Grape Heterogeneity Index: Assessment of Overall Grape Heterogeneity Using an Aggregation of Multiple Indicators

Uniform grape maturity can be sought by producers to minimise underripe and/or overripe proportions of fruit and limit any undesirable effects on wine quality. Considering that grape heterogeneity is a multifaceted phenomenon, a composite index summarising overall grape heterogeneity was developed to benefit vineyard management and harvest date decisions. A grape heterogeneity index (GHI) was constructed by aggregating the sum of absolute residuals multiplied by the range of values from measurements of total soluble solids, pH, fresh weight, total tannins, absorbance at 520 nm (red colour), 3-isobutyl-2-methoxypyrazine, and malic acid. Management of grape heterogeneity was also studied, using Cabernet Sauvignon grapes grown under four viticultural regimes (normal/low crop load, full/deficit irrigation) during the 2019/2020 and 2020/2021 seasons. Comparisons of GHI scores showed grape variability decreased throughout ripening in both vintages, then significantly increased at the harvest time point in 2020, but plateaued on sample dates nearing the harvest date in 2021. Irrigation and crop load had no effect on grape heterogeneity by the time of harvest in both vintages. Larger vine yield, leaf area index, and pruning weight significantly increased GHI score early in ripening, but no significant relationship was found at the time of harvest. Differences in the Ravaz index, normalised difference vegetation index, and soil electrical conductivity did not significantly change the GHI score.Claire E. J. Armstrong, Pietro Previtali, Paul K. Boss, Vinay Pagay, Robert G. V. Bramley, and David W. Jeffer

Distribution of 3-Isobutyl-2-methoxypyrazine across Rachis Components of Vitis vinifera Shiraz and Cabernet Sauvignon

Published 18 April 2023. Special Issue - 18th Australian Wine Industry Technical Conference.Rootstock can significantly alter the concentration of methoxypyrazines (MPs) in the bunch stem (rachis) of Vitis vinifera L. cv. Cabernet Sauvignon and Shiraz, which has implications for winemaking and wine style. The distribution of MPs across the rachis is an important consideration, but such information was not available. This study aimed to address this research question by comparing MP concentrations in different rachis components throughout grape maturation and in the absence of ambient light. Shiraz and Cabernet Sauvignon bunches were sampled throughout development, segmented into four components (peduncle, top rachis, bottom rachis, and pedicel), and 3-isobutyl-2-methoxypyrazine (IBMP) was quantified in each. For both cultivars, IBMP showed a negative correlation with grape maturity, with concentrations in pedicel at harvest being significantly higher than other rachis components. Additionally, light exclusion significantly increased IBMP concentrations in all rachis segments. The concentration of IBMP varied significantly between different rachis components. The greatest concentrations were measured in the pedicel, which also contributed the largest proportion among the components to total rachis by weight. Due to elevated IBMP concentrations in rachis and the difficulties in excluding matter other than grape from a fermentor, the presence of pedicel during fermentation could produce Shiraz and Cabernet Sauvignon wines with higher concentrations of MPs, thereby potentially increasing vegetal sensory characteristics.Ross D. Sanders, Paul K. Boss, Dimitra L. Capone, Catherine M. Kidman, Emily L. Nicholson, and David W. Jeffer

Birthing practices of traditional birth attendants in South Asia in the context of training programmes

