Product stability and sequestration mechanisms in Solanum tuberosum engineered to biosynthesize high value ketocarotenoids

To produce commercially valuable ketocarotenoids in Solanum tuberosum, the 4, 4′ β-oxygenase (crtW) and 3, 3′ β-hydroxylase (crtZ) genes from Brevundimonas spp. have been expressed in the plant host under constitutive transcriptional control. The CRTW and CRTZ enzymes are capable of modifying endogenous plant carotenoids to form a range of hydroxylated and ketolated derivatives. The host (cv. Désirée) produced significant levels of nonendogenous carotenoid products in all tissues, but at the apparent expense of the economically critical metabolite, starch. Carotenoid levels increased in both wild-type and transgenic tubers following cold storage; however, stability during heat processing varied between compounds. Subcellular fractionation of leaf tissues revealed the presence of ketocarotenoids in thylakoid membranes, but not predominantly in the photosynthetic complexes. A dramatic increase in the carotenoid content of plastoglobuli was determined. These findings were corroborated by microscopic analysis of chloroplasts. In tuber tissues, esterified carotenoids, representing 13% of the total pigment found in wild-type extracts, were sequestered in plastoglobuli. In the transgenic tubers, this proportion increased to 45%, with esterified nonendogenous carotenoids in place of endogenous compounds. Conversely, nonesterified carotenoids in both wild-type and transgenic tuber tissues were associated with amyloplast membranes and starch granules.

Pre-anthesis ovary development determines genotypic differences in potential kernel weight in sorghum

Kernel weight is an important factor determining grain yield and nutritional quality in sorghum, yet the developmental processes underlying the genotypic differences in potential kernel weight remain unclear. The aim of this study was to determine the stage in development at which genetic effects on potential kernel weight were realized, and to investigate the developmental mechanisms by which potential kernel weight is controlled in sorghum. Kernel development was studied in two field experiments with five genotypes known to differ in kernel weight at maturity. Pre-fertilization floret and ovary development was examined and post-fertilization kernel-filling characteristics were analysed. Large kernels had a higher rate of kernel filling and contained more endosperm cells and starch granules than normal-sized kernels. Genotypic differences in kernel development appeared before stamen primordia initiation in the developing florets, with sessile spikelets of large-seeded genotypes having larger floret apical meristems than normal-seeded genotypes. At anthesis, the ovaries for large-sized kernels were larger in volume, with more cells per layer and more vascular bundles in the ovary wall. Across experiments and genotypes, there was a significant positive correlation between kernel dry weight at maturity and ovary volume at anthesis. Genotypic effects on meristem size, ovary volume, and kernel weight were all consistent with additive genetic control, suggesting that they were causally related. The pre-fertilization genetic control of kernel weight probably operated through the developing pericarp, which is derived from the ovary wall and potentially constrains kernel expansion.

Role of heat treatment in the processing and quality of oat flakes

This thesis reports on investigations into the influence of heat treatment on the manufacturing of oat flakes. Sources of variation in the oat flake quality are reviewed, including the whole chain from the farm to the consumer. The most important quality parameters of oat flakes are the absence of lipid hydrolysing enzymes, specific weight, thickness, breakage (fines), water absorption. Flavour, colour and pasting properties are also important, but were not included in the experimental part of this study. Of particular interest was the role of heat processing. The first possible heat treatment may occur already during grain drying, which in Finland generally happens at the farm. At the mill, oats are often kilned to stabilise the product by inactivating lipid hydrolysing enzymes. Almost invariably steaming is used during flaking, to soften the groats and reduce flake breakage. This thesis presents the use of a material science approach to investigating a complex system, typical of food processes. A combination of fundamental and empirical rheological measurements was used together with a laboratory scale process to simulate industrial processing. The results were verified by means of industrial trials. Industrially produced flakes at three thickness levels (nominally 0.75, 0.85 and 0.90 mm) were produced from kilned and unkilned oat groats, and the flake strength was measured at different moisture contents. Kilning was not found to significantly affect the force required to puncture a flake with a 2mm cylindrical probe, which was taken as a measure of flake strength. To further investigate how heat processing contributes to flake quality, dynamic mechanical analysis was used to characterise the effect of heat on the mechanical properties of oats. A marked stiffening of the groat, of up to about 50% increase in storage modulus, was observed during first heating at around 36 to 57°C. This was also observed in tablets prepared from ground groats and extracted oat starch. This stiffening was thus attributed to increased adhesion between starch granules. Groats were steamed in a laboratory steamer and were tempered in an oven at 80 110°C for 30 90 min. The maximum force required to compress the steamed groats to 50% strain increased from 50.7 N to 57.5 N as the tempering temperature was increased from 80 to 110°C. Tempering conditions also affected water absorption. A significantly higher moisture content was observed for kilned (18.9%) compared to unkilned (17.1%) groats, but otherwise had no effect on groat height, maximum force or final force after a 5 s relaxation time. Flakes were produced from the tempered groats using a laboratory flaking machine, using a roll gap of 0.4 mm. Apart from specific weight, flake properties were not influenced by kilning. Tempering conditions however had significant effects on the specific weight, thickness and water absorption of the flakes, as well as on the amount of fine material (<2 mm) produced during flaking. Flake strength correlated significantly with groat strength and flake thickness. Trial flaking at a commercial mill confirmed that groat temperature after tempering influenced water absorption. Variation in flake strength was observed , but at the groat temperatures required to inactivate lipase, it was rather small. Cold flaking of groats resulted in soft, floury flakes. The results presented in this thesis suggest that heating increased the adhesion between starch granules. This resulted in an increase in the stiffness and brittleness of the groat. Brittle fracture, rather than plastic flow, during flaking could result in flaws and cracks in the flake. These would be expected to increase water absorption. This was indeed observed as tempering temperature increased. Industrial trials, conducted with different groat temperatures, confirmed the main findings of the laboratory experiments. The approach used in the present study allowed the systematic study of the effect of interacting process parameters on product quality. There have been few scientific studies of oat processing, and these results can be used to understand the complex effects of process variables on flake quality. They also offer an insight into what happens as the oat groat is deformed into a flake.

