Showing papers in "Food Analytical Methods in 2011"

Antioxidant Activity of Pink-Flesh Guava (Psidium guajava L.): Effect of Extraction Techniques and Solvents

Abstract: The effect of commonly used techniques and solvents in the antioxidant activities of pink-flesh guava fruit were studied. The extraction techniques compared were homogenization, shaking, sonication, magnetic stirring, and maceration for 1, 2, and 3 days. The solvent systems used were methanol, ethanol, and acetone at three different concentrations (50%, 70%, and 100%) and with 100% distilled water. The antioxidant activity of the fruit was evaluated using Folin–Ciocalteu index, ferric-reducing antioxidant power assay, and 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging capacity. Ultrasonic and homogenization were the best techniques to extract the antioxidant from guava fruit. Homogenization technique was found to be the most convenient exhaustive and time-saving extraction technique. Results showed that the extracting solvent significantly (P < 0.05) altered the antioxidant property estimations of pink-flesh guava fruit. Pure solvents were inefficient extraction media for antioxidant. Enhanced extraction yields were obtained from solvent containing higher water concentrations and 50% acetone is a recommended solvent for extracting antioxidants compounds from pink-flesh guava fruit. High correlations between phenolic compositions and antioxidant activities of pink-flesh guava extracts were observed. High levels of antioxidant activities were detected in pink-flesh guava, indicating that the fruit may serve as an excellent dietary source of natural antioxidants.

Analytical Methods for Virus Detection in Water and Food

Abstract: Potential ways to address the issues that relate to the techniques for analyzing food and environmental samples for the presence of enteric viruses are discussed. It is not the authors’ remit to produce or recommend standard or reference methods but to address specific issues in the analytical procedures. Foods of primary importance are bivalve molluscs, particularly, oysters, clams, and mussels; salad crops such as lettuce, green onions and other greens; and soft fruits such as raspberries and strawberries. All types of water, not only drinking water but also recreational water (fresh, marine, and swimming pool), river water (irrigation water), raw and treated sewage are potential vehicles for virus transmission. Well over 100 different enteric viruses could be food or water contaminants; however, with few exceptions, most well-characterized foodborne or waterborne viral outbreaks are restricted to hepatitis A virus (HAV) and calicivirus, essentially norovirus (NoV). Target viruses for analytical methods include, in addition to NoV and HAV, hepatitis E virus (HEV), enteroviruses (e.g., poliovirus), adenovirus, rotavirus, astrovirus, and any other relevant virus likely to be transmitted by food or water. A survey of the currently available methods for detection of viruses in food and environmental matrices was conducted, gathering information on protocols for extraction of viruses from various matrices and on the various specific detection techniques for each virus type.

Dispersive Solid-Phase Extraction Clean-up Combined with Dispersive Liquid–Liquid Microextraction for the Determination of Neonicotinoid Insecticides in Vegetable Samples by High-Performance Liquid Chromatography

Abstract: Dispersive solid-phase extraction (DSPE) clean-up combined with dispersive liquid–liquid microextraction (DLLME) has been developed as a new approach for the extraction of neonicotinoid insecticides in vegetable samples prior to high-performance liquid chromatography with diode array detection. In the DSPE–DLLME method, neonicotinoid insecticides were first extracted with acetonitrile from vegetable samples, followed by clean-up by a DSPE with primary secondary amine and multi-walled carbonnanotubes as sorbents. A 2.5-mL aliquot of the resulting extract was then added into a centrifuge tube containing 10 mL of water, 0.8 g NaCl, and 200-μL chloroform (as the extraction solvent) for DLLME procedure. Under the optimum conditions, the enrichment factors for the compounds were in the range between 110 and 243. The linearity of the method was in the range from 5.0 to 300 ng g−1 with the correlation coefficients (r) ranging from 0.9989 to 0.9998. The detection limits of the method were 0.5–1.0 ng g−1. The repeatability of the method expressed as the relative standard deviations by five parallel experiments at the concentration levels of 10 and 50 ng g−1 each of the neonicotinoid insecticides in tomato or cucumber samples varied from 3.6% to 5.8%. The developed method has been successfully applied for the analysis of target neonicotinoid insecticides (acetamiprid, imidacloprid, thiacloprid, and thiamethoxam) in tomato and cucumber samples. The recoveries of the method for the target neonicotinoid insecticides from the vegetable samples at spiking levels of 10.0 and 50.0 ng g−1 were in the range between 84.6% and 97.5% (n = 5).

