified as biodegradable. Overall, our results represent a step forward in scale-up adoption of PLA-based coatings most useful in the development of packaging materials.Peer reviewe

Effects of talc, kaolin and calcium carbonate as fillers in biopolymer packaging materials

We wish to thank the assistance of Sai Li with the sample preparation, Päivi Kauppinen with the SEM imaging, Tuula Rautiainen with the WVTR analyzes and Säde Mäki (Tampere University) for conducting the oxygen barrier measurements. Research funding: None declared.We compared the performance of bio-based and biodegradable polymers for packaging applications. Cost-effective inorganic fillers (talc, kaolin and calcium carbonate) were first melt-compounded with polylactic acid (PLA), poly(butylene adipate-co-terephthalate) (PBAT) and poly(hydroxy butyrate-co-valerate) (PHBV). Following this, injection- and compression-molded specimens were produced to test the effect of filler loading (0-30 wt%) in relation to the morphological, thermal, mechanical and barrier properties of the composites. All the fillers were homogeneously dispersed in the polymer matrices and suitable polymer-filler adhesion was observed for talc and kaolin. The elastic modulus increased at the expense of a reduced tensile and elongation. The most significant improvements in water vapor and oxygen barrier properties were achieved with talc in PLA, PBAT and PHBV films. Overall, the results point to the promise of the introduced compositions for food packaging materials.Peer reviewe

Experiences of Kraft Lignin Functionalization by Enzymatic and Chemical Oxidation

Linear hydrophilic derivatives are expected to soften lignin and improve its utilization in composite applications. Oxidation by means of laccase in the presence of oxygen was employed in an attempt to functionalize commercial kraft lignin by vanillic acid-PEG ester and ether derivatives. Thielavia arenaria and Melanocarpus albomyces laccases at pH 6 and 8 were used. According to O2 consumption and the increase in molar mass, the tested laccases were active toward the lignin and the vanillic acid derivatives and also formed corresponding phenoxyl radicals. However, homogenous polymerization instead of cross-coupling and functionalization took place. As an alternative, lignin functionalization by the ester derivative by chemical oxidation under alkali-O2 conditions was also tested. Efficient lignin polymerization was observed. However, functionalization was not detected. Interestingly, a clear decrease in lignin glass transition temperature was obtained by an isolation procedure that included freeze-drying. This suggests that functionalization may not be necessary to induce the desired softening effect

Kabul Times. (Kabul, Afghanistan), 1977-01-25

Kabul Times. (Kabul, Afghanistan), 1977-01-25; Volume 15; Number 25