Effects of fruit bagging on coloring and related physiology,and qualities of red Chinese sand pears during fruit maturation

Red Chinese sand pears (Pyrus pyrifolia Nakai) are particular to China. In order to determine the effects of fruit bagging treatments (including bag types, bag removal patterns and dates) on fruit qualities and to understand the mechanism of coloring of red Chinese sand pears, two experiments were carried out. In the first experiment, fruit of ‘Meirensu’ were firstly covered by light-impermeable paper bags with different levels of light permeable liners during their early development stage, then, the whole bag were/not removed or only the outer layer of bags were removed 3, 2 or 1 weeks before harvest. Thus, the fruit were/not totally re-exposed or were under different levels of sunlight transmission (80.31% or 34.71%). Non-bagged fruit were used as the control. Bagging treatments significantly affected the concentration of anthocyanin and the visual qualities of pear fruit. Compared to control, fruit re-exposed totally for 2 or 3 weeks accumulated the largest amount of anthocyanin and fruit receiving 80.31% and 34.71% of sunlight for 1–3 weeks could synthesize a little anthocyanin, indicating that high light intensity is imperative for coloring in red Chinese sand pears. Bagging treatments did not affect contents of total soluble sugars, but decreased organic acids contents in fruit. In the second experiment, fruit of ‘Meirensu’ and ‘Yunhongli No. 1’ were covered with only one type of light-impermeable bag during the early development stage and totally re-exposed after the bag removal 15 days before harvest. Fruit were then collected at different intervals to trace the time-course of coloring, and related physiology and inner qualities. With increasing time after the bag removal, the concentration of chlorophyll, carotenoid, flavonoid and total phenols changed little, but the concentration of anthocyanin accumulated extremely fast within 10 days after the bag removal in both cultivars and thereafter kept constant. ‘Yunhongli No. 1’ had higher anthocyanin contents and lower hue angle than ‘Meirensu’, indicating a higher potential of anthocyanin synthesis. After the bag removal, the sucrose contents and PAL activities increased gradually and correlation analysis revealed that they were highly correlated with anthocyanin accumulation in two cultivars. This study suggests that anthocyanin biosynthesis in red Chinese sand pears is a highly light dependent process and modified by genotypes. Based on the current results, in order to obtain red Chinese sand pear fruit with attractive appearance and good inner qualities, fruit must be covered with light-impermeable bags at the early stage of fruit development and the bag should be removed totally at least 10 days before harvest.     

Mineralization of “non‐metabolizable” glucose analogues in soil: potential chemosensory mimics of glucose

Glucose is widely used to study the dynamics of easily available organics in soil. Pure culture studies have revealed that many microorganisms can sense and respond to glucose through chemosensory mechanisms that are not directly reliant on energy catabolism. However, the rapid mineralization of glucose by microorganisms makes it difficult to disentangle its energy effects from such non‐catabolic interactions. “Non‐metabolizable” glucose analogues have proven useful in mechanistic studies of glucose in pure culture, but have never been applied to complex microbial communities in soil. We sought to determine how their mineralization in soil differs from that of glucose, and whether they have potential as a new approach for investigating chemosensory mechanisms in soil microbiology. We incubated soil from an agricultural Haplic Luvisol under controlled conditions for 24 d and monitored CO₂ efflux after addition of (1) glucose, and three “non‐metabolizable” glucose analogues: (2) 2‐deoxyglucose (DG), (3) α‐methylglucoside (αMG), and (4) 3‐O‐methyl‐glucose (OMG), at three concentration levels, along with a control. All three analogues did in fact produce a large increase in soil CO₂ efflux, but the dynamics of their mineralization differed from the rapid degradation seen for glucose. At medium and high concentrations, CO₂ efflux peaked between 2.5 and 4 d after amendment with DG and αMG, and was delayed by about one week for OMG. The markedly different patterns of mineralization between glucose and OMG offer a new tool for investigating the behavior of glucose in soil. By using OMG as a glucose model, chemosensory mechanisms could be studied with limited interference from energy catabolism.     

Effects of coppicing on the root and stump carbohydrate dynamics in birches

Whole birch stems were cut off in order to determine how coppicing affects root and stump starch, glucose, fructose and sucrose concentrations and their correlation with shoot regeneration capacity. The Betula pubescens Ehrh. and B. pendula Roth studied included intact trees, trees that had been coppiced 8 years earlier, trees coppiced at the beginning of the experimental season, and birches that had been coppiced twice, 8 years earlier and at the beginning of the experimental season. Carbohydrate accumulation differed between 8 years earlier coppiced and intact trees. Recent coppicing clearly decreased the starch and sugar concentrations of the roots, which were often highest in the thin roots. The concentrations of these compounds in the stumps were always low, although the carbohydrate concentrations of stumps, in particular, correlated with shoot regeneration capacity. Starch was the most labile of the carbohydrates measured and most clearly reacted to coppicing. Differences in starch- and sugar-reserve dynamics indicate a difference between these birch species in the use and replenishing of root and stump reserves. This information may also be of help when the effects of other stresses, for example, severe animal damage or burning, on the regrowth of young birch stands are estimated.     