Validation of a Duplex Real-Time PCR for the Detection of Salmonella spp. in Different Food Products

Abstract: A 5′ nuclease duplex real-time polymerase chain reaction (PCR) assay was developed and validated with various food products for the specific and fast detection of Salmonella spp. in food. The assay used previously published primers in combination with a newly developed probe targeting the invA gene. An internal amplification control, which is coamplified in a duplex PCR, was included in the assay. The analysis of 1,934 natural food samples with real-time PCR and the cultural method in parallel resulted in a relative accuracy of 100% and 99.84% respectively, depending on the enrichment procedure in which buffered peptone water and selective enrichment in Rappaport–Vassiliadis (RV) broth were employed. The duplex real-time PCR assay has proven to be a specific, sensitive and fast screening method for Salmonella spp. in food. The overall analysis time of the PCR method was approximately 28 h, in contrast to 4 to 5 days with conventional Salmonella diagnostics. The developed assay has been shown to be a reliable diagnostic tool for use in routine analysis. It has been validated thoroughly and has become an official method in Germany for the detection of Salmonella spp. in food.

Fast Quantitative Determination of Aroma Volatile Constituents in Melon Fruits by Headspace–Solid-Phase Microextraction and Gas Chromatography–Mass Spectrometry

Abstract: Since the aroma is one of the essential factors for evaluating fruit quality, a headspace–solid-phase microextraction and gas chromatography–mass spectrometry method for the identification and quantification of the aroma volatile constituents in melon fruits has been developed. Two different varieties of Cucumis melo L., reticulatus and inodorus, have been analyzed and 66 volatile compounds have been identified and quantified; among these, the impact aroma compounds are included too. The volatile compounds have been identified by linear retention index, mass spectra, standard injection, and reference data; the quantification has been carried out by the standard addition technique. The method proposed showed good linearity within the concentration range tested; the precision, CV was <15% for all the components identified, and the limits of quantification was very low for most of the components, for example, 1.7 ng/g for ethyl octanoate and 1.5 ng/g for limonene. The results emphasized each fruit variety could be distinguished by a different qualitative and quantitative volatile fraction composition; as example, reticulatus samples were characterized by a high amount of esters (192.8 μg/Kg), which were present as traces in inodorus. Sensory analysis was performed on the samples and quantitative volatile and sensory data were correlated using multivariate analysis. The developed method allowed us to obtain reliable quantitative data of the melon volatile constituents which are necessary for the fruit quality evaluation since the aroma contribution of a particular substance is assessed by knowledge of the ratio between its amount and odor threshold level.

Application of Fast Gas Chromatography and Fourier Transform Infrared Spectroscopy for Analysis of Lard Adulteration in Virgin Coconut Oil

Abstract: Lard (LD) and virgin coconut oil (VCO) share some similarities such as having transparent to yellowish color and are solid at room temperature; hence, as a consequent, LD may be a potential oil adulterant in VCO. This study highlights the application of fast gas chromatography with surface acoustic wave detector (GC-SAW system) and Fourier transform infrared (FTIR) spectroscopy combined with chemometrics to analyze the presence of LD in VCO. Binary admixtures of LD in VCO in various percentage concentrations ranging from 1% to 50% (v/v) were assayed using the fast GC-SAW system and FTIR spectroscopy. Using the fast GC-SAW system, ten different chromatogram peaks were identified as the adulterant peaks. One peak in the fast GC-SAW system chromatogram was found to have the best relationship, with a coefficient of determination (R2) value of 0.9344. Furthermore, FTIR spectroscopy coupled with partial least square (PLS) and discriminant analysis (DA) can be successfully developed for quantification and classification of LD in VCO. The results showed that PLS able to predict the LD contents in VCO with equation of \( y = 0.{999} \times + 0.00{6} \), for the correlation between actual value of LD (x) and FTIR predicted value (y) with R2 of 0.9990 at frequency regions of 3,020–3,000 cm−1 and 1,120–1,000 cm−1. DA can classify VCO and that adulterated with LD using the FTIR spectra at the same frequency regions used in quantification.

Construction and Analytical Application of Internal Amplification Controls (IAC) for Detection of Food Supply Chain-Relevant Viruses by Real-Time PCR-Based Assays

Abstract: Internal amplification controls (IACs) were constructed for incorporation into real-time nucleic acid amplification assays for bovine polyomavirus, hepatitis A virus, hepatitis E virus, human adenovirus, human norovirus genogroup I, human norovirus genogroup II, murine norovirus and porcine adenovirus. The addition of optimised amounts of IAC into the assays did not affect the limits of detection for each specific target virus. A poorly performed extraction of viral nucleic acids was simulated, and the effectiveness of IACs in identifying failed assays was demonstrated. The IACs constructed in this study can be reliably used in their specific assays to provide a robust control that can be routinely applied in the analysis of foods for viruses.

