Total Polar Materials Research Articles

FORMATION OF 3-MONOCHLORO-1,2-PROPANEDIOL FATTY ACID ESTERS DURING DEEP-FAT FRYING OF PRE-FRIED DEEP FROZEN FOOD WITH DIFFERENT SALT CONTENT

Changes of edible oil quality factors and formation of 3-monochloro-1,2-propanediol fatty acid esters (3-MCPD-FE) during deep-fat frying in four different experiments (control, salt, pork chop, and chicken liver) with high oleic sunflower oil were compared in this study. Based on the results of investigated oil quality parameters, which were free fatty acid (FFA), anisidine value (AV), UV extinction at 232 and 268 nm (E232 and E268, respectively), and total polar material (TPM), only a modest deterioration of the frying oil was observed. As we expected, the 3-MCPD-FE content in the control samples did not reach the limit of quantification (0.1 mg kg–1), while the table salt itself caused a slight increase. The results of pork chop and chicken liver experiments were not statistically different from each other, after the third frying circle 0.52 and 0.39 mg kg–1 3-MCPD-FE levels were reached, respectively. Based on these values, the human exposure estimation resulted in a low risk.

Quality Assessment of Oil Used for Frying of Potato Chips: In the Case of Wolkite University Community

Frying is an old and widely used method of cooking and processing food. Typically, a food is immersed in heated oil for a short duration in a process known as immersion-oil frying. Consumers tend to associate color with flavor, safety, storage time, nutrition, and level of satisfaction, due to the fact that color correlates well with physical, chemical, and sensorial evaluations of food quality. Indicators of poor oil quality include elevated FFA, low smoke point, change of color, low iodine value, peroxide value, total polar material, high foaming properties and increased viscosity. Deep frying and the use of recycled oil for many times is a commonly practiced in commercial and sometimes in domestic cooking processes. The way of this cooking method may create a lipid peroxidation product which brings harm to human health. Quality assessment of oil used for frying of potato chips in the case of Wolkite university community studied. The result of physicochemical properties of oil were investigated from sample selected randomly around Wolkite town and these are free fatty acid, peroxide value, smoking point and iodine value of recycled oils was higher than the recommended values. The strength of current evidence makes it reasonable to recommend complete avoidance of fried foods or at most infrequent to moderate fried food consumption within the context of an overall healthy dietary pattern around Wolkite town. Generally, the present study shows the recycled oil used were not as standards of FAO and also the people of fried food makers were not having awareness about the impacts of recycled oils.

Frying Oil Evaluation by a Portable Sensor Based on Dielectric Constant Measurement.

A portable capacitive sensor was designed to assess frying oil degradation by measuring the changes in electrical capacitance. An interdigital electrode (IDE) was designed to be implemented as the testing probe (as IDEs are resistive to parasitic capacitance), together with an adjacent capacitive chip Pcap01 and a further microprocessor STM32, which were used as the data-processing elements. Experimental results demonstrated that viscosity could be a useful frying oil quality indicator, and also proved a preliminary correlation between IDE capacitance and oils’ total polar materials. This implies that IDE capacitance could be a suitable metric for conveniently assessing frying oil degradation. The designed capacitance sensor is light in weight, cost effective, and has excellent potential for simple, inexpensive, on-the-spot testing of the current quality of frying oil.

A novel emitter: Sensing mechanical stimuli and monitoring total polar materials in frying oil

A novel multifunctional D-A type triphenylamine derivative (CPA-TPA) was designed and synthesized via Knoevenagel condensation reaction. It was found with distinct aggregation-induced enhanced emission (AEE) characteristics and solvatochromic performance. Interestingly, its crystals showed distinct luminescent responses to anisotropic grinding and isotropic compression. Upon grinding, its orange emission was changed into yellow fluorescence (blue-shift 17 nm from 592 nm), while the orange emission was changed into a red fluorescence upon 30 GPa pressure (red-shift 9 nm). Significantly, both the maximum emission wavelength and fluorescence intensity of the crystalline solid displayed nice linear relationships to pressure. Thus it offered a promising candidate for mechanical stimuli sensing in practical applications. The mechanism of its distinct MFC was discussed by PXRD, DSC and XRSD experiments. Furthermore, it was found that CPA-TPA presented a hypersensitive response to viscosity, so an efficient quantitative determination method for total polar materials (TPM) in frying oil was established.

