Preparation and characterisation of kaempferol composite carrier solid dispersion: evaluation of its application in preventing soybean oil spoilage.

Kaempferol (KPF) can be used as a natural antioxidant and food additive in food processing. However, the poor solubility of KPF limited its bioavailability and application. In order to improve the solubility of KPF, kaempferol composite carrier solid dispersion (KPF-CC-SD) was prepared and the process was optimised. When the ratio of KPF: CA (citric acid): Soluplus reached 1:4:6, the dissolution rate was the highest, and the sample was stable over 12 weeks. The characterisation results indicated that KPF-CC-SD exists in an amorphous form. Peroxidation value and acid value of soybean oil showed that the preservation effect of KPF-CC-SD was better than that of KPF, and the inhibition effect of KPF-CC-SD on acid value was better than that of butylated hydroxytoluene. In conclusion, KPF-CC-SD can change the solubility, crystal form and spatial stability of KPF through the carrier, which has a great application prospect in the field of food preservation.

Comparative evaluation of physicochemical and antimicrobial properties of rubber seed oil from different regions of Bangladesh.

In Bangladesh, the annual production of rubber seeds is typically left untapped although the seeds contained a high percentage of oil but underutilized without any value-added utilization. This study aims to evaluate the geographical effect on physicochemical properties, fatty acid composition and the antimicrobial activity of oil extracted from rubber seeds. Seeds were collected from three different regions of Bangladesh and the oil was extracted by the soxhlet method using n-hexane as a solvent. Results demonstrated that the geographical regions have some significant effect on the properties of rubber seed oil (RSO). The physicochemical properties of RSO varied from region to region. For example, the percent of yield, higher heating value, and flash point varied from 50.0 to 50.8 %, 31.8-33.3 kJ/g, and 237-245 °C, respectively. The chemical parameters, such as acid value, iodine value, and hydroxyl value varied from 13.3 to 18.2 mg KOH/g, 132-137 g I2/100g, and 47.7-55.8 mg KOH/g, respectively. Chromatographic analysis showed that RSO mainly contains palmitic, linoleic, linolenic, and stearic acid. Regional variations were also seen in the composition of these fatty acids. Most notably, regardless of the rubber seeds collected from various locations, RSO exhibited inhibitory activity against only gram positive bacteria. The zone of inhibition range for different tested gram positive bacteria was 2.33-11.17 mm irrespective of different RSO samples.

Decreasing acid value of fatty acid ethyl ester products using complex enzymes.

Recently, enzymatic method has been used to prepare biodiesel using various oils. But the high acid value of the biodiesel product using enzyme as a catalyst has been one issue. In this work, an attempt to reduce the acid value of fatty acid ethyl ester (FAEE) product to satisfy the specified requirement (AV ≤ 0.5 mgKOH/g), a complex enzyme-catalyzed method was used for the ethanolysis of Semen Abutili seed oil (SASO) (AV = 5.5 ± 0.3 mgKOH/g). The effects of various variables (constituents of complex enzyme, type and addition of water removal agent, time, temperature, enzyme addition load, substrate ratio) on the enzymatic reaction were investigated. The optimal reaction conditions were: 1% addition of liquid lipase Eversa® Transform 2.0% and 0.8% of enzyme dry powder CALB, reaction temperature 35°C, alcohol-oil ratio 9:1 (mol/mol), 0.8 g/g of 4A-MS and reaction time 24 h. Under the optimal reaction conditions, the FAEE yield was 90.8% ± 1.5% and its acid value was decreased from 12.0 ± 0.2 mgKOH/g to 0.39 ± 0.10 mgKOH/g. In further evaluating the feasibility of preparing FAEE from SASO, the FAEE products obtained under the optimal reaction conditions were purified and evaluated with reference to the ASTM D6751 standard for the main physicochemical indexes. The results obtained were in accordance with the requirements except for the oxidative stability.

A novel method for determination of peroxide value and acid value of extra-virgin olive oil based on fluorescence internal filtering effect correction.

