• Korean Journal of Veterinary Service
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• v.19 no.1
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• pp.39-45
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• 1996

Sulfonamides are widely used to treat mastitis of cattle in field. The study was carried out to analyze sulfonamid residues In raw milk from south Kyeonggi area. The milk sample was deproteinated with acetone and defatted with hexane. The residual sulfonamides were extracted with ethylacetate, concentrated under vaccum, reconstituted with the acetate buffer-methanol mixture, reacted with fluorescamine, and then analyzed by HPLC-fluorescence detector(EX. 39nm, Em. 495nm) with methanol : acetate buffer system(3/2, v /v) as a mobile phase. The results analyzed by Thin layer chromatography and High performance liquid chromatography were summarized as follows. 1. A total of 24 cases out of 478 raw milk samples(5.0%) collected during April and May showed positive reaction to sulfonamide residues. Among 24 positive reactors, 9 cases were positive to sulfanilamides(32.1%), 8 cases were positive to sulfathiazoles(28.6%) and 5 cases were positive to sulfamonomthoxines (7.9%) , respectively. 2. During July and August, 31 cases out of 464 raw milk samples(6.7%) showed positive re action to sulfonamide residues. Among them S cases were positive to sulfanilamides, 5 cases sulfathiazoles and 5 cases sulfamonomethoxines(16.1%), respectively.

• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.421-429
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• 2011

For precise identification of a Lactobacillus K1 isolate, LC-MS/MS analysis of the putative surface layer protein was performed. The results obtained from LTQ-FT-ICR mass spectrometry confirmed that the analyzed protein spot is the surface layer protein originating from Lb. helveticus species. Moreover, the identified protein has the highest similarity with the surface layer protein from Lb. helveticus R0052. To evaluate the proteomic study, multilocus sequence analysis of selected housekeeping gene sequences was performed. Combination of 16S rRNA sequencing with partial sequences for the genes encoding the RNA polymerase alpha subunit (rpoA), phenylalanyl-tRNA synthase alpha subunit (pheS), translational elongation factor Tu (tuf), and Hsp60 chaperonins (groEL) also allowed to classify the analyzed isolate as Lb. helveticus. Further classification at the strain level was achieved by sequencing of the slp gene. This gene showed 99.8% identity with the corresponding slp gene of Lb. helveticus R0052, which is in good agreement with data obtained by nano-HPLC coupled to an LTQ-FT-ICR mass spectrometer. Finally, LC-MS/MS analysis of surface layer proteins extracted from three other Lactobacillus strains proved that the proposed method is the appropriate molecular tool for the identification of S-layer-possessing lactobacilli at the species and even strain levels.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.10
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• pp.1356-1362
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• 2012

UV-VIS spectrophotometric and high-performance liquid chromatographic (HPLC-DAD) methods were applied in order to identify and quantify the composition of polyphenols in commercial cocoa-containing products. Total polyphenolic contents of cocoa mix, choco-syrup, milk chocolate, and dark chocolate were evaluated using Folin-Ciocalteu's phenol reagent according to a UV-VIS spectrometric method. Antioxidant capacities of cocoa extracts by methanol were evaluated by 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulfonic acid) (ABTS) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The obtained results show that the polyphenolic contents and antioxidant capacities of cocoa products and chocolates depend on solid cocoa content. Among the tested cocoa products and chocolates, the most abundant phenolic compound was epicatechin.