Authentication of edible vegetable oils adulterated with used frying oil by Fourier Transform Infrared Spectroscopy

Analytical approaches for the determination of adulterated animal fats and vegetable oils in food and non-food samples

Edible oils and fats are crucial components of everyday cooking and the production of food products, but their purity has been a major issue for a long time. High-quality edible oils are contaminated with low- and cheap-quality edible oils to increase profits. The adulteration of edible oils and fats also produces many health risks. Detection of main and minor components can identify adulterations using various techniques, such as GC, HPLC, TLC, FTIR, NIR, NMR, direct mass spectrometry, PCR, E-Nose, and DSC. Each detection technique has its advantages and disadvantages. For example, chromatography offers high precision but requires extensive sample preparation, while spectroscopy is rapid and non-destructive but may lack resolution. Direct mass spectrometry is faster and simpler than chromatography-based MS, eliminating complex preparation steps. DNA-based oil authentication is effective but hindered by laborious extraction processes. E-Nose only distinguishes odours, and DSC directly studies lipid thermal properties without derivatization or solvents. Mass spectrometry-based techniques, particularly GC-MS is found to be highly effective for detecting adulteration of oils and fats in food and non-food samples. This review summarizes the benefits and drawbacks of these analytical approaches and their use in conjunction with chemometric tools to detect the adulteration of animal fats and vegetable oils. This combination provides a powerful technique with enormous chemotaxonomic potential that includes the detection of adulterations, quality assurance, assessment of geographical origin, assessment of the process, and classification of the product in complex matrices from food and non-food samples.

Modulation of starch structure, swallowability and digestibility of 3D-printed diabetic-friendly food for the elderly by dry heating

Elderly people often experience difficulty in swallowing and have impaired regulation of the nervous system. Furthermore, their blood glucose level can rise easily after eating. Therefore, functional foods that are easy to swallow and can maintain blood glucose at a lower level have been an important research topic in recent years. In this study, 3D printing was combined with dry heating to modify the starch in white quinoa and brown rice to develop whole grain foods with Osmanthus flavor that meet the dietary habits of the elderly. The samples were tested for printability, swallowing performance, and in vitro digestion. The results showed that after dry heating, all samples had shear-thinning properties and could pass through the extrusion nozzle of the printer smoothly. Both white quinoa and brown rice showed improved printability and self-support compared to the control. B45 (white quinoa, dry heating for 45 min) and C45 (brown rice, dry heating for 45 min) had significant elasticity and greater internal interaction strength during swallowing to resist disintegration of food particles during chewing. B45, C30, and C45, conformed to class 4 consistency and were characterized by easy swallowing of the diet. Further, dry heating resulted in greater resistance to enzymatic degradation of white quinoa and brown rice starch, with overall in vitro digestibility lower than the control.

Influence of cooking techniques on food quality, digestibility, and health risks regarding lipid oxidation

Foods undergo various physical and chemical reactions during cooking. Boiling, steaming, baking, smoking and frying are common traditional cooking techniques. At present, new cooking technologies including ultrasonic-assisted cooking, vacuum low-temperature cooking, vacuum frying, microwave heating, infrared heating, ohmic heating and air frying are widely studied and used. In cooking, lipid oxidation is the main reason for the change in lipid quality. Oxidative decomposition, triglyceride monomer oxidation, hydrolysis, isomerization, cyclization reaction and polymerization occurred in lipid oxidation affect lipids' quality, flavor, digestibility and safety. Meanwhile, lipid oxidation in cooking might cause the decline of lipid digestibility and increase of health risks. Compared with the traditional cooking technology, the new cooking technology that is milder, more uniform and faster can reduce the loss of lipid nutrition and produce a better flavor. In the future, the combination of various cooking technologies is an effective strategy for families to obtain healthier food.