Effects of CO2 enrichment on microstructure and ultrastructure of two species of freshwater green algae

order to investigate the morphological response of freshwater green algae to elevated CO2 concentration, Chlamydomonas reinhardtii Dang and Scenedesmus obliquus Kutz were cultured with enriched CO2, and their microstructure and ultrastructure were examined by microscopy and electron microscopy. The effect of CO2 enrichment to 186 mumol/L, was insignificant on the shape and size of C. reinhardtii, but significant in reducing the volume of S. obliquus. High-CO2 increased the amount of chloroplast. The pyrenoids occurred in low-CO2-grown cells but not in high-CO2-grown ones and more starch granules were observed in the former.

青藏高原栽培青稞遗传多样性研究

青稞，是我国藏区居民对裸大麦的称谓，它不仅是藏民的主要食粮、燃料和牲畜饲料，而且也是啤酒、医药和保健品生产的原料；青稞不仅为藏区人民的健康和经济发展做出了很大的贡献，而且对人类健康和社会经济的可持续发展都有重要的意义。青藏高原是我国及世界上青稞分布和种植面积最大的地区，资源极其丰富。虽然从经典遗传直到分子标记对我国大麦遗传多样性都有研究，但研究手段、数量仍然不够深入，对我国大麦资源遗传多样性研究的信息非常有限，不能很好地满足大麦遗传研究和育种应用的需要，尤其是对西藏栽培大麦的遗传多样性的研究还只是刚刚开始，关于栽培青稞多态性的研究报道很少。本研究采用SSR标记和蛋白质电泳两类技术，从SSR标记位点、单体醇溶蛋白、B组醇溶蛋白和淀粉粒结合蛋白（SGP）等四个方面对我国青藏高原栽培青稞的遗传多样性进行了综合评价。 SSR标记具有基因组分布广泛、数量丰富、多态性高、容易检测、共显性、结果稳定可靠、实验重现性好、操作简单、经济、易于高通量分析等许多优点，被认为是用于遗传多样性、品种鉴定、物种的系统发育、亲缘关系及起源等研究的非常有效的分子标记。本研究采用SSR标记分析了64份青藏高原栽培青稞的遗传多样性，同时评估SSR标记在我国大麦育种和品种鉴定中的应用潜力。选择了30个已知作图位点SSR标记，其中25个标记与重要性状的控制位点连锁紧密。选择的30个SSR标记，5个未得到很好的扩增产物，3个无多态性。22个多态性SSR标记位点中，每位点检测出等位基因2~15个，共检测出等位基因132个，平均每位点6.0 个。各多态位点检测出基因型为2~11种，位点HVM33的基因型最多。各多态位点的多态信息指数为0.16~0.91, 平均为0.65。根据PIC值选择了13个SSR标记用于我国青藏高原栽培青稞基因型鉴定，这些标记的PIC值为0.6以上。结合PIC值和基因型差异，选择了8个多态信息含量高的SSR标记，构建了高效指纹图谱，此图谱能把64份材料完全区分。 贮藏蛋白电泳分析是研究相关编码蛋白基因多态性的非常有效的方法。大麦单体蛋白与小麦醇溶蛋白相对应，具有丰富的多态性，可用于大麦遗传多样性、品种鉴定和群体进化等研究。本研究通过A-PAGE电泳技术研究了84份青藏高原栽培青稞的单体醇溶蛋白多态性。大麦单体醇溶蛋白图谱与小麦醇溶蛋白电泳图谱类似，所分离的蛋白清晰地分为ω－，γ－，β－和α－四个部分。青藏高原栽培青稞单体醇溶蛋白具有丰富的多态性，84份青稞材料中存在43条不同的蛋白带，75种组合带谱；其中67种为单一材料所独有，另8种则分别包含了2-3份材料。每份材料中拥有醇溶蛋白带为6－16条，含有6-10条单体醇溶蛋白带材料较多。西藏和四川材料群体单体醇溶蛋白多态性不同，具有区域特异性。西藏材料中发现了40条不同蛋白带，3条特异带，46 种蛋白组合；四川材料中出现了40种不同蛋白带，26种条带组合, 3条特异带。基于单体蛋白多态性的聚类与材料的来源有一定的相关性。A-PAGE单体蛋白具有丰富的多态性，可作为遗传研究和品种鉴定的标记。 大麦醇溶蛋白（hordein）是大麦籽粒的主要贮藏蛋白，与大麦的营养品质和加工品质密切相关，而且具有丰富的多态性，广泛用于品种鉴定、种质筛选、遗传多样性和亲缘关系研究。B组醇溶蛋白是主要的醇溶蛋白组份，约占总醇溶蛋白的80%，而且具有丰富的多态性。本研究采用SDS-PAGE分析了72份青藏高原栽培青稞B组醇溶蛋白的遗传多样性。青藏高原栽培青稞B组醇溶蛋白具有丰富的多态性，72份青稞材料中存在15种蛋白带，30种组合带谱，其中15种为单一材料所独有，另15种则分别包含了2-10份材料。每份材料中B组醇溶蛋白条带数为4-8条，含5、6条的材料较常见。不同来源的群体材料间B组醇溶蛋白组成存在差异，西藏青稞含有26种蛋白组合带谱，其中有19种特异带谱；四川群体中共发现11种蛋白组合带型，其中有4种特有带谱。两群体中都存在稀有条带。聚类分析将材料分成三组，材料聚类与材料来源地没有明显的相关性。 淀粉粒蛋白（Starch granule proteins, SGPs）是一类与淀粉粒结合的微量蛋白，一些淀粉粒蛋白具有淀粉生化合成中主要的酶蛋白功能，其变异会影响淀粉含量和特性，从而影响淀粉的应用。关于我国大麦淀粉粒组成研究还未见报道。本实验首次开创了我国大麦淀粉粒结合蛋白的研究工作。采用SDS-PAGE电泳技术研究了青藏高原栽培青稞的SGP组成，并分析了不同SGP组合间淀粉含量的差异，初步探索了所分离的SGP蛋白与淀粉合成的关系。66份青稞材料中分离了10种主要的SGP，其表观分子量为40-100KD，低于60KD的SGP带有7条，共有16种组合带谱；各SGP蛋白和组合带谱出现的频率存在差异，青藏高原青稞的SGP组成存在多态性。西藏青稞和四川青稞的SGP组成有很大差异，SGP组成具有地域差异性，西藏青稞含有12种蛋白组合带谱，其中有9种特异带谱；四川群体中共发现7种蛋白组合带型，其中有4种特有带谱；两群体中仅有3种共同的蛋白组合带谱。SGP蛋白特性将66份青稞分为三组, 即Ⅰ、Ⅱ、Ⅲ，材料聚类与材料来源具有一定的相关性。不同组合带谱材料间淀粉含量差异显著性检验结果显示，不同带谱间材料的总淀粉含量、直链淀粉含量和支链淀粉含量有差异，带谱2（SGP1+3+7+9+10）和8（SGP1+2+4+6+8）的总淀粉含量及支链淀粉含量显著大于组合带谱3（SGP1+3+7+10）的总淀粉含量。组合带谱7（SGP1+2+6+8）的直链淀粉含量显著低于带谱11（SGP1+5+8）的直链淀粉。带谱SGP2、3、4、5、6、7、8、9、10可能参与淀粉合成，SGP9可能与高支链淀粉的合成相关。 SSR标记位点、单体醇溶蛋白、B组醇溶蛋白、淀粉结合蛋白等四个方面的研究结果表明青藏高原SSR标记多态性、单体醇溶蛋白多态性、B组醇溶蛋白多态性和SGP多态性都非常丰富，与青藏高原是栽培青稞的多样性分布中心的观点一致。 