Peroxide value (PV) and acid value (AV) are widely used indicators for evaluating oxidation degree of olive oils. Fluorescence spectroscopy has been extensively studied on the detection of oil oxidation, however, the detection accuracy is limited due to internal filtering effect (IFE). Due to the primary and secondary IFE, at least two wavelengths of absorption information are required. Least squares support vector regression (LSSVR) models for PV and AV were established based on two absorption coefficients (µa) at 375 nm and emission wavelength and one fluorescence intensity at corresponding wavelength. The regression results proved that the model based on 375 and 475 nm could reach the best performance, with the highest correlation coefficient for prediction (rp) of 0.889 and 0.960 for PV and AV respectively. Finally, the explicit formulations for PV and AV were determined by nonlinear least squares fitting, and the rp could reach above 0.94 for two indicators.

The bioprotective role of irradiated hibiscus against harmful effects of using repeatedly frying edible oil

Abstract Repeatedly frying process of dietary edible oil has a potential role in the generation of free radicals. Therefore, questions have always been raised as to whether, there is an efficient and economical method to reduce the harmful effects of repeated use of frying edible oil. Since hibiscus has been stated to have a wide variety of therapeutic effects, it was important to investigate its properties against harmful effects of free radicals. The current study aspires to find out whether irradiated powder of hibiscus has a protective role against adverse effects of repeated use of frying edible oil. Thirty-five adult male albino rats were equally assigned into five groups. First groupG1 was fed with normal diet as control group, meanwhile, groupG2 the diet mixed with fresh oil, G3 diet mixed with repeatedly frying oil only, G4 diet mixed with frying oil treated with hibiscus and G5 diet mixed with frying oil treated with irradiated hibiscus. Feeding duration was six weeks. Fatty acid analyses of oil as well as peroxide values were determined. Blood and liver samples were collected for biochemical analyses as well as histological study. Repeatedly heated cooked oil has significant increases in peroxide value, acid value, free fatty acid and both conjugated diene and triene compared with repeatedly frying oil treated with hibiscus. Also there are significant increases in cholesterol and triglyceride and impaired in liver functions in G3compared with others. In addition, relative to the hibiscus groups, there is a substantial reduction in oxygen consumption in G3. Both hibiscus as well as irradiated hibiscus attract attention in order to play a vital and economical role against harmful effects of frequent use of frying edible oil on some biological functions but, irradiated hibiscus was more effective.

Resumo O processo de fritura repetida de óleo comestível da dieta tem papel potencial na geração de radicais livres que podem ter efeitos prejudiciais em algumas funções biológicas. Portanto, sempre se questionou se existe uma maneira eficiente e econômica de prevenir ou pelo menos reduzir os efeitos nocivos do uso repetido de óleo comestível para fritar. Como o hibisco tem ampla variedade de efeitos terapêuticos, foi importante investigar suas propriedades como agente antioxidante contra os efeitos nocivos dos radicais livres. O presente estudo pretende descobrir se o pó irradiado de hibisco tem papel protetor contra os efeitos adversos do uso repetido de óleo comestível para fritar. Trinta e cinco ratos albinos machos adultos foram divididos igualmente em cinco grupos. O primeiro grupo G1 foi alimentado com dieta normal como grupo controle, enquanto o grupo G2 dieta misturada com óleo fresco, dieta G3 misturada com óleo de fritura repetida, dieta G4 misturada com óleo de fritura tratada com hibisco e dieta G5 misturada com óleo de fritura tratada com hibisco irradiado. A duração da alimentação foi de seis semanas. Foram determinadas as análises de ácidos graxos de óleo, bem como os valores de peróxidos. Amostras de sangue e fígado foram coletadas para análises bioquímicas e estudo histológico. O óleo cozido repetidamente aquecido tem aumentos significativos no valor de peróxido, valor de ácido, ácido graxo livre e dieno e trieno conjugados em comparação com óleo de fritura repetidamente tratado com hibisco. Também há aumentos significativos no colesterol e triglicérides e comprometimento das funções hepáticas no G3 em comparação com outros. Além disso, em relação aos grupos de hibiscos, há uma redução substancial no consumo de oxigênio no G3. Tanto o hibisco como o hibisco irradiado chamam atenção por desempenhar papel vital e econômico contra os efeitos nocivos do uso frequente de óleo comestível para fritar em algumas funções biológicas, mas o hibisco irradiado foi mais eficaz.

