Influence of particle size on protein extractability from soybean and okara

Nitrogen Solubility Index (NSI) of okara was 38 which was only about half of soybean (71). Maximum protein recovery of 97.0% and 93.4% was achieved with soybean and okara flour from their respective fine fractions (<75 μm) in a three-step-sequential extraction. Recovery of protein from unclassified primary ground flour of soy and okara was much lower compared to their corresponding fine fractions (particle size <75 μm). Secondary grinding of coarse fraction improved the overall protein recovery to an extent of 3.3% in okara and to a much larger extent of 6.8% in soybean. Results showed that a two-step sequential extraction with respective solid-to-solvent (w/v) ratios of 1:20 and 1:10 was suitable in terms of protein recovery. Protein recovery from soy granules and okara flakes improved by 30.6% and 6.9%, respectively with the introduction of primary and secondary grinding steps indicating the benefits of the proposed approach for practical applications.     

我国大豆加工利用研究的综合分析

本文对我国大豆加工利用的历史、现状进行了分析，总结了我国大豆加工利用的基础、现实发展水平和存在的主要问题，并对大豆加工利用的研究趋势进行了展望，为以后的大豆综合利用、深加工提供了借鉴。     

Effects of roasting,powdering and storing irradiated soybeans on hydrocarbon detection for identifying post-irradiation of soybeans

Hydrocarbons, which are produced by irradiation of lipid-containing foods, were analyzed in irradiated soybeans, which were roasted, powdered and stored, to determine whether these treatments affect hydrocarbon detection for identifying post-irradiation of soybeans. Soybeans were irradiated (Irr), irradiated and roasted (Irr–Rst), roasted and irradiated (Rst–Irr), irradiated, roasted and powdered (Irr–Rst–Pwd), and roasted, powdered and irradiated (Rst–Pwd–Irr). They were stored at refrigerated or room temperature for 30 weeks. Oils were extracted using hexane and Na₂SO₄. Hydrocarbon fraction was separated through a Florisil column and analyzed using GC. Hydrocarbons 17:2, 16:3, 17:1 and 16:2 were not detected in non-irradiated soybeans and soybean powder, but they were detected in those irradiated at 0.5 kGy or higher. The levels of the hydrocarbons increased with dose. The hydrocarbon levels in the Irr–Rst, Rst–Irr, and Irr–Rst–Pwd soybeans were little different from those in the Irr soybeans. Hydrocarbon detection in the Rst–Pwd–Irr soybean powder showed a slightly different pattern from those in the other treatments. Hydrocarbon levels in the soybean and soybean powder samples stored at refrigerated temperature for 30 weeks changed little, compared to initial samples. The hydrocarbon detection patterns in the samples stored at room temperature for 30 weeks were similar to the initial and refrigerated samples with slightly lower detection levels in the room-stored samples.     

Polyphenolic content and antioxidant activity of Eugenia pollicina leaf extract in vitro and in model emulsion systems

The polyphenolic profile of a leaf extract of the Mauritian endemic plant, Eugenia pollicina, was assessed as a source of natural antioxidants. The amounts of flavan-3-ol derivatives determined by HPLC, were in the order of (−)-epicatechin (EC) > (−)-epigallocatechin gallate (EGCG) > (+)-catechin (C) > (−)-epicatechin gallate (ECG) with the levels of Procyanidin B2 and B1 dimers ranging from 1 to 3 mg g⁻¹ FW. The trolox equivalent antioxidant capacity and ferric reducing antioxidant power values were 796 ??mol g⁻¹ FW and 302 ??mol g⁻¹ FW respectively. E. pollicina extracts also strongly inhibited the FeCl₃ and ascorbate-dependent microsome lipid peroxidation, a function that is linked to their flavonoid contents. The extent of DNA damage induced by the extract under study in the copper-phenanthroline assay was lower than the effect of a reference of 240 ??M ascorbate. E. pollicina extracts also inhibited lipid autoxidation in the 30% (v/v) olive oil and soybean oil oil-in-water (O/W) emulsions and was effective in slowing down the formation of hydroperoxides in the emulsions during 13 days storage at 40 °C as determined by the peroxide, conjugated diene and para-anisidine values. The high levels of total phenolics, flavonoids and procyanidins measured indicate that E. pollicina is a potential source of antioxidants relevant to the maintenance of oxidative stability of the food matrix, cosmetics and/or pharmaceutical preparations.     

