Prediction of peroxide value in omega-3 rich microalgae oil by ATR-FTIR spectroscopy combined with chemometrics

The influence mechanism of phospholipids structure and composition changes caused by oxidation on the formation of flavor substances in sturgeon caviar

The oxidation-induced phospholipids (PLs) underwent structural and compositional analysis, alongside the establishment of a simulation system to verify the link between phospholipid oxidation and flavor substances formation in sturgeon caviar. Structural alterations of PLs were tracked using 31P and 1H nuclear magnetic resonance (NMR), electron spin resonance spectroscopy (ESR), and Raman spectroscopy. The findings revealed a reduction in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) from 82.3% and 10.4% to 58.2% and 5.8% respectively. Free radical signals exhibited an initial increase followed by a decrease. The diminished intensity in Raman spectra at 970 and 1080 cm-1 indicated reduced fat unsaturation attributable to PLs oxidation. Correlation analysis highlighted a significant association between PC and PE containing C22:6, C20:5, C20:4, and C18:2 with flavor substances, suggesting their role as key precursors for flavor development. This study established a theoretical basis for understanding the change of flavor quality in sturgeon caviar during storage.

Impact of high-pressure processing on hemolymph, color, lipid globular structure and oxidation of the edible portion of blood clams

Impact of high-pressure processing (HP-P) on hemolymph and lipid globular structures of the edible portion (EP) of blood clams (BC) was investigated. HP-P above 400 MPa decreased heme iron content, while upsurged non-heme iron content. Increasing pressure induced gaps and abnormal hemocyte cell arrangements. However, HP-P at 300 MPa improved and maintained total hemocyte counts, the heme iron content, and a*-value in BC-EP. For lipid globular structures, the mean diameter drastically decreased when an HP-P pressure of 600 MPa was employed. HP-P at higher pressure induced lipid oxidation, along with decreases in monounsaturated and polyunsaturated fatty acids as well as increases in thiobarbituric acid reactive substances and peroxide value. FTIR spectra displayed a reduction in phosphate groups and cis double bonds in lipids from HP-P treated BC, compared to controls. Therefore, HP-P at 300 MPa is recommended for preparing ready-to-cook BC with less tissue damage and lipid oxidation.

Comparison of Alginate Mixtures as Wall Materials of Schizochytrium Oil Microcapsules Formed by Coaxial Electrospray

This work evaluated maltodextrin/alginate and β-glucan/alginate mixtures in the food industry as wall materials for the microencapsulation of Schizochytrium sp. oil, an important source of the omega-3 fatty acid DHA (docosahexaenoic acid). Results showed that both mixtures display a shear-thinning behavior, although the viscosity is higher in β-glucan/alginate mixtures than in maltodextrin/alginate. Scanning electron microscopy was used to assess the morphology of the microcapsules, which appeared more homogeneous for maltodextrin/alginate. In addition, oil-encapsulation efficiency was higher in maltodextrin/alginate mixtures (90%) than in β-glucan/alginate mixtures (80%). Finally, evaluating the microcapsules' stability by FTIR when exposed to high temperature (80 °C) showed that maltodextrin/alginate microcapsules were not degraded contrary to the β-glucan/alginate microcapsules. Thus, although high oil-encapsulation efficiency was obtained with both mixtures, the microcapsules' morphology and prolonged stability suggest that maltodextrin/alginate is a suitable wall material for microencapsulation of Schizochytrium sp. oil.

Screening of Spirulina strains for high copper adsorption capacity through Fourier transform infrared spectroscopy

Microalgae have emerged as promising biosorbents for the removal of toxic metals from industrial effluents due to the presence of various free functional groups. While the constitutes are distinct among different algal strains, it needs to screen the algae with high adsorption capacities for heavy metal ions by analyzing the algal components. In this study, a rapid and nondestructive Fourier transform infrared (FTIR) method combined PCA algorithm was used to discriminate algal strains according to their cellular components. With FTIR spectroscopy, we have found that the algal strains for high copper adsorption capacity (RH44, XS58, AH53, and RZ22) can be well differentiated from other strains via assessing the components involved in the biosorption of copper ions at the spectral window range of 1,200–900 cm⁻¹ mainly attributed to polysaccharides. Correspondingly, the copper removal efficiency by different Spirulina strains was also measured by biochemical assay and scanning electron microscopy (SEM) in order to confirm the screening result. Compared with the chemical measurement, the assessment based on spectral features appears fairly good in the evaluation and differentiation of copper adsorption capacity in various Spirulina strains. This study illustrates that FTIR spectroscopy may serve as a fast and effective tool to investigate the functional groups for copper ions binding in the Spirulina cell and it even offers a useful and accurate new approach to rapidly assess potential adsorbents for the high capacity of copper adsorption.

