Analysis of the oenological potentials of different oak forests in Hungary

Filtration is a critical step in ensuring the clarity and microbial stability of wine prior to bottling. However the process of filtering potentially reduces red wine quality by removing some of the macromolecules that contribute to the texture of the wine. Commercial red wines, Cabernet Sauvignon (CAS) and Shiraz (SHZ), of two vintages and two grades (premium grade wines from the older vintage: CAS13 and SHZ13; and standard grade wines from a younger vintage: CAS14 and SHZ14) were filtered through industrial-scale commercial filtration units prior to bottling. Samples were taken before and after cross-flow filtration, lenticular filters, 0.65 µm and 0.45 µm pore size nylon membrane filters. The concentration and composition of macromolecules, including tannins and polysaccharides, were measured in all samples as well as particle size distribution and wine colour.

The above-ground parts of plants, which constitute the phyllosphere, have long been considered devoid of bacteria and fungi, at least in their internal tissues and microbial presence there was long considered a sign of disease. However, recent studies have shown that plants harbour complex bacterial communities, the so-called “microbiome”[1]. We are only beginning to unravel the origin of these bacterial plant inhabitants, their community structure and their roles, which in analogy to the gut microbiome, are likely to be of essential nature. Among their multifaceted metabolic possibilities, bacteria have been recently demonstrated to emit a wide range of volatile organic compounds (VOCs), which can greatly impact the growth and development of both the plant and its disease-causing agents.

From the standpoint of wine aroma oxidation there are two effects observed: aroma degradation of oxygen sensitive compounds (polyfunctional mercaptans) and the appearance of new substances with high aromatic power (acetaldehyde, methional, phenylacetaldehyde, sotolon, alkenals, isobutanal and 2, 3-metylbutanals) (1-5). According to our experience, Strecker aldehydes are compounds with highest sensory relevance in the oxidative degradation of many wines (5-7).

For characterization, sensory designing and authentication rapid analytical technologies have become available. Some, like Proton Transfer Reaction Mass Spectrometry allow a rapid spectrum of the volatile compounds of wines. Combined with chemometrics wines can be characterized. The same approach can be used to calculate the results of virtual mixtures and allow formulation of constant quality blends. Other new techniques and portable devices based on spectroscopy allow measurements on production sites and in grocery stores, even for the smart consumer. We will present some examples of the application of these techniques for authentication of wines, both in the laboratory and on site.

An intelligent packaging might, among others, provide information and allow monitoring of the quality of the packed product or its surrounding environment. A recent project on micro-flow wine bottles closed with aluminium screw cap and tightness liner, highlighted the importance of monitoring the internal overpressure continuously, in real-time and at least for 72 hours, since the internal pressure on the tightness liner and the micro-flow are related. Real-time and continuous measurements are not the standard methods of measurement of the overpressure, yet. The most used equipment for the determination of the pressure in wine bottle is the aphrometer, a destructive device that supplies a single value of pressure.