A Review of Tannin Determination Methods Using Spectrophotometric Detection in Red Wines and Their Ability to Predict Astringency

Astringency is an important sensory attribute that influences red wine quality. The astringent sensation inside the mouth is caused by a group of molecules called tannins. These molecules can be quantified and analysed by several numbers of methods, such as the Bate Smith method, Adams Harbertson assay, and methylcellulose precipitation method. All these methods are colourimetric, however they differ on the principle on which they are based and, as well as on the tannin pool they are able to measure. In the literature, it is possible to find a wide range of concentrations of tannins for the main red wines varieties, which have been evaluated by the methods herein reviewed. For instance, higher tannin concentrations are obtained using the Bate Smith method (2.08-3.48 g/L tannin) compared with the Adams Harbertson assay (0.58-0.14 g/L tannin), which exhibit the lowest results. However, studies that directly compare results obtained with these methods are scarce. The aim of this work is to compare tannin concentrations in red wines and along with how sensory astringency correlates with tannin concentration measured by these three methods

S-Abscisic acid, 2-chloroethylphosphonic acid and indole-3-acetic acid treatments modify grape (Vitis vinifera L. 'Cabernet Sauvignon') hormonal balance and wine quality

The phenolic composition of red wine strongly determines its quality. Even when the applications of plant  growth regulator (PGR) affect grape quality, there is  almost no information on the effect of these treatments  on the grape’s internal hormonal balance and the wine  composition and quality. In the present study, changes in the internal hormonal content following the application of (+)-S-abscisic acid (S-ABA), 2-chloroethylphosphonic acid (CEPA) and indole-3-acetic acid (IAA) at veraison were examined to determine their effects on 'Cabernet Sauvignon' grapes and wine composition in a plants in containers experiment and in a commercial vineyard experiment. Applied PGRs had a significant effect on the hormonal balance and phenolic composition of grape skins. The S-ABA-treated grapes showed a significantly higher skin internal free abscisic acid concentration in the plants in container experiment and the CEPA-treated grapes showed a reduction in skin internal IAA concentration in the commercial vineyard experiment. Winemaking was performed in the commercial vineyard experiment. Wine’s chemical composition was affected by these treatments and an up-to 63 % increase in malvidin-3-glucoside concentration and an up-to 70 % increase in total tannin concentration were found in wines made from the CEPA-treated grapes. The alcohol content was 10.3 % higher (from 12.6 to 13.9 % v v-1) in wines made from the CEPA-treated grapes. No significant differences in the wine sensory attributes (aroma and mouth-feel) between the control and the PGR-treated wines were identified by a sensory panel.

Astringency sub-qualities of red wines and the influence of wine–saliva aggregates

Astringency is a sensory attribute, related to the quality and mouthfeel of red wines. However, the origin of astringency sub-qualities, such as the typical drying astringency found in immature grapes, is still unknown. Astringency of red wines with similar tannin content but different astringency sub-qualities, from different harvest dates, is studied. Astringency was characterised in terms of friction coefficient, polyphenol content, sensory analysis and tannin/salivary–proteins aggregates characterisation. A different evolution during ripening was found for both Cabernet Sauvignon and Carménère, and tannin–protein aggregates showed differences in size, shape and surface. The velvety sub-quality appears to be related to aggregates with low precipitation, and with specific surface characteristics as roundness and Feret diameter. Results from this work propose an effect of aggregates on sensory perception and opens the possibility to explore their effect on oral lubrication

Chile's export diversification since 1960: A free market miracle or mirage?

Conventional wisdom has proclaimed Chile's recent economic development a 'free market miracle'. In an examination of Chile's export diversification experience, this article departs from that view. By analysing the dynamics underlying the emergence of the salmon, fruit, forestry and wine sectors in Chile's export basket since the 1960s, the study sheds light on the crucial role of industrial policy in the process of capability accumulation that shapes new industries. The article undertakes a qualitative historical analysis of the scope and nature of policy interventions in each of the four sectors and conducts a quantitative policy evaluation using the difference-in-difference method. It finds that public institutions are essential in overcoming market failures inhibiting the emergence of new industries. Specifically, it shows that the government has a key role to play as a catalyst of human capital accumulation, as a venture capitalist, in trade promotion, and in ensuring 'national' sector reputation through a strong regulatory and quality control role. By elaborating on the dynamic process of structural transformation and capability accumulation, this article contributes to theoretical debates on the role of vertical policies in the emergence of new competitive sectors, and debates relating to static versus dynamic approaches to comparative advantage

