The Effect of Active Packaging on Microbial Stability and Quality of Chinese Steamed Bread

The present study was conducted to evaluate the effect of active packaging [oxygen absorber (OA) or oxygen absorber combined with ethanol emitter (OA + EE)] on microbial stability and quality of Chinese steamed bread (CSB) stored at 25 °C. Air‐packaged CSB was taken as control. Microbiological, sensory, physical, thermal and mechanical changes were monitored as a function of treatment and storage time. On day 2 of storage total plate count was reduced by 3.1, 3.7 and 4.4 cfu/g by OA, OA + EE (1% v/v) and OA + EE (3% v/v), respectively (p < 0.05). Yeasts and moulds were inhibited during the entire storage period. No detrimental effects of OA + EE (1% v/v) were observed on organoleptic parameters, whereas OA + EE (3% v/v) gave a strong objectionable flavour and taste. Active packaging significantly (p < 0.05) delayed the increase of potential of hydrogen as compared to the control. No significant effect of active packaging was found on moisture content, water activity, colour and specific volume. An increase in the melting enthalpy of amylopectin crystallite was observed in all samples during storage. The stored CSB samples packaged with OA showed higher values of hardness compared to samples packaged with OA + EE (1% v/v), indicating the potential of ethanol as plasticizer of the protein network. The results indicate the potential application of OA and OA + EE (1% v/v) as an antimicrobial packaging system for CSB preservation. Copyright © 2015 John Wiley & Sons, Ltd.     

HDPE/木粉改性复合材料的制备及其长效吸水性能研究

加入HDPE-g-MAH、CG-8831和KH-550制备HDPE/木粉改性复合材料。研究其长效吸水性,发现吸水率随时间延长先快速增加,浸水35 d后缓慢增至平衡,HDPE-g-MAH改性效果最好,其饱和吸水率仅为1.503%。利用Fick第二扩散定律拟合吸水动力学曲线,得扩散系数D的顺序:HDPE-g-MAH增容HDPE/木粉复合材料HDPE/木粉复合材料KH-550改性HDPE/木粉复合材料CG-8831改性HDPE/木粉复合材料。并证明该吸水过程符合Fick第二扩散定律,相关系数R2值达0.99以上。HDPE/木粉改性复合材料尺寸变化系数CDCWCT。     

Particle Size of Whole Meal Rye Bread does not Affect the Digestibility of Macro-Nutrients and Non-Starch Polysaccharides and the Energy Value of Dietary Fibre in Humans

The effect of particle size of whole meal rye bread on the apparent digestibility of macro-nutrients, non-starch polysaccharides (NSP) and energy, the energy value of rye NSP and on faecal weight was studied in balance experiments in seven young women. The whole meal breads were prepared from one single batch of rye milled to two different particle sizes (coarse bread: 50% of particles >2 mm, 90% >1 mm; fine bread: 86% of particles <0·5 mm, 58% <0·2 mm). Two diets containing either coarse (350 g day⁻¹) or fine (377 g day⁻¹) whole meal bread and a low fibre control diet were consumed for 3 weeks each in a 3×3 cross-over design. Relative to the low fibre control diet, digestibility of protein, NSP and energy was significantly lower for the diets containing the whole meal breads. Digestibility of fat was the same for all diets. Partial digestible energy value for each g of NSP from coarse and fine whole meal rye bread was calculated to be −3±7 and 1±5 kJ, respectively. There were no differences between coarse and fine whole meal rye bread in the effects on the parameters measured with the exception on faecal wet weight, which was higher for the coarse bread diet.     

高职教育中石化专业专业课的教学思考

高职教育中石化专业专业课承担着更多的学生技能和素质培养的任务,教学中必须重视和突出实践性原则,加强教材改革,强化专业理论知识,培养精良的“双师型”师资队伍,利用专业课对学生职业能力培养。     

高效液相色谱法测定馒头中过氧化苯甲酰

依据GB/T 22325—2008"小麦粉中过氧化苯甲酰的测定高效液相色谱法",针对馒头样品,对前处理方法和色谱分析条件进行了验证和改进,通过大量的样品和加标回收试验,建立了馒头中过氧化苯甲酰的高效液相色谱检测方法。     

外源戊聚糖酶对国产小麦面包粉品质的影响

通过流变学试验、面包烘焙试验和面包芯质构测试,探讨了戊聚糖酶对国产小麦面包粉品质的影响。试验表明,与对照组相比较,在添加适量戊聚糖酶后,面团的流变学性质、面包品质都得到明显改善。质构测试显示,戊聚糖酶可以有效地延缓面包制品的老化现象。试验条件下,添加戊聚糖酶60μg/g(酶/小麦粉)为最适添加量。     

抗性淀粉对面粉品质及面团流变学特性影响研究

探讨抗性淀粉对小麦粉流变学特性的影响。分别考察了其对高筋粉、中筋粉的粉质特性、拉伸特性和糊化粘度特性的影响,结果表明,抗性淀粉的添加在一定程度上影响了小麦粉的流变学指标和面粉品质。具体表现为面团稳定时间和粉质评价值降低,弱化度增加,延伸度与拉伸曲线面积降低。抗性淀粉的添加使高筋粉的糊化温程升高,糊化时间延长,对中筋粉的糊化温程和时间影响较小。     

馒头在蒸制和蒸烤过程中理化及微生物指标的变化

高径比、酸度、还原糖、水分、重量、乳酸菌和酵母菌是馒头加工过程中主要的理化和微生物变化指标。本文主要对蒸制与蒸烤馒头的理化指标与微生物的变化进行了研究,得出两种加工方式馒头的相同与不同之处。     

挤压对低温脱脂花生粕氮溶指数的影响

以低温脱脂花生粕为原料,采用挤压技术,在单因素实验的基础上,利用Box-Benhnken的中心组合实验设计原理,氮溶指数(NSI)为考核指标,确定了花生粕挤压改性的最佳工艺条件,建立了数学模型。结果表明,低温脱脂花生粕挤压改性的最佳工艺条件为模孔直径12mm、物料含水量11.8%、挤压温度65℃、螺杆转速300r/min。在该工艺条件下花生粕的NSI为82.20%,和挤压前相比提高15.42%。