Garlic as Antibiotic

Studies have shown that raw garlic has the ability to kill many bacterial germs. A group of researchers from the United Arab Emirates now report that the bulb's juice contains at least some of the constituents responsible. However, boiling that juice for 10 to 30 minutes—such as to pasteurize it—partially or completely eliminates its antibacterial effect, depending on the germ against which it's deployed.

Even boiling the juice for just 5 minutes roughly halved its germ-killing prowess, the researchers report in the March Journal of Medicinal Food.

Storing the juice—even at temperatures approaching freezing (i.e. 4 °C)—can also significantly diminish its antibiotic properties.

The authors conclude that “in order to obtain optimum [germicidal] results, garlic juice should be used fresh, and during cooking it is advisable not to expose garlic to boiling for more than 5 minutes.”

What about just using minced garlic? That’s what a Turkish research team investigated, and their findings appear in a second report in the same journal.

Ali Aydin of Istanbul University Faculty of Veterinary Medicine mixed freshly chopped garlic into ground beef and uncooked Ciğ Kőfte, a type of meatball containing bulgar wheat. Then, the researchers refrigerated some samples and left others at room temperature for up to 2 days.

Adding the garlic to ground beef slowed somewhat the growth of germs. However, it didn’t kill them or even halt their growth. For yet unexplained reasons, the garlic proved more effective in the meatballs. At 10% garlic, by weight, bacterial growth in the kőfte was 13 percent lower at room temperature than in the untreated, similarly unrefrigerated raw meatballs. The difference between refrigerated samples was even smaller.

The 10% garlic treatment was the most effective concentration tested—but so high, the researchers admit, as to risk dramatically altering a food's taste.

Their hope had been a way to reduce the risk of food poisoning in regions where refrigeration is iffy or where street vendors hold meat for long periods prior to cooking. However, the scientists concluded, minced garlic’s “antimicrobial effect, even for the highest . . . concentration, is not satisfactory from a practical point of view.”

Bottom line: Garlic is no substitute for keeping meat refrigerated until ready to cook, and your hands and work surfaces clean.