Processed Food Samples Research Articles

The Prevalence of Staphylococcus aureus and Methicillin Resistant Staphylococcus aureus in Processed Food Samples in Riyadh, Saudi Arabia

Staphylococcus aureus mainly Methicillin Resistant Staphylococcus aureus(MRSA) is a life-threatening infection that occurring in food and caused a public health concern. This study designed to examine the prevalence of S. aureus and MRSA in different types of processed food. Food samples were screened for the recovered strains of S. aureus and MRSA, and they were examined for antimicrobial susceptibility and by molecular characterization of mecA and staphylococcal cassette chromosome mec(SCCmec). Detection of virulence factors like Panton-Valentine Leukocidin (PVL), Staphylococcus aureus protein A(spa) and Staphylococcal enterotoxins(SEs) by PCR using specific primers. Among the 150 collected processed food samples, 62.7% were contaminated by S. aureus bacteria, 56.4% of which were proved as MRSA. 17% of MRSA isolates were positive for mecA genes with the SCCmec type IVb and V (11.1% each) as the solely existing types of SCCmec. None of the MRSA isolates carried mecC or mecB genes. Most of MRSA isolates were multidrug resistance and 33.3% of MRSA-mecA positive isolates also carried vancomycin resistance genes (i.e., vanB). In addition, spa gene was found among 7.5% of MRSA isolates; none of which were positive for PVL gene. Further, there were variant presence of SEs among MRSA isolates and the highest presence was from type SEH (49.1%). Generally, our results confirmed that processed foods in Saudi Arabia (Riyadh) are potential vehicles for multidrug resistant S. aureus and MRSA transmission; which are serious public health risks, and underlined the need for good hygiene practices.

Accurate Detection and Evaluation of the Gene-Editing Frequency in Plants Using Droplet Digital PCR.

Gene-editing techniques are becoming powerful tools for modifying target genes in organisms. Although several methods have been reported that detect mutations at targeted loci induced by the CRISPR/Cas system in different organisms, they are semiquantitative and have difficulty in the detection of mutants in processed food samples containing low initial concentrations of DNA and may not accurately quantify editing frequency, especially at very low frequencies in a complex polyploid plant genome. In this study, we developed a duplexed dPCR-based method for the detection and evaluation of gene-editing frequencies in plants. We described the design, performance, accurate quantification, and comparison with other detection systems. The results show that the dPCR-based method is sensitive to different kinds of gene-editing mutations induced by gene-editing. Moreover, the method is applicable to polyploid plants and processed food samples containing low initial concentrations of DNA. Compared with qPCR and NGS-based methods, the dPCR method has a lower limit of detection (LOD) of the editing frequency and a better relationship with the expected editing frequency in detecting the edited region of gene-edited rice samples. Taken together, the duplexed dPCR assay is accurate and precise, and it will be a powerful tool for the detection and evaluation of gene-editing frequencies in plants in gene-editing technology.

Dietary exposure assessment to perchlorate in the Taiwanese population: A risk assessment based on the probabilistic approach

Perchlorate is an endocrine-disrupting chemical (EDC) that contaminate various foodstuffs. Exposure to perchlorate may cause severe health problems, mainly thyroid dysfunction. However, information on perchlorate contamination of consumer foods in Taiwan is limited. This study investigated perchlorate levels in 310 food samples belonging to 12 food groups collected from Taiwanese markets. A probabilistic risk assessment was conducted to assess the related exposure to Taiwanese people. Perchlorate was detected in 65% of the samples and high levels were identified in certain plant-origin, fruit, and processed food samples. A probabilistic approach was used to estimate daily dietary dose (Monte Carlo–estimated 95th percentile dietary exposure [MCS 95]) by using the Taiwan National Food Consumption database for 14 sex/age groups. The highest and lowest average daily doses (ADDs) were in the age groups of >65 years (MCS 95 = 3.60/3.90 [male/female] μg/kg bw/day) and 16–18 years (MCS 95 = 1.70/1.47 [M/F] μg/kg bw/day), respectively. The 95th percentile of the hazard index of exposure to perchlorate of all sex/age groups far exceeded the tolerable daily intake (0.3 μg/kg bw/day) and reference dose (0.7 μg/kg bw/day) set by the European Food Safety Authority and US EPA, respectively, but it was lower than the provisional maximum tolerable daily intake (10 μg/kg bw/day) suggested by the Joint FAO/WHO Expert Committee on Food Additives. The intake quantity and concentrations of perchlorate from vegetables, fruits, and whole grains are the critical contributors for the ADDs and integrated risk of dietary exposure to perchlorate. Long-term exposure through diets should be considered, instead of focusing on individual EDC during dietary risk assessment in specific populations. Furthermore, cumulative risks for exposure to multiple contaminants, particularly those causing thyroid adverse effects, may be higher than that from perchlorate exposure alone.

