Film formation and some structural features of hem

Authors: Tomoko Shimokawa Eiji Togawa Koichi Kakegawa Atsushi Kato Noriko Hayashi

Publish Date: 2014/10/29

Volume: 61, Issue: 1, Pages: 53-59

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Abstract

Biodegradable translucent and transparent films were prepared from the hemicellulose fractions of Pinus densiflora leaves without using substantial amounts of additives These fractions were isolated by alkaline extraction using 10  sodium hydroxide after delignification by sodium chlorite and precipitated with 80  ethanol The watersoluble fraction of the P densiflora hemicellulose was mainly composed of arabino4Omethylglucuronoxylan according to a sugar analysis and NMR spectroscopy The waterinsoluble fraction contained more mannanrelated polysaccharide than watersoluble fraction Whole hemicellulose and the waterinsoluble fraction formed stable films when they were dispersed in water cast into petri dishes without additives and dried The watersoluble fraction formed the most transparent film and it required a 1  w/w of polysaccharide lecithin additive while it was peeling off from the dish to be used as a selfsupporting film The 10–12 μm thick films had an average tensile strength of 36–43 MPa and 21–25  elongation at break In the long wavelength the light transmission was high in the order of watersoluble whole hemicellulose and waterinsoluble fraction P densiflora leaves have a history of being edible thus the leaves of this tree can produce a useful and edible hemicellulose filmThe needlelike leaves of Pinus densiflora Japanese red pine akamatsu have been used since a long time for preparing folk medicine These leaves have been historically used as a crude plant drug dating back to the Edo era in Japan and its description can even be found from earlier ages in China 1 The dried powder of whole P densiflora leaves is commercially available as tea There are many reports on the ingredients 1 2 3 and biological functions 4 5 of the essential oil and volatile fraction of P densiflora leaves however only limited information is available on its hemicellulose componentRecently biodegradable and/or edible films produced from plantbased polysaccharides such as hemicelluloses and celluloses have attracted attention as replacements for petroleumbased films According to a report by Mikkonen and Tenkanen 6 xylans and mannans obtained from agriculture and forest industries could be a source of sustainable packaging materials in the future The properties of xylan and mannanbased films are suitable for foodpackaging although in some cases these films require components such as plasticizers to maintain selfsupporting forms 7 8 9 The property of produced films from hemicellulose has been studied for decades and their production from the wood meal of P densiflora has been previously reported from the standpoint of sorption of water vapor 10Some edible films produced from polysaccharides are widely used in the food industry for example oblate pullulan and agar Films from hemicelluloses may also be used in the food industry Although they are not very common as edible material P densiflora leaves are a sustainable bioresource that can be obtained from established forests To facilitate the future utilization of hemicellulosebased films derived from these leaves as edible films we report some of their structural characteristics and mechanical propertiesDry powder of P densiflora leaves for a beverage was purchased It was prepared from P densiflora leaves collected domestically and was washed dried and pulverized Beech xylan and birch xylan were obtained from Sigma and Fluka respectively Dextran standards with molecular weights of 1000–410000 were purchased from Sigma The dextran standard with a molecular weight of 668000 was obtained from polymer standards service Lecithin from soybean was obtained from Wako and 4Omethylglucronic acid MeGlcUA prepared from beech xylan was provided by Dr S Yoshida University of Tsukuba a single spot on TLC analysis verified its purityTo determine the acidinsoluble lignin content of P densiflora leaves the powder was boiled in an 80  ethanol solution for 10 min collected on a G3 fritted glass filter and airdried before acid hydrolysis of the powder using dilute sulfuric acid 11 The ash content was determined and subtracted from the apparent acidinsoluble material to calculate the acidinsoluble lignin content The relative sugar contents of polysaccharides were analyzed after hydrolysis of polysaccharides using 2 M TFA then trimethylsilyl methyl ester glycoside derivatives were detected by GC14A gas–liquid chromatography GLC Shimadzu equipped with a DB1 column 025 mm × 30 m J W Scientific 12 The following seven neutral sugars were analyzed as compositional sugars arabinose Ara fucose Fuc rhamnose Rha xylose Xyl mannose Man galactose Gal and glucose Glc in addition to the following three kinds of acidic oligosaccharides glucuronic acid GlcUA galacturonic acid GalUA and MeGlcUA Methylation analysis of polysaccharides was conducted according to the modified method of Hakomori 13 14 The partially methylated alditol acetates were analyzed by GLCMS JEOL AMII15 using an SP2330 column 025 mm × 30 m Supelco 13CNMR spectra were recorded at 495 °C in D2O on a JEOL α500 spectrometer operating at 12565 MHz Chemical shifts ppm were measured relative to the internal dioxane at 6740 ppm or internal trimethylsilylpropionic acid TSP at 000 ppm The particle size distribution was measured using a laser diffraction spectrometer HELOS/KR along with a dry disperser RODOS/L HELOS RODOS at the Japan Laser Corporation Tokyo Japan

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