Investigation of used cooking oil on the formation of FOG deposits in sewer line clogging

Fat, oil, and grease (FOG) deposits, resulting from saponification reaction, have been identified as the primary source of blockage of sewer pipes. This mainly emanates from the adhesion of these deposits on pipe walls, culminating in the sanitary sewer overflows (SSOs). This undesired phenomenon poses several challenges for municipalities, including environmental issues, health-related hazards, and an increase in incurred costs. Unlike the previous literature, the present study, for the first time, attempts to characterize the effect of used cooking oils (a mixture of different oils) as a perceived crux, triggering the genesis of deposits. The experimental results revealed that there exists a host of physical and chemical disparities between fresh oil calcium soaps (FOCSs) and used oil calcium soaps (UOCSs). Notably, when mixed with water, FOCSs produced non-miscible layers, whereas a homogenous, sticky, and viscous solution observed for UOCSs. Fourier transform infrared (FTIR) analysis casts light on the fact that the heating process would greatly influence the oil chemical structure and its resultant calcium soaps. In comparison with calcium chloride, as time elapsed, the optical microscope images illustrated that the calcium sulfate clots formation proceeded at an accelerated rate, delivering particles with larger sizes. Viscosity and adhesion are two prominent distinctions between soaps. In sharp contrast to soap produced from oil with a higher palmitic acid content, it was discerned that the oil containing less palmitic acid generates UOCSs with higher viscosity and adhesion than FOCSs. It can therefore be inferred that the distinct chemical structures driven by high temperature during the cooking process produce soaps with different characteristics as compared with fresh oil. This phenomenon would have a profound impact on the formation of the deposits in sewer lines.

Microbial diversity of milk ghee in southern Gansu and its effect on the formation of ghee flavor compounds

Ghee is a traditional Tibetan dairy product with high-fat content, low yield, plasticity, caseation, and rich nutrition. In this study, we analyzed the diversity of microbial communities in yak milk and ghee samples at high and low altitudes, especially the Lactobacillus genus, and further used metabolomic techniques to compare the differences in metabolites in yak ghee at different altitudes. The results showed that the increase in altitude had a significant and generally inhibitory effect on the microbial community diversity in milk ghee, and yak milk at high altitude was abundant in nutrients, which could antagonize the negative impact of increased altitude. Using non-targeted metabolomics, we infer the composition of flavor compounds in ghee: nine kinds of carboxylic acids, 11 kinds of esters, six kinds of ketones, two kinds of alcohols, and four kinds of alkene compounds, among which the key flavor compounds are dl-2-(acetylamino)-3-phenylephrine acid, 1-(4-methoxyphenyl)-2-propanone, sebacic acid, Lysope 18:1, and uracil 1-beta-d-arabinofuranoside. These flavor substances are found in Lactococcus, Lactobacillus, and Streptococcus. With the participation of Lactobacillus, it is synthesized through biosynthesis of alkaloids derived from ornithine, lysine, and nicotine acid and glyoxylate and decarboxylate metabolism, among which Lactococcus plays a key role. In this study, a variety of lactic acid bacteria related to ghee fermentation were screened out, revealing the composition of volatile flavor compounds in Gannan yak milk ghee in the Qinghai-Tibet Plateau and providing a reference for further key volatile flavor compounds and the formation mechanism of flavor compounds.

Statistical FT-IR Spectroscopy for the Characterization of 17 Vegetable Oils

Vegetable oils have been utilized for centuries in the food, cosmetic, and pharmaceutical industries, and they contribute beneficially to overall human health, to active skincare, and to effective treatments. Monitoring of the vegetable oils is carried out by the methods described in the European Pharmacopeia, which is time-consuming, has poor repeatability, and involves the use of toxic organic chemicals and expensive laboratory equipment. Many successful studies using IR spectroscopy have been carried out for the detection of geographical origin and adulteration as well as quantification of oxidation parameters. The aim of our research was to explore FT-IR spectroscopy for assessing the quality parameters and fatty acid composition of cranberry, elderberry, borage, blackcurrant, raspberry, black mustard, walnut, sea buckthorn, evening primrose, rosehip, chia, perilla, black cumin, sacha inchi, kiwi, hemp, and linseed oil. Very good models were obtained for the α-linolenic acid and linoleic acid contents, with R2 = 1.00; Rv2 values of 0.98, 0.92, 0.89, and 0.84 were obtained for iodine value prediction, stearic acid content, palmitic acid content, and unsaponifiable matter content, respectively. However, we were not able to obtain good models for all parameters, and the use of the same process for variable selection was found to be not suitable for all cases.

