Properties of low-moisture viscoplastic materials consisting of oil droplets dispersed in a protein-carbohydrate-glycerol matrix: effect of oil concentration

The influence of oil concentration and baking on the properties of low-moisture composites consisting of oil droplets dispersed in a protein-carbohydrate-glycerol matrix was investigated. These composites were produced by blending canola oil, whey protein concentrate (WPC), corn syrup, and glycerol together using a high-speed mixer. The resulting system consisted of oil droplets dispersed in a polar matrix. Some composites were analyzed directly after preparation, while others were analyzed after being heated at 176 degrees C for 10 min to simulate baking. The "lightness" of the composites was greater before baking (higher L value), but the color was more intense after baking (higher a and b values). The lightness and color intensity of the composites decreased as the oil concentration increased, with the effects being more pronounced in the baked samples. The zeta potential of the oil droplets (measured after dilution at pH 6) was highly negative (approximately -40 mV), indicating that whey protein was adsorbed to the droplet surfaces. The mean particle diameter (measured after dilution at pH 6) increased appreciably after baking, which was attributed to droplet flocculation. The rheological properties of the unbaked and baked materials were characterized by squeezing flow viscometry, which showed that the measurements associated with consistency and yield stress increased with increasing oil concentration and with baking.     

Effect of fruiting body maturity stage on chemical composition and antimicrobial activity of Lactarius sp. mushrooms

The effects of fruiting body maturity on chemical composition and antimicrobial activity of the wild mushrooms, Lactarius deliciosus and Lactarius piperatus, were evaluated. Immature and mature samples were analyzed for proximate constituents (moisture, fat, crude protein, ash, carbohydrates), nutritional value, and individual composition in fatty acids and sugars. Protein content, MUFA (monounsaturated fatty acids), and PUFA (polyunsaturated fatty acids) percentages increased with the fruiting body maturity stage, while carbohydrate and SFA (saturated fatty acids) content decreased. The maturity stage did not significantly affect the individual sugar profile. The antimicrobial activity of the mushrooms was screened against Gram positive and Gram negative bacteria and fungi, and correlated to the amounts of phenols, flavonoids, ascorbic acid, beta-carotene, and lycopene present in the immature and mature fruiting bodies. Mature fruiting bodies with mature spores presented lower antimicrobial activity, which was in agreement with the bioactive compound content found in those samples.     

A new methodology based on GC-MS to detect honey adulteration with commercial syrups

Honey adulterations can be carried out by addition of inexpensive sugar syrups, such as high fructose corn syrup (HFCS) and inverted syrup (IS). Carbohydrate composition of 20 honey samples (16 nectar and 4 honeydew honeys) and 6 syrups has been studied by GC and GC-MS in order to detect differences between both sample groups. The presence of difructose anhydrides (DFAs) in these syrups is described for the first time in this paper; their proportions were dependent on the syrup type considered. As these compounds were not detected in any of the 20 honey samples analyzed, their presence in honey is proposed as a marker of adulteration. Detection of honey adulteration with HFCS and IS requires a previous enrichment step to remove major sugars (monosaccharides) and to preconcentrate DFAs. A new methodology based on yeast (Saccharomyces cerevisiae) treatment has been developed to allow the detection of DFAs in adulterated honeys in concentrations as low as 5% (w/w).     

Inheritance of Aluminum Tolerance and its Effects on Grain Yield and Grain Quality in Oats (Avena Sativa L.)

Summary Aluminum toxicity due to the cation Al⁺³ is a major factor limiting yields in acid soils. Wide genetic variability to aluminum tolerance is found in oat genotypes. The objectives of this study were to determine the number of genes controlling aluminum tolerance in oats and to verify if any detrimental effects were present of the aluminum tolerance genes on grain yield and grain quality in Al⁺³free soils. Aluminum tolerance was estimated as the average regrowth of the main root after exposure to toxic levels of Al⁺³ in a hydroponic solution under controlled conditions. The number of genes controlling that trait was estimated from the distribution of the average root regrowth frequencies in a population of 333 recombinant inbred lines (RIL's) in generations F_5:6 and F_5:7. The effects on grain yield and grain quality were assessed in a subpopulation of 162 RIL's chosen based on their aluminum tolerance response. Aluminum tolerance in the evaluated population was controlled by one dominant major gene with the tolerant genotypes carying Al _a Al _a and the sensitive ones al _a al _a alleles. No detrimental effects of the Al _a allele on grain yield or grain quality were detected.Part of the Master of Science dissertation of the first author     

利用短波红外高光谱成像技术检测洋葱酸皮病(Burkholderia cepacia)

酸皮病是一种重要的洋葱采后病害,对洋葱的采后生产造成了巨大的经济损失。本研究利用短波红外高光谱成像系统对洋葱采后酸皮病进行检测,分别从健康的和已感染酸皮病的洋葱上采集高光谱反射图像(950~1 650 nm),通过对两种洋葱的光谱进行主成分分析的结果表明,洋葱的颈部区域在1 070、1 400 nm波长下对酸皮病的发生最具指示性。采用两种最佳波长下获得的对数比率图像对两种不同的图像进行分析研究。第一种分析方法是利用全局阈值(0.45)将感染酸皮病的图像区域从对数比率图像中分离出来,通过对分离图像区域的象元素进行Fisher判别分析,可辨别出80%感染酸皮病的洋葱。第二种分析方法是从对数比率图像上获得三个参数(最大值、对比度及匀质性),再将这三个参数作为输入特征向量导入到支持向量机(Gaussian kernel,γ=1.5)中,利用这种方法,可辨别出87.14%感染酸皮病的洋葱。应用本研究结果可进一步开发出一种多光谱成像系统,用于洋葱包装流水线上酸皮病的检测。     