Can the Image Processing Technique Be Potentially Used to Evaluate Quality of Frying Oil?

The objective of this study was to investigate the feasibility of a computer vision system (CVS) for assessing the contact angle of frying oil. The oil was used to fry carbohydrate- and protein-based foods for 40 h, and the oil was collected for measuring free fatty acids (FFA), peroxide value (PV), total polar materials (TPMs), and FOS reading (dielectric constant). The results showed that FFA linearly increased with frying time (R2 > 0.95) while the polynomial correlation between TPMs and FOS reading as a result of time was observed (R2 > 0.97). The contact angle obtained from CVS was highly correlated with all chemical qualities (R2 > 0.94), except PV. In addition, the contact angle models could be used to adequately predict FFA, TPMs, and FOS reading of frying oil (R2 > 0.91). This result suggested that the image processing technique through CVS could be an appropriate alternative to chemical analysis, especially for small- and medium-scale industrial frying.

PROFIL SENYAWA POLAR TIGA JENIS MINYAK GORENG SELAMA PENGGORENGAN TAHU DAN TEMPE

The quality of repeatedly used frying oil can be seen from its total polar material (TPM) content. This study aims to determine the influence of different types of oil with different degrees of unsaturation (coco-nut, palm, soybean oil) and foodstuffs with different characteristics (tofu and tempe) to the formation of the polar compounds in repeatedly used frying oil, based on the content of TPM, FFA, BI, FTIR and UV-Vis spectra. Chemical characterization of materials used was done in the first research stage. The second stage was the analysis of the polar compounds of the oil which was used for 3 hours/day for a dried of 15 hours. The results showed that the type of oil and food type affected the levels of TPM with increasing time of frying. The highest level of TPM 19.41±0.13% obtained from combination soybean frying oil-tempeh (15 hours). The FTIR spectrum of the polar fraction from the used frying oil showed a large absorption in area 3600-3200 cm-1 wavelength in which hydroxyl groups indicate the polarity of the frying oil. The rate of in-crease of FFA in all combinations of oil type-tempeh was faster than combination oil type-tofu. Coconut oil-tofu has a slower rate for FFA and browning index. The carbonyl compound in frying oil was showed from peak spectrum absorption at 420 nm.

Influence of flour type on physico-chemical characteristics during deep frying.

The study focuses on understanding the influence of nutrients on frying oil degradation as well as its role in oil uptake by the fried substrate. Raw substrates were prepared taking refined wheat flour (rich in carbohydrate), soy flour (rich in protein) and gram flour (with both in a definite proportion) which were subjected to frying in sunflower oil at 185-200°C. Analysis of the fried oil, substrate and fried product was carried out. Increase in acid value with respect to the composition of the flour was not significant. Higher rate of oxidation and peroxide value were observed in the oil used for Gram flour snacks, which could be due to significant amounts of sodium and potassium salts. Fried oil with soy flour based snack showed higher total polar material% which could be due to accelerated oxidation. Oil absorption was promoted by starch and gluten and controlled by protein and insoluble fiber. Oil absorbed by refined-wheat flour and soy flour based snack were 30% and 9.33%. Gram flour-based snack absorbed 4.52% oil with superior oil quality comparatively.

Impact of novel far‐infrared frying technique on quality aspects of chicken nuggets and frying medium

The impact of far‐infrared and conventional heaters on heat distribution and physicochemical qualities of chicken nuggets and frying medium were investigated. For chicken nuggets, moisture content, fat content, color (L*, a*, and b*), and texture characteristics were determined, while free fatty acid (FFA), peroxide value (PV), total polar materials (TPMs), and color were used to measure the quality of frying oil. A higher heating rate and more uniform heat distribution were observed in the far‐infrared frying. Physicochemical qualities of chicken nugget were not significantly influenced by type of heater, except the fat content in the crust was significantly higher (p < 0.05) in far‐infrared fried samples. The FFA, TPM, and color values of frying oil were better in far‐infrared frying. Far‐infrared frying can be used for about 56 and 115 more cycles than conventional frying when using FFA of 0.8% and TPM of 25%, respectively as an indicator to discard the oil. PRACTICAL APPLICATION: These results present a novel technology for using far‐infrared radiation in deep‐fat frying process. The far‐infrared radiation provides a way of uniform heating of food. In addition, it therefore shortens frying time, saves energy, and prolong the shelf life of frying medium.