A Solvent-Free Approach to Crosslinked Hydrophobic Polymeric Coatings on Paper Using Vegetable Oil

Hydrophobic coatings are of utmost importance for many applications of paper-based materials. However, to date, most coating methods demand vast amounts of chemicals and solvents. Frequently, fossil-based coating materials are being used and multiple derivatization reactions are often required to obtain desired performances. In this work, we present a solvent-free paper-coating process, where olive oil as the main biogenic component is being used to obtain a hydrophobic barrier on paper. UV-induced thiol-ene photocrosslinking of olive oil was pursued in a solvent-free state at a wavelength of 254 nm without addition of photoinitiator. Optimum reaction conditions were determined in advance using oleic acid as a model compound. Paper coatings based on olive oil crosslinked by thiol-ene reaction reach water contact angles of up to 120°. By means of Fourier transform infrared spectroscopy and differential scanning calorimetry, a successful reaction and the formation of a polymer network within the coating can be proven. These results show that click-chemistry strategies can be used to achieve hydrophobic polymeric paper coatings while keeping the amount of non-biobased chemicals and reaction steps at a minimum.

Advanced process analytical tools for identification of adulterants in edible oils - A review

This review summarizes the use of spectroscopic processes-based analytical tools coupled with chemometric techniques for the identification of adulterants in edible oil. Investigational approaches of process analytical tools such asspectroscopy techniques, nuclear magnetic resonance (NMR), hyperspectral imaging (HSI), e-tongue and e-nose combined with chemometrics were used to monitor quality of edible oils. Owing to the variety and intricacy of edible oil properties along with the alterations in attributes of the PAT tools, the reliability of the tool used and the operating factors are the crucial components which require attention to enhance the efficiency in identification of adulterants. The combination of process analytical tools with chemometrics offers a robust technique with immense chemotaxonomic potential. These involves identification of adulterants, quality control, geographical origin evaluation, process evaluation, and product categorization.

Evaluation of Thermochemical Characteristics and Pyrolysis of Fish Processing Waste for Renewable Energy Feedstock

The necessity of energy is continuously increasing, whereas fossil fuel sources are gradually depleting. To mitigate this problem, fish processing waste of the bluespotted stingray (Neotrygon kuhlii), available in the Borneo region, was investigated for an alternative feedstock of bioenergy production. The fish wastes are hazardous for the environment, whereas the biodiesel from fish waste is pollution-free and produces less contaminant gas and carbon dioxide than fossil fuel. From the proximate analysis, the moisture content, volatile matter, fixed carbon, and ash content of the fish waste were achieved as 4.88%, 63.80%, 15.03%, and 16.29%, respectively. The proportion of carbon, hydrogen, nitrogen, sulfur, and oxygen was found as 42.06%, 5.99%, 10.77%, 0.91%, and 40.27%, respectively, from the ultimate analysis. The calorific value was 21.53 MJ/kg, which would be highly effective in biofuel production. The morphology analysis results of the biomass are favorable for renewable energy sources. The major bondage between carbon and hydrogen and oxygen was found using Fourier transform infrared spectroscopy. The thermogravimetric analysis and derivative thermogravimetry revealed that the highest weight loss occurred at 352 °C temperature with a decomposition rate of 4.57 wt.%/min in pyrolysis circumstances, and at 606 °C temperature with a decomposition rate of 3.77 wt.%/min in combustion conditions. In the pyrolysis process for 25 °C/min heating rate, the yield of biochar, bio-oil, and bio-syngas was found as 33.96, 29.34, 23.46% at 400 °C, 47.72, 49.32, 33.87% at 500 °C, and 18.32, 21.34, 42.37% at 600 °C, respectively. The characteristics and pyrolysis yields of fish waste are suitable for being an effective renewable energy source.

