Winery hygiene

Why is cellar hygiene and the control of microbial growth important?

• critical in the process of eliminating uncontrolled growth

• irrespective to the scale of winery

• all cellar staff responsible

What is cleaning?

The removal of extraneous or unwanted material or any matter, solid or liquid that is foreign to a particular surface

What is sanitisation?

The maintenance of unwanted matter or microorganisms at a level that prevents potential negative impacts on quality

What is sterilisation?

The complete elimination of microorganisms

What is involved in the control of microorganisms?

• object to minimise numbers or completely eliminate

• irrespective of method used, control is more effective when there are fewer cells, when cells are in exponential growth or injured

• bacteria, yeast, mould, phage and viruses differ in sensitivity to control methods (strain or species can make a difference)

How do you achieve the objective of minimising numbers or completely eliminating microorganisms?

1. control access of microorganisms to grapes and wine

2. physical removal

3. prevent or reduce growth

4. kill cells or spore present

How does one control access?

• cleaning & sanitisation key

• impossible to prevent access completely, therefore, reduce the initial load

What factors are important to consider in cleaning and sanitisation?

• winery design

• equipment

• training of staff

• effectiveness of cleaning and sanitation

What aspects of winery design might influence microbiological control?

• inside and outside must be considered

• equipment must be positioned to allow easy access for cleaning

• winery floor should be sloped and resistant to sanitising chemicals

• equipment should be graded as potential sources of contamination: incorporated into quality management programs

In terms of equipment grading and drainage facilities, what has the highest to the lowest risk?

Grape

Bin

Pumps

Fermenters

In terms of equipment grading and composition of liquid in contact with equipment, what has the highest to the lowest risk?

grape

juice

table wine

fortified wine

In terms of equipment grading and contact time, what has the highest to the lowest risk?

long term (tanks)

short term (crusher, press)

What is involved in cellar hygiene and effective sanitation?

• removal of gross contamination: dried grape matter, slat precipitates

• dried matter reduces sanitation effectiveness by:

  • providing a physical barrier to subsequent sanitation

  • react chemically with sanitisers

  • acts as a substrate for further microbial growth

What are the basic sanitation principles that should be implemented in a winery?

1. winery kept free of refuse inside & out

2. equipment arranged in orderly way, work areas free of clutter

3. entire winery cleaned on regular scheduled basis

4. winery protected against; bacteria, yeast, moulds, insects, rodents

5. premises, equipment & cooperage inspected monthly

The effectiveness of hygiene practices is influenced by?

• presence of organic matter - i.e., grape skins, lees

• temp, some practices/chemicals may have an optimum temp range

• physical contact with microorganisms

• time of conduct

• conc of chemical agents used

• pH

• types of organisms

What should cleaning practices involve in the winery?

1. pre-rinse to remove large debris, to wet area & increase effectiveness of cleaning agent

2. apply cleaning agent for removal through effective wetting & penetrating properties

3. inspect for cleanliness

4. apply sanitiser - chem/physical

5. wash with water to rinse

What cleaning compounds are commonly used in wineries?

alkaline compounds most common

Strong: sodium hydroxide - CAUSTIC SODA

0.5% w/v solution is pH 12.7

Heavy duty sodium carbonate SODA ASH

0.5% w/v solution is pH 11.3

REQUIRES ACID & WATER RINSE

CAN REUSE SOLUTIONS IF MONITOR PH - e.g., dump once pH <8

What is standard winery sanitation practice?

1. wash excess organic material off with water

2. 0.5-2% (w/v) caustic/soda ash

3. 0.5-2% (w/v) citric acid

4. rinse with water

Sorbic acid can also be used for sanitation, what are its properties/limitations?

• effective in protecting wines against yeast growth

• can only be used post MLF

• commonly used in cask wines as they generally have a larger shelf life

There are other cleaning compounds, what are some of the targeted specific uses of these?

• biofilm removal

• oak barrel cleaning

• no rinsing

• more WHS friendly

• cross flow membrane cleaning

What are the desirable properties of chemical sanitising agents?

• microbial destruction, broad spectrum

• effective in presence of organic matter, detergent, water hardness and pH

• good cleaning properties

• nontoxic, nonirritating

• water soluble, low odour, ease of use

• stability in concentrated & use dilution

provide a scrubbing action to increase effectiveness of cleaning action

What are some properties of chlorine based sanitising agents used in the wine industry?

• antimicrobial action via oxidation, effective against a wide range of organisms

• relatively common in the past

• less effective in presence of organic materials

• prolonged contact with rubber and certain plastics may generate chlorophenols (toxic)

strongly implicated in trichloranisole problems (CORK TAINT), no longer recommended

What are some properties of quats (quaternary ammonium compounds) sanitising agents used in the wine industry?

• alternative to halogens

• both antimicrobial & detergent properties

• antimicrobial activity via denaturation of proteins & destabilisation of membrane function

• more effective at low pH & higher temp, not effected by organic matter

• highly stable, non corrosive, non toxic with strong residual activity on surfaces

• expensive and not effective abasing all organisms (gram negative)

• external surfaces only, as film forming

What are some physical agents of microbial control in wine?

• filtration - depth/membrane filtration removes organisms & nutrients

• heat - reduces or eliminates organisms (pasteurisation)

• Others - ultrasonics, high pressure, dry ice

What is involved in the control by filtration?

• physical removal of microbes

• effective only for liquids

• limited physiochemical changes

• large variety of methods available - coarse to sterile

• centrifugation also can be used

What is involved in the control by heat?

• microbes range in heat resistance (spores in particular are resistant)

• effective ness influenced by:

  • presence of contaminates (organic matter)

  • what is being traded (tank vs wine)

  • temp and time