Effect of capsicum extracts and cinnamic acid on the growth of some important bacteria in dairy products

Capsicum species have been the object of different studies (Dorantes et al., 2000; Careaga et al., 2003; Acero-Ortega et al., 2005) in order to determine their antimicrobial activity, the compounds that would be responsible for it, and the microorganisms that could be affected by it, finding that Staphylococcus aureus, Salmonella tiphymurium, Listeria monocytogenes, Pseudomonas aureaginosa and Bacillus cereus are susceptible to inhibition by Capsicum extracts. Some of the active compounds responsible for the inhibitory action are t-cinnamic acid and its derivatives, which are intermediate compounds in phenylpropanoids pathway. Capsicum annuum oleoresins are “generally recognized as safe” (GRAS) by the FDA, and so their use as natural antimicrobials is safe. However, it is important to know through predictive microbiology and modeling the quantitative effect of the Capsicum extracts, the active compounds, and the interactions with other factors such as pH and temperature. One of the food products that has been involved in outbreaks is fresh rennetcurdled cheese, which has a rich nutrient content, a high water activity and low acidity, which make it an adequate culture medium for the growth of a wide variety of bacteria. Some of these bacteria are known to cause food-borne illness, such as Staphylococcus aureus. It has been estimated that consumption of foods contaminated by this microorganism is responsible for 185,060 illnesses, 1,753 hospitalizations and two deaths per year in the United States. In the United Kingdom since 1980, numbers of reported cases have not exceeded 189 per year, although this is only a small percentage of actual cases (Sutherland and Varnam, 2002). S. aureus has also been involved in food-borne diseases in México, especially in the consumption of milk products. Staphylococcal enterointoxication (staphylococcal food poisoning) results from the ingestion of enterotoxins that are synthesized during growth of S. aureus in foods. S. aureus is capable of producing an enterotoxin in conditions such as: water activity >0.85, a range of pH between 4 to 9.8, temperatures from 10 to 48 °C and a good nutrient supply such as that provided by fresh cheese and other milk products (Halpin-Dohnalek and Marth, 1989).