Keeping it clean – part 1

We only want wine in our wine, so winery hygiene is essential for producing a quality product, avoiding contamination and unwanted taints. Winery hygiene is also crucial for the health and safety of both consumers and winery staff. Wineries are also tourist destinations, so clean premises make a good impression! It’s a big topic and this is part one of a series of articles on cleaning and sanitising from Vineyard.

Why clean and sanitise the winery? 

Wine is essentially a food product, so the winery or producer has an obligation to create wine that meets relevant legislation and is safe for consumption. According to the WineGB website, “UK wine law is based on European Union law and is enforced by the Wine Standards Branch (WSB) of the Food Standards Agency (FSA).” Further information for producers can be found via links from the members’ area of the website, www.winegb.co.uk. The Wine Standards team’s enforcement covers the safety, quality, authenticity and correct labelling of wine products, in vineyards, wineries and bottling plants – and further information can be found at www.food.gov.uk/business-guidance/wine-regulation. However, very little of the legislation relates directly to cleaning and sanitising, only to the consequences of poor hygiene. Campden BRI publish ‘Cleaning and disinfection of food factories: a practical guide’, which can be found on their website.

Campden BRI is the UK’s main accredited laboratory providing scientific and technical analysis of wine along with regulatory support. Rachel Rees, Wine & Spirits Technical Manager leads the laboratory team at Campden BRI, so is aware of all the issues that arrive in the lab. “In fact, most of the contamination that we see is due to poor cleaning of the bottling line equipment after filling the previous product – it may not be a risk to health, but the wine is contaminated,” explained Rachel. 

“Wine is classed as a food product and there are regulations to be followed on good hygiene for food production. Spoilage organisms that can affect the wine are bacteria and yeasts, which commonly come into the winery from the vineyard, particularly on picking crates, but also from second-hand barrels and equipment. So, anything coming into contact with the grapes, juice or wine needs to be clean and sanitised. Some wineries may want to use wild yeasts – but this still needs to be controlled,” explained Moyra Williams, Technical Sales Consultant, Holchem, a manufacturer of cleaning products for wineries and breweries.

“If purchasing second-hand barrels and winery equipment, ensure they are of a hygienic design and can be thoroughly cleaned and sanitised. Also, be aware that if equipment is not designed for winemaking it may not be so easy to clean. Tanks may have ‘shadow’ areas, nooks and crannies that can’t be reached by a spray head. Even equipment designed for winemaking may have ‘shadow areas’, such as lips under tank doors, fittings and pipework that can harbour spoilage microbes. Surfaces that are not super shiny are hard to clean and any scaling will need an acid descale – as rough surfaces are a great place to hide!” 

“All food contact surfaces should be smooth, non-porous, easily cleanable and free from irregularities such as pits, folds, poor welds or crevices. It is generally accepted that smoothness is a key requirement to cleanability,” advised Moyra. 

“A clean winery will discourage pests and reduce accidents. It’s also important to keep plant and equipment clean to avoid loss of efficiency, for example fouling in pipes will inhibit flow. Tank door rubbers need to be checked for cracking as this is another hiding place for microbes, as are floors and drains.

“Any cleaning regime has to be validated to check it is actually doing the job – never assume! For example, if a spray ball used for cleaning a tank has any blocked holes– it will not be reaching all areas. Adenosine triphosphate (ATP) swabs are a good way to check if surfaces have been sanitised in an effective hygiene monitoring regime. If ATP is present it indicates that there is a biological residue – such as spoilage organisms.

Where possible, always visually check that equipment is clean. Cleaning and sanitising are a two-stage process – cleaning to remove all soiling should be followed by a sanitisation/disinfection process. You cannot disinfect a dirty surface! Fittings from tanks also need to be cleaned before they are put into a soak bath to sanitise,” added Moyra.

Brett

“At Campden BRI we see incidences of the spoilage organism Brettanomyces (Brett), as we can analyse for one of its metabolites, 4-ethylphenol. If present, the 4-ethylphenol highlights that the wine has been in contact with Brett, and this could be from a barrel that is infected, or from a Brett contaminated wine that had previously been in the barrel,” explained Rachel.

“Brettanomyces is incredibly difficult to get rid of, every winery potentially has it,” commented Sarah Midgley, Plumpton College Wine Division lecturer and former winemaker. It’s a yeast that comes into the winery from the vineyard, on grape skins, it’s on the winery floor, in the tanks etc. It’s safer to assume that it’s all around and keep the winery as clean as possible. Wine needs to be stored properly with the correct level of SO₂, with full tanks, or if there is any space make sure the wine is covered with inert gas. I also prefer to sterile filter wine. 