Contents of Boric Acid in Noodles and Processed Foods

Boric acid is commonly used as pesticides, antifungal and antiseptics. It was also used as a food preservative to prolong the shelf life and enhance the food texture. In Malaysia, the addition of boric acid during food processing is prohibited due to its detrimental effect on health. In this study, noodles and fish-based processed food from different manufacturers were analysed for their boric acid concentrations by using the curcumin method. The results showed that there was high concentration of boric acid found in the noodles and fish-based processed food samples. The amount of boric acid detected in yellow noodles varied over the four weeks and amongst manufacturers. A similar pattern was also observed for ‘kuey teow’ (flat rice noodle) and ‘kolok’ noodle. The highest amount of boric acid concentrations was found in ‘kuey teow’ followed by yellow noodles and ‘kolok’ noodle. There was also inconsistency in the concentration of boric acid in fish cakes, fish balls and crab sticks. For fish-based products, crab stick contained the highest amount of boric acid followed by fish ball and fish cake. Even though the addition of boric acid to food is banned in Malaysia, the results of this study showed that boric acid is still being used as a food preservative in food manufacturing.

Rapid detection of porcine DNA in processed food samples using a streamlined DNA extraction method combined with the SYBR Green real-time PCR assay

A specialized DNA extraction method and a SYBR Green quantitative polymerase chain reaction (SyG-qPCR) assay were combined to generate a ready-to-use kit for rapid detection of porcine admixtures in processed meat products. Our qPCR assay utilized repetitive LINE-1 elements specific to the genome of Sus scrofa domesticus (pig) as a target and incorporated internal controls. We improved the genomic DNA extraction method, and reduced extraction times to the minimum. The method was validated for specificity, sensitivity (0.001% w/w) and robustness, and values were compared with those of a commercially available kit. We also tested our method using 121 processed food products and consistently detected amplification only in samples containing pork. Due to its efficiency and cost-effectiveness, our method represents a valuable new method for detecting food adulteration with pork that is superior to existing quality control approaches.

Development of ELISA Method for Detecting Crustacean Major Allergen Tropomyosin in Processed Food Samples

Crustacean aquatic products were recognized as allergenic food source and tropomyosin (TM) was identified as putative major allergen. At present, the most effective way to control allergenic incidence was avoidance of causative dietary source. This study reports the development of sandwich ELISA for effective detection of TM in suspected food sources by pairing two TM-specific polyclonal antibodies obtained from different species. The LOD was identified as 6.8 ng mL−1, with high specificity to the TM of shrimp and crab. No cross-reactivity was observed with the TM of fish, poultry, and mammalian. The mean recoveries in food matrices were range from 87.96 to 118.77%, by both intra- and inter-assay systems with coefficients of variation of < 10% and < 25%, respectively. The sandwich ELISA can be effectively applied for detection of TM in commercial products available in the market. It facilitates the allergen labeling and management for allergenic crustacean food products by both manufacturing and regulatory agencies.

Occurrence of perchlorate in processed foods manufactured in China

Perchlorate has been recognized as a new threat to the environment and foods, which may cause serious health problems. The information on perchlorate contamination in water and food samples in China is limited. The aims of this study were to acquire the baseline contamination levels of perchlorate in 660 processed food samples, representing 11 food categories manufactured in the Beijing-Tianjin- Hebei (BTH) region in China, and assess its health risk to the consumers. Among the samples analyzed, 574 samples contained perchlorate, and the concentrations ranged from below limit of quantitation (LOQ) to 53.8 μg/kg depending on the product. The mean concentrations of perchlorate in all the samples analyzed was 6.1 μg/kg. Based on maximum exposure scenario obtained in this study, the estimated daily intakes (EDIs) of total 11 processed food groups for Beijing, Tianjin and Hebei adults group were 488.5, 523.8 and 501.2 ng/kg bw/day, respectively. The levels are lower than the reference dose (RfD) value (700 ng/kg bw/day) suggested by the United States National Academy of Science (U.S. NAS). This result suggests a limited health risk to BTH region adults due to perchlorate exposure via processed food.