Mechanism, indexes, methods, challenges, and perspectives of edible oil oxidation analysis

Edible oils are indispensable food components, because they are used for cooking or frying. However, during processing, transport, storage, and consumption, edible oils are susceptible to oxidation, during which various primary and secondary oxidative products are generated. These products may reduce the nutritional value and safety of edible oils and even harm human health. Therefore, analyzing the oxidation of edible oil is essential to ensure the quality and safety of oil. Oxidation is a complex process with various oxidative products, and the content of these products can be evaluated by corresponding indexes. According to the structure and properties of the oxidative products, analytical methods have been employed to quantify these products to analyze the oxidation of oil. Combined with proper chemometric analytical methods, qualitative identification has been performed to discriminate oxidized and nonoxidized oils. Oxidative products are complex and diverse. Thus, proper indexes and analytical methods should be selected depending on specific research objectives. Expanding the mechanism of the correspondence between oxidative products and analytical methods is crucial. The underlying mechanism, conventional indexes, and applications of analytical methods are summarized in this review. The challenges and perspectives for future applications of several methods in determining oxidation are also discussed. This review may serve as a reference in the selection, establishment, and improvement of methods for analyzing the oxidation of edible oil. HighlightsThe mechanism of edible oil oxidation analysis was elaborated.Conventional oxidation indexes and their limited values were discussed.Analytical methods for the determination of oxidative products and qualitative identification of oxidized and non-oxidized oils were reviewed.

Analytical methods for determining the peroxide value of edible oils: A mini-review

Edible oils are prone to oxidation during processing and storage that may negatively affect the oil quality and human health. Determining the peroxide value (PV) of edible oils is essential because PV is one of the most typically used quality parameters to monitor lipid oxidation and control oil quality. Many approaches have been developed to determine the PV of oils. Among them, iodometric titration is the commonly used method for PV determination. Considering the limitations related to titrimetric methods, such as time and environmental concerns, several instrumental techniques have been considered as reliable alternatives. The advantages and limitations of classical titration and instrumental methods are summarized in this review. The prospects and reformative aspects for the future applications of these approaches in PV determination are also discussed.

Effects of different modified atmosphere treatments on lipid oxidation in spiced beef at different storage temperatures

The high moisture and nutrient contents of spiced beef make it popular with consumers but present challenges for its storage, as spoilage is a common phenomenon. Therefore, for identifying packaging methods to reduce spoilage during storage, this study investigated the effects of 5% O2 (low oxygen), 70% CO2 (high carbon dioxide), and 5% O2/70% CO2/25% N2 (compound group) on lipid oxidation in spiced beef in the test groups and a vacuum-packed group (control) at storage temperatures of 4, 25, and 60°C. The pH, thiobarbituric acid (TBA), anisidine value (AV), and peroxide value (POV) of the spiced beef were determined. Results indicated that 70% CO2 and storage at 4 and 25°C showed the strongest ability to inhibit the rancidity in spiced beef. The 5% O2 group delayed both initial oxidation and secondary oxidation of lipids. Although the compound group significantly inhibited the rancidity in spiced beef at 60°C, it could not maintain such inhibition for long. Among all the groups, the 70% CO2 group demonstrated maximum inhibition of initial lipid oxidation and suppressed the secondary oxidation of lipids for the longest time. Thus, the modified atmosphere packaging with O2 and CO2 can regulate the fat oxidation in meat products and effectively improve their flavor maintenance.

