j khandaghi

One of the significant contaminants in animal-derived foods, such as milk, is antibiotic residues, which put consumers' health at risk. Monitoring the amount of antibiotic residue in milk is crucial in order to alert the nation's health authorities and in this regard, several researches have been conducted for determination of different antibiotic residues in milk using various traditional and chromatographic methods. In this study, an efficient method for determining the residual levels of some sulfonamides in pasteurized milk was developed and presented.

After dispersive solid-phase extraction combined with air-assisted liquid-liquid microextraction of analytes, the residues of sulfadiazine, sulfamethoxazole, and sulfamethazine in the pasteurized milk were determined using HPLC with a diode array detector. Following the evaluation of the effective factors in the extraction and optimizing them, the validation of method was carried out by calculating analytical parameters such as linear range, LOD, LOQ, repeatability, and extraction recovery.

In the developed two-step extraction method, satisfactory figures of merit were obtained, therefore the method's linearity was shown with a coefficient of determination higher than 0.995. The limits of detection and measurement were less than 1.2 and 3.2 ng ml-1, respectively, which is less than the MRLs established for these antibiotics in milk. The analysis of real samples showed the presence of sulfamethoxazole in three milk samples in concentrations of 13±0.1, 9±0.2 and 9.6±0.5 ng ml-1 and no other antibiotics were discovered in the examined samples.

Overall, the established approach is a sensitive, accurate and reliable method and has high efficiency in determining selected antibiotics in milk samples.

One of the frequent chemical contaminants in honey that can harm consumers' health is the group of polycyclic aromatic hydrocarbons. In the present study, combination of liquid-phase extraction method with magnetic ionic liquids based dispersive liquid–liquid microextraction was developed to analyze polycyclic aromatic hydrocarbons in honey samples using high-performance liquid chromatography.

Following two-step extraction of acenaphthene, phenanthrene, anthracene and pyrene from honey samples, effective extraction parameters such as the type and volume of extracting solvent, ionic strength and vortexing time of the sample were optimized. To validate the proposed method, analytical parameters such as the linear range, limit of detection (LOD), limit of quantification (LOQ), reproducibility (RSD%) and extraction recovery percent (ER%) of the target compounds were calculated.

After using the optimized analytical method, optimal analytical characteristics such as LOD in the range of 0.13 to 0.27 ng/g, RSD% in the range of 2.9 to 6.2 and ideal ER% in the range of 74 to 82% were achieved. In addition, high accuracy of the developed method was supported by the fact that sample matrices included no detrimental effects on the extraction of the target analytics. Analysis of the real samples showed the presence of pyrene in two honey samples with quantities of 11.3 ±0.2 and 12.3 ±0.5.

The suggested approach is valid, as indicated by favorable analytical parameters such as high sensitivity and accuracy as well as an ideal ER%. Moreover, use of green solvents can be addressed as one of the advantages of the developed method.

Different types of antibiotics are used indiscriminately in animal husbandry for the growth and treatment of livestock, which cause accumulation of antibiotic residues in livestock products such as milk. Long-term consumption of milk contaminated with antibiotic residues above the permissible limits is harmful to human health, causing antibiotic resistance problems. Therefore, monitoring of antibiotic residues in milk and dairy products is particularly important.

In this study, temperature-controlled ionic liquid-assisted dispersive liquid-liquid microextraction  method was developed for the extraction of amoxicillin, cloxacillin and erythromycin residues from cow milk and their assessment were carried out using high-performance liquid chromatography equipped with a diode array detector. Furthermore, effects of various parameters on the extraction efficiency such as volume of precipitating agent and vortexing time, type and quantity of extracting solvent, effects of salt addition and temperature of aqueous solution were optimized.

Analysis of milk samples showed presence of amoxicillin in eight milk samples, all of which included values greater the permissible limits. No other antibiotics were detected in the milk samples. The suggested method included high efficiencies in extracting the target antibiotic residues from milk samples. Therefore, repeatability of the method based on relative standard deviation proportion included 3–4.5. Under optimal conditions, extraction recoveries were in range of 78–87% and the limits of detection and quantification less than 1.1 and 3.7 ng/ml were reported, respectively.