“Wines that are being stored or aged are at risk; the Brett population number can climb. Reserve wines are a particular risk, so need careful monitoring and management of their free SO₂. Unfortunately, it’s not possible to get rid of Brett taint, which is often described as a dirty horse stable or hamster cage smell – but its detection does depend on an individual’s sensory threshold, and at low levels can be considered favourable by some!”

“One of the most common issues I see from poor cleaning is Brett, and wineries do not want this spoiling the finished wine. In fact, any yeast from poor cleaning and winemaking can potentially cause problems in bottle including lactic acid bacteria or acetic acid bacteria. A good hygiene regime will help reduce these risks,” added Moyra.

TCA 

“Poor winery cleaning, damp conditions, and stored damp cardboard, can result in the presence of haloanisoles in the wines,” explained Rachel. “Haloanisoles are chemically related compounds, that contain chlorine or bromine, and includes the most commonly known, trichloroanisole or TCA that migrates into the wine and results in the ‘damp cellar’, ‘wet cardboard’, ‘musty’, smell known as ‘cork taint’. Each of these haloanisoles has a similar odour but possesses different sensory thresholds. 

“The haloanisoles come from various materials, including oak products such as barrels, chips, or staves, bentonite, cork and other closures – even the wadding material in screw caps can pick-up airborne haloanisoles. The haloanisoles are created when some microorganisms are in contact with chlorinated phenolic compounds – which is why chlorinated cleaning products should not be used in a winery,” commented Rachel. 

 “Geranium taint is another undesirable or ‘faulty’ odour in wine which can be caused by using sorbic acid in the winery – which is an anti-fungal but not anti-bacterial agent. The lactic acid bacteria, used in winemaking for malolactic fermentation, can metabolise the sorbic acid producing a compound called 2-ethoxyhexa-3,5-diene which has an off-odour similar to the smell of geranium leaf,” added Rachel. 

Volatile acidity 

There may be no legal limits on Brett or TCA, but there are legal limits on the level of volatile acidity (VA) in wine. “With a dirty winery it is easy to end up with too much VA in the wine. These are acids that are apparent on the nose, rather than the palate, and include acetic acid and ethyl acetate – which is a bit like nail polish remover. Having a clean environment reduces the population numbers of the bacteria that cause VA. It’s a fault and indicator of uncleanliness,” explained Sarah.

Plumpton College’s newly appointed winemaker, Deepika Koushik, explained that, “there are also legal limits on ethyl carbamate, which can rise if urea is used in the vineyard – it’s not common but can happen. Fortunately, fermentation is a biological process and so, in most incidences, any contaminants that come into the winery from the vineyard, such as diesel, oil or pesticide residues – if harvest interval periods have not been respected – will inhibit the yeast and fermentation will not take place.” Deepika added. 

Health and safety

“In fact, with HACCP (Hazard Analysis and Critical Control Point), which is for reducing the risk of safety hazards in a food production environment, there are really not that many critical control points for wine – as fermentation is a biological process that needs the right conditions to proceed. The most critical time to ensure winery hygiene is at bottling. In practice, operators need to wear gloves and hairnets, all equipment needs to be steam cleaned to achieve sterility and usually the wine needs to be sterile filtered. Basically, the winery or bottling area needs to be cleaned to within an inch of its life!” 

“There are occasions where an older wine is considered stable, particularly if it has been aged in barrel, and the winemaker may not consider it necessary to sterile filter before bottling – but in my experience that is risky if it is a commercial wine,” Sarah added. 

“In the Plumpton College winery, every student does a risk assessment and each cleaning product has a COSHH document (Control of Substances Hazardous to Health), along with procedures for spillages. Fortunately, most of the cleaning agents we use are designed for the dairy and food industries. All the students have goggles and gloves, and for using steam, they follow strict protocols and wear heat-proof gloves. Student are taught how to use caustic soda for cleaning safely and signed off by a staff member – it’s important that they know how to use caustic soda safely as they may be required to use it when working in a winery,” added Sarah. 

“Water for cleaning has to be potable and many wineries are not on mains water, so any water used for cleaning needs testing, including for Legionella and Coliform bacteria, and in fact it is a requirement for SALSA and BRC schemes. If the water is not mains it may need be to be treated, for example with UV, or filtered,” explained Sarah. “Water hardness can also affect the formulation of cleaning products such as caustic soda,” added Moyra.