HMW-GSs 1Dx3+1Dy12 contribute to a suitable wheat gluten strength that confers superior Chinese steamed bread quality

The aim of this study was to clarify the effects of the high-molecular-weight glutenin subunits (HMW-GSs) 1Dx3+1Dy12 (3+12) and 1Dx4+1Dy12 (4+12) at the Glu-D1 locus on gluten and Chinese steamed bread (CSB) quality. The grain protein content and composition, gluten content and gluten index, farinograph properties, and CSB quality were investigated using four wheat near-isogenic lines (NILs) carrying HMW-GSs 1Dx2+1Dy12 (2+12), 3+12, 4+12 and 1Dx5+1Dy10 (5+10), respectively. The unextractable polymeric protein (UPP) and glutenin macropolymer (GMP) content, gluten index, dough development time, stability time, and farinograph quality number of four NILs all ranked as 5+10 > 3+12 > 2+12/4+12, such as the gluten index ranked as 5+10(44.88%) > 3+12(40.07%) > 2+12(37.46%)/4+12(35.85%); however, their contributions to the quality of CSB were ranked as 3+12 > 5+10 > 2+12/4+12, such as the specific volume ranked as 3+12(2.64 mL/g) > 5+10(2.49 mL/g) > 2+12(2.36 mL/g)/4+12(2.35 mL/g), which indicated that a suitable gluten strength (3+12) was crucial to making high-quality CSB. In addition, subunits 4+12 had a similar quality performance to low-quality subunits 2+12. All these findings suggested that, except for the acknowledged high-quality subunits 5+10, the introduction of 3+12 at the Glu-D1 locus is an efficient way for quality improvement of gluten as well as CSB.     

Investigation on prevalence of Listeria spp. and Listeria monocytogenes in animal-derived foods by multiplex PCR assay targeting novel genes

Chilled and frozen animal-derived food can be contaminated by Listeria spp., emerging foodborne pathogens in food industry. The objective of this study was to mine novel target genes by comparative genomics approach for multiplex PCR detection and differentiation of Listeria monocytogenes and other Listeria spp. in food. Multiplex PCR assay targeting the genetic markers LMOf2365_2721, AX25_00730, lin1814, int, lwe1673, and Oxidoreductase gene, resulted in the amplification of DNA fragments of 583 bp, 703 bp, 421 bp, 994 bp, 345 bp, and 201 bp from L. monocytogenes, Listeria ivanovii, Listeria innocua, Listeria seeligeri, Listeria welshimeri, and Listeria grayi, respectively. The detection limits of the multiplex assays were as low as 89 fg/μL genomic DNA and 910 CFU/mL of bacterial culture. The prevalence of Listeria spp. was determined using the developed multiplex PCR assay and standard microbiological method in a total of 200 food samples collected from different supermarkets and traditional agri-product markets in Nanjing, China. A total of 28 samples were found to be positive for the presence of Listeria, including 10.9% (6/55) of livestock meat samples, 22% (11/50) of poultry samples, 15% (6/40) of shellfish samples, 13.3% (4/30) of octopus samples and 4% (1/25) of freshwater fish samples. Of these, 13 isolates were classified as L. monocytogenes, 11 were classified as L. innocua, 2 were classified as L. ivanovii and 3 were classified as L. welshimeri. These results demonstrate that the multiplex PCR assay based on novel target genes is able to rapidly detect the Listeria spp. in 12 h with high accuracy and sensitivity, which may be used in the future for detection of Listeria spp. in animal-derived food products.     

甘薯加工中的褐变因素及其控制措施

本文在阐明甘薯营养成分与药用价值的基础上,分析了甘薯加工中的褐变因素。包括:美拉德(Maillard)反应、非焦糖化(Cara melization)反应、抗坏血酸氧化、酚类物质自动氧化等。针对褐变因素,提出了控制褐变的措施,主要有:加热处理、降低pH值、加入化学物质和还原型物质等。     

闪蒸品丽珠干红葡萄酒香气成分的GC/MS分析

采用溶剂萃取法提取闪蒸和传统品丽珠干红葡萄酒中的香气成分,经气相色谱-质谱联机分析,闪蒸干红酒鉴定出30种香气成分,包括16种酯、6种醇、3种萜烯类、4种酸和1种酮,传统干红酒鉴定出26种香气成分,包括14种酯、4种醇、4种萜烯类、2种酮、1种酸和1种醚.与传统品丽珠干红酒相比,闪蒸品丽珠干红酒酯类化合物相对含量提高29.43%,醇类化合物相对含量降低20.99%,葡萄酒香气更加浓郁、复杂、深沉.     

