Browsing by Author "Gelderblom, W. C. A."

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    Changes in the phenolic composition and antioxidant activity of pinotage, cabernet sauvignon, chardonnay and chenin blanc wines during bottle ageing
    (South African Society for Enology and Viticulture, 2005) De Beer, D.; Joubert, E.; Gelderblom, W. C. A.; Manley, M.
    The effect of bottle ageing on the antioxidant activity of Pinotage, Cabernet Sauvignon, Chardonnay and Chenin blanc wines, using the 2,2'-azino-di-(3-ethylbenzothialozine-sulphonic acid) radical cation (ABTS•+) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH0) scavenging assays, was determined. Storage at 0°C, 15°C or 30°C for a period of 12 months resulted in a significant (p ≤ 0.05) decrease in both the total antioxidant activity (TAAAnTs and TAAoPPH) and the total phenol content of the wines. The antioxidant potency of the total phenols of most of the wines, which is a ratio of antioxidant activity to the total phenol content, also decreased. The total anthocyanins in the red wines decreased significantly (p ≤ 0.05) over 12 months except for storage at 0°C, while the flavanol content of the Pinotage, Cabernet Sauvignon and Chardonnay wines increased up to nine months storage with a subsequent decrease to 12 months. The flavonol content of all the wines decreased, while only minor changes in their hydroxycinnamate content were observed during the storage period. Understanding the complexity of these reactions may provide clues for stabilising especially red wines to preserve the antioxidant activity without losing the beneficial effects of colouring and flavour development during bottle ageing.
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    Mutations and other Risk indicators for Oesophageal Cancer among two distinct groups.
    (2005) Burger, H.; Barnard, D.; Van Helden, P. D.; Victor, T. C.; Abel, S.; Gelderblom, W. C. A.; Rossouw, G.; Wilken, E.; Marasas, W. F.O
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    Phenolic compounds : a review of their possible role as in vivo antioxidants of wine
    (South African Society for Enology and Viticulture, 2002) De Beer, D.; Joubert, E.; Gelderblom, W. C. A.; Manley, M.
    Phenolic compounds are a large and complex group of chemical constituents found in red and white wines which not only affect their quality, but also contribute to their beneficial health effects. The antioxidant properties of phenolic compounds are important in determining their role as protective agents against free radical-mediated disease processes. This review discusses the principles of oxidative stress and the resultant cellular damage caused by lipid peroxidation in vivo. Different groups of wine phenolic compounds are detailed, with specific reference to their in vitro antioxidant activity and their relative potency as free radical scavengers. The absorption and bioavailability of phenolic compounds from dietary sources is discussed.
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    South African herbal teas : Aspalathus linearis, Cyclopia spp. and Athrixia phylicoides - a review
    (Elsevier, 2008-10) Joubert, E.; Gelderblom, W. C. A.; Louw, Ann; De Beer, D.
    Rooibos (Aspalathus linearis (Brum.f) Dahlg.) and honeybush (Cyclopia Vent. species) are popular indigenous South African herbal teas enjoyed for their taste and aroma. Traditional medicinal uses of rooibos in South Africa include alleviation of infantile colic, allergies, asthma and dermatological problems, while a decoction of honeybushwas used as a restorative and as an expectorant in chronic catarrh and pulmonary tuberculosis. Traditional medicinal uses of Athrixia phylicoides DC., or bush tea, another indigenous South African plant with very limited localised use as herbal tea, include treatment of boils, acne, infected wounds and infected throats. Currently rooibos and honeybush are produced for the herbal tea market, while bush tea has potential for commercialisation. A summary of the historical and modern uses, botany, distribution, industry and chemical composition of these herbal teas is presented. A comprehensive discussion of in vitro, ex vivo and in vivo biological properties, required to expand their applications as nutraceutical and cosmeceutical products, is included, with the mainemphasis on rooibos. Future research needs include more comprehensive chemical characterisation of extracts, identification of marker compounds for extract standardisation and quality control, bioavailability and identification of bio-markers of dietary exposure, investigation of possible herb–drug interactions and plant improvement with regards to composition and bioactivity.