Investigation of cooking oil quality at fast food restaurants in Mashhad City

Aims: Deep frying of foods at high temperatures results in an increase in the unique sensorial properties of fried food including fried flavor, golden brown color, and crispy texture, which ultimately leads to changes in the physical and chemical properties of the oil. This study was conducted to evaluate the quality of oils used in 60 centers of fast food distribution in Mashhad city. Materials and Methods: A validated questionnaire based on the instruction from the Ministry of Health and Medical Sciences was used to collect the data and to investigate the health status of the places and foods. Total polar material (TPM), temperature, and acidity of the oil were measured using oil test portable device (DOM-24 model) while the peroxide value (PV) was measured by iodometry method. The data were analyzed by SPSS software V.16 via statistical tests including t-test, ANOVA, and Chi-squared tests.Results: The mean values of TPM, acidity and PV in the studied oils were 31.8 ± 7.2 %, 3.7 ± 0.8, 4.7 ± 6.7 meq/kg, respectively. There was a significant relationship between TPM value with acidity, temperature and duration of oil use based on Pearson correlation test (P > 0.005). Furthermore, there was a significant relationship between the PV and area, the type of oil, and sanitation of instruments. Conclusion: The levels of hydrogen peroxide, polarity, and acidity of oils in fast food shops were higher than the guideline values. We recommend that health inspectors systematically monitor the oils fried in these centers.

Impact of Purslane (Portulaca oleracea L.) Leaves Extract to Enhance the Anti-oxidant Potential of Edible Oils during Heating.

The present work deals/ reveals with the effect of purslane leaves extract on the stability of soybean oil during heating and the acceptability of oil after preparation of poori (an Indian fried bread) by frying and its sensory evaluation. The ethanolic purslane leaves extract was blended with soybean oil at three different concentrations such as, 500, 1000 and 1500 ppm (T1, T2 and T3) and compared with control. The sample added with 100 ppm TBHQ was used as a positive control. Assessment of antioxidant activity of the ethanolic extract of purslane leaves was carried out by the estimation of total phenolic content, loss of β-carotene and antioxidant activity. The heating (173±2°C for 24 h; 8 h heating cycles per day) performance of soybean oil incorporated with purslane leaves extract was evaluated in terms of peroxide value, free fatty acid, total polar material and fatty acid composition. The thermal stability of the oils was evaluated using differential scanning calorimeter. The poori was prepared to check the acceptability of the oil. Results suggest that leaves extract of purslane (1500 ppm) may be used for obtaining reasonable thermal stability of soybean oil with acceptable sensory characteristics of the product. Although TBHQ showed almost similar thermal stability with leaves extract of purslane (1500 ppm), natural anti-oxidant is more preferred over synthetic anti-oxidant.

Variable selection for the determination of total polar materials in fried oils by near infrared spectroscopy

Total polar materials (TPM) content is considered as the best indicator and the most common parameter to check the quality of deep-frying oils. The development of simpler and quicker analytical techniques than the available methods to monitor oil quality in restaurants and fried food outlets is an important topic related to the human health. This paper reports a comparison of the variable selection of near infrared (NIR) spectra by multiple linear regression (MLR-NIR) with partial least squares (PLS-NIR) models for the quantification of TPM in fried vegetable oils. The use of PLS-NIR offers an alternative in laboratory bench equipment for the determination of TPM in oils employed for frying different kinds of foods with relative prediction errors of 6.5%, a coefficient of determination for prediction of 0.99 and a residual predictive deviation (RPD) of 9.2 when selected wavenumber intervals were employed. MLR-NIR allows the selection of a reduced number of wavenumber in order to develop low cost instruments to evaluate the frying oil quality. Based on the NIR signals at four wavenumbers, the relative prediction error was 12.1%, the coefficient of determination for prediction was 0.96 and the RPD was 5.0.

