Solubilized wheat protein isolate: functional properties and potential food applications

Solubility, foaming capacity/stability, water holding and fat absorption capacities, and emulsifying capacity/stability of a solubilized wheat protein isolate (SWPI) were compared with those of commercial protein, that is, sodium caseinate (NaCAS), dried egg white (DEW), nonfat dry milk (NFDM), and soy protein isolate (SPI). SWPI was highly soluble at pH 6.5-8.5. Foaming capacity of SWPI was superior to those of SPI, NFDM, and DEW, and its foaming stability was similar to those of the commercial proteins. Foaming properties of SWPI were greatly improved in the presence of 0.5% (w/v) CaCl(2). Water holding capacity of SWPI was greater than that of NaCAS, NFDM, and DEW, whereas its fat absorption capacity was comparable to that of SPI, NaCAS, and DEW. SWPI exhibited emulsifying properties similar to those of SPI. SWPI was incorporated at 5, 10, 15, or 20% into ice cream, chocolate chip cookies, banana nut muffins, and hamburger patties. Products containing <5% SWPI were acceptable to consumers.     

Functional Attributes of Proteins Withdrawn from Different Stages of a Commercial Ethanol Fuel/Distillers Dried Grains with Solubles Process Using a Wheat Feedstock

The functional attributes of proteins withdrawn from different stages of a commercial ethanol fuel/distillers dried grains with solubles (DDGS) process that used a wheat feedstock were investigated. Specifically, protein coproducts were examined postliquefaction (PL), postdistillation (PD), and postdrying (DDGS) and related to those from the native wheat feedstock (WF). Water hydration, oil holding, foaming, and emulsifying properties of all materials were assessed. The WF and the PL coproduct showed similar water hydration capacities (WHCs), ranging between 80 and 110%, whereas WHCs for the PD and DDGS coproducts were significantly higher (ranging between 264 and 356%). WHC for all products was found to be independent over the pH range of 2.00–10.00. A similar trend was found for the oil holding capacities, for which both WF and PL materials showed lower values (≈120%) than both the PD (203%) and DDGS (171%) materials. Foam capacity and stability for the WF were found to be 32.8 and 61.4%, respectively, whereas no coproducts were foam forming. Emulsion stability decreased from ≈45% for the WF to <10% in all other materials. Findings indicated that initial changes to the protein's functional attributes occurred in the PL stage of ethanol/DDGS processing.     

Functional properties of purified vicilins from cowpea (Vigna unguiculata) and pea (Pisum sativum) and cowpea protein isolate

The major storage globulins (vicilins) of cowpea (Vigna unguiculata) and pea (Pisum sativum) seeds were purified by ammonium sulfate precipitation, and a semipurified cowpea protein isolate (CPI) was prepared by isoelectric precipitation. Some of the functional properties of these proteins, including solubility, foaming, and emulsifying capacities, were investigated and compared. The solubility of purified cowpea vicilin was reduced at pH 5.0, increasing markedly below and above this value. Pea vicilin exhibited poor solubility between pH 5.0 and pH 6.0, and CPI was little soluble in the pH range from 4.0 to 6.0. At neutral pH, the emulsifying activity indexes (EAI) of purified pea vicilin and CPI were 194 and 291 m(2)/g, respectively, which compare quite favorably to EAIs of 110 and 133 m(2)/g for casein and albumin, respectively. Remarkably, purified cowpea vicilin exhibited an EAI of 490 m(2)/g, indicating a very high emulsifying activity. Purified cowpea and pea vicilins exhibited lower foaming capacities and foam stablity indexes (FSI) than CPI. FSI values of 80 and 260 min were obtained for purified pea and cowpea vicilin, respectively, whereas a FSI value of 380 min was obtained for CPI. These results are discussed in terms of the possible utilization of purified vicilins or protein isolates from pea and cowpea in the food processing industry.     

