Furan Occurrence in Starchy Foods - PDF

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Article pubs.acs.org/JAFC Furan Occurrence in Starchy Food Model Systems Processed at High Temperatures: Effect of Ascorbic Acid and Heating Conditions María Mariotti,*,† Kit Granby,‡ Arvid Fromberg,‡ Jørgen Risum,‡ Eduardo Agosin,†,§ and Franco Pedreschi†,§ † Department of Chemical and Bioprocess Engineering, Pontificia Universidad Católica de Chile (PUC), Box 306, 6904411 Santiago, Chile ‡ National Food Institute, Technical University of Denmark (DTU), Mørkhøj Bygade 19, Søborg, DK-2860 Copenhagen, Denmark § ASIS-UC Interdisciplinary Research Program on Tasty and Healthy Foods, Pontificia Universidad Católica de Chile (PUC), Downloaded via DTIC NATL TECH INFORMATION CTR on November 27, 2023 at 14:16:02 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles. Casilla 306, Correo 22 Santiago, Chile ABSTRACT: Furan, a potential carcinogen, has been detected in highly consumed starchy foods, such as bread and snacks; however, research on furan generation in these food matrixes has not been undertaken, thus far. The present study explored the effect of ascorbic acid addition and cooking methods (frying and baking) over furan occurrence and its relation with the non- enzymatic browning in a wheat flour starchy food model system. Results showed that furan generation significantly increased in the presence of ascorbic acid after 7 min of heating (p < 0.05). The strongest effect was observed for baked products. Additionally, the furan content in fried products increased with the increase of the oil uptake levels. As for Maillard reactions, in general, the furan level in all samples linearly correlated with their degree of non-enzymatic browning, represented by L* and a* color parameters (e.g., wheat flour baked samples showed a R2 of 0.88 and 0.87 for L* and a*, respectively), when the sample moisture content decreased during heating. KEYWORDS: Furan, starchy food model system, ascorbic acid, oil uptake, moisture, non-enzymatic browning INTRODUCTION Furan is a potential human carcinogen that can be formed in a Few authors have evaluated furan generation in more real sys- tems that considered the interaction between potential pre- cursors. Limacher et al.13 and Van Lancker et al.14 determined broad range of foods processed at high temperatures, such as furan formation from the Maillard reaction in carbon module coffee, baby foods, bread, and snacks.1 Although it is still unclear labeling (CAMOLA) model systems under both dry-roasting what the risks are associated with the current intake levels of and pressure-cooking conditions. They concluded that glucose- dietary furan, furan mitigation in foods may be considered a derived furan was formed from the intact sugar skeleton and not challenge in the prevention of human diseases, such as cancer.2 from fragmentation and recombination mechanisms. However, The presence of furan is common in foods processed at high some amino acids (especially alanine and serine) could provide temperatures, particularly in products packed in sealed contain- an additional formation pathway, as previously proposed.15 ers (e.g., baby foods). Because of its low boiling point, furan The role of ascorbic acid and PUFAs on furan occurrence has generated during thermal processes easily vaporized, accumulat- recently been investigated16 in starchy model systems that mimic ing in the headspace of canned or jarred foods.3 However, despite baby foods. The authors showed that, for CAMOLA model sys- its high volatility, furan has also been found in low-moisture foods tems heated under roasting conditions, the furan formation from processed in open containers, such as potato chips, crackers, crisp ascorbic acid was significantly reduced in binary mixtures (e.g., breads, and toasted breads.3−6 the presence of erythrose led to 80% less furan). These results The broad number of foods that have been shown to contain agreed with previous findings, in which simple binary mixtures of furan suggests that multiple pathways might be involved in its ascorbic acid and amino acids, sugars, or lipids