The application of machine-learning and Raman spectroscopy for the rapid detection of edible oils type and adulteration

Raman spectroscopy is an emerging technique for the rapid detection of oil qualities. But the spectral analysis is time-consuming and low-throughput, which has limited the broad adoption. To address this issue, nine supervised machine learning (ML) algorithms were integrated into a Raman spectroscopy protocol for achieving the rapid analysis. Raman spectra were obtained for ten commercial edible oils from a variety of brands and the resulting spectral dataset was analyzed with supervised ML algorithms and compared against a principal component analysis (PCA) model. A ML-derived model obtained an accuracy of 96.7% in detecting oil type and an adulteration prediction of 0.984 (R²). Several ML algorithms also were superior than PCA in classifying edible oils based on fatty acid compositions by gas chromatography, with a faster readout and 100% accuracy. This study provided an exemplar for combining conventional Raman spectroscopy or gas chromatography with ML for the rapid food analysis.

Effect of chia oil and pea protein content on stability of emulsions obtained by ultrasound and powder production by spray drying

Chia oil is susceptible to oxidation and to make this oil application into foodstuffs possible, chia-oil based microparticles were produced. Oil-in-water emulsions were produced by ultrasound and their stability was maximized using a central composite rotational design (X₁: pea protein X₂: oil concentration). Hi-Cap^® 100 (HC) or maltodextrin (MD) were used as carrier agents in spray drying. The validated formulation with 13.50% (w/w) oil and 3.87% (w/w) pea protein presented the best stability conditions (no phase separation for 7 days, monomodal size distribution, and 1.59 μm of moda diameter). Particles showed high encapsulation efficiency (87.71 and 91.97% for MD and HC, respectively) and low water activity and moisture values (0.114-0.150% and 2.64-3.41%, respectively). HC particles exhibited better physicochemical and structural characteristics, apart from their good reconstitution, which shows the potential of this approach as a viable alternative for the use of rich-plant ingredients, such as chia oil and pea protein.

An overview of recent advances and applications of FT-IR spectroscopy for quality, authenticity, and adulteration detection in edible oils

Authenticity and adulteration detection are primary concerns of various stakeholders, such as researchers, consumers, manufacturers, traders, and regulatory agencies. Traditional approaches for authenticity and adulteration detection in edible oils are time-consuming, complicated, laborious, and expensive; they require technical skills when interpreting the data. Over the last several years, much effort has been spent in academia and industry on developing vibrational spectroscopic techniques for quality, authenticity, and adulteration detection in edible oils. Among them, Fourier transforms infrared (FT-IR) spectroscopy has gained enormous attention as a green analytical technique for the rapid monitoring quality of edible oils at all stages of production and for detecting and quantifying adulteration and authenticity in edible oils. The technique has several benefits such as rapid, precise, inexpensive, and multi-analytical; hence, several parameters can be predicted simultaneously from the same spectrum. Associated with chemometrics, the technique has been successfully implemented for the rapid detection of adulteration and authenticity in edible oils. After presenting the fundamentals, the latest research outcomes in the last 10 years on quality, authenticity, and adulteration detection in edible oils using FT-IR spectroscopy will be highlighted and described in this review. Additionally, opportunities, challenges, and future trends of FT-IR spectroscopy will also be discussed.

Comparison of near infrared spectroscopy and Raman spectroscopy for the identification and quantification through MCR-ALS and PLS of peanut oil adulterants