Functional Properties of Rice Bran Protein Isolate at Different pH Levels

The functional properties of proteins from Tarom and Shiroodi cultivars were determined and compared with technological aspects of food and nutraceutical applications. Shiroodi has higher protein content than Tarom, and the yields of protein obtained were 72.88 and 66.36%, respectively. Nitrogen solubilities of rice bran protein of Tarom were more than Shiroodi at all pH levels. In addition, higher solubility was found in acidic or alkaline conditions. Although the rice bran proteins had lower emulsifying properties than bovine serum albumin, they had similar foaming properties in comparison with egg white. Tarom isolates had a significantly higher solubility, emulsifying property, and foaming stability and greater surface properties than Shiroodi isolates. The results showed the surface hydrophobicities of rice bran protein were greater than casein and ovalbumin and lower than other proteins such as bovine serum albumin. Water and oil absorption capacities were 1.03 and 1.66 for Tarom and 87.3 and 75.3 for Shiroodi, respectively. The bulk densities of Tarom and Shiroodi were also 0.55 and 0.53 g/mL, which make them suitable for weaning food and other industrial applications. As a result, these rice bran proteins showed higher hydrophobicity than that of other rice bran protein varieties as well as more functionality. Thus, they have good potential in the food and pharmaceutical industries.     

Effects of high hydrostatic pressure on some functional and nutritional properties of soy protein isolate for infant formula

The effects and mechanism of high hydrostatic pressure (HHP) on some functional and nutritional properties of soy protein isolate (SPI) for infant formula were investigated. Results indicated that solubility, water holding capacity, emulsification activity index, and foaming capacity were improved at lower pressure and time levels, whereas these properties declined at higher levels. However, the emulsification stability index dropped when the pressure increased and the foaming stability decreased with pressure and time levels rising. HHP-treated SPI gave better swallowing properties and in vitro digestibility than control. The hardness, adhesive force, and springiness of SPI gels increased with increaded pressure and elongated time, being lower than those of the control. Near UV circular dichroism spectra confirmed the alteration of tertiary and/or quaternary conformations caused by HHP. Sodiumdoecyl sulfate polyacrylamide gel electrophoresis results indicated that β-conglycinin was more pressure labile than glycinin, and high molecular weight subunits formed via disulfide linkage at higher treatment levels.     

Relationships between different hydration properties of commercial and laboratory soybean isolates

Functional properties related to water protein interactions of soy protein isolates depend on the structural and aggregation characteristics of their major components (storage globulins 7S and 11S) that could be modified by the preparation procedure, thermal and/or chemical treatments, and drying methods. Commercial and laboratory isolates with different functionalities resulting from their structural modifications were compared. Isolates with high solubility or excessive thermally induced insolubilization or compact calcium-induced aggregates caused low water-imbibing capacity (WIC) values. The highest WIC results from the balance between intermediate solubility and the formation of aggregates with good hydration properties. The apparent viscosity of dispersions of commercial (spray dried) and laboratory (lyophilized) isolates depends on the WIC, the morphology and size of the particles, and the interaction of the hydrated particles. The hydration properties and viscosity of protein isolate suspensions were strongly determined by the amount and properties of the insoluble fraction.     

