WINERY SANITATION –
BEST PRACTICES
K.C. Fugelsang, Professor Emeritus of Enology,
California State University, Fresno
WINERY SANITATION
INTRODUCTORY REMARKS:
• Microorganisms arriving on fruit, and/or already present in the winery
can not only survive, but, as conditions permit, proliferate during the
winemaking process.
• Once established, undetected/uncontrolled population `blooms' can
pose a significant threat to wine quality.
• Thus, proactive control becomes the cornerstone in minimizing the
risk of spoilage and the single most important control point is
sanitation.
• As with any processing operation, the winery should develop sitespecific Standard Operating Procedures (SOP) for sanitation.
• SOPs should include specific protocols/procedures as well as
schedules that document implementation.
• These records become part of the overall Quality Points Program.
WINERY SANITATION
DEFINITIONS:
• Sanitation: reduction of Viable Cell Number (VCN) to some predetermined low number (may/may not = 0 CFU/mL).
• May be estimated by sampling or subjective means (visual, tactile
and/or odor).
• Generally a pre-bottling goal.
• Sterilization: reduction of VCN to 0 CFU/mL.
• Winery sterilization will probably not kill mold spores or bacterial
endospores.
• Decision as to which goal is required depends upon stage in
processing and inherent wine stability.
• Many consider the concepts to be synonymous.
• Sanitation should be considered as a proactive program: the goal is to
minimize uncontrolled growth early in the process thus reducing
“pass-through” threats during later stages of processing.
WINERY SANITATION
• Considerations for Minimizing “Pass-Through” Contribution:
• Adherence to grape quality standards in terms of microbial
decomposition.
• Sanitation of harvest equipment and containers
• Reduce travel time and temperature (evening/early morning
harvest)
• Crush pad sanitation: reduce accumulations of organics (localized
population blooms).
• Regularly sanitize primary processing equipment
• Properly conducted, the sanitation program limits build–up of mineral
and organic debris (grape “bloom,” tartrates, biofilms, etc.) which
serve as reservoirs for microbial proliferation and reinfection and,
potentially, biofilm formation.
• Biofilms: impervious polysaccharide layer or film produced by
microbes in >C, N environs.
• Sanitation cycles using caustics (75°C/167°F for 30 minutes),
followed by citric acid rinse have proven successful in removing
biofilms (Parkar, et al., 2004).
WINERY SANITATION
HEALTH AND SAFETY ISSUES:
• A two-fold concern: (1) Chemical cleaners/sanitizers/sterilants are
typically strong oxidants, caustics, and/or acidic chemicals and (2)
the physical environment and processes: high pressure hot water
and/or steam, and slippery floors.
• Requires personal protective equipment (PPE) including gloves,
goggles, appropriate footwear, and waterproof aprons.
• Given the slippery properties of detergents when discharged on
floors, boots with non–skid soles should be used.
• Employee training should emphasize the importance of reading
product labels and understanding each chemical’s advantages/
limitations and safety concerns prior to use.
• Material Safety Data Sheets (MSDS) sheets containing the necessary
health and safety information for employees working with winery
chemicals should be readily available (24/7) and clearly identifiable in
prominently displayed binders, etc.
• Available from supplier or, if lost, on-line.
WINERY SANITATION
An effective sanitation program consists of at least three and, potentially,
four levels of effort and vigilance. The first step is preparation of the
surface to be sanitized/sterilized.
I. PRELIMINARY CLEANING:
• In any sanitation process, the first step is to remove as much of the
first–level or visible debris as possible.
• Accomplished either manually or by mechanical cleaning systems
such as spray balls or tank and barrel washers.
• High pressure water (600 to 1,200 lb/in2) without added chemicals
can often readily remove organics and build–up at a fraction of the
cost associated with the use of an equivalent amount of detergent
or sanitizer needed to accomplish the same goal.
• Most effective when the spray is directed at an angle to the surface
being cleaned.
