Viscoelastic Properties of a Biological Hydrogel Produced from Soybean Oil

Hydrogels formed from biopolymers or natural sources have special advantages because they may have biodegradable and biocompatible properties. The viscoelastic properties of a newly developed biological hydrogel made from epoxidized soybean oil (ESO) were investigated. The material called HPESO is a hydrolytic product of polymerized ESO (PESO). HPESO exhibited viscoelastic solid or gel behavior above 2% (wt. %) concentration at room temperature and viscous liquid behavior at 55 °C. The thermal assembly disassembly reassembly function of the HPESO hydrogel was completely reversible. The viscoelastic properties of HPESO were dependent on concentration. Analysis of modulus and concentration dependence and stress relaxation measurement indicated that HPESO was a physical gel where the cross-linkers between the molecules were physical junctions. HPESO hydrogel also exhibited fast initial recovery of its viscoelastic properties after being subjected to mechanical shear disruption. The function and behavior of the HPESO hydrogel suggest that this biomaterial may be suitable for applications in drug delivery and scaffolds of bioengineering and tissue engineering. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Structure,Protein Interactions and In Vitro Protease Accessibility of Extruded and Pressurized Full-Fat Soybean Flakes

The objectives of the present study were to determine how extrusion (barrel temperature of 100 °C) and high-pressure processing (HPP, 200 and 500 MPa, 15 min, 25 °C) of full-fat soybean flakes (FFSF) modified the structure of soybean cotyledon cells, the protein interactions and the in vitro protease accessibility. Cellular disruption of the cotyledon cells was only observed for extruded FFSF. Extrusion and HPP at 500 MPa favored formation of insoluble protein aggregates, in which oil was entrapped. High pressure size exclusion chromatography (HPSEC) and extraction methods using buffers containing SDS and 2-mercaptoethanol suggested that noncovalent interactions were the main forces in protein aggregate formation during HPP 500 MPa and extrusion. Intermolecular cross-linking by disulfide bonding was also involved in insoluble aggregates, but at a lesser extent than noncovalent interactions. Extrusion and HPP 500-MPa treatment enhanced the proteolytic attack, while treatment at 200 MPa had no impact. Drastic changes in the peptide profile of the extracted proteins were, however, only observed for the enzyme-treated 500-MPa FFSF. Optimal oil and protein extraction yields required cellular disruption of cotyledon cells and hydrolysis of protein aggregates, which were obtained with enzyme-assisted aqueous extraction of extruded FFSF.     

Effect of soybean varieties on the content and composition of isoflavone in rice-koji miso

To clarify the effect of soybean varieties on isoflavone, a useful component for human health, in soybean products, we investigated changes in the isoflavone content and composition in rice-koji miso, after fermentation/aging for 6 or 12 months using varieties of soybeans (Tohoku-126, Tohoku-135, Tohoku-139, Suzuyutaka and Chinese soybeans), by high performance liquid chromatography. In soybeans, the total isoflavone content in Tohoku-126 was 444 mg/100 g, which was 1.2–2.0 times the content in the other soybean varieties. The malonyl glycosides and aglycones in soybeans accounted for more than 60% and only a few percent, respectively. As for rice-koji miso, the total isoflavone and aglycone contents were the highest in miso prepared from Tohoku-126. The ratios of glycosides to aglycones (80.1–92.6%) in miso were higher than those in the original soybeans. The time course of the isoflavone composition during the fermentation/aging process of rice-koji miso indicated that glycosides decreased from 86.4% to 44.9% after 6 months but aglycones increased from 9.6% to 53.3%.     

Determination of soybean proteins in soybean–wheat and soybean–rice commercial products by perfusion reversed-phase high-performance liquid chromatography

The determination of additions of soybean proteins in commercial bakery products containing soybean–wheat and soybean–rice binary mixtures has been achieved in this work by high-performance liquid chromatography using a perfusive column. Soybean proteins were solubilized in a 25:75 acetonitrile–water mixture containing 0.3% (v/v) acetic acid by ultrasonication for 10 min and centrifugation for 5 min. Soybean proteins were separated from rice and wheat proteins in less than 4 min using a linear binary gradient of acetonitrile–water containing 0.3% (v/v) acetic acid as ion-pairing agent. The proposed method was proved to be specific and sensitive making possible the detection and the quantitation of additions of about 0.10% (w/w) and 0.33% (w/w), respectively, of soybean proteins in soybean–wheat and soybean–rice products (related to 1 g of initial product). Precision and recoveries observed were also acceptable. The method was applied to the determination of soybean proteins in different commercial bakery products.     

