Physicochemical property changes in germinated brown rice flour from different storage periods of paddy rice

This study revealed that the storage duration (2, 4, 6, 8, 10 and 12 months) of paddy rice and pH (3 and 6.8) of steeping water during germination were significantly influenced the physicochemical properties of germinated brown rice flour (GBRF). GBRF obtained at pH 3 vs. 6.8 provided the highest both reducing sugar content and free gamma‐aminobutyric acid (GABA) content (99.8 vs. 54.2 mg per 100 g flour respectively) as the paddy rice was stored for 8 months. The peak viscosity of GBRF obtained at pH 3 and 6.8 exhibited the lower values than that of non‐GBRF throughout the storage. From the principal component analysis, reducing sugar had a positive correlation with α‐amylase activity whereas a negative correlation was found with peak viscosity. GBRF from paddy rice stored for 8 months and germinated at pH 3 possessed the highest free GABA content, 50 times of the non‐GBRF, which can be further utilised in functional and healthy foods.     

Rheological properties of wheat flour and quality characteristics of pan bread as modified by partial additions of wheat bran or whole grain wheat flour

The use of bran and whole grain flour changes dough rheology and causes difficulties in manufacturing bakery products. The aim of this study was to analyse the influence of substituting refined wheat flour (WF) by wheat bran (WB; 5%, 10%, 20%, 30% and 40%) or whole grain wheat flour (WGWF; 10%, 20%, 30%, 40% and 50%) on dough rheological properties and pan bread quality characteristics. The addition of WB and WGWF increased water absorption and resistance to extension and decreased stability, extensibility and peak viscosity. Effects with WB were more pronounced. The presence of WB or WGWF increased crumb moisture content, firmness and hardness and decreased specific volume of pan bread. It is important to set new farinographic and extensographic standards when using WB and WGWF, allowing for a correct correlation between rheology and quality characteristics of bakery products, as the same standards used for WF are not valid.     

A PNA-array platform for the detection of hidden allergens in foodstuffs

A duplex PCR method was developed to simultaneously detect the presence of hazelnut and peanut in raw materials and commercial products. It was found to be able to specifically detect traces of the investigated products down to 50 pg of their target DNA.A PNA array device has been designed and implemented to be used in combination with the duplex PCR in order to investigate the presence of traces of potentially allergenic nuts in foodstuffs. A PNA probe for each target amplified by the duplex PCR was designed, synthesized and characterized. The PNA probes were then deposited on commercial slides in order to build a PNA array to be used for recognizing the PCR products; the concentration of the probes as function of the concentration of the target DNA, together with the specificity of the probes were investigated.The conditions optimized during the setting of the experiment were used to obtain the final version of the PNA array which was then used to test several commercially available foodstuffs claiming to contain or not to contain the targeted nuts.     

高筋粉添加量对复配粉的糊化特性及面团流变学特性的影响

为了改善市售小麦粉(蛋白质10.3%)制作油塔子的面团特性,在市售小麦面粉(以下简称小麦粉)中添加不同比例高筋粉(蛋白质12%),测定复配粉的基本性质、糊化特性以及面团流变学特性。结果表明,随着高筋粉添加量增加,复配粉的白度显著增加(p0.05),蛋白质干基、湿面筋含量和水分均呈上升趋势,灰分变化并不显著(p0.05);复配粉的峰值黏度、最低黏度、最终黏度随着高筋粉添加量的增加而下降,在高筋粉添加量为40%时,衰减值及回升值均达到最低,为850.50 cp、1035.50 cp;添加高筋粉降低了小麦粉的面团形成时间和稳定时间,弱化程度反而升高;高筋粉添加量为40%时,复配粉的拉伸曲线面积、拉伸阻力、延伸度均为最高,分别是122.05 cm2、341.75 BU、179.30 mm。结论说明高筋粉对市售面粉粉质特性、糊化特性、面团拉伸特性均有影响,制作油塔子面团高筋粉的添加量以40%为宜。     