• Using warm water (38oC/100oF to 43oC/109oF) in a high pressure
delivery system further improves cleaning operation while
decreasing both the amount of water used and time required for
cleaning.
WINERY SANITATION
• Although tempting, application of heat to organic materials
adhering on a surface debris should be avoided.
• The practice may serve to “cook on” the debris, thereby requiring
greater effort and costs to effect removal.
• Where stains/bloom remain, it may be necessary for workers to enter
the tank.
• Fermentors and/or storage tanks are regarded as “confined spaces,”
and as such, special health and safety regulations apply.
• These include preliminary forced-air ventilation of the tank to reduce
carbon dioxide levels followed by verification that safe levels have
been reached.
• Carbon dioxide and oxygen are easily measured by use of readily
available and moderately-priced meters and probes.
• Current National Institute for Occupational Safety and Health
(NIOSH) definitions of “safe” for oxygen is >19.5% (v/v) whereas
for carbon dioxide the “Permissible Exposure Level (PEL) is <5,000
ppm (on-line: 2008).
WINERY SANITATION
• Once cleared for entry, employee(s) must be equipped with harnesses
and tethered to the outside through side/bottom manhole where at least
one worker remains on-station during the entire operation.
• To prevent compromising the integrity of the protective oxide coating
on stainless steel, only soft–bristle brushes should be used in cases
where scrubbing is required.
• Once stainless steel surfaces are scratched, these rapidly become
susceptible to oxidation and corrosion.
• As such, fiber or metal “scratch” pads or brushes should never be used
for removal of tenacious deposits.
Water Chemistry: Basic components of the sanitation program includes
water quality (hardness, odor, particulates) and availability.
• Hardness: calcium, magnesium, and other alkali metals interfere with
the effectiveness of detergents, particularly bicarbonates, and
contributes to the formation of precipitates or “scale” on equipment.
WINERY SANITATION
• Besides diminishing the appearance of equipment or surface, these
precipitates serve as sites for accumulation of organic debris and
microorganisms, making subsequent sanitation efforts difficult.
• Perhaps, the least expensive method to alleviate this problem is
through installation of a water softener.
• Water should be analyzed two to four times a year depending on the
source (well or city).
• Routine testing includes pH, alkalinity, calcium hardness, iron,
silica, total dissolved solids, and a standard plate count for
microorganisms.
II. DETERGENT(S) AND DETERGENT FORMULATIONS:
• Once visible debris and film has been removed, detergents/cleaners
are incorporated into the process to solubilize any remaining deposits.
Each detergent has unique properties of action for the most effective
application.
• Dry chemicals should always be added to cold water rather than
to hot.
WINERY SANITATION
• Generally, increasing the concentration beyond recommended levels
provides little additional benefit and is not cost effective.
• Typical components of a detergent formulation:
• alkali (“active ingredient”)
• sequestering agent(s)
• surfactants
• Strong alkali's or `caustics,' such as NaOH (caustic soda or lye) or
KOH (caustic potash) are most commonly used at this stage.
• Although concentrations and temperatures vary, a typical protocol
calls for 1-2% (w/v) caustic dissolved in warm (approx 38oC/100oF)
water followed by heating the solution to 75oC/167oF to 80oC/176oF
and application to contact surface for 15-20 minutes.
• Both caustics have >detergent properties and >antimicrobial activity
(viable cells as well as spores and bacteriophage) as well.
• May also serve as sterilizing agents as well.
• However, strong alkalis are corrosive towards mild steel and, in
excess, stainless steel as well.
WINERY SANITATION
• Silicates: Although less caustic than NaOH, sodium ortho– and
meta–silicates (Na2SiO3) silicates possess better detergent
properties, and are less corrosive towards equipment than caustics.
• In the case of low organic load situations, mild alkalies such as
sodium carbonate (soda ash) or trisodium phosphate (TSP) find
application.
• However, regular use of sodium carbonate may contribute to
precipitate (“scale”) formation when used in hard water.
• TSP may be corrosive upon repeated applications on mild steel
and is degraded by hot water. Regular use leads to elevated
phosphate level in discharge water may contribute to algal
blooms (Butzke, 2010).