Traditional Birth Attendants (TBA) training has been an important component of public health policy interventions to improve maternal and child health in developing countries since the 1970s. More recently, since the 1990s, the TBA training strategy has been increasingly seen as irrelevant, ineffective or, on the whole, a failure due to evidence that the maternal mortality rate (MMR) in developing countries had not reduced. Although, worldwide data show that, by choice or out of necessity, 47 percent of births in the developing world are assisted by TBAs and/or family members, funding for TBA training has been reduced and moved to providing skilled birth attendants for all births. Any shift in policy needs to be supported by appropriate evidence on TBA roles in providing maternal and infant health care service and effectiveness of the training programmes. This article reviews literature on the characteristics and role of TBAs in South Asia with an emphasis on India. The aim was to assess the contribution of TBAs in providing maternal and infant health care service at different stages of pregnancy and after-delivery and birthing practices adopted in home births. The review of role revealed that apart from TBAs, there are various other people in the community also involved in making decisions about the welfare and health of the birthing mother and new born baby. However, TBAs have changing, localised but nonetheless significant roles in delivery, postnatal and infant care in India. Certain traditional birthing practices such as bathing babies immediately after birth, not weighing babies after birth and not feeding with colostrum are adopted in home births as well as health institutions in India. There is therefore a thin precarious balance between the application of biomedical and traditional knowledge. Customary rituals and perceptions essentially affect practices in home and institutional births and hence training of TBAs need to be implemented in conjunction with community awareness programmes

Examining conceptions of writing in TESOL and English Education journals: Toward a more integrated framework for research addressing multilingual classrooms

We present a review of literature drawn from two prominent journals in the fields of Teaching English to Speakers of Other Languages (TESOL Quarterly) and English Education (Research in the Teaching of English) that publish writing research regarding secondary and lower-division postsecondary learners. The purpose of the review is to compare how the two journals represent conceptions of writing — conceptions that shape research designs, data analyses, and the interpretations of findings. Results suggest that, while the two journals share common theoretical concerns with the uses of language, they differ with respect to how they represent the goals and functions of extended written composition in educational settings. We conclude by discussing the implications of our findings for future research thatmore deliberately integrates knowledge across the respective fields of English Education and TESOL. Such an integrated approach, we argue, can ultimately help teachersmake more informed decisions about how best to differentiate writing instruction in linguistically heterogeneous classrooms.Language Use in Past and Presen

Linking the sensory properties of chardonnay grape Vitis vinifera cv. berries to wine characteristics

Formal or informal sensory analyses of grapes are often used to determine when a parcel of fruit should be harvested to produce a certain wine style. This study investigated whether relationships exist between sensory perceptions and basic chemical measures of Chardonnay grape berries and the corresponding wines. Chardonnay grape parcels were harvested at commercial maturity from across South Australia in vintages 2015 and 2016, yielding a total of 25 and 24 samples, respectively. Grapes were evaluated using berry sensory assessment (BSA) and vinified identically using small-scale winemaking, and the resulting wines were evaluated with descriptive sensory analysis. Sensory assessors were trained in the respective sensory evaluation methods. Chardonnay grape and wine samples were discriminated by the panel according to sensory attributes, and the fruit could also be discriminated by basic chemistry measures. However, differences in Chardonnay wines were subtle compared with those in grapes, as indicated by low effect sizes. Moderate validation models (R²Val = 0.53 to 0.81) of partial least squares regression (PLSR) 1 were determined in the 2015 vintage, using BSA attributes as x-variables and wine sensory attributes as y-variables, but poor models were obtained with the 2016 vintage (R²Val < 0.5). In the 2015 models, relationships were found for wine attributes of heat, sourness, and astringency, possibly due to slight variations in ripeness. Strong relationships that revealed wine style from variations in grapes were not found. Overall, relating the sensory characteristics of Chardonnay grapes to the wines was challenging and indicated that variation in style of these varietal wines does not greatly depend on the raw grape material.Jun Niimi, Paul K. Boss, David W. Jeffery and Susan E.P. Bastia

Effect of grape heterogeneity on wine chemical composition and sensory attributes for Vitis vinifera cv. Cabernet Sauvignon