The developed method is appropriate for the determination of selected analytics in cow milk and its detection limit is lower than the maximum residue limits for the residues of these antibiotics.

Use of various pesticides to protect agricultural products increases likelihood of residues of these compounds entering the human body through the consumption of food products. In this study, an efficient method was developed for the extraction and preconcentration of organophosphorus pesticides from packed juice samples using gas chromatography-nitrogen-phosphorus detector.

In this study, a combination of dispersive solid-phase extraction and dispersive liquid-liquid microextraction was used for the extraction of pesticides from fruit juice samples. Chitosan-Ni/Fe layered double hydroxide composite was synthesized and used after characterization as adsorbent in dispersive solid-phase extraction step. To achieve high extraction efficiency, effects of various factors in the two extraction stages were investigated and optimized.

Interaction of chitosan with the produced layered double hydroxide was verified using Fourier-transform infrared spectroscopy and its crystallographic structure was verified using X-ray diffraction. In addition, porous structure of the synthesized adsorbent, indicating large surface areas and high extraction capacities, was verified via morphological study of the composite. Developed extraction method was successfully carried out on juice samples as the sample matrix included no significant effects on the separation of analytes and limits of detection and limit of quantification of the method included 0.011–0.019 and 0.043–0.063 ng/ml, respectively. Linear range of the suggested method was wide (0.36–0.250) and the method included an appropriate precision with RSD% less than 5.6 for intra and inter-day precisions. Values ​​were also desirable for the extraction efficiency (72–76%).

In general, dispersive solid-phase extraction in combination with dispersive liquid-liquid microextraction included a wide linear range and appropriate repeatability. In addition, this method included desirable values for enrichment factor, limits of detection and extraction efficiency and hence is recommended for the assessment of target pesticides in juice samples.

Safety control of traditional raw milk cheese such as Pot cheese is of special importance. Although enterococci can play beneficial probiotic or technological properties in cheese and their use in food is the subject of debate due to evidence of pathogenicity and antibiotic resistance.

In the present study, after isolation and morphological and biochemical identification of enterococci isolated from 50 samples of traditional Pot cheeses in West Azerbaijan province, the antibacterial properties of the isolates were determined by well diffusion method and the resistance pattern to 12 common clinical antibiotics was evaluated using disk diffusion method. The hemolytic properties of the isolates were also investigated.

The results showed the presence of enterococci in 74% of the Pot cheese samples. Among the identified species, Enterococcus faecalis and Enterococcus faecium had the highest frequency with 44.7% and 37.2%, respectively. The highest inhibitory effects of isolates were recorded for Listeria monocytogenes (83.7%). Studies showed that over 80% of isolates were sensitive to eight common clinical antibiotics, including vancomycin. Also, all enterococcus isolates lacked hemolysis activity.

This study showed that traditional jar cheese is a rich source of Enterococcus bacteria with antimicrobial activity and high sensetive to common antibiotics such as vancomycin. If more safety aspects are studied and other probiotic properties are evaluated, these isolates can be used as a source of native probiotic bacteria in other fermented products.

Food quality and safety control is an important part of the public health assessment of food adulteration has been a key issue in recent years. Cream is a product containing milk fat and is one of the most expensive and widely consumed edible fats, which is often targeted for cheating by mixing various vegetable oils with natural milk fats. A way to detect this type of fraud is to assess phytosterols in this dairy product.

In this study, homogeneous liquid-liquid extraction method combined with dispersive liquid-liquid microextraction method was used for the extraction of stigmasterol, brassicaestrol, compesterol and β-sitestrol from animal cream samples. Samples were analyzed using gas chromatography-flame ionization detection method. To achieve high efficiency, effects of various factors in each extraction step, including type and volume of the extraction solvent, volume of the separating agent, speed and duration of centrifugation in the homogeneous liquid-liquid extraction step were investigated and optimized. Moreover, type and volume of the extraction solvent and salting effects in the dispersive liquid-liquid microextraction step were investigated and optimized as well.