• In many wineries, the caustic wash cycle followed by a thorough
citric acid-water rinse, fulfills the sanitation requirements for
fermentors and wine storage tanks.
• Chelating or Sequestering Agents:
• Can also be added to detergent formulation at extra cost for
removal of Ca++ and Mg+ (components of precipitates).
WINERY SANITATION
• Trisodium phosphate (TSP) at 4 g/L, or polyphosphates (sodium
hexametaphosphate or CalgonTM and/or sodium tetraphosphate QuadrofosTM).
• EDTA - more expensive, less degradation.
• Phosphoric acid (0.5% v/v). Dissolves scale and is relatively noncorrosive and compatible with nonionic wetting agents.
Wetting Agents (Surfactants):
• Non-corrosive compounds that “break-down” organic deposits by
interspersing water.
• Typically, 13-15 carbon chains - hydrophobic end with affinity for oils
and a carboxyl group (COO-) hydrophilic end with affinity for water.
• Align themselves at the interface between water and organic layers.
• Very soluble in cold water and not impacted by hot water.
• Detergent formulations typically have around 0.15% wetting agents
• Many are stable in both acid and alkaline solutions.
WINERY SANITATION
•
Several of the noted components may be present pre-mixed and readyfor-use in a single detergent formulation.
• Referred to as “built detergents” or “built cleaners”
• Depending upon composition, may achieve multiple cleaning goals in
a single application.
• Alternatively, formulations can be prepared at the winery using
individual chemicals and ingredients.
• When formulating detergent mixes, the staff should consult
specific suppliers for information related to proper use of
chemicals.
III. SANITIZERS
• Depending upon stage in processing and the need for biological
stability, it may be necessary to follow-up using of one, or more,
sanitizing/sterilizing agents.
• Regardless of application, sanitizing agents should be used once the
surface has been thoroughly cleaned.
WINERY SANITATION
•
Selection of sanitizing agents includes:
• Halogens (iodine and, historically, chorine-based compounds)
• Quaternary ammonium salts,
• Peroxides,
• Hot water/steam,
• Ozone.
• Depending upon application (eg., winery hose), acidulated sulfur
dioxide is also widely used.
Halogens (Chlorine and Iodine):
• Chlorine and chlorine-based sanitizers: HISTORICAL
PERSPECTIVE!!
• Use of chlorine or chlorine-containing detergents/sanitizing agents
may increase the potential for formation of environmental TCA.
• NOT RECOMMENDED FOR ANY USE IN THE WINERY
ENVIRONMENT.
• We do not allow our janitorial staff to use chlorine or chlorinecontaining product.
WINERY SANITATION
• Iodine-Based Sanitizers: formulations of iodine + nonionic wetting
agents are called iodophors.
• Iodophores are not rapidly degraded by organics and relatively
nonirritating.
• Maximum effectiveness at pH 4-5 (concentration of I2 is maximum)
• Includes phosphoric acid to ensure low pH.
• Concerns with the use of iodine-based sanitizers:
• Volatilize at >120oF
• may stain PVC and hose.
• foams excessively.
Quaternary Ammonium Compounds (QUATS):
• Exist as cationic surface-active agents (surfactants), of the general
structure NR4+ :
• Nitrogen is covalently bonded to four alkyl or aromatic groups.
WINERY SANITATION
• Unlike other ionic species, QUATS are permanently charged and,
thus, independent of the pH of solution.
• The antimicrobial properties of QUATS reside in their strong affinity
for negatively-charged surfaces, such as bacterial cell surfaces,
where they function by disrupting cell membrane operation.
• In addition to activity and stability over a broad pH range, activity is
not compromised by hard water.
• QUATS are often employed for the control of mold on the outside
surfaces of tanks as well as winery walls, floors and in drains. Here,
the formulation is sprayed onto the surface and left without rinsing.
• Most lab bench-top sterilants are QUATS.
