Determination of saturated fat, unsaturated fat, and trans fat in commercial instant noodles based on the analysis of fatty acid composition by gas chromatography

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In this study, we used the reliable GC-FID/MS technique to analyze the methyl ester derivatives of 37 different kinds of fatty acids. The results showed that high saturated fat concentration in all samples was mostly palmitic acid, whereas the low unsaturated fatty acid content in the cis form was primarily oleic acid and linoleic acid. The amount of monounsaturated and polyunsaturated fats is quite low.

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Nội dung Text: Determination of saturated fat, unsaturated fat, and trans fat in commercial instant noodles based on the analysis of fatty acid composition by gas chromatography

Cite this paper: Vietnam J. Chem., 2023, 61(S2), 143-148 Research Article DOI: 10.1002/vjch.202300099 Determination of saturated fat, unsaturated fat, and trans fat in commercial instant noodles based on the analysis of fatty acid composition by gas chromatography Nguyen Khanh Hung1,2, Nguyen Phuong Trang1,2, Nguyen Huy Du1,2,3,* 1 Faculty of Chemistry, University of Science, 227 Nguyen Van Cu Road, District 5, Ho Chi Minh City 70000, Viet Nam 2 Vietnam National University of Ho Chi Minh City, Vo Truong Toan Road, Linh Trung Ward, Thu Duc City, Ho Chi Minh City 70000, Viet Nam 3 Central Laboratory of Analysis, University of Science, 227 Nguyen Van Cu Road, District 5, Ho Chi Minh City 70000, Viet Nam Submitted February 23, 2023; Revised May 7, 2023; Accepted May 30, 2023 Abstract In the food processing sector, it is crucial to identify the composition and fat content of items that have undergone heat-processing. The total fat content is the primary factor used to determine the fat content of instant noodle products. As a result, a technique must be developed to identify fat content by determination of fatty acid composition, particularly trans fatty acids. In this study, we used the reliable GC-FID/MS technique to analyze the methyl ester derivatives of 37 different kinds of fatty acids. The results showed that high saturated fat concentration in all samples was mostly palmitic acid, whereas the low unsaturated fatty acid content in the cis form was primarily oleic acid and linoleic acid. The amount of monounsaturated and polyunsaturated fats is quite low. Trans fat level was almost non-existent in all samples. The amounts of palmitic acid and oleic acid in the samples ranged from 4.10% to 12.84% and 2.62% to 7.65%, respectively, as did linoleic acid and stearic acid. Monounsaturated and polyunsaturated fatty acid concentration ranged from 2.62% to 7.82% and 0.52 to 1.81%, respectively. The proportion of polyunsaturated fat to saturated fat was quite low. Therefore, it is essential to have procedures in place to keep an eye on the saturated fatty acid level, which has a negative impact on consumers' health. The findings of experimental research demonstrated that trans fatty acids were not present in instant noodle products. It revealed that the food processing sector has advanced favorably and catered to the demands of both the domestic and international markets. Keywords. Instant noodles, trans fat, fatty acids composition, GC-FID/MS, FAMEs. 1. INTRODUCTION composition as well as trans fats in instant noodles in Vietnam market is still very limited.[5] Additionally, Instant noodles are taken into account not only by the composition of trans fatty acids has not been high demand, but also by many potential health clearly addressed, and the existing regulation on fat issues.