青藏高原栽培青稞的SSR标记、单体醇溶蛋白、B组醇溶蛋白和SGP多态性表现出很大差异。SSR标记覆盖了整个基因组，多态性非常高。单体蛋白、B组醇溶蛋白、SGP蛋白是育种中非常关注的性状，他们只是代表基因组中的某一区域或位点，多态性相对较低。但单体蛋白多态性很高，84份材料中检测出43条不同蛋白带，75种不同的组合带谱。SSR标记技术和单体蛋白技术都是遗传多样性研究的有力工具，但单体蛋白技术不仅多态性高，而且经济、操作简便，是种质鉴定的理想方法。 对不同标记的多态性材料数据进行聚类，聚类图能为我们提供各材料间的遗传相似信息，为材料选择提供参考。但材料聚类与材料来源的地理区域的相关性表现不一致。SSR聚类和B组醇溶蛋白聚类与材料的来源地无相关性，而单体醇溶蛋白和SGP聚类与材料来源地有一定相关性，即西藏群体和四川群体分别有集中类群，这可能是人为选择的附加效应。 不同来源的群体材料的遗传多样性不同，具有区域特异稀有基因，加强不同地区间资源的交换和配合使用，有利于增加群体遗传多样性和新品种培育。 青藏高原栽培青稞的麦芽浸提性状、淀粉性状、病虫及裸粒等重要农艺性状控制位点存在丰富的变异，遗传基础宽广，可能蕴藏着多种不同的等位基因，是研究重要性状遗传特性、基因资源挖掘和遗传育种的宝贵资源库。 Hulless barley, due to its favorable attributes such as high feed value, good human nutrition，rich dietary fiber and ease processing, attracts people,s attention . Hulless barley plays a very important role in Tibetan life, used as essential food crop, main animal feed and important fuel. In addition to tsampa (roasted barley flour), a main food for Tibetan, hulless barley is also made into cake, soup, porridge, recent naked barley liquor and cornmeal. Qinghai-Tibet Plateau is one of a few areas which plant naked barley widely in the world and also has a long growing history. Genetic diversity of the cultivated hulless barley in this region , however, has not been documented. The study of genetic diversity existing within this population is of particular interest in germplasm identification, preservation, and new cultivar development. This study analyzed the genetic diversity of the cultivated naked barley from Qinghai-Tibet plateau through the study of SSR marker loci and monomeric prolamins, B-horden and starch granule proteins. SSRs are present abundantly in genomes of higher organisms and have become a popular marker system in plant studies. SSRs offer a number of advantages, such as the high level of polymorphisms, locus specificity, co-dominance, reproducibility, ease of use through PCRand random distribution throughout the genome. In barley, several hundred SSRs have been developed and genetically mapped and can therefore be selected from specific genomic regions. The genetic diversity of 64 cultivated naked barley from Tibet and Sichuan was studied with 30 SSRs of known map location.Among the selected SSR markers, PCR products of 5 SSR markers were not obtained and 3 SSR marker loci were monomeric. A total of 132 alleles were identified at 22 polyomeric SSR loci. The number of alleles per locus ranged from 2 to 15, with an average of 6.0. The polymorphism information content values for the SSRs ranged from 0.08 to 0.94, with an average of 0.65. 13 SSR markers with the PIC value >0.6 have been selected for discrimination of Qinghai-Tibet naked barley genotypews. A finger Print map was developed through 7 SSR markers with the high PIC value. It could be used as an efficient tool for gene discovery and identification of gernplasm. Hordeins, the main storage proteins of the barley seed, are composed of momomeric and polymeric prolamins and divided into -A, B, C and D groups in order of decreasing electrophoretic mobility. Hordeins show high inter-genotypic variation and have been extensively used as markers for cultivar identification and analyzing the genetic diversity. This study analyzed the genetic diversity of B-hordein in 72 naked barley from Qinqhai-Tibet Plateau. Extensive