Evaluation of Lipid Oxidation, Volatile Compounds and Vibrational Spectroscopy of Silver Carp (Hypophthalmichthys molitrix) During Ice Storage as Related to the Quality of Its Washed Mince

Changes in the lipid oxidation of silver carp (Hypophthalmichthys molitrix) stored in ice for 14 days and that of its respective washed mince were evaluated. Total lipid, phospholipid, polyunsaturated fatty acid (PUFA) and monounsaturated fatty acid (MUFA) contents of the skin, belly flap and mince decreased as the storage time in ice increased. The washing process decreased the lipid contents but concentrated their phospholipid counterparts. The fish belly flap exhibited the highest thio-barbituric acid reactive substances (TBARS) value, while the mince had the lowest. 1-Hexanol, 1-octen-3-ol, and 1-hexanal were key volatile compounds detected in the belly flaps of fish stored for 7–14 days. Hexanal was the only major volatile compound found in washed mince prepared from fish stored for an extended period in ice, but in a much lower amount compared with that in the belly flap. FTIR (Fourier transform infra-red) spectra revealed a decrease in the number of cis double bonds, methylene groups and phosphate groups in lipids extracted from fish stored in ice for 7–14 days as compared with those extracted from fresh fish. Principle component analysis (PCA) revealed that the FT-Raman band at 1747 cm⁻¹ could be a potential marker for tracking the degree of lipid oxidation in the belly flap of silver carp stored in ice. In addition, IR bands indicating phosphate group (925, 825 cm⁻¹) in oil extracted from washed mince were correlated with the extent of the lipid oxidation of the raw material.

Removal and Inactivation of an Enveloped Virus Surrogate by Iron Conventional Coagulation and Electrocoagulation

It is imperative to understand the behavior of enveloped viruses during water treatment to better protect public health, especially in the light of evidence of detection of coronaviruses in wastewater. We report bench-scale experiments evaluating the extent and mechanisms of removal and/or inactivation of a coronavirus surrogate (ϕ6 bacteriophage) in water by conventional FeCl₃ coagulation and Fe(0) electrocoagulation. Both coagulation methods achieved ∼5-log removal/inactivation of ϕ6 in 20 min. Enhanced removal was attributed to the high hydrophobicity of ϕ6 imparted by its characteristic phospholipid envelope. ϕ6 adhesion to freshly precipitated iron (hydr)oxide also led to envelope damage causing inactivation in both coagulation techniques. Fourier transform infrared spectroscopy revealed oxidative damages to ϕ6 lipids only for electrocoagulation consistent with electro-Fenton reactions. Monitoring ϕ6 dsRNA by a novel reverse transcription quantitative polymerase chain reaction (RT-qPCR) method quantified significantly lower viral removal/inactivation in water compared with the plaque assay demonstrating that relying solely on RT-qPCR assays may overstate human health risks arising from viruses. Transmission electron microscopy and computationally generated electron density maps of ϕ6 showed severe morphological damages to virus' envelope and loss of capsid volume accompanying coagulation. Both conventional and electro- coagulation appear to be highly effective in controlling enveloped viruses during surface water treatment.

Rapid Screening of Mentha spicata Essential Oil and L-Menthol in Mentha piperita Essential Oil by ATR-FTIR Spectroscopy Coupled with Multivariate Analyses

Mentha piperita essential oil (EO) has high economic importance because of its wide usage area and health-beneficial properties. Besides health-beneficial properties, Mentha piperita EO has great importance in the flavor and food industries because of its unique sensory and quality properties. High-valued essential oils are prone to being adulterated with economic motivations. This kind of adulteration deteriorates the quality of authentic essential oil, injures the consumers, and causes negative effects on the whole supply chain from producer to the consumer. The current research used fast, economic, robust, reliable, and effective ATR-FTIR spectroscopy coupled chemometrics of hierarchical cluster analysis(HCA), principal component analysis (PCA), partial least squares regression (PLSR) and principal component regression (PCR) for monitoring of Mentha spicata EO and L-menthol adulteration in Mentha piperita EOs. Adulterant contents (Mentha spicata and L-menthol) were successfully calculated using PLSR and PCR models. Standard error of the cross-validation SECV values changed between 0.06 and 2.14. Additionally, bias and press values showed alteration between 0.06 and1.43 and 0.03 and 41.15, respectively. Authentic Mentha piperita was successfully distinguished from adulterated samples, Mentha spicata and L-menthol, by HCA and PCA analysis. The results showed that attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, coupled with chemometrics could be effectively used for monitoring various adulterants in essential oils.

