超滤对几种果蔬汁品质的影响

探讨了２种孔径（５０ＫＤ、１５０ＫＤ）的聚丙烯腈超滤膜对４种果蔬汁（甘蓝汁、黄瓜汁、萝卜汁和锦橙汁）品质的影响。结果表明：小分子的糖、酸、矿物质及维生素Ｃ的平均透过率超过９０％,２种膜间无显著性差异;大分子的蛋白质、果胶及脂溶性维生素Ｅ的平均透过率较低,２种膜间有显著性差异。超滤后的果蔬汁基本保持了固有风味并改善了某些不良风味。     

Thermal Pasteurization Effects on Color of Red Grapefruit Juices

Changes in color due to thermal pasteurization of two cultivars of red grapefruit juice were studied. Juices were pasteurized at 91°C using a plate heat exchanger. Apparently, thermal pasteurization changed all three color parameters (CIE L*, a*, b*) in the juice, causing a slight color shift towards lighter and brighter. Thermal pasteurization especially affected CIE b* value and chroma in juice. The reflectance spectrum in the visible region (400 nm to 700 nm) clearly showed changes in spectral distribution of light reflected from juice after pasteurization. There were no changes (P>0.05) in major carotenoid pigments (β-carotene and lycopene) in the juices after pasteurization.     

Effect of Thermal Treatment on Selected Cereals and Millets Flour Doughs and Their Baking Quality

Selected cereals (rice and sorghum) and millets (finger millet and pearl millet) were steamed for 20 min at ambient pressure. The rheological properties of doughs, made from these steamed as well raw grain flours, were characterized in addition to examining their baking quality. The two-cycle compression test was employed and instrumental values were correlated with sensory attributes (color, aroma, taste, stickiness, chewiness, tearing strength, cohesiveness, and rollability) using principal component analysis (PCA). Rice doughs made from both raw as well as thermally treated flour imparted maximum hardness (96.6–99.3 N) and least cohesiveness (0.05–0.09) with highest stickiness values (105–110°) among all the dough samples at the same moisture content. Pearl millet and raw sorghum flour doughs possessed the least instrumental hardness, adhesiveness, and stickiness and were the easiest to flatten. The PCA biplot showed that sensory and instrumental cohesiveness formed a cluster on the left side on the x axis while shear force, and sensory attributes like tearing strength, chewiness, stickiness, and rollability formed another cluster on the other side of the axis. Raw rice and finger millet doughs were associated with the high extent of instrumental and sensory stickiness. Thermally treated pearl millet and sorghum doughs were the best followed by treated rice and finger millet samples to give the desirable dough characteristics, and were quite close to wheat chapathi in texture.     

糯小麦粉添加比例对馒头品质的影响

研究将糯小麦粉添加到普通非糯小麦粉中制作馒头的品质.结果表明馒头比容不受糯小麦添加比例的影响,糯小麦粉添加比例的增加会导致外观形状、色泽、结构、弹韧性、黏牙性和总分的降低,当糯小麦粉添加比例≤10%时所有评分的降低都没有达到显著水平.峰值黏度、抗延阻力(45 min)、最大抗延阻力(45 min)、延伸(45 min)和最大延伸比(45 min)的增加都能促进除比容外的馒头评分的提高.糯小麦粉比例≤25%时随着其比例的增加,在-18℃下储存3 d的馒头坚实度的逐渐降低.说明糯小麦添加到普通非糯小麦粉中不能改善馒头的品质,但将来可能广泛应用于食品的冷冻储藏.     

Prediction of Thermal Conductivity of Fruit Juices by a Thermal Resistance Model

A model for prediction of thermal conductivity of fruit juices was developed. The model was based on the concept of thermal resistances in parallel and compared with other models and experimental values. Effect of temperature and solid concentration on thermal conductivity was discussed. Extension of the model to predict thermal conductivity of fruit juices below the freezing temperature was briefly discussed. The model gave error of less than 10% from the experimental values for juices for which such values were available.     

小麦品质性状的搭配效应研究

以面包小麦品种作试验材料,研究混合粉的搭配效应,结果如下：（１）混合粉的品质性状可以分为两大类,一大类是实现“加性效应”的性状,如蛋白质含量,和面曲线的峰高和Ｚｅｌｅｎｙ沉降值等,数值高代主要由混合粉中原料和配粉比决定的;另一大类是表现“部分显性效应”的性状,如和面时间,面包体积和面包比容等,它们的数值高低主要受硬质小麦的原料和配粉比的影响。（２）混合粉的烘烤品质主要受面包小麦的面筋强度的影响。（     

Effect of Blending Ratio on Modal Fiber Cotton Blended Yarn Quality

探讨混纺比对Modal纤维棉混纺纱性能的影响.选取Modal纤维与棉为原料,分别纺制14.5 tex的纯棉精梳纱、纯Modal纱以及Modal与棉混纺比分别为20/80、30/70、40/60、50/50的混纺精梳纱,并通过对比试验,分析了混纺比对成纱强伸性能、条干、毛羽的影响.结果表明:从提高混纺纱断裂强度考虑,混纺比选择50/50比较适宜;Modal纤维的含量在40％左右时,成纱条干较好;混纺比为40/60或50/50左右时,成纱毛羽数较低.     