[1-3] Concerns on the presence of trans fat, one content focuses mostly on the total fat content, in of the causes considered to relate to cardiovascular which the fat composition is primarily expressed disease, have been raised due to the large amount of through the fatty acid content. In order to locate and fat utilized in the process.[2,5] Low-melting fat has provide a adequate assessment of the presence of been widely applied in the food processing sector, trans fat in the instant noodle products, it is important especially in instant noodles because it contributes to to give an appropriate analytical procedure and data improved texture, color and stability.[6] Fats applied on fatty acid profile and trans fatty acid composition. in food are mainly derived from plants through partial In this study, a reliable analytical GC-MS method hydrogenation of unsaturated fats and would be developed and validated, to determine fatty interesterification, which can notably form trans fats acid composition, as well as confirm the presence of during partial hydrogenation of unsaturated fats and trans fat in instant noodles including: Extraction of also during processing when heated to high fat, high yield derivatization of methyl esters with temperatures.[7] Currently, the study on fatty acid both acid and base catalysts. 143 Wiley Online Library © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH
25728288, 2023, S2, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300099 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry Nguyen Huy Du et al. 2. MATERIALS AND METHODS thermostatic bath. A mixture of 50 mL diethyl ether and petroleum ether (1:1, v/v) was added to the 2.1. Aparatus and chemicals reaction flask, tightly closed. The extraction flask was then shaken for 15 min and allowed to separate for Gas chromatography system from Shimadzu includes approximately 10 min. The upper solvent layer was injector, oven, and mass detector. Analysis capillary anhydrous and repeat the same extraction process 2 column was Agilent J&W DB-FastFAME, 30 m  more times until the fatty acids were gone. 0.25 mm  0.25 µm (p/n G3903-63011). Thermostatic bath (Fisher Scientific), Vortex shaker 2.5. Methyl esterification of fatty acid (Velp Scientific, Germany), Elma S180H ultrasonic cleaner (Elma, Germany), 5 digit digital balance The solution after evaporation was subjected to (Satorius, Germany), magnetic stirrer with hot plate methyl esterification with 10 mL of 0.5 M NaOH in (IKA, Vietnam). methanol, heated under reflux for 30 min, and cooled Helium 99.999% was used as carrier gas, n-heptane, to room temperature. Add 5 mL of BF3 20% in n-hexane GC-MS Grade (Merck, Germany), methanol and 10 mL of methanol, heat for a further hydrochloric acid (VWR, UK), sodium hydroxide 20 minutes, lift and cool to room temperature. Then, (Merck, Germany). add 10 mL of n-heptane and 5 mL of saturated NaCl. 1 mL of n-heptane (top solution) to the vial or dilute 2.2. Sampling the sample as neede prior to analyze by GC-MS gas chromatograpy. Samples of instant noodles were purchased at supermarkets and convenience stores. The mark 2.6. Optimal GC analysis condition and pattern was coded from SA01 to SA30. Along with quantification of FAMEs imported goods, the samples chosen include instant noodles in Vietnam and international manufacturers. The FAMEs were resolved by using GC-MS from To carry out storage and analysis operations, samples Shimadzhu. A polar capillary column Agilent J&W are homogenized and separated into coding DB-FastFAME (30 m  0.25 mm), 0.25 µm film subsamples corresponding to each product. thickness (Agilent, USA) was used. The temperature of injector, source, and the interface was set at 250, 2.3. Total lipid extraction 230 and 250oC, respectively. Helium was