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Monday, 04 April 2011 17:45

Wine Industry

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Adapted from 3rd edition, “Encyclopaedia of Occupational Health and Safety”.

Wine is produced from grapes. The ripe grape, when crushed, yields the must which, by total or partial and normal fermentation, turns into wine. During fermentation, first rapid and turbulent, then gradually slowing down, sugar is transformed into alcohol and carbon dioxide. Many elements contained in the grapes remain in the drink. The various phases of activity in the production of wine from grapes include wine-making, storage and bottling.

Wine-making

Wine-making involves a variety of activities carried out by a variety of methods ranging from traditional “farm production” to modern industrial production. The ancient method of pressing the grapes, in which the harvesters trod during the night the grapes they had gathered during the day, is less and less seen in modern wine-making. Wine is now produced in installations belonging to groups of farmers or to commercial firms, using techniques that produce a more uniform type of wine and reduce the risk of spoilage, especially that which arises from acidification which transforms the wine into vinegar.

On arrival at the cellars, the grapes are crushed in simple mills or large machines, such as centrifugal crushers, by rollers or in other ways. These processes always involve mechanical risks and noise for the entire period during which large quantities of must is being handled. The crushed mass is then transferred to large reservoirs, by pumping or other procedures, where it will be pressed to separate the juice from the skins and stalks. The must is then transferred to fermenting vessels. On completion of fermentation, the wine is drawn off from the dregs and poured into storage bins or tanks. Extraneous matter and impurities are removed by filters. Diatomaceous earth has replaced asbestos as a filter agent in some countries, such as the United States. Larger foreign matter may be removed by centrifuges.

The quality of the wine can be improved by refrigeration using continuous-flow refrigerators and double-jacketed cooling tanks. In these operations, exposure to vapours and gases released during the various stages of the process—particularly straining, fermentation and the use of disinfectants and other products intended to guarantee the hygienic condition and quality of the wine—must be borne in mind. Refrigerant gases such as ammonia may cause toxic and explosive risks, and adequate ventilation and strict maintenance to prevent leakage are essential. Automatic leak detection and respiratory protective equipment, frequently tested, should be available for emergencies. There are also the common risks due to wet and slippery floors, the disorder characteristic of seasonal activities and the quality of illumination and ventilation (the rooms where the wine is prepared are often also used for storage and are designed to maintain a uniform, relatively low temperature).

Particularly significant are the risks of asphyxiation from the vapours of alcohol and the carbon dioxide released by the fermentation process, especially when the liquids are transported and decanted into reservoirs or confined spaces where ventilation is inadequate.

Certain other harmful substances are used in wine-making. Metabisulphite in concentrated solution is irritating to the skin and the mucous membrane; tartaric acid, which is considered non-toxic, can be slightly irritating in very concentrated solutions; sulphur dioxide provokes an intense irritation of the eyes and the respiratory tract; tannins can dry a worker’s skin and make it lose pigmentation; the use of disinfectants and detergents for the washing of storage tanks cause dermatitis; and potassium bitartarate, ascorbic acid, proteolytic enzymes and so on, which may be used in the preparation of alcoholic beverages, can cause diarrhoea or allergic reactions.

When work processes are modernized, workers may need support and assistance in order to adapt. Large production cellars should consider ergonomic principles in the choice of the equipment for such installations. Crushers and presses should have easy access in order to facilitate pouring the grapes and the residues. Whenever possible, suitable pumps should be installed, which should be easy to inspect and should have a solid foundation in order not to cause any obstruction, high noise levels and vibrations.

The general organization of the production cellar should be such that no unnecessary risks are caused and that risks should not spread to other areas; ventilation should conform to standards; temperature control may be necessary; compressors, condensers, electrical equipment and so on must be installed so as to obviate all possible risks. Because of the humidity of several processes, protecting electrical equipment is necessary and, where possible, low voltages should be used, especially for portable equipment and inspection lamps. Ground fault circuit interrupters should be installed where necessary. Electrical equipment in the vicinity of distillation plants should be of flameproof construction.

Wooden vats are decreasingly common, though they can occasionaly be found in small cellars for farm production. In modern wine-making, vats are lined with glass or stainless steel for sanitary and control reasons; lined reinforced concrete and, sometimes, plastics are also used. Vats must have the proper dimensions and be adequately resistant to allow fermentation and decanting (right down to the dregs), to hold the volume of reserves as long as necessary and to allow for easy exchange of their contents, should it prove to be necessary. Cleaning of containers involves especially high risks, and a confined-space programme should be in effect: the gas should be dispelled by mobile ventilators before containers are entered, and safety belts and life-lines and respiratory protective equipment should be worn. A competent worker should be stationed outside to supervise and rescue workers inside, if necessary. See the box on confined spaces for more information.

Wine Storage

Storage involves not only the keeping of large volumes of liquid but also a number of activities such as cleaning and disinfecting the tanks or casks; their maintenance and conservation; application of sulphur dioxide, ascorbic acid, tartaric acid, inert gases, tannins and albumins; and other additional processes, such as mixing, glueing, filtering, centrifugation and so on. Some treatments of wine involve the use of heat and cold to destroy yeast and bacteria; the utilization of carbon and other deodorizers; the application of CO2, and so on. As an example of this type of installation we may refer to the system of instantaneous refrigeration, for the stabilization of wines at a temperature near the freezing point, which facilitates the elimination of colloids, microbes and other products such as potassium bitartarate, which provokes precipitation in the bottles. It is obvious that these installations imply risks that formerly did not need to be considered in this phase of storage. Prevention is essentially based on ergonomic planning and good maintenance.

 

Wine Bottling

Wine is usually sold in glass bottles (of 1.0, 0.8, 0.75 or 0.30 l capacity); glass containers of 5 l are occasionally used. Plastic containers are not as common. In the filling plants, bottles are first cleaned and then filled, sealed and labelled. Conveyors are widely used in bottling plants.

The risks of bottling arise from the handling of glass material; these vary according to whether the bottles to be washed are new or returned, and according to the products used (water and detergents) and the techniques applied (washing by hand or mechanically or both). Bottles’ shape; how the filling must be done (ranging from manual methods to sophisticated filling machines which can also introduce carbon dioxide); the process of corking; the more or less complicated system of stacking, or placing into boxes or crates after labelling; and other final touches determine the risks.

The risks involved are those which generally correspond to the filling of containers with liquids. The hands are constantly wet; if the bottles break, the projection of glass particles and liquid can cause injuries. The effort required to transport them once they are packed in boxes (usually by dozens) could be eliminated at least partially by mechanization. See also the article “Soft drink bottling and canning”.

Acknowledgments: The author would like to thank the Junta Nacional dos Vinhos (Lisbon) for their advice on technical aspects.

 

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