Yazar "Cemeroglu, Bekir" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    Effects of temperature, solid content and pH on the stability of black carrot anthocyanins
    (Elsevier Sci Ltd, 2007) Kirca, Aysegul; Ozkan, Mehmet; Cemeroglu, Bekir
    Anthocyanin stability of black carrots was studied at various solid contents (11, 30, 45 and 64 degrees Brix) and pHs (4.3 and 6.0) during both heating, at 70-90 degrees C, and storage at 4-37 degrees C. Monomeric anthocyanin degradation fitted a first-order reaction model. Degradation of monomeric anthocyanins increased with increasing solid content during heating, while it decreased during storage. For example, at pH 4.3, half-life periods for anthocyanins at 30, 45 and 64 degrees Brix were, respectively, 8.4, 6.9 and 5.2 h during heating at 80 degrees C and 18.7, 30.8 and 35.9 weeks during storage at 20 degrees C. At 30-64 degrees Brix, increasing pH from 4.3 to 6.0 enhanced the degradation of anthocyanins during heating. The effect of pH on thermal stability of anthocyanins was also studied at six different pHs (2.5-7.0) in citrate-phosphate buffer solutions and significant decrease in anthocyanin stability was observed at pHs above 5.0. Higher activation energies (E-a) were obtained during heating than during storage with increasing solid contents. At 30-64 degrees Brix, E-a values ranged from 68.8 to 95.10 mol(-1) during heating and from 62.1 to 86.2 kJ mol(-1) during storage. Q(10) values at 20-37 degrees C were as high as 3.1 at 45 degrees Brix and 3.6 at 64 degrees Brix. (c) 2006 Elsevier Ltd. All rights reserved.
  • [ X ]
    Öğe
    Storage stability of strawberry jam color enhanced with black carrot juice concentrate
    (Wiley, 2007) Kirca, Aysegul; Ozkan, Mehmet; Cemeroglu, Bekir
    Black carrot juice concentrate was added to enhance the color of strawberry jams prepared from two locally grown cultivars, Osmanli and Kara. Compared to other cultivars processed to jams, these two cultivars are lightly colored but very aromatic. Color and pigment stability of colored and noncolored (control) strawberry jams were studied during storage. The use of black carrot concentrate as a source of natural colorant stabilized the color of strawberry jam. The stabilization was more noticeable for jams prepared from Osmanli cultivar. Monomeric anthocyanin degradation was fitted to a first-order reaction model. Storage temperature had a strong influence on anthocyanin degradation. As the storage temperature increased, the stability of anthocyanins decreased significantly in both colored and noncolored jams. Parallel to decrease in monomeric anthocyanins, hue (h degrees) values of all jam samples increased throughout the storage. However, increase in h degrees values was much smaller in colored samples than in noncolored samples. High correlation was found between h degrees value and anthocyanin concentration at 22C (r = 0.910-0.978) and 37C (r = 0.931-0.981).