could reduce furan formation in foods.7 Thermal degradation and rearrangement of by 50−95%.17 Thus, more complex reaction systems result in sugars was suggested as the primary source of furan in food;8 more lower furan generation, as compared to the individual precursors, recently, amino acids, polyunsaturated fatty acids (PUFAs), and most likely because of competing reaction pathways. Owczarek- ascorbic acid have also been implicated.1,3,6,8−11 The latter formed Fendor et al.18 observed, however, that the presence of starch the highest amount of furan in aqueous model systems heated at drastically enhanced furan formation from ascorbic acid. They high temperature. hypothesized that furan synthesis was stimulated when ascorbic It is worth noting that the furan content determined in foods acid was incorporated in the starchy gel (inclusion complex); was much lower than predicted from trials with pure ascorbic acid. Therefore, caution must be drawn about the plausibility of the Received: May 24, 2012 proposed pathways for furan formation determined in model Revised: September 12, 2012 systems and their direct extrapolation to the more complex food Accepted: September 17, 2012 products.12 Published: September 17, 2012 © 2012 American Chemical Society 10162 dx.doi.org/10.1021/jf3022699 | J. Agric. Food Chem. 2012, 60, 10162−10169 Journal of Agricultural and Food Chemistry Article Figure 1. Role of ascorbic acid over furan formation in starchy food model systems processed at high temperatures. Error bars represent standard deviations (n = 3). thus, its degradation was favored over the condensation with Chemical reagents for furan analyses were (i) furan (>99%, Sigma- other compounds present in the reaction medium. Aldrich, Steinheim, Germany), (ii) d4-furan (98 atom % D, Isotec, The furan formation from lipid oxidation was influenced by Miamisburg, OH), (iii) methanol [high-performance liquid chromatog- not only the fatty acid composition but also the interactions with raphy (HPLC) grade, Rathburn, Walkerburn, Scotland], and (iv) NaCl (>99%, Merck, Darmstadt, Germany). Finally, petroleum ether (>99%, other matrix ingredients.19 For example, while linolenic acid Sigma-Aldrich, Steinheim, Germany) was used as an extraction solvent has been identified as responsible for furan generation in most for oil determination by Soxhlet. research studies,15,19−22 the importance of the degree of fat Dough Preparation. Dough formulations were prepared on the oxidation is still unclear. Finally, the effect of different intrinsic basis of the criteria that both formulations (with and without ascorbic and extrinsic factors, such as pH, matrix, and heating temper- acid) would have the same moisture content of 40 ± 0.6% wb before atures also considerably impact both furan generation and its being fried or baked. To calculate the amount of water that had to be retention.1,3,5,12,23,24 added to the solid materials, the exact dry solid content of wheat flour Because high levels of furan were found in baby foods, most was determined experimentally by drying it until a constant weight. For model systems focused in replicating as reliably as possible the WF−AA samples, anhydrous ascorbic acid was added in a concentration of 300 mg/kg of wheat flour. Then, the amount of wheat flour, ascorbic physicochemical features of these matrices. To the best of our acid, and water necessary to prepare 500 g of each dough formulation knowledge, research on furan generation in other food matrixes, was calculated on a dry basis (db). For WF and WF−AA formulations, such as bread, crackers, or potato chips, where its presence was 100 and 99.5% of wheat flour (db) was added. In WF−AA formulation demonstrated, has not yet been carried out. Considering the sig- near 0.5% (db) corresponded to the ascorbic acid necessary to reach the nificant worldwide consumption of thermally processed starchy required concentration. foods, in this work, we investigated the mechanisms involved in WF and WF−AA dough formulations were prepared using a food furan generation in these matrixes. The present study explored mixer (Teddy Bear Varimixer, Copenhagen, Denmark), and water was the effect of ascorbic acid and heating conditions (frying and added according to the protocol previously described.26 Half of the baking) over furan occurrence, as well as the relationships be- water was gradually added at 15 °C while mixing for 1 min. After mixing for 1 extra min, the remaining water previously heated at 90 °C was tween non-enzymatic browning and furan content in a starchy added to the dough and then all of the ingredients were homogenized for food model system. 