M.A. Thesis:

Effect of edible coatings based on native tragacanth gum and psyllium (Plantago ovate) on the shelf life of fruit slices orange variety Thompson

The aim of this research was to study the effect of coating simolteniously with native tragacanth gum and psyllium on the quality of the orange cuts. According to RSM, this experimentation was done with 20 treatments and 6 replication in the central point. In the coating solution tragacanth was used by a ratio of 0.2, 06 and 1 gram in 100 ml of distilled water and psyllium was used by ratios of 0.5, 0.2 and 0.35 gram in 100 ml distilled water used in a fixed amount of 0.1% Tween 80. Uncoated orange cuts were chosen as controls. Coated and uncoated orange cuts were kept under 4 degree centigrade temperature and relative humidity of 75%. Focus feature included weight loss, TTS( Brix), titrable acid, Ph, vitamin C and colorimetric. The results showed that coating caused a reduction in the weight loss and by increasing the amount of tragacanth gum and psyllium orange cuts had less weight loss( 7.85%) . also the results of meaning the amount of vitamin C showed that increasing the amount of tragacanth gum from 0.2 ml in 100 gram(22.69) to 1% (11.48) has caused a decreased in the amount of vitamin C during the storage time. Colorimetric results also showed that orange cuts coated by a higher percentage of tragacanth gum and pysllium have got a higher L* and lower a*and b*. the coating made of 1% tragacanth and 0.35% psyllium showed better results compared to other coating. Finally the coated orange cuts and the uncoated ones( control) were kept under 4 degree centigrade temperature for 15 days and every 5 days weight,TSS,titrable acid,pH, vitamin C, coloer and firmness were measured. Sensory evolution was done at the end of the 15th day. According to the experimentation results, coated sample showed less weight loss and more firmness compared to the controls .also compared to the control, the coated ones got a higher score in the sensory evolution. .

Keywords: Key word: food coating, orange cuts, trgacanth, psyllium, tween 80