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ABSTRACT: This work was addressed to study the influence of radiofrequency (RF) heating on acrylamide (AA) formation in bakery products.
To this purpose, leavened cakes and short dough biscuits were baked to a final moisture of 3.5 and 3.0%, respectively, by
means of conventional convection heating or different combinations of conventional and RF heating. Results showed that, with
respect to the baking process entirely carried out in an air-circulating oven, the RF-assisted baking process, i.e. the application
of RF heating in the last stages of the baking process, resulted to be a promising strategy to keep low the AA levels in the
bakery products. In particular, the best results were obtained for products which were moved from the hot-air baking to the
RF heating when their residual moisture was still fairly high (around 10%). Results also suggested that, when very low values
of residual moisture are required, this technological intervention is more suitable to thin bakery products, such as biscuits,
than to thick products, such as leavened cakes, because of excessive browning in the internal portion as a consequence of
the RF heating.
European Food Research and Technology 04/2012; 226(5):1197-1203. · 1.57 Impact Factor
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ABSTRACT: In April 2002, unexpected high levels of the neurotoxic and suspected carcinogen acrylamide (AA) were found in many heated foods, mainly represented by cereal and potato derivatives. Since then, due to the great consumption of dietary sources of AA among people of different ages and in different countries, worldwide efforts have been carried out to reduce the formation of the toxic molecule in foods. In this paper, the effect of a low-temperature long-time pre-treatment of wheat grains on AA formation in biscuits was investigated. Wheat grains were subjected to heating at 100 degrees C for 8 h and subsequently milled. The obtained flour was used to prepare biscuits that were compared for AA content, texture and color with control samples obtained by using flour from unheated wheat. The low-temperature long-time pre-treatment was responsible for a great decrease (up to 42%) in AA levels in the biscuits, without causing significant changes in the color and texture parameters. As the pre-treatment did not cause any change in sugar and asparagine concentrations, such a reduction in AA concentration can be attributed to a difference in the thermal effect generated in the biscuits obtained by using the unheated and pre-heated flours. In fact, as the heating pre-treatment caused a 2% moisture decrease in the flour, less time at the same temperature was required to obtain biscuits with comparable moisture contents.
Molecular Nutrition & Food Research 09/2009; 53(12):1526-31. · 4.30 Impact Factor
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ABSTRACT: The mite Varroa destructor Anderson & Trueman is a parasite of the honeybee Apis mellifera L. and represents a major threat for apiculture in the Western world. Reproduction takes place only inside bee brood cells that are invaded just before sealing; drone cells are preferred over worker cells, whereas queen cells are not normally invaded. Lower incidence of mites in queen cells is at least partly due to the deterrent activity of royal jelly. In this study, the repellent properties of royal jelly were investigated using a lab bioassay. Chemical analysis showed that octanoic acid is a major volatile component of royal jelly; by contrast, the concentration is much lower in drone and worker larval food. Bioassays, carried out under lab conditions, demonstrated that octanoic acid is repellent to the mite. Field studies in bee colonies confirmed that the compound may interfere with the process of cell invasion by the mite.
Naturwissenschaften 01/2009; 96(2):309-14. · 2.28 Impact Factor
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ABSTRACT: The antioxidant activity of 12 aqueous commercial smoke flavorings used in the food industry was determined by two methods: bleaching of the carotenoid crocin and scavenging of the DPPH radical. The reaction with the DPPH radical was evaluated by calculating the effective concentration (EC50) and the antiradical efficiency (AE). A gas chromatography-mass spectrometry method was, moreover, used for the determination of 2-methoxyphenols, 2,6-dimethoxyphenols, and dihydroxybenzenes. The methoxyphenols were extracted from the aqueous smoke by dichloromethane, and also the residue aqueous phase was analyzed to determine the more water-soluble dihydroxybenzenes. The recovery and the repeatability of the method are reported. The total phenolic concentrations of the smoke flavorings showed a wide range, from about 1000 to 25000 mg/kg. Considering the three classes of compounds, the concentrations were about 300-3000 mg/kg for the 2-methoxyphenols, 200-11000 mg/kg for the 2,6-dimethoxyphenols, and 140-10000 mg/kg for the dihydroxybenzenes. The range of the antioxidant activities of the smoke flavorings was wide, reflecting the wide range of the phenolic concentrations. Good correlations were obtained between the total phenolic concentration and the antioxidant activities determined by both the DPPH and crocin assays.