Quantification of 2-Acetyl-1-pyrroline and Other Rice Aroma Volatiles Among Indian Scented Rice Cultivars by HS-SPME/GC-FID

Abstract: A method for quantitative determination of 2-Acetyl-1-pyrroline (2AP) and other aroma volatiles using HS-solid phase micro extraction (SPME)/GC-FID in scented rice has been developed. Extraction at 80 °C for 30 min pre-incubation followed by 20-min adsorption from 1 g rice containing 300 μl of odour-free water were the optimum conditions for quantification. Calibration curves of aroma volatiles were obtained by standard addition approach. The optimised conditions were employed for quantitative analysis in 33 scented and two non-scented rice samples. Highest amount of 2AP was recorded in Indrayani Brand 2 (0.552 ppm), followed by Kamod (0.418 ppm) and Basmati Brand 5 (0.411 ppm). Rice types (Basmati, Ambemohar, Kolam, Indrayani and local) significantly contributed to the variation in 2AP, hexanal, nonanal, decanal, benzyl alcohol, vanillin, guaiacol and indole. The method developed suffices the need of rapid and reliable method for quantification of 2AP and other aroma-related volatiles from aromatic rice cultivars.

Potential Use of FTIR-ATR Spectroscopic Method for Determination of Virgin Coconut Oil and Extra Virgin Olive Oil in Ternary Mixture Systems

Abstract: The aim of this study was to investigate the feasibility of Fourier-transform infrared (FTIR) spectroscopy combined with multivariate calibrations of partial least square (PLS) and principle component regression (PCR) for analysis of virgin coconut oil (VCO) in the ternary mixture with palm oil (PO) and olive oil, and for analysis of extra virgin olive oil (EVOO) mixed with soybean oil (SO) and corn oil (CO). The spectra of individual oils and their blends with certain concentrations were scanned using horizontal attenuated total reflectance accessory at mid-infrared region of 4,000–650 cm−1. The optimal frequency regions selected for calibration models were based on its ability to give the highest values of coefficient of determination (R 2) and the lowest values of root mean standard error of calibration (RMSEC). PLS was slightly better for quantitative analysis of VCO and EVOO compared with PCR. VCO in ternary mixtures is successfully determined at frequency region of 1,200–1,000 using second derivative FTIR spectra with R 2 and RMSEC values of 0.999 and 0.200, respectively. Meanwhile, EVOO is best determined at 1,200–1,000 using first derivative FTIR spectra with R 2 and RMSEC values of 0.999 and 0.975, respectively. The results showed that FTIR spectroscopy offers accurate and reliable technique for quantitative analysis of VCO and EVOO in ternary systems. In addition, the developed method can be used for the monitoring of VCO and EVOO adulteration with cheaper oils like PO in VCO as well as SO and CO in EVOO.

Multiplex Real-time PCR for the Simultaneous Detection of Salmonella spp. and Listeria monocytogenes in Food Samples

Abstract: In this study, we have developed a rapid method for the simultaneous detection of Listeria monocytogenes and Salmonella spp. in foods, combining culture enrichment and a multiplex real-time polymerase chain reaction (PCR). The assay used two pre-existing primer-probe sets, labelled with different reporter dyes to enable the direct distinction of the original contaminating agent. Amplification efficiency and inclusivity/exclusivity of the combined assay was successfully assessed. The overall process included the culture enrichment based on the ISO standard, consisting of 24 h incubation in appropriate media (Half Fraser Broth for Listeria and buffered peptone water (BPW) for Salmonella), followed by a single DNA extraction of mixed enrichment aliquots, and real-time PCR detection of the hly and bipA genes of L. monocytogenes and Salmonella spp., respectively. An internal amplification control, co-amplified during the PCR run, was included in the assay to verify the results. The tool was evaluated with a variety of artificially inoculated samples of fresh products and ready to eat and cooked dishes, allowing the identification of the target pathogens down to 5 CFU/25 g of food sample. Moreover, the analysis saved a considerable amount of time compared to the ISO standard, being performed in less than 2 working days. Specificity, sensitivity and accuracy were satisfactorily tested by comparison to the standard methods ISO 11290-2:1998 and ISO 6579:2002, suggesting that the tool has a great potential as a reliable alternative for food safety assurance providing rapid detection of both pathogens in food samples.

