Rapid detection of walnut and pumpkin oil adulteration using Raman spectroscopy and partial least square methodology


  • Anca BECZE INCDO-INOE2000, Research Institute for Analytical Instrumentation, ICIA Cluj-Napoca Subsidiary, 400293 Cluj-Napoca (RO)
  • Dorina SIMEDRU INCDO-INOE2000, Research Institute for Analytical Instrumentation, ICIA Cluj-Napoca Subsidiary, 400293 Cluj-Napoca (RO)




adulteration; partial least square methodology; Raman; pumpkin oil; walnut oils; spectroscopy; rapid detection


The purpose of this study is to develop a statistical method, based on Raman spectroscopy results, to quickly identify the adulteration of pumpkin and walnut oils. For this purpose, pure pumpkin and walnut oils from Cluj County, Romania were studied with Raman techniques. They were adulterated with sunflower oil at 14 levels of concentration, ranging from 2.5 to 50%. The areas under the significant peaks were quantified and compared. A statistical method using the partial least square methodology was developed and used as a prediction tool in order to establish the adulteration percentage for pumpkin and walnut oils. 4 components were used to model the equation, the peak areas from ~1264, ~1300, ~1441 and respectively ~1659 cm-1. The final model equations take into account only the peak areas that had a high impact on the prediction values, statistically proven using the p-value. The level of prediction obtained with the final model equation was ≥ 95%.


Abbas O, Baeten V (2016). Advances in the identification of adulterated vegetable oils. In: Downey G (Ed). Advances in Food Authenticity Testing. Woodhead Publishing (1st ed), Duxford, United Kingdom pp 519-542.

Abou-Zeid SM, AbuBakr HO, Mohamed MA, El-Bahrawyd A (2018). Ameliorative effect of pumpkin seed oil against emamectin induced toxicity in mice. Biomedicine & Pharmacotherapy 98:242-251. https://doi.org/10.1016/j.biopha.2017.12.040

Aykas DP, Karaman AD, Keser B, Rodriguez-Saona L (2020). Non-targeted authentication approach for extra virgin olive oil. Foods 9:221. https://doi.org/10.3390/foods9020221

Azadmard-Damirchi S, Torbati M (2015). Adulterations in some edible oils and fats and their detection methods. Journal of Food Quality and Hazards Control 2:38-44.

Breslow JL (2006). N-3 fatty acids and cardiovascular disease. The American Journal of Clinical Nutrition 83:S1477- S1482. https://doi.org/10.1093/ajcn/83.6.1477S

Chen B, Tian P, Lu DL, Zhou ZQ, Shao ML (2012). Feasibility study of discriminating edible vegetable oils by 2D NIR, Analytical Methods 4:4310-4315. https://doi.org/10.1039/C2AY25962A

Conlon LE, King RD, Moran NE, Erdman Jr. JW (2012). Coconut oil enhances tomato carotenoid tissue accumulation compared to safflower oil in the Mongolian gerbil (Meriones unguiculatus). Journal of Agricultural and Food Chemistry 60:8386-8394. https://doi.org/10.1021/jf301902k

Dodge Y (2008). The concise encyclopaedia of statistics. Springer-Verlag New York, pp 493-537.

Elfiky SA, Elelaimy IA, Hassan AM, Ibrahim HM, Elsayad RI (2012). Protective effect of pumpkin seed oil against genotoxicity induced by azathioprine The Journal of Basic & Applied Zoology 65:289-298. https://doi.org/10.1016/j.jobaz.2012.10.010

Farres S, Srata L, Fethi F, Kadaoui A (2019). Argan oil authentication using visible/near infrared spectroscopy combined to chemometrics tools. Vibrational Spectroscopy 102:79-84. https://doi.org/10.1016/j.vibspec.2019.04.003

Fawzy EI, El Makawy AI, El-Bamby MM, Elhamalawy HO (2018). Improved effect of pumpkin seed oil against the bisphenol-A adverse effects in male mice. Toxicology Reports 5:857-863. https://doi.org/10.1016/j.toxrep.2018.08.014

Food and Agriculture Organization of the United Nations FAOSTAT (2004). Inventory of walnut research, germplasm and references. Retrieved 2020 April 30 from http://www.fao.org/3/y5704e/y5704e03.htm#TopOfPage

Hammond EW (2003). Vegetable oils. In: Caballero B, Finglas P, Toldra F (Eds). Encyclopedia of Food Sciences and Nutrition. Academic Press (2nd ed), London, United Kingdom pp 5899-5904.