Background and Aims: The wine industry widely acknowledges that grape heterogeneity exists throughout any given vineyard at the time of harvest. There is a lack of understanding, however, of the effects that heterogeneity has on wine composition and sensory qualities. This study compared the chemical composition and sensory attributes of wines produced using parcels of grapes with known heterogeneity. Methods and Results: Cabernet Sauvignon berries were sorted into maturity classes using five density baths. Winemaking was undertaken with a varying proportion of sorted berries to obtain wines arising from low, moderate and high grape heterogeneity musts, containing the same level of TSS for comparison to a Control wine that represented the inherent heterogeneity of the harvested vines. Wines were distinguished by the concentration of 3-isobutyl-2-methoxypyrazine, total anthocyanins and total phenolics, with the low heterogeneity wine having the highest values of each measurement. The high heterogeneity wine was characterised by a higher concentration of acetic acid. Principal component analysis of rate-all-that-apply sensory attribute scores revealed that low and moderate heterogeneity wines were characterised by floral and pepper aroma attributes, and the high heterogeneity wine by sour taste. Conclusions: The differing levels of grape heterogeneity had a subtle effect on Cabernet Sauvignon wine colour, aroma and taste attributes, but it was demonstrated that the level of grape heterogeneity could be of relevance if it translated into differences in wine quality and style. Significance of the Study: The potential impact of grape heterogeneity on the chemical composition and sensory profile of Cabernet Sauvignon wine was highlighted.C.E.J. Armstrong, R. Ristic, P.K. Boss, V. Pagay, D.W. Jeffer

Use of Machine Learning with Fused Spectral Data for Prediction of Product Sensory Characteristics: The Case of Grape to Wine

Generations of sensors have been developed for predicting food sensory profiles to circumvent the use of a human sensory panel, but a technology that can rapidly predict a suite of sensory attributes from one spectral measurement remains unavailable. Using spectra from grape extracts, this novel study aimed to address this challenge by exploring the use of a machine learning algorithm, extreme gradient boosting (XGBoost), to predict twenty-two wine sensory attribute scores from five sensory stimuli: aroma, colour, taste, flavour, and mouthfeel. Two datasets were obtained from absorbance-transmission and fluorescence excitation-emission matrix (A-TEEM) spectroscopy with different fusion methods: variable-level data fusion of absorbance and fluorescence spectral fingerprints, and feature-level data fusion of A-TEEM and CIELAB datasets. The results for externally validated models showed slightly better performance using only A-TEEM data, predicting five out of twenty-two wine sensory attributes with R2 values above 0.7 and fifteen with R2 values above 0.5. Considering the complex biotransformation involved in processing grapes to wine, the ability to predict sensory properties based on underlying chemical composition in this way suggests that the approach could be more broadly applicable to the agri-food sector and other transformed foodstuffs to predict a product’s sensory characteristics from raw material spectral attributes.Claire E. J. Armstrong, Jun Niimi, Paul K. Boss, Vinay Pagay, and David W. Jeffer

Machine learning for classifying and predicting grape maturity indices using absorbance and fluorescence spectra

Available online 20 September 2022Absorbance-transmission and fluorescence excitation-emission matrix (A-TEEM) spectroscopy was investigated as a rapid method for predicting maturity indices using Cabernet Sauvignon grapes produced under four viticulture treatments during two growing seasons. Machine learning models were developed with fused spectral data to predict 3-isobutyl-2-methoxypyrazine (IBMP), pH, total tannins (Tannin), total soluble solids (TSS), and malic and tartaric acids based on the results from traditional analysis methods. Extreme gradient boosting (XGB) regression yielded R² values of 0.92-0.96 for IBMP, malic acid, pH, and TSS for externally validated (Test) models, with partial least squares regression being superior for TSS prediction (R² = 0.97). R² values of 0.64-0.81 were achieved with either approach for tartaric acid and Tannin predictions. Classification of grape maturity, defined by quantile ranges for red colour, IBMP, malic acid, and TSS, was investigated using XGB discriminant analysis, providing an average of 78 % correctly classified samples for the Test model.Claire E.J. Armstrong, Adam M. Gilmore, Paul K. Boss, Vinay Pagay, David W. Jeffer