影响面包老化因素研究进展

该文综述近年来国内外对面包老化研究成果,从水分、淀粉酶、添加剂、起酥油、贮存和温度等方面论述抑制面包老化方法,以期能对面包行业具有一定理论指导作用。     

面包老化机理及延缓老化方法的研究进展

面包老化一直以来是一个难以解决的难题,给生产和消费带来极大的损失,因此,研究面包老化机理有着重要的意义.综述了国内外近年来研究成果,从面包老化的内因和外因两方面详细论述了面包老化的机理.并提出了延缓面包老化的方法.     

面包老化作用的研究进展——老化机理探讨

对面包贮存过程中 ,面包内水分、淀粉、面筋蛋白所发生的变化及其相互作用进行了较详细的综述 ,并阐述了水分迁移、淀粉重结晶、淀粉与蛋白质的交互作用引起面包老化的机理     

面包老化抑制因素的研究

在西方国家，面包是餐桌上的主食，面包的质量与人们的健康和幸福息息相关。随着经济水平的提高，面包已经悄悄走进了我们的生活。但是，老化的面包口感差，易掉屑且香味丧失，不为广大消费者所接受。我们需要研究面包老化的机理，并从理论上寻找抑制面包老化的方法，提高面包的质量。本文综述了近年来国内外对面包老化的研究结果，从水分、淀粉结晶、添加剂、淀粉酶、贮存和温度几方面论述了抑制面包老化的方法。并对抑制面包老化，全面提高面包质量的研究趋势进行了展望。     

影响面包老化的因素

证据表明许多因素影响面包的老化，其中包括面包的水分，不同来源的α－淀粉酶，起酥油，表面活性剂，面包的贮藏温度，蛋白质含量等。     

面包老化抑制因素研究

随着经济水平提高,面包已悄悄走进我们的生活;但是,老化面包口感差,易掉屑且香味丧失,不为广大消费者所接受。为此,需要究面包老化机理,并从理论上寻找抑制面包老化方法,提高面包质量。该文综述近年来国内外对面包老化研究成果,从水分、淀粉结晶、添加剂、淀粉酶、贮存和温度几方面论述抑制面包老化方法;并对抑制面包老化,全面提高面包质量研究趋势进行展望。     

面包老化抑制因素的研究

在西方国家,面包是餐桌上的主食,面包的质量与人们的健康和幸福息息相关.随着经济水平的提高,面包已经悄悄走进了我们的生活.但是,老化的面包口感差,易掉屑且香味丧失,不为广大消费者所接受.我们需要研究面包老化的机理,并从理论上寻找抑制面包老化的方法,提高面包的质量.本文综述了近年来国内外对面包老化的研究结果,从水分、淀粉结晶、添加剂、淀粉酶、贮存和温度几方面论述了抑制面包老化的方法.并对抑制面包老化,全面提高面包质量的研究趋势进行了展望.     

影响面包老化因素及抗老化途径

该文综述近年来国内外有关面包老化研究成果,介绍影响面包老化主要因素,并从改变原辅料、添加酶制剂、乳化剂和亲水性胶体等方面论述抑制面包老化方法。     

Effect of staling on viscoelastic properties of pastes prepared from arabic bread

Dynamic testing detected differences in the rheological properties of pastes prepared from progressively aged Arabic bread. The storage (G') and loss (G″) modulii decreased at different rates upon storage. The progress of textural changes responsible for the generation of the sensory ‘stale’ response was marked by the transition of Arabic bread pastes from viscoelastic solids (G′>G″) to elastoviscous liquids (G″>G′).     

Influence of inulin on physical characteristics and staling rate of gluten-free bread

Inulin preparations with different degree of polymerization (HSI with a DP < 10, GR − DP ? 10 and HPX − DP > 23) were used for the production of gluten-free bread. It was found that an addition of investigated compounds resulted in an increase of loaf volume and reduction of crumb hardness. However, internal structure of the obtained loaves was less uniform and more open than in control bread. Generally, inulin preparations with lower degree of polymerization had stronger effect on all analyzed parameters than that with higher DP. A decrease in staling was observed (measured as the rate of crumb hardening), which was caused by the presence of inulin. The highest content of retrograded amylopectin was found for crumb with HSI, and the lowest for samples with HPX.     

Effect of fermentation conditions on bread staling kinetics

The effects of yeast dose, temperature and fermentation time on bread volume, bread density, bread texture (firmness, cohesiveness, resilience, springiness and gumminess) and their change during staling were analysed. Thus, changes in the texture profile (TP) parameters as bread aged were modelled and their initial values and their variation rate were obtained. In white and whole breads, the longer the fermentation time and the higher the yeast dose, the lower the firmness and the firming rate. The fermentation temperature only affected the initial firmness in whole breads. Significant linear correlations were found between bread density and volume (r ² = 0.94 in white bread; r ² = 0.96 in whole bread), between density and the initial firmness (r ² = 0.88 in white bread; r ² = 0.61 in whole bread), and between the first two parameters and the firming rate. Between density and firming rate r ² obtained was 0.72 in white bread and 0.32 in whole bread and between volume and firming rate r ² obtained was 0.58 in white bread and 0.29 in whole bread.     