Development of a new fluorescent probe for cysteine detection in processed food samples.

Cysteine is a crucial amino acid, found in a huge amount in protein-rich foods. We focused our research to determine the amount of free cysteine consumed highly in foods such as pork, beef, poultry, eggs, dairy, red peppers, soybeans, broccoli, brussels sprouts, oats, and wheat germs. A newly designed carbazole-pyridine-based fluorescent probe (CPI) has been introduced for quantitative estimation of cysteine (Cys) with a "turn on" fluorescence in some popular processed food samples chosen from our daily diet. CPI shows both naked eye and UV-visible color changes upon interaction with cysteine. The binding approach between CPI and Cys at biological pH has been thoroughly explored by UV-visible and fluorescence spectroscopy. From Job's plot analysis, 1:1 stoichiometric reaction between CPI and Cys is observed with a detection limit of 3.8μM. NMR, ESI mass spectrometry, and time-dependent density functional theory (TD-DFT) study enlightens the formation of more stable product CPI-Cys. The "turn on" response of the probe CPI occurs due to the interruption of intra-molecular charge transfer (ICT) process upon reacting with cysteine. Moreover, CPI is a very stable, cost-effective compound and exhibits excellent real-time selectivity towards Cys over all other comparative biorelevant analytes. Interestingly, our proposed method is much advantageous as it is able to estimate cysteine predominantly by screening out other comparative biocomponents found in different protein-rich foods.

Acrylamide in daily food in the metropolitan area of Hanoi, Vietnam

ABSTRACTAcrylamide, a colourless and odourless crystalline solid, formed via the Maillard reaction in food, has been reported with harmful properties for humans, such as toxicity and carcinogenicity. Three hundred and four processed food samples from 17 product types, collected in Hanoi, Vietnam, were analyzed by LC-MS/MS to measure the acrylamide concentration. The limit of detection (LOD) and the limit of quantification (LOQ) of acrylamide were 1 µg Kg−1 and 3 µg Kg−1, respectively. Effectively, the highest acrylamide content is usually found in processed food, which is one of the primary reasons of increased acrylamide content in food. All French fried samples contained acrylamide above 500 µg kg−1. Acrylamide concentration in non-fried noodle, vermicelli, rice noodle, phở, dried vegetable, and rice cracker is lower than in potato chips, fried potatoes, fried cake, and fried noodles. The results could be helpful to estimate exposure and risk assessment of acrylamide in Vietnam.

Establishment of a method for determining the origin of glutamic acid in processed food based on carbon and nitrogen stable isotope ratios

We developed a discriminant method based on the stable isotope ratio of carbon and nitrogen (δ13C and δ15N) to evaluate whether monosodium glutamate (MSG) is used in processed food samples. δ13C measurements were performed by elemental analyzer/isotope-ratio mass spectrometry (EA/IRMS) for on glutamic acid isolated from samples at high purity, and δ15N measurements were performed by gas chromatography/combustion/IRMS (GC/C/IRMS) following the purification and derivatization steps. By applying these methods, the δ13C and δ15N values for glutamic acid present in a wide variety of processed foods were obtained. Subsequently, discriminant analysis, which is a statistical analysis method, was performed by using the δ13C and δ15N values from seasoning MSG and glutamic acid from foodstuffs of known origin, and the discriminant function was derived. By substituting the measured δ13C and δ15N values of processed food samples into this discriminant function and classifying samples into two groups, seasoning MSG (the seasoning group) and glutamic acid in foodstuffs (the foodstuff group), we determined whether seasoning MSG had been used in the processed food samples. As a result, the accuracy of distinguishing between the seasoning group and the foodstuff group was very high, i.e., 96.2%, indicating that the proposed method is a highly robust and accurate method for determining whether seasoning MSG has been used in for processed foods.