Other Agents:
Acidulated Sulfur Dioxide:
• Acidulated SO2 may be used as an effective sanitizing agent
especially for hoses and other equipment.
• Because the antimicrobial activity of SO2 is pH dependent, the
agent (100 mg/L SO2 or 200 mg/L potassium metabisulfite) is
usually made up in acidulated solution by inclusion of 3-5 g/L citric
acid.
WINERY SANITATION
• Caution: Strong SO2 solutions irreversibly damage silicon, rubber and
plastic parts such as bungs and press membranes/bladders (Butzke,
2010). Continual exposure may lead to corrosion of 304-grade
stainless steel surfaces.
• Due to volatility and corrosive properties, SO2 solutions should only
be used in a well ventilated area away from metal surfaces due to
volatility and corrosive properties.
• Employees should be cautioned to avoid direct contact or inhalation of
SO2.
• Although wineries commonly prepare this sanitizer in acidulated, hot
water (60°C/140°F), this practice serves to increase the volatility as
well as increased safety risks. When not in use, SO2 solutions should
be sealed to minimize volatilization.
Peroxides: Also known as “proxy” compounds, the group consists of
strong oxidizing agents including hydrogen peroxide and peroxyacetic acidic having at least one pair of highly reactive covalently
bonded oxygen atoms (–O–O–).
WINERY SANITATION
Hydrogen peroxide (H2O2): highly reactive oxidant that breaks down to
generate toxic singlet or superoxide (O2–) oxygen.
• Commercially available in concentrations ranging from 3-30% v/v.
• The former can be purchased at pharmacies as a topical
antiseptic for treatment of abrasions and is used in the lab for
microbiological testing.
• The more highly concentrated form, must be obtained from
chemical supply companies.
• At concentrations >5% v/v, hydrogen peroxide becomes a strong
irritant that can cause burns and blisters on exposed skin. Staff
working with the agent should be trained and cautioned in its use.
• Unless stored in a sealed container, H2O2 rapidly breaks down with
time.
Sodium percarbonate (2 Na2CO3•3 H2O2) : stabilized powder containing
hydrogen peroxide.
• Widely used as the active component in laundry detergent and all
fabric bleach as well as denture cleaners, pulp and paper bleaching
and wine barrel treatment.
•
•
WINERY SANITATION
The highly reactive product has an available [O2] equivalent to 27.5%
H2O2 and, like peroxide, breaks down to the reactive form, oxygen as
well as water and sodium carbonate upon full reaction.
Sodium percarbonate is sold under the trade name Proxycarb™ and
is widely used to treat barrels believed to be contaminated with
spoilage microorganisms and/or to neutralize offensive odors that
may be present.
• 100% kill is unlikely given the porous nature of wood.
Peroxyacetic acid (PAA): sometimes referred to as “peracetic acid,” is
also a highly reactive oxidant with antimicrobial properties similar to
hydrogen peroxide.
• All commercial PAA products contain an equilibrium of PAA,
hydrogen peroxide, acetic acid, and water.
• As a sanitizer and sterilant, PAA has several desirable characteristics
not found with H2O2 including:
• Better stability at application concentrations (100 to 200 mg/L),
• Improved compatibility with hard water, and reduced foaming.
WINERY SANITATION
• PAA exhibits reduced corrosive properties and is biodegradable.
• Like hydrogen peroxide, concentrated PAA (40% w/v) is a highly toxic
oxidant.
• In diluted form, its best applications include barrel and bottling line
sanitation and sterilization.
Physical Sterilants:
Hot water (>82oC/180oF) and steam
• Historically, considered as the “ideal” sterilant.
• In addition to their universally lethal impact on microbes, hot
water/steam are noncorrosive and, properly used, leave no
residue.
• Major concerns with the use of either/both include costs associated
with generation and delivery of sufficient volumes to meet the time
and temperature requirements for sterilization.
• Further, regular use of either/both may degrade gaskets more
rapidly than other agents.