The bioprotective role of irradiated hibiscus against harmful effects of using repeatedly frying edible oil / O papel bioprotetor do hibisco irradiado contra os efeitos nocivos do uso de óleo comestível para fritar

Abstract Repeatedly frying process of dietary edible oil has a potential role in the generation of free radicals. Therefore, questions have always been raised as to whether, there is an efficient and economical method to reduce the harmful effects of repeated use of frying edible oil. Since hibiscus has been stated to have a wide variety of therapeutic effects, it was important to investigate its properties against harmful effects of free radicals. The current study aspires to find out whether irradiated powder of hibiscus has a protective role against adverse effects of repeated use of frying edible oil. Thirty-five adult male albino rats were equally assigned into five groups. First group"G1" was fed with normal diet as control group, meanwhile, group"G2" the diet mixed with fresh oil, "G3" diet mixed with repeatedly frying oil only, "G4" diet mixed with frying oil treated with hibiscus and "G5" diet mixed with frying oil treated with irradiated hibiscus. Feeding duration was six weeks. Fatty acid analyses of oil as well as peroxide values were determined. Blood and liver samples were collected for biochemical analyses as well as histological study. Repeatedly heated cooked oil has significant increases in peroxide value, acid value, free fatty acid and both conjugated diene and triene compared with repeatedly frying oil treated with hibiscus. Also there are significant increases in cholesterol and triglyceride and impaired in liver functions in "G3"compared with others. In addition, relative to the hibiscus groups, there is a substantial reduction in oxygen consumption in "G3". Both hibiscus as well as irradiated hibiscus attract attention in order to play a vital and economical role against harmful effects of frequent use of frying edible oil on some biological functions but, irradiated hibiscus was more effective.

Resumo O processo de fritura repetida de óleo comestível da dieta tem papel potencial na geração de radicais livres que podem ter efeitos prejudiciais em algumas funções biológicas. Portanto, sempre se questionou se existe uma maneira eficiente e econômica de prevenir ou pelo menos reduzir os efeitos nocivos do uso repetido de óleo comestível para fritar. Como o hibisco tem ampla variedade de efeitos terapêuticos, foi importante investigar suas propriedades como agente antioxidante contra os efeitos nocivos dos radicais livres. O presente estudo pretende descobrir se o pó irradiado de hibisco tem papel protetor contra os efeitos adversos do uso repetido de óleo comestível para fritar. Trinta e cinco ratos albinos machos adultos foram divididos igualmente em cinco grupos. O primeiro grupo "G1" foi alimentado com dieta normal como grupo controle, enquanto o grupo "G2" dieta misturada com óleo fresco, dieta "G3" misturada com óleo de fritura repetida, dieta "G4" misturada com óleo de fritura tratada com hibisco e dieta "G5" misturada com óleo de fritura tratada com hibisco irradiado. A duração da alimentação foi de seis semanas. Foram determinadas as análises de ácidos graxos de óleo, bem como os valores de peróxidos. Amostras de sangue e fígado foram coletadas para análises bioquímicas e estudo histológico. O óleo cozido repetidamente aquecido tem aumentos significativos no valor de peróxido, valor de ácido, ácido graxo livre e dieno e trieno conjugados em comparação com óleo de fritura repetidamente tratado com hibisco. Também há aumentos significativos no colesterol e triglicérides e comprometimento das funções hepáticas no "G3" em comparação com outros. Além disso, em relação aos grupos de hibiscos, há uma redução substancial no consumo de oxigênio no "G3". Tanto o hibisco como o hibisco irradiado chamam atenção por desempenhar papel vital e econômico contra os efeitos nocivos do uso frequente de óleo comestível para fritar em algumas funções biológicas, mas o hibisco irradiado foi mais eficaz.

How heated vegetable oil age? Effect of the container of heating on ageing.