Optimization of Solid-Phase Microextraction Procedure Coupled to GC-ECD for Triazole Fungicides Determination in Juice Samples

Abstract: A solid-phase microextraction (SPME) procedure followed by gas chromatography electron capture detection (GC/ECD) for the determination of triazole residues was developed. An experimental design with two steps was done. Firstly, a 26−2 fractional factorial design for screening several experimental variables (fiber-coating type, extraction temperature, extraction time, stirring rate, desorption temperature, and desorption time) was done. After, a two-factor central composite design for optimizing, the experimental conditions were carried out. The chosen experimental conditions were: fiber, PDMS/DVB; extraction time, 45 min; extraction temperature, 60 °C; desorption time, 3 min; desorption temperature, 260 °C, and stirring speed, 500 rpm. Using those conditions the limits of detection obtained for tetraconazole, myclobutanil, and diniconazole were in the order of few μg L−1 in grape and apple liquid extracts. Recoveries were from 93.6% to 112.1%. Relative standard deviation ranged from 1.2% to 11.6% (apple) and 6.7 to 18.0% (grape). The method was applied to five grape samples and 13 apple samples collected in Navarra, Rioja, and Basque Country. Quantification was performed by the standard addition method. Three standard additions by duplicate covering adequate range concentration were used. Myclobutanil was found in three apple samples (110–122 μg L−1) and diniconazole in one grape sample (9.4 μg L−1).

Biochip Technology for the Detection of Animal Species in Meat Products

Abstract: The verification of declared components in meat products is an essential task of food control agencies worldwide. To date, the ELISA and species-specific polymerase chain reaction (PCR) are two commonly applied analytical tools employed by many authorized food control laboratories. These trusted methods however do not allow the simultaneous detection of all the animal species present in a meat sample. Additionally, detection of undeclared components resulting from inadvertent contamination or deliberate adulteration of the meat products requires additional processing of the samples, resulting in increased expenditure. The use of DNA biochip analysis that allows simultaneous processing of many meat products, while concomitantly generating results for the detection of all animal species present in the meat products is thus highly desirable. In this work, two commercially available animal chip detection systems (CarnoCheck Test Kit and MEATspecies LCD Array) are compared in terms of sensitivity, robustness, reproducibility, and ease of handling. The two animal species differentiation biochip methods compared well in efficiency and could simultaneously detect from eight to 14 animal species in the meat products. Detection limits were found to be in the range of 0.1% to 0.5% in meat admixtures, with good reproducibility of results. More than 70 commercially available meat samples were analyzed in this work, with the results validated against traditional PCR methodology. Both biochip methods performed well and could be implemented for routine use in any food control agency.

Analytical Application of a Sample Process Control in Detection of Foodborne Viruses

Abstract: Sample process controls (SPCs) are an essential component of methods to detect viruses in food, as they verify that the sample treatment has operated correctly. Also, the use of an SPC can allow the efficiency of extraction of the target to be estimated for each individual sample analysed. The use of murine norovirus as SPC is here described. Its efficiency of extraction from different food products was 39.47%, 24.79% and 36.29% for strawberry, lettuce and shellfish samples. An incorrectly performed sample treatment was modelled to demonstrate the effectiveness of this control.

FTIR Spectroscopy and Direct Orthogonal Signal Correction Preprocessing Applied to Selected Phenolic Compounds in Red Wines

Abstract: The composition of phenolic compounds plays an important role in food science and nutrition; thus, there is a need of a new method of analysis that is able to speed up the monitoring of product quality parameters In this view, the amount of selected color components of 145 commercial red wines (total wine color, polymeric pigments, total anthocyanins, and copigmentation index) was investigated using Fourier transform mid-infrared spectroscopy (MIR) combined with partial least squares (PLS) regression The feasibility of several preprocessing algorithms (first and second derivative, standard normal variate, and direct orthogonal signal correction) was compared in terms of coefficient of determination (R2) and root mean square error of prediction using an independent test set of wines The composition of red wines showed great difference in terms of total color (507 ± 195 AU at 520 nm) compared to copigmentation index (066 ± 058 AU at 520 nm) The best prediction model was obtained using direct orthogonal signal correction (DOSC) preprocessing In particular, the prediction of total wine color, total anthocyanins, and polymeric pigments showed a good fitting (R2 ≥ 082), whereas copigmentation index was more difficult to be predicted by FTIR (R2 = 057) This preliminary study showed the potential of MIR spectroscopy with DOSC–PLS algorithm to successfully analyze selected color components of red wine on a large number of samples in short time with almost no sample preparation and no chemical waste is created

Novel Coulometric Approach to Evaluation of Total Free Polyphenols in Tea and Coffee Beverages in Presence of Milk Proteins

