| 1. |
- Ahrné, Lilia, et al.
(author)
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Effect of crust temperature and water content on acrylamide formation during baking of white bread : Steam and falling temperature baking
- 2007
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In: Lebensmittel-Wissenschaft + Technologie. - : Elsevier BV. - 0023-6438 .- 1096-1127. ; 40:10, s. 1708-1715
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Journal article (peer-reviewed)abstract
- The effect of crust temperature and water content on acrylamide formation was studied during the baking of white bread. To assess the effect of over-baking, we used a full factorial experimental design in which the baking time was increased by 5 and 10 min at each baking temperature. Additional experiments were performed with steam baking and falling temperature baking. Immediately after baking, the crust was divided into the outer and inner crust fractions, and the water content and acrylamide concentration of each fraction was measured. The outer crust had a significantly lower water content and higher acrylamide concentration than the inner crust did. Crust temperature in combination with water content had a significant effect on acrylamide formation, higher temperatures resulting in higher acrylamide concentrations. However, at very high temperatures and lower water contents, acrylamide concentration was observed to decrease, though the bread colour was then unacceptable for consumption. Steam and falling temperature baking, on the other hand, decreased the acrylamide content while producing bread crust with an acceptable colour. The lowest acrylamide values and an acceptable crust colour were produced by steam baking. © 2007 Swiss Society of Food Science and Technology.
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| 2. |
- Andersson, Karin, et al.
(author)
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Influence of oxygen and copper concentration on lipid oxidation in rapeseed oil
- 1998
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In: Journal of the American Oil Chemists Society. - 0003-021X .- 1558-9331. ; 75:8, s. 1041-1046
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Journal article (peer-reviewed)abstract
- The influence of oxygen concentration and copper on lipid oxidation in rapeseed oil during storage at 40°C was investigated. The oil was stored in air, or with 1.1%, 0.17%, or 0.04% oxygen in the headspace, and 70 or 0.07 ppm copper was added. Volatile oxidation products and oxygen consumption were monitored. Addition of 70 ppm copper to the sample in air resulted in a 70-fold higher hexanal concentration after 35 d of storage, compared to the sample without added copper. The addition of 0.07 ppm copper to the sample stored in air gave a doubled hexanal concentration, compared to the sample without copper, after 35 d of storage. For the samples with 70 ppm copper at 0.17% and 0.04% oxygen, all oxygen was consumed after 7 d of storage. The results show the importance of minimizing the oxygen available for oxidation, especially when pro-oxidants are present. In the sample with 70 ppm added copper, in air, the hexanal increase was 65 times larger than for the same sample in 0.04% oxygen. A comparison of the effect of oxygen or copper on oxidation shows that the addition of 70 ppm copper to the 0.04% oxygen sample gave the same increase in hexanal content as an oxygen increase to 0.17%.
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| 3. |
- Andersson, Karin, et al.
(author)
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Influence of oxygen concentration and light on the oxidative stability of cream powder
- 1998
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In: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 31:2, s. 169-176
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Journal article (peer-reviewed)abstract
- The production of volatile oxidation products and consumption of oxygen were measured in cream powder stored for 35 weeks at 30 °C in darkness or exposed to fluorescent light. The headspace of the bottles contained either air (209 mL O 2/L) or 13, 3.5, 0.4 or 0.3 mL/L oxygen in nitrogen. The exposure to light strongly influenced both the rate of hexanal production and oxygen consumption. After the first 5 weeks of storage in light, significantly different oxygen-dependent increases in hexanal were found for all samples. Although the samples stored in darkness showed a much smaller hexanal increase, it was still significant during storage. After 35 weeks of storage, the dark-stored sample in air showed a highly significant larger hexanal increase than all the other samples stored in darkness, but after the same storage period, the hexanal increase in the 13, 3.6 and 0.4 mL O 2/L samples was the same. The production of the Strecker aldehyde, 3-methylbutanal, was found to depend on light and to some extent on oxygen concentration, which indicates that lipid oxidation also influenced the conditions of the Maillard reaction. © 1998 Academic Press Limited.
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| 4. |
- Andersson, Karin, et al.
(author)
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Influence of oxygen concentration on the flavour and chemical stability of cream powder
- 1998
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In: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 31:3, s. 245-251
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Journal article (peer-reviewed)abstract
- Descriptive sensory analysis and analysis of hexanal content were performed on cream powder stored in darkness at different oxygen concentrations at 30 °C for up to 45 weeks. The headspace of the samples contained 209 (air), 13, 3.6, 0.4 or 0.3 m/L oxygen/L headspace gas. All samples stored with reduced oxygen content were, with one exception, significantly different from the air-packed sample after 25 as well as after 45 weeks of storage, both in their hexanal concentration and according to sensory analysis. However, there were no significant sensory differences between the samples stored with reduced oxygen for 25 or 45 weeks. Analysis of the hexanal concentration in the samples was a more sensitive method than sensory analysis for detecting differences between samples stored for the same length of time. Furthermore, some of the samples with reduced oxygen concentration were found to differ significantly in their hexanal concentration. Significant differences between samples before storage and samples stored for 25 or 45 weeks, regardless of oxygen concentration, were found by both sensory and chemical analyses. © 1998 Academic Press.
