some physicochemical and rheological properties of zedo (farsi) gum exudates from amygdalus scoparia

Background and objectives: zedo gum is exuded in three colours (white, yellow, and red) from amygdalus coparia. it is used in both food and non-food industries, as well as in traditional medicine. this study aimed to etermine the physicochemical and rheological properties of zedo gum. materials and methods: zedo gum was collected in sirjan and classified into three groups, based on colour samples w, y, and r). their soluble parts were separated by centrifuging the dispersions and freeze-drying the upernatants. surface tension was determined using du nouy ring method and nmr spectroscopy was carried out using a varian inova-500 mhz spectrometer. gel permeation chromatography was used for determining molecular weight and rheological data were obtained with a physica mcr 301 rheometer. results: surface tension decreased as the concentration decreased, except for sample r that had a maximum oint at 1 %. the molecular weight of sample w was the highest, while its dispersity was the lowest. nmr pectroscopy indicated that ara residues variously were linked to α-araf residues, and gal residues were etermined as terminal α-gal residues. intrinsic viscosity values for samples w, y, and r were 7.14±0.13, .45±0.11 and 5.40±0.15dl/gr, respectively. rheological results showed that viscosity was inversely roportional to temperature and directly to concentration. conclusions: as three samples of zedo gum had different characteristics, colour can be a good tool in trade.