Abstract: Electrogenerated hexacyanoferrate(III) ions have been used as coulometric titrant for the determination of total free polyphenols in beverages. Stoichiometric coefficients of natural flavonoids (rutin, quercetin, and taxifolin) in their reaction with [Fe(CN)6]3− ions were established. The number of electrons involved in the oxidation corresponds to number of phenolic OH groups in the molecule of polyphenols. Proteins (casein and bovine serum albumin) bind polyphenols in the complexes that leads to significant decrease of free polyphenols portion (in the range of 5–76%). Ferric reducing power (FRP) of eight tea and 17 coffee samples was determined. The absolute FRP values ranged from 224 to 405 and from 241 to 488 C cup−1 for tea and coffee, respectively. Effect of milk proteins on total free polyphenols of tea and coffee and appropriate alteration of beverages FRP were evaluated. Milk addition decreases FRP of drinks in the range of 10–70% reflecting high content of inactive polyphenols.

Comparison of Various Preparation Methods for Determination of Organic Acids in Fruit Vinegars with a Simple Ion-Exclusion Liquid Chromatography

Abstract: An ion-exclusion liquid chromatography with mobile phase 0.005 mol L−1 H2SO4 and step flow rate gradient (0.2 mL min−1 in the first 40 min and 0.5 mL min−1 from 41 to 60 min) was used to determine 20 organic acids simultaneously at 17 °C within 51 min. The peak resolutions (Rs) were 0.45∼3.02 and separation factors (α) were all higher than 1. Impurities in fruit vinegar executed with direct injection or C18 cartridge clean-up for analysis would influence the glutaric and oxalic acid measurement; however, SAX cartridge extraction could reduce the interferences (organic acid recoveries were 93.93∼99.98%). Acetic, ascorbic, citric, malic, and malonic acids were the major organic acids in fruit vinegars (apple, apple sparkling, plum, cranberry, and grape).

Evaluation of Metal Concentrations in Red Tilapia ( Oreochromis spp ) from Three Sampling Sites in Jelebu, Malaysia Using Principal Component Analysis

Abstract: Concentration of V, Mn, Fe, Co, Cu, Zn, As, Se, Cd, and Pb in muscle, liver, and gill tissues of red tilapia (Oreochromis spp) sampled from three different aquaculture sites which include earthen pond, ex-tin mining pool, and concrete tank in Jelebu, Negeri Sembilan, were determined using microwave-assisted digestion–inductively coupled plasma-mass spectrometry. Accumulation patterns relating organs and elements, as well as origins and elements, were evaluated using multivariate statistics. With the aid of principal component analysis, it is possible to visualize the distribution pattern of metals in different organs as well as clustering tendencies of tilapia samples according to the production sites. In general, levels of V, Co, Fe, Cu, Zn, Se, and Cd in liver were higher than those in muscles and gills, whereas Mn and Pb were higher in gills while As in muscles. Results from principal component analysis revealed that there are similar pattern of metal distribution among organs regardless of the production sites. It is also suggested that Cu, As, and Pb are the best describers in characterizing the studied organs, where liver tissues are associated with high Cu, gills with high Pb, and muscles with high As. On the other hand, V, Co, and Pb are observed to be key discriminants for sample origins.

A Comparison between UV Spectrophotometer and High-performance Liquid Chromatography Method for the Analysis of Sodium Benzoate and Potassium Sorbate in Food Products

Abstract: Sorbic and benzoic acid and their salts have been widely used in the food industries for many years as important food preservatives in order to inhibit various bacteria, yeasts and fungi growth in acidic media (Qi et al. 2009). The purpose of this study is to determine the amount of the aforementioned preservatives in foods such as cookie and yogurt diluted with water and cucumber pickle. The content of these preservatives were simultaneously determined by UV spectrophotometer and high-performance liquid chromatography (HPLC) and their data for the number of some food samples have been compared. The results show that the HPLC method is more selective for determination of the potassium sorbate and sodium benzoate in such foods which have interference compounds in their products.

Substitution of Antibody with Molecularly Imprinted Film in Enzyme-Linked Immunosorbent Assay for Determination of Trace Ractopamine in Urine and Pork Samples

Abstract: A new direct competitive enzyme-linked immunosorbent assay (ELISA) with molecularly imprinted film as artificial antibody was developed to detect ractopamine (RAC) in urine and pork samples. The imprinted film was directly synthesized on the well surface of 96-well plate by an organic–inorganic hybrid technology and evaluated by fourier transform infrared (FT-IR), static, and kinetic adsorption experiments. The imprinted film exhibited an antibody-like binding ability and rapid adsorption speed. The established ELISA method gave a good sensitivity (IC50, 15.77 μg L−1) and a low detection limit (IC15, 0.01 μg L−1) for RAC under the optimum conditions, and it was applied to the determination of RAC in urine and pork samples spiked at three levels with recoveries ranging from 77.7% to 108.9% (urine) and from 93.5% to 101.1% (pork). The obtained results, which correlated well with those gained from the traditional high performance liquid chromatography (HPLC) method, demonstrated that the developed ELISA method was reliable for RAC determination in real samples.

