Waxy durum and fat differ in their actions as improvers of bread quality

Fat is commonly added to bakery products to improve eating qualities and extend shelf life. Flour milled from waxy durum grain was incorporated into bread formulations and its effects on crumb softness and loaf volume compared to those of added fat. Low levels of fat (0.1-0.3% of flour weight) softened the bread crumb and increased loaf volume. Most of the softening effects were evident in the crown of the loaves protruding above the tin and a high proportion of the reduction in compression was associated with increased volume. Loaves baked with waxy durum flour were softer than those baked with fat and the softening effects were evident both in the crown of the loaf and at its base where it had been confined within the tin. Waxy durum flour reduces compression independently of increased volume. It is suggested waxy durum flour acts by slowing the migration of water from the gluten phase to the starch phase so maintaining the level of mobile water in the gluten where it acts as a plasticiser. Independent organoleptic assessment of bread quality baked with combinations of waxy durum and fat confirmed the quality enhancing effects of waxy durum flour.     

The effect of chitosan oligosaccharides on bread staling

The aim of this work was to investigate the effects of chitosan oligosaccharides and chitosan on the rate of staling and properties of bread crumb and crust. Rates of crumb firming varied with storage time. The possible mechanisms including prevention of amylose–lipid complexation, acceleration of dehydration from both starch and gluten, adsorption of chitosan onto the starch surface and increase of moisture migration rate from crumb to crust are proposed and analysed. Chitosan oligosaccharides and low molecular weight chitosan increase bread crumb staling rate to a much lesser extent than does middle molecular weight chitosan.     

温度对马铃薯α淀粉老化的影响

采用挤压膨化技术制作马铃薯α淀粉,并利用酶水解法及X-射线衍射法等研究了在同一贮藏时间内,不同贮藏温度对膨化马铃薯α淀粉老化变化的影响,探讨了影响机理。研究结果表明,贮藏温度从23℃±1℃降低到-18℃±1℃时,贮藏期为180d的样品α度也从87.8%明显降低到80.2%,样品的结晶度从8.4%上升为16.45%;说明样品α度的高低与贮藏温度的高低成正比,而样品的老化程度高低与贮藏温度的高低成反比。     

亲水胶体抗馒头老化效果的研究

馒头的老化是制约馒头工业化进程的一个关键问题。采用单因素试验和正交试验,研究3种亲水胶体(黄原胶、海藻酸钠、卡拉胶)对馒头制品在温度4℃贮存下的抗老化效果。试验结果表明,黄原胶、海藻酸钠和卡拉胶对馒头均有一定的抗老化效果。通过正交试验,得到抗馒头老化效果较好的3种胶体复配比例为:黄原胶添加量为0.15%,海藻酸钠添加量为0.05%,卡拉胶添加量为0.15%。     

大豆粉末磷脂对馒头及老化品质影响研究

本文探讨将大豆粉末磷脂加入金苑面粉和雪燕面粉中,研究其封馒头及老化品质的影响。结果表明,金苑面粉和雪燕面粉的大豆粉末磷脂最佳添加量均为0．6％,金苑馒头和雪燕馒头的体积比空白分别增加了4．0％和3．0％,总评分比空白提高约10分,48h时馒头的硬度减少35．0％和34．1％,和24h时空白馒头的硬度相近,弹性和1h时空白馒头的相近,对馒头老化起到了显着的延缓作用。     

Effect of glutathione on wheat dough properties and bread quality

Reduced glutathione (GSH), released from lysed yeast cells, is well-known for weakening dough structure. However, its influence on bread texture and staling has not yet been completely elucidated. Herein, this study aims at assessing the effects of GSH on dough properties and bread quality, especially bread staling, using Rheofermentometer analysis, texture profile analysis (TPA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and low-field nuclear magnetic resonance (LF-NMR). The results revealed that GSH substantially decreased the dough height and gas-retention capacity during fermentation. The weakened dough structure was attributed to GSH-induced disulfide bond cleavage in gluten proteins and the depolymerization of glutenin polymers. The addition of 0.005%–0.01% GSH resulted in acceptable bread quality. However, bread supplemented with 0.015%–0.03% of GSH exhibited a coarser and more open crumb microstructure, as well as high level of hardness and low resilience during aging. GSH promoted crumb water loss and drove the water shift from the immobilized to the bound state. The DSC and XRD analyses further confirmed that GSH promoted starch retrogradation and recrystallization. These results suggest that apart from the gluten structure, GSH also altered gluten−starch interactions and water redistribution, ultimately decreasing bread quality and accelerating bread staling.     

Monitoring the staling of wheat bread using 2D MIR-NIR correlation spectroscopy

Staling of bread is a major source of food waste and efficient monitoring of it can help the food industry in the development of anti-staling recipes. While the staling fingerprint in the mid-infrared region is fairly well established this paper set out to find the most informative parts of the near-infrared spectra with respect to staling. For this purpose, two-dimensional correlation spectroscopy on near- and mid-infrared spectra of wheat bread crumb during aging was employed for the first time. The important mid-infrared absorption band at 1047 cm⁻¹ related to amylopectin retrogradation was found to correlate positively with increased bread hardness and to co-vary with the near-infrared band at 910 nm in the short wavelength region (r² = 0.88 to hardness), the near-infrared band at 1688 nm in the 1. overtone region (r² = 0.97 to hardness) and to the near-infrared band in the long wavelength region at 2288 nm (r² = 0.97 to hardness). The spectral information from the first principal component on near-infrared and the first principal component on mid-infrared was found to be highly correlated by a r² = 0.98. It is demonstrated that the major bread staling processes such as amylopectin retrogradation and water loss can be followed with both near- and mid-infrared spectroscopy.     

黑豆面包的研制及其质构特性的研究

通过向面粉中添加不同比例的黑豆粉,利用质构仪测定在不同储藏时间下,面包质构特性的变化趋势,发现添加5%黑豆粉末的面包,在硬度、弹性、咀嚼性3个方面都有很好改善,不但增强了面包的营养价值,而且还具有良好的保藏性能,使货架期更长。     

单甘酯在板栗面包中的应用研究

通过单因素实验,探讨了单甘酯对板栗面包焙烤品质、面包贮存过程中老化指标的影响,实验结果表明:单甘酯的添加对板栗面包的焙烤品质及老化指标的影响显著。当单甘酯添加量为0.3%时,板栗面包具有良好的焙烤品质;在贮存5d后,板栗面包的失水速率明显减慢;在贮存7d后,面包芯硬度比对照组面包减少34%,板栗面包的老化速度减缓。     

Properties of bread made from frozen dough containing waxy wheat flour

The quality of bread made from frozen dough is diminished, and staling rate is increased by changes that occur during freezing and storage. New cultivars of waxy wheat flour (WWF), containing higher levels of amylopectin, may help improve the quality of baked products. Bread quality and staling were investigated for bread containing 0–45% WWF and 55–65% water after freezing and 90-day frozen storage. The specific volume was highest with 15% WWF substitution and 60% water in bread made from both unfrozen and frozen dough. With higher levels of WWF and lower water content, bread staling rates decreased. Bread with higher levels of WWF were darker and had greater color variation. ¹H NMR studies showed that bread with greater WWF and water had higher transverse relaxation (T₂) times (9–11 ms), but less change in T₂ during storage. This research demonstrated that specific combinations of WWF and water produced a better quality of bread after dough freezing.