This study compares the ageing process of heated oil with unheated oil and assesses the effect of container used in heating on ageing. Four types of oils were heated on glass, copper and iron. The samples were allowed to age for 1 year. Unheated oils generally produce peroxide faster (for unheated maximum increase in 6-month is 2907 % from 1.351 to 40.627 but for heated maximum increase is 6574 % from 1.91 to 127.476). But they develop secondary oxidation products slowly (for unheated maximum increase in 6-month is 884 % from 1.553 to 15.29 but for heated maximum increase is 191 % from 6.42 to 18.72). For most oil heating in copper produce more p-anisidine value during ageing. The acid value of only unheated oils decreases between 6 months to 1 year. For the 1st six-month rate of increase in saponification value in unheated oil is much higher. The DPPH inhibition activity also changes differently.

Effects of genotype, environment and their interaction on protein and amino acid contents in soybeans.

Soybean [Glycine max (L.) Merr.] is an important source of protein and oil. Genotype, environment and the interaction of genotype × environment influence the protein composition in soybean seeds. The main objectives of this study were to i) study the influence of genotype, environment and their interaction on soybean protein and amino acid contents; ii) evaluate the stability of soybean genotype across various environments, with a focus on soybeans grown in a northern latitude; and iii) identify the correlation between crude protein and critical amino acid value (CAAV). Twenty-three soybean genotypes were grown at four locations in Manitoba, Canada for two years (2018 and 2019). Soybean seeds were analyzed for protein and amino acids (nine essential amino acids and cysteine). The effects of genotype, environment and genotype × environment interaction on all traits were significant (P < 0.05). Genotype and environments explained the main part of variation for all traits. G13 and G15 cultivars performed better in favorable environments (bi > 1), and G22 cultivar showed greater resistance to environmental change. Protein and amino acids responded differently to various environments, but the optimal environments for greater soybean protein and amino acid remains to be established. The CAAV had a negative linear relationship with protein content in soybean (k = -0.17). This work expands our knowledge of the factors impacting the protein quality of soybeans grown in northern latitudes.

Thermal Degradation of Vegetable Oils.

Vegetable oils provide lipids and nutrition and provide foods with a desirable flavor, color, and crispy texture when used to prepare fried foods. However, the oil quality is degraded at elevated temperatures, and thus must be examined frequently because of the damage to human health. In this study, sunflower, soybean, olive, and canola oils were examined, and their properties were measured periodically at different elevated temperatures. The unsaturated triglyceride in oils reacted with the environmental oxygen or water vapor significantly changes in optical absorbance, viscosity, electrical impedance, and acid value. We used defect kinetics to analyze the evolution of these oil properties at elevated temperatures. The optical absorbance, viscosity, and electrical impedance follow the second-order, first-order, and zeroth-order kinetics, respectively. The rate constants of the above kinetics satisfy the Arrhenius equation. Olive oil has the lowest rate of color center and dynamic viscosity among the four oils, with the smallest pre-exponential factor and the largest activation energy, respectively. The rate constants of acid reaction also satisfy the Arrhenius equation. The activation energies of the polar compound and acid reaction are almost the same, respectively, implying that the rate constant is controlled by a pre-exponential factor if four oils are compared. Olive oil has the largest rate constant of acid reaction among the four oils, with the lowest pre-exponential factor.

Identification of aged-rice adulteration based on near-infrared spectroscopy combined with partial least squares regression and characteristic wavelength variables.

The long-term storage of rice will inevitably be involved in the deterioration of edible quality, and aged rice poses a great threat to food safety and human health. The acid value can be employed as a sensitive index for the determination of rice quality and freshness. In this study, near-infrared spectra of three kinds of rice (Chinese Daohuaxiang, southern japonica rice, and late japonica rice) mixed with different proportions of aged rice were collected. The partial least squares regression (PLSR) model with different preprocessing was constructed to identify the aged rice adulteration. Meanwhile, a competitive adaptive reweighted sampling (CARS) algorithm was used to extract the optimization model of characteristic variables. The constructed CARS-PLSR model method could not only reduce greatly the number of characteristic variables required by the spectrum but also improve the identification accuracy of three kinds of aged-rice adulteration. As above, this study proposed a rapid, simple, and accurate detection method for aged-rice adulteration, providing new clues and alternatives for the quality control of commercial rice.