Coriander (<Emphasis Type="Italic">Coriandrum sativum</Emphasis> L.) seed oil improves plasma lipid profile in rats fed a diet containing cholesterol

Coriander (Coriandrum sativum L.) seed oil (COR) is a promising oil with high levels of bioactive compounds. Very little information, however, is available on the effect of administration of COR on different aspects of plasma lipid profile in experimental animals. In view of the important implications, the effect of administration of COR and oil blend [a mixture of soybean oil, coriander oil and sunflower oil (4:2:4, w/w/w; Blend)] on the profile of plasma lipids was investigated in 24 male albino rats placed on a cholesterol-rich (1%) basal diet as compared to rats on a cholesterol-free basal diet. Coriander seed oil and Blend were analyzed for composition of fatty acid, sterol and tocopherol. The levels of bioactive compounds (sterols and tocopherols) were higher in COR than in the Blend. In addition, the antiradical potential of COR and Blend was measured and the results showed that COR had stronger radical scavenging activity than Blend. In the biological experiment, rats were divided into four diet groups. The negative control group (control) consumed the basal diet (BD) only, which contained wheat starch, casein and cellulose, as well as mineral and vitamin mixtures. To the BD were added 1 g/100 g cholesterol (Chol/group), or both (Chol/COR group) and (Chol/Blend group). The groups did not differ before the experiment, which lasted 60 days. Plasma total lipids (TL), triacylglycerols (TAG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein-cholesterol (HDL-C) were measured at day 15, 30, 45 and 60 during the experiment period. Generally, COR and Blend-supplemented diets decreased the levels of TL, TC, TAG and LDL-C in plasma. In addition, significant increase in the levels of HDL-C was observed for Chol/COR and Chol/Blend groups. The results demonstrated that COR, and to a relatively lesser degree Blend, have hypocholesterolemic properties in rats fed a cholesterol-rich diet.     

Determination of soybean proteins in commercial heat-processed meat products prepared with chicken,beef or complex mixtures of meats from different species

The addition of foreign proteins (mainly soybean proteins and milk proteins) to heat-processed meat products is a common practice. This work approaches the determination of additions of soybean proteins in heat-processed meat products prepared with chicken meat, beef meat, and complex mixtures of meats from different species (chicken, pork, beef, and turkey) by perfusion reversed-phase high-performance liquid chromatography. The applied method was previously developed for the determination of soybean proteins in pork and turkey meat products but it has never been tested for the determination of soybean proteins in other heat-processed meat products containing other kinds of meats. This paper demonstrates the validity of this method for the detection of soybean proteins in heat-processed meat products containing different varieties of meats and even in the presence of other foreign proteins such as milk proteins. The specificity and existence of matrix interferences have been checked for these samples and accuracy has been evaluated by the comparison of the soybean protein contents determined by the proposed method and the official ELISA method.     

酶工程技术在开发活性多肽方面的研究进展

概述了酶工程技术在开发生物活性肽方面的研究进展,着重介绍了利用酶工程技术生产大豆多肽、玉米肽、酪蛋白磷酸肽等方面的研究现状。     

大豆色拉油抗结晶能力研究

采用NMR法对由美国、巴西进口大豆加工的大豆色拉油抗结晶能力进行测评,并讨论大豆种类和大豆油 精炼条件对大豆色拉油抗结晶能力的影响。结果表明,大豆种类对大豆色拉油的抗结晶能力影响很大,而目前精炼 产生的脂肪酸异构反应对大豆色拉油抗结晶能力影响不大。     

酶工程技术在开发活性多肽方面的研究进展

概述了酶工程技术在开发生物活性肽方面的研究进展，着重介绍了利用酶工程技术生产大豆多肽、玉米肽、酪蛋白磷酸肽等方面的研究现状。