English

Cultivation and commercial utilization of genetically modified (GM) crops has significantly increased in many parts of the world and particularly in developing countries where food security is a challenge. Despite stringent regulations requiring that food made from GM foods should be properly labelled, evidence of unlabelled foods made from GM crops sold in local markets in many of these countries is increasing. This challenge provides the justification for the development of a reliable, accurate and effective screening method. Polymerase chain reaction (PCR)-based method for detection of specific genes in GM crops is a common method used in many parts of the world. This study adapted a PCR-based technique to screen for the presence of specific DNA markers of genetic modification in finished maize and soya products collected from selected supermarkets and local markets across Nigeria. Results obtained indicated that 26.7% of samples tested contain GM specific genes. GM specific genes were also detected in some made-in-Nigeria processed food samples. The findings indicate that products made with GMO materials have entered the food chain in Nigeria at a modest scale and identifies the need for capacity building in techniques for GMO detection for regulatory agencies in Nigeria.&nbsp; &nbsp; Key words: Genetically modified (GM) organism, GM maize, GM soy, polymerase chain reaction (PCR), CaMV35S, Nigeria.

Comparison of real-time PCR methods for quantification of European hake (Merluccius merluccius) in processed food samples

The quantification of species in commercial products is limited by analytical shortcomings, as most of them provide semiquantitative results. An exception is real-time PCR, which can provide quantitative results using hybridization probes. In the present work, this technique has been applied to the absolute, absolute-relative and relative quantification of the most valued hake species in European markets, Merluccius merluccius (European Hake). The best quantification results for this species in binary mixtures with non-target species (Merluccius capensis) and using a species-specific real-time PCR MMER_VIC system was achieved using a relative quantification approach (MLL as reference system). Absolute quantification using the MLL nuclear system has been demonstrated as appropriate for the quantification of the Merluccius genus in food model samples. This study reveals the impact of different reference systems (MLL and HAKE) in the absolute-relative and relative quantification approaches, showing that the nuclear MLL system performed better than the mitochondrial HAKE system.

Phylotype-Level Profiling of Lactobacilli in Highly Complex Environments by Means of an Internal Transcribed Spacer-Based Metagenomic Approach.

The genus Lactobacillus is a widespread taxon, members of which are highly relevant to functional and fermented foods, while they are also commonly present in host-associated gut and vaginal microbiota. Substantial efforts have been undertaken to disclose the genetic repertoire of all members of the genus Lactobacillus, and yet their species-level profiling in complex matrices is still undeveloped due to the poor phylotype resolution of profiling approaches based on the 16S rRNA gene. To overcome this limitation, an internal transcribed spacer (ITS)-based profiling method was developed to accurately profile lactobacilli at the species level. This approach encompasses a genus-specific primer pair combined with a database of ITS sequences retrieved from all available Lactobacillus genomes and a script for the QIIME software suite that performs all required steps to reconstruct a species-level profile. This methodology was applied to several environments, i.e., human gut and vagina and the ceca of free-range chickens, as well as whey and fresh cheese. Interestingly, the data collected confirmed a relevant role of lactobacilli present in functional and fermented foods in defining the population harbored by the human gut, while, unsurprisingly perhaps, the ceca of free-range chickens were observed to be dominated by lactobacilli characterized in birds living in natural environments. Moreover, vaginal swabs confirmed the existence of previously hypothesized community state types, while analysis of whey and fresh cheese revealed a dominant presence of single Lactobacillus species used as starters for cheese production. Furthermore, application of this ITS profiling method to a mock Lactobacillus community allowed a minimal resolution level of <0.006 ng/μl.IMPORTANCE The genus Lactobacillus is a large and ubiquitous taxon of high scientific and commercial relevance. Despite the fact that the genetic repertoire of Lactobacillus species has been extensively characterized, the ecology of this genus has been explored by metataxonomic techniques that are accurate down to the genus or phylogenetic group level only. Thus, the distribution of lactobacilli in environmental or processed food samples is relatively unexplored. The profiling protocol described here relies on the use of the internal transcribed spacer to perform an accurate classification in a target population of lactobacilli with a <0.006-ng/μl sensitivity. This approach was used to analyze five sample types collected from both human and animal host-associated microbiota, as well as from the cheese production chain. The availability of a tool for species-level profiling of lactobacilli may be highly useful for both academic research and a wide range of industrial applications.