Peanut oil is considered one of the best frying oils, and, consequently there is an increasing worldwide demand. This has led to adulteration practices with unhealthy, synthetic or less expensive oils which raises concerns related with public health safety. Therefore, there is a high need for rapid, versatile, low-cost and reliable analytical methods, such as vibrational spectroscopic techniques, capable of identifying and quantifying the respective adulteration. The objective of this work focused on the application of two different vibrational spectroscopic techniques (NIR and Raman spectroscopy) for the qualitative and quantitative analysis of two adulterants in pure peanut oil, namely corn oil and vegetable oil. For the quantitative analysis two chemometric methods, namely PLS and MCR-ALS, were compared while for the qualitative analysis only MCR-ALS was tested. The analysis of peanut oil adulteration was performed by adding each adulterant individually and also by blending the peanut oil with both adulterants simultaneously. A total of 69 samples were analyzed, which was comprised by two sets of 20 samples each containing just one adulterant and another set of 29 samples containing both adulterants. Several pre-processing techniques were tested. The qualitative analysis performed by MCR-ALS allowed the identification of all the adulterants using both NIR and Raman spectra, with correlation coefficients higher than 0.99. For the quantification, none of the chemometric methods as well as the vibrational spectroscopic techniques tested showed significant better results. Nonetheless, the determination coefficients and the relative percentage errors for the validation samples for most of the developed models were higher than 0.98 and lower than 15%, respectively. Concluding, MCR-ALS was capable of correctly extracting the spectral profiles of all the adulterants in very complex mixtures (as the pure spectra of the adulterants and peanut oil are very similar) and both MCR-ALS and PLS were able to quantify the adulteration with low RE. To the best of our knowledge, it was the first time that MCR-ALS was used for the qualitative analysis of peanut oil adulteration (with all adulterants added simultaneously) and MCR-ALS and PLS were compared for the quantification of peanut oil adulteration using both NIR and Raman spectroscopy.

A simple and quick method to detect adulterated sesame oil using 3D fluorescence spectra

Adulterated sesame oil seriously damages the interests of consumers and the health of market. In this paper, a simple, fast and real-time model for identifying adulterated sesame oil (ASO) was proposed by combining 3D fluorescence spectra with wavelet moments (WMs). First, noise and data volume of the experimental data were reduced by wavelet multiresolution decomposition (WMRSD), which improved the stability and real-time of the model. Next, WMs were used to extract the features of the 3D fluorescence spectra and proved to be effective by hierarchical clustering results. Then, the qualitative quality of WMs of the same orders, different orders and the combinations were evaluated by Dunn's validity index (DVI), and the rules were given, respectively. Finally, the target WMs for identifying ASO were determined. This model is simple and fast, and expandable to online measurement, providing a reference for identification and adulteration of vegetable oils.

Comprehensive Review on Application of FTIR Spectroscopy Coupled with Chemometrics for Authentication Analysis of Fats and Oils in the Food Products

Currently, the authentication analysis of edible fats and oils is an emerging issue not only by producers but also by food industries, regulators, and consumers. The adulteration of high quality and expensive edible fats and oils as well as food products containing fats and oils with lower ones are typically motivated by economic reasons. Some analytical methods have been used for authentication analysis of food products, but some of them are complex in sampling preparation and involving sophisticated instruments. Therefore, simple and reliable methods are proposed and developed for these authentication purposes. This review highlighted the comprehensive reports on the application of infrared spectroscopy combined with chemometrics for authentication of fats and oils. New findings of this review included (1) FTIR spectroscopy combined with chemometrics, which has been used to authenticate fats and oils; (2) due to as fingerprint analytical tools, FTIR spectra have emerged as the most reported analytical techniques applied for authentication analysis of fats and oils; (3) the use of chemometrics as analytical data treatment is a must to extract the information from FTIR spectra to be understandable data. Next, the combination of FTIR spectroscopy with chemometrics must be proposed, developed, and standardized for authentication and assuring the quality of fats and oils.

