Food Analytical Methods最新文献

The necessity of identifying and quantifying sugars in food processing is endless for maintaining food quality attributes such as color, taste, texture, monitoring regulatory compliance, labeling packages, and maintaining authenticity. Despite available analytical methods for characterizing sugar molecules, the limitations of conventional methods drive researchers to seek more convenient alternatives. This study aimed to characterize common disaccharides such as sucrose, lactose, maltose, and trehalose using a time domain nuclear magnetic resonance (TD-NMR), facilitating a quick, cost-effective, and user-friendly approach. In this experiment, transverse relaxation distribution curve was analyzed for characterizing disaccharides. Two peaks, referred to as the main and secondary peak(s), were observed for all the disaccharides, while a single peak (the main peak) was observed for pure water. Although they have similar molecular formulas and weights, lactose exhibited the longest relaxation time for the secondary peak, followed by trehalose, sucrose, and maltose. This behavior was assumed due to the interaction of sugar molecules with water. The increasing concentration of disaccharide in the solution displayed the leftward shifting of peaks. Maltose showed two secondary peaks, which were not observed in other sugar samples. The NMR showed potential to distinguish disaccharides from unknown powders and solutions by analyzing either the relaxation time of the secondary peak or the ratio of the secondary to the total peak. Moreover, quantification is possible from the standard curves of relaxation time and the combined peak area of the main and secondary peaks with the corresponding sugar concentration. However, it shows challenges in discrimination between α- and β-isomers.

Olive oil, one of the foods that has a wide place in production and consumption worldwide, is considered important in terms of taste and health, thanks to the components it contains. However, incorrect approaches to storing this seasonally produced food cause significant losses for many consumers. In this study, by simulating a general consumer behavior, three extra virgin olive oils (EVOO) produced annually were procured and stored under different conditions for 6 months; and the effects of time, temperature, and light parameters were examined. The phytochemical properties of olive oils were analyzed and repeated after 3 and 6 months. During the process, negative changes occurred in free fatty acid values from 0.51 ± 0.01 to 2.04 ± 0.01 (oleic acid%), total phenolic content amounts from 481.77 ± 3.24 to 96.02 ± 0.94 (mg GAE/kg oil), total antioxidant capacity from 215.93 ± 1.67 to 11.21 ± 0.17 (mg TE/kg oil), and peroxide values from 13.58 ± 0.34 to 31.96 ± 0.85 (meq O₂/kg). Oleic acid ratios were between 66.37 ± 1.09% (Halhalı) and 72.97 ± 1.19% (Memecik) in all processes and samples. No defect was detected in sensory test results for up to 6 months. Among the most important phenolic components, hydroxytyrosol (max 33.18 ± 0.81 mg/kg) and tyrosol (max 3.93 ± 0.03 mg/kg) showed a fluctuating change, and oleuropein (max 7.40 ± 0.12 mg/kg) tended to decrease. Statistical results performed with all samples and parameters using principal component analysis showed that oleic acid, linoleic acid, hydroxytyrosol, total unsaturated fatty acid values, some terpenes, and C6 volatile components were the most characteristic components for the oils studied. Additionally, the results showed that time was more effective than temperature and light variables in storage.

Mango aroma and flavor are attributed to hundreds of volatile metabolites and their combinations, concentrations, and proportions, which give the fruits unique aromatic characteristics. This study evaluated the sensory characteristics and volatile organic compounds (VOCs) in five dried mango varieties. The five dried mango types differed in VOC content and sensory characteristics. Dried Malika and Van Dyke mangoes were the most accepted by consumers, and CPAC 165/93 was the least accepted. The attributes “too weak” aroma and flavor, “not sweet enough,” and “hard texture” negatively influenced the product’s acceptance scores. A total of 149 volatile compounds were identified, with the highest levels belonging to the class of terpenes, aldehydes, and esters, and the following compounds were found at higher percentages: lactones in the Malika mango; acids, monoterpenes, and sesquiterpenes in the Van Dyke variety; esters and ketones in CPAC 165/93; alcohols in Amrapali; and aldehydes in Palmer. Principal component analysis (PCA) showed that the presence of compounds of the lactone and terpene classes positively influence the acceptance of the aroma and flavor of the dried mangoes, and the compounds of the ester and ketone classes contribute to the lower sensory acceptance of these attributes. Dried mangoes produced with the Malika and Van Dyke varieties were the most accepted by consumers; therefore, these varieties can be recommended for the food dehydration industry.

