| 1. |
- Chen, Guo, 1969, et al.
(författare)
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A Porosimetric Mapping of Breadcrumb Structures by Differential Scanning Calorimetry and Nuclear Magnetic Resonance
- 2013
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Ingår i: Food Biophysics. - : Springer Science and Business Media LLC. - 1557-1858 .- 1557-1866. ; 8:3, s. 209-215
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Tidskriftsartikel (refereegranskat)abstract
- Ice crystals in frozen bread are substantially shaped by the complex pore structures of crumb. In this study we inspected the breadcrumb porosity of ice-filled pores from the profiles of ice crystals mapped by differential scanning calorimetry and nuclear magnetic resonance. Two types of wheat bread containing different amounts of dietary fiber and sugar were studied after frozen storage at -18 A degrees C for 3 weeks. Both pore sizes and pore size distributions were derived via comparing the measurements to those of water-saturated mesoporous silica (MCM-41 C18) with a well-defined pore size distribution. Good consistency was shown for the crumb pore structures obtained using the two techniques. Both bread types featured broad nanometer ranges of pore sizes characterized with largely bimodal size distributions. Besides, the frozen high-fiber bread displayed a higher proportion of large pores and a broader pore size distribution than the high-sugar bread. By comparing such pore size distributions with those obtained previously for the corresponding fresh bread, it can be concluded that structural differences between the two bread types were produced during the frozen storage, manifesting the disparate freezing performances of bread with different formulations.
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| 2. |
- Chen, Guo, 1969, et al.
(författare)
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Impact of long-term frozen storage on the dynamics of water and ice in wheat bread
- 2013
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Ingår i: Journal of Cereal Science. - : Elsevier BV. - 0733-5210 .- 1095-9963. ; 57:1, s. 120-124
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Tidskriftsartikel (refereegranskat)abstract
- Frozen storage of bread has a substantial impact on the dynamics of water and ice in the crumb and crust. In this study, the impact was characterized using wheat bread stored at -18 °C for a long term of ?4 months. The frozen bread incurred a considerable loss of the crumb water that migrated out and formed ice crystals on the bread surface. Such a moisture decrease underwent more rapidly for the bread stored without intact crust, suggesting the specific role of crust during frozen storage. Moisture also redistributed significantly within the frozen crumb, resulting in an elevated crumb heterogeneity of freezable water. This redistribution of freezable water was accompanied by a progressive recrystallization of the crumb-borne ice crystals, which were measured to grow into bulk sizes using a modified calorimetric procedure for analyzing the crumb samples at their as-frozen states.
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| 3. |
- Eckardt, Johanna, et al.
(författare)
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Long-term frozen storage of wheat bread and dough : Effect of time, temperature and fibre on sensory quality, microstructure and state of water
- 2013
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Ingår i: Journal of Cereal Science. - : Elsevier BV. - 0733-5210 .- 1095-9963. ; 57:1, s. 125-133
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to determine effect of storage time, storage temperature and addition of fibre on sensory quality, state of water, microstructure and texture of bread and dough. Samples with and without fibre, were stored frozen for 2, 3.5 and 6 months at temperatures of -19, -16 and -8 °C as dough and bread. Sensory quality was evaluated by a trained analytical panel. Microstructure was analysed by light microscopy. Texture measurements were performed on bread, and the state of water was measured by differential scanning calorimetry. Bread without fibre stored as dough at -19 °C was the sample most like freshly baked bread. Sensory evaluation also confirmed that quality of the final bread was improved if samples were stored as dough compared to stored as bread. The microstructure had larger gaps between the starch and gluten phases when stored at warmer temperatures, due to retrogradation of starch, dehydration of gluten and water migration. DSC measurements showed that bread stored at -19 °C gained extra amount of freezable water, but lost ice after storage at -8 °C. Texture measurements showed that firmness increased with extended storage time. Bread stored at -8 °C had lowest quality in all measurements.
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