Monitoring the quality of potato crisps and occuring processing contaminants

Acrylamide is a carcinogenic, genotoxic and neurotoxic processing contaminant and usually found in foods that are rich in carbohydrates and are thermally processed such as; bread, coffee and potato chips. Maillard reaction with free asparagine as core precursor is the base pathway of acrylamide generation in foods. Choloropropanols are food-borne process contaminants, arising from acid-hydrolyzed vegetable protein. Monochloropropandiol (MCPD) esters and glycidyl esters are composed by being subjected to high temperature of oils and are process contaminants in foods. MCPD esters are carcinogenic in vitro, but in vivo it is evaluated as a non-genotoxic compound. In addition to that, fatty acid esters of glycidol are carcinogenic in in vivo studies and have genotoxic mechanism. Deodorization process in edible oil production is the main track of these heat-induced process contaminants formations. Also, glycidyl esters are generated in due course of refining of commercially available edible oils, besides it might be formed by the reason of other food processing techniques. 6 brands of potato crisps with different flavours and fried oils (according to their label descriptions) were bought from a local supermarket in Czech Republic. The used frying oils in the samples were sunflower oil, palm oil, rapeseed oil and specified or unspecified mixtures of vegetable oils. Fat extraction was performed in order to make 3-MCPD and glycidyl esters analysis by using HPLC-MS/MS and U-HPLC-HRMS, respectively. All samples were homogenized for acrylamide analysis and fat extraction. Also, fats were analyzed to observe chemical changes TAGs, phytosterols, FFAs and their oxidation products in fried oils by transmission-mode direct analysis in real time ionization coupled with high resolution mass spectrometry (TM-DART-HRMS). For statistical evaluation SIMCA 13.0 software package was used for PCA. There is no correlation between the type of oil and acrylamide content according to the results of the analysis. Besides, acrylamide concentrations diverged not only from brands to brands, but also within some producers. The data range of the analysis is between 205 and 1252 µg/kg, which is congruent with other studies 591–1999 µg/kg. According to the analysis the samples "VV 28/15" and "VV 360/15" have the highest acrylamide content. The lowest acrylamide content was in the samples "VV 31/15" and "VV 34/15". It is apparent that the amount of 3-MCPD fatty acid esters is relevant to the content of lipids in these products. Samples fried with sunflower and rapeseed oil contain much lower bound 3-MCPD esters than samples fried with palm oil or mixtures including palm oil. It was shown that potato crisps fat is largely composed of oil used for frying crisps. Our analysis proved that using palm oil for frying the potato crisps was a precursor for bound 3-MCPD esters formation. Similarly, another study also shows that bound 3-MCPD esters are contained in refined edible oils, particularly in refined palm oil. The study showed that "VV 29/15" has the highest amount of glycidyl esters. On the whole, glycidyl oleate is the highest amount of glycidyl ester amid the samples. The same sample has besides the highest amount of 3-MCPD. According to other studies, there was some correlation between the generation of 3-MCPD and glycidyl esters due to the direct correlation of between DAG content and those. In reference to DART analysis, the most prevalent ion effecting the separation of samples (VV26/15, VV29/15, VV31/15, VV33/15) fried in palm oil or in a mixture of 60% palm oil and 40 % sunflower oil was palmitic acid (m/z 255,2329). In the mass region of the spectra, molecular [M+NH4]+ adduct ions formed from TAGs can be observed. Depending on the accurate mass measurement and elemental formula estimations of selective ions were determined. According to the PCA plots obtained from SIMCA statistical software, dilinoleoyl-oleoylglycerols (LLO) was the selective ion for VV 360/15, VV 361/15 and VV 362/15 which were fried with sunflower oil. The samples which were fried with rapeseed oil linoleoyl-dioleoylglycerols (LOO) was the selective ion from other samples (VV 28/15 and VV 30/15). LOO is the primary TAG for rapeseed oil and LLO is primary TAG for sunflower oil. Another selective ion of the other group of samples (VV 23/15, VV 24/15, VV 27/15, VV 32/15, VV 34/15) which sunflower oil is used to fry, was trioleoglycerol (OOO). Moreover, LOO was the most oxidized TAG in the samples. Phytosterols are minor components of vegetable oils, but it is significant to find out possible adulteration since some vegetable oils have specific phytosterols such as brassicasterol is a specific phytosterol for rapeseed oil and it is clearly seen in our samples fried in rapeseed oil. Variations in the mass spectra of the oils through heat were caused mainly by increased intensities of FFAs. Linoleic acid was the selective ion for all 3 samples (VV 360/15, VV 361/15 and VV 362/15) which were fried with sunflower oil. It is clearly observed the intensities of FFAs and its oxidation products with the extent of oxidation in the plots. Furthermore, it is clearly seen that the samples fried in palm oil or its mixture have more palmitic acid than the other samples. In addition, linoleic acid was the most oxidized fatty acid generally among the samples. In short, there is no correlation between the type of used frying oil and acrylamide content of potato crisps according to the study. Seemingly, frying temperature is more determinant for acrylamide rather than oil composition. Yet, oil composition is very important in terms of 3-MCPD and glycidyl ester generation. Our 3-MCPD and glycidyl esters analyses were relevant to the literature and palm oil itself or in an oil mixture increases 3-MCPD and glycidyl ester generation. Thus, it could be suggested that during potato crisp processing, frying oil composition should be taken into consideration.