Bread-making performances of durum wheat semolina,as affected by ageing

The present study addresses the influence of ageing on the bread-making performances of durum wheat semolina by bread image analysis. Bread loaves were produced from semolina samples stored in 4 different packaging materials for up to 150 days. Sampling and bread-making trials were performed every 15 days. Results showed that ageing does affect durum wheat semolina bread-making performances, highlighting that storage time, rather than the type of packaging material, is the main factor determining quality changes in the final bread samples. In particular, a change in the crust colour parameters and a reduction of the bread slice area and height by 20–35% were observed with increasing semolina storage time, along with a slight increase of crust % area. The change in farinographic parameters of dough suggests that the observed reduction of technological quality might be due to increased stiffness and reduced extensibility of gluten occurring in aged semolina. Unlike common wheat flours, which usually improve their technological features during ageing, durum wheat semolina is negatively affected in its quality by storage. The study highlights the importance of considering bread-making performances among the quality parameters to be taken into account for the shelf life evaluation of durum wheat semolina.     

Shelf life extension of sliced wheat bread using either an ethanol emitter or an ethanol emitter combined with an oxygen absorber as alternatives to chemical preservatives

In the present study, the effect of active packaging [ethanol emitter (EE) or ethanol emitter combined with an oxygen absorber (EE + OA)] on shelf life extension of sliced wheat bread stored at 20 °C was investigated. Bread containing commercial preservatives (WP) and no preservatives (WOP) were taken as controls. Microbiological, physicochemical and sensory changes occurring in the product as a function of treatment and storage time were monitored for 30 days. Counts for yeasts and molds were 5.1, 3.8, 2.0 and 2.0 log cfu/g and for Bacillus cereus 4.7, 2.5, 2.3 and 2.0 log cfu/g for WOP, WP, EE and EE + OA treatments respectively after 30 days of storage. Initial pH 6.3 and 6.4, for WP and WOP samples remained fairly constant irrespective of specific treatment. Aroma quality deterioration during storage was due to the loss of volatile compounds and the formation of “off-flavors” through lipid oxidation. Neither the EE nor the EE + OA had an adverse effect on initial odor, taste and texture of bread. Based on sensory (texture) and microbiological data, shelf life was ca. 4 days for samples WOP; 6 days for samples WP; 24 days for samples containing the EE and at least 30 days for samples containing the EE + OA.     

火锅蘸酱常温贮存过程中微生物的变化研究

为预测和制定火锅蘸酱在常温贮存条件下的货架期,研究常温下火锅蘸酱中微生物生长趋势的变化,利用DPS软件,建立Gompertz模型,然后用生产日期相近的2个组蘸酱的微生物变化验证所建立的生长模型的准确度。研究结果表明,试验中所建立的Gompertz模型能有效地拟合火锅蘸酱在常温下菌落总数的动态变化,准确度较高,能准确预测不同贮藏时间内火锅蘸酱的菌落总数,为快速、可靠地实时预测火锅蘸酱的货架期和微生物学品质,提供了一个方便有效的方法;利用该模型可以预测火锅蘸酱12个月的保质期内菌落总数小于105cfu/g。     

3种植物提取液对蒜薹货架期品质的影响

为了研究一种新型安全的蒜薹防腐保鲜方法,控制蒜薹的采后病害,延长蒜薹的货架期并保持其品质。以苍山大田薹为试材,用1.5%百里酚、1.5%柠檬醛、0.4%香叶醇3种植物提取液浸蘸蒜薹薹梢,25℃下放置,定期测定指标。结果表明,1.5%百里酚,1.5%柠檬醛,0.4%香叶醇浸蘸处理均能够有效地抑制蒜薹薹梢霉变和薹条老化,减缓其水分、可溶性固形物、维生素C、总叶绿素的损失,进而保持了较好色泽,减少了营养成分的损失。其中,1.5%柠檬醛浸蘸处理的效果最好,1.5%百里酚、0.4%香叶醇处理效果次之。研究表明,百里酚、柠檬醛、香叶醇3种植物提取液均能保持蒜薹的品质,延长其货架期。     