used as a gas carrier with a flow rate of 1.2 mL min-1; the The crude fat extraction procedure was carried out in sample (1 µL) was injected in a split ratio of 1:2. The accordance with ISO 734:2015 as follows: 1 g of the oven temperature was programmed from an initial sample was placed in a 100 mL flask containing 20 temperature of 50oC (hold 0.5 min) ramp to 194oC mL of n-hexane and soaked for at least 4 h or (hold 3.5 min) at rate of 30oC min-1. The temperature overnight. Heat the mixture in reflux condition for 4 was then ramped to 240oC at rate of 5oC min-1. h and cool down to room temperature. The extraction solvent for the sample was collected and filtered 2.7. FAMEs identification through a glass funnel containing 5 g of anhydrous Na2SO4. The sample was extracted continuously 2 Chromatographic peaks were identified by more times in 1 hour with 20 mL of n-hexane for each comparison with chromatogram of fatty acid methyl subsequent extraction. Evaporate to recover the ester standardsand confirmed relying on the remaining n-hexane residue and make up to 5 mL comparison of their mass spectrum with those of with n-hexane. NIST 2.2 library data. After being identified, FAMEs would be annotated in the form of 2.4. The hydrolyzation of total fat and extraction [A]:[B] cis- [C] trans- [T] of fatty acid where [A] is the number of carbons (including the carboxyl group), [B] is the number of double bonds, Crude fat was hydrolyzed in accordance with AOAC [C] is the list of positions of the cis double bonds, [T] 996.06 standard procedure.[8] The fatty acid is the position of the trans double bond. hydrolysis and extraction procedure was performed as follows: 1 mL of the extracted sample in section 1 3. RESULTS AND DISCUSSION was added to a flask and dried by a stream of nitrogen gas. 2 mL ethanol and 10 mL of 8 M HCl were then 3.1. Fatty acid methyl esters (FAMEs) added to the flask and heated at 80°C for 40 min in a identification © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 144
25728288, 2023, S2, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300099 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry Determination of saturated fat, unsaturated fat, and… All of the fatty acid derivatives, including the cis and samples, for saturated fatty acids, palmitic acid trans isomers, were found to effectively separate all accounted for the highest content present in all compounds on the chromatogram. The solvent delay samples. Palmitic acid content was from 4.10 to was set at 4.0 minutes to avoid recording the solvent 12.84%, stearic acid was followed, with the content signal as it passed through the detector, however from 0.41 to 1.21%. For unsaturated fatty acids, oleic because heptane and C4:0 have similar boiling points, acid accounts for a significant amount, from 2.62 to the C4:0 peak was not recorded in the chromatogram. 7.75%, linoleic acid was followed, which accounted However, since C4:0 was not present in the sample, for 0.46 to 0.72%. Many previous studies have shown improving the solvent delay time to record C4:0 does that saturated fatty acids with long carbon chains not necessary go beyond assuring the safety of the from C12:0 to C16:0 are the causative agents of filament. atherosclerosis, whereas oleic acid and From the experimental analysis results of FAMEs polyunsaturation fatty acids has a lipid-lowering identification based on retention time compared with effect in the blood. standard and MS mass spectroscopy data, the elution The contents of saturated, monounsaturated and order of FAMEs depends mainly on boiling point, polyunsaturated fatty acids were shown in figure 2, dipole force and diffusion interaction with the with SFA accounting for the majority