diversity was observed. A total of 15 different bands and 30 distinct patterns were found. Jaccard's coefficient of similarity was calculated, and the accessions were divided into three　main groups by cluster analysis using UPGMA. Differentiation among the populations from different collecting regions based on the polymorphism of B-hordein was investigated. Monomeric prolamins show high inter-genotypic variation and have been used as molecular markers for cultivar identification, analyzing the genetic diversity in collections and investigating the evolution processes and structure of populations However, the cultivated hulless accessions from Qinghai-Tibet Pateau in China have never been examined with respect to monomeric prolamins. This study analyzed the genetic diversity of monomeric prolamins (protein fraction corresponding to wheat gliadins) using the Acid -PAGE technique in eighty-four cultivated hulless barley from Qinqhai-Tibet Plateau in China. Extensive diversity was observed. A total of 43 different bands were found, of which 21 different bands were in the region of ω group, 8 in the region of γ, 8 in the region of β, and 6 in the region of α group. Among the 86 accessions, 75 distinct patterns were identified. The number of bands ranged from 6 to 16, depending on the variety. Jaccard’s coefficient of similarity was calculated, and the lines were grouped by cluster analysis using UPGMA. A dendrogram was obtained from the analysis of the groups and five main clusters were identified. No relationship between the distribution in the dendrogram and growth habits and origins of the cultivars could be detected. Starch is the major constituent of the cereal endosperm, comprising approximately 65% of the dry weight of the mature wheat grain. The starch formed in all organs of plants is packaged into starch granules, which vary widely between species and cultivars in size and shape. Wheat endosperm starch granules contain about corresponding to the main biosynthase of starch. This report firstly dealed with intraspecific variation of the major SGPs in cultivated naked barley from Qinghai-Tibet plateau. A total of 10 major SGPs were observed in the range of 40KD-100KD and 16 types of patterns were found. Based on the variation of SGPs, accessions studied were classified into 3 groups. A geographical cline of electrophoregram was observed. In addition, significance test of the difference of starch content among groups and types of patterns were done, and the results indicated those SGPs could be related to the content of starch. Diagram obtained through cluster analysis exhibited a structuration of diversity and genetic relationship among cultivated hulless accessions. In breeding program, parents with genetically distant relationship for hybridization will increase genetic diversity of progenies. In conclusion, cultivated naked barley from Qinghai-Tibet Plateau in China presents a high variability with respect to monomeric prolamins，SSR markers , B- hordeins and SGPs. The result of this study supports Qinghai-Tibet Plateau is the center of cultivated hulless barley and the cultivated naked barley is considered to be a gene pool with large diversity and could be applied to breeding for cereal.