高压微射流压力对大豆蛋白-大豆多糖体系功能性质的影响

为提升大豆分离蛋白（soy protein isolate,SPI）的功能性质,该文引入大豆可溶性多糖（soybean soluble polysaccharides,SSPS）,构建大豆分离蛋白-大豆可溶性多糖体系（SPI-SSPS）,研究动态高压微射流（dynamic high-pressure microfluidization,DHPM）处理对SPI-SSPS功能特性的影响。分别采用0,60,100,140和180 MPa的 DHPM压力处理SPI-SSPS,探究不同压力对SPI-SSPS起泡特性、乳化特性、溶解性、粒度分布和表面疏水性的影响。结果表明,DHPM处理能提高SPI的溶解性和起泡特性,且SSPS的存在能显著提高DHPM对SPI功能性质的改善效果（P<0.05）。100和60 MPa的DHPM处理能使SPI-SSPS呈现较高的起泡能力和起泡稳定性,分别为未处理样品的1.2和2.4倍。140 MPa的DHPM处理使SPI-SSPS溶解性较强,为未处理样品的1.8倍。然而,DHPM处理会显著降低SPI-SSPS的乳化特性、粒径和表面疏水性（P<0.05）。随着处理压力的增加,SPI-SSPS的粒度和表面疏水性逐渐降低,在180MPa的DHPM处理下SPI-SSPS具有较小的粒径和较低的荧光强度。综上所述,DHPM结合SSPS改性技术可用于改善SPI的功能性质（如溶解性、起泡性）,促进SPI在食品工业的应用。该文的研究结果可为SPI的功能性质改性提供参考。     

Symbiotic efficiency and compatibility of native rhizobia in northern Thailand with different soybean cultivars

Symbiotic efficiency and compatibility of 81 isolates of native bradyrhizobia from irrigated areas in northern Thailand with four soybean cultivars and one cowpea cultivar were evaluated under laboratory conditions. Effectiveness and / or compatibility of the tested isolates were compared with those of a standard strain (Bradyrhizobium japonicum CB 1809) by using plants grown on plastic seed bags. Effectiveness of the isolates was also estimated using uninoculated control plants grown in a nitrogen-free solution. Nodulation of a wide range of host plants by the majority of the tested isolates was observed, which agreed well with the results of our previous field experiment (Shutsrirung et al. 2002: Soil Sci. Plant Nutr., 48, 491–499). Up to 75% of the tested isolates induced a higher growth efficiency than that of the uninoculated control in association with one of the tested cultivars, Black soybean. Comparision with uninoculated control plants, enable to estimate the proportion of the tested isolates leading to effective growth promotion (E + e) of each cultivar, namely, Black soybean (local Thai cultivar), 75%; Cowpea, 82%; SJ5 (commercial Thai cultivar), 33%; Bragg (US cultivar), 33%; and Improved Pelican (US cultivar), 9%. These results indicated that although isolates with a high infectiveness with both “Asian-type” and “US-type” soybeans could be found, a high frequency of isolates leading to inefficient nodules was observed in the US cultivar, suggesting the presence of genetic differences in the soybean cultivars that express high-preference (efficient nodules) or low-preference (inefficient nodules) for a certain group of tested isolates. Based on the results of this laboratory experiment together with our previous field experiment, native rhizobial populations in the irrigated area of northern Thailand could be separated into three groups; Group 1: rhizobium strains showing a high effectiveness with only Asian cultivars, Group 2: strains showing a high effectiveness with only US origin cultivars, and Group 3: strains showing a high effectiveness with both Asian and US origin cultivars. The majority of the native rhizobial populations belonged to Group 1. The isolates in Group 3 may display a high potential for manipulating useful rhizobial inoculant.     

Differences in Carbohydrate Composition and Digestion In Vitro of Selected Barley Cultivars as Influenced by Pearling and Cooking

Among common cereals, barley is a low glycemic index food. In an attempt to better understand this character, the nutritional properties of glycemic carbohydrates and dietary fiber concentrations of nine cultivars were evaluated. The cultivars were selected based on botanical variations and commercial value to investigate the impact of pearling and cooking on nutritional properties. Each cultivar was pearled into four fractions ranging from hull removal only to hull, bran, germ, and crease removal. The study showed that botanical class and degree of pearling significantly affect the carbohydrate composition and digestion indices of barley. Waxy starch cultivars had less total starch and more rapidly digestible starch (RDS), rapidly available glucose (RAG), and β‐glucan than the other nonwaxy cultivars. Regardless of the barley type, the less pearled kernels had significantly lower total starch and higher total low molecular weight sugars, insoluble, and total fiber. However, β‐glucan content was fairly comparable in the whole grain and pearled fractions. Cooking had a significant effect on nutritional properties of Celebrity and AC Klinck cultivars. The only consistent significant difference between raw and cooked barley was resistant starch (RS), which increased after cooking regardless of cultivar or fraction. The study showed that barley cultivar and carbohydrate composition significantly affected starch digestion with some cultivar fractions holding a promise for the development of low glycemic index foods.     

