The harvest is the climax of all winemakers’ lives. Late and some sleepless nights typify this time of the year. Grapes must be monitored, juice prepared for fermentation, yeast cultures prepared and the alcoholic fermentation must be monitored and managed. The birth of a young wine introduces another vintage which will be drunk some or other time. The rest of the year can however not be neglected to ensure that the results of the harvest are maintained and the necessary preparations for the next vintage are implemented timeously.
The end of harvest is typified by the completion of certain cellar practices and the production of the young wine. It comprises amongst other the last pressing of red skins, the racking of white wines, which has undergone sur lie and the completion or initiation of malolactic fermentation (MLF). If a co-inoculant was not used, the latter can continue until after harvest, especially when the temperature starts to decrease. It can even in some cases continue until the next spring, before it is completed. Wines are in particular exposed to oxidation between alcoholic fermentation and the completion of malolactic fermentation. Sulphur dioxide adjustments can also not be made, before MLF is completed. It is consequently even desirable to heat wines to ensure that the desirable Oenococcus species complete MLF timeously. After the MLF completion, a high sulphur dioxide addition instead of a few low ones can be made.
While waiting for the completion of MLF, the time can be utilised advantageously to have a post-mortem discussion on the finished vintage. All employees should be involved, before they leave for their deserved holidays. This discussion should not address the winemaking, but rather focus on the processes and equipment that were used. Seeing that it is too early to evaluate the success of the winemaking, aspects like staff scheduling, equipment needs and cellar capacity must rather be discussed. Resolutions must be noted to monitor their execution.
The terms cleaning, sanitation, disinfection and sterilisation are often used as if they are the same action. It is however individually defined according to the percentage of killing potential against harmful micro-organisms. Cleaning has no microbiological definition, but it comprises the removal of visible debris in the cellar, which can serve as an incubation base for micro-organisms. Sanitation implies that 99,9% of all bacteria is killed, but the citing does never include viruses or moulds. Disinfection implies that 99,999% of all micro-organisms are killed and the killing percentage of sterilisation is 99,9999%. Different sterilisation methods, like dry or wet heat, filtration, 70% ethanol solution or UV light, can be used in wine cellars. The main focus in wine cellars is usually on cleaning and sanitation. Disinfection and sterilisation are seen as being the same. It is essential that all equipment used during the harvest, is cleaned and sanitised effectively as soon as possible after the harvest. This will prevent the build-up of a population of undesirable micro-organisms before the next harvest. If undesirable micro-organisms, like Brettanomyces and Lactobacillus, have established a population in a cellar it will be difficult to eliminate them and instead they should only be managed. If cellars do their own packaging, the effective cleaning and sterilisation of bottling equipment will obviously play an important role to ensure that the microbiological stability of wine is maintained (Philips, 2019).
As a result of the time limitation and production processes of harvest time, it is ideal that cellar equipment function optimally and full-time without any breakdowns during that period. In order to realise this, cellars can apply a preventative maintenance programme after the harvest to identify and prevent potential equipment breakdowns. If this is not done, maintenance can evolve into crisis management, consisting of repairs together with interruptions.
Some cellar equipment, like sorting tables, crushers, destemmers and presses, are only used during the harvest. If cellars plan to use current equipment again or adjust it instead of buying new equipment, the adjustments and/or purchasing must be done timeously.
Maintenance practices can vary between cellars. Reactive maintenance is applied after the breakdown of equipment and is the most expensive way of maintenance. Preventative maintenance prevents the breakage of equipment. Predictive maintenance schedule preventative maintenance according to the required functioning of equipment between breakages. The latter includes cleaning, lubrication, inspection and testing (Theron, 2017).
Cleaning and sanitation of harvest equipment is essential.
Philips, C., 2019. Time flies when you’re making wine. Wine Business Monthly, January 2019: 152 – 158.
Theron, C., 2017. Maintenance of cellar equipment before and after harvest. WineLand, December 2017.