treatment prior to arrival at a winery, they
should be flushed with nitrogen and rinsed
before filling. Uncleaned bottles should be
cleaned and sterilized before use by soaking
for 2 hours in low pH 1% SO 2 and a little
glycerol, then rinsed with water. Corks can be
gamma radiation sterilized to prevent off-
odors occurring because of mold growth.
Pomace Disposal
It is essential to dispose of the pomace as
rapidly as possible after pressing. This mate-
rial must not stand in or close to the fermen-
tation room because it rapidly acetifies, and
the fruit flies carry acetic acid bacteria from
the pomace pile to clean fermenting vats.
Pomace should be further processed or scat-
tered as a thin layer on fields, where it dries
quickly and does not become a serious
breeding ground for fruit flies.
Cleaning of Used Cooperage
Alkaline solutions (soaking with 1%
sodium carbonate) are most effective in
removing tannins from new barrels. If fur-
ther treatment is necessary, steam and sev-
eral rinsings should be applied.
Other viable cleaning compounds are
sodium ortho- and metasilicates (Na 2 SiO 3 )
that are less caustic and less corrosive than
NaOH with superior detergent properties. A
lighter organic load permits the application
of milder alkalies, such as sodium carbonate
(soda ash) or trisodium phosphate. Sodium
carbonate (Na 2 CO 3 ) is an inexpensive, fre-
quently used, cleaning compound. However,
it contributes to precipitate formation in
hard water.
Polyphosphates are frequently included in
cleaning compound formulations because of
their ability to chelate calcium and magne-
sium and to prevent precipitation. Examples
are sodium tetraphosphate (Quadrofos) and
sodium hexametaphosphate (Calgon). The
amount to be included in the formulation
depends on water hardness. Acid cleaners
are formulated in specialized detergent for-
mulations (approximately 0.5%) to reduce
mineral deposits and to soften water. Phos-
phoric acid is preferred because of its low
corrosiveness and compatibility with non-
ionic wetting agents (Zoecklein et al., 1995).
Past practices have involved washing
empty containers with water and spraying
with a hot (50ºC) 20% solution of a mixture
of 90% soda ash and 10% caustic soda or
caustic potash (KOH). Both NaOH and
KOH have excellent detergent properties and
are strongly antimicrobial against viable
cells, spores, and bacteriophage. After subse-
quent washing with hot (50ºC) water, con-
tainers should be sprayed with a chlorine
sanitizer solution containing 400 ppm of
available chlorine. A cold water rinse should
follow, with subsequent drainage and drying
using a dry-wet vacuum. If mold is present,
it should be scraped off because it cannot be
removed by washing. Further precautions
include washing with a quaternary ammo-
nium compound. Paints containing copper-
8-quinolate can also control mold growth.
Burning a sulfur wick in the tank (700 mg/hl)
or adding an equivalent amount of SO 2 from
a cylinder of gas is also effective. Before use,
the tanks should be rewashed, and the
cooperage should be inspected visually and
by smelling before being filled. A warm 5%
soda-ash concentration is too high and, if
exposed too long, the wood can deteriorate.
The outside surface of wooden containers
should be washed with a dilute solution once
a year. Propylene glycol can be applied to
discourage mold growth on the surface of
the tanks. Stainless steel tanks should be
cleaned with a 400-ppm or less concentrated
solution to prevent mold growth.Removal of Tartrate Deposits
It is necessary to remove tartrate deposits
to smooth the inner surface, which becomes