Background: Monitoring the acidity of cheese is an important control mechanism in various stages of manufacture, including aging. Acid development in cheesemaking is essential to cheese flavor, texture, and safety. Objective: The aim of the work was to develop and validate calibration models by using NIR spectroscopy, which allows for the monitoring of changes in cheese acidity (pH and titration acidity) during cheese ripening. Methods: Cheeses were analyzed by an FT-NIR spectrometer. Each of the samples was analyzed three times, and for calibration, an average spectrum was used. A partial least-squares regression was used to develop calibration models. The constructed calibration models were validating by full cross-validation. Results: Calibration models were created with a high correlation coefficient for the following cheese pH levels: blue cheese (0.966), Olomouc curd read smear cheese (0.984), and fresh goat cheese (0.980). Results of the calibration of titratable acidity are functional for fresh goat cheese (0.953) and mozzarella (0.999). Conclusions: The results of these new calibration methods showed the possibility of NIR technology for the fast determination of pH and titratable acidity. Highlights: Detection of cheese acidity using FT-NIR spectrometry enables rapid evaluation of the process of lactic acidification in particular cheese technological operations, including the maturing of cheeses.
This paper describes a single-laboratory validation of a liquid chromatography-diode array detection (LC-DAD) method for quantification of 12 major cannabinoids in Cannabis dried plant materials, concentrates, and oils. The method met Standard Method Performance Requirements for quantitative analysis of cannabinoids in Cannabis concentrates and Cannabis dried plant materials. The LOQs were in the range 0.003-0.10% (w/w), depending on the analyte and matrix. Spike recoveries were between 96.7 and 101.3% with relative SDs (RSDs) ≤2.3%. Precision expressed as repeatability and intermediate precision was within 0.3-4.8 and 1.1-5.1%, respectively. The chromatographic separation conditions used in this versatile method are compatible with both DAD-UV and MS detection. During method validation, high-resolution quadrupole time-of-flight MS was employed as a secondary detector (connected in series to the LC-DAD instrument) to provide high confidence identification of target analytes and as a tool for monitoring other cannabinoids for which reference standards were not available. The obtained results demonstrate applicability of the method to quantitative analysis of important cannabinoids in dried plants, concentrates, and oils. Limited data were generated for a food matrix (Cannabis-containing cookies) using this method with LC coupled to a compact single quadrupole mass spectrometer.
This study monitored the influence of milk samples temperature on the measuring accuracy of FT-NIR spectroscopy in milk content analysis. Reference methods were used to determine dry matter, fat, protein, and lactose content in cow's milk. Milk samples were measured in reflectance mode on an integrating sphere with the use of a compression cuvette and a transflectance cuvette, ensuring a beam trajectory length of h = 0.2 mm. The samples were measured at 18, 20, 22, 24, and 40°C, and analyses were performed at 100 scans at a resolution of 8 cm-1. The measurements were influenced by the temperatures of the samples during the evaluation of all analyzed constituents (P < 0.05). Our results confirmed that the accurate determination of milk constituents requires maintaining, during analysis, the temperature conditions of the samples and the conditions for which the spectrophotometer calibration was designed.
Several mineralization methods for the determination of selenium using hydride generation optical emission spectrometry with inductively coupled plasma in biological samples (whole egg powder and pork liver) were compared using the analysis of means (ANOM) method. This statistical tool is suitable for graphical representation of testing on simple comparative experiments. The results yielded by ANOM are identical with those obtained with the commonly used analysis of variance (ANOVA) method; however, the graphical output of ANOM is more illustrative in comparison to ANOVA. Both methods indicated a significant discrepancy between the results obtained using muffle furnace ashing mineralization and the results provided by other mineralization methods. This is probably due to the loss of volatile selenium compounds during the decomposition of organic matter.
The study examined the effect of the choice of reference method on the functionality and reliability of calibrations in near-IR (NIR) spectroscopy intended for measuring the fat content in raw cow's milk. The fat content in the milk samples was evaluated using methods according to either Röse-Gottlieb or Gerber. The same samples were then subjected to analysis on an Antaris FT-NIR spectrometer. Using a partial least-squares algorithm, calibration models were created for both methods from the values measured. The calibration models show very good values of standard error of calibration: 0.133 for the Gerber method and 0.095 for the Röse-Gottlieb method. These calibrations were subsequently used to analyze 30 new samples of cow's milk of undefined fat content, and the differences in the values were evaluated using statistical paired t-test to a median value at a probability level of α = 0.05. No statistically significant differences were found. It was revealed that the reference method used for calibrating the device evaluating the fat content in raw cow's milk has no effect on the functionality and reliability of the calibration model.
This study investigated the ability of two methods to detect adulteration of goat cheeses via the addition of cow's milk, with a negligible effect on the raw materials. Cheeses were produced from a mixture of goat's and cow's milk and were then analyzed by Fourier transform near-IR (FT-NIR) spectroscopy and competitive ELISA. The cheese spectra were scanned in the spectroscope in reflectance mode on an integrating sphere at 80 scans and a resolution of 4 cm(-1). The spectra were evaluated via discriminant analysis, and a calibration was created via a partial least-squares algorithm to quantify the cow's milk admixture. A correlation coefficient of R = 0.999 was reached with a standard error of calibration of 0.0407. The results were statistically processed to a median value via a t-test. Adulteration detection by the ELISA method was performed using a commercial Milk Fraud/Bovine ELISA kit. It was found that the FT-NIR spectroscopy method is capable of detecting an admixture of cow's milk in goat cheese as small as 1%. The ELISA method did not return satisfactory results for the detection of adulteration with cow's milk.
