Thermo-physical assessment of bread during staling (original) (raw)
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European Food Research and Technology, 2003
The usefulness of different bread improvers (aamylase, sourdough, k-carrageenan, hydroxypropylmethylcellulose) in an interrupted baking process was evaluated by using a differential scanning calorimeter as an oven. The thermal transitions of the wheat starch produced during the part-baking process, frozen storage at-18 C, finish baking and aging of the baked dough at 4 C were registered. The thermal properties of wheat starch during gelatinisation measured by differential scanning calorimetry were slightly affected by the dough formulation: only the peak temperature and the onset temperature underwent an increase, whereas the gelatinisation enthalpy decreased. The presence of the bread improvers minimised the negative effect of the frozen storage observed in the control sample, which showed an increase in the retrogradation temperature range. Concerning the aging of the baked dough after freezing and re-baking, all the improvers decreased the retrogradation enthalpy of the amylopectin, retarding the staling. Bread improvers can act effectively in the interrupted baking processes with frozen storage of the part-baked breads.
A Fresh Perspective on Staling: The Significance of Starch Recrystallization on the Firming of Bread
Journal of Food Science, 2002
Storage stability of standard white bread (SWB) and Meal, Ready-to-Eat (MRE) breads were studied in terms of texture firming, amylopectin recrystallization, and water relations. SWB showed a more rapid increase in firmness during storage mainly due to the loss of moisture to the crust and surrounding environment. The MRE, a long shelf-life military bread, firmed much slower due to the moisture loss inhibition (hermetic pouch) and plasticization (by formulation). This work confirmed previous findings that in some cases, firming of a bread can be strongly influenced by factors other than amylopectin crystallization. This is possible through controlling changes in the amorphous domains earlier described from thermomechanical studies.
3 Changes in Dough and Bread Structure as a Result of the Freezing Process
Advances in Heat Transfer Unit Operations: Baking and Freezing in Bread Making explains the latest understanding of heat transfer phenomena involved in the baking and freezing of bread and describes the most recent advanced techniques used to produce higher quality bread with a longer shelf life. Heat transfer phenomena occur during key bread-making stages (cold storage, resting, and fermentation) in which temperature and amount of heat transfer must be carefully controlled. This book combines the engineering and technological aspects of heat transfer operations and discusses how these operations interact with the bread making process; the book also discusses how baking and freezing influence the product quality. Divided into fourteen chapters, the book covers the basics of heat and mass transfer, fluid dynamics, and surface phenomena in bread-making industrial operations, mathematical modelling in porous systems, the estimation of thermo-physical properties related to bread making, design of equipment, and industrial applications.
Physico-chemical changes in breads from bake off technologies during storage
LWT - Food Science and Technology, 2011
Quality of several bread specialties from frozen partially baked breads was assessed to define main quality features. Loss of crust freshness shortly after baking was also determined. Quality parameters that characterize bread crust and crumb were determined by instrumental methods in nine different (regarding to formulation and bake off duration) bread types obtained from frozen partially baked breads. Principal component analysis (PCA) allowed discriminating among bread specialties. Quality parameters that enable the differentiation of wheat bread types were crust mechanical properties together with specific volume, crumb hardness and structure. Crust flaking barely represented a problem in the studied types of bread. Crust mechanical properties were rapidly lost during the first 4 hours after baking and the rate of the process was greatly dependent on the bread type. The force to promote crust fracture underwent increase up to 6 hours after baking and those changes occurred in the Aw range of 0.50-0.74 or moisture content 9-15g/100g.