大豆肽体外抗氧化效果的研究

研究采用酶解、超滤等方法制备的大豆肽的还原能力抗氧化能力及对·OH的清除作用,结果表明大豆肽的抗氧化能力随浓度的增加而增强,在一定浓度范围内,大豆肽具有较强的清除·OH的效果,此外,大豆肽无助氧化作用。     

高纯度大豆卵磷脂制备研究

对从大豆油脚制备高纯度卵磷脂工艺进行了研究。提出了用吸附剂、微滤膜去色、除杂,用金属盐沉淀剂除去脑磷脂的新工艺,从而使产品中卵磷脂含量达到85%以上,同时,着重研究了丙酮脱油时pH值对磷脂回收率的影响,使磷脂损失率降到最低水平。并确定了丙酮脱油制取粉末磷脂时的最低丙酮浓度,为降低工业化生产粉末磷脂的成本提供了依据。     

虎杖天然染料提取及对大豆蛋白织物染色

对虎杖天然染料提取及其在大豆蛋白织物上的染色性能进行探讨.实验结果表明:虎杖天然染料色泽随pH值变化而改变,其合适的染色工艺参数为pH 4～6,温度95℃,时间60 min;经过不同媒染剂处理后,大豆蛋白织物呈现出不同的色泽;未经固色处理色牢度一般,而经固色剂处理后色牢度可达到3级或3级以上.     

大豆卵磷脂的提纯

探讨了以市售大豆油脚为原料,用全溶剂法精制出符合药用规格的大豆卵磷的工艺条件并建立了相应的数学模型。其主要性能指标为：Ｎ％＝１．７０．Ｐ％＝４．０％,酸价１０．４８,碘价９５．３５。     

A Two-Step Filtering approach for detecting maize and soybean phenology with time-series MODIS data

The crop developmental stage represents essential information for irrigation scheduling/fertilizer management, understanding seasonal ecosystem carbon dioxide (CO₂) exchange, and evaluating crop productivity. In this study, we devised an approach called the Two-Step Filtering (TSF) for detecting the phenological stages of maize and soybean from time-series Wide Dynamic Range Vegetation Index (WDRVI) data derived from Moderate Resolution Imaging Spectroradiometer (MODIS) 250-m observations. The TSF method consists of a Two-Step Filtering scheme that includes: (i) smoothing the temporal WDRVI data with a wavelet-based filter and (ii) deriving the optimum scaling parameters from shape-model fitting procedure. The date of key crop development stages are then estimated by using the optimum scaling parameters and an initial value of the specific phenological date on the shape model, which are preliminary defined in reference to ground-based crop growth stage observations. The shape model is a crop-specific WDRVI curve with typical seasonal features, which were defined by averaging smoothed, multi-year WDRVI profiles from MODIS 250-m data collected over irrigated maize and soybean study sites.In this study, the TSF method was applied to MODIS-derived WDRVI data over a 6-year period (2003 to 2008) for two irrigated sites and one rainfed site planted to either maize or soybean as part of the Carbon Sequestration Program (CSP) at the University of Nebraska-Lincoln. A comparison of satellite-based retrievals with ground-based crop growth stage observations collected by the CSP over the six growing seasons for these three sites showed that the TSF method can accurately estimate the date of four key phenological stages of maize (V2.5: early vegetative stage, R1: silking stage, R5: dent stage and R6: maturity) and soybean (V1: early vegetative stage, R5: beginning seed, R6: full seed and R7: beginning maturity). The root mean square error (RMSE) of phenological-stage estimation for maize ranged from 2.9 [R1] to 7.0 [R5] days and from 3.2 [R6] to 6.9 [R7] days for soybean, respectively. In addition, the TSF method was also applied for two years (2001 and 2002) over eastern Nebraska to test its ability to characterize the spatio-temporal patterns of these key phenological stages over a larger geographic area. The MODIS-derived crop phenological stage dates agreed well with the statistical crop progress data reported by the United State Department of Agriculture (USDA) National Agricultural Statistics Service (NASS) for eastern Nebraska's three crop agricultural statistic districts (ASDs). At the ASD-level, the RMSE of phenological-stage estimation ranged from 1.6 [R1] to 5.6 [R5] days for maize and from 2.5 [R7] to 5.3 [R5] days for soybean.