The increase in antibiotic-resistant bacteria has researchers looking for new natural compounds to use for food preservation and control of disease-causing bacteria. The leaves of the carob tree appear to be a promising weapon, according to new research.
The carob tree grows in the Mediterranean region and is a member of the legume family. Its pods contain seeds that are used as a chocolate substitute but without the stimulants caffeine and theobromine that are naturally found in chocolate.
The extract of carob leaves contain antibacterial substances that inhibit the growth of Listeria monocytogenes.
Nadhem Aissani and colleagues from the Department of Life and Environment Sciences at the University of Cagliari in Italy tested the ability of extracts from carob leaves to inhibit the growth of a range of microorganisms in laboratory cultures. Leaves of the tree were collected, dried in the dark at room temperature, sealed in paper bags at room temperature, and kept in the dark until they were used. Through a series of tests, the researchers determined that the extract of carob leaves contain antibacterial substances that inhibit the growth of Listeria monocytogenes.
The Centers for Disease Control and Prevention (CDC) has received reports of 20 people infected with the bacteria from 12 states and the District of Columbia as of October 11, 2012. At least four deaths have been reported, including one fetal loss. All of the cases have been linked to imported Frescolina Marte brand ricotta salata cheese. Even though the cheese has been recalled, it may still be in people’s homes. The CDC warns against eating the cheese.
The report, published online on in the American Chemical Society’s Journal of Agricultural and Food Chemistry, describes the tests and offers a possible explanation for the antibacterial action of carob extracts. Further studies are planned to test carob extracts on Listeria growing in meat and fish.