Oxidation degree of soybean oil at induction time point under Rancimat test condition: Theoretical derivation and experimental observation

Indices including conductivity, short-chain carboxylic acids, total polar material, acid value, peroxide value and fatty acid composition in water or oil were monitored during Rancimat test of soybean oil from 90 °C to 120 °C. Formic, acetic, propionic and butyric acids in water were detected by ion chromatography. The results showed that all indices had two-stage oxidation rates of initiation (ki) and propagation (kp) at each temperature. Induction period (IP) computed from conductivity and other indices were well correlated (R2 = 0.9980–0.9999). According to the Arrhenius model and empirical equation, ki increased exponentially with temperature (T) while IP decreased exponentially with T. Oxidation degree of oil at induction time point IP*ki was found to be independent of heating time and temperature. The transition between two models was theoretically derived and proved by H NMR. Evaluation of IP*ki may provide a new route to correlate Rancimat data with shelf life of edible oil.

Effect of frying oil degradation on surface tension and wettability

Frying oil degrades via exposure to heat, oxygen and water resulting in the formation of volatile and non-volatile products, which act as surface active substances and change heat and mass transfer rates. Effects of oil degradation during frying were quantified by measuring viscosity, surface tension, and static and dynamic contact angles of fresh oil (Total polar materials, TPM 3–4%) and used oils (TPM 10–20%). Oil viscosity decreased exponentially with increasing temperature (40–200 °C). Used oil viscosity was higher than fresh oil at room temperature; no significant difference was recorded above 60 °C. Pendant drop technique was used to measure air-oil (24–200 °C) and steam-oil (100–200 °C) surface tension of all oil samples. Surface tension decreased linearly as temperature increased. There was no effect of surrounding medium (air or steam) or oil quality on surface tension. Surface tension was time independent for both oils, as observed with a 5 h measurement using rising-bubble technique. Static contact angles of all used oils were lower than fresh oil, indicating increased wettability of used oil, which can affect amount of oil absorbed during frying and post-fry cooling. Hysteresis of used oil (13°–15°) was lower than fresh oil (18°), which can impact drainage during post-fry cooling.

At‐line monitoring of industrial frying processes using ATR‐FTIR‐PLS method

AbstractThis study investigated the application of infrared spectroscopy with multivariate calibration methods for at‐line monitoring of the degradation of soybean oil in industrial frying processes by determining when the acidity index and total polar materials (TPM). The infrared spectra (650–3,200 cm−1) were acquired using the attenuated total reflection accessory (ATR‐FTIR), with a resolution of 4 cm−1, and 16 scans. Partial least‐squares regression (PLS) models were evaluated for individual and simultaneous determination, and results were compared with reference methods. The individual calibration model showed standard error of prediction values of 0.09% (w/w) and 1.6% (w/w) for the acidity index and TPM, respectively. The simultaneous determination of the acidity index and TPM showed SEP values of 0.17% (w/w) and 1.6% (w/w), respectively. The results demonstrate that infrared spectroscopy combined with multivariate calibration techniques can be servant used in routine soybean oil quality control in industrial frying processes.Practical applicationsFoods prepared by the frying process are strongly influenced by the oil used in the process, since the product tends to absorb part of the oil during its cooking. This oil when used for a long period and exposed to high temperatures, end up suffering oxidation reactions, and can greatly reduce your shelf life. In this way the industries that use these processes for the manufacture of their products, apply a series of chemical analyzes in order to validate the quality of the oil used, these analyzes use a high amount of solvents and time. As an alternative to the use of these traditional analyzes, methods have been developed through the use of infrared spectroscopy combined with multivariate analysis tools, for the creation of partial least squares calibration models for the prediction of quality parameters of oils used in frying.

