Chapter 14

Winery Cleaning and Sanitation

Microbial Monitoring in the Winery

In order to manage the cleaning and sanitation program of a winery, it is essential to test for the presence of microbes and monitor their status. It is recommended that the stage between alcoholic fermentation and malolactic fermentation during maturation until the blending of wines and the stage prior to bottling, are seen as the three most important critical control points during winemaking.

Microscopic Observation of Wine Spoilage Organisms

The simplest way to monitor microbes is by making direct observations of the wine using a microscope capable of 1000x magnification. The microscope is a very powerful aid to the winemaker because, with a good microscope and a little experience, it is possible to instantaneously detect any substantial population of microbes in the wine.

Viable Plating of Wine Microorganisms

Contrary to direct microscopic observation, where the cells can actually be observed, viable culture plating relies on the ability of cells to reproduce, resulting in a visible colony on the surface of the nutrient media.

Spread Plate Technique

Spread plating is useful if there is a high microbial population. Plating is a procedure that is usually well within the capabilities of most small wineries and should be for all larger ones (Figure 14.7).

Membrane Filtration Technique

Membrane filtration is useful when dealing with wines that have a very low level of viable microorganisms. This method uses a vacuum to pull a large volume of wine through a small membrane filter that retains the cells, thus concentrating the bacteria or yeast.

ATP Bioluminescence Testing in the Winery

In recent years, many large and mid-size wineries have adopted a technique referred to ATP bioluminescence. Adenosine triphosphate (ATP) is found in all living or once living biological cells and is used as a proxy of microbial contamination. Adenosine triphosphate bioluminescence does not identify specific microorganisms that could be contaminants, but it does provide a rapid analytical indication of the effectiveness of cleaning and sanitizing practices at specific locations.

How to Test for ATP

Adenosine triphosphate testing systems contain 3 main parts - sample collection swabs, a luminometer, and software to analyze the data output. Sample collection swabs are used to swab down surfaces or collect water samples and inserting the swab into a luminometer that quickly provides a reading (Figure 14.8). These pen sized swabs contain bioluminescent reagents that react with the ATP in the sample to emit light.

ATP Test Results

There are generally two results given, a number in RLU and whether this quantification indicates a PASS or a FAIL to the sanitation process. This PASS or FAIL determination (a specific number of RLUs) is somewhat arbitrary.

Scope of the Bioluminescence Method

Although ATP swabbing gives us a good indication at the total quantity of cells left behind after sanitation, this type of assay only signals either the presence or absence of cells.

Polymerase Chain Reaction Testing in the Winery

A new emerging technology is real-time quantitative polymerase chain reaction (PCR) analysis. Results can be expressed on the same day, and it is possible to perform a simultaneous quantification of more than one pathogen in a single assay. Overall, it allows for a quicker analysis that is just as sensitive as traditional PCR.

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