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  • Blackwell Publishing Ltd  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 70 (2005), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : Water, an inexpensive and environmentally friendly solvent is an ideal solvent for industrial extraction of phenolics, but its use is limited due to poor extraction efficiency at low temperatures. In this study, subcritical water (SW) and subcritical sulfured water (SSW) (containing 1400 μg/mL sodium metabisulfite) extractions of grape skin phenolics were conducted over the temperature range of 100 to 160°C in 10°C increments for a short time (40 s), and compared with conventional hot water or aqueous 60% (v/v) methanol extractions (50°C, 1 h). The composition and contents of anthocyanins, flavonols, hydroxycinnamates, phenolic acids, and antioxidant capacities (Oxygen Radical Absorbing Capacity [ORAC]) in the extracts were determined. Increasing SW extraction temperature from 100 to 160°C resulted in a linear increase in ORAC values, but extraction temperatures 〉 110°C resulted in decreased contents of individual and total anthocyanins. Subcritical sulfured water extracts had higher levels of total anthocyanins and total phenolics than SW extracts. The SW and SSW extracts had comparable or higher levels of anthocyanins and ORAC values than extracts obtained using conventional hot water or 60% methanol. Subcritical water at 100 to 110°C appears to be an excellent alternative to organic solvents to extract anthocyanins and other phenolics from dried red grape skin and possibly other grape processing byproducts.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : The effects of hot and cold (nonheated) pressing on yield, quality components, and nutraceutical content of juice, grapes, and press fractions (seeds and skins) from Black Beauty (Vitis rotundifolia) and Sunbelt (Vitis labruscana L.) grape cultivars were evaluated. Heating the must before pressing increased juice yield, titratable acidity, red color, brown/yellow pigments, and darkness and decreased the press fraction yield and juice pH in both cultivars. Sunbelt juice from the heated must had the highest yield (786 L/metric ton), red color, brown/yellow pigments, and darkness. Black Beauty nonheated must had the largest press fraction (43%) but the lowest red color, brown/yellow pigments, and darkness in the juice. The juice generally had less total phenolics, total anthocyanins, and oxygen radical absorbance capacity (ORAC) than the whole grapes. The juice from heated Black Beauty and Sunbelt musts had the highest total phenolics (1354 and 1937 mg/L, respectively) and anthocyanins (414 and 513 mg/L, respectively). Although the data for seeds and skins are on a dry basis, the press fractions had higher levels of phenolics and ORAC than the whole grapes and juice. The dried seeds had more phenolics and less anthocyanins than the skins. The highest total phenolic level (95338 mg/kg) equivalents and ORAC level (1100 μmol trolox/g) was in Black Beauty seeds from nonheated must. The skins of nonheated Sunbelt had the highest anthocyanins (11889 mg/kg). Because the press fractions of both cultivars had high ORAC values and total phenolic levels, products with nutraceutical benefits could be developed.
    Type of Medium: Electronic Resource
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