不同制备方法对花生蛋白功能性质的影响(简报)

该文研究了不同制备方法对花生浓缩蛋白功能性的影响,以期为不同制备方法制得的花生浓缩蛋白在食品中的广泛应用提供理论支持。以脱脂花生蛋白粉（DPF）为原料,通过等电沉淀、乙醇浸提、等电沉淀与乙醇浸提相结合及碱溶酸沉技术制备花生浓缩蛋白,并分别测定其蛋白功能性（蛋白溶解性、吸水性、持油性、乳化能力及乳化稳定性、起泡能力及泡沫稳定性、凝胶性质）。结果表明：碱溶酸沉技术制备的蛋白溶解性、起泡能力及泡沫稳定性最好;而乙醇浸提制备的蛋白吸水性、持油性和凝胶性质要显著性的高于其他方法制备的蛋白产品的;不同方法制备的花生浓缩蛋白的乳化稳定性均明显低于对照（DPF）,尤以碱溶酸沉技术制备的最低。因此可知,乙醇浸提制备的蛋白适用于对吸水性、持油性和凝胶性质要求较高的食品中;碱溶酸沉技术制备的蛋白适用于对起泡能力要求较高的食品中。     

Relation between solubility and surface hydrophobicity as an indicator of modifications during preparation processes of commercial and laboratory-prepared soy protein isolates

Because water solubility is the main hydration property of proteins, solubility values of commercial and laboratory soy protein isolates, prepared under different conditions, were comparatively analyzed. In contrast, the surface hydrophobicity manifested by proteins is a physicochemical property that determines, to a great extent, the tendency of protein molecules to aggregate and so to lose solubility. On these grounds, the solubility of isolates was analyzed as a function of the surface hydrophobicity of their proteins, and, as a result, three well-defined groups of laboratory isolates were identified: (A) native, (B) partially or totally denatured with high solubility and surface hydrophobicity, and (C) totally denatured with low solubility and surface hydrophobicity. Commercial isolates could not be included in any of these groups; they were grouped as (A') partially native and (C') totally denatured. Solubility values in these two groups were similar to those of group C, but the surface hydrophobicity levels were much lower. The different processes leading to the groups mentioned above are discussed, along with the way the soy proteins are influenced by the specific preparation conditions, namely, protein concentration, chemical or thermal treatments, presence of salts, drying, and phospholipid addition, among others.     

糖接枝处理改善大豆蛋白纤维聚集体泡沫稳定性

为了探究糖接枝对大豆蛋白纤维聚集行为和泡沫性质的影响,明确蛋白质结构与功能的关系,该研究以大豆蛋白(soy protein isolation,SPI)和乳糖(lactose)为原料,通过干热法制备糖接枝大豆蛋白(SPI-lactose conjugate,SPI-Lac),以及在酸性条件下加热诱导其形成纤维聚集体(p H值2.0),制备了一种糖接枝大豆蛋白纤维聚集体(SPI-lactose conjugate fibillar aggregates),并考察了糖接枝对大豆蛋白的纤维聚集行为及泡沫性质的影响。研究结果表明:大豆蛋白在酸性条件下(p H值2.0)经加热后会发生水解,同时水解产物不断聚集形成大分子的纤维聚集体。糖接枝导致大豆蛋白的水解速度下降,但荧光光强和粒径的结果表明糖接枝能增强纤维聚集能力。SPI-Lac在中性条件下的溶解度(p H值5.0—7.0)显著高于SPI(P0.05),且不同时间处理的SPI-Lac纤维聚集体均能改善SPI在酸性条件下的溶解度(p H值2.0—5.0)。此外,不同时间处理的SPI-Lac纤维聚集体在酸性条件下的起泡能力均高于SPI纤维聚集体。SPI和SPI-Lac纤维聚集体的形成会导致SPI起泡能力的下降,但是短时间酸热处理形成的纤维聚集体泡沫稳定性得到显著改善。因此,糖接枝结合短时间酸热处理制备的糖接枝大豆蛋白纤维聚集体在中性条件下的泡沫稳定性显著提高(P0.05),是合理有效的蛋白质改性方法。     