Detection of Lipid Oxidation in Infant Formulas: Application of Infrared Spectroscopy to Complex Food Systems

 Fish- or algal oils have become a common component of infant formula products for their high docosahexaenoic acid (DHA) content. DHA is widely recognized to contribute to the normal development of the infant, and the European Commission recently regulated the DHA content in infant formulas. For many manufacturers of first-age early life nutrition products, a higher inclusion level of DHA poses various challenges. Long-chain polyunsaturated fatty acids (LC-PUFAs) such as DHA are very prone to oxidation, which can alter the organoleptic property and nutritional value of the final product. Traditional methods for the assessment of oxidation in complex systems require solvent extraction of the included fat, which can involve harmful reagents and may alter the oxidation status of the system. A rapid, efficient, non-toxic real-time method to monitor lipid oxidation in complex systems such as infant formula emulsions would be desirable. In this study, infrared spectroscopy was therefore chosen to monitor iron-induced oxidation in liquid infant formula, with conjugated dienes and headspace volatiles measured with GC-MS as reference methods. Infrared spectra of infant formula were recorded directly in mid- and near-infrared regions using attenuated total reflectance Fourier-transform (ATR-FTIR) and near-infrared (NIRS) spectrophotometers. Overall, good correlation coefficients (R2 > 0.9) were acquired between volatiles content and infrared spectroscopy. Despite the complex composition of infant formula containing proteins and sugars, infrared spectroscopy was still able to detect spectral changes unique to lipid oxidation. By comparison, near-infrared spectroscopy (NIRS) presented better results than ATR-FTIR: prediction error ATR-FTIR 18% > prediction error NIRS 9%. Consequently, NIRS demonstrates great potential to be adopted as an in-line or on-line, non-destructive, and sustainable method for dairy and especially infant formula manufacturers.

Intelligent evaluation of total polar compounds (TPC) content of frying oil based on fluorescence spectroscopy and low-field NMR

The purpose of this study was to construct a fusion model using probe-based and non-probe-based fluorescence spectroscopy and low-field nuclear magnetic resonance spectroscopy (Low-field NMR) for rapid quality evaluation of frying oil. Iron tetraphenylporphyrin (FeTPP) was selected as the probe to detect polar compounds in frying oil samples. Non-probe-based fluorescence spectroscopy and low-field NMR were employed to determine the fluorescence changes of antioxidants, triglycerides and fatty acids in frying oil samples. Compared to the models constructed using non-fusion data, the fusion-data models achieved a better regression prediction performance and correlation coefficients with values of 0.9837 and 0.9823 for the training and test sets, respectively. This study suggested that the multiple data fusion method was capable to construct better regression models to rapidly evaluate the quality of frying oil and other food with high oil contents.

Remedial role of exercise training to deep-fried oil-induced metabolic and histological changes in Wistar rats

Exercise training is a well-known lifestyle to maintain good health. The present study was conducted to explore the effect of regular exercise training (for 15 min) on biochemical, physiological, and histological changes in fried oil intake (5 g/kg body weight, for 5 weeks) with or without raw oil supplementation. Liver disease and heart muscle injury were accounted for by significant (p < .05) increase in liver and heart biomarker enzymes in serum. Creatinine and urea level were also significantly increased in the fried oil-fed group as a sign of kidney injury. But all the biological markers including triglycerides, low-density lipoprotein cholesterol (LDL-C) was decreased significantly (p < .05) in the exercise-trained rat group. These metabolic changes were substantiated by the histological study of respective organs. Therefore, people should avoid repeatedly deep-fried oil consumption rather than fresh ones though regular exercise training has been found to resolve these metabolic abnormalities. PRACTICAL APPLICATIONS: Exercise training is a common practice to reduce the onset of some metabolic abnormalities for example cardiovascular disease, non-alcoholic fatty liver disease, chronic kidney disease, and also prevents various cell and tissue damages. Repeated frying of vegetable oil not only reduces its nutritional value but also produce free fatty acids and other toxic compounds. The present study revealed that repeatedly heated vegetable oil consumption causes injuries in the heart, liver, kidney, and small intestine by the oxidative products. As a result, the level of biomarkers of these responsive organs was found to be elevated. But regular exercise training ameliorated these detrimental effects. So, in terms of public health concern, regular exercise is one of the best ways to keep the body fit especially those who are consuming deep-fried oil.