WINERY SANITATION
•
•
•
The most frequent application for hot water/steam is bottling line
sterilization. Hot water sterilization requires temperatures greater than
82oC/180oF for no less than 20 minutes as monitored at the point most
distal to the steam source (i.e., the end of the line, fill spouts, etc.).
The sterilization cycle begins when the target temperature is reached.
Where “hard” water is used, salt precipitates (scale) may be a concern
during rinse and cool-down cycle.
Ozone: Ozone (O3) is one of the most potent sanitizers available and,
thus, is finding increased use as a replacement for other sanitizers in
the food and wine industry.
• As an oxidant, ozone’s properties reside in its inherent instability and
rapid release of oxygen in transition from O3 to O2 upon contact with
soluble or particulate oxidizable substrates.
• In that decomposition is accelerated by heat, the gas is typically used
in conjunction with cold water applications.
• Decomposition a function of organic load + temperature.
WINERY SANITATION
• Whereas early uses of ozone centered on cold water CIP systems
such as bottling lines and heat exchangers etc., many wineries are
now using it for domestic and wastewater treatment as well as in
barrel washing.
• Because O3 rapidly degrades to O2, it cannot be stored and must be
generated on demand.
• Long-term effect on equipment (particularly soft parts such as
gaskets) is unclear.
• Very low solubility ->out gassing (health and safety issue).
• Ozone is a strong irritant and uncontrolled exposure may result in
inflammation of eyes, nose throat and lungs.
• The legal maximum concentration for an 8–hour continuous exposure
is 0.1 mg/L whereas the limit for short–term exposure is 0.2 mg/L for
10 minutes (Khadre et al., 2001).
• Staff should be well trained and use proper ozone safety monitors.
WINERY SANITATION
Ultraviolet light (UVL)/Photon sterilization technology (PST):
• Although UVL is directly effective against microbes, it has very low
penetrative capabilities and even a thin film of water will serve as an
effective barrier between radiation and microbes.
• Photon sterilization technology (PST) systems work by generating
photons from UV rays created by a series of fluorescent tubes.
• Effective against both airborne microbes and those present on
contact surfaces.
• Although relatively new to the wine industry, such systems have been
used in the food industry for sometime.
Dry Ice Blasting. The Rajeunir (Fr. "rejuvenate") system uses dry ice to
effect removal of surface contaminants (tartrates, etc) in barrels without
significant (1.25 mm) abrasion .
Ultrasound/HPU: Electrical energy can be converted to lethal ultrasonic
sound waves.
• HPU generates a stream of “micro-bubbles” that, upon cavitation,
generate high energy shock waves that impact/disrupt particulates on
surfaces.
WINERY SANITATION
• HPU is used for both cleaning and sanitizing, especially, barrels.
• Advantages of HPU systems include reduced energy costs as well as
reduced chemical input and low volume water usage.
Biofilms: While cleaning and sanitation processes will significantly lower
microbial populations, there may be survivors depending on the degree
of debris buildup and the effort expended during routine sanitation
operations.
• Growth of survivors may form a colony of cells known as a “biofilm.”
• Biofilms exhibit increased resistance to antimicrobials and are
difficult to remove.
• Eventually, these colonies become large enough to trap soil, debris,
nutrients, and other microorganisms
• Biofilm formation by O. oeni as well as Brettanomyces bruxellensis
has been observed on stainless steel.
• A commonly used procedure for removing biofilms in clean–in–
place systems utilizes a caustic wash (167°F for 30 minutes)
followed by acid (167°F for 30 minutes).
WINERY SANITATION
IV. FINISHING OPERATIONS:
• Once the cleaning/sanitation cycle is completed, contact surfaces
should be thoroughly rinsed, using either hot or cold water, to
remove residual chemicals.
• Citric acid is often incorporated into the rinse to neutralize alkaline
detergent residues.
V. SANITATION MONITORING:
• Effectiveness of the sanitation program is, necessarily, an ongoing
concern.
• Efforts to detect poorly cleaned and sanitized surfaces may range
from simple subjective sensory evaluation (i.e., absence of odor and
stains) to the use of surface swabs and enzymatic assays.