超临界CO_2处理腐生酵母菌细胞内外pH值的变化

超临界CO2作为一种新型的非热杀菌技术受到普遍关注,但其杀菌机理尚未揭示清楚。文中研究了腐生酵母菌经超临界CO2杀菌处理后,细胞内外pH值的变化,并探讨了细胞内外pH值的变化与菌体死亡的关系。结果表明:经过10 MPa、37℃的超临界CO2处理,细胞外的pH值逐渐降低,细胞内pH值呈现先下降,后上升,又略微下降的趋势。在超临界CO2处理过程中,细胞外pH值的降低并不是导致细胞死亡的直接因素,但可以间接提高杀菌效果;胞内pH值的变化,扰乱了细胞的正常代谢功能,是导致细胞死亡的重要因素。     

曙光油桃和丹墨油桃中多酚氧化酶性质及抑制研究

采用分光光度法研究了曙光油桃和丹墨油桃中多酚氧化酶(PPO)的酶学特性。结果表明:以邻苯二酚为底物时它们的最适温度分别为20℃和25℃,最适pH6.0和pH7.0。在80℃条件下,保持5min,两种油桃的多酚氧化酶失活比较严重。四种物质对该酶均表现出抑制作用,抑制效果由强到弱依次是抗坏血酸、柠檬酸、NaCl溶液、EDTA溶液。     

食品中多溴联苯醚及其羟基衍生物的研究进展

近年来,由于多溴联苯醚及其羟基衍生物具有毒性和污染持久性,它们的研究越来越受到重视。本文以食品中多溴联苯醚及其羟基衍生物为重点,对多溴联苯醚及其羟基衍生物的性质、主要来源、毒性、以及在食品中的污染水平和分析方法等进行了评述,为我国开展食品领域内多溴联苯醚及其羟基衍生物的限量制定和研究提供参考。     

爬山虎果籽油浸提工艺及其脂肪酸组成分析

主要研究了爬山虎果籽油的浸提工艺、理化性质和脂肪酸组成.筛选出正己烷作为爬山虎果籽油的浸提溶剂,通过正交试验确定爬山虎果籽油的最佳浸提工艺条件为:颗粒大小40目,料液比1∶9,浸提温度65℃,浸提时间80min,浸提次数2次.气相色谱法测得爬山虎果籽油的不饱和脂肪酸含量为88.63％,其中亚油酸含量为74.67％.     

Opportunities for improving plantation productivity. How much? How quickly? How realistic?

Biomass production may be increased through greater utilization of existing resources, planting more area, and by implementing intensive silvicultural practices. This paper reviews the potential of intensive silviculture to increase productivity of short and longer rotation hardwood and conifer plantations. Some silvicultural treatments produced long-term growth and site improvements: species and provenance choice, tree breeding, improving rooting volume, applying high rates of fertilizers, and irrigation, all showed this potential. Short-term gains resulted from changes to stocking rates, rotation length, planting practices, tillage, weed control, and applying starter doses of fertilizer or nitrogenous fertilizer to pole stands.The largest gains came from site selection, species and provenance choice, draining wet sites and correcting nutrient deficiencies, followed by tree breeding and irrigation. Choice of stocking level and rotation length, planting practices, weed control, and fertilizing pole stands gave potentially large benefits (>25% gains) for short-rotation crops (<12–15 years). They produced lower benefits for longer rotation plantations. Starter fertilizers, tillage and utilizing thinnings had relatively low gains. Disease and insect control were difficult to assess.Managers should consider their current management level and practices, costs and benefits, social and environmental factors, practicality, and the time required for the benefits to be achieved. Further, growth improvements measured in research studies typically are not achieved in the field, with 15–25% reductions being commonly experienced. Quality control could reduce these losses.     

Pt–free counter electrodes based on modified screen–printed PEDOT:PSS catalytic layers for dye–sensitized solar cells

One of the most highlighted advantages of dye-sensitized solar cells (DSSCs) consists in the possibility to apply simple and low-cost printing techniques and solution processable materials for their assembling. Here, we report on screen-printed Pt–free counter electrodes (CEs) based on poly(3,4–ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) dispersions with different content of rheological agent – hydroxyethyl cellulose (HEC). These PEDOT:PSS dispersions, having measured pseudoplastic and thixotropic rheological behaviour, were screen–printed onto FTO glasses. The content of rheological agent in PEDOT:PSS catalytic layers showed an effect on measured thickness, electrochemical properties, specific conductivity and subsequently on the evaluated photovoltaic performance of DSSCs. The PEDOT:PSS CE with the 0.03 wt% of HEC achieved the best electrochemical performance and specific conductivity (80 S cm⁻¹), the lowest thickness of 200 nm and transparency in VIS light spectrum over 60%. DSSCs based on this PEDOT:PSS CE reached the highest conversion efficiency of 4.2% which is only approximately 40% lower value than η=6.9% evaluated for Pt CE.