Microbial Analysis of Processed Foods Stored in Domestic Refrigerators of Selected Eateries in Ile-Ife, Osun State, Nigeria

Consumption of contaminated refrigerated foods is increasing the incidence of food-borne diseases globally. However, there is paucity of data on prevalence of microbes associated with these foods from Osun State, Nigeria, thus, the need for isolation and characterization of microbes associated with refrigerated foods from this region. A total of 80 processed food samples were collected aseptically and refrigerated for four days. Samples were analyzed for the presence of bacteria and fungi while antibiotic resistance patterns of bacterial isolates were determined using standard methods. Mean bacterial count ranged from 7.0 x104 to 3.7 x105 cfu/ml with highest bacterial count of 3.7 x 105 cfu/ml obtained from melon soup sample, while least count of 7x104 cfu/ml was obtained from cooked meat. Fungal count ranged from 2.0 x 102 to 5.6 x103 sfu/ml with cooked beans having the highest count of 5.6 x 103 sfu/ml. The bacteria that were isolated from refrigerated processed food samples include Corynebacterium kutscheri (47.05%), Bacillus spp (14.70%), Staphylococcus aureus (11.76%), Lactobacillus fermenti (5.8%), Aeromonas hydrophila (5.8%), Pseudomonas spp (5.88%), Lactobacillus casei (2.94%), Lactobacillus delbrueckii (2.94%) and Citrobacter freundii (2.94%), while fungi isolated were Aspergillus fumigatus (24.56%), Aspergillus niger (21.05%), Aspergillus flavus (14.04%), Aspergillus brevipes (14.04%), Mucor spp (7.02%), Penicillium spp (8.77%) and Saccharomyces spp (10.53%). Corynebacterium kutscheri had the highest resistance of 17(37%) while Lactobacillus casei showed no resistance (0%) to the antibiotics used. This study showed high bacterial and fungal counts from the analyzed samples, hence, the need to ensure hygienic food processing and refrigerating conditions.

Extraction and reliable determination of acrylamide from thermally processed foods using ionic liquid-based ultrasound-assisted selective microextraction combined with spectrophotometry

ABSTRACTAcrylamide (AAm) is a carcinogenic chemical that can form in thermally processed foods by the Maillard reaction of glucose with asparagine. AAm can easily be formed especially in frequently consumed chips and cereal-based foods depending on processing conditions. Considering these properties of AAm, a new, simple and green method is proposed for the extraction of AAm from thermally processed food samples. In this study, an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF4]) as extractant was used in the presence of a cationic phenazine group dye, 3,7-diamino-5-phenylphenazinium chloride (PSH+, phenosafranine) at pH 7.5 for the extraction of AAm as an ion-pair complex from selected samples. Under optimum conditions, the analytical features obtained for the proposed method were as follows; linear working range, the limits of detection (LOD, 3Sb/m) and quantification (LOQ, 10Sb/m), preconcentration factor, sensitivity enhancement factor, sample volume and recovery% were 2.2–350 µg kg−1, 0.7 µg kg−1, 2.3 µg kg−1, 120, 95, 60 mL and 94.1–102.7%, respectively. The validity of the method was tested by analysis of two certified reference materials (CRMs) and intra-day and inter-day precision studies. Finally, the method was successfully applied to the determination of AAm levels in thermally processed foods using the standard addition method.

A simple and sensitive two-tube multiplex PCR assay for simultaneous detection of ten meat species

A sensitive and reliable technique for meat species identification is required to prevent food adulteration, particularly in meat production. This work developed an optimized multiplex PCR assay for simultaneous identification of five commonly consumed and five commonly banned meat species in meat products. We designed primers that specifically amplified mitochondrial ATPase subunit 8 gene regions of different lengths of bovine, ovine, swine, chicken, turkey, cat, dog, mouse and human DNAs. The developed multiplex PCR assay proved to be specific, sensitive down to 30pg DNA per reaction, reproducible and economical. It could be used with a variety of raw meats and processed food samples and is easily applicable in a routine laboratory analysis without specific sophisticated equipment.

Direct quantitation of the preservatives benzoic and sorbic acid in processed foods using derivative spectrophotometry combined with micro dialysis

The preservatives benzoic acid and sorbic acid are generally quantified with separation techniques, such as HPLC or GC. Here we describe a new method for determining these compounds in processed food samples based on a narrowness of the UV–visible spectral band width with derivative processing. It permits more selective identification and determination of target analytes in matrices. After a sample is purified by micro dialysis, UV spectra of sample solutions were measured and fourth order derivatives of the spectrum were calculated. The amplitude between the maximum and minimum values in a high-order derivative spectrum was used for the determination of benzoic acid and sorbic acid. Benzoic acid and sorbic acid levels in several commercially available processed foods were measured by HPLC and the proposed spectrometry method. The levels obtained by the two methods were highly correlated (r2>0.97) for both preservatives.

