Safe Methods to Store, Preserve, and Enjoy
Food Safety/Microbiology Specialist, Department of Food Science and Technology
WHAT IS GARLIC?
G a r l i c ( A l l i u m s a t i v u m
) i s a m e m b e r o f t h e
S e l e c t g a r l i c h e a d s t h a t a r e f i r m a n d t i g h t -
Amaryllis family (Amaryllidaceae), which also
i n c l u d e s l e e k s , o n i o n s , a n d s h a l l o t s . I t i s a
perennial with an underground bulb (head)composed of pungent bulblets commonly called
If you grow your own garlic, it is important to let
it mature after harvest. Spread the harvested gar-
Approximately 90 percent of the garlic grown
lic heads or bulbs on newspapers or wire racks
in the United States is grown in California.
out of direct sunlight in a well-ventilated place to
California Early and California Late are the two
cure for 2 to 3 weeks or until skins are papery.
major commercial varieties. California Early has
white skins and is planted in November for har-vest in June. California Late has light purple
Commercially, garlic is stored near 32°F (0°C).
skins and is planted in December for harvest in
However, most home refrigerators are too warm
July and August. The largest garlic variety,
for ideal long-term storage of garlic. Instead,
Elephant Garlic, has a very mild-flavored clove
store it in a cool, dry, well-ventilated place in
and is a close relative of the leek.
well-ventilated containers such as mesh bags.
The pungent flavor of garlic is caused by a
S t o r a g e l i f e i s 3 t o 5 m o n t h s u n d e r c o o l
chemical reaction that occurs when the garlic
(60°F/16°C), dry, dark conditions.
cells are broken. The flavor is most intense
PEELING GARLIC CLOVES
shortly after cutting or chopping. This chemicalreaction cannot occur after garlic is cooked,
Peeling whole cloves requires that the papery
which is why roasted garlic is sweet rather than
skin be removed without cutting into the clove. If
the garlic is going to be chopped or sliced, the
skin can be removed by pressing the clove withthe flat side of a knife until the clove and skin
Regardless of its flavor potency, garlic is a low-
crack. The skin can then be easily removed.
acid vegetable. The pH of a clove of garlic typi-
cally ranges from 5.3 to 6.3. As with all low-acidvegetables, garlic will support the growth and
Roasted garlic, which has become popular in
subsequent toxin production of the bacterium
recent years, is sweet to the taste and is delicious
when given the right con-
on bread or crackers as an appetizer or served as
These conditions include improper
a vegetable side dish. To prepare roasted garlic,
home canning and improper preparation and
leave the head whole and cut off the tip of the
storage of fresh herb and garlic-in-oil mixtures.
head, exposing the cloves. Allow one-half to one
Moisture, room temperature, lack of oxygen,
head per person. Put the head (or heads) in a
and low-acid conditions all favor the growth of
baking dish or wrap them in aluminum foil,
When growing, this bac-
sprinkle with olive oil or pat with butter, and
terium produces an extremely potent toxin that
season with a little salt and pepper and some
causes the illness botulism. If untreated, death
fresh or dried thyme if desired. Bake at 350°F
can result within a few days of consuming the
(176°C) until very soft and tender (about 45 min-
toxic food. It is important to follow the direc-
utes to 1 hour). The roasted garlic cloves can be
tions in this publication carefully to make sure
easily squeezed from their skins and spread with
2 • Garlic: Safe Methods to Store, Preserve, and Enjoy
the wine or vinegar. The garlic-flavored liquidand the garlic cloves may be used to flavor dish-
Garlic can be frozen in a number of ways.
es. Do not store the garlic/liquid mixture at room
1. Chop the garlic, wrap it tightly in a plastic
temperature because it will rapidly develop mold
freezer bag or in plastic wrap, and freeze. To use,
grate or break off the amount needed.
STORING GARLIC IN OIL
Extreme care must be taken when preparing fla-
3. Peel the cloves and puree them with oil in a
vored oils with garlic or when storing garlic in
blender or food processor using 2 parts oil to 1
oil. Peeled garlic cloves may be submerged in oil
part garlic. The puree will stay soft enough in the
and stored in the freezer for several months. Do
freezer to scrape out parts to use in sautéing.
not store garlic in oil at room temperature.
Freeze this mixture immediately—do not store it
Garlic-in-oil mixtures stored at room temperature
at room temperature.
The combination of the
provide perfect conditions for producing botu-
low-acid garlic, the exclusion of air (by mixing
lism toxin (low acidity, no free oxygen in the oil,
with oil), and room-temperature storage can sup-
and warm temperatures). The same hazard exists
port the growth of Clostridium botulinum
for roasted garlic stored in oil. At least three out-
breaks of botulism associated with garlic-in-oilmixtures have been reported in North America.
Dry only fresh, firm garlic cloves with no bruises.
By law, commercially prepared garlic in oil
To prepare, separate and peel the cloves. Cut in
has been prepared using strict guidelines and
half lengthwise. No additional predrying treat-
must contain citric or phosphoric acid to increase
ment is necessary. Dry at 140˚F (60˚C) for 2
the acidity. Unfortunately, there is no easy or
hours, then reduce heat to 130˚F (54˚C) until com-
reliable method to acidify garlic in the home.
Acidifying garlic in vinegar is a lengthy and
If desired, garlic salt may be made from dried
highly variable process; a whole clove of garlic
garlic. Powder dried garlic by processing in a
covered with vinegar can take from 3 days to
blender or food processor until fine. Add 4 parts
more than 1 week to sufficiently acidify. As an
salt to 1 part garlic powder and blend 1 to 2 sec-
alternative, properly prepared dried garlic cloves
onds. If blended longer, the salt will become too
Why did my garlic turn blue?
Canning of garlic is not recommended. Garlic is a
Garlic contains anthocyanins, water-sol-
low-acid vegetable that requires a pressure can-
uble pigments that can turn blue or purple under
ner to be properly processed. Garlic loses most of
acidic conditions. This is a variable phenomenon
its flavor when heated in this way. For this rea-
that is more pronounced for immature garlic but
son, adequate processing times have not been
can differ among cloves within a single head of
garlic. If you grow your own garlic, be sure tomature it at room temperature for a couple of
STORING GARLIC IN WINE OR VINEGAR
Peeled cloves may be submerged in wine or vine-gar and stored in the refrigerator. A dry white or
: Research on food preservation is ongo-
red wine is suggested; white or wine vinegars
ing—recommendations may change. Make sure
also work well. The garlic/liquid mixture should
your food preservation information is always
keep for about 4 months in the refrigerator.
current. Always follow up-to-date, tested guide-
Discard both the cloves and the liquid if there are
lines and recipes from reliable sources.
signs of mold or yeast growth on the surface of
Special thanks to Lora Tanumihardja for her assistance in collecting materials. The Department of Food Science Home Page can be
found at http://www-foodsci.ucdavis.edu/. Portions of this publication were adapted from Food Safety Advisor 1995 Volunteer
by Virginia Hiller (Pullman: Washington State University, 1995). The University of California, in accordance with
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Sarcoïdose en de Mexicaanse griep L.S.J. Kamphuis, dr. P. van Biezen, Prof.Dr. A.D.M.E. Osterhaus, dr. A.A. van der Eijk, dr. J.A.M. van Laar, dr. P.L.A. van Daele en dr. P.M. van Hagen, Erasmus Universitair Medisch Centrum RotterdamU heeft ongetwijfeld gehoord over de Mexicaanse griep, ook wel Nieuwe Influenza A (H1N1) genoemd. Wereldwijd zijn er inmiddels honderdduizenden bevestigde besme
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