Volatile composition and sensory properties of wines from vineyards affected by iron chlorosis

Aroma profiling of Shine Muscat grape provides detailed insights into the regulatory effect of gibberellic acid and N-(2-chloro-4-pyridinyl)-N-phenylurea applications on aroma quality

As plant growth regulators, gibberellic acid (GA₃) and CPPU [forchlorfenuron, N-(2-chloro-4-pyridinyl)-N-phenylurea] are widely used in the production of table grapes. However, how these compounds regulate the aroma quality remains unclear. By measuring free and bound aroma compounds in Shine Muscat grapes from eight groups during whole growth period, GA₃ and CPPU were both found to significantly promote the synthesis of acyclic monoterpenes and (E)-2-hexenal, and double applications were found to further increase the aroma compound contents. On the other hand, GA₃ and CPPU obviously promoted the expansion of berries, and the effect of promoting the synthesis of aroma compounds was largely diminished. In conclusion, free compound concentrations in berry were almost unaffected by GA₃ and CPPU. From the perspective of aroma compounds, a highly concerted interplay was observed for terpenes, and bound compounds exhibited higher correlations than those of free compounds. In addition, 17 compounds could be used as markers that indicated the developmental timing of berries.

Impact of Ageing on Ultrasound-Treated Lees on Volatile Composition and Sensory Properties of Red Sparkling Base Wine

Ageing on lees can be a good technique to enhance the quality of red sparkling base wines. Ultrasound treatment of the lees, prior to addition to the wine, can improve the releasing of their components into the wine. This study carries out a four month ageing on lees of a red sparkling base wine by the addition of lees sonicated at different amplitude levels: 30%, 60% and 90% for 10 min. The ageing on ultrasound-treated lees improved the quality of the red base wine, with a greater impact the higher the amplitude of the applied ultrasound. Sonicated lees at an amplitude of 90% enlarged the concentration of neutral polysaccharides in the wine and reduced its astringency, which was evaluated chemically. Furthermore, this treatment enhanced the concentration of some volatile compounds in the wine, mainly acetates, esters and terpenes with floral and fruity aromatic notes. This trend was also found for some fused alcohols, contributing to the aromatic complexity of wines, as well as for 2-phenylethanol, an alcohol with a rose-like aroma, and also for C6-alcohols with a green-herbaceous aroma. The results indicate that ultrasonication is a promising tool to increase the benefits of ageing on lees on the quality of red sparkling base wines.

A colourimetric fluorescent probe for the sensitive detection of total iron in wine

As the iron content of wine affects the wine quality, a highly selective and simple detection method is needed to detect the iron content in wine. A colourimetric fluorescent probe (BTBAP probe) for the detection of total iron in wine was developed. The quantitative range of Fe^2+/3+ content detected with the probe was 0 to 200 μM with a limit of detection (LOD) of 1.16 μM. After 10 min of Fe^2+/3+ addition, the luminescence intensity of the BTBAP probe solution gradually decreased with increasing Fe^2+/3+ concentration. Moreover, the B and G values of the luminescence photos were linearly related to the concentration of Fe^2+/3+ (0-200 μM). BTBAP probe was successfully applied for rapid determination of the Fe^2+/3+ concentration of wine. This work demonstrates that BTBAP probe is an excellent tool for rapid determination of the total iron content of wine using only a smartphone and no other professional equipment.

Multi-objective evaluation of freshly distilled brandy: Characterisation and distribution patterns of key odour-active compounds

The characterisation and distribution patterns of key odour-active compounds in head, heart1, heart2, tail, and stillage cuts of freshly distilled brandy were investigated by gas chromatography–olfactometry-mass spectrometry coupled with aroma extract dilution analysis (AEDA) and chemometrics analysis. Results from AEDA showed that there were 50, 61, 48, 25, and 18 odour-active compounds in the head, heart1, heart2, tail, and stillage cuts, respectively. Besides, 19, 22, 11, 5, and 4 quantified compounds with odour activity values ≥ 1, respectively, were considered to be potential contributors to the aroma profile of different distillation cuts. Especially, the chemometrics analysis illustrated the heart1 fraction was characterized by 3-methylbutanol, ethyl hexanoate, 1-hexanol, ethyl octanoate, benzaldehyde, ethyl decanoate, and 2-phenylethyl acetate; (E)-hex-3-en-1-ol, (Z)-hex-3-en-1-ol, and 2-phenylethyl acetate greatly contributed to the characteristics of the heart2 cut. Furthermore, different volatile compounds with a variety of boiling points and solubilities followed diverse distillation rules during the second distillation. Our findings may provide a rational basis for concentrating more pleasant aroma components contributing to brandy.

Use of Multivariate Statistics in the Processing of Data on Wine Volatile Compounds Obtained by HS-SPME-GC-MS

This review takes a snapshot of the main multivariate statistical techniques and methods used to process data on the concentrations of wine volatile molecules extracted by means of solid phase micro-extraction and analyzed using GC-MS. Hypothesis test, exploratory analysis, regression models, and unsupervised and supervised pattern recognition methods are illustrated and discussed. Several applications in the wine volatolomic sector are described to highlight different interactions among the various matrix components and volatiles. In addition, the use of Artificial Intelligence-based methods is discussed as an innovative class of methods for validating wine varietal authenticity and geographical traceability.