Investigation of Thiol Levels in Young Commercial South African Sauvignon Blanc and Chenin Blanc Wines Using Propiolate Derivatization and GC-MS/MS

In this work, the ethyl propiolate method for analysing thiols in white wine by GC-MS, originally proposed by Herbst-Johnstone et al.) (2013), has been adapted to GC-MS/MS and has been validated. The method performance has shown improvement in terms of sensitivity (limit of detection, LOD) and of the number of compounds measured. In addition to 3-mercaptohexanol (3MH), 3-mercaptohexyl acetate (3MHA), and 4-mercapto-4-methylpentan-2-one (4MMP), the adapted method can also measure 2-furanmethanethiol (FMT) and makes use of a commercially-available internal standard (IS), 4-methoxy-2-methyl-2-butanethiol (4M2M2B, IS). The proposed method was applied to determine thiol levels in young commercial South African Sauvignon and Chenin Blanc wines. The samples (n=20 for each cultivar) were chosen according to a high frequency of the typical descriptors associated with this class of impact compounds. 3MH was found at 178-904 ng/L and 99-1124 ng/L, and 3MHA at 23-151 ng/L and 5-253 ng/L in Sauvignon and Chenin Blanc respectively. 4MMP was present in Sauvignon Blanc in concentrations up to 21.9 ng/L, but in none of the Chenin Blanc samples

Correlating Sensory Assessment of Smoke-Tainted Wines with Inter-Laboratory Study Consensus Values for Volatile Phenols

Vineyard exposure to wildfire smoke can taint grapes and wine. To understand the impact of this taint, it is imperative that the analytical methods used are accurate and precise. This study compared the variance across nine commercial and research laboratories following quantitative analysis of the same set of smoke-tainted wines. In parallel, correlations between the interlaboratory consensus values for smoke-taint markers and sensory analyses of the same smoke-tainted wines were evaluated. For free guaiacol, the mean accuracy was 94 ± 11% in model wine, while the free cresols and 4-methylguaiacol showed a negative bias and/or decreased precision relative to guaiacol. Similar trends were observed in smoke-tainted wines, with the cresols and glycosidically bound markers demonstrating high variance. Collectively, the interlaboratory results show that data from a single laboratory can be used quantitatively to understand smoke-taint. Results from different laboratories, however, should not be directly compared due to the high variance between study participants. Correlations between consensus compositional data and sensory evaluations suggest the risk of perceivable smoke-taint can be predicted from free cresol concentrations, overcoming limitations associated with the occurrence of some volatile phenols, guaiacol in particular, as natural constituents of some grape cultivars and of the oak used for barrel maturation.James W. Favell, Kerry L. Wilkinson, Ieva Zigg, Sarah M. Lyons, Renata Ristic, Carolyn J. Puglisi, Eric Wilkes, Randell Taylor, Duane Kelly, Greg Howell, Marianne McKay, Lucky Mokwena, Tim Plozza, Pei Zhang, AnhDuyen Bui, Ian Porter, Orrin Frederick, Jasha Karasek, Colleen Szeto, Bruce S. Pan, Steve Tallman, Beth Anne McClure, Hui Feng, Eric Hervé, Anita Oberholster, Wesley F. Zandberg, and Matthew Noesthede

The role of locus of control in nyaope addiction treatment

Background: Nyaope addiction is a significant health and social problem affecting some South African communities. With reported nyaope rehabilitation success rates of less than 3% and estimated dropout rates of 40%, improvement in the rehabilitation rates is essential. As locus of control (LOC) is a recognised predictive factor in the onset of substance use and rehabilitation outcomes, a rehabilitation programme aligned to the LOC orientation of the user could result in improved recovery outcomes. This study aimed to determine the LOC of nyaope users.Methods: Consenting adult male and female nyaope users voluntary participated in this quantitative study. After convenient sampling, 115 nyaope users admitted to drug rehabilitation centres registered and funded by the Gauteng Department of Social Development and 106 nyaope users from the streets of urban areas of Tshwane completed a self-administered validated questionnaire. LOC orientation was determined by giving participants 13 statements from which they had to choose the option that best described their situation in relation to drug addiction.Results: A total of 24.5% (47/192) of the respondents could be classified as having an external LOC orientation while 75.5% (145/192) were classified as having an internal LOC orientation.Conclusions: By determining the LOC orientation of a nyaope user, rehabilitation programmes could be aligned to suit the personality of the user leading to a better chance of successful recovery with fewer cases of readmission