芽麦粉添加量对中筋粉面团特性的影响

本文以中筋面粉为原料,分别添加5%、10%、15%、20%和25%的芽麦粉(SWF),利用快速黏度分析仪、粉质仪和拉伸仪分析了芽麦粉添加量对中筋粉面团特性的影响。结果表明,芽麦粉的添加使面粉的糊化特性均迅速下降,但随着芽麦粉添加量的增加,下降趋势逐渐变缓;对于面粉的粉质特性,形成时间、稳定时间和粉质指数等参数均呈下降趋势,但面粉的吸水率在芽麦粉添加量超过20%时才会有明显的下降;芽麦粉添加量的增加会降低面团的拉伸特性,但是醒发时间的延长会减缓这种变化,在添加量为5%时,拉伸能量和最大阻力等参数还会略有增加。总体来说,当添加5%芽麦粉时,糊化特性会大幅度降低,面团的稳定时间在中筋粉范围内,延长面团醒发时间可以增加面团的筋力、可塑性和弹性。     

挤压处理对马铃薯全粉加工特性及微观结构的影响

采用挤压法对马铃薯全粉进行挤压处理,考察挤压温度、物料水分质量分数对马铃薯全粉加工特性及马铃 薯全粉面团弹性的影响,通过单因素试验确定最佳挤压工艺参数,采用扫描电子显微镜、差示扫描量热仪、快速黏 度测定仪、X射线衍射仪等仪器,对挤压处理前后马铃薯全粉的微观结构、热力学性质、糊化特性及结晶度变化等 进行对比分析。结果表明：当挤压温度为150 ℃、物料水分质量分数为35%时,马铃薯全粉的加工特性综合比较最 优,溶解度较高,持水性最好,冻融稳定性较好,此时马铃薯全粉面团弹性最好;挤压处理后的马铃薯全粉表面微 观结构出现褶皱,比表面积增加;热稳定性减弱,凝胶性减弱,不易回生;挤压处理使马铃薯全粉的结晶度下降。     

不同粒度区间小麦粉对半干面品质的影响

研究了四个不同粒度区间小麦粉对半干面品质的影响。结果表明,不同粒度区间的小麦粉之间的品质表现差异性显著(p<0.05),180~200目粒度区间小麦粉的粗蛋白含量、湿面筋含量和面筋指数均高于其他粒度区间小麦粉;破损淀粉和灰分含量随粒度减小逐渐增加;140~160目区间小麦粉的粉质质量指数最大,稳定时间最长,弱化值最小;140~200目区间小麦粉的吸水率差异并不显著。随小麦粉粒度减小,半干面的白度、吸水率、蒸煮损失率逐渐增加;140~160目区间小麦粉制作的半干面,其硬度最大,咀嚼性最好;160~180目区间小麦粉制作的半干面,其拉伸性能最好;180~200目区间小麦粉制作的半干面,其深层结合水比例最高,回复性、弹性、黏聚性表现最好,感官评分最高,适合制作半干面。     

Changes in ochratoxin A and type B trichothecenes contained in wheat flour during dough fermentation and bread-baking

Ochratoxin A (OTA) and type B trichothecenes are mycotoxins that occur frequently in cereals and thus can be found in cereal by-products such as bread. The aim of this work was to study the variation of the levels of OTA, deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON) and nivalenol (NIV) during the bread-making process. This was done by using wheat flour spiked with different levels of toxins. Mycotoxin levels were controlled after fermentation of the dough with yeasts (Saccharomyces cerevisiae) and after further baking at different temperature–time combinations. Analysis of variance (ANOVA) of the results showed a significant reduction in OTA level (p < 0.05) during fermentation of the dough. The reduction ranged between 29.8% and 33.5%, depending on the initial concentration of toxin in the flour. During this period, the level of the other mycotoxins studied was not modified. By contrast, in the baking phase there were significant changes in the levels of the four mycotoxins, although the reduction was similar under all the baking conditions. Considering all the temperature–time conditions tested, it can be concluded that during the baking period the average reduction of OTA, NIV, 3-ADON, and DON was 32.9%, 76.9%, 65.6%, and 47.9%, respectively.     

Wheat-Legume Composite Flour Quality

Wheat-legume composite flours were produced by blending Canada Western Extra Strong (CWES) and Canada Western Red Spring (CWRS) wheat with varying amounts of three legume proteins. Legume protein addition produced breads with lower specific loaf volume, coarser crumb and firmer texture, and cooked white-salted noodles with greater compression stress and less cutting stress than the wheat controls. The CWES wheat compensated for the negative baking effects of the legume proteins as much as the CWRS wheat. End-use quality did not change at 2% soybean protein addition. Yellow pea protein produced the greatest quality changes, followed by chickpea and soybean protein.