The consumption of dietary supplements has grown exponentially over the last few years, among which the oil obtained from evening primrose seeds stands out for containing a high level of polyunsaturated fatty acids, especially γ-linolenic fatty acid, which helps to reduce effects of menopause, premenstrual tension, and among other benefits. This work presents a study of the lipid quality of the eight main brands of evening primrose oil capsules on the national market, evaluated using ¹H nuclear magnetic resonance spectroscopy together with chemometric analysis techniques (principal component analysis and multiple linear regression). Therefore, among the commercially acquired samples, only two had a lipid profile close to the reference evening primrose oil, the others had scores ranging from 17.9 to 25.8, making them unsuitable for consumption. This was possible based on the identification of markers in the ¹H spectra with potential for study and application in determining the lipid quality of other encapsulated vegetable oils.

The aim of the present study was to investigate the feasibility and applicability of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (FT-IR-ATR) techniques, without extraction, with prior extraction of fat and after hydrolysis and methylation, to fatty acid methyl esters (FAME) to evaluate the content of trans fatty acids (TFA) in filled biscuits and to compare the results obtained with those obtained when elaidic acid was determined by the GC–MS technique. Eight commercial brands of chocolate filled biscuits and one package of hydrogenated vegetable fat were selected to be used as secondary standards by FT-IR-ATR. The presence of TFA was identified by FT-IR-ATR by visualization of the band at 966 cm⁻¹. No significant differences were found between the concentrations of TFA determined by the three methods tested. The study indicated that the FT-IR-ATR technique, when used to analyze the lipid extract and the samples in the form of FAME, is suitable for estimating the TFA content in chocolate filled biscuits.

This paper describes a unique method for quickly, accurately, and non-destructively determining the freshness of meat. During the spoilage of meat, CO₂ is evolved primarily through microbial respiration. The production of CO₂ is often a sign of active spoilage, which helps in determining the freshness and safety of meat consumption. The level of carbon dioxide evolved during meat spoilage was measured using a fluorescent material–coated capillary tube. A CO₂ sensing dye was immobilized in a hybrid sol–gel silica matrix followed by its deposition inside a glass capillary tube, which acts as the sensing medium. When the sensing medium is excited by a light source, it fluoresces. The intensity of the fluorescence emitted when meat samples are exposed to the capillary tube diminishes proportionally to the CO₂ concentration, thereby enabling quantification. The fluorescence intensity and CO₂ concentration were found to have a high linear correlation (R² > 0.95), demonstrating the method’s accuracy and dependability. A low response time of 12 s signifies the fast detection of changes happening in the evolution of CO₂ from meat. The recovery time is determined to be 17 s. Within this time, the sensor becomes ready to react to fresh stimuli for CO₂ detection. A short recovery time allows for more rapid successive measurements. This approach is environment-friendly and makes real-time measurements possible, making it ideal for on-site and in-line applications in the food sector. It provides the meat processing industry with an easy, affordable, and effective replacement for traditional methods, enabling quicker decision-making and quality control.

Vitamin D is a crucial nutrient, and its accurate quantification in food matrices, such as meat and egg, is vital for nutritional and health assessments. In the present study, two extraction methods, i.e., solid phase extraction (SPE) and dispersive liquid–liquid microextraction (DLLME), after sample hydrolysis by saponification, were compared for better vitamin D extraction from the samples. The extracted analyte was analyzed using liquid chromatography-tandem mass spectrometry (LC–MS/MS) by electron spray ionization method. The efficiency of the SPE method was tested with petroleum ether, chloroform, n-heptane, and dichloromethane solvents through C-18 Oasis cartridge, while the DLLME method was evaluated with varying combinations of extraction solvents (toluene, carbon tetrachloride, chloroform, and dichloromethane) and dispersive solvents (acetone, acetonitrile, and ethanol). The results showed that the recovery of the vitamin in the SPE method ranged between 8.6 and 17.2%, with the maximum recovery achieved using petroleum ether. On the other hand, the DLLME method yielded a broader range of recovery (2.4–118.9%) for the different combinations of dispersive and extraction solvents. As the maximum recovery was obtained for the combination of toluene and acetone in DLLME method, this was selected for further studies to extract vitamin D3 from boiled egg, cooked fish, and ready-to-eat food products (chicken biryani, chicken pulav, chicken soup, chicken curry, and chicken kurma). The vitamin D3 content in the food products varied in the range of 11.6–136.4 µg/kg, where boiled egg (11.6 ± 8.7 µg/kg) and fish (136.4 ± 8.8 µg/kg) had minimum and maximum quantities, respectively.