青藏高原青稞淀粉资源的评价

青稞（Hordeum vulgare L.var．nudum Hook．f.），即裸大麦，是兼食用、饲用和酿造于一体的作物，有着重要的利用价值。淀粉是青稞籽粒中含量最多、最重要的碳水化合物，淀粉含量、直支淀粉比将会直接影响淀粉的功能特性，进而影响淀粉的应用领域。我国青藏高原青稞的栽培和食用历史悠久，特色青稞资源极其丰富。目前关于青藏高原青稞淀粉特性的报道还不多见，筛选和培育特色淀粉青稞利于拓展青稞的应用领域, 从而提高其经济价值。 本研究以114份青藏高原青稞品种(系)为实验材料，通过SDS-PAGE对材料的胚乳淀粉颗粒结合蛋白（SGAPs）进行分离，确定各蛋白的分子量大小、组合类型和多态性等。然后按照国标法测试材料的籽粒总淀粉含量和直链淀粉含量，通过微型糊化粘度仪分析相应的淀粉糊化特性，最后使用显微镜观察比较了青稞的淀粉颗粒形态特征。主要结果如下： 1、114种青稞中共分离出20种不同的SGAP条带，条带分子量为35.00～112.39 KDa，分布频率为12.28～97.37%。材料含有的SGAPs条带数从10到14不等，超过一半的材料含11种SGAP条带。20种条带形成16种组合类型，其中西藏地区青稞包含所有16个组合类型，四川地区青稞包含其中12个组合类型。青藏高原青稞籽粒淀粉颗粒结合蛋白的差异很大，遗传多样性丰富。 2、114份青稞的总淀粉含量、直链淀粉含量、直支淀粉比、峰值粘度、糊化温度和峰值温度的变幅分别为51.26～66.70%、14.64～29.74%、0.17～0.42、194～1135BU、58.8～65.2℃和81.4～92.4℃，相应的平均值分别为59.82%、23.60%、0.31、722.30BU、62.1℃和88.8℃。群体在总淀粉含量、直链淀粉含量、直支淀粉比、峰值粘度、糊化温度和峰值温度上的分布具有明显的正态性；所有胚乳淀粉体的淀粉粒都呈复粒结构。对西藏和四川的材料进行了分组比较， 两地区的青稞在直链淀粉含量和直支淀粉比上的差异达到显著水平。 3、筛选出18份具有特殊淀粉特性的青稞品种，其中5份材料的总淀粉含量超过65%，包括NB63-1、NB67、甘孜白六棱、98221-1和NB63；3份材料的直链淀粉含量大于29%，包括藏青85、藏青3号和喜马拉6号；8份材料的直支淀粉比小于0.25，包括99033-6、春青稞、阿坝330、Jan-03、米麦114、396、NB63-1和92013；7份材料的糊化温度低于60℃，同时材料的峰值粘度大于1000BU,并且峰值温度低于90℃，包括足捉春、Jan-03、阿坝330、米麦114、春青稞、20003和阿青5号。 4、各淀粉特性间存在高度相关性。直链淀粉含量和直支淀粉比与糊化温度成极显著正相关，与峰值粘度成极显著负相关，与A型淀粉粒数量和大小呈负相关。不同SGAPs组合的品种之间，淀粉含量和淀粉糊化特性间差异均达显著水平。SGAP2、SGAP5、SGAP6和SGAP7可能对籽粒直链淀粉含量、直支淀粉比和糊化温度有正向效应；SGAP3、SGAP9∼SGAP20可能对峰值粘度有正向效应。 本研究对青藏高原青稞淀粉资源进行了较为全面的评价，对该区青稞淀粉特性有了系统的认识。研究筛选出的特殊青稞品种可作为青稞育种和青稞淀粉工业应用的潜在资源，淀粉特性差异巨大的众多青稞品种也为拓宽青稞应用领域提供了丰富的资源保障。本研究对部分SGAPs在性质上的鉴定和功能上的初步推断为青稞材料的筛选提供了指导，也为品质育种提供了理论参考。 Hulless barley (naked barley, Hordeum vulgare L.) is a short- season, early maturing crop with a wide range of adaptation. It has been attracting more and more attention due to its superior nutrition and extensive industrial applications. Starch is the main ingredient in hulless barley seeds which makes up 65 percent of hulless barley’s dry weight. The ratio of the amylose/amylopectin and the size, shape, distribution of starch granules can affect the physico-chemical and functional properties of starch, which may turn affect its utilizations. The Qinghai-Tibet Plateau, which is located in southwestern China, is a typical area of vertical agricultural ecosystem and one of the barley origin centers with abundant hulless barley resources. There are little reports about hulless barley in Qinghai-Tibet Plateau at present. To screen and cultivate some characteristic hulless barley can improve its value. An improved SDS-PAGE was used to identify SGAPs combination of 114 hulless barley varieties. Starch content (total starch and amylose starch) was determined according to the standard methods GB5006-85 and GB/T 15683 using PerkinElmer M341 Precision Automatic Polarimeter and UV spectrophotometer 755B respectively. The pasting properties were measured by BRABENDER Micrio Visco-Amylo- Graph 803201. The morphology of starch granules were observed and compared with Axioplan 2 Imaging light microscopy. The following were the results obtained: 1. There were 20 major SGAPs presented in 114 varieties, with the molecular weight ranged from 35.00 to 112.39 KDa, and the frequencies ranged from 12.28% to 97.37%. The number of SGAP bands in each accession varied from 10 to 14, more than half of the population had 11 bands. There were 16 distinct SGAP patterns in the 114 varieties, the Tibet hulless barley had all of the 16 types and the Sichuan hulless barley had 12 types. The results indicated the Qinghai-Tibet Plateau hulless barley had a polymorphism of the SGAPs. 2. The ranges of the total starch content, amylose content, Am/Ap, peak viscosity, pasting temperature and peak temperature of the 114 hulless barley were 51.26～66.70%,14.64～29.74%,0.17～0.42,194～1135BU,58.8～65.2 and 81.4℃～92.4, with an average of ℃59.82%, 23.60%, 0.31, 722.30BU, 62.1 and 88.8,℃℃ respectively. The distributions of the total starch content, amylose content, Am/Ap, peak viscosity, pasting temperature and peak temperature were visibly normal school. All of the amyloplasts in endosperm of varieties showed bimodal size distributions.The main starch properties of hulless barley from Tibet and Sichuan were separated and compared, the differences on amylose content and Am/Ap were obvious. 3. Eighteen accessions which had special starch properties were screened out. Five accessions with total starch content beyond 65%, including NB63-1, NB67, Ganzibailiuleng, 98221-1 and NB63; three accessions, Zangqing85, Zangqing3 and Ximala6, with the highest amylose content (>29%); five accessions with Am/Ap less than 0.25, including 99033-6, Chun Qingke, A Ba 330, Jan-03, Mi Mai114, 396, NB63-1 and 92013; seven accessions had a pasting temperature under 60, ℃meanwhile their peak viscosity beyond 1000BU and their peak temperature under 90℃，including Zu Cuochun, Jan-03, A Ba 330, Mi Mai 114, Chun Qingke, 20003 and A Qing 5. 4. There were high correlations between starch properties. Amylose content and Am/Ap were positively correlated to pasting temperature, negatively correlated to peak viscosity, negatively correlated to the number and granule size of A-type granule. Different SGAP combinations caused significant diversities in starch content and pasting properties. SGAP2, SGAP5, SGAP6 and SGAP7 may have positive effect on amylose content, Am/Ap and pasting temperature; SGAP3, SGAP9∼SGAP20 may have positive effect on peak viscosity. Our research made a comprehensive evaluation on the hulless barley starch from the Qinghai-Tibet Plateau, we can get a systemic understanding. Some special accessions were screened out can be used on the hulless barley breeding lines and industries utilization.The combination of the SGAPs may become a criterion to evaluate the hulless barley endosperm starch quality. Consequently, the results will be good information for further studies on the hulless barley.