Reducing the potential for processing contaminant formation in cereal products

Processing contaminants may be defined as substances that are produced in a food when it is cooked or processed, are not present or are present at much lower concentrations in the raw, unprocessed food, and are undesirable either because they have an adverse effect on product quality or because they are potentially harmful. The presence of very low levels of processing contaminants in common foods is becoming an increasingly important issue for the food industry, as developments in analytical techniques and equipment bring foods under closer and closer scrutiny. This review considers the formation of lipid oxidation products, hydrogenation of polyunsaturated fatty acids to prevent lipid oxidation and the associated risk of trans fatty acid formation. The formation of acrylamide in the Maillard reaction is described, as well as the genetic and agronomic approaches being taken to reduce the acrylamide-forming potential of cereal grain. The multiple routes for the formation of furan and associated chemicals, including hydroxymethylfurfuryl, are also described. The evolving regulatory and public perception situations for these processing contaminants and their implications for the cereal supply chain are discussed, emphasising the need for cereal breeders to engage with the contaminants issue.     

Growth and Physiological Characteristics of Rice Seedlings Raised with Long Mat by Hydroponics: —Comparison with young seedlings raised in soil—

Summary

Growth and physiological characteristics of rice seedlings raised with long mat by hydroponics (SLH) were compared with those of young seedlings raised in soil (YSS). When SLH and YSS were raised under the similar environmental conditions, the dry weight of shoot in SLH was significantly lighter than that in YSS at the time of seedling harvest, whereas the shoot in SLH was as long as that in YSS. The increase of dry weight of shoot and the decrease of dry weight of grain were smaller in SLH than in YSS during the raising of seedlings. In addition, the content of soluble sugars in the grain of SLH was apparently lower than that of YSS, indicating that the supply of carbohydrates from endosperm to shoot was less in SLH than in YSS. Crop growth rate and mean leaf area index of SLH were lower than those of YSS, while net assimilation rate of SLH was similar to that of YSS. The size of leaf blades in SLH was markedly smaller than that in YSS, whereas no significant difference was observed in the rates of photosynthesis and dark respiration in leaf blades between SLH and YSS. The results suggest that the leaf growth of SLH is reduced by the insufficient supply of carbohydrates from endosperm, and this is the major cause of lower levels of dry matter production in SLH as compared with that in YSS.     

Lipid biosynthesis from [14C]-glucose in the coral Montipora digitata

ABSTRACT:     Glucose has been implicated in functioning as a form of carbon translocated from symbiont zooxanthellae to the host coral cell. The present paper describes the lipid biosynthesis from [¹⁴C]-glucose in the coral tissue. To study the incorporation of [¹⁴C]-glucose into lipids, the branch tips of the coral Montipora digitata were incubated with [¹⁴C]-glucose or another radiolabeled substrates. The lipid biosynthesis from [¹⁴C]-glucose was dependent on light, and was decreased by dark conditions or by photosystem II inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Of the lipid classes, the light dependency was more pronounced with the biosynthesis of triacylglycerols (TG) and wax compared with phospholipids. Examination of [¹⁴C]-label distribution in the glycerolipids suggested that [¹⁴C]-glucose supplied mainly the fatty acid moiety of newly synthesized TG, while [¹⁴C]-glucose provided evenly the fatty acid moiety and the glycerol skeleton of phospholipids. The comparison of [¹⁴C]-labeling of lipid from host coral tissue and symbiont zooxanthellae suggested that [¹⁴C]-glucose entered the coral cell and was processed in parallel in the zooxanthellae and host cells. Furthermore, the coral cells used various [¹⁴C]-labeled sugars for lipid synthesis with similar lipid labeling profile as was the case for glucose. The current study thus supports the view that the low-molecular-weight compound, sugars and amino acids, once translocated from zooxanthellae to host cell were metabolized toward lipogenesis as well as glycerol.     

对蜂蜜中主要抗褐变因子的探讨

选用ＡＧ５０Ｗ－Ｘ８阳离子交换树脂，并以批处理的方式，成功地将蜂蜜中的肽类物质与其它组合得到了分离。抗褐变实验结果清楚地表明，蜂蜜中的肽类成分完全没有抑制褐变的活性。这与以前的报道截然不同。     

含糖类物料的喷雾干燥

从玻璃态转变温度着手,分析了在喷雾干燥中含有不同品种糖类物料粘壁的原因,提出了改性或在设计干燥流程时的6种应对方法。     

Quantitative trait loci (QTL) affecting sugars, organic acids and other biochemical properties possibly contributing to flavor, identified in four advanced backcross populations of tomato

Although the Advanced Backcross strategy has proven very useful for QTL detection in tomato, it has been used mainly in identifying QTL for agronomic traits such as yield, color, etc. Tomato flavor is an important quality characteristic, yet it has been difficult to assess flavor or traits that affect it. In this study the AB-QTL strategy was applied to four advanced backcross populations to identify QTL for biochemical properties that may contribute to the flavor of processed tomatoes, such as sugars and organic acids. A total of 222 QTL were identified for 15 traits, including flavor as assessed by a taste panel. Correlations of certain biochemicals with flavor and possible methods of assessing and improving flavor are discussed. In particular, QTL with very significant effects associated with the ratio of sugars/glutamic acid, a trait highly correlated with improved flavor, have been identified as good targets for future work in improving the flavor of tomatoes. This revised version was published online in August 2006 with corrections to the Cover Date.