Development of a Polymerase Chain Reaction-Temporal Temperature Gradient Gel Electrophoresis Assay for Identification of Salmonella enterica Subspecies enterica Using a Hypothetical Non-specific Endonucleas S. entericae Gene Sequence

Background: Salmonella is one of the major agents of food-borne diseases that cause severe illness in humans. The conventional detection methods of these bacteria are time-consuming with low sensitivity and specificity, which limit their applications. Therefore, developing more rapid and accurate methods is urgently required in food safety programs. Objectives: In this study for the first time, polymerase chain reaction-Temporal temperature gradient gel electrophoresis (TTGE) was optimized for the identification of Salmonella enterica subspecies enterica serovars in processed food samples using a single-copy sequence. Methods: DNA was isolated from pure cultures of Salmonella and non-Salmonella strains. The single copy target sequence was selected and amplified by employing the polymerase chain reaction (PCR) with specific primers, designed in this study, and their specificity and sensitivity were determined. The TTGE parameters, especially the temperature gradient and the time of reaction, were optimized and then this method was applied to investigate spiked food samples. Results: The PCR detection sensitivity was recorded as 12 × 103 CFU/mL in artificially-contaminated food samples. The best resolution was observed at a temperature gradient from 62.5 to 67.5°C, with a ramp rate of 1°C/hour and electrophoresis for 5 hours at a constant voltage of 130 V. The TTGE patterns obtained from the artificially-contaminated samples were similar with the respected standard bacteria strains. The optimized TTGE protocol resulted in the separation of the same length PCR products into different band positions on the polyacrylamide gel. Conclusions: By optimization of PCR-TTGE and determination of distinct band pattern for standard bacteria, this method can be used as a fast screening test to investigate the presence of S. enterica, subspecies enterica, directly in food samples.

Pork detection in binary meat mixtures and some commercial food products using conventional and real-time PCR techniques.

Pork DNA was detected in meat mixtures using both conventional PCR and real-time PCR (RT-PCR). Thirty meat mixtures containing beef, chicken, camel, rabbit, goat and sheep with varying percentage of pork (0%, 1%, 5%, 10%, and 20%) and 75 commercial food products, were analyzed using conventional and RT-PCR to determine the presence of pork DNA. Pork DNA standard curves and cycle threshold (Ct) values were used for quantification. The detection limits for pork DNA in the mixtures were 0.22, 0.047, 0.048, 0.0000037, 0.015ng/μl respectively. Unlike conventional PCR, RT-PCR detected pork DNA in nine processed food samples [chicken sausages (2), chicken luncheon (2), turkey meat loaf, milk chocolate with soft nougat, jelly, cake, and candies] at pork DNA concentrations of 0.0001ng/μl or less.

In-capillary derivatization with o-phthalaldehyde in the presence of 3-mercaptopropionic acid for the simultaneous determination of monosodium glutamate, benzoic acid, and sorbic acid in food samples via capillary electrophoresis with ultraviolet detection

For the rapid simultaneous determination of monosodium glutamate (MSG), benzoic acid (BA), and sorbic acid (SA) in canned food and other processed food samples, we developed a method that combines in-capillary derivatization with separation by capillary electrophoresis. This method employs the rapid derivatization of MSG with o-phthalaldehyde (OPA) in the presence of 3-mercaptopropionic acid (3-MPA) and enables the detection of the resulting OPA-MSG derivative and of non-derivatized BA and SA at 230nm. The composition of the background electrolyte and the parameters of derivatization and separation are as follows: 25mM borax containing 5mM OPA and 6mM 3-MPA, separation voltage 25mV, injection at 30mbar for 20s, and column temperature 25°C. Because of the high reaction rate and suitably adapted effective electrophoretic mobilities, band broadening due to the derivatization reaction at the start of the separation process is kept to a minimum. The optimized method is validated with respect to LOD, LOQ, linearity, recovery, and precision. This method can be applied to real samples such as soy, fish, oyster and sweet and sour chili sauces after application of appropriate clean-up steps. Mechanisms of zone broadening and zone focusing are discussed showing the validity of the employed theoretical approach regarding the dependence of the peak shape for OPA-MSG on the concentration of MSG in the sample.