Improving Quality Parameters of Functional Strawberry Juices: Optimization of Prebiotic Fiber Enrichment and Geraniol Treatment

Enrichment of strawberry juices with prebiotic fiber (inulin and oligofructose) and their preservation treatment (with ultrasound and geraniol) were optimized by response surface methodology with a Box-Behnken design in order to simultaneously maximize microbiological, nutritional, and sensory quality of juices after 2 weeks of refrigerated storage. The optimal conditions were inulin/oligofructose proportion of 5:3, 0.225 μL/mL of geraniol and ultrasound time equal to 0, with a desirability value of 0.77. After that, strawberry juices were treated at optimal conditions to investigate changes on microbiological (native microflora), nutritional (including ascorbic acid content and antioxidant capacity indicators), sensory quality and safety (simulating an eventual postharvest contamination with Escherichia coli O157:H7 and Listeria innocua) during storage. Finally, a study evaluating the performance of the optimized treatment on stability of prebiotics added to strawberry juices was carried out. The optimized treatment was highly effective to reduce native microflora counts, as well as, to inhibit those inoculated pathogens in juices. Treatment at optimal conditions did not induce any negative effect neither on antioxidant capacity indicators nor on ascorbic acid content of juices. Furthermore, the optimized treatment ensured the stability of inulin and oligofructose added to juices during storage. The simultaneous optimization allowed lower concentrations of geraniol, reducing the impact on sensory quality. Therefore, the enrichment and treatment of strawberry optimized and proposed in this work could be a feasible alternative to thermal pasteurization to ensure the microbiological quality and safety in juices, as well as, to improve nutritional and sensory quality.     

糯小麦粉添加比例对中国干白面条品质的影响

研究了糯小麦粉添加比例对中国干白面条(DWCN)品质的影响.糯小麦粉以0、10%、20%、30%、40%、50%、60%、70%、80%、90%和100%的比例添加到扬麦17号(1)粉中,并且以0、20%、40%、60%和80%的比例添加到扬麦158(1)、扬麦158(2)和扬麦17号(2)中.结果表明40%的糯小麦粉添加比例制成的DWCN具有最好的品质,其中添加40%糯小麦粉的扬麦158(1)混合粉制作的DWCN评分最高,而100%糯小麦粉则最差.DWCN的评分在很大程度上不受流变学性质如粉质仪和拉伸仪参数以及小麦粉组分、而更多的是受淀粉糊化性质的影响.DWCN质量可以通过增加峰值温度、或降低峰值黏度和回生值而加以改善.中等偏差流变学性质的100%糯小麦粉不适合于制作DWCN,而以适当比例(40%)将糯小麦粉添加到非糯小麦粉中可能有助于改善DWCN品质.     

Effects of UV-C Light Processing on Some Quality Characteristics of Grape Juices

White and red grape juices (GJs) were subjected to ultraviolet C (UV-C) light as a non-thermal preservation technology using a coiled tube UV-C reactor with nine lamps. The effects of UV-C light on microbial (total aerobic count and yeast and mould count) and some chemical quality characteristics (total phenolics, antioxidant capacity, anthocyanin and polymeric colour, etc.) of white and red GJs were investigated. The results were compared with control (untreated) and heat-treated juice samples. Single-pass UV-C treatment (12.6 J/mL) of white and red GJs resulted in 3.51 and 3.59 log reductions in total aerobic count and, 2.71 and 2.89 log reductions in yeast and mould counts, respectively. The microbial loads of both GJs were completely eliminated after two passes through the reactor (25.2 J/mL). After UV-C and heat treatments, there were no significant changes in antioxidant capacity, total phenolics, titratable acidity, soluble solids and pH of white and red GJs (P?>?0.05). The losses in monomeric anthocyanins were 6.1% and 8.7% after UV-C treatment of 12.6 and 25.2 J/mL doses, respectively. However, anthocyanin level of red GJ was significantly affected by the heat treatment with an 11.8% loss (P?<?0.05). The percent polymeric colour of the red GJ with heat treatment was significantly higher compared to the colour with the UV-C treatment.     

超声处理对玉米淀粉热性质的影响

研究超声处理前后玉米淀粉热性质的变化。采用超声波对70%水分含量的玉米淀粉进行处理。结果表明超声处理提高了糊化转变温度、膨胀度和溶解度,降低了析水率、焓值以及转变温度范围。玉米淀粉经处理后粘度降低,但其粘度曲线不改变。以上数据表明超声处理优先降解无定形区,且直链淀粉比支链淀粉更容易被降解。     

Kinetic Models for Thermal Inactivation of Multiple Pectinesterases in Citrus Juices

First-order kinetic model of a two-component system was applied to investigate heat inactivation of multiple pectinesterases in citrus juices. The conventional log-linear model was applied to determine D- and z-values of thermolabile and thermostable pectinesterases in citrus juices, respectively, for use in the two-component model. A parameter for concentration of enzyme populations in the juice was included in the model. The two-component model predicted results were in better agreement with the observed heat pasteurization curves than those predicted by the log-linear kinetic model. The two-component model is especially useful for optimizing temperature-time conditions for pasteurizing citrus juices.     

