Toxigenic Staphylococcus aureus contamination in ready-to-eat (RTE) food is a leading cause of foodborne illness in Korea. To monitor food contamination by S. aureus, a total of 3332 RTE food samples were selected from nationwide wholesale marts between 2003 and 2004 and examined. A total of 285 (8.6%) of the overall samples were contaminated by S. aureus. According to the analysis, 31.6% of the tested cream-cakes, 19.8% of the raw fish, and 19.3% of the rice cakes with filling were contaminated with S. aureus. Forty-seven percent of the strains isolated from the contaminated food were enterotoxigenic S. aureus. The phenotypic result of the strain isolated from food showed that 48% of the strains produced one or more toxins, such as staphylococcal enterotoxins A, B, and C (SEA, SEB, and SEC). At least one SEA was produced by over 90% of the toxigenic strains. Other toxins, such as SEB, SEC, SED, SEA+SEC, and SEC+SED, were each detected. Toxic shock syndrome toxin 1 (TSST-1), a causative agent of toxic shock syndrome, was detected in 13 strains of the toxigenic isolates from the food. As the result of genotyping, 22 strains with a toxin gene that was not detected in the phenotypic analysis were also detected. Sixty-nine percent of the toxigenic strains had at least one sea gene, and the most prevalent genotype was sea+seh (34.4%), followed by sea (18.8%) and sea+seg+sei (15.6%). The tst gene encoding TSST-1 was found in 13 strains (13.5%). The genes (eta and etb) encoding exfoliative toxins A and B were not detected in any of the samples.

We evaluated organosulphur compounds in Allium vegetables, including garlic, elephant garlic and onion, using high-performance liquid chromatography. Among organosulphur compounds, elephant garlic had considerable γ-glutamyl peptides, and garlic had the highest alliin content. Onion had low level of organosulphur compounds than did elephant garlic and garlic. In addition, antioxidant capacities were evaluated by oxygen radical absorbance capacity (ORAC) values and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay. The results showed that garlic had the highest antioxidant capacity, followed by elephant garlic and onion. Furthermore, a positive correlation was observed between antioxidant activities and organosulphur compounds (R > 0.77). Therefore, our results indicate that there was a close relationship between antioxidant capacity and organosulphur compounds in Allium vegetables.

AbstractsThis study was performed to the development of methods for the identification and detection of corn oil in adulterated sesame oil. The fatty acids composition and carbon isotope ratio of authentic sesame oil and adulterated sesame oil with corn oil were studied by using GC‐FID and IRMS. The content of palmitic (P), linoleic (L), and linolenic (Ln) acids increased gradually as the mixed rate of corn oil was increased, whereas the content of stearic (S) and oleic (O) acids decreased. On increasing the mixing ratio of corn oil, the stearic acid contents and the (L × L)/O ratio showed significant differences between authentic and adulterated sesame oils (p < 0.05). The δ13C‰ value for authentic sesame oil and corn oil fell into the range of −27.68 to −29.26‰ and −16.51 to −17.27‰. The adulterant had more carbon‐13 compared with those of authentic sesame oil and the δ13C‰ value was increased linearly (r2 = 0.996). Therefore, the combination of the stearic acid% (<4.8%), (L × L)/O ratio (>56.1) and the carbon isotope ratio (> −27.0‰) turned out to be a good tool for detecting the adulteration of sesame oil with the cheaper corn oil, up to the 10% level.

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