of the content cyanopropyl stationary phase of the chromatographic in each sample. Sample SA17 had the greatest column. We found that the cyanopropyl stationary concentration of saturated fatty acids, 14.40%, phase was strongly polar, and that the diffusion and followed by samples SA26 and SA06, 13.28 and dipole interactions of the monounsaturated and 12.01%, respectively. Saturated fatty acid polyunsaturated FAMEs were relatively strong so concentrations in the samples varied from 4.72 to they are eluted after saturated FAMEs of the same 14.4%. The samples’ monounsaturated fatty acid number carbon atom. Additionally, we discovered contents ranged from 2.62 to 7.82%, with sample that the cis-isomers exhibited greater diffusion and SA11 having the greatest concentration (which was dipole interactions than the trans-isomers for FAMEs 7.82%) and sample SA21 having the lowest with geometric isomers like C18:1n9 and C18:2n6, concentration (which was 2.62%). Oleic acid makes which led to the trans-isomers being eluted from the up a significant portion of monounsaturated fatty chromatographic column before the cis isomer. acids, which are mostly found in the cis form. Previous studies have also demonstrated that the According to the recommendations of the UK number of double bonds and the structure of the fat, Department of Health, the ratio of polyunsaturated especially the double bond site, influence the fatty acids and saturated fatty acids content is 0.45.[4] retention time of FAMEs in the chromatogram. We In this study, the ratio of polyunsaturated fatty acids might deduce from the analysis’s findings that the to saturated fatty acids in instant noodles samples FAMEs include a significant number of double ranged from 0.04 to 0.17 which is much lower than bonds, and that the further away a double bond is recommended. Low levels of polyunsaturated fatty from the ester functional group, the greater its dipole acids ranging from 0.52 to 1.81% were found in and diffusion interactions are, and the later it is eluted sample SA26 and sample SA11, respectively. The in the chromatogram. content of polyunsaturated fatty acids indicated the use of solid fats obtained by the hydrogenation of 3.2. Fatty acid composition of instant noodle vegetable oils. Polyunsaturated fatty acids are generally good for health such as regulating lipid Results of fat analysis content in instant noodle levels in the heart and in the immune system. Figure 1: Chromatograms of (A) 37 FAMEs standard (B) fatty acid composition of instant noodle © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 145
25728288, 2023, S2, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300099 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry Nguyen Huy Du et al. Figure 2: Content of fatty acid groups The chromatogram for the study showed that Trans fatty acids including C18:1, C18:2 and C18:2 there was no peak between the signals of C18:0 and isomers were present in most of the analyzed biscuit C18:1n9-cis and between C18:2n6-cis (see figure 1), samples, accounting for 80% of the total trans fatty and that the signals in these two ranges were, in fact, acids.[5] The total C18:2-trans fatty acid monomers C18:1n9-trans and C18:2n6-trans, respectively. This including (cis-trans and trans-cis) accounted for indicated that trans fatty acids were not present. Tuan 0.07-5.48% of total fat content, which was the most et al. determined the content of fatty acids in samples common group of polyunsaturated trans fatty acids. of biscuit produced domestically showed the content The C18:1n9 trans isomer was detected at of trans fatty acids ranged from 0.00% to 7.16% of concentrations as low as 0.05 to 1.53% of the total fat total fatty