Thermal Inactivation of Yeasts in Fruit Juices Supplemented with Food Preservatives and Sucrose

Thermal inactivation of five yeasts (Candida krusei, Hansenula anomala, Saccharomyces bailii, S. cerevisiae and Torulopsis magnoliae) suspended in five fruit juices (apple, apricot, grape, orange and pineapple) as affected by potassium sorbate, sodium benzoate and sucrose was investigated. Yeasts were most sensitive to heat when suspended in orange juice. Both preservatives, at a concentration as low as 100 ppm, enhanced the rate of inactivation in juices containing no added sucrose. Supplementation of juices with sucrose (30 and 50%) resulted in protection against death of yeasts. The detrimental effects of potassium sorbate and sodium benzoate were reduced in the presence of high concentrations of sucrose. While neither preservative exhibited a consistent superior lethal effect compared with the other, overall, sodium benzoate was generally more effective than was potassium sorbate.     

热加工程度对鸡肉食用品质的影响

热加工方法及程度对鸡肉的食用品质有着非常重要的影响,以鸡胸肉和鸡腿肉为例,对其进行常压煮制及高压煮制,研究热加工程度对蒸煮损失率、多汁性、嫩度、风味的影响.结果 显示:常压煮制中心温度为85℃保温30 min,鸡胸肉的蒸煮损失率为30.3％、剪切力为27.9 N、综合评分指数最高为29.4,食用品质最佳.中心温度为90...     

白酒智能勾兑和质量评价系统的研究

白酒勾兑和评价是我国酿酒行业生产中的一项重要传统工艺,传统的人工方法易导致勾兑、调味、评酒结果的不准确性。选用VB.NET、SPSS等工具,使用了聚类分析、遗传算法等人工智能的研究方法,建立了一套利用计算机技术辅助实现白酒勾兑与调味、评价的生产管理系统。系统具有总结、提高、学习的能力,对科学评价白酒的质量和推动企业技术进步具有重要意义。     

大米的复配与米饭的品质控制研究

以不同品质大米为原料,在分析大米及米饭的物化特性的基础上进行大米复配技术的研究,为充分利用低质米资源及控制米饭品质等提供参考。结果表明:根据米饭的综合品质可将大米分为香米、较低直链淀粉含量的大米、较高直链淀粉含量的大米;以一种米质较差的大米为主料米,与米质较好的辅料米按一定的比例复配,能够改善大米的综合品质;用米饭的游离氨基酸含量、可溶性糖含量与大米的水分含量、直链淀粉含量、蛋白质含量、脂肪含量的指数式模型可以较好地预测米饭的感官品质;采用预测模型,通过规划设计,可以得到预期目标的大米复配配方。     

Effect of Thermal Sterilization on the Selected Quality Attributes of Sweet and Sour Carp

In this study, a traditional Chinese dish, a ready-to-eat sweet and sour carp was developed. The effects of sterilization temperature (110, 115, 121, and 130°C) on the selected properties, including heat penetration characteristics, as well as rheological, instrumental color, texture, and sensory attributes, were investigated at the same lethality value (F₀) of 4.5 min. The results showed that the heat penetration parameters of cooking value (C-value) and the ratio of C-value to F₀ value (C-value/F₀) exhibited an inverse relationship with processing temperature. The color and rheological properties of the sauce and the texture of the fish sterilized at 130°C were better preserved compared to those sterilized at other temperatures. The sensory attributes of the product sterilized at 130°C scored highest among the final products sterilized at the four temperatures. This study suggested that short-time sterilization at a high temperature can minimize the negative thermal impact on sweet and sour carp product, which would be feasible in the practical production.     

热处理对鲜豆奶中胰蛋白酶抑制子活性的影响

分别以95℃、120℃、140℃三种温度处理鲜豆奶,研究热处理对胰蛋白酶抑制子活性的影响。测定结果表明要达到胰蛋白酶抑制子90％的失活率,95℃时需要35min;120℃时需要7min;而140℃时只需要60s左右。胰蛋白酶抑制子的热致死时间曲线表明,加热温度增加30℃,钝化胰蛋白酶抑制子90％的热处理时间可缩短10倍。     

石榴贮藏期间间歇升温处理对果实品质的影响

以陕西临潼净皮甜石榴为试材,研究了间歇升温处理对石榴果实贮藏期间品质变化的影响。结果表明:石榴在(5.0±0.5)℃条件下贮藏,每隔6 d在(15±0.5)℃下间歇升温处理24 h,能有效保持果粒可溶性固形物含量、总糖含量和可滴定酸含量,减缓果皮褐变指数升高速率,降低果实腐烂率,贮藏120 d果实外观色泽鲜艳.籽粒感官品质良好,保鲜效果理想。