Determination of Frying Quality of Vegetable Oils used for Preparing Falafel using Infrared Spectroscopy and Multivariate Calibration

Abstract: The frying qualities of palm and soybean oils are determined using infrared spectroscopy and multivariate calibration. Compare to soybean oil, palm oil is more resistive to the chemical and physical changes and this is attributed to the high degree of unsaturation of soybean oil (61.9%) compare to palm oil (13.8%). After 48 h in service, the oil samples were effectively clustered into two groups using principal component analysis which indicated that both oils still maintain their chemical identities. Partial least squares regression (PLS1 and PLS2) a long with mid-FTIR data are used for predicting free fatty acid, viscosity, and total polar compounds of the used oils without running expensive standard procedures. PLS1 and PLS2 outperformed PCR and MLR for predicting the quality indicators of the frying oils. For palm oil and at the optimum calibration conditions, the obtained accuracies (SD) are 105.6% (0.05), 99.8% (1.10), and 103.9% (0.16) for free fatty acid, viscosity, and total polar compounds, respectively. The proposed method is simple, less-expensive, and has comparable accuracy/precision with standard procedures that often used for monitoring frying oils.

Simultaneous Determination of 69 Pesticide Residues in Coffee by Gas Chromatography–Mass Spectrometry

Abstract: A method using gel permeation chromatography (GPC) combined with solid-phase extraction (SPE) cleanup followed by gas chromatography–mass spectrometry (GC-MS) has been established for quantitative determination of 69 pesticide residues in coffee Based on an appraisal of the characteristics of GC-MS, validation experiments were conducted for 69 pesticides In the method, 20 g samples were mixed with 5 ml water and 1 g sodium chloride and extracted with 5 ml of ethyl acetate by blender homogenization, centrifugation, and filtration Evaporation was conducted and the sample was injected into a 250 mm × 10 mm S-X3 GPC column, with ethyl acetate–n-hexane (1:2 v/v) as the mobile phase at a flow rate of 3 ml/min The 4–15 min fraction was collected for the SPE cleanup, which was Envi-Carb SPE cartridge coupled with NH2-LC SPE cartridge with acetone–ethyl acetate (2:5 v/v) as the eluted solvent The eluents were collected and then evaporated to dryness, which was redissolved in 05 ml ethyl acetate for GC-MS analysis For the 69 pesticides determined by GC-MS, the portions collected from GPC were concentrated to 05 ml and exchanged with 5 ml n-hexane In the linear range of each pesticide, the correlation coefficient was R2 ≥ 099 At the low, medium, and high fortification levels of 005–10 mg/kg, recoveries fell within 60–120% The relative standard deviation was between 13% and 223% for all 69 pesticides The limits of detection for the method were 10 μg/kg to 150 μg/kg, depending on each pesticide

Total Cholesterol and Desmosterol Contents in Raw, UHT, Infant Formula Powder and Human Milks Determined by a New Fast Micro-HPLC Method

Abstract: A simple, fast, sensitive, and environmental friendly micro-method is described for the determination of desmosterol and cholesterol in milk samples using isocratic normal phase high performance liquid chromatography and diode array detection. After sample micro-saponification, the chromatographic separation is achieved in 10 min, further reduced to 6 min when only cholesterol is expected to be present. The method is accurate, presenting cholesterol and desmosterol recoveries >96% and inter-day RSD lower than 3%. Quantification limits were clearly below the requirements for any milk sample, with 40 and 20 μg/100 mL for cholesterol and desmosterol, respectively. Several raw and UHT commercial milk samples, infant powder formulas, and human breast milks were analyzed, with cholesterol and desmosterol (present only in the latter) contents within reported amounts. The proposed method proved to be simple and feasible for determination of a large number of samples, requiring less solvent consumption (9–13 mL of hexane for all saponification/extraction/chromatographic steps) and simpler equipment than most ones reported, and a further possibility of partial solvent recycling due to the isocratic chromatographic mode.

