Modification of the polyphenolic and aromatic fractions of red wines aged on lees assisted with ultrasound

Application of white wine lees for promoting lactic acid bacteria growth and malolactic fermentation in wine

In the context of ecological transition, the use of wine by-products for industrial applications is a major challenge. Wine lees, the second wine by-product in terms of quantity, represent a source of nutrients that can be used for stimulating the growth of microorganisms. Here, white wine lees were used as a stimulating agent for the growth of wine lactic acid bacteria (LAB) and to promote wine malolactic fermentation (MLF) driven out by Oenococcus oeni. By adding freeze-dried wine lees to wines under different conditions - including different wine lees at different concentrations and different O. oeni strains at various initial populations - it was observed that wine lees can enhance the growth of LAB and reduce the duration of MLF. The chemical composition of wines was also evaluated, proving that wine lees do not compromise the quality of the wines. In addition, wine lees did not seem to promote the growth of spoilage microorganisms like as Brettanomyces bruxellensis. Altogether, this work reports the possibility of recovering the lees of white wine to obtain a product favoring the MLF of red wines. More general, we propose a recycling strategy of wine by-products to obtain new products for winemaking.

Characterization of white and rosé sparkling wine lees surface volatiles

Cava is a sparkling wine that requires a second fermentation in the bottle. Its volatile fraction is conditioned by different parameters (grape, vinification process, fermentative yeast, and aging time). During the autolysis process, yeasts release compounds into the wine, but lees can adsorb certain compounds on their surface. Therefore, the aim of this work was to characterize different white and rosé Cavas, and their lees. For this, white Cavas (CGR1: 40 months; CR1: 16 months) and rosé Cavas (CRR1: multivarietal coupage; CRR2: monovarietal; both 20 months) were studied. Once disgorged, lees were freeze-dried (L-CGR1, L-CR1, L-CRR1 and L-CRR2). In addition, lees waste from the winery were collected. pH, total polyphenol index (TPI) and colour intensity (CI) of Cavas and lees were determined. The volatile fraction was analysed by Head-Space Solid Phase Microextraction followed by gas chromatography coupled to mass spectrometry. Lees showed higher values than their respective Cavas for TPI and CI, especially in the case of the L-CGR1. Most of the volatiles were identified both in Cavas and their lees, esters being the main compounds. Therefore, lees can retain phenolic and volatile compounds on their surface, which could be of interest as a new ingredient in the food industry.

Effect of organic compounds on cognac sensory profile

Introduction. The present research featured the effect of carbonyls, phenols, furans, fatty alcohols, ethers, and other chemical compounds on the sensory properties of cognac distillates of different ages. The research objective was to identify additional criteria of sensory evaluation by measuring the effect of various compounds on perception intensity. Study objects and methods. The study featured cognac samples of different ages. The experiment involved standard methods, including high-performance liquid and gas chromatography and a mathematical analysis based on Microsoft software. Results and discussion. The content of fatty alcohols, ethers, and carbonyl compounds that formed as a result of fermentation demonstrated little change during the aging period in oak casks. A longer extraction increased the content of phenolic and furan compounds and sugars. The content of terpene compounds decreased due to their high lability. The study revealed the effect of organic compounds on taste descriptors. The article introduces multivariate equations that calculate the dependences of the descriptor intensity on the content of organic compounds. A correlation and regression analysis revealed that phenolic compounds had a significant effect on the taste formation of cognac samples, depending on the aging time. Conclusion. Organic compounds proved to affect the taste profiles of cognac samples of different ages, as well as sensory evaluation descriptors.

Reactivity of flavanols: Their fate in physical food processing and recent advances in their analysis by depolymerization

Flavanols, a subgroup of polyphenols, are secondary metabolites with antioxidant properties naturally produced in various plants (e.g., green tea, cocoa, grapes, and apples); they are a major polyphenol class in human foods and beverages, and have recognized effect on maintaining human health. Therefore, it is necessary to evaluate their changes (i.e., oxidation, polymerization, degradation, and epimerization) during various physical processing (i.e., heating, drying, mechanical shearing, high-pressure, ultrasound, and radiation) to improve the nutritional value of food products. However, the roles of flavanols, in particular for their polymerized forms, are often underestimated, for a large part because of analytical challenges: they are difficult to extract quantitatively, and their quantification demands chemical reactions. This review examines the existing data on the effects of different physical processing techniques on the content of flavanols and highlights the changes in epimerization and degree of polymerization, as well as some of the latest acidolysis methods for proanthocyanidin characterization and quantification. More and more evidence show that physical processing can affect content but also modify the structure of flavanols by promoting a series of internal reactions. The most important reactivity of flavanols in processing includes oxidative coupling and rearrangements, chain cleavage, structural rearrangements (e.g., polymerization, degradation, and epimerization), and addition to other macromolecules, that is, proteins and polysaccharides. Some acidolysis methods for the analysis of polymeric proanthocyanidins have been updated, which has contributed to complete analysis of proanthocyanidin structures in particular regarding their proportion of A-type proanthocyanidins and their degree of polymerization in various plants. However, future research is also needed to better extract and characterize high-polymer proanthocyanidins, whether in their native or modified forms.

Use of ultrasound at a pilot scale to accelerate the ageing of sherry vinegar

In the present work, the accelerated ageing process of sherry vinegar has been studied at pilot scale by means of the joint application of ultrasound, micro-oxygenation and wood chips (American oak, French oak and Spanish oak). The CIELab parameters have been studied as well as the polyphenolic and volatile content of the aged vinegar samples. Vinegars aged with American oak presented different chromatic characteristics to those aged with French and Spanish oak and a lower polyphenolic and volatile content than the latter ones. On the other hand, Spanish oak generated vinegars with a higher content of volatile compounds and an intermediate polyphenolic profile between those obtained using French and American oak. In addition, the use of ultrasound for a period between 4 and 21 days, generated vinegars with similar characteristics to others that were aged in the traditional way for between 2 and 6 months. It has been demonstrated that the use of ultrasound, combined with micro-oxygenation and chip addition, is a technique which can accelerate the ageing process of vinegars at a pilot scale, so it could be a viable alternative to obtain sherry vinegars aged in a shorter time.