2 min. The resultant dough was then wrapped in a plastic bag and left for Finally, because these low-moisture starchy food products are 1 h at room temperature (20 °C). Then, the dough was kneaded to characterized by the development of non-enzymatic brown- ensure homogeneity, laminated to obtain the required thickness using a ing during high-temperature processing,25 we explored if color dough sheeter (Rollmatic, Vicenza, Italy), and cut into 40 mm diameter development could be a good predictor of furan generation. circles. The exact thickness of the resultant dough slices ranged from 2 to 2.3 mm. Approximately 500 g of dough was prepared for each batch of the experiment. MATERIALS AND METHODS Thermal Processing of Dough. The resulting samples were fried Two different dough formulations with the same moisture content and baked at 170 and 200 °C for 5, 7, and 9 min. of 40% on a wet basis (wb) were prepared: (i) wheat flour (WF) and (ii) Frying Conditions. The samples were fried in a 20 L capacity deep- wheat flour and ascorbic acid (WF−AA). Then, both formulations were fryer (FKI, Copenhagen, Denmark). The fryer was filled with 15 L of oil laminated and cut in circle slices to be either baked or fried. The furan that was preheated for 2 h prior to frying27 and was discarded after 90 concentration of the fried or baked slices on a dry defatted weight basis min of frying time. The chip/oil mass ratio was maintained as low as (ddb) was quantified by gas chromatography coupled with mass possible to keep a constant temperature of frying. Throughout the frying spectrometry (GC/MS). Finally, color development of the cooked process, 10 chips of 3.7 ± 0.03 g were placed in a basket and held in samples was quantified in L*, a*, and b* units using a colorimeter. position with a wire grid to prevent them from floating. The fried chips Materials. Dough formulations were prepared with the following were drained over a wire screen for 5 min.28 After that, drained samples materials: (i) wheat flour (moisture content of 15% on a wb), (ii) were homogenized and refrigerated for 30 min. Then, chemical and anhydrous ascorbic acid ( 0.05) until the moisture content also for WF−AA fried products, the amount of furan generated was below 12% (ddb), achieving the highest values at moisture increased during frying, similar to oil uptake (Figure 2). levels of 2.23 and 2.77% (ddb) for WF (102.32 ng/g of dds) and Some authors have suggested that the overall role of lipids in WF−AA (182.04 ng/g of dds) fried samples and 6.22 and 5.48% furan formation was restricted in practice, because it is necessary (ddb) for WF (52.36 ng/g of dds) and WF−AA (227.00 ng/g of 10167 dx.doi.org/10.1021/jf3022699 | J. Agric. Food Chem. 2012, 60, 10162−10169 Journal of Agricultural and Food Chemistry Article dds) baked samples, respectively. Similar results were found in (6) Zoller, O.; Sager, F.; Reinhard, H. Furan in food: Headspace carrot slices37 and hazelnuts,21 which were dried at temperature method and product survey. Food Addit. Contam. 2007, 24 (Supple- ranges of 113−133 and 50−150 °C, respectively. ment), 91−107. Relation between the Furan Content and Non- (7) Morehouse, K. M.; Nyman, P. J.; McNeal, T. P.; Dinovi, M. J.; Perfetti, G. A. Survey of furan in heat processed foods by headspace gas enzymatic Browning. The presence of furan in foods is chromatography/mass spectrometry and estimated adult exposure. related to the thermal degradation of carbohydrates, ascorbic Food Addit. Contam. 