Spectroscopic studies on thermal degradation and quantitative prediction on acid value of edible oil during frying by Raman spectroscopy.

The health risks posed by harmful substances resulting from the thermal degradation of frying oils are of great concern. Characteristic peak intensity ratios (PIRs) screened from Raman spectra were used to characterize the thermal degradation. High correlation coefficients between PIRs and acid values (AVs) of 0.972 (linear fitting), 0.984 (logarithmic function fitting), and 0.954 (linear fitting) for fried soybean oil, canola oil, and palm oil, were obtained at the PIRs of I1267/I1749, I1267/I1659, and I1267/I1749, respectively. The highly correlated PIRs common to the three oils were determined by Pearson's correlation coefficient combined with heat maps. To accommodate both linear and nonlinear features, a global model for predicting AVs of multi-varieties frying oils was constructed using a least-squares support vector machine algorithm, and the results performed well with a root mean square error of prediction of 0.016 and a ratio of prediction to deviation of 11.351. The whole results demonstrate that Raman spectroscopy could characterize the thermal degradation and has excellent quantitative analysis ability for food control based on AV in frying oils, thus providing a new approach to quality control of frying oils.

Untargeted Lipidomics Reveal Quality Changes in High-Moisture Japonica Brown Rice at Different Storage Temperatures.

Low temperatures are an effective way of delaying grain rancidity and deterioration. However, little is known about the difference in quality changes in high-moisture japonica brown rice at different storage temperatures. In this study, the storage quality changes in japonica brown rice with a 15.50% moisture content stored at 15 °C, 20 °C, and 25 °C were investigated. In addition, an untargeted lipidomics analysis coupled with gas chromatography and mass spectrometry (GC-MS) was applied to analyze the volatile compounds and metabolite changes in the high-moisture japonica brown rice. The results showed that storage at 15 °C could well maintain the color and aroma stability of the brown rice and delay the increase in fatty acid value (FAV). The lipidomics results showed that storage at 15 °C delayed glycerolipid and sphingolipid metabolism and reduced glycerophospholipid catabolism in the brown rice. The low-temperature environment regulated these three metabolic pathways to maintain higher contents of triglycerides (TG), phosphatidylserine (PS), abd phosphatidylethanolamine (PE), and lower contents of diglycerides (DG), OAcyl-(gamma-hydroxy) FA (OAHFA), ceramides (Cer), and glycosylceramides (Hex1Cer) in the high-moisture japonica brown rice, which maintained the storage stability of the brown rice. Our results proposed the cryoprotection mechanism of postharvest brown rice from the perspective of volatile compounds and metabolite changes, providing a foothold for the further exploration of low-temperature storage as a safe and efficient cryoprotectant in the grain storage field.

Isoflavones Play a Potential Role in Off-Flavour Scavenging, with a Key Role of IFS2 in Isoflavone Accumulation in Soybean Seeds.

Research background: Soybean (Glycine max (L.) Merr) is a nutrient-rich crop with a high protein content and various bioactive compounds with health-promoting properties. Nevertheless, it is poorly accepted as a food by consumers due to its off-flavour. Due to the ubiquitous presence of isoflavones in soybeans, their inherent antioxidant potential and inhibitory effect on lipoxygenase activity, their sensory properties are currently being considered to mitigate the off-flavour. Experimental approach: In the present study, the content and composition of isoflavones in 17 soybean cultivars are determined. The correlation between the isoflavone mass fraction and lipid peroxidation was also established, using thiobarbituric acid (TBA) value and carbonyl compound concentration as indices for the development of off-flavour. Cloning, gene expression analysis and in silico analysis of isoflavone synthase isoforms (IFS1 and IFS2) were also performed. Results and conclusions: The total isoflavone mass fraction in soybean genotypes ranged from (153.5±7.2) µg/g for PUSA 40 to (1146±43) µg/g for Bragg. There was a moderately negative correlation between the indices of off-flavour formation and the genistein/daidzein ratio (p<0.1). However, the correlation with total isoflavone mass fraction was found to be insignificant, indicating complex interactions. Higher protein-protein interactions for the predicted structure of IFS2 with other biosynthesis enzymes and its comparatively higher expression in the Bragg than that of IFS1 indicated its more important role in isoflavone synthesis. Novelty and scientific contribution: The genistein/daidzein mass ratio was found to be an important factor in controlling off-flavour. IFS2 was identified as key to produce soybeans with high isoflavone mass fraction and potentially lower off-flavour formation.