Development of food ingredients for modulation of glycemia

Starches are a source of digestible carbohydrate and are frequently used in formulated food products in the presence of other carbohydrates, proteins and fat. This thesis explored the effect of addition of neutral (Konjac glucomannan) or charged (milk proteins) polymers on the physical characteristics and digestion kinetics of waxy maize starch. The aim was to identify mechanisms to modulate the pasting properties and subsequent susceptibility to amylolytic digestion. Addition of αs- or β-caseinate protein fractions to waxy maize starch restricted granular swelling during gelatinisation, increasing granule integrity. It was shown that, while β-caseinate can adsorb to starch granules during pasting, αscaseinate can be absorbed into maize starch granules. The resultant effect was a reduction in granule size after heating, more intact granules and a subsequent decrease in starch digestion in vitro as determined by analysis of reducing sugars. The ability of αs-caseinate to reduce the level of amylolytic digestion was confirmed through in vivo pig (Teagasc, Moorepark) and human (University of Surrey, UK) trials. The scope of the thesis extended to the development of a new automated cell for attachment to a rheometer to measure digestion kinetics of starch-protein mixtures. In conclusion, the thesis offers new approaches to modulation of the physical characteristics of unmodified starch during gelatinisation and suggests that the type of protein and/or polysaccharide used in starch-based food systems may influence the ability of the food to modulate glycemia. This is an important consideration in the design of foods with positive health benefits.