• Sampling sites should be selected to include all points that may
escape treatment and, thus, harbor microorganisms.
• Important among these are contact surfaces of processing equipment
as well as the interior of pipelines, conveyors and tanks.
WINERY SANITATION
• Other areas subject to indirect contamination should also be
reviewed:
• These include condensate from ceilings or equipment, aerosols,
and lubricants.
• Testing protocol include conventional direct contact testing utilizing
swab tests (4” x 4” area) and agar (Rodac) plates as well as
bioluminescence methods using luciferin-luciferase (“fire-fly”)
enzyme.
• Enzymatic methods monitor environmental ATP and assumes a
direct relationship to living cells.
• Interferences and problems with method include the assumption
that ATP formation during growth of yeast and bacteria is
equivalent. In fact, yeast may produce >100x the amount of ATP
produced by bacteria at same stage of growth.
WINERY SANITATION
SAFETY ISSUES (SUMMARY):
Sanitation typically uses strong agents such as oxidants (peroxides,
ozone), caustics (NaOH or KOH), and/or acidic chemicals (phosphoric
acid) as well as pressurized hot water and/or steam.
• Further, slippery floors resulting from discharge of detergents
represent ongoing safety concerns .
• Employees regularly in contact with sanitizing chemicals should
thoroughly trained (and retrained as necessary) in their safe use.
The employee’s “right to know” is a cornerstone of Federal and State
health and safety regulations.
• Thus, part of any employee training program should include
identification of the health and safety information concerns associated
with any chemical or operation.
• This information is contained in the Material Safety Data Sheets
(MSDS) that accompany shipments of chemicals and online.
• Must be made available to any employee at any time (24/7) of during
the workday.
WINERY SANITATION
• To comply with regulations, it is recommended that they be kept
alphabetized in clearly identifiable and displayed binders in the
work area.
Further, workers should be issued (or required to purchase) personal
protective equipment (PPE) including water–repellant aprons and boots
(non-skid soles) in addition to goggles and appropriate gloves.
Fementors and/or storage tanks are considered as “confined spaces.”
• When it is necessary for workers to enter, special health and safety
regulations apply.
• These include preliminary forced-air ventilation of the tank to
reduce carbon dioxide levels followed by verification that have safe
levels have been reached.
• Current National Institute for Occupational Safety and Health
(NIOSH) definitions of “safe” for oxygen is >19.5% (v/v) whereas
for carbon dioxide the permissible exposure level (PEL) is <5,000
ppm (on-line: 2008). Carbon dioxide and oxygen are easily
measured by use of readily available and moderately-priced meters
WINERY SANITATION
• Once cleared for entry, employee(s) must be equipped with
harnesses and tethered to the outside through side/bottom
manhole where at least one worker remains on-station during the
entire operation.
Because of safety concerns, tank placards must include a confined
space warning such as that seen in the following figure:
Required
OSHA
Warning
Required TTB
documentation
WINERY SANITATION
TRAINING AND DOCUMENTATION
• While winery sanitation programs may vary in terms of both schedules
and protocol, it is important to insure that such operations are
carried out in a safe and consistent manner.
• One way to accomplish this goal is to develop a system of documents
that not only defines each step in the process but validates the results
as well.
• Such operational guides are referred to as Standard Operating
Procedures (SOPs) which describe in a concise manner, the sitespecific procedure from set-up to clean-up.
• In the case of winery sanitation, the SOP defines not only the
chemicals, and the concentrations used, but the equipment
required and time-frame as well as any follow-up testing required.
• Employee training is required by law. This applies not only to the first
time a new employee carries out the operation but any supplemental
(“tailgates”) or retraining that may be necessary.
• The supervisor should always document attendance at such
training sessions and rosters should be kept on file for inspection
as necessary.
QUESTIONS?
CONTACT INFORMATION:
K.C. Fugelsang,
Department of Viticulture and Enology,
C.S.U. Fresno
559.278.2791
[email protected]