Journal of Agricultural and Food Chemistry 05/2008; 56(8):2727-34. · 2.82 Impact Factor
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ABSTRACT: The content of phytosterol oxidation products was determined in samples of crude vegetable oils: peanut, sunflower, maize, palm nut, and lampante olive oils that were intended for refining and not for direct consumption. The 7 alpha- and 7 beta-hydroxy derivatives of beta-sitosterol, stigmasterol, and campesterol and the 7-keto-beta-sitosterol were the principal phytosterol oxides found in almost all of the oils analyzed. In some oils, the epoxy and dihydroxy derivatives of beta-sitosterol were also found at very low levels. The highest total concentrations of phytosterol oxides, ranging from 4.5 to 67.5 and from 4.1 to 60.1 ppm, were found in sunflower and maize oils, respectively. Lower concentrations were present in the peanut oils, 2.7-9.6 ppm, and in the palm nut oil, 5.5 ppm, whereas in the lampante olive oils, only three samples of the six analyzed contained a low concentration (1.5-2.5 ppm) of oxyphytosterols. No detectable levels of phytosterol oxides were found in the samples of palm and coconut oils. Bleaching experiments were carried out on a sample of sunflower oil at 80 degrees C for 1 h with 1 and 2% of both acidic and neutral earths. The bleaching caused a reduction of the hydroxyphytosterol with partial formation of steroidal hydrocarbons with three double bonds in the ring system at the 2-, 4-, and 6-positions (steratrienes). The same sunflower oil was deodorized at 180 degrees C under vacuum for 1 h, and no dehydration products were formed with a complete recovery of the hydroxyphytosterols. A bleaching test with acidic earths was carried out also with an extra virgin olive oil fortified with 7-keto-cholesterol, dihydroxycholesterol, and alpha-epoxy-cholesterol. There was no formation of steratrienes from these compounds, but dihydroxycholesterol underwent considerable decomposition and alpha-epoxycholesterol underwent ring opening with formation of the dihydroxy derivative, whereas 7-ketocholesterol was rather stable
Journal of Agricultural and Food Chemistry 05/2003; 51(8):2394-401. · 2.82 Impact Factor
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ABSTRACT: In this study the antioxidant activity of methanolic extracts of oregano and sage samples was tested. Samples of oregano belonged to Origanum onites and O indercedens species, whilst samples of sage belonged to Salvia officinalis and S fruticosa species. Two methods were used to evaluate the antioxidant activity of sage and oregano extracts: the crocin test and the Rancimat test. The methanolic extracts were also analysed by HPLC for the qualitative/quantitative determination of phenolic compounds. The total phenolic compound content of oregano samples showed no significant differences between the two species, but rosmarinic acid was present in higher amount in O indercedens. Carvacrol content sharply differentiated flowers from leaves. Samples of O indercedens had a higher antioxidant activity evaluated by the crocin test, whereas no differences were evidenced by the Rancimat test. For sage samples, carnosic acid and methyl carnosate showed a significant difference between the two species, with S fruticosa samples having a higher content than S officinalis samples. Samples of S fruticosa also had a higher antioxidant activity evaluated by the crocin test. The antioxidant activities of sage samples were, on average, higher than those of oregano samples. Some samples of sage had a very high antioxidant activity, with induction times more than 10-fold higher than that of lard used as the reference sample.© 2002 Society of Chemical Industry
Journal of the Science of Food and Agriculture 10/2002; 82(14):1645 - 1651. · 1.44 Impact Factor
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ABSTRACT: The 5α-hydroperoxides of β-sitosterol, campesterol, stigmasterol, and brassicasterol were obtained by photooxidation of the respective sterols in pyridine in the presence of hematoporphyrine as sensitizer. The reduction of the hydroperoxides gives the corresponding 5α-hydroxy derivatives. The 7α- and 7β-hydroperoxides of the sterols were obtained by allowing an aliquot of the 5α-hydroperoxides to isomerize to 7α-hydroperoxides, which in turn epimerize to 7β-hydroperoxides. The reduction gave the corresponding 7α- and 7β-hydroxy derivatives. The 5α-, 7α-, and 7β-hydroxy derivatives of β-sitosterol, campesterol, stigmasterol, and brassicasterol were identified by comparing thin-layer chromatography mobilities, specific color reactions, and mass spectral data with those of the corresponding hydroxy derivatives of cholesterol, which were synthesized in the same manner. The phytosterols had the same behavior to photooxidation as cholesterol and, moreover, the different phytosterols photooxidized at about the same rate. The mass spectra of the trimethylsilyl ethers of the hydroxy derivatives of the phytosterols investigated and of the corresponding hydroxy derivatives of cholesterol have the same fragmentation patterns and similar relative ion abundances. Keywords: Sterols; phytosterols; hydroxysterols; photooxidation; gas chromatography/mass spectrometry; GC/MS; mass spectra; trimethylsilyl ether
07/1999;
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ABSTRACT: The antioxidant capacity of the main phenolic compounds present in wood smoke and smoke flavourings used in the food industry was investigated by three methods, based on a kinetic and thermodynamic approach: the bleaching of the carotenoid crocin, the scavenging of the DPPH radical, and the determination of the oxidation potential. The reaction with the DPPH radical was evaluated calculating the effective concentration (EC50) and the antiradical efficiency (AE). The compounds tested were 2-methoxyphenols (guaiacol, 4-methylguaiacol, 4-ethylguaiacol, 4-vinylguaiacol, 4-propylguaiacol, eugenol, isoeugenol, vanillin, acetovanillone, 2-propiovanillone), 2,6-dimethoxyphenols (syringol, 4-methylsyringol, 4-allylsyringol, syringaldehyde, acetosyringone) and dihydroxybenzenes (catechol, 3-methylcatechol, 4-methylcatechol, 3-methoxycatechol and hydroquinone). The trend in antioxidant capacity was similar in all the three methods, with dihydroxybenzenes > 2,6-dimethoxyphenols > 2-methoxyphenols, although some discrepancies in the ranking within the groups were present. Considering the overall ranking, isoeugenol was amongst the most active compound, like dihydroxybenzenes, evidencing the role of a conjugated double bond at para position for the stabilization of the phenoxyl radical in the radical scavenging process.
Food Chemistry.