Optimisation of time/temperature treatment, for heat treated soft wheat flour

Chlorination of wheat flour in the EU countries has been replaced in recent years, to some extent, by heat treated flour which is used to produce high ratio cakes. Heat treated flour allows high ratio recipes to be developed which generate products with longer shelf life, finer texture, moist crumb and sweeter taste. The mechanism by which heat treatment improves the flour is not fully understood, but it is known that during the heat treatment process, protein denaturation and partial gelatinisation of the starch granules occurs, as well as an increase in batter viscosity. Therefore, it is important to optimize the flour heat treatment process, in order to enhance baking quality. Laboratory preparation of heat treated base wheat flour (culinary, soft, low protein) was carried out in a fluidised bed drier using a range of temperatures and times. The gluten was extracted from the final product and its quality was tested, to obtain objective and comparative information on the extent of protein denaturation. The results indicated that heat treatment of flour decreases gluten extensibility and partial gelatinisation of the starch granules occurred. After heat treatment the gluten appeared to retain moisture. The optimum time/temperature for the heat treatment of base flour was 120-130°C for 30 min with moisture content of ˜12.5%.© 2012 Elsevier Ltd. All rights reserved.

Investigation of the fracture mode for hard and soft wheat endosperm using the loading-unloading bending test

Investigation of the fracture mode for hard and soft wheat endosperm was aimed at gaining a better understanding of the fragmentation process. Fracture mechanical characterization was based on the three-point bending test which enables stable crack propagation to take place in small rectangular pieces of wheat endosperm. The crack length can be measured in situ by using an optical microscope with light illumination from the side of the specimen or from the back of the specimen. Two new techniques were developed and used to estimate the fracture toughness of wheat endosperm, a geometric approach and a compliance method. The geometric approach gave average fracture toughness values of 53.10 and 27.0 J m(-2) for hard and soft endosperm, respectively. Fracture toughness estimated using the compliance method gave values of 49.9 and 29.7 J m(-2) for hard and soft endosperm, respectively. Compressive properties of the endosperm in three mutually perpendicular axes revealed that the hard and soft endosperms are isotropic composites. Scanning electron microscopy (SEM) observation of the fracture surfaces and the energy-time curves of loading-unloading cycles revealed that there was a plastic flow during crack propagation for both the hard and soft endosperms, and confirmed that the fracture mode is significantly related to the adhesion level between starch granules and the protein matrix.

Surface properties and locations of gluten proteins and lipids revealed using confocal scanning laser microscopy in bread dough

Surface properties of gluten proteins were measured in a dilation test and in compression and expansion tests. The results showed that monomeric gliadin was highly surface active, but polymer glutenin had almost no surface activity. The locations of those proteins in bread dough were investigated using confocal scanning laser microscopy and compared with polar and nonpolar lipids. Added gluten proteins participated in the formation of the film or the matrix, surrounding and separating individual gas cells in bread dough. Gliadin was found in the bulk of dough and gas 'cell walls'. Glutenin was found only in the bulk dough. Polar lipids were present in the protein matrix and in gas 'cell walls', as well as at the surface of some particles, which appeared to be starch granules. However, nonpolar lipid mainly occur-red on the surface of particles, which may be starch granules and small lipid droplets. It is suggested that the locations of gluten proteins in bread dough depends on their surface properties. Polar lipid participates the formation of gluten protein matrix and gas 'cell walls'. Nonpolar lipids may have an effect on the rheological properties by associating with starch granule surfaces and may form lipid droplets. (C) 2004 Published by Elsevier Ltd.

Optimization of a sponge cake formulation with inulin as fat replacer: structure, physicochemical, and sensory properties

The effects of several fat replacement levels (0%, 35%, 50%, 70%, and 100%) by inulin in sponge cake microstructure and physicochemical properties were studied. Oil substitution for inulin decreased significantly (P < 0.05) batter viscosity, giving heterogeneous bubbles size distributions as it was observed by light microscopy. Using confocal laser scanning microscopy the fat was observed to be located at the bubbles’ interface, enabling an optimum crumb cake structure development during baking. Cryo-SEM micrographs of cake crumbs showed a continuous matrix with embedded starch granules and coated with oil; when fat replacement levels increased, starch granules appeared as detached structures. Cakes with fat replacement up to 70% had a high crumb air cell values; they were softer and rated as acceptable by an untrained sensory panel (n = 51). So, the reformulation of a standard sponge cake recipe to obtain a new product with additional health benefits and accepted by consumers is achieved.

