Browsing by Subject "Chlorophyll a"

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    Changes in β-carotene, chlorophyll and color of spinach puree during ohmic heating
    (2010) Yildiz H.; Icier F.; Baysal T.
    The spinach puree was heated from 30C to prescribed temperatures (60, 70, 80 or 90C) ohmically and conventionally. Ohmic heating was performed by application of four different voltage gradients in the range of 10-40 V/cm, while conventional heating was conducted at constant temperature in a water bath. Although ohmic heating time required from 30 to 70C was similar for water heating (129 ± 7 s) and ohmic heating by 20 V/cm (127 ± 2 s), faster heating (51 ± 0.5 s) could be obtained as the voltage gradient for ohmic heating increased to 30 V/cm. Ohmic heating caused browning more than conventional water heating for the same temperature range. The effect of voltage gradient applied was not found statistically significant on chlorophyll (total, a and b), β-carotene and color values (L, a, b, Lb/a, Lba, hue angle) (P < 0.05). On the other hand, temperature (60, 70, 80 or 90C) at constant voltage gradient (30 V/cm) affected color values of spinach puree (P < 0.05), whereas holding time (0 and 600 s) at constant temperature increased chlorophyll-a and β-carotene contents (P < 0.05). This increase could be caused by the possible enhancing effect of ohmic heating on β-carotene biosynthesis and formation of chlorophyll derivatives. It was concluded that ohmic heating could be applied to vegetable purees, resulting in high retention of color attributes and β-carotene. © 2009 Wiley Periodicals, Inc.
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    Effects of electroplasmolysis treatment on chlorophyll and carotenoid extraction yield from spinach and tomato
    (2011) Toprak Aktas E.; Yildiz H.
    In this study, the effects of electroplasmolysis on β-carotene, chlorophyll-a, chlorophyll-b and total chlorophyll contents of spinach extract and β-carotene and lycopene contents of tomatoes extracts were investigated. Three different voltage gradients (40, 60, 80 V/cm) and three different application periods (4, 8, 12 s) were used. The effects of water bath heating at different temperatures on the extraction yield of colorants were also studied. After pre-treatments, β-carotene, lycopene, chlorophyll-a, and chlorophyll-b extraction was performed. Total solid content, pH and titratable acidity of the spinach and tomato samples were also determined. In spinach, the highest extraction yield efficiency for β-carotene (19.7%) was obtained by water bath heating. The extraction yield efficiencies for chlorophyll-a, chlorophyll-b and total chlorophyll were 14.9%, 12.6% and 13.7% respectively, by the electroplasmolysis treatment at 60 V/cm for 8 s. In tomato, the highest increase in extraction yield efficiencies of β-carotene (139.1%) and lycopene (112.4%) was obtained by electroplasmolysis treatment at 80 V/cm for 4 s. © 2011 Elsevier Ltd. All rights reserved.