The suggested method was successfully carried on on cream samples. Limit of detection and limit of quantification of the method were in ranges of 0.92–2.1 and 2.1–6.4 ng/g, respectively. Method included a proper precision with relative standard deviation of less than ≤ 8.8 for intra and inter-day precisions. Results showed that the total phytosterol content in 21 samples (70%) was more than 3%, contrary to the legal limits by the Institute of Standards and Industrial Research of Iran.

Results of this study have verified that the suggested method is simple and reliable, including short analysis time and high ability to extract and measure phytosterols from animal cream samples.

To improve the quality and increase the shelf life of agricultural products, many pesticides are widely used. Although the use of pesticides in agricultural applications provides a wide range of beneficial effects, overuse of these substances results in their accumulation in soil, surface water, and foods. The analysis of pesticide residues is thus very important for the health of consumers. In this study, a combined extraction method of QuEChERS based on deep eutectic solvents and DLLME method for the extraction of Hexaflumuron, Chlorfluazuron, Flufenoxuron, Diafenthiuron, and Diflubenzuron benzoylurea pesticides from fruit samples of grape, apple, cherry, apricot, and orange and then analyzing them using high-performance liquid chromatography with diode array detector is presented. According to the results, the proposed method is simple, reliable, and inexpensive with low organic solvent consumption and has a short analysis time, and indicates good values extraction efficiency, so that under optimal conditions, limits of detection and quantification were obtained in the range of 3.3-6.5 and 11.2-22.2 ng/ml, respectively. Recovery rates and enhancement factors ranged from 52% to 88%. In actual samples, only Flufenoxuron insecticide present in one grape sample was detected at 17 0.5 ng/ml.

Citrus lemon and lime juice, which contain high levels of vitamin C and natural antioxidant in the form of polyphenols, have a special place in the food basket of Iranian households. Flavonoids are among the polyphenolic compounds and Eriocitrin, Naringin and Hesperidin are among the most important flavonoids. Investigating the amount and type of polyphenols and flavonoids in this food is one of the tools to discover the authenticity of this juice.

In this research, 65 samples of lime juice (42 samples of packed lime juice and 23 samples of bulk lime juice) were purchased from Tabriz and total amount of phenolic compounds were determined using spectrophotometry. Also, the quantities of Eriocitrin, Naringin and Hesperidin were analyzed using liquid chromatography method in order to investigate possible counterfeiting.

The average amount of total polyphenolic compounds of packed and bulk juices were 275 and 303 mg/l, respectively and totally, 9 samples (13.8%) did not conform to the Institute of Standards of Iran rules and were considered as not consumable. Regarding flavonoids, the results showed that the average amount ​​of Eriocitrin, Naringin and Hesperidin were 17.32, 28.31 and 80.44, respectively. Accordingly, 33 samples (50.78%) were not consistent with the Institute of Standards of Iran rules. In the present study, the reason for the non-standardization of most lemon juice samples (78.8%) was presence of the Naringin flavonoids.

In determining flavonoid compounds in comparison with the method of measuring total phenolic compounds, 24 more samples of lime juice (36% of samples) were found not to be standard, so due to the increasing adulteration that occurs in the various food industries, it is imperative that food health monitoring institutions use new and effective methods for food authentication to ensure community health.

Nowadays, consumers are demanding more accurate and clear food information than ever before, and meat products are no exception. Given the relatively high cost of raw meat, the possibility of adulteration is not unthinkable. The importance of detecting fraud meat products is due to the inclusion of other types of meat or cheap carcass components or the non-compliance of the ingredients listed in the product label. It is important to identify frauds in meat products for economic, security, religious and health reasons, so institutions concerned with the quality and health of food products must monitor this issue in various and precise ways.