适宜含水率保持油茶籽贮藏品质

为了确定油茶籽贮藏适宜的含水率,研究了在4℃,不同含水率(7%、10%、13%、16%、20%)油茶籽贮藏期间的品质变化。结果表明,较低的含水率能较好保持油茶籽的贮藏特性及营养品质。其中,含水率为7%的油茶籽贮藏效果较好,但与10%处理效果差异不明显(P>0.05)。在整个贮藏期,含水率为7%时油茶籽可溶性蛋白下降了13.05 mg/g,油酸含量下降了2.38%,酸值、过氧化值等品质指标上升速率较慢,同时能较好保持β-谷甾醇和角鲨烯等生物活性成分;其次是10%的含水率处理。而含水率为20%的油茶籽贮藏期间可溶性蛋白下降较快,贮藏结束时为25.47 mg/g,油茶籽劣变严重,所提取的油样品质变差,营养物质含量较少,因此含水率20%的油茶籽不适宜长期贮藏。综合考虑油茶籽品质因素和处理成本,认为控制含水率在10%以下能较好保持油茶籽的贮藏品质。该研究可为科学合理地贮藏油茶籽提供参考。     

Composition,Molecular Structure,Properties, and In Vitro Digestibility of Starches from Newly Released Canadian Pulse Cultivars

Pulse starches were isolated from different cultivars of pea, lentil, and chickpea grown in Canada under identical environmental conditions. The in vitro digestibility and physicochemical properties were investigated and the correlations between the physicochemical properties and starch digestibility were determined. Pulse starch granules were irregularly shaped, ranging from oval to round. The amylose content was 34.9–39.0%. The amount of short A chains (DP 6‐12) of chickpea starch was much higher than the other pulse starches, but the proportions of B1 and B2 chains (DP 13‐24 and DP 25‐36, respectively) were lower. The X‐ray pattern of all starches was of the C type. The relative crystallinity of lentil (26.2–28.3%) was higher than that of pea (24.4–25.5%) and chickpea starches (23.0–24.8%). The swelling factor (SF) in the temperature range 60–90°C followed the order of lentil ≈ chickpea > pea. The extent of amylose leaching (AML) at 60°C followed the order of pea ≈ chickpea > lentil. However, in the temperature range 70–90°C, AML followed the order of lentil > pea > chickpea. The gelatinization temperatures followed the order of lentil > pea > chickpea. The peak viscosity, setback, and final viscosity of pea starch were lower than those of the other starches. Lentil starch exhibited lower rapidly digestible starch (RDS) content, hydrolysis rate, and expected glycemic index (eGI). The resistant starch (RS) content of both lentil cultivars was nearly similar. However, pea and chickpea cultivars exhibited wide variations in their RS content. Digestibility of the pulse starches were significantly correlated (P < 0.05) with swelling factor (60°C), amylose leaching (60°C), gelatinization temperature, gelatinization enthalpy, relative crystallinity, and chain length distribution of amylopectin (A, B1, and B2 chains).     