Metabolic mechanism of nitrogen modified atmosphere storage on delaying quality deterioration of rice grains.

Nitrogen modified atmosphere was an effective way to control pest infestation in grains. In this study, the quality changes of rice during nitrogen modified atmosphere packaging storage (N2-MAPS) were monitored. An un-targeted metabolomics method was used to detect the rice metabolites and explore the mechanism of N2-MAPS for delaying rice deterioration. In this study, two rice species were studied under N2-MAPS and conventional storage at 30 °C for 150 days. The quality changes of rice during storage were monitored. The results showed that N2-MAPS could retard the increase of fatty acid value and amylose content, and defer the decrease of enzyme activities. And N2-MAPS had no significant influence on texture characteristics of rice. The metabolomics results suggested some metabolites and pathways were affected by N2-MAPS and revealed that N2-MAPS could protect rice cells from oxidative damage, maintain cell integrity and stability by regulating the metabolism to delay the rice deterioration.

Effect of heating on disposal point of main edible oils available in Iran market.

Deep frying is the most common method used for food preparation worldwide, which can lead to several chemical changes in used fat or oil in frying process including oxidation and polymerization. This study aimed to determine the effect of heating and different storage conditions on the disposal point of four types of the most common edible oils available in the Iranian market without and with the presence of food in terms of acid value (AV) and total polar compounds (TPC). AV and TPC of three types of marketed sunflower oil (especially for frying, cooking, solid vegetable) and ghee heated at 110, 150, 180, and 200°C with a portable oil meter DOM-24 (ATAGO, Japan) were determined. They were measured without the presence of food at four different temperatures and four different times in five storage conditions and with the presence of frying food (chicken and potatoes) at 110°C for 20 min in three replicates. The results showed that the AV and TPC contents in the case of ghee were above national and international standards without the presence of food. Also, in the process of frying chicken and potato, the reusability of all the studied oils was not possible for the second time and reached the disposal point. The increase in the rate of AV and TPC of oils was: ghee (Kermanshahi oil) > liquid cooking oil > frying oil ≥ solid vegetable oil.

Lipid oxidation in fragrant rapeseed oil: Impact of seed roasting on the generation of key volatile compounds.

This work sought to identify the influence of roasting on lipid oxidation-derived volatile compounds in fragrant rapeseed oils (FROs) via gas chromatography-mass spectrometry and gas chromatography-ion mobility spectrometry. Seven volatiles could be regard as aroma-active compounds by application of odor activity value (OAV ≥ 1) calculation, and caused fatty-like, nutty-like, and green-like notes. After 60 min of roasting, the OAVs of hexanal, octanal, (E,E)-2,4-heptadienal, and nonanal in FROs were greater than 3. The same compounds, including hexanal, (E,E)-2,4-heptadienal, nonanal, 1-octanol, and nonanoic acid were also detected in the model systems of lipid oxidation. Notably, the values of p-anisidine, conjugated dienes, and conjugated trienes increased significantly (p < 0.05). Furthermore, correlation analysis showed that hexanal, (E,E)-2,4-heptadienal, and nonanal have a significant positive correlation with the oxidative degree of FROs (R = 0.70-0.94, p < 0.05). Thus, the three above-mentioned aldehydes could serve as important markers for FRO quality during roasting.

Utilization of Diaphragma juglandis extract as a natural antioxidant for improving the oxidative stability of soybean oil during deep frying.