Graphical Abstract

Cresol isomers are compounds known as environmental chemical contaminants, and they are widely distributed in smoked foods. Thus, the objective of this study was to develop a method based on solid–liquid extraction with low-temperature purification (SLE-LTP) and analysis by gas chromatography-mass spectrometry (GC–MS) for quantification of three cresol isomers (o-cresol, m-cresol, and p-cresol) in smoked bacon samples. The SLE-LTP was optimized, validated, and compared with the QuEChERS method. The proposed method was selective after derivatization with BSTFA [N,O-Bis(trimethylsilyl)trifluoroacetamide], which achieved a limit of quantification of 53.3 μg kg⁻¹, recoveries between 90 and 116%, relative standard deviation lower than 13%, negative matrix effects, and linearity in the range of 53.3 to 1332.5 μg kg⁻¹ with coefficient of determination higher than 0.99 in matrix-matched calibration. The method was applied to quantify cresol isomers in five commercial samples of smoked bacon and the results showed concentrations between 62.1 and 1204 μg kg⁻¹. Finally, the developed methodology is suitable for monitoring cresol isomers, which are present in high levels in smoked bacon.

In the realm of food safety, the accumulation and potential health risks posed by persistent residues of broad-spectrum antimicrobials, which degrade slowly in the environment, have prompted the urgent development of efficient and sensitive detection methods. Addressing this challenge, nitrogen-doped carbon quantum dots (N-CQDs) were synthesized through a high-temperature hydrothermal method using citric acid and urea as sources. Utilizing these N-CQDs, a sensor incorporating molecularly imprinted polymers was developed through a sol–gel process with sulfadiazine (SDZ) as the template molecule. This involved using 3-aminopropyltriethoxysilane and tetraethyl orthosilicate as the monomer and cross-linker, respectively. The resulting sensor exhibited a linear detection range of 0 to 30 µmol/L and a notably low detection limit of 0.04 µmol/L. Further testing on actual pork samples revealed recovery rates between 95.10 and 108.30% and a relative standard deviation below 2.0%, emphasizing its high sensitivity and selectivity. This advancement not only enhances SDZ detection capabilities, but also paves the way for broader applications in food safety monitoring, setting a solid foundation for future developments in sensor technology.

Graphical Abstract

Freezing is a common method to maintain pork quality. However, prolonged frozen storage can cause oxidation reactions of metmyoglobin in pork, resulting in meat quality deterioration. Therefore, it is significant to detect frozen pork quality rapidly and non-destructively for public health and food safety. Metmyoglobin content is considered a critical indicator for evaluating the quality of frozen pork. In this paper, a rapid non-destructive method combining visible and near-infrared (VIS–NIR) spectroscopy technology with chemometrics was applied for the high accuracy ion of metmyoglobin content. First, VIS–NIR spectral data were collected on the pork samples with different freezing times. The raw spectral data were pre-processed using six methods: 1st derivative, 2nd derivative, Savitzky-Golay convolutional smoothing, vector normalization, standard normal variate, and multiple scattering corrections. Then, partial least squares (PLS) and random forest (RF) algorithms were applied to establish the prediction models of metmyoglobin content respectively, while the characteristic wavelengths were extracted by combining with the successive projections algorithm (SPA). The results showed significant effects on the prediction accuracy by using different modeling combinations. The MSC-RF-SPA model performed best in prediction, with a coefficient of determination (R²) of 0.901 and a root mean square error (RMSE) of 0.0216, which confirmed the ability to evaluate metmyoglobin content in frozen pork with high accuracy. The results of this study indicated that Vis–NIR spectroscopy technology coupled with MSC-RF-SPA modeling is a promising method, which provided a new way to accurately detect metmyoglobin content in frozen pork.