A collaborative study in 10 laboratories was performed to validate an ELISA method developed for the quantitative determination of peanut protein in foods. The ELISA kit used for this study is based on rabbit polyclonal antibody. This kit does not produce any false-positive results or cross-reactivity with a broad range of peanut-free food matrixes. All participants obtained the peanut ELISA kit with standard operational procedures, a list of samples, the samples, and a protocol for recording test results. The study included 15 food samples. Three food matrix samples of zero peanut content showed peanut protein content lower than the first standard (0.10 mg/kg). Three samples with peanut declared as an ingredient revealed peanut protein content outside the calibration curve (absorbance was above the highest standard) in all laboratories, and three samples had the peanut content reported either above the highest standard or within the calibration curve, depending on the laboratory. Six samples with peanut declared as an ingredient gave the peanut protein content within the calibration curve. Only these six samples, together with a positive control sample (CS2), were used for statistical evaluation. The statistical tests (Cochran, Grubbs, and Mandel) and analysis of variance were used for the evaluation of the collaborative study results. Repeatability and reproducibility limits, as well as an LOQ (LOQcollaborative 0.22 mg peanut proteins/kg) and an LOD (LODcollaborative 0.07 mg peanut proteinslkg) for the kit were calculated.
A rapid HPLC method for the analytical resolution of cinacalcet enantiomers was developed. Four chiral columns (two amylose and two cellulose type) were evaluated in RP systems. Excellent enantioseparation with a resolution of more than 6 was achieved on Chiralpak AY (amylose 5-chloro-2-methylphenylcarbamate chiral stationary phase) using 10 mM triethylamine (pH 8.0)-acetonitrile (40 + 60, v/v) mobile phase. Validation of the HPLC method, including linearity, LOD, LOQ, precision, accuracy, and selectivity, was performed according to the International Conference on Harmonization guidelines. The method was successfully applied for the determination of (S)-cinacalcet in enantiopure active pharmaceutical ingredient (R)-cinacalcet.
- MeSH
- algoritmy MeSH
- alkoholy MeSH
- indikátory a reagencie MeSH
- koncentrace vodíkových iontů MeSH
- limita detekce MeSH
- naftaleny chemie MeSH
- polysacharidy chemie MeSH
- pufry MeSH
- referenční standardy MeSH
- reprodukovatelnost výsledků MeSH
- rozpouštědla MeSH
- stereoizomerie MeSH
- teplota MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- Publikační typ
- časopisecké články MeSH
An interlaboratory study in 12 laboratories was performed to prove the validation of the ELISA method developed for the quantitative determination of mustard protein in foods. The ELISA kit used for this study is based on rabbit polyclonal antibody. This kit did not produce any false-positive results or cross-reactivity with in-house validation for a broad range of food matrixes with no detectable mustard protein. All participants obtained the Mustard ELISA kit with standard operational procedures, a list of samples, samples, and a protocol for recording test results. The study included 15 food samples and two spiked samples. Seven food matrix samples of zero mustard content and four samples with mustard declared as an ingredient showed mustard protein content lower than that of the first standard (0.42 mg/kg). Four samples with mustard declared as an ingredient revealed mustard protein content above 12.5 mg/kg (the highest standard). The statistical tests (Cochran, Dixon, and Mandel) and analysis of variance were used to evaluate the interlaboratory study results. Repeatability and reproducibility limits, as well as an LOQ (1.8 mg mustard proteins/kg) and LOD (0.5 mg mustard proteins/kg), for the kit were calculated.
An interlaboratory study was performed in eight laboratories to validate an ELISA method developed for quantitative determination of casein in foods. The ELISA kit used is based on rabbit polyclonal antibodies. The kit is quite specific; no false-positive results or cross-reactivities were obtained for a broad range of food matrixes with zero content of milk proteins. All participants in the study received the casein kit, which included a standard operating procedure, a list of the samples, the samples, and a protocol for recording test results. The study included nine food samples: wheat flour, buckwheat flour, instant potato purée with milk, instant coffee with sugar and cream, a mixture for fancy bread, salami, liver paté, chocolate muesli with nuts, and a mixture for gluten-free bread. Three food samples with zero content of milk proteins showed a casein content lower than the lowest casein standard (1.0 mg CAS/kg) in most laboratories and measurements (64%). In 98% of the cases, the casein content was lower than the estimated LOQ. Two food samples with no dairy ingredient declared on the ingredient list contained casein levels higher than the second casein standard (3.0 mg CAS/kg) and the third standard (10.0 mg CAS/kg), respectively. Four food samples containing milk as an ingredient tested positive, and three showed casein contents higher than the highest standard (30.0 mg CAS/kg). The statistical tests (Cochran, Dixon) and analysis of variance were used for evaluation of the interlaboratory study results. Repeatability and reproducibility limits as well as LOQ (1.8 mg CAS/kg) and LOD (0.5 mg CAS/kg) for the kit were calculated from the results of the interlaboratory study.
- MeSH
- alergeny analýza MeSH
- analýza potravin metody MeSH
- ELISA metody MeSH
- kalibrace MeSH
- kaseiny analýza MeSH
- králíci MeSH
- mléčné bílkoviny chemie MeSH
- mléčné výrobky analýza MeSH
- potraviny MeSH
- referenční standardy MeSH
- reprodukovatelnost výsledků MeSH
- zkřížené reakce MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