Water molecular dynamics during bread staling by Nuclear Magnetic Resonance

Bread staling is a complex phenomenon that originates from multiple physico-chemical events (amylopectin retrogradation, water loss and redistribution) that are not yet completely elucidated. Molecular properties of white bread loaves were characterized by multiple proton Nuclear Magnetic Resonance (NMR) techniques (proton FID, T₂ and T₁ relaxation time) over 14 days of storage. Changes at a molecular level (faster decay of proton FIDs and shifting of proton T₂ relaxation times distributions towards shorter times), indicating a proton mobility reduction of the bread matrix, were observed during storage. Multiple ¹H T₂ populations were observed and tentatively associated to water-gluten and water-starch domains. Proton T₁ of bread was for the first time measured at variable frequencies (Fast Field Cycling NMR) and found to be strongly dependent upon frequency and to decrease in bread during storage, especially at frequencies ≤ 0.2 MHz. An additional proton T₁ population, relaxing at 2 ms, was detected at 0.52 MHz only at early storage times and tentatively attributed to a water-gluten domain that lost mobility during storage.     

Methodological developments in bread staling assessment: application to enzyme-supplemented brown pan bread

In this study, texture profile analysis (TPA) at 40 and 80% compression and a newly proposed penetration test were used to evaluate the effects of amylolytic and non-amylolytic enzymes on the textural properties of fresh and stored brown pan breads. The correlations between instrumental parameters and sensory attribute results obtained by a trained panel of assessors were also investigated. Comparison of the results obtained through TPA at the two compression rates was very useful, as the 40% compression TPA hardly reflected the changes that took place in the enzyme-supplemented bread samples over a storage time of 20 days. The penetration curve profiles provided very valuable information, which complemented the TPA for the purposes of assessing bread ageing and the effect of adding enzymes.     

Thermo-physical assessment of bread during staling

Staling of bread is a highly complex phenomenon that is not yet fully understood. This study examined the effect of staling on thermal (DSC) and thermo-physical (DMA) properties of bread. The staling process increased water migration from the crumb to the crust and increased unfreezable water (UFW) fraction. Amylopectin retrogradation incremented during bread staling, and it was showed that the loss in freezable water (FW) was caused from water incorporation into the starch crystalline structure and water migration from the crumb to the crust. DMA was able to follow the shrinking behavior of bread crumb during freezing. Crumb shrank through the entire cooling and freezing process. The matrix shifts through their freezing process incremented the rate of their contraction, probably due to the matrix dehydration as consequence of ice formation. The ageing process changes the thermo-mechanical profile of the crumb, and it was showed that a greater amount of retrogradated starch, affected significantly the contraction capacity of bread crumb.     

Effect of damaged starch levels on flour-thermal behaviour and bread staling

The effect of the amount of damaged starch in two different flours (wheat and triticale) on the bread quality and its behaviour during storage has been analysed. Two wheat and one triticale flour cultivars were milled in a disc mill to obtain different levels of damaged starch. Differential Scanning Calorimetry (DSC) and Rapid Visco Analyser (RVA) were used to characterize the flour properties and TA-XT2 textural analyses were made on breadcrumb. The effect of the damaged starch content on the bread firming, the amylopectin retrogradation and starch-pasting properties were studied in order to establish any relationship between damaged starch and bread staling. DSC analysis showed that the damaged starch content changed the thermal behaviour of flour–water mixtures: the higher the levels of damaged starch the lower the starch-gelatinization enthalpy and the higher the melting enthalpy of amylose–lipid complexes. The amount of amylopectin retrogradation and breadcrumb firming increased with the damaged starch content at the beginning of storage time; however, differences were decreasing at final storage time. The flour viscosity during pasting decreased as their damaged starch content increased.     

The staling of bread: an X-ray diffraction study

Bread crumb X-ray patterns were analysed by different methods, the objective being to provide more in-depth knowledge of the relationships among starch crystallinity, amylopectin retrogradation and bread firming. Both crumb-firming and amylopectin retrogradation increased with storage time. However, total mass crystallinity grade and relative crystallinity increased only in the first 24 h. The determination of starch crystallinity requires the separation of the crystalline and amorphous intensities, which is sometimes arbitrary, so it would be useful to improve this methodology. Different methods used to determine total crystallinity grade only show the differences existing between fresh and stored bread. B-type crystal structure—corresponding to the amylopectin retrogradation—increased during bread storage, showing a high correlation with bread-firming and storage time. This fact emphasized the above results and suggested that amylopectin retrogradation is an important component to the elucidation of bread staling.