Monitoring the Effect of Micro-oxygenation before Malolactic Fermentation on South African Pinotage Red Wine with Different Colour and Phenolic Analyses

The use of micro-oxygenation and its effect on the quality of the red wine varietal, Pinotage, is largelyunknown. The influence of adding different oxygen dosages before malolactic fermentation on thephenolic composition and colour stabilisation of wine made from Pinotage was studied, and thesuitability of certain spectrophotometric and RP-HPLC analyses to determine these changes wereassessed in tanks of commercial lengths. Total oxygen dosages of 0 mg/L, 16 mg/L and 32 mg/L wereapplied, after which the wines underwent malolactic fermentation and maturation in the same tanks fortwo additional months. Decreases in anthocyanin concentration showed a strong inversely proportionalcorrelation with increasing polymeric pigment concentration. This suggests that the addition ofoxygen contributed to the early stabilisation of wine colour in Pinotage red wine. Overall, tanninconcentrations were not significantly influenced by the oxygen treatments, although lower levels wereobserved in wines treated with oxygen. An important finding of the study was that there appeared to belittle difference in the colour and phenolic composition of the wines between the 16 mg/L and 32 mg/Loxygen treatments. Good correlations were found between certain spectrophotometric techniques andthe RP-HPLC analysis used to study changes induced by micro-oxygenation (total anthocyanins, totalphenols). The colour and phenolic composition of Pinotage wine can be influenced before malolacticfermentation by micro-oxygenation. Some spectrophotometric phenolic analyses showed the sametendencies as observed with RP-HPLC (anthocyanins, monomeric flavan-3-ols, tannins), indicating theirsuitability to follow phenolic and colour changes induced by micro-oxygenation in Pinotage red wine

Linking climate change and progressive eutrophication to incidents of clustered animal mortalities in different geographical regions of South Africa

Cyanobacterial blooms have become an increasing problem in South African freshwater bodies. Since certain species of cyanobacteria are well-known for biosynthesis of potent hepatic and neurotoxins, such blooms can pose a significant threat to the health of animals and humans. The massiveproliferation of these organisms in rivers and lakes is largely due to progressive eutrophication. However, a warming trend in the Southern hemisphere, indicated by a threefold increase in the minimum temperature compared to maximum temperature between 1950 and 1990, is likely the cause of the increasing occurrence of toxic cyanobacterial bloom forming species, previously hampered by low water temperatures in different geographical regions of South Africa

Microcystis aeruginosa: source of toxic microcystins in drinking water

Cyanobacteria are one of the earth's most ancient life forms. Evidence of their existence on earth, derived from fossil records, encompasses a period of some 3.5 billion years in the late Precambrian era. Cyanobacteria are the dominant phytoplanton group in eutrophic freshwater bodies worldwide. They have caused animal poisoning in many parts of the world and may present risks to human health through drinking and recreational activity. Cyanobacteria produce two main groups of toxin namely neurotoxins and peptide hepatotoxins. They were first characterized from the unicellular species, Microcystis aeruginosa, which is the most common toxic cyanobacterium in eutrophic freshwater. The association of environmental parameters with cyanobacterial blooms and the toxicity of microcystin are discussed. Also, the synthesis of the microcystins, as well as the mode of action, control and analysis methods for quantitation of the toxin is reviewed. Key Words: Cyanobacteria, microcystins, mcyB gene, PCR-RFLP. African Journal of Biotechnology Vol.3(3) 2004: 159-16

Monetary value of the impacts of filamentous green algae on commercial agriculture: Results from two geographically different case studies

This paper presents estimates of the monetary value of the impact of eutrophication (algae) on commercial agriculture in two different catchments in South Africa. A production function approach is applied to estimate the monetary value of the impact of filamentous green algae on commercial agriculture in the Dwars River, Western Cape and the Loskop irrigation area, Groblersdal, in South Africa. The main emphasis was on the impacts of algal growth on farm profitability, which relied on detailed information on the impact, and the extent of the impact, of algae on farming practice. The paper presents the study areas, methodological approach, surveyed pollution impacts and the calculated monetary value of the impacts of such pollution. A short conclusion discusses some potential applications of the results. Initial results point towards a value of R1 887 per hectare per year for the Dwars River area and R2 890 per hectare per year for the Loskop irrigation area. The information can not only be used to compare different eutrophication mitigation strategies within the study areas and, to a lesser extent, similar areas outside these areas, but can also inform a process focusing on assessing the market potential for tradable pollution permits as a mitigation practice to manage water pollution in both catchments.Keywords: water quality, filamentous algae, economic impact, farmin

First report on the colony-forming freshwater ciliate Ophrydium versatile in an African river