Hatzakis E (2013). Quality assessment and authentication of virgin olive oil by NMR spectroscopy: a critical review. Analytica Chimica Acta 765:1-27. https://doi.org/10.1016/j.aca.2012.12.003

Hornstra G, Al MDM, Houwelingen ACV, Foreman-van Drongelen MMHP (1995). Essential fatty acids in pregnancy and early human development. European Journal of Obstetrics & Gynecology and Reproductive Biology 61:157-162. https://doi.org/10.1016/0028-2243(95)02153-J

Kumar A, Sharma A, Upadhyaya KC (2016). Vegetable oil: nutritional and industrial perspective. Current Genomics 17:230-240. https://doi.org/10.2174/1389202917666160202220107

Li B, Wang H, Zhao Q, Ouyang J, Wu Y (2015). Rapid detection of authenticity and adulteration of walnut oil by FTIR and fluorescence spectroscopy: A comparative study. Food Chemistry 181:25-30. https://doi.org/10.1016/j.foodchem.2015.02.079

Li Y, Fang T, Zhu S, Huang F, Chen Z, Wang Y (2018). Detection of olive oil adulteration with waste cooking oil via Raman spectroscopy combined with iPLS and SiPLS. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 189:37-43. https://doi.org/10.1016/j.saa.2017.06.049

Man YBC, Rohman A, Mansor T (2011). Differentiation of lard from other edible fats and oils by means of Fourier transform infrared spectroscopy and chemometrics. Journal of the American Oil Chemists' Society 88:187-192. https://doi.org/10.1007/s11746-010-1659-x

Man YBC, Rohman A (2013). Analysis of canola oil in virgin coconut oil using FTIR spectroscopy and chemometrics. Journal of Food and Pharmaceutical Sciences 1:5-9. https://doi.org/10.14499/jfps

Martínez ML, Labuckas DO, Lamarque AL, Maestri DM (2010). Walnut (Juglans regia L.): Genetic resources, chemistry, by-products. Journal of the Science of Food and Agriculture 90:1959-1967. https://doi.org/10.1002/jsfa.4059

McMathis J (2015). Ancient pottery unearthed in Israel contains 8000-year-old olive oil. Israel Journal of Plant Sciences 62:65-74.

Meenu M, Cai Q, Xu B (2019). A critical review on analytical techniques to detect adulteration of extra virgin olive oil. Trends in Food Science & Technology 91:391-408. https://doi.org/10.1016/j.tifs.2019.07.045

Mendes TO, da Rocha RA, Porto BLS, de Oliveira MAL, dos Anjos VDC, Bell MJ (2015). Quantification of extra–virgin olive oil adulteration with soybean oil: a comparative study of NIR, MIR, and Raman spectroscopy associated with chemometric Approaches. Food Analytical Methods 8:2339-2346.


Minitab (2020). Example of getting and interpreting a p-value. Retrieved 2020 14th July from https://support. minitab.com/en-us/minitab/18/help-and-how-to/statistics/basic-statistics/supporting-topics/basics/example-of-getting-and-interpreting-a-p-value/

Minitab (2020). Model summary table for Fit General Linear Model. Retrieved 2020 July 11 from https://support.minitab.com/en-us/minitab/18/help-and-how-to/modeling-statistics/anova/how-to/fit-general-linear-model/interpret-the-results/all-statistics-and-graphs/model-summary-table/

Nam YS, Noh KC, Roh EJ, Keum G, Lee Y, Lee KB (2014). Determination of edible vegetable oil adulterants in sesame oil using 1 h nuclear magnetic resonance spectroscopy. Analytical Letters 47:1190-1200. https://doi.org/10.1080/00032719.2013.865199

Nederal S, Petrovic M, Vincek D, Pukec D, Skevin D, Kraljic K, Obranovic M (2014). Variance of quality parameters and fatty acid composition in pumpkin seed oil during three crop seasons. Industrial Crops and Products 60:15-21. https://doi.org/10.1016/j.indcrop.2014.05.044