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| 5. |
- Andersson, Karin, et al.
(author)
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Influence of oxygen concentration on the storage stability of cream powder
- 1997
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In: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 30:2, s. 147-154
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Journal article (peer-reviewed)abstract
- The influence of low oxygen concentrations on lipid oxidation during storage of cream powder was studied. The powder was packed with oxygen concentrations of 209 mL/L, 17 mL/L, 8.3 mL/L, 3.4 mL/L, 1.5 mL/L, 0.7 mL/L and 0.6 mL/L and stored in darkness at 30°C for 29 weeks. To follow oxidation, the formation of volatile oxidation products and oxygen consumption were measured. After 7 weeks of storage a significant (P <0.01) hexanal development was already seen in all the samples, and the hexanal content was directly related to the initial oxygen content, with one exception, the 0.6 mL/L sample, which had a slightly (but not significantly, P >0.05) higher hexanal content than the 0.7 mL/L sample. There were only small differences in hexanal formation between the samples packed with oxygen concentrations below 3.4 mL/L. This could be due to a more pronounced influence of oxygen diffusion at these low levels of oxygen, leading to a diffusion-controlled oxidation. Other volatiles, not produced by lipid oxidation, also increased during storage. The formation of Strecker aldehydes was found to be oxygen-dependent, whereas the formation of 2-alkanones was not. Measurement of oxygen consumption was not sufficient to detect differences in oxidation rate between the samples packed with 17 mL/L oxygen and less. © 1997 Academic Press Limited.
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| 6. |
- Andersson, Karin, et al.
(author)
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Kinetic studies of oxygen dependence during initial lipid oxidation in rapeseed oil
- 1999
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In: Journal of Food Science. - 0022-1147 .- 1750-3841. ; 64:2, s. 262-266
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Journal article (peer-reviewed)abstract
- Lipid oxidation was studied in rapeseed oil, stored at 35 or 50°C in 0.03, 0.3, 1.0 or 1.8% oxygen for 42 days. Peroxide value (PV), oxygen consumption, tocopherol consumption and production of volatile compounds were analyzed to follow the oxidation. At 50°C, lipid oxidation measured as oxygen consumption or PV was only slightly influenced by oxygen concentration ?1%. Below 0.5% the influence was strongly enhanced. The production of volatiles showed different relationships to oxygen concentration and some compounds were produced in larger amounts at lower O2, than at higher O2 concentrations.
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| 7. |
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| 8. |
- Ekstrand, Bo, et al.
(author)
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Lipase Activity and Development of Rancidity in Oats and Oat Products Related to Heat Treatment during Processing
- 1993
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In: Journal of Cereal Science. - : Elsevier BV. - 0733-5210 .- 1095-9963. ; 17:3, s. 247-254
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Journal article (peer-reviewed)abstract
- A pilot plant process simulation of dry and wet hydrothermic treatment of oats was performed in order to study the effect of the different process steps on lipase activity and the storage stability of the fat phase. A comparison was made between oats that had passed through a dry kiln treatment prior to steam preparation and oats that had only been steam-treated. Samples were taken after step in the process as well as during storage at +30°C for up to 44 weeks. The lipase activity disappeared after steam preparation, but not after the dry-heat treatment used in this process experiment. The fat phase was analysed with regard to the amount of free fatty acids (FFA) and the content of individual fatty acids. The initial content of FFA was about 8-9%. The hydrolysis of fat, giving an increase in the amount of FFA, took place in all the stored samples, but was much more pronounced in the samples that had not undergone dry- heat treatment. In the dry-heat-treated samples, the FFA concentration reached a maximum at 13-15% after 16 weeks of storage. In the samples that had not been dry- heat-treated, the FFA reached over 30% in whole oat grains after 16 weeks of storage and continued to increased to over 40% after 30 weeks of storage. In the flour the FFA concentration was lower than in whole grains. Unexpectedly, lipolysis in this case was more pronounced in the whole kernels than in the flour samples. Lipolysis was not related to the measured remaining lipase activity. Head-space analyses of hexanal indicated that the formation of volatile lipid oxidation products was dependent on the process design, but the hexanal concentration was not related to the amount of FFA.
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| 10. |
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