On-Site NIR Spectroscopy to Control the Shelf Life of Pork Meat

Abstract: Control of meat shelf-life includes the time that it remains in the exhibitor of sale (such as the supermarket) until its rejection for the consumer, or withdrawal due to expiry date. Near infrared spectroscopy (NIRS) is one of the most promising techniques for large-scale meat quality control. This study investigated the potential of on-site NIRS portable instrumentation-based models to predict three microbiological parameters to establish if pork meat is acceptable or not for consumption (aerobic Mesophilous microorganisms, Enterobacteriaceae, and lactic acid bacteria) and pH to quality control food preservation and shelf-life extension on intact slices of pork meat packaged under two different modified atmospheres. NIR calibrations were developed by using an on-site Phazir instrument (Polychromix, Wilmington, MA, USA) in the range 1,600–2,400 nm. A total of 252 samples of pork meat slices were directly scanned twice in reflectance mode on trays, once before and another one after removing the film cover at 1, 3, 5, 7, 9, 12, and 15 days of storage. Results showed that spectra of meat acceptable or not for consumption have marked differences around 1,660 nm. NIRS quantitative prediction models showed r 2 values between 0.19 and 0.65 for the microbiological parameters assayed. The developed NIRS methodology makes possible on-site prediction of microbiological status of pork meat with a standard error of cross-validation around 1 log cfu/g. Results have shown that modified atmosphere packaging has no influence on calibration statistics.

Use of Multivariate Analysis Techniques for Evaluation of Analytical Data—Determination of the Mineral Composition of Cabbage (Brassica oleracea)

Abstract: Cabbage (Brassica oleracea) is a vegetable food that is found in red and white varieties, and it has been consumed worldwide as raw or cooked In this paper, the mineral composition of cabbage collected in 24 Brazilian cities was determined and the results were evaluated using multivariate analysis The samples were digested using nitric acid and hydrogen peroxide and were analyzed using inductively coupled plasma optical emission spectrometry The accuracy of the method was confirmed by analysis of a certified reference material of spinach leaves, furnished by National Institute of Standard and Technology The study involved 55 samples, being 31 of the white specie and 24 of the red specie The results expressed as milligrams of element per kilogram of sample demonstrated that the concentration ranges varied from 1,6029 to 4,0683 for potassium, 2175 to 7662 for phosphorous, 2219 to 7447 for calcium, 672 to 2860 for magnesium, 081 to 440 for manganese, 191 to 860 for iron, 001 to 024 for molybdenum, 117 to 510 for zinc, 272 to 5910 for sodium, and 035 to 579 for strontium The principal component analysis and hierarchical cluster analysis evidenced that the mineral composition of the red specie is not different of the white specie

Simple Method for Measuring the Peroxide Value in a Colored Lipid

Abstract: We developed a simple method for quantification of the peroxide value (PV) in colored lipids on the basis of the reaction between triphenylphosphine (TPP) and oxidized oil to afford triphenylphosphineoxide (TPPO) Diphenylphosphineoxide (DPPO) was employed as internal standard The formed TPPO was analyzed by high-pressure liquid chromatography–UV spectroscopy with absorption at 260 nm The conditions that gave the highest correlative calibration curve between the peak area on the chromatogram and peroxide value were identified: the optimum TPP–oxidized oil mix ratio, reaction temperature, and reaction time were found to be 2:1, 40 °C, and 30 min, respectively Linear calibration curves, passing through the origin, were obtained for PV versus TPPO and TPPO versus DPPO The quantification limit for this method was 201 pmol hydroperoxyl group, which corresponds to a PV value of 02 meq/kg in a 10-mg oil sample This method was used to measure the PV in colored fats and oils or lipids extracted from dark meat and processed food containing a coloring agent Though the official method could not measure the PVs in the colored lipids, the method proposed here, which uses an inexpensive chemical reagent and machine, could The developed method could play an important role for food quality control

Quantification of Nitrite/Nitrate in Food Stuff Samples Using 2-Aminobenzoic Acid as a New Amine in Diazocoupling Reaction

Abstract: 2-Aminobenzoic acid has been used as an amine in diazocoupling reaction to form an azo dye in the quantification of nitrite/nitrate at trace level. The formed azo dye has an absorption maximum at 550 nm in aqueous phase, and the resulted dye can be extracted into organic solvent to lower the detection limit. The method obeys Beer's law in the concentration range 0–10 µg of nitrite in 25 ml of aqueous solution with a molar absorptivity of 3.6 × 103 L mol−1 cm−1 and 0–2 µg of nitrite in 5 ml of organic phase. The detection limit of the dye has been found to be 0.056 μg ml−1. Nitrate is determined by reducing it to nitrite after passing through a copperized cadmium reductor column. The effect of interfering ions on the determination of nitrite/nitrate has been described. The developed method has been applied to determine the nitrite/nitrate trace level in vegetable, fruit juice, and milk powder samples.