Fast, direct and in situ monitoring of lipid oxidation in an oil-in-water emulsion by near infrared spectroscopy

Lipid oxidation has implications on food, cosmetics and other fat containing products. Fatty acid autoxidation alters both the quality and safety of these products. Efficient and fast methods are needed to track lipid oxidation in complex systems. In this study, an oil-in-water emulsion (20% v/v of fish oil stabilized with high oleic sunflower lecithin) was subjected to iron-initiated oxidation. Conjugated dienes (CDs) were measured after fat extraction using a standardized method. Near infrared spectroscopy (NIRS) has been used to record chemical changes occurring during oxidation directly in the emulsion. Variations were noticed in different spectral regions. Partial least squares regression (PLSR) revealed correlations between conjugated diene values and NIRS spectra. High coefficients of determination (R2 = 0.967 and 0.996) were found for calibration and prediction respectively. The CD value was predicted from NIRS spectra with an error of 7.26 mmol eq. LH kg-1 oil (7.8% error). Limits of detection (LOD) and quantification (LOQ) of 4.65 and 15.5 mmol eq. LH kg-1 oil were estimated. NIRS is a rapid and simple method for measuring lipid oxidation (CD value) in an emulsion without prior fat extraction. NIRS can replace the reference methods that use hazardous solvents and consume time. Therefore, NIRS enables in-line monitoring for process and quality control.

Detection of lard in butter using Raman spectroscopy combined with chemometrics

There is a contentious need for robust and rapid methodologies for maintaining the authenticity of foods and food additives. The current paper presented a new Raman spectroscopy-based methodology for detection and quantification of lard in butter. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were successfully performed for the classification and discrimination of butter and lard-adulterated samples. Strong discrimination pattern was observed in the HCA analysis. Also, partial least squares regression and principal component regression (R² = 0.99) were applied for quantification of lard in butter samples. Quite favorable prediction capabilities were observed in the cross-validation of PLS and PCR analysis for the adulteration levels between 0% and 100% lard fat (w/w). Raman spectroscopy coupled chemometrics was employed effectively for quantification of lard fat in butter fat samples with easy, robust, effective, low-cost and reliable application in the quality control of butter.

Multi-sensor integration approach based on hyperspectral imaging and electronic nose for quantitation of fat and peroxide value of pork meat

The study assessed the feasibility of merging data acquired from hyperspectral imaging (HSI) and electronic nose (e-nose) to develop a robust method for the rapid prediction of intramuscular fat (IMF) and peroxide value (PV) of pork meat affected by temperature and NaCl treatments. Multivariate calibration models for prediction of IMF and PV using median spectra features (MSF) and image texture features (ITF) from HSI data and mean signal values (MSV) from e-nose signals were established based on support vector machine regression (SVMR). Optimum wavelengths highly related to IMF and PV were selected from the MSF and ITF. Next, recurring optimum wavelengths from the two feature groups were manually obtained and merged to constitute "combined attribute features" (CAF) which yielded acceptable results with (R_c² = 0.877, 0.891; RMSEC = 2.410, 1.109; R_p² = 0.790, 0.858; RMSEP = 3.611, 2.013) respectively for IMF and PV. MSV yielded relatively low results with (R_c² = 0.783, 0.877; RMSEC = 4.591, 0.653; R_p² = 0.704, 0.797; RMSEP = 3.991, 0.760) respectively for IMF and PV. Finally, data fusion of CAF and MSV was performed which yielded relatively improved prediction results with (R_c² = 0.936, 0.955; RMSEC = 1.209, 0.997; R_p² = 0.895, 0.901; RMSEP = 2.099, 1.008) respectively for IMF and PV. The results obtained demonstrate that it is feasible to mutually integrate spectral and image features with volatile information to quantitatively monitor IMF and PV in processed pork meat. Graphical abstract.

Effect of raw and repeatedly fried mustard oil intake on metabolic and organ histological changes in Wistar rat