In this study, chemical properties (fat, protein, carbohydrate, ash and moisture contents) of 58 samples of meat products offered in Tabriz were evaluated by the methods mentioned in the Institute of Standards and Industrial Research of Iran. Also, the meat authenticity of 47 samples of raw meat and red meat products in terms of mixing meat or other parts of chicken carcass with them was investigated using PCR technique.

The results showed that 41.38% of the tested samples had values ​​contrary to the permissible limits set by the Institute of Standards and Industrial Research of Iran. Also, cases of fraud in the samples through mixing poultry meat in the samples were found whether in standardized products such as processed and semi-processed products or in raw meat samples, so that overall, 87.23% of the obtained samples were not confirmed for product authenticity.

This study showed that fraud and incorrect information on the label of red meat products in terms of poultry meat adulteration in them in Tabriz city is very high and this fact further reveals the need for accurate, continuous and regular monitoring of health institutions on this high-consumption food product.

The measurement of harmful substances that may enter the food has particular importance. Pesticides are one of the most important compounds that are wieldy used in agricultural activities. Despite the positive effects of the application of pesticides in agriculture, many pesticides are harmful to the environment and are known or suspected to be toxic to humans. Pyrethroid pesticides are common pesticides used in agricultural and personal care products and due to their high efficiency in controlling different pests they widely used. In the present work, an efficient and reliable microextraction method based on temperature-induced homogeneous liquid-liquid microextraction developed for the extraction of Delthamethrine, Biphenthrine, Permethrin, Cyhalothrin and Cypermethrine pyrethroid pesticides from potato, tomato, lettuce and onion and then its analyses performed using gas chromatography-mass spectrometry method. The optimized method validated with recoveries ranging from 56 to 83%. The limits of detection were in the range of 4.3-9.4 ng mL-1, indicating high repeatability of the proposed method in the extraction and analysis of pyrethroid pesticides. Other advantages of this method include low cost and simplicity, low organic solvents consumption, and short analysis time.

Crops such as fruits as raw materials for the production of fruit juices are affected by different pests that are regularly used to combat these agents in agriculture activities. Some of these substances not only remain on the surface of crops but also penetrate their tissues, as most of the crops exposed to pesticides contain amounts of pesticide residues that enter the consumer's body along with foods. For this reason, the use of precise and efficient methods in evaluating the residuals amounts of these compounds in food products is of great value. In this research, a combination of air-assisted liquid-liquid microextraction and liquid-liquid microextraction with solidification of floating organic drop methods has developed for extraction and preconcentration of some of the widely used organophosphorus pesticides used in Iran (Diazinon, Chlorpyrifos, Phosalone,  Parathion- methyl and Azinphos-methyl) from juice samples before their analysis by high-performance liquid chromatography. Under optimal conditions, 32 μl of menthol as the extraction solvent and 75 μl acetonitrile as dispersive solvent at a temperature of 60 °C used to extract the analytes. The proposed method is simple, reliable, and inexpensive and yields optimal values ​​for extraction efficiency so that under optimized conditions the recoveries ranging from 61 to 79%. RSD% was in range 4.6 to 6.9, indicating high reproducibility of the proposed method. Other advantages of this method include low organic solvents consumption and short analysis time.

With the significant increase in bottled natural mineral water production and consumption over the last decade in our country, there has been a growing concern over the microbiological quality of such products. The purpose of the present study was to analyze various bottled natural mineral waters sold in Tabriz. In this study, 150 samples of such products were examined for aerobic colony count, coliforms, fecal coliforms, Escherichia coli, fecal streptococci, Clostridium perfringenes and Pseudomonas aeruginosa. Aerobic colony count pseudomonas and clostridium were determined using membrane filtration method and most probable number (MPN) method was used for determining coliforms and fecal streptococci. The results indicated that in 25.3% of the samples there was no microbial growth in plate count agar media and 2% of the samples were contaminated with high levels of aerobic colony count (more than 20 bacteria/ ml). Furthermore, of the 72.6% of samples with acceptable aerobic colony count, 2.75%, 1.83%, 2.75% and 0.91% were contaminated with coliforms, fecal streptococci, pseudomonas and clostridium respectively.