Impact of baking conditions and storage temperature on staling of fully and part-baked Sangak bread
Journal of Cereal Science, 2014
The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
Effect of Carbon Dioxide Atmosphere on Staling and Water Relations in Bread
Journal of Food Science, 1990
The effect of Modified Atmosphere Packaging (MAP on staling and on water relations in bread was evaluated. Application of CO2 in MAP delayed staling of bread. Water sorption of bread packed in CO2 was reduced compared to fresh bread and to bread packed in air. A water activity of 0.75 was found to be the boundary between the multilayer and the free water range of the isotherm. Spoilage of bread (microbial growth and staling) took place only above this water activity. Inverse Gas Chromatography was found to be unsuitable for investigating the effect of CO2 on bread at the higher water activities because equilibrium conditions could not be achieved at these water activities. day up to one month (Avital and Mannheim, 1988). Daniels et al. (1985) reviewed several mechanisms explaining the effect of COz on microbial growth. None of these mechanisms can fully explain the bacteriostatic effect of CO,. Staling, which is generally associated with starch crystallization, remains the main shelf-life limiting factor for bakery products stored in MAP (Kulp and Ponte, 1981). Some findings imply that water relations in bread are involved in staling and can be summarized as follows: (1) Retrogradation of starch occurred only above a moisture content of 16.4% (Knightly, 1968); (2) Bread with a moisture content higher than in a commercial product (38% on wet basis), remained fresher for a longer period (Maleki et al., 1980); (3) Loss of 2% moisture was equal to one day of shelf-life (Bechtel and Meisner, 1954); (4) Moisture migrated during storage from crumb to crust (Pisesookbunterng and D'Appolonia, 1983), and within bread constituents (Kulp and Ponte, 1981). Wilhoft (1971) claimed that the migration of water was from gluten to starch; (5) A correlation between bread staling and decrease in water mobility was found by Leung et al. (1983) using NMR. One of the methods for following bread staling is to measure firmness and compressibility of the bread. Many variations of this test, using a Universal Testing Machine (UTM), have been reported (
Thermophysical properties evolution of French partly baked bread during freezing
Food Research International, 2004
Few data are available on the thermophysical properties of the frozen partly baked breads. In this paper, thermophysical properties, including apparent and true densities, specific heat, enthalpy and effective thermal conductivity were determined separately for crumb and crust of partly baked bread. Total enthalpy of fusion, unfrozen water and solid specific heat were determined by differential scanning calorimetry. The apparent specific heats were estimated in base of the unfrozen water at )40°C and initial freezing point. The effective thermal conductivity was measured with a line source probe in the range )35 to 25°C. Four predictive models of the effective thermal conductivity of porous food were developed (parallel, series, Krischer and Maxwell models). The effective thermal conductivity predicted by Krischer model was in good agreement with the experimental data.
Assessment of textural changes in sliced pan bread on aging using sensory and instrumental methods
Journal of Food Processing and Preservation, 2019
Staling is an issue of great concern regarding the quality life of bread since it reduces quite rapidly, its acceptability by the consumers. Numerous studies have been reported in literature about bread staling speculating the possible mechanisms and the various factors which govern its development. Many ingredients such as starch and other carbohydrates (sugars, hemicelluloses, and pentosans), proteins, hydrocolloids, lipids and shortenings, enzymes, sourdough etc., had been implicated to affect the process of staling (Gray & Bemiller, 2003). Nevertheless, staling mechanism is still far from being elucidated, despite the fact that it has been studied by a number of techniques such as thermal analysis, rheological methods, X-ray crystallography, NMR spectroscopy, IR spectroscopy, colorimetry, and electrical impedance (Fadda, Sanguinetti, Del Caro, Collar, & Piga, 2014). Staling has been investigated in model systems as
Effect of Final Dough Temperature on the Microstructure of Frozen Bread Dough
Journal of Cereal Science, 2002
The effect of final mixing temperature (16°C and 31°C) on the structure stability of frozen bread dough was examined by low temperature-scanning electron microscopy and the quality of bread made from them assessed. The presence of ice-crystals were determined in both doughs after freezing, by low-temperature S.E.M. The microstructures showed a slight increase in size and decrease in number of angular voids, representing ice-crystals, after 14 weeks storage at −20°C. Loaves baked from frozen dough with a final mixing temperature of 31°C were poorer in both gassing power and overall loaf quality than 16°C doughs, after 14 weeks storage. 2002 Elsevier Science Ltd Keywords: frozen dough, low temperature-scanning electron microscopy. lower final dough temperature is necessary for the : LT-SEM=low temperature-scancooler ambient temperatures. In addition, the ning electron microscopy; RACI=Royal Australian lower temperatures may compromise occupational Chemical Institute; HDPE=high density polyethylene;