2008, 25, 259−264. acid, amino acid, and PUFAs.9 Considering that non-enzymatic (8) Fan, X. Formation of furan from carbohydrates and ascorbic acid browning in low-moisture starchy foods is also a consequence of following exposure to ionizing radiation and thermal processing. J. Agric. these reactions,38 we determined the color development of WF Food Chem. 2005, 53, 7826−7831. and WF−AA formulations processed at high temperatures. (9) Maga, J. A. Furans in foods. CRC Crit. Rev. Food Sci. Nutr. 1979, 11, Figures 4 and 5 show that color represented by the parameters L* 355−400. and a* followed linear correlations with the furan content, for (10) Van Lancker, F.; Adams, A.; Owczarek-Fendor, A.; De Meulenaer, both frying (WF formulation, R2 of 0.72 and 0.82 for L* and a* B.; De Kimpe, N. Mechanistic insights into furan formation in Maillard values, respectively; WF−AA formulation, R2 of 0.56 and 0.94 for model systems. J. Agric. Food Chem. 2010, 59, 229−235. L* and a* values, respectively) and baking (WF formulation, R2 (11) Vranova, J.; Ciesarova, Z. Furan in foodA review. Czech J. Food Sci. 2009, 27, 1−10. of 0.70 and 0.88 for L* and a* values, respectively; WF−AA (12) Roberts, D.; Crews, C.; Grundy, H.; Mills, C.; Matthews, W. formulation, R2 of 0.72 and 0.87 for L* and a* values, respec- Effect of consumer cooking on furan in convenience foods. Food Addit. tively) experiments. These results suggest that preliminarily color Contam. 2008, 25, 25−31. development could be considered as a good predictor of furan (13) Limacher, A.; Kerler, J.; Davidek, T.; Schmalzried, F.; Blank, I. formation in starchy matrixes. Lower correlation values obtained Formation of furan and methylfuran by Maillard-type reactions in model for lightness in fried products could be attributed to distortion systems and food. J. Agric. Food Chem. 2008, 56, 3639−3647. effects caused by oil located in the fried sample surface. (14) Van Lancker, F.; Adams, A.; Owczarek-Fendor, A.; De Meulenaer, L* values tended to decrease with the processing time because B.; De Kimpe, N. Mechanistic insights into furan formation in Maillard the samples become darker on the surface as a result of non- model systems. J. Agric. Food Chem. 2010, 59, 229−235. enzymatic browning reactions. On the other hand, the a* value (15) Perez Locas, C.; Yaylayan, V. A. Origin and mechanistic pathways showed an increase during the tested cooking processes because of formation of the parent furanA food toxicant. J. Agric. Food Chem. 2004, 52, 6830−6836. the sample surface obtained more red coloration as a result of the (16) Limacher, A.; Kerler, J.; Conde-Petit, B.; Blank, I. Formation of reactions mentioned before. Interestingly, these results agreed furan and methylfuran from ascorbic acid in model systems and food. with those obtained by other researchers when they studied Food Addit. Contam. 2007, 24, 122−135. acrylamide formation phenomena in real systems, such as potato (17) Mark, J.; Pollien, P.; Lindinger, C.; Blank, I.; Mark, T. chips and French fries.39−41 The Maillard reaction might be the Quantitation of furan and methylfuran formed in different precursor main route of formation of furan in low-moisture starchy foods. systems by proton transfer reaction mass spectrometry. J. Agric. Food AUTHOR INFORMATION Corresponding Author Chem. 2006, 54, 2786−2793. (18) Owczarek-Fendor, A.; De Meulenaer, B.; Scholl, G.; Adams, A.; Van Lancker, F.; Yogendrarajah, P.; Eppe, G.; De Pauw, E.; Scippo, M.- L.; De Kimpe, N. Furan formation from vitamin C in a starch-based *Telephone: +56-2-3541269. Fax: +56-2-3547962. E-mail: model system: Influence of the reaction conditions. Food Chem. 2010, [email protected]. 121, 1163−1170. Funding (19) Owczarek-Fendor, A.; De Meulenaer, B.; Scholl, G.; Adams, A.; The authors appreciate the financial support of the Technical Van Lancker, F.; Eppe, G.; De Pauw, E.; Scippo, M.-L.; De Kimpe, N. University of Denmark, the National Food Institute, the Furan formation from lipids in starch-based model systems, as FONDECYT Project 1110510, and grants from CONICYT influenced by interactions with antioxidants and proteins. J. Agric. and the School of Engineering at PUC. Food Chem. 2011, 59, 2368−2376. 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