Potential of solid lipid microparticles covered by the protein-polysaccharide complex for protection of probiotics and proanthocyanidin-rich cinnamon extract

Probiotics and proanthocyanidin-rich cinnamon extract (PRCE) have numerous potential health benefits, but they are very sensitive to degradation in various environmental conditions. Additionally, the combination of these two materials into a single structure could possibly enhance their therapeutic properties. Thus, the aim of this study was to produce and evaluate the solid lipid microparticles covered by electrostatic interactions of polymers in which Lactobacillus paracasei (BGP1) and Bifidobacterium animalis subsp. lactis (BLC1) were either encapsulated alone or co-encapsulated with PRCE. Through turbidimetric titration and zeta potential measurement, the optimum coacervates were obtained at a pH of 4.2 with the protein:polysaccharide mixing ratio of 6:1. Along with quantification of the probiotics, total phenolic compounds, and proanthocyanidins, morphological and physicochemical characterizations were performed during storage for 120 days at both 7 and 25 °C. All the produced powders had similar morphological and physicochemical properties. The treatments with BLC1 and 5% PRCE presented greater encapsulation efficiencies for probiotic, phenolics, and proanthocyanids with 98.59% ± 0.45, 119.49% ± 4.21, and 81.25% ± 1.9, respectively. Additionally, there was greater viability for BLC1 (9.30 ± 0.16 log CFU / g) after 120 days of storage at 7 °C. In conclusion, solid lipid particles with BLC1 and 5% PRCE are a promising solution for the preservation and consumption of both materials.

Superhydrophobic Nickel-Electroplated Carbon Fibers for Versatile Oil/Water Separation with Excellent Reusability and High Environmental Stability

Superhydrophobic filtrating materials have been widely developed for rapid removal or collection of oils from oil/water mixture due to the increasing water pollution caused by oil spills and oil-contaminated wastewater. However, poor reusability, superhydrophobic failure in harsh environments, and that only heavy oil or light oil was separated from water seriously restricted their practical application. Herein, superhydrophobic carbon fibers were first fabricated using a novel nickel electroplating for versatile oil/water separation with excellent reusability and high environmental stability. The interconnected nanometer-scale nickel grains formed on the micrometer-scale fibers and fluoroalkylsilane molecules enabled the fibers to be superhydrophobic with the water contact angle (CA) of ∼159.1° and superoleophilic with the oil CA of ∼0°. The nickel coating contributed to the improvement of the bonding strength, tensile strength, and oxidation resistance of the fibers. The as-prepared fibers could be applied for the separation of heavy or light oil/water mixtures with separation efficiencies above 99.1%, during which the oil content in the separated water all remained below 78 ppm. The fibers also realized the highly efficient separation of dichloromethane and various harsh environmental solutions such as hot water, acid, alkali, and salt. The superhydrophobicity of the fluorinated nickel-coated carbon fibers still remained even after 100 cycles of separation and 24 months of storage in air, demonstrating outstanding durability of the fibers. These novel superhydrophobic carbon fibers had promising potentials for versatile oil/water separation in practical applications.

Rapid Classification and Quantification of Camellia (Camellia oleifera Abel.) Oil Blended with Rapeseed Oil Using FTIR-ATR Spectroscopy

Currently, the authentication of camellia oil (CAO) has become very important due to the possible adulteration of CAO with cheaper vegetable oils such as rapeseed oil (RSO). Therefore, we report a Fourier transform infrared (FTIR) spectroscopic method for detecting the authenticity of CAO and quantifying the blended levels of RSO. In this study, two characteristic spectral bands (1119 cm^-1 and 1096 cm^-1) were selected and used for monitoring the purity of CAO. In combination with principal component analysis (PCA), linear discriminant analysis (LDA), and partial least squares regression (PLSR) analysis, qualitative and quantitative methods for the detection of camellia oil adulteration were proposed. The results showed that the calculated I₁₁₁₉/I₁₀₉₆ intensity ratio facilitated an initial check for pure CAO and six other edible oils. PCA was used on the optimized spectral region of 1800-650 cm^-1. We observed the classification of CAO and RSO as well as discrimination of CAO with RSO adulterants. LDA was utilized to classify CAO from RSO. We could differentiate and classify RSO adulterants up to 1% v/v. In the quantitative PLSR models, the plots of actual values versus predicted values exhibited high linearity. Root mean square error of calibration (RMSEC) and root mean square error of cross validation (RMSECV) values of the PLSR models were 1.4518%-3.3164% v/v and 1.7196%-3.8136% v/v, respectively. This method was successfully applied in the classification and quantification of CAO adulteration with RSO.

