M: Food Microbiology & Safety JFS M: Food Microbiology and Safety Evaluation of the Ability of Eleutherine americana Crude Extract as Natural Food Additive in Cooked Pork B.O.T. IFESAN, S. SIRIPONGVUTIKORN, N. HUTADILOK-TOWATANA, AND S.P. VORAVUTHIKUNCHAI ABSTRACT: The scavenging activities of crude ethanolic extract from Eleutherine americana, on 2,2-diphenyl-1- picrylhydrazyl (DPPH) and hydroxyl free radicals were investigated. The results revealed that the extract produced IC 50 values of 8.4 μg/mL and 0.78 mg/mL on DPPH and hydroxyl free radicals, respectively. The total phenolic con- tent of the extract was determined using the Folin–Ciocalteu reagent and the crude extract yielded high phenolic content of 4.56 μmol gallic acid equivalent per milligram dried extract. The extract, at different concentrations, was incorporated into pork, cooked in the microwave, and stored at 4 ◦ C for 9 d. The crude extract demonstrated an- tioxidant activity, which increases with increased extract concentrations and retarded lipid oxidation in the cooked pork. Antibacterial activity of the extract against Staphylococcus aureus in the cooked pork revealed that at a con- centration of 10.8 mg/100 g, the extract reduced the bacterial population by 0.57 log compared to control at 9 d of storage. The sensory results revealed that the pork samples treated with the extract and the control sample were not significantly different from day 0 to 6; however, on day 9 the treatments were significantly scored higher than the control. Furthermore, addition of the extract led to an increase in the redness values of the pork and this was acceptable from the sensory point of view. E. americana crude extract could be a promising novel antioxidant to prevent lipid oxidation and a potential natural color enhancer of red meat and meat products. Keywords: antibacterial activity, Eleutherine americana, free radical scavenging, lipid oxidation, sensory attributes Introduction T he growing interest in convenience foods is making ready- to-eat meat products to become more desirable and well known. Lipid oxidation is a process by which quality loss of muscle foods occur causing chemical spoilage in food systems. Precooked meat especially pork is susceptible to lipid oxidation compared to those of beef and sheep (Kanner 1994; Chanon and Trout 2002; Jayathilakan and others 2007) because of its relatively high content of unsaturated fatty acids (Enser and others 1996). In addition, the warmed over flavor develops in a few hours when the cooked meat is stored at 4 ◦ C (Tims and Watts 1958), together with microbial con- tamination (Delaquis and others 1999). A variety of microorganisms may cause food spoilage and poi- soning which are major concerns of the food industry. Staphylo- coccus aureus is one of the most important foodborne pathogens found in ready-to-eat food products. Several studies were reported where S. aureus was isolated from a range of food materials (Aycicek and others 2005; Normanno and others 2005, 2007; Ifesan and oth- ers 2009a), while both animal and human have been suggested as sources of contamination. Dewaal and Bhuiya (2007) reported that the most common hazard bacteria in pork was S. aureus. The use of chemicals to enhance food safety is of great inter- est to the food industry. However, consumers have grown concerns MS 20080926 Submitted 11/19/2008, Accepted 5/27/2009. Authors Ife- san and Voravuthikunchai are with Dept. of Microbiology. Author Siripongvutikorn is with Dept. of Food Technology, Faculty of Agro- Industry. Author Hutadilok-Towatana is with Dept. of Biochemistry and authors Hutadilok-Towatana and Voravuthikunchai are also with Natu- ral Products Research Centre, Faculty of Science, Prince of Songkla Univ., Songkhla, 90112, Thailand. Direct inquiries to author Voravuthikunchai (E-mail: supayang.v@psu.ac.th). about the health risks associated with the use of synthetic chemi- cals. It has been demonstrated that butylated hyroxytoluene (BHT) may cause internal and external hemorrhaging at high dose, which could cause death in some strains of mice and guinea pigs (Shahidi and Wanasundara 1992). The use of natural preservatives to im- prove the shelf life of meat products is a promising technology as many herbs, spices and their essential oils have demonstrated an- tioxidant (Rey and others 2005; Banon and others 2007; Carpen- ter and others 2007; Jayathilakan and others 2007; Juntachote and others 2007) and antimicrobial properties (Ahn and others 2007; Solomakos and others 2008; Gutierrez and others 2008). However, the efficacy of many natural additives may be reduced by certain food components (Glass and Johnson 2004), which include high levels of fat or protein (Aureli and others 1992) and presence of car- bohydrates in foods (Shelef and others 1984). Eleutherine americana Merr. is an herbal plant whose red bulb has been commonly employed in Asian cuisine. E. americana orig- inates from tropical America where its elongated red tubers have been used by the local inhabitants to treat numerous diseases. It has been cultivated in Javanese gardens and now can be found worldwide particularly in South Africa, and rubber plantations in Java. The plant, belonging to the Iridaceae family, is now widely cultivated in China for ornamental and medicinal purposes. Active compounds from E. americana has been reported to display impor- tant biological activities. Eleutherol, eleutherin, and isoeleutherin showed both antifungal activity and enhancement of the blood cur- rent of the coronary artery (Zhengxiong and others 1984). In our preliminary studies, we reported the inhibitory activity of this plant extract against S. aureus isolated from foods (Ifesan and others 2009a), and the antistaphylococcal activity of the par- tially purified fractions and pure compounds against methicillin M352 JOURNAL OF FOOD SCIENCE—Vol. 74, Nr. 7, 2009 C  2009 Institute of Food Technologists R  doi: 10.1111/j.1750-3841.2009.01254.x Further reproduction without permission is prohibited