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    Composition, morphology and pasting properties of Orchis anatolica tuber gum
    (ELSEVIER SCI LTD, 2017) Bulut-Solak, Birsen; Alonso-Miravalles, Loreto; O'Mahony, James A.
    Orchis anatolica (O. anatolica) tuber is commonly used in the production of Salep gum or O. anatolica tuber gum (OaG) for use as a thickener, flavouring agent, gelling agent, film former and emulsifier in the food industry. The aim of this study was to investigate the chemical composition, physical, morphological and pasting properties of OaG. Physical and morphological analyses, and pasting properties of OaG were analysed using static light scattering, scanning electron microscopy, light microscopy and rotational rheometry, respectively. Volume-weighted mean particle diameter (D [4,3]) value of OaG was 180 +/- 1.25 mm. OaG was composed mainly of starch (41.6%), dietary fiber (32.3%) and glucomannan (18.5%). The powder of OaG had irregular shaped particles with smooth surfaces and round edges. After pasting treatment, the initial and final viscosity values of the OaG dispersions at a concentration of 0.5% OaG were 33.7 +/- 0.24 and 34.3 +/- 0.45 mPa. s, whereas, the corresponding values at a concentration of 2.5% OaG were 1193 +/- 92.0 and 1437 +/- 83.3 mPa. s, respectively. The glucomannan and dietary fiber components and their possible interactions with starch, in OaG appear to have influenced the peak temperature and viscosity on pasting, due to limitation of the leaching of amylose and amylopectin from starch granules. Therefore, O. anatolica tuber gum, a complex biopolymer, can provide interesting and unique functionality to the food industry in the development of novel food structures. (C) 2016 Elsevier Ltd. All rights reserved.
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    Rheological and microstructural properties of rennet-induced milk protein gels formed with Orchis anatolica gum
    (ELSEVIER SCI LTD, 2015) Bulut-Solak, Birsen; O'Mahony, James A.
    The effects of Orchis anatolica gum (OaG) on the structural and rheological properties of rennet-induced milk protein gels were investigated. OaG, at 0-0.15%, was added to reconstituted skim milk solutions of identical pH (6.60) and protein content (3.5%). Analyses included dynamic low amplitude oscillatory rheology, forced syneresis (FS) and confocal laser scanning microscopy (CLSM). Addition of 0.10% OaG to reconstituted skim milk solutions decreased the gelation time from 20.2 to 13.4 min, increased the gel firmness from 12.8 to 22.2 Pa and increased FS from 24.4 to 40.7% at 60 min. OaG affected formation of milk protein gel structure by increasing viscosity of the aqueous phase and inducing phase separation, with the balance of these effects dependant on the concentration of OaG. These insights on thermodynamic compatibility between OaG and milk proteins could provide unique functional properties to milk protein gels and facilitate innovation in cheese product development. (C) 2015 Elsevier Ltd. All rights reserved.