acids, with an average value of 0.54%. content. Table 1: Fatty acid composition of selected Vietnamese instant noodles (SA01-SA10) Content (%) No FAMEs SA01 SA02 SA03 SA04 SA05 SA06 SA07 SA08 SA09 SA10 1 C12:0 0.005 0.014 0.038 nd 0.015 0.005 0.004 nd 0.023 0.038 2 C14:0 0.30 0.27 0.27 0.27 0.35 0.32 0.33 0.26 0.29 0.35 3 C16:0 7.65 6.86 7.34 7.59 8.46 10.59 7.41 9.05 7.07 8.47 4 C16:1 0.021 nd nd nd nd nd nd nd nd nd 5 C18:0 0.88 0.83 0.82 0.81 0.93 0.95 0.96 0.77 0.82 0.98 6 C18:1trans nd nd nd nd nd nd nd nd nd nd 7 C18:1cis 4.43 5.39 4.19 5.36 4.90 6.05 4.09 5.09 4.66 6.01 8 C18:2trans nd nd nd nd nd nd nd nd nd nd 9 C18:2cis 1.10 1.26 1.31 1.00 1.09 1.22 1.21 1.01 1.25 1.46 10 C18:3n3 0.077 0.073 0.000 0.075 0.032 nd 0.070 0.073 0.076 0.081 11 C20:0 0.072 0.081 0.073 0.079 0.35 0.092 0.097 0.066 0.092 0.091 12 C20:1 nd nd 0.057 0.065 nd 0.059 nd nd nd nd 13 C22:0 0.027 nd 0.023 0.023 nd 0.024 nd nd 0.024 nd 14 C23:0 nd nd nd 0.12 nd nd nd nd nd nd 15 C24:0 0.20 0.20 nd nd nd nd 0.20 nd nd nd Total fat (%) 14.76 14.98 14.12 15.39 16.12 19.34 14.36 16.35 14.31 17.45 SFA (%) 9.14 8.25 8.57 8.89 10.10 12.01 8.99 10.18 8.32 9.90 MUFA (%) 4.45 5.39 4.24 5.43 4.90 6.11 4.09 5.09 4.66 6.01 PUFA 1.17 1.34 1.31 1.07 1.12 1.22 1.28 1.08 1.33 1.54 PUFA/SFA 0.13 0.16 0.15 0.12 0.13 0.10 0.14 0.11 0.16 0.17 SFA: Saturated fatty acids. MUFA: Monounsaturated fatty acids. PUFA: Polyunsaturated fatty acids. nd: Non-detected. © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 146
25728288, 2023, S2, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300099 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry Determination of saturated fat, unsaturated fat, and… Table 2: Fatty acid composition of selected Vietnamese instant noodles (SA11-SA20) Content (%) No FAMEs SA11 SA12 SA13 SA14 SA15 SA16 SA17 SA18 SA19 SA20 1 C12:0 0.020 nd nd 0.015 0.011 nd 0.008 nd nd 0.02 2 C14:0 0.43 0.23 0.27 0.31 0.30 0.24 0.34 0.30 0.28 0.34 3 C16:0 11.90 6.76 9.76 8.41 7.49 6.71 12.84 8.61 8.94 9.54 4 C18:0 1.69 0.68 0.81 0.94 0.95 0.75 1.05 0.95 0.77 1.07 5 C18:1trans nd nd nd nd nd nd nd nd nd nd 6 C18:1cis 7.75 3.47 5.73 6.12 4.34 4.49 7.52 4.90 5.21 5.73 7 C18:2trans nd nd nd nd nd nd nd nd nd nd 8 C18:2cis 1.72 0.80 0.98 1.42 1.10 1.14 1.27 1.03 1.01 1.23 9 C18:3n3 0.095 nd 0.080 0.080 0.057 0.072 nd nd 0.079 0.066 10 C20:0 0.16 0.061 0.080 0.102 0.081 0.076 0.109 0.090 0.080 0.10 11 C20:1 0.070 nd 0.053 0.052 0.055 nd nd nd nd 0.043 12 C22:0 0.033 0.032 nd nd 0.026 nd nd nd nd nd 13 C24:0 0.21 nd nd 0.20 nd nd nd nd nd nd Total fat (%) 24.02 12.03 17.74 17.69 14.35 13.47 23.19 15.88 16.40 18.15 SFA (%) 14.39 7.76 10.89 10.01 8.83 7.77 14.40 9.95 10.10 11.10 MUFA (%) 7.82 3.47 5.79 6.18 4.37 4.49 7.52 4.90 5.21 5.75 PUFA 1.81 0.80 1.06 1.50 1.15 1.21 1.27 1.03 1.09 1.30 PUFA/SFA 0.13 0.10 0.10 0.15 0.12 0.16 0.09 0.10 0.11 0.12 SFA: Saturated fatty acids. MUFA: Monounsaturated fatty acids. PUFA: Polyunsaturated fatty acids. nd: Non-detected. Table 3: Fatty acid composition of selected Vietnamese instant noodles (SA21-SA30) Content (%) No FAMEs SA21 SA22 SA23 SA24 SA25 SA26 SA27 SA28 SA29 SA30 1 C12:0 nd 0.024 0.005 0.018 0.019 0.018 0.0030 0.0018 0.0055 0.023 2 C14:0 0.15 0.25 0.26 0.29 0.30 0.41 0.30 0.30 0.33 0.39 3 C16:0 4.10 7.79 7.67 8.88 7.70 11.35 8.13 9.34 9.46 9.30 4 C18:0 0.41 0.76 0.82 0.89 0.96 1.21 0.85 0.85 1.07 1.18 5 C18:1trans nd nd nd nd nd nd nd nd nd nd 6 C18:1cis 2.62 5.63 5.21 6.50 5.76 5.92 3.91 4.52 5.41 5.37 7 C18:2trans nd nd nd nd nd nd nd nd nd nd 8 C18:2cis 0.62 1.10 1.26 1.35 1.41 0.46 0.92 0.95 1.22 1.28 9 C18:3n6 nd nd nd nd nd nd nd nd nd nd 10 C18:3n3 nd nd 0.076 0.079 0.075 0.069 0.068 0.072 0.087 0.078 11 C20:0 0.057 0.081 0.091 0.096 0.088 0.12 0.081 0.080 0.11 