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Identification Of Adulterated Edible Oils By Raman Spectroscopy With Cooling Perturbation

Posted on:2021-02-07Degree:MasterType:Thesis
Country:ChinaCandidate:J F WangFull Text:PDF
GTID:2381330602989481Subject:Environmental engineering
Abstract/Summary:PDF Full Text Request
The adulteration of edible oil infringes on the interests of consumers and the public health.The relevant identification research is of great significance to construct a safe food environment.When the content of counterfeit ingredients in adulterated olive oil decreases,the similarity between adulterated oil and authentic oil is higher,which is the difficulty and key point of counterfeit identification.Two-dimensional spectrum using temperature as an external disturbance factor has attracts much attention in identifying adulterated edible oils,and heating was mainly used as a disturbance factor in the literature works.However,heating may cause some changes of the thermally unstable components in the edible oil and therefore affect the persuasion and accuracy of the identification results.In this thesis,two-dimensional correlation Raman spectra with cooling as perturbation factor,combined with Hierarchical clustering analysis,are used to carry out the identification of adulterated edible oilIn the range between+15 and-20?,the influence of temperature on the Raman spectra was studied in the pure olive oil and the adulterated olive oils mixed with low concentration(5%,10%,20%)soybean oil and corn oil.In the range between+15 and 0?,the Raman spectra of the pure olive oil and the adulterated oils were similar and changed slightly as the temperature decreased.When the temperature was below 0?,the peak shape and intensity of the Raman spectra of both pure olive oil and adulterated olive oils were significantly different along with the temperature decreased,and the difference between the Raman spectra of pure olive oil and adulterated olive oils became significant.In the two-dimensional synchronous correlation Raman spectra,the intensity of autocorrelation peak around 2900?2950 cm-1 and that of the cross peak(2925 cm-1,2883 cm-1)changed significantly along with the increase of the doping ratio.Hierarchical clustering analysis based on the two-dimensional synchronous correlation Raman spectroscopy data shows that the blind samples of the pure olive oil and the adulterated oils can all be accurately identified.Thereafter,soybean oil and corn oil were used as the genuine edible oils.Three kinds of gutter oils were mixed into the soybean oil and corn oil with low amounts(5%),respectively,so as to prepare 3 kinds of adulterated soybean oils and 3 kinds of adulterated corn oils.The Raman spectra of the genuine edible oils and the adulterated were collected and compared in the range between+15 and-30?.The Raman spectra of the pure soybean oil,the corn oil and the corresponding adulterated oils were very similar in the temperature range between+15 and 0?.When the temperature was below 0?,the Raman spectra of the pure soybean oil,corn oil and the corresponding adulterated edible oils change significantly;as the temperature decreases,the differences between pure oil and adulterated oils gradually increases.In the two-dimensional synchronous correlation Raman spectra,the authentic soybean oil showed a larger autocorrelation peak range around 2883 cm-1 than the adulterated soybean oil did.The intensity of the autocorrelation peak of the pure corn oil around 2883 cm-1 was observed to be higher in comparison with that of the adulterated corn oils.Hierarchical clustering analysis based on the two-dimensional synchronous correlation Raman spectra data showed that the blind samples of pure soybean oil,pure corn oil and adulterated oils were all accurately identified.In summary,the Raman spectra and the two-dimensional synchronous correlation Raman spectra with cooling as perturbation factor show a very high recognition ability for adulterated edible oils.This method can also be useful for the identification of other oil products.
Keywords/Search Tags:Raman spectrum, Two-dimensional synchronous correlation spectroscopy, Cluster analysis, edible oil, waste oil
PDF Full Text Request
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