Fried dietary oils often cause adverse health effects due to altered chemical and nutritional properties. In the present study with mustard oil, the effect of repeated frying (180°C for 10 min, three times) on chemical characteristics and oral intake of raw and fried mustard oil (5 g/kg for 5 weeks) in Wistar rats were investigated. Repeated frying caused oxidation reactions and free fatty acid content in mustard oil. This fried oil feeding to rats increased serum LDL cholesterol and triglycerides and decreased HDL leading to nonalcoholic fatty liver disease accounted by significant increment of liver enzymes (ALT, AST, ALP) compared with raw oil-fed group. Higher level of serum CK-MB and creatinine in fried oil-fed rats indicate disrupted kidney function. Histological findings of the respective organs ascertained metabolic abnormalities due to fried oil intake. Thus, the study suggests avoidance of using repeatedly fried oils in food products for better consumer health. PRACTICAL APPLICATIONS: Vegetable oil is a common ingredient of food products. Mustard oil is used in many countries both as raw and fried forms for various food preparations. When it is being fried at elevated temperatures in the presence of air, both thermal and oxidative decomposition take place which alter the nutritional and functional bioactive properties of the oil. The findings of the current study revealed the repeatedly fried mustard oil-induced detrimental effects on various organs of Wistar rats. Human beings consuming repeatedly fried mustard oil regularly might also face these acute problems. Thus in context to the public health issue, it is a message to avoid in taking repeated fried oils at household cooking or food industry to maintain better health.

Use of FTIR Spectroscopy and Chemometrics with Respect to Storage Conditions of Moldavian Dragonhead Oil

Oils often have similar properties and can be difficult to identify based on color, smell or taste alone. The present paper suggests the use of Fourier-transform infrared spectroscopy (FTIR) in combination with chemometric methods to explore similarities and differentiate between samples of Moldavian dragonhead oil subjected to different storage conditions. Dragonhead is a plant characterized by very good honey output and ease of cultivation. Principal component analysis (PCA) was applied to a standard, full range of FTIR spectra. Additionally, hierarchical cluster analysis (HCA) was employed to explore the organization of the samples in groups relative to their “proximity” (similarity), by way of Euclidean distance measurement. PC1 and PC2 accounted respectively for 85.4% and 10.1% of the total data variance. PC1 and PC2 were strongly, negatively correlated within the entire spectral range; the only exception was the region corresponding to νs(-C-Hvst, -CH2) vibrations (aliphatic groups in triglycerides), where PC2 was positively correlated. The use of FTIR spectral analysis revealed noticeable differences in the intensity of bands characteristic of the ageing processes (markers of oxidative processes, etc.) taking place in oleaginous samples and related to the processes of fatty acids oxidation.

Investigation on the quality diversity and quality-FTIR characteristic relationship of sunflower seed oils

Forty-one sunflower seed oil (SSO) products were collected to investigate their quality parameters before and after high-temperature and short-time (HTST) cooking, including peroxide value (PV), acid value (AV) and fatty acid (FA) composition. Their Fourier-transform infrared (FTIR) spectra were then scanned to explore the parameter-FTIR characteristic relationship using chemometrics with multiple linear regression (MLR) analysis. The PV and AV of uncooked products were in the range of 1.49-6.29 mmol kg-1 and 0.04-0.31 mg g-1, with the variation coefficient of 36.47% and 146.82%, respectively. They were mainly composed of palmitic acid (2.39-3.33%), stearic acid (1.76-2.54%), oleic acid (10.02-24.77%) and linoleic acid (66.42-83.62%). The parameter changes caused by HTST cooking were slight. SSO products from different countries might have significantly different FA composition, especially linoleic acid content (P < 0.05), and those with different shelf times might differ in PV (P < 0.05). In addition, the FTIR spectra of cooked and uncooked SSO showed the similarity degree values ranging from 0.67 to 0.97 and 0.72 to 0.97, respectively. All the spectra exhibited the characteristic bands of -C-H, -C[double bond, length as m-dash]O, -C-O- and [double bond, length as m-dash]CH2, in which 11 common bands as independent variables were selected to establish various FTIR characteristic-quality relationship models. The models of palmitic acid, oleic acid and linoleic acid were acceptable for their content predictions. Moreover, the cooked oils and uncooked oils could be completely distinguished by orthogonal partial least squares discriminant analysis due to the cooking-caused changes in FTIR spectrum. Production place and shelf time were the important factors related to the quality diversity of SSO, and FTIR spectroscopy combined with chemometrics was feasible for the simultaneous determination of various quality parameters.