Authentication of Eucommia ulmoides Seed Oil Using Fourier Transform Infrared and Synchronous Fluorescence Spectroscopy Combined with Chemometrics

Eucommia ulmoides is a traditional Chinese herb whose seeds can be used to produce edible oils. Fourier transform infrared (FTIR) and synchronous fluorescence spectroscopic (SyFS) spectra of Eucommia ulmoides seed oil (EUSO) are lacking. The relevant functional and fluorescent groups were determined by FTIR and SyFS techniques for discriminating adulteration of EUSO, respectively. FTIR and SyFS spectra of EUSO and six common-used vegetable oils were recorded from 4000-400 cm^-1 and 250-700 nm at wavelength interval of 60 nm, respectively. Principal component analysis (PCA), linear discriminant analysis (LDA), cluster analysis (CA) and partial least square (PLS) regression was used for qualitative and quantitative calibration of EUSO adulteration. The FTIR spectral regions of 1429-1377 cm^-1 and 1128-1110 cm^-1 based on PCA, LDA, and CA, and the PCA of SyFS spectral regions of 600-700 nm and 300-500 nm were evaluated for qualitative differentiation of EUSO adulteration. The recognition rate of PCA validation was found to be 100% by FTIR regions. PLS calibration was optimal by the spectral normalization vector treatment in the two FTIR spectral regions and SyFS spectra were combined with characteristic absorption peak area, which can achieve quantitative detection of EUSO adulteration. The two techniques are useful for EUSO adulteration detection at levels down to 1% and 0.48% (w/w), respectively. The results indicated that spectral information obtained by FTIR and SyFS of EUSO can be used for qualitative and quantitative analysis of EUSO adulteration with the advantages of high sensitivity, simplicity, and rapidness.

Calibrated Optical Markers to Study Thermal Degradation in Edible Oils Using Raman and Optical Transmission Spectroscopy

An "all optical" methodology, including Raman and optical transmission spectroscopy, is presented to study the thermal degradation in edible oils. Oils rich in monounsaturated (MU), polyunsaturated (PU), and saturated (S) fatty acids (FA) were heated above and below their smoke point (∼230 ℃). While the intensity (I) of the identified saturated (C-C, 1440 cm^-1) FA Raman marker did not change appreciably, the identified unsaturated (C=C, 1265 cm^-1) FA marker decreased in these oils when heated above the smoke point. A Raman parameter, I₁₂₆₅/I₁₄₄₀, designating thermal degradation, is proposed that was found to decrease consistently for the PUFA-rich and MUFA-rich oils when heated above the smoke point, while the SFA-rich oil did not degrade at all over the whole temperature range. An optical transmission marker at 2140 nm was identified that decreased consistently with increased thermal stressing. These markers can be calibrated with the variations in the quantitative iodine value, an industrial benchmark for the degree of unsaturation, for thermally stressed oils.

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.

Traditional Tibetan Ghee: Physicochemical Characteristics and Fatty Acid Composition

Fifty traditional Tibetan ghee (TTG) varieties were collected and analyzed their systematic characteristic indices, including physicochemical parameters, minerals, fatty acid composition, and thermal behavior. Results show that TTG contains a large amount of fat (71.68%-93.3%) and a small quantity of protein (0.51%-1.81%). The acid and peroxide values of TTG vary from 0.02 to 1.30 mg/g and 0.07 to 5.93 meq/kg, respectively. The content of minerals varied with altitude level and region significantly (p < 0.05), and the regional variations of fatty acids in TTG were also observed significantly, these differences may be due to the high unsaturated fatty acids level in the cow diets.