Determination of Rosmarinic Acid by High-Performance Liquid Chromatography and Its Application to Certain Salvia Species and Rosemary

Abstract: This study describes a method development for the determination of rosmarinic acid (RA) by using a gradient high-performance liquid chromatography (HPLC) and its application to certain plant materials. The analysis was performed by utilizing a two solvents system [A: methanol/water/formic acid (10:88:2; v:v:v); B: methanol/water/formic acid (90:8:2; v:v:v)] on a reverse-phase column. The flow rate and injection volume were 1 ml min−1 and 10 μl, respectively. Signals were detected at 280 nm. In addition, an internal standard (IS) technique was applied for the analysis of RA to increase precision, and propylparaben was employed for this purpose. The repeatability results as RSD% were 1.66, 1.17 and 1.26 for intra-day and 1.38 was for inter-day with the employment of (3.67 × 10−5 M) RA. A limit of linearity (LOL) was observed in a wide (1.13 × 10−5–5.65 × 10−4 M) concentration range. Linearity parameters were also examined in the range of 5.95 × 10−6–7.14 × 10−5 M RA, and very good correlation was observed. The limit of detection (LOD) and limit of quantification (LOQ) (for inter-day) were 1.60 × 10−6 M (signal/noise [S/N] = 3.3) and 4.80 × 10−6 M (S/N = 10), respectively. The method was applied to the extracts of certain Lamiaceae plants (Salvia candidissima Vahl. subsp. candidissima, S. sclarea L., S. verticillata L. subsp. verticillata and R. officinalis L.), and reasonable results were obtained.

Rapid and High-Throughput Determination of Melamine in Milk Products and Eggs by Full Automatic On-line Polymer Monolith Microextraction Coupled to High-Performance Liquid Chromatography

Abstract: A rapid and high-throughput method for monitoring melamine (MEL) in milk products and eggs was presented. This method was based on a full automatic platform that was composed of on-line polymer monolith microextraction and high-performance liquid chromatography with ultraviolet detection. A poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-ethylene dimethacrylate) monolith was selected as the sorbent for purification and enrichment of MEL in milk products and eggs. A novel mixed-mode chromatographic column packed with octyl and sulfonic acid co-bonded silica was employed for quantitative determination of MEL in real samples. Several factors affecting extraction performance were investigated. Under the optimal conditions, the recoveries of MEL in milk products and eggs spiked at three levels of 0.5, 5.0, and 20.0 mg/Kg, ranged from 87.0% to 95.5%, with RSDs less than 6.4%. The limits of detection were 0.024 and 0.018 mg/Kg for MEL in the milk products and eggs, respectively.

Hydrophilic Interaction Chromatography (HILIC) in the Analysis of Relevant Quality and Safety Biochemical Compounds in Meat, Poultry and Processed Meats

Abstract: HPLC methods based on hydrophilic interaction chromatography (HILIC) have been recently applied to the analysis of biochemical compounds, related to the quality, in meat and poultry as well as meat products like cooked ham and dry-cured ham. This type of chromatography has also been successfully used for the analysis of antibiotic residues in meat and poultry. HILIC chromatography has an increasing relevance for the analysis of polar compounds in foods due to its good retention without need for derivatisation. In general, HILIC-based methods have shown good performance for the analysis of polar biochemical compounds like dipeptides, creatine and creatinine, nucleotides and nucleosides, sphingolipids and residues, mainly antibiotics, in rather complex matrices such as muscles. Thus, this manuscript presents a review of recent applications of HILIC methods for the analysis of quality-related biochemical compounds and residues in meat, poultry and processed meats.

Quantification of Triacylglycerols in Olive Oils Using HPLC-CAD

Abstract: This paper describes a reversed phase high-performance liquid chromatography method for the quantification of triacylglycerol (TAG) compositional profile in olive oils. The chromatographic separation was achieved using a C18 column, and the detection was accomplished using a charged aerosol detector. TAG peaks were identified using retention times and by addition of TAG standards. The linearity, matrix effect, and accuracy (precision and trueness) were validated; detection and quantification limits of the method were estimated. The developed analytical method was applied to the determination of the TAG composition and the estimation of the concentration of each individual TAG, using an internal quantification standard (tristearin). From the TAG compositional profile, a fatty acid compositional profile could be calculated. The proposed method appears to be rapid and simple to determine TAGs in olive oil.