Lipid oxidation significantly shortens the life of frying oils, and this challenge can be addressed by using antioxidants. This work aimed to investigate the effect of Diaphragma juglandis extract (DJE) on the oxidative stability of soybean oil during deep frying. Tert-butylhydroquinone (TBHQ) and tea polyphenol (TP) were applied as positive controls. A total of 31 polyphenols were determined in DJE, and catechin, quercitrin, taxifolin, quercetin 3-ß-d-glucoside, epicatechin, gallic acid, and 3,4-dihydroxybenzoic acid were the main components. The antioxidants effectively delayed the degradation of triglycerides and inhibited the increase in the contents of p-anisidine, oxidized triglyceride monomers, triglyceride dimers, and triglyceride oligomers, with DJE exhibiting better performance. Moreover, DJE showed better inhibitory effect on the formation of (E)-2-alkenals, (E,E)-2,4-alkadienals, 4-oxo-alkanals, primary alcohols, and secondary alcohols detected by 1H nuclear magnetic resonance than TBHQ and TP. Therefore, DJE has great potential as an excellent antioxidant in large-scale industrial applications.

Application of NIR spectroscopy for rapid quantification of acid and peroxide in crude peanut oil coupled multivariate analysis.

Two key parameters (acidity and peroxide content) for evaluation of the oxidation level in crude peanut oil have been studied. The titrimetric analysis was carried out for reference data collection. Then, near-infrared spectroscopy in combination with chemometric algorithms such as partial least square (PLS); bootstrapping soft shrinkage-PLS (BOSS-PLS); uninformative variable elimination-PLS (UVE-PLS), and competitive-adaptive reweighted sampling-PLS (CARS-PLS) were attempted and assessed. The correlation coefficients of prediction (Rp), root mean square error of prediction (RMSEP) and residual predictive deviation (RPD) were used to individually evaluate the performance of the models. Optimum results were noticed with CARS-PLS, 0.9517 ≤ Rc ≤ 0.9670, 0.9503 ≤ Rp ≤ 0.9637, 0.0874 ≤ RMSEP ≤ 0.5650, and 3.14 ≤ RPD ≤ 3.64. Therefore, this affirmed that the near-infrared spectroscopy coupled with CARS-PLS could be used as a simple, fast, and non-invasive technique for quantifying acid value and peroxide value in crude peanut oil.

Development of methods for determining free fatty acid contents in red colored oils.

Buah merah oil and red palm oil are red colored and unrefined edible oils. Because of this color characteristic, measuring acid value by titration method can be uncertain and subjective, so more accurate and objective methods are needed. Gas chromatography-flame ionization detector (GC-FID) and high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD) methods were developed to determine acid value in 3 buah merah oils and 1 red palm oil by measuring free fatty acid contents. The acid value was high in the order of titration > GC-FID > HPLC-ELSD in all samples. GC-FID method showed accurate and reliable results, whereas HPLC-ELSD showed rough data partly due to the non-linear standard curve and high limit of detection. Difference in acid value between titration method and GC-FID might be due to unrefined components that reacted with KOH titration solution. GC-FID can be used measuring free fatty acid contents in red colored oils. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10068-021-00964-2.

Quality Assessment of Deep-Frying Palm Oil by Impedimetric Sensing with a Simple and Economic Electrochemical Cell.

Quality control of deep-frying oil is a global public health concern. A simple and economic electrochemical chamber composed of two bare screen-printed carbon electrodes (working area: 78.54 × 102 cm2; distance: 0.0055 cm; cell constant: 0.70 × 10-2 cm-1) was constructed for precisely acquiring the impedimetric responses of a high-resistance palm oil sample (RSD < 7%, n = 3). Good correlations between the measured impedance data (charge transfer resistance and logarithmic output impedance (Log Z) obtained in the frequency region <0.1 Hz) and the regulatory quality indicators (total polar compounds and acid value) were achieved (R2 > 0.97), suggesting that the proposed impedimetric sensing method is useful for accurately assessing the deteriorated condition of repeated frying oil. Applications for rapid screening can also be realized because the measurement times of Log Z at any given perturbation frequency from 0.01-1 Hz were all less than 3 min.