Investigation of thiol levels in young commercial South African Sauvignon Blanc and Chenin Blanc wines using propiolate derivatization and GC-MS/MS

CITATION: Coetzee, C. et al. 2018. Investigation of thiol levels in young commercial South African Sauvignon Blanc and Chenin Blanc wines using propiolate derivatization and GC-MS/MS. South African Journal of Enology and Viticulture, 39(2):180-184, doi:10.21548/39-2-2683.The original publication is available at https://www.journals.ac.za/index.php/sajevIn this work, the ethyl propiolate method for analysing thiols in white wine by GC-MS, originally proposed by Herbst-Johnstone et al.) (2013), has been adapted to GC-MS/MS and has been validated. The method performance has shown improvement in terms of sensitivity (limit of detection, LOD) and of the number of compounds measured. In addition to 3-mercaptohexanol (3MH), 3-mercaptohexyl acetate (3MHA), and 4-mercapto-4-methylpentan-2-one (4MMP), the adapted method can also measure 2-furanmethanethiol (FMT) and makes use of a commercially-available internal standard (IS), 4-methoxy-2-methyl-2-butanethiol (4M2M2B, IS). The proposed method was applied to determine thiol levels in young commercial South African Sauvignon and Chenin Blanc wines. The samples (n=20 for each cultivar) were chosen according to a high frequency of the typical descriptors associated with this class of impact compounds. 3MH was found at 178-904 ng/L and 99-1124 ng/L, and 3MHA at 23-151 ng/L and 5-253 ng/L in Sauvignon and Chenin Blanc respectively. 4MMP was present in Sauvignon Blanc in concentrations up to 21.9 ng/L, but in none of the Chenin Blanc samples.https://www.journals.ac.za/index.php/sajev/article/view/2683Publisher's versio

Strategies to improve historically disadvantaged university staff’s wellbeing and administration of academic programmes during COVID-19: A descriptive survey study

The coronavirus (COVID-19) pandemic has brought the world to a standstill, impacting negatively on human mortality and morbidity. Currently, most countries are on a national lockdown as a way of curbing the rapid spread of the virus. Although desirable, nationwide lockdown continues to hamper the smooth running of the government’s key strategic sectors including the schooling system. In this descriptive qualitative study, we explored university staff (n = 87; Meanage = 38.54; males = 50.6%, females = 49.4%) views on strategies that could improve their wellbeing and administration of academic programmes during-and-immediately after the COVID-19 national lockdown. Participants were sampled conveniently and responded to an open-ended questionnaire online. The participating staff recommended five key strategies that were thematically analysed, which are as follows: a) improved communication; b) provision of efficient ICT infrastructure; c) consideration of compensatory academic measures; d) on-campus COVID-19 risk management strategy; and e) provision of online and on-campus psychological services. Based on these findings, it is recommended that the historically disadvantaged universities should consider implementing strategies for enhancing the staff’s wellbeing and administration of academic activities. However, whether the suggested strategies could yield positive results, post-implementation evaluation research may be needed. For future preparedness, present findings imply that institutions of higher learning need to put in place contingency plans for efficient communication in times of crises similar to COVID-19 while investing in efficient ICT infrastructure for remote learning, teaching, and research

Propelling low-carbon mobility through experiential learning : findings in Tshwane, Johannesburg, and Cape Town

Three “low-carbon challenges” were held, in Tshwane and Johannesburg in 2015, and Cape Town during 2016. In each city, teams of racers traversed a route using non-motorised, public, paratransit or electric transport, in order to finish with the lowest carbon footprint. An objective of the challenges was to highlight the triggers and changes required for climate change mitigation in passenger transport. The implicit approach was experiential learning by participating public officials, business executives, students, and transport operators, both in organising and during the challenges (80 racers, 25 city officials, and 10 transport businesses). The “business unusual” and multi-faceted nature of the challenges sought to surface factors and dynamics that could add to cities’ own research and strategies for low-carbon mobility, or might trigger personal travel behaviour change. Organising the challenges revealed how existing arrangements facilitate (or not) low-carbon mobility; and doing the challenge offered participants better understanding of the city’s plans and challenges, exposure to others’ daily travel experiences, and experience of various available transport options. This paper presents qualitative responses on the impacts of these one-off events up to two years later on participants’ thinking, workplace practices or personal travel behaviour.Papers presented at the 36th Southern African Transport Conference, CSIR International Convention Centre, Pretoria, South Africa on 10-13 July 2017.Transportation research board of the national academie