Relationship of Creep-Recovery and Dynamic Oscillatory Measurements to Durum Wheat Physical Dough Properties

Durum wheat gluten strength is important in determining extrusion properties and pasta cooking quality. Durum wheats varying in strength were tested using an alveograph and a 2-g micro-mixograph, both widely accepted techniques for determination of physical dough properties. Doughs from the 2-g micro-mixograph were characterized by dynamic oscillatory and large deformation creep tests using a controlled stress rheometer. Mechanical properties obtained from both testing regimes were strongly correlated with many of the parameters provided by the alveograph and micro-mixograph. Maximum strain attained after 5 min creep ranged from <5% for the strongest least extensible cultivar to >25% for the weakest cultivar, with a coefficient of variation among replicates of <10%. Storage modulus (G′) at 2 Hz ranged from ≈7,000 Pa for the weakest cultivar to >16,000 Pa for the strongest, least extensible cultivars, with a coefficient of variation of <6%. Tan δ (G″/G′) values were ≈0.4 for the strongest versus >0.5 for the weakest cultivars, indicating the larger contribution of the elastic component in the strong cultivars. The rheometer allows discrimination of durum wheat cultivars of varying gluten strength while requiring less sample than traditional physical dough testing techniques.     

Optimization of the enzymatic deamidation of soy protein by protein-glutaminase and its effect on the functional properties of the protein

The effects of enzymatic deamidation by protein-glutaminase (PG) on the functional properties of soy protein isolate (SPI) were studied. Conditions for the deamidation were evaluated by means of response surface methodology (RSM). Optimal conditions based on achieving a high degree of deamidation (DD) with a concurrently low degree of hydrolysis (DH) were 44 °C, enzyme:substrate ratio (E/S) of 40 U/g protein and pH 7.0. Under optimal conditions, both DD and DH increased over time. SDS-PAGE results indicated that lower molecular mass subunits were produced with increasing DD. Far-UV circular dichroism spectra revealed that the α-helix structure decreased with higher DD, while the β-sheet structure increased until 15 min of deamidation (32.9% DD), but then decreased at higher DD. The solubility of deamidated SPI was enhanced under both acidic and neutral conditions. SPI with higher DD showed better emulsifying properties and greater foaming capacity than SPI, while foaming stability was decreased. It is possible to modify and potentially improve the functional properties of SPI by enzymatic deamidation using PG.     

Variations in isoflavone levels in soy foods and soy protein isolates and issues related to isoflavone databases and food labeling

The reliability of databases on the isoflavone composition of foods designed to estimate dietary intakes is contingent on the assumption that soy foods are consistent in their isoflavone content. To validate this, total and individual isoflavone compositions were determined by HPLC for two different soy protein isolates used in the commercial manufacture of soy foods over a 3-year period (n = 30/isolate) and 85 samples of 40 different brands of soy milks. Total isoflavone concentrations differed markedly between the soy protein isolates, varying by 200-300% over 3 years, whereas the protein content varied by only 3%. Total isoflavone content varied by up to 5-fold among different commercial soy milks and was not consistent between repeat purchases. Whole soybean milks had significantly higher isoflavone levels than those made from soy protein isolates (mean +/- SD, 63.6 +/- 21.9 mg/L, n = 43, vs 30.2 +/- 5.8 mg/L, n = 38, respectively, p < 0.0001), although some isolated soy protein-based milks were similar in content to "whole bean" varieties. The ratio of genistein to daidzein isoflavone forms was higher in isolated soy protein-based versus "whole bean" soy milks (2.72 +/- 0.24 vs 1.62 +/- 0.47, respectively, p < 0.0001), and the greatest variability in isoflavone content was observed among brands of whole bean soy milks. These studies illustrate large variability in the isoflavone content of isolated soy proteins used in food manufacture and in commercial soy milks and reinforce the need to accurately determine the isoflavone content of foods used in dietary intervention studies while exposing the limitations of food databases for estimating daily isoflavone intakes.     

Differences in Starch Granule Composition and Structure Influence In Vitro Enzymatic Hydrolysis of Grain Meal and Extracted Starch in Two Classes of Canadian Wheat (Triticum aestivum L.)