Regeneration of Used Frying Oils by Selected Metal–Organic Frameworks as Adsorbents

AbstractThe aim of this study was to utilize seven synthesized metal–organic frameworks (MOF) and three natural clays as adsorbents in regenerating used frying oil. First, surface and pore properties, and morphologies of the adsorbents were determined, and used frying oil was treated at 0.1% addition (w/w) level. Then, physicochemical properties, mineral, and fatty‐acid compositions of oil were analyzed. Finally, a recycling study was performed over five cycles with three selected adsorbents. Although there were only small improvements in oil color values, oil turbidity was significantly reduced with the adsorbents. Free fatty acidity values were reduced by 50.6% and 42.2% with Ti‐MOF and zeolitic‐MOF (ZIF‐8‐MOF) adsorbent treatments. Likewise, peroxide value reductions ranged from 43.6% with the Ti‐MOF to 18.1% with natural zeolite. Reductions in the total polar materials (TPM) were the highest (42.5%) with aluminum‐MOF (Al‐MOF) followed by the ZIF‐8‐MOF (40.4%). Contents of aluminum, zinc, phosphorous, chromium, magnesium, and potassium were measured in the control and adsorbent‐treated oil samples, and it was found that there was no leakage of minerals from the MOF into the oil, but rather some reductions due to adsorption. Furthermore, recycling studies with Ti‐MOF, Cr‐MOF, and sepiolite showed that the MOF can be used up to five times with only small activity losses compared with sepiolite. Overall, this study demonstrated the great potential of the MOF as adsorbents for frying oil regeneration, and pointed out that more research needed to design and synthesize new MOF structures for applying in the edible oil industry.

Correlation of the Solid‐Fat Content in Vegetable Oils with Other Parameters during Thermal Oxidation

AbstractCorrelations of the solid‐fat content (SFC) with oxidative parameters were determined in three vegetable oils including corn, soybean, and palm oils, during thermal oxidation at 150°C. As the oxidation time increased, SFC and oxidation parameters, including conjugated dienoic acid (CDA) value, p‐anisidine value (p‐AV), acid value, and total polar materials (TPM), increased at different rates in all oils. Although corn and soybean oil underwent higher rates of lipid oxidation than palm oil, SFC changes in palm oil were observed at higher rates than those in corn and soybean oils. Palm oil showed a high correlation of SFC against p‐AV and TPM compared with corn and soybean oils. Soybean oil showed a higher correlation of SFC and oxidation parameters than corn oil except acid values. SFC could be useful to determine secondary lipid oxidation products and the level of TPM in oxidized vegetable oils.

Cellulose acetate and adsorbents supported on cellulose fiber extracted from waxy corn husks for improving shelf life of frying oil

The efficacy of cellulose paper consolidated with cellulose acetate and mixed adsorbents (bentonite: activated clay: celite = 37.5: 50: 12.5 g with 1 g citric acid/100 g mixed adsorbents) on the physico-chemical properties of oil was evaluated during deep-fat frying of chicken nuggets for 7 days. Cellulose fiber and cellulose acetate were produced from waxy corn husks. Using adsorbents supported on cellulose fiber with or without cellulose acetate resulted in lower poly-unsaturated fatty acids (PUFAs), trans-fatty acid, free fatty acid (FFA), peroxide value (PV), and total polar materials (TPMs) compared with results from commercial filter paper (control). The L*, a*, and b* changes of treated oils were better than in control. Limiting the polarity in cellulose acetate might influence TPMs reduction but was more effective in overall quality improvement. The PUFAs, total trans-fatty acid, FFA, PV, and TPMs decreased by 1.8, 7.4, 37.0, 133.3, and 20.5%, respectively when compared with control. Therefore, the use of cellulose paper and cellulose acetate obtained from corn husks was found to significantly lengthen the life cycle of frying oil.

Evolution of Frying Oil Quality Using Fourier Transform Near-Infrared (FT-NIR) Spectroscopy.

This study assesses the capacity of a Fourier transform near-infrared (FT-NIR) spectrometer operating in the range 4500-12 000 cm-1 (833.33-2222.22 nm) to provide quantitative predictions for the parameters of acidity (AV), p-anisidine (pAV), total polar materials (TPM), peroxide value (PV), and oxidative stability index (OSI). 562 samples of frying oil were analyzed from 14 distinct types of oil. The calibrations obtained accounted for 96%, 95%, 99%, 92%, and 91% of the AV, pAV, TPM, PV, and OSI variations in the study set and the similarity between the standard error of laboratory (RMSEP) values and the reference method errors (RMSEL), enabling the authors to conclude that NIR technology has the capacity to replace traditional methods in thermo-oxidative degradation studies in frying oils.