Negi AS, Luqman S, Srivastava S, Krishna V, Gupta N, Darokar MP (2011). Antiproliferative and antioxidant activities of Juglans regia fruit extracts. Pharmaceutical Biology 49:669-673. https://doi.org/10.3109/13880209.2010.537666

Nishimura M, Ohkawara T, Sato H, Takeda H, Nishihira J (2014). Pumpkin seed oil extracted from Cucurbita maxima improves urinary disorder in human overactive bladder. Journal of Traditional and Complementary Medicine 4:72‑74. https://doi.org/10.4103/2225-4110.124355

Parker T, Limer E, Watson AD, Defernez M, Williamson D, Kemsley EK (2014). 60 MHz 1 H NMR spectroscopy for the analysis of edible oils. TrAC Trends in Analytical Chemistry 57:147-158. https://doi.org/10.1016/j.trac.2014.02.006

Rabadán A, Pardo JE, Gómez R, Álvarez-Ortí M (2018). Evaluation of physical parameters of walnut and walnut products obtained by cold pressing. LWT 91:308-314. https://doi.org/10.1016/j.lwt.2018.01.061

Roccisano D, Kumaratilake J, Saniotis A, Henneberg M (2016). Dietary fats and oils: some evolutionary and historical perspectives concerning edible lipids for human consumption. Food and Nutrition Sciences 7:689-702. https://doi.org/10.4236/fns.2016.78070

Seif HAS (2014). Ameliorative effect of pumpkin oil (Cucurbita pepo L.) against alcohol-induced hepatotoxicity and oxidative stress in albino rats. Beni-Suef University Journal of Basic and Applied Sciences 3:178-185. https://doi.org/10.1016/j.bjbas.2014.08.001

Shi T, Zhu MT, Chen Y, Yan XL, Chen Q, Wu XL, Lin J, Xie M (2018). 1H NMR combined with chemometrics for the rapid detection of adulteration in camellia oils. Food Chemistry 242:308-315. https://doi.org/10.1016/j.foodchem.2017.09.061

Soyinfo Center (2007). History of soybean crushing: soy oil and soybean meal-Part 1. Retrieved 2020 February 10 from https://www.soyinfocenter.com/HSS/soybean_crushing1.php

Statista (2020). Vegetable oil production worldwide 2000-2020. Retrieved 2020 March 25 from https://www.statista.com/statistics/263978/global-vegetable-oil-production-since-2000-2001/

Statista (2020). Vegetable oils: global consumption by oil type 2013/14 to 2019/2020. Retrieved 2020 February 12 from https://www.statista.com/statistics/263937/vegetable-oils-global-consumption/

Statsdirect (2020). P Values. Retrieved 2020 August 17 from https://www.statsdirect.com/help /basics/p_values.htm

Velioglu SD, Ercioglu E, Temiz HT, Velioglu HM, Topcu A, Boyaci IH (2016). Raman spectroscopic barcode use for differentiation of vegetable oils and determination of their major fatty acid composition. Journal of the American Oil Chemists' Society 93:627-635. https://doi.org/10.1007/s11746-016-2808-7

Wei D, Zhang YQ, Zhang B, Wang XP (2013). Rapid prediction of fatty acid composition of vegetable oil by Raman spectroscopy coupled with least squares support vector machines. Journal of Raman Spectroscopy 44:1739-1745. https://doi.org/10.1002/jrs.4386

Wong A, Viola D, Bergen D, Caulfield E, Mehrabani J, Figueroa A (2019). The effects of pumpkin seed oil supplementation on arterial hemodynamics, stiffness and cardiac autonomic function in postmenopausal women. Complementary Therapies in Clinical Practice 37:23-26. https://doi.org/10.1016/j.ctcp.2019.08.003

Yuan Z, Zhang L, Wang D, Jiang J, B. Harrington P, Mao J, Zhang Q, Li P (2020). Detection of flaxseed oil multiple adulteration by near-infrared spectroscopy and nonlinear one class partial least squares discriminant analysis, LWT 125:109247. https://doi.org/10.1016/j.lwt.2020.109247




How to Cite

BECZE, A., & SIMEDRU, D. (2020). Rapid detection of walnut and pumpkin oil adulteration using Raman spectroscopy and partial least square methodology. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 48(3), 1426–1438. https://doi.org/10.15835/nbha48312024



Research Articles
DOI: 10.15835/nbha48312024

Most read articles by the same author(s)