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    Öğe
    Seasonal changes in the yield and gel properties of agar extracted from Gelidium latifolium (Rhodophyta)
    (Springer, 2019) Ogretmen, Ozen Yusuf; Kaya, Yalcin
    Gelidium latifolium collected monthly at Sinop Peninsula (Black Sea, Turkey) was studied during a 1-year period. Physical and gelling properties of agar extracted from G. latifolium were investigated. Results showed that agar yield was not significantly affected by seasons and ranged from 32.79 +/- 0.78 to 39.26 +/- 0.37%. Quality parameters such as pH, total ash, acid-insoluble ash, and moisture complied with the international standards and acceptance criteria established for agar. High melting temperature (93.86 +/- 0.27 degrees C) and gelling temperature (47.46 +/- 0.20 degrees C) were obtained in autumn. A relatively high viscosity, gel strength was obtained in autumn and during the second half of the year. Lowest acid-insoluble ash (0.012 +/- 0.002%) and moisture (9.276 +/- 0.20%) were obtained in winter, autumn, and spring, respectively. Using G. latifolium from the Sinop Peninsula, good quality of agar with a gel strength ranging from 206.83 +/- 5.36 to 591.85 +/- 2.42 g cm(-2) was obtained, indicating its potential for commercial exploitation. The highest hysteresis temperature was obtained during summer with a maximum in June (48.63 +/- 0.18 degrees C) and a minimum in autumn (46.20 +/- 0.09 degrees C). Results of this study indicate that the best quality agar was obtained during the second period of the year and in autumn. FTIR analysis of agar extracted from G. latifolium showed a fairly constant spectrum that were recorded to contain high gel strengths and low sulfate residues. We conclude that the extracted agar is of good quality agar and may have the potential for commercial agar production.
  • [ X ]
    Öğe
    The effect of different extraction methods and pre-treatments on agar yield and physico-chemical properties of Gelidium latifolium (Gelidiaceae, Rhodophyta) from Sinop Peninsula Coast of Black Sea, Turkey
    (Springer, 2018) Ogretmen, Ozen Yusuf; Duyar, Hunkar Avni
    The present study aimed to investigate the effect of different pre-treatments and extractions methods on the yield and quality of agar extracted from Gelidium latifolium Bornet ex Hauck from the coast of Sinop Peninsula, Turkey, and to evaluate its potential as an economic source of agar for industrial applications. The different extraction methods including autoclave, water bath, and water bath plus magnetic stirrer were tested with various pre-treatments (no treatment, waiting for 15 h in pure water, washing with 80% ethanol). The agar yield and physico-chemical properties (gelling and melting temperature, pH, viscosity, and ash, and sulfate contents) were evaluated at the optimal extraction conditions. The highest agar yield (%) was recorded with the water bath plus magnetic stirrer extraction method (45.79 +/- 0.85% of dry wt), while the lowest yield was recorded with the autoclave extraction method (37.29 +/- 0.76%). The gelling and melting temperatures ranged between 39.06 +/- 0.26 and 37.16 +/- 0.16 degrees C, and 94.8 +/- 0.29 and 79.5 +/- 0.50 degrees C, respectively. The highest crude ash content was recorded with water bath plus magnetic stirrer extraction method (3.36 +/- 0.11%). The pH values ranged between 6.69 +/- 0.11 and 5.17 +/- 0.47. The agar viscosity ranged from 281.33 +/- 1.33 to 133.33 +/- 1.33 mPa s and total sulfate content was between 3.02 +/- 0.25 and 0.54 +/- 0.11%. The agar extracted from G. latifollium from Turkey seems to have potential industries applications considering its higher yield, desirable gelling and melting properties, optimum pH, ash, and sulfate content.