Potentially smoke tainted red wines: volatile phenols and aroma attributes

CITATION: McKay, M., et al. 2019. Potentially smoke tainted red wines : volatile phenols and aroma attributes. South African Journal of Enology and Viticulture, 40(2), doi:10.21548/40-2-3270.The original publication is available at http://www.journals.ac.za/index.php/sajevMalodourous compounds, including volatile phenols (VPs) are frequently found at concentrations below their odour thresholds in wine, and may therefore be considered to present no threat to wine quality. Most investigations into smoke taint quantify compounds by chemical/analytical means, or investigate sensory effects of supra- and peri-threshold contamination in model wine. In this project, twelve wines submitted by the South African industry as ‘faulty’ and/or smoke tainted were screened for VPs using GC-MS, and characterized using Descriptive Analysis (DA) by a sensory panel highly trained in smoke taint evaluation. Results were compared statistically to elucidate relationships between chemical and sensory characteristics. It was demonstrated, using the combined dataset, that concentration and composition of VPs in the wines correlated well with certain sensory attributes. Guaiacol was present in most samples at peri- or supra-threshold levels, but did not cause taint unless in combination with other phenols, when it was associated with ‘smoky’, ‘ashy’ and ‘herbaceous’ attributes. Wines with very low levels of VPs showed more sweet-associated aroma characteristics. Wines with supra-threshold levels of VPs showed negative attributes (‘chemical/plastic’, ‘tar/BR’ and ‘medicinal/Elastoplast™’). In some cases, sensory effects (‘earthy/dusty/potato skin’, ‘mouldy/musty’ and ‘cooked veg’) could not be attributed to peri- or supra-threshold concentrations, but seemed to be due to combinations of volatile phenols at subthreshold levels. Associations between negative attributes and historical bushfire events prior to harvest were found for a number of the wines. This study emphasizes the importance of understanding effects of VPs on wine aroma, and escalating awareness and sensitivity to these issues in the wine industry.https://www.journals.ac.za/index.php/sajev/article/view/3270Publisher's versio

Effect of modified atmosphere packaging and storage temperature on volatile composition and postharvest life of minimally-processed pomegranate arils (cvs. ?Acco? and ?Herskawitz?)

Please help populate SUNScholar with the full text of SU research output. Also - should you need this item urgently, please send us the details and we will try to get hold of the full text as quick possible. E-mail to [email protected]. Thank you.Journal Articles (subsidised)AgriwetenskappeHortologi

Determination of volatile phenol in cabernet sauvignon wines, made from smoke-affected grapes, by using HS-SPME GC-MS

CITATION: De Vries, C. J., et al. 2016. Determination of volatile phenol in cabernet sauvignon wines, made from smoke-affected grapes, by using HS-SPME GC-MS. South African Journal for Enology and Viticulture, 37(1): 15-21, doi:10.21548/37-1-754.The original publication is available at http://www.journals.ac.zaThe increased incidence of vegetation fires near vineyards in the Western Cape, South Africa has led to growing concern over the appearance of smoke taint in the affected grapes. This study focused on the effect of smoke exposure on the volatile phenol (VP) composition of wines made from affected grapes over two vintages (2012 and 2013). Cabernet Sauvignon grapes were exposed, 10 days post-véraison, to a single, hour-long treatment with smoke derived from burning a mixture of vegetation (including fynbos) under controlled conditions in enclosures. Enclosures were sealed for 24 h after exposure, and then removed. Grapes were allowed to ripen and wines were then produced. Wines were analysed by headspace gas chromatography mass spectrometry (HS-SPME GC-MS) for selected volatiles. The results of the investigation show that the exposure of grapes to smoke during ripening leads to the accumulation of VPs that were detected in wines. The detected VPs were guaiacol, phenol and the cresols. Smoke exposure of grapes during ripening may have a negative impact on wine quality due to the accumulation of these compounds.http://www.journals.ac.za/index.php/sajev/article/view/754Publisher's versio