0.11 12 C20:1 nd 0.044 0.049 0.050 nd 0.049 nd nd nd 0.060 13 C22:0 nd 0.023 nd nd 0.023 0.024 nd nd 0.026 nd 14 C24:0 nd 0.20 nd nd nd 0.20 nd nd 0.20 nd Total fat (%) 7.95 15.89 15.42 18.18 16.30 19.76 14.26 16.14 17.91 17.75 SFA (%) 4.72 9.12 8.84 10.2 9.06 13.28 9.36 10.6 11.19 11.0 MUFA (%) 2.62 5.67 5.25 6.55 5.76 5.97 3.91 4.52 5.41 5.40 PUFA 0.62 1.10 1.33 1.43 1.48 0.52 0.99 1.02 1.31 1.35 PUFA/SFA 0.13 0.12 0.15 0.14 0.17 0.04 0.11 0.10 0.12 0.12 SFA: Saturated fatty acids. MUFA: Monounsaturated fatty acids. PUFA: Polyunsaturated fatty acids. nd: Non-detected. 4. CONCLUSION food processing sector is increasingly developing, following scientific recommendations on health In our study on instant noodles samples, no trans fatty safety for consumers to meet global requirements and acids were detected. This shows that the domestic changing production processes to significantly reduce © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 147
25728288, 2023, S2, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300099 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Vietnam Journal of Chemistry Nguyen Huy Du et al. the presence of trans fatty acids. The difference in and public health concerns of instant noodles as total fatty acids, saturated fatty acids and unsaturated influenced by raw materials and processing fatty acids in the samples of instant noodles can be technology, Food Rev. Int., 2020, 36(3), 276. explained by the different ingredients used by the 2. I. A. Charles, A. J. Ogbolosingha, I. U. Afia. Health risk assessment of instant noodles commonly manufacturers in terms of quality, content, processing consumed in Port Harcourt, Nigeria, Environ. Sci. time, temperature during frying. All samples Pollut. Res., 2018, 25(3), 2580. analyzed did not show trans fatty acid components, 3. Gulia N., Dhaka V., Khatkar B. Instant noodles: indicating that process optimization was done and processing, quality, and nutritional aspects, Crit. Rev. tightly controlled. Food Sci. Nutr., 2014, 54(10), 1386. 4. Schenker, S. UK recommendations for dietary fat: Acknowledgements. We thank to all members of should they be reassessed in light of the recent joint Central Laboratory of Analysis for great supports in FAO/WHO recommendations?, 2012, 37-46. this study. This research is funded by University of 5. Tuan HQ, Son VH, Tu NTM. Fatty acid composition Science, VNU-HCM under grant number T2021-37. including trans fatty acids content of selected Vietnamese instant noodles, J. Sci. Technol., 2012, 10, 812. List of abbreviations 6. Aued-Pimentel S, Kus-Yamashita MM. Analysis of GC: Gas chromatography. the fat profile of industrialized food in Brazil with MS: Mass spectrometer. emphasis on trans-fatty acids, J. Food Compost and SFA: Saturated fatty acid. Anal., 2021, 97, 103799. MUFA: Monounsaturated fatty acid. 7. Golay P-A, Dionisi F, Hug B, Giuffrida F, Destaillats PUFA: Polyunsaturated fatty acid. F. Direct quantification of fatty acids in dairy powders FAMEs: Fatty acid methyl esters. with special emphasis on trans fatty acid content, Food Chem., 2007, 101(3), 1115. Conflict of interest statement. The authors declare 8. Rozema B, Mitchell B, Winters D, Kohn A, Sullivan D, Meinholz E. Proposed modifications to AOAC that they have no competing interests. 996.06, optimizing the determination of trans fatty acids: presentation of data. J. AOAC Int., 2008, 91(1), REFERENCES 92. 1. O. H. Adejuwon, A. I. Jideani, K. O. Falade. Quality Corresponding author: Nguyen Huy Du University of Science, VNU-HCM 227 Nguyen Van Cu road, Ho Chi Minh City 70000, Viet Nam Email: nhdu@hcmus.edu.vn Tel.: +84- 28 73089899. © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH www.vjc.wiley-vch.de 148