Improving the recycling technology of waste cooking oils: Chemical fingerprint as tool for non-biodiesel application

Samples of sunflower Waste Cooking Oils (WCOs) subjected to several cycles of frying were treated with water under four different combinations of temperature and pH. Several aspects of the chemical composition of edible, non-treated and processed samples was determined by three different analytic techniques: headspace Solid-Phase Microextraction (HS-SPME) coupled with gas-chromatography (GC), ¹H NMR spectroscopy and ESI-MS spectrometry. Thus, a characteristic chemical fingerprint of each sample was derived and proposed as useful set of tools for the optimization of recycling of WCOs. On the basis of the presented results, a mini-plant for the production of bio-lubricants and bio-solvents with a circular economy approach was designed and herein described.

Effects of storage condition on the physicochemical characteristics of sunflower seed oil

The effects of storage condition on the physicochemical characteristics of sunflower seed oil (SSO) were investigated, to understand the required conditions and the typical indicators for its quality control. The changes of SSO in peroxide value (PV), acid value (AV), fatty acid (FA) composition, Fourier transform infrared (FTIR) spectrum and volatile compound (VC) during 11 month storage under seven different conditions, were analyzed. The PVs and AVs of the seven groups all increased with time, but the PVs fluctuated strongly during the last 4 months. The between-group differences in PV and AV indicated that light-exposure and high-temperature (≥40 °C) both accelerated the production and degradation of primary oxidation products of FA. However, the FA composition of SSO did not obviously change regardless of storage condition and time, as well as its FTIR characteristics. By contrast, its VC composition was significantly changed by light-exposure and high-temperature (≥55 °C). 3-Methyl-2,5-furandione, acetic acid/1-phenylethyl ester, 2-pentyl-furan and limonene might be the main VCs related to the desirable flavor, in which 3-methyl-2,5-furandione in all the groups showed a significantly decreased percentage of VC composition during storage. Light-exposure and high-temperature enhanced the accumulation of aldehydes, especially hexanal and (E)-2-heptenal, which principally contributed to the undesirable flavor of SSO. 3-Methyl-2,5-furandione, hexanal and (E)-2-heptenal were proposed to be marker compounds for its quality control. A low-temperature and dark condition is necessary for SSO to remain a desirable flavor.

Sunflowerseed oil needs a low-temperature and dark condition to remain flavor by reducing the changes of 3-methyl-2,5-furandione, hexanal and 2-heptenal.

A review on the application of vibrational spectroscopy to the chemistry of nuts

Nuts are highly appreciated due to their nutritional relevance and flavour, being the source of many desirable and healthy compounds as polyunsaturated fatty acids and antioxidants. Their characterization became the target of many studies in the last years through conventional analytical techniques as chromatographic ones. Due to the limitations associated to these techniques, as time, cost and environmental concerns, spectroscopic techniques have been increasingly pointed as reliable alternatives. Either applied to raw materials quality control or to more complex process, as industrial in-line monitoring, spectroscopic techniques, namely vibrational spectroscopy, are gathering strong acceptance. This paper presents a review on the application of vibrational spectroscopy, infrared and Raman, to nuts characterization. Estimates of several qualitative and quantitative parameters, origin authentication and/or adulteration in almonds, peanuts, pine nuts, hazelnuts, walnuts, Brazil nuts, cashews, chestnuts and pistachios will be covered. Advantages and limitations of these techniques and future trends will also be discussed.

Fast classification of hazelnut cultivars through portable infrared spectroscopy and chemometrics

The authentication and traceability of hazelnuts is very important for both the consumer and the food industry, to safeguard the protected varieties and the food quality. This study investigates the use of a portable FTIR spectrometer coupled to multivariate statistical analysis for the classification of raw hazelnuts. The method discriminates hazelnuts from different origins/cultivars based on differences of the signal intensities of their IR spectra. The multivariate classification methods, namely principal component analysis (PCA) followed by linear discriminant analysis (LDA) and partial least square discriminant analysis (PLS-DA), with or without variable selection, allowed a very good discrimination among the groups, with PLS-DA coupled to variable selection providing the best results. Due to the fast analysis, high sensitivity, simplicity and no sample preparation, the proposed analytical methodology could be successfully used to verify the cultivar of hazelnuts, and the analysis can be performed quickly and directly on site.