Investigating trophic ecology and dietary niche overlap among morphs of Lake Trout in Lake Superior

Four morphs of Lake Trout (Salvelinus namaycush, Walbaum 1792) have been identified in Lake Superior: leans, siscowets, humpers, and redfins. In this comprehensive study, the trophic ecology of Lake Trout morphs were characterized using stomach content, fatty acid, and stable isotope data. Stomach content results indicated a predominately piscivorous diet for leans, siscowets, and redfins, whereas humper diets were comprised of 50% fish and 50% Mysis by mass. Humper and siscowets were most similar in their dietary fatty acid profiles, whereas redfins had the most distinct dietary fatty acid profile. Results from stable isotope analysis revealed some among-morph differences along a pelagic-profundal consumption gradient (34S), but there were no significant differences in trophic position (15N) or basal carbon sources among morphs (13C). Using the recently developed nicheROVER software package, 4-dimensional trophic niches for each morph were quantified using stable isotope ratios (δ13C, δ15N, and δ34S) and fatty acid profiles (30 dietary fatty acids, condensed to one axis). Humpers had the largest 4-dimensional niche regions of all four morphs, and redfins had the smallest. Pairwise probability of overlap among morphs in these four-dimensional niche regions was determined to be < 50% in most cases. Overall, stomach content results indicate that humpers diets were more planktivorous than the other morphs, consistent with previous research. Results of the niche overlap analysis suggests some degree of generalist feeding for all morphs. Better characterization of seasonal variation in diet using tracers that reflect more recent feeding (e.g., fatty acids, stomach contents, and/or stable isotope analyses performed on tissues that turnover more quickly than muscle) are needed to further elucidate among-morph differences and similarities in diet and trophic ecology

Efecto de la cladosporiosis en la composición y compuestos aromáticos de vinos tintos

High incidences of Cladosporium rot frequently occur (over 50% infected berries per clusters) in delayed harvests in Cabernet Sauvignon and other red cultivars of Vitis vinifera in Chile. The objective of this study was to determine the effect of Cladosporium rot (Cladosporium cladosporioides and C. herbarum) on composition and aroma of red wine. Cabernet Sauvignon and Carménère wines made with 50% of Cladosporium rot infected grapes (CRG) were characterized and compared with wines made identically with apparently healthy grapes (AHG). Wine composition, color, and aroma were determined and the wines were subjected to sensory evaluation. Differences in volatile acidity, residual sugar, anthocyanins, color hue, and tannins between CRG wines and AHG wines of both Cabernet Sauvignon and Carménère were significant (pEn Chile, en cosechas retrasadas de Cabernet Sauvignon y otros cultivares tintos de Vitis vinifera ocurre con frecuencia una alta incidencia de cladosporiosis (> 50% de las bayas afectadas por racimo). El objetivo de este estudio fue determinar el efecto de la cladosporiosis (Cladosporium cladosporioides y C. herbarum) sobre la composición y aroma del vino tinto. Se elaboraron vinos Cabernet Sauvignon y Carménère con 50% de bayas infectadas con cladosporiosis (CRG), se caracterizaron y se compararon con vinos preparados de forma idéntica pero con bayas aparentemente sanas (AHG). Se determinó la composición, color y aroma de los vinos y se evaluaron sensorialmente. Se encontraron diferencias significativas (

Effect of Cladosporium rot on the composition and aromatic compounds of red wine

High incidences of Cladosporium rot frequently occur (over 50% infected berries per clusters) in delayed harvests in Cabernet Sauvignon and other red cultivars of Vitis vinifera in Chile. The objective of this study was to determine the effect of Cladosporium rot (Cladosporium cladosporioides and C. herbarum) on composition and aroma of red wine. Cabernet Sauvignon and Carménère wines made with 50% of Cladosporium rot infected grapes (CRG) were characterized and compared with wines made identically with apparently healthy grapes (AHG). Wine composition, color, and aroma were determined and the wines were subjected to sensory evaluation. Differences in volatile acidity, residual sugar, anthocyanins, color hue, and tannins between CRG wines and AHG wines of both Cabernet Sauvignon and Carménère were significant (