Читать книгу Wine Faults and Flaws - Keith Grainger - Страница 14

The origins of wine production date back 8000 years, but the advances in the science and technology of production since World War II have outstripped those of the previous 79 centuries. There have been huge changes in the methods and improvements in standards of viticulture, although the reliance upon chemical fertilisers, pesticides, and herbicides that began in the 1960s declined only recently and was certainly both damaging to the environment and wine quality. The recent advent of geolocating and remote and proximal sensing and soil mapping, so‐called ‘precision viticulture’, and techniques to determine the hydric stress of vines have enabled growers to fine tune site‐specific management practices, including the precise addition of desirable nutrients and, where permitted, measured quantities of adjusted irrigation water to individual vineyard blocks, or even precise parts of blocks.

In the winery there have been numerous advances in equipment design and quality, and winemaking procedures. Some of the most important of these are:

 Grape sorting and selection systems to exclude unripe, rotten, or damaged fruit: spectacular innovations have been made in the technology of sorting equipment in the last 15 years, including the use of sophisticated optical sorters;

 The widespread utilisation from the 1970s of temperature‐controlled fermentation vessels (usually constructed of easily cleanable AISI 316 or 304 grade stainless steel), although the move today is ‘back’ to vats made of wood or concrete;

 Development of numerous individual strains of cultured yeasts aiding the control of fermentations and development of required flavours;

 A detailed understanding of malolactic fermentation (MLF) and the development of suitable inoculums for use when deemed necessary;

 The utilisation of a wider range of extraction techniques including pre‐fermentation cold soaks, rack, and return (délestage), flash détente and thermo détente;

 The use of gases namely carbon dioxide, nitrogen, and argon, primarily to avoid unwanted oxidation;

 The development of programmable enclosed pneumatic presses that can be gas‐flushed;

 The utilisation of in‐tank micro‐oxygenation, particularly for inexpensive red wines, that helps polymerise long‐chain tannins and is a valuable tool if costly barrel ageing is not to take place;

 Pre‐bottling cold stabilisation, often also using the ‘contact process’, to precipitate crystals of potassium bi‐tartrate or calcium tartrate. Alternatively, membrane electrodialysis may now be employed for this purpose;

 The availability of systems employing membrane technology, for must and wine correction, and filtration, including front end microfiltration (MF), cross‐flow (tangential) MF, ultrafiltration (UF), reverse osmosis (RO), and pervaporation;

 the improvement in cork closure quality, particularly regarding the cleansing of corks of 2,4,6‐trichloroanisole (TCA), and the introduction of effective alternative closures, including screw‐caps and synthetic closures with determined oxygen transmission rates (OTRs).

Of course, small‐ and medium‐scale producers, many of whom are focussed upon the individuality and quality of their wines, may choose not to utilise ‘advanced’ techniques in the vineyard or winery, including oenological additives, processing aids, or sophisticated (and expensive) technical equipment.