Effect of fat replacement by inulin on textural and structural properties of short dough biscuits

The aim of this study was to evaluate the effects of inulin as fat replacer on short dough biscuits and their corresponding doughs. A control formulation, with no replacement, and four formulations in which 10, 20, 30, and 40 % of shortening was replaced by inulin were studied. In the dough, shortening was observed surrounding flour components. At higher fat replacement levels, flour was more available for hydration leading to significant (P<0.05) harder doughs: from 2.76 (0.12)N in 10 % fat-replaced biscuits to 5.81 (1.56)N in 30 % fat-replaced ones. Biscuit structure was more continuous than dough structure. A continuous fat layer coated the matrix surface, where starch granules were embedded. In general, weight loss during baking and water activity decreased significantly (P<0.05) as fat replacement increased. Biscuit dimensions and aeration decreased when fat replacement increased, e.g., width gain was +1.20 mm in 10 fat-replaced biscuits and only +0.32 mm in 40 % fat-replaced ones. Panelist found biscuits with 20 % of fat replacement slightly harder than control biscuits. It can be concluded that shortening may be partially replaced, up to 20 %, with inulin. These low fat biscuits are similar than the control biscuits, and they can have additional health benefits derived from inulin presence.

Functionality of several cake ingredients: a comprehensive approach

The roles of some cake ingredients – oil, a leavening agent, and inulin – in the structure and physicochemical properties of batter and cakes were studied in four different formulations. Oil played an important role in the batter stability, due to its contribution to increasing batter viscosity and occluding air during mixing. The addition of the leavening agent was crucial to the final height and sponginess of the cakes. When inulin was used as a fat replacer, the absence of oil caused a decrease in the stability of the batter, where larger air bubbles were occluded. Inulin dispersed uniformly in the batter could create a competition for water with the flour components: gluten was not properly hydrated and some starch granules were not fully incorporated into the matrix. Thus, the development of a continuous network was disrupted and the cake was shorter and softer; it contained interconnected air cells in the crumb, and was easily crumbled. The structure studies were decisive to understand the physicochemical properties.

Commercial thickeners used by patients with dysphagia: rheological and structural behaviour in different food matrices

In order to achieve a safe swallowing in patients with dysphagia, liquids must be thickened. In this work, two commercial starch based thickeners dissolved in water, whole milk, apple juice and tomato juice were studied. The thickeners were Resource®, composed of modified maize starch and Nutilis®, composed of modified maize starch and gums. They were formulated at two different concentrations corresponding to nectar- and pudding-like consistencies. Influence of composition, concentration and food matrix on rheological properties and structure of the resulting pastes were analysed. Viscoelastic measurements and microscopic observations of the thickeners dissolved in water revealed structural differences due to the presence of gums. When the thickeners were dissolved in the other food matrices significant statistical interactions were found between the matrix and the thickener-type in both the viscoelastic and flow parameters. The most relevant differences were observed for the nectar-like consistency with Nutilis® thickener in milk and apple juice. These samples had lower zero viscosity values and higher loss tangent values, that corresponded to weaker structured systems. Light microscopy images showed that the matrix formed by swollen starch granules was interrupted by the presence of gums. The structure of the matrices in pudding-like formulations became more continuous irrespectively of the matrix employed, and also differences in viscoelasticity among samples diminished. Although differences were observed in zero shear viscosity values among samples, the viscosity of the beverages at 50 s−1 – commonly used as a reference for swallowing – was similar for all samples regardless of the matrix used.

HOST-MEDIATED INDUCTION OF alpha-AMYLASES BY LARVAE OF THE MEXICAN BEAN WEEVIL Zabrotes subfasciatus (COLEOPTERA: CHRYSOMELIDAE: BRUCHINAE) IS IRREVERSIBLE AND OBSERVED FROM THE INITIATION OF THE FEEDING PERIOD

Larvae of Zabrotes subfasciatus secrete alpha-amylases that are insensitive to the alpha-amylase inhibitor found in seeds of Phaseolus vulgaris. By analyzing amylase activities during larval development on P. vulgaris, we detected activity of the constitutive amylase and the two inducible amylase isoforms at all stages. When larvae were transferred from the non alpha-amylase inhibitor containing seeds of Vigna unguiculata to P. vulgaris, the inducible alpha-amylases were expressed at the same level as in control larvae fed on P. vulgaris. Interestingly, when larvae were transferred from seeds of P. vulgaris to those of V. unguiculata, inducible alpha-amylases continued to be expressed at a level similar to that found in control larvae fed P. vulgaris continuously. When 10-day-old larvae were removed from seeds of V. unguiculata and transferred into capsules containing flour of P. vulgaris cotyledons, and thus maintained until completing 17 days ( age when the larvae stopped feeding), we could detect higher activity of the inducible alpha-amylases. However, when larvae of the same age were transferred from P. vulgaris into capsules containing flour of V. unguiculata, the inducible alpha-amylases remained up-regulated. These results suggest that the larvae of Z. subfasciatus have the ability to induce insensitive amylases early in their development. A short period of feeding on P. vulgaris cotyledon flour was sufficient to irreversibly induce the inducible alpha-amylase isoforms. Incubations of brush border membrane vesicles with the alpha-amylase inhibitor 1 from P. vulgaris suggest that the inhibitor is recognized by putative receptors found in the midgut microvillar membranes. (C) 2010 Wiley Periodicals, Inc.