Ophrydium versatile (Müller 1786) Ehrenberg 1830 – a symbiotic ciliate that forms gelatinous colonies – is widely distributed in temperate lakes in Europe and America, but has not previously been recorded from rivers. In this paper we report the first record of O. versatile in an African river, based on an identity confirmed by molecular taxonomic identification. The limnological conditions within the Lephalala River during the sampling period were characterised as oligotrophic with low DOC concentrations, similar to the conditions observed in temperate northern hemisphere lakes where these organisms have been recorded previously. The majority of O. versatile colonies occurred in areas where thin orange-coloured films containing high concentrations of iron (> 60% Fe) covered the substrate and bedrock of the river; this may be related to the abundant picophytoplankton that were associated with these films and oligotrophic conditions. The planktonic diatom Gomphonema venusta Passy was dominant in the water column throughout the study period and acted as an environmental indicator of low electrical conductivity (EC) conditions in the habitat where O. versatile colonies were recorded. Keywords: Lapalala River, oligotrophic indicator, water qualit

Effects of Abiotic Factors on Phenolic Compounds in the Grape Berry – A Review

Grape berry phenolic compounds are widely described in literature. Phenolics can be divided into two main groups: flavonoids and non-flavonoids, of which the flavonoids are the most important. The two bestknown groups of flavonoids are the anthocyanins and condensed tannins (also called proanthocyanidins).  Anthocyanins are responsible for the red colour in grapes. The condensed tannins (proanthocyanidins) are responsible for some major wine sensorial properties (astringency, browning, and turbidity) and areinvolved in the wine ageing processes. This review summarises flavonoid synthesis in the grape berry and the impact of environmental factors on the accumulation rate during ripening of each of the flavonoids.  The impact of the accumulated flavonoids in grapes and the resulting impact on the sensorial aspects of the wine are also discussed

Assessment of the genetic diversity of geographical unrelated Microcystis aeruginosa strains using amplified fragment length polymorphisms (AFLPs)

Molecular marker analysis is becoming increasingly capable of identifying informative genetic variation. Amplified fragment length polymorphism markers (AFLPs) are among the recent innovations in genetic marker technologies, and provide a greater capacity for genome coverage and more reproducible results than previous technologies. We have investigated the usefulness of AFLP, which is based on the selective amplification of genomic restriction fragments by PCR, to differentiate between geographical unrelated Microcystis strains. In total 23 strains were subjected to the AFLP fingerprinting. After analysis of the data on the basis of the average linkage method, known as the Unweighted Pair Group Method using Arithmetic averages (UPGMA), a dendrogram with four clusters was obtained. Cluster 1 consisted mainly of the NIES strains that originated from Japan, while in cluster 2 the European strains grouped together. The South African strains that originated from the northern part of the country group together in cluster 3, while the strains collected from the central and southern regions group together with the US strains in cluster 4. The study had reveals extensive evidence for the applicability of AFLP in cyanobacterial taxonomy, and furthermore clearly demonstrates the superior discriminative power of AFLP towards the differentiation of geographical unrelated Microcystis aeruginosa strains that belong to the same species, as well as highlighting the potential of this fingerprinting method in evolutionary studies.African Journal of Biotechnology Vol. 4 (5), pp. 389-399, 200

A ‘Mouth-feel Wheel’: terminology for communicating the mouth-feel characteristics of red wine

Abstract A hierarchically structured vocabulary of mouth-feel sensations elicited by red wines has been produced. Represented as a wheel, this structured vocabulary should assist tasters in their interpretation and use of terminology relating to 'in mouth' sensations produced by red wines. These terms and their definitions were generated by consulting the opinions of experienced wine tasters following exposure to an extensive range of commercial red wines. Logical relationships among the derived terms were formulated by analysis of 'sorting data' provided by a combined group of experienced winemakers and wine-tasters

Response of Grape and Wine Phenolic Composition in Vitis vinifera L. cv. Merlot to Variation in Grapevine Water Status

Grape and wine phenolic composition was monitored over two consecutive seasons in Vitis vinifera cv. Merlotfollowing application of irrigation treatments that produced seasonal average stem water potentials rangingbetween -0.7 MPa and -1.4 MPa. Fresh weight of berries was significantly reduced in response to water deficit,primarily due to decreases in pericarp weight. Increases in the concentration of grape anthocyanins andflavonols in response to water deficit were found when expressed per unit grape berry fresh weight. Skin-derivedtannin concentration in grape berries was not affected by the irrigation treatments. The concentration of grapederivedphenolics was monitored during five days of fermentation in a small-lot winemaking experiment. Duringfermentation, the concentration of anthocyanins and flavonols in wine were highest in the non-irrigated and lowfrequency-irrigated treatments, which was reflected in changes in the wine colour of ferments. Finished winesfrom non-irrigated and low frequency irrigated grapevines showed increases in bisulphite-resistant pigmentswhen compared with those irrigated at a high frequency, but differences in phenolic composition were minor.Increases in bisulphite-resistant pigments were associated with increases in vitisin A and polymeric pigmentin the first and second seasons of the study respectively. Ageing of wines for an 18-month period increasedbisulphite-resistant pigments, and treatment differences in wine colour density were enhanced, such thatincreases in both parameters were associated with the non-irrigated and low-frequency-irrigated treatments