棚龄对大棚土壤重金属及盐分含量的影响

阐明大棚棚龄对大棚土壤中重金属及盐分含量的影响,并为解决由此而产生的大棚蔬菜和水果的产量下降、品质变劣的问题及解决农业生产中的实践问题提供理论支持。综述了调查的不同地区和不同棚龄蔬菜大棚土壤中的重金属和盐分含量。研究发现部分大棚土壤中存在重金属污染超标现象,且随着棚龄的增加重金属含量不断上升,同时大棚土壤盐渍化趋势随栽培年限的延长愈加明显,且主要是Cl-、NO3-含量的增加。总之,大棚土壤中重金属含量升高和土壤盐渍化的原因,主要是施肥（复合肥）过量和施肥不当引起。     

6种不同柑橘蜡在默科特(Murcott)橘上应用的性能评价

经“Decco Fruitshine 402F”、“Water Wax”、“Zivdar Wax”、“FMC 890”、“FMC8201”、“FMC810”、塑料袋单果包装及清洗为对照处理的默科特果实,于常温贮藏35 d.研究结果表明,采后打蜡可以明显减少果实失重,改善果实外观,但影响果实风味.果实的异味与果实内部成分变化特别是乙醇含量的增加密切相关.     

草莓贮藏保鲜技术的研究进展

草莓皮薄、水分含量大,是一种货架期短、极易腐烂的水果。阐述了近几年来国内外采用物理、化学及生物等保鲜技术在草莓贮藏保鲜过程中的应用研究进展,为延长草莓货架期、增加草莓种植户的经济效益及草莓的精深加工提供可靠的技术依据。     

鲜切草鱼鱼腩的减菌条件优化与货架期比较

以鲜切草鱼鱼腩为原料,优化减菌剂次氯酸钠的减菌条件,并对减菌后产品的货架期进行研究,以期为鲜切草鱼产品的加工提供依据.结果表明,次氯酸钠最佳减菌处理条件为浓度300mg/L、浸泡减菌5 min、料液比1 g:5ml,菌落总数、假单胞菌数减菌率分别达83％、81％;经次氯酸钠减菌处理的鲜切鱼腩结合气调包装后置于4℃贮藏,货架期可达11d,贮藏时间比对照延长5d,货架期延长83％.次氯酸钠减菌处理可明显降低草鱼鱼腩的初始微生物数量,感官接受程度良好,并能明显延长冷藏气调保鲜草鱼鱼腩的货架期.     

基于粒子群的支持向量机SVR冰情预报研究

[目的]研究基于粒子群算法优化支持向量机SVR的黄河宁蒙段封河、开河日期预报模型。[方法]采用相关分析和成因分析相结合的方法选取合适的冰情预报因子组合,并运用粒子群算优化方法确定最优参数构建预报模型,将其运用到黄河宁蒙段封开河日期预报中。[结果]该模型预报精度高、运行时间短,预报平均误差为3.51 d,平均运行时间为10.464 s,预报效果明显优于遗传算法优化的支持向量回归与反向传播式神经网络,能够较准确地对封开河日期做出预报。[结论]基于粒子群算法优化支持向量回归的方法可以用于冰情预报。     

复合天然抗氧化剂对封鳊鱼品质的影响及货架期预测

[目的]有效延长封鳊鱼的货架期。[方法]采用传统腌制的方法制作封鳊鱼,在制作过程中添加复合天然抗氧化剂,通过测定鳊鱼脂肪在储存过程中羰基值(COV)和硫代巴比妥酸(TBA)值的变化,确定其添加效果。同时,利用ASLT法对添加复合天然抗氧化剂的封鳊鱼货架期进行预测。[结果]添加复合天然抗氧化剂的封鳊鱼货架期,在4℃下延长了30 d,在10℃下延长了30 d,在25℃下延长了30~45 d。利用ASLT法预测添加复合天然抗氧化剂的封鳊鱼在储存温度22℃和湿度50%条件下的货架期为82~104 d。[结论]研究结果可为延长封鳊鱼的货架期提供新途径。