Digital image colorimetric analysis for evaluating lipid oxidation in oils and its emulsion

Optical analytical images were captured by a digital camera, and lipid peroxidation was monitored using colorimetric determination. The Image-J method was shown to have comparable accuracy to the conventional titration (American Oil Chemists' Society) and UV-Vis spectroscopic methods. Over the PV range 3-14 meq.O₂/kg, a good correlation (R² = 0.9836) was found between the proposed method and UV-Vis method with an SD of ±0.0339 meq.O₂/kg. The range and accuracy of detection were determined from the changes in the Image-J intensity values. At equivalent PV, the limit of detection was 0.175 meq.O₂/kg and the limit of quantitation was 0.35 meq.O₂/kg. The proposed Image-J application can be used to develop fast and portable devices for monitoring peroxide values. These have potential applications in quality control for small-scale farmers and small and medium enterprises.

Fast and direct analysis of oxidation levels of oil-in-water emulsions using ATR-FTIR

Oxidation of omega-3 fatty acids is a major limitation on its enrichment in food and beverages. An efficient and simple method to monitor lipid oxidation in complex systems is essential to limit lipid oxidation during formulation and processing. Fish oil-in-water emulsions (20% v/v) were exposed to iron or free radical initiated oxidation. Conjugated dienes (CDs) were rapidly measured using a previously developed fat extraction method. Fourier transform infrared (FTIR) spectroscopy has been used to directly record chemical changes occurring during oxidation. Variations were noticed in different spectral regions despite the presence of broad water bands near 3400 and 1640 cm^-1. Partial least squares regression (PLSR) revealed correlations between CD values and full FTIR spectra (4000-600 cm^-1), and different spectral regions (e.g., 1800-1500 cm^-1, 1500-900 cm^-1). These correlations confirm that FTIR spectroscopy is a rapid and simple method for measuring lipid oxidation in complex foods without prior fat extraction.

Quantitative analysis of glycated albumin in serum based on ATR-FTIR spectrum combined with SiPLS and SVM

A rapid quantitative analysis model for determining the glycated albumin (GA) content based on Attenuated total reflectance (ATR)-Fourier transform infrared spectroscopy (FTIR) combining with linear SiPLS and nonlinear SVM has been developed. Firstly, the real GA content in human serum was determined by GA enzymatic method, meanwhile, the ATR-FTIR spectra of serum samples from the population of health examination were obtained. The spectral data of the whole spectra mid-infrared region (4000-600 cm^-1) and GA's characteristic region (1800-800 cm^-1) were used as the research object of quantitative analysis. Secondly, several preprocessing steps including first derivative, second derivative, variable standardization and spectral normalization, were performed. Lastly, quantitative analysis regression models were established by using SiPLS and SVM respectively. The SiPLS modeling results are as follows: root mean square error of cross validation (RMSECV_T) = 0.523 g/L, calibration coefficient (R_C) = 0.937, Root Mean Square Error of Prediction (RMSEP_T) = 0.787 g/L, and prediction coefficient (R_P) = 0.938. The SVM modeling results are as follows: RMSECV_T = 0.0048 g/L, R_C = 0.998, RMSEP_T = 0.442 g/L, and R_p = 0.916. The results indicated that the model performance was improved significantly after preprocessing and optimization of characteristic regions. While modeling performance of nonlinear SVM was considerably better than that of linear SiPLS. Hence, the quantitative analysis model for GA in human serum based on ATR-FTIR combined with SiPLS and SVM is effective. And it does not need sample preprocessing while being characterized by simple operations and high time efficiency, providing a rapid and accurate method for GA content determination.

Spectroscopic studies of the quality of WCO (Waste Cooking Oil) fatty acid methyl esters

Different kinds of biodiesel fuels become more and more attractive form of fuel due to their unique characteristics such as: biodegradability, replenishability, and what is more a very low level of toxicity in terms of using them as a fuel. The test on the quality of diesel fuel is becoming a very important issue mainly due to the fact that its high quality may play an important role in the process of commercialization and admitting it on the market. The most popular techniques among the wellknown are: molecular spectroscopy and molecular chromatography (especially the spectroscopy of the electron absorption and primarily the infrared spectroscopy (FTIR)).The issue presents a part of the results obtained with the use of spectroscopy of the electron absorption and in majority infrared spectroscopy FTIR selected for testing samples of the acid fats WCO (Waste Cooking Oil) types. The samples were obtained using laboratory methods from sunflower oil and additionally from waste animal fats delivered from slaughterhouses. Acid methyl esters were selected as references to present the samples. In order to facilitate the spectroscopic analysis, free glycerol, methanol, esters and methyl linolenic acid were measured