Formation of Ester Bound 2‐ and 3‐MCPD and Esterified Glycidol in Deep‐Fried and Pickled Herring Products

In Germany, the best‐selling fish products are canned and marinated fish products including deep‐fried and pickled herring products. During processing, pre‐salted herring fillets are breaded, deep‐fried, and covered by an aqueous marinade containing vinegar and sodium chloride. For shelf‐life extension, the packaged fish can be pasteurized. Due to the co‐occurrence of sodium chloride and glycerol derivatives such as tri‐ or diacylglycerides, the deep‐frying and pasteurization procedure may lead to the formation of fatty acid esters of 2‐monochloropropane‐1,3‐diol and 3‐monochloropropane‐1,2‐diol (MCPD‐E) and of glycidol (G‐E). Various product as well as process dependent parameters on the formation of MCPD‐E and G‐E in deep‐fried and pickled herring products are studied. The frying‐life of the oil has the strongest effect on the formation of MCPD‐E in herring products. 3‐MCPD‐E contents increases from 341 ± 48 to 1133 ± 194 μg kg−1 lipid in the products after 9 days frying‐life of the oil. Moreover, it is shown that the major proportion of MCPD‐E in these products originates from the deep‐frying oil. The analyses of total polar material and spectrophotometric measurement of the absorption at 420 nm of the deep‐frying oil are identified as suitable screening methods for estimating MCPD‐E contents in deep‐fried and pickled herring products.Practical Applications: Canned and marinated fish products are the best‐selling fish products (28% market share) on the German market. Up to now, no studies regarding the deep‐frying procedure of pickled herring products are published. Deep‐frying has shown to be a process leading to MCPD‐E and G‐E in fish products mainly affected by intake of deep‐frying oil. The knowledge about the effect of process and product based parameters on the formation of MCPD‐E and G‐E in deep‐fried and pickled herring products may be of particular interest for the fish‐processing industry in order to manage that quality issue. Moreover, methods for the assessment of the deep‐frying oil quality such as the analysis of the total polar material (TPM) and the spectrophotometric measurement of the absorption at 420 nm deemed suitable screening methods for estimating the MCPD‐E contents in deep‐fried and pickled herring products.Deep‐frying of pickled herring products leads to the formation of MCPD‐E and G‐E, mainly affected by intake of deep‐frying oil and the frying‐life of the oil. Methods for the assessment of the frying oil quality, such as the analysis of TPM and the spectrophotometric measurement of the absorption, are suitable screening methods for estimating the MCPD‐E contents in deep‐fried fish products.

The critical micelle concentration of lecithin in bulk oils and medium chain triacylglycerol is influenced by moisture content and total polar materials

Effects of different moisture contents and oxidised compounds on the critical micelle concentration (CMC) of lecithin were determined in bulk oils and in medium-chain triacylglycerols (MCT). CMC of lecithin in MCT was significantly higher than that in other vegetable oils including olive, soybean, corn, and rapeseed oils (p < 0.05). Presence of moisture significantly affected the CMC of lecithin in MCT (p < 0.05). CMC of lecithin was high when the moisture content was below 900 ppm, whereas at a moisture content of 1000 ppm, CMC of lecithin decreased significantly (p < 0.05), and then started to increase. Addition of total polar materials (TPM), which are oxidation products, at 3 and 5% concentrations, decreased CMC of lecithin significantly (p < 0.05) in MCT, compared to when 0, 1, and 1.5% of TPM was added to MCT. As the degree of oxidation increased in corn oil, CMC of lecithin gradually decreased. Additionally, under different moisture contents, corn oils showed a similar pattern of CMC of lecithin in MCT, whereas oxidised corn oil had a little lower CMC of lecithin than unoxidised corn oil. The results clearly showed that the concentration of lecithin for the formation of micelles is greatly influenced by the presence of oxidation products and the moisture content in bulk oils.