Starch granule composition and amylopectin structure affect starch digestibility, an important factor influencing wheat grain utilization for human food consumption. Six bread wheat cultivars with four belonging to the Canada Western Red Spring (CWRS) and two Canada Prairie Spring Red (CPSR) market classes were analyzed for the relationship between their grain constituents and in vitro enzymatic hydrolysis of starch. CPSR cultivars had higher starch and amylose concentrations compared with CWRS cultivars, which had a higher protein concentration. Starch granule size distribution did not differ among the genotypes, except AC Foremost, which had significantly (P < 0.05) higher volume percent of B‐type starch granules (≈15%) and lower volume percent of A‐type starch granules (≈9%) compared with other cultivars. Fluorophore‐assisted capillary electrophoresis revealed a lower content of R‐IV (DP 15–18, ≈6%) and a higher content of R‐VII (DP 37–45, ≈7%) chains in the CPSR cultivars compared with the CWRS cultivars. Starch in vitro enzymatic hydrolysis showed that compared with CWRS cultivars, the two CPSR cultivars had reduced amounts of readily digestible starch and higher amounts of slowly digestible starch and resistant starch. Consequently, the two CPSR cultivars also showed lower hydrolysis indexes in grain meal as well as extracted starch. CPSR cultivars, with higher starch and amylose concentrations, as well as a higher content of long chains of amylopectin, showed a reduced starch in vitro enzymatic hydrolysis rate.     

微波对大豆蛋白氧化聚集体结构及功能特性的影响

为了探究不同时间微波处理对大豆蛋白氧化聚集体的结构和功能性质的影响,由偶氮二异丁脒盐酸盐(2,2′-azobis (2-amidinopropane) dihydrochloride,AAPH)诱导构建大豆蛋白氧化反应体系,采用功率为350 W的微波对其照射不同时间(0、10、20、30、40、50、60、70 s),探究微波处理对氧化聚集大豆蛋白的结构特性和加工特性的影响。结果表明,氧化可诱导形成粒径、分子量更大,结构更致密的蛋白质聚集体,同时对加工特性造成损害。适当时间(<30 s)的微波处理会导致氧化聚集体的分子结构打开、粒径降低和浊度降低,无序结构减少,进而改善了起泡性、乳化性和持水、持油性。长处理时间(>30 s)的微波处理导致已解聚的大豆蛋白分子重新形成更大的分子聚集体,降低功能性质。这表明微波物理场可以通过改变大豆蛋白氧化聚集体的结构和聚集行为调节其功能性质,为大豆蛋白功能性质的改善及微波在大豆蛋白氧化聚集体行为调控的应用方面提供参考。     

Genetic diversity in local cultivars of garden pea (Pisum sativum L.) conserved ‘on farm’ and in historical collections

During a national Swedish collection mission of vegetable varieties conserved ‘on farm’ more than 70 pea accessions were obtained, many of which had been grown locally for more than 100 years. In spite of a likely origin in the multitude of obsolete commercial pea varieties available on the Swedish seed market in the nineteenth century, the rediscovered local cultivars have lost their original names and cultivar identity while being maintained ‘on farm’. To analyze genetic diversity in the repatriated material, 20 accessions were genotyped with twelve SSR markers and compared with 15 obsolete cultivars kept in genebanks and 13 cultivars preserved as non-viable seeds collected in 1877–1918. Most of the local cultivars were genetically distinct from each other, and in only a few cases could a possible origin in a tested obsolete cultivar be suggested. These results reflect the wide diversity of pea cultivars present in Sweden during the nineteenth century. Both between and within accession genetic diversity was larger among the historical samples of obsolete cultivars compared to local cultivars and cultivars preserved in genebanks, indicating genetic erosion over time both in genebanks and during conservation ‘on farm’. The constraints on identifying and verifying historical cultivars using genetic markers are discussed.