A QTL controlling low temperature induced spikelet sterility at booting stage in rice

Low temperature is a major abiotic stress for rice cultivation, causing serious yield loss in many countries. To identify QTL controlling low temperature induced spikelet sterility in rice, the progeny of F2, BC1F1 and BC2F1 populations derived from a Reiziq × Lijiangheigu cross were exposed to 21/15°C for 15 days at the booting stage, and spikelet sterility was assessed. For genotyping, 92 polymorphic markers from 373 SSR and 325 STS primer pairs were used. A major QTL was initially indentified on the short arm of chromosome 10 by selective genotyping using highly tolerant and susceptible progeny from F2 and BC1F1 populations. The QTL (qLTSPKST10.1) was validated and mapped by genotyping the entire F2 (282 progeny) and BC1F1 (84 progeny) populations. The results from the F2 population showed that qLTSPKST10.1 could explain 20.5% of the variation in spikelet sterility caused by low temperature treatment with additive (a = 14.4) and dominant effect (d = −7.5). From the analysis of 98 selected BC2F1 progeny, the QTL located in the 3.5 cM interval between S10010.9 and S10014.4 was further confirmed. Based on the studies of 3 generations in 2 years, it was clear that the QTL on chromosome 10 is a major determinant of the control of low temperature induced spikelet sterility at booting stage.     

Defining the validity of a biochemical index of soil quality

 The native soils of Galicia (NW Spain) exhibit a biochemical equilibrium such that total soil N is a function of five biochemical and microbiological parameters: microbial biomass C, mineralized N, phosphomonoesterase, β-glucosidase and urease activities. To investigate whether the ratio of the total N calculated from biochemical soil properties (Nc) and the total N as measured by the Kjeldahl method (Nk; Nc/Nk) can be used as an index of soil quality, we determined these variables and consequently the ratio in three kinds of disturbed soils: an artificially Cu-contaminated soil, two lignite mine soils, and a number of arable soils. In none of the studied soils did the individual biochemical parameters respond consistently to the factors influencing soil quality, but in all cases soil degradation was reflected by the Nc/Nk value, which differed more or less markedly from 100%. Nc/Nk can therefore be used for the rapid evaluation of soil degradation, since it distinguishes among biochemically balanced soils, soils in a transient state of high microbiological and biochemical activity and degraded soils. It can also serve as a reliable basis for the rapid calculation of the "ecological dose" (ED₅₀) of soil pollutants. The use of Nc/Nk as an objective index of the biochemical quality of soils is recommended. Received: 20 December 1998     

Adsorption of whey protein isolate at the oil-water interface as a function of processing conditions: a rheokinetic study

In this paper we present surface dynamic properties (interfacial tension and surface dilational properties) of a whey protein isolate with a high content of beta-lactoglobulin (WPI) adsorbed on the oil-water interface as a function of adsorption time. The experiments were performed at constant temperature (20 degrees C), pH (5), and ionic strength (0.05 M). The surface rheological parameters and the interfacial tension were measured as a function of WPI concentration (ranging from 1 x 10(-)(1) to 1 x 10(-)(5)% w/w) and different processing factors (effect of convection and heat treatment). We found that the interfacial pressure, pi, and surface dilational modulus, E, increase and the phase angle, phi, decreases with time, theta, which should be associated with WPI adsorption. These phenomena have been related to diffusion of the protein toward the interface (at short adsorption time) and to the protein unfolding and/or protein-protein interactions (at long-term adsorption) as a function of protein concentration in solution and processing conditions.     

1-methylcyclopropene increases storability and shelf life in climacteric and nonclimacteric plums

The effect of 1-methylcyclopropene (1-MCP) at three different doses (0.25, 0.50, and 0.75 microL L(-1)) on the ripening processes of a climacteric, cv. Santa Rosa, and a suppressed climacteric type, cv. Golden Japan, plum was studied. For both cultivars, positive effects were observed in terms of inhibition of ethylene production and delays of the physical, chemical, and biochemical changes associated with ripening. 1-MCP-treated plums were firmer with lower weight loss, reduced degrees Brix/titratable acidity ratios, and lower color changes during cold storage and subsequent shelf life at 20 degrees C than controls. For most factors, the effectiveness of 1-MCP was dose-dependent in Santa Rosa but dose-independent for Golden Japan.     

Influence of harvest date and crop yield on the fatty acid composition of virgin olive oils from cv. Picual

In this study was analyzed the effect of crop year and harvesting time on the fatty acid composition of cv. Picual virgin olive oil. The study was carried out during the fruit ripening period for three crop seasons. The mean fatty acid composition of Picual oils was determined. The oils contained palmitic acid (11.9%), oleic acid (79.3%), and linoleic acid (2.95%). The content of palmitic acid and saturated fatty acids decreased during fruit ripening while oleic and linoleic acids increased. The amount of stearic and linolenic acids decreased. The amount of saturated acids, palmitic and stearic, and the polyunsaturated acids linoleic and linolenic was dependent on the time of harvest, whereas the amount of oleic acid varied with the crop year. The differences observed between crop years for both palmitic and linoleic acid may be explained by the differences in the temperature during oil biosynthesis and by the amount of summer rainfall for oleic acid content. A significant relationship was observed between the MUFA/PUFA ratio and the oxidative stability measured by the Rancimat method.