Antigenicity in soybean hypocotyls and its reduction by twin-screw extrusion

The characterization of soybean germ oil and the antioxidative activity of its phytosterols

The aim of this study was to characterize the composition of soybean germ and its oil from Northeast (NE-SG) and Shandong Province (SD-SG) of China with a focus on the composition of fatty acids and phytosterols as well as physicochemical properties. The results show that the average contents of water, protein, crude fat, crude fiber and ash of NE-SG and SD-SG were 8.23 ± 0.11%, 40.47 ± 0.10%, 11.65 ± 0.14%, 6.20 ± 0.09% and 4.79 ± 0.14%, respectively. The major fatty acids of the two soybean germ oils were linoleic acid (NE-SGO, 55.45%; SD-SGO, 52.15%), alpha-linolenic acid (NE-SGO, 16.21%; SD-SGO, 18.50%), palmitic acid (NE-SGO, 12.59%; SD-SGO, 11.40%) and oleic acid (NE-SGO, 9.87%; SD-SGO, 10.96%). The soybean germs were rich in phytosterols (NE-SGO, 3168 mg/100 g oil; SD-SGO, 3010 mg/100 g oil) consisting of β-sitosterol, Δ7-stigmastenol, campesterol, stigmastanol, and citrostadienol. The antioxidant ability of soybean germ phytosterols was evaluated using DPPH˙ and OH˙ radical scavenging assays, β-carotene protection assay and a heating oil system. The results demonstrated that soybean germ phytosterols had better antioxidant ability in oil systems than in non-oil systems. The antioxidant ability of these phytosterols was temperature- and time-dependent since it was more effective at lower temperatures (60 °C) with longer times as compared to higher temperatures (120 °C and 180 °C) with shorter times. These results prove that soybean germ phytosterols could be used as antioxidants in preventing lipid oxidation in foods stored at a low temperature for a long time.

Soybean germ oil reduces blood cholesterol by inhibiting cholesterol absorption and enhancing bile acid excretion

Soybean germ oil is beneficial in management of hypercholesterolemia in hamsters fed a high cholesterol diet.

Characterization of physicochemical properties and IgE-binding of soybean proteins derived from the HHP-treated seeds

The aim of this work was to evaluate the characterization of physicochemical properties and IgE-binding of soybean proteins derived from the high hydrostatic pressure (HHP) treated seeds. Soybean seeds were treated by HHP at different pressures, and changes in the physicochemical properties of soybean proteins were characterized by proteins solubility, free sulfhydryl (SH) content, surface hydrophobicity, and secondary structures. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme-linked immunoabsorbent assay (ELISA) were used to define the proteins patterns and IgE-binding ability. The results showed that HHP treatment in the ranges of 0 to 500 MPa led to a slight but gradual decline in free SH content. The solubility and hydrophobicity of soybean proteins increased sharply from 100 to 200 MPa, and gradually decreased upon the further increase of pressure. The α-helix and β-sheets contents of soybean proteins decreased, while the random coil content increased. The SDS-PAGE showed that HHP treatment of 100 to 200 MPa could dissociate the proteins, breaking the aggregates into smaller units, while the treatment ranging from 300 to 500 MPa could induce the proteins aggregation into larger units. Moreover, the ELISA revealed that the IgE-binding of soybean proteins after HHP treatment at 200 MPa decreased 61.7% compared to the untreated group. Our findings suggested that HHP processing could not only modify the physicochemical properties of soybean proteins, but also significantly reduce its IgE-binding at an appropriate pressure level.

Advances of research on glycinin and β-conglycinin: a review of two major soybean allergenic proteins

Being an important crop, soybean is widely used in the world and plays a vital role in human and animal nutrition. However, it contains several antinutritional factors (ANFs) including soybean agglutinin, soybean protease inhibitors, soybean allergenic proteins, etc., that may result in poor food utilization, decreased growth performance, and even disease. Among these ANFs, soybean allergenic proteins can lead to allergic reactions in human and animals, which has become a public problem all over the world, but our knowledge on it is still inadequate. This paper aims to provide an update on the characteristics, detection or exploration methods, and in vivo research models of soybean allergenic proteins; especially glycinin and β-conglycinin are deeply discussed. Through this review, we may have a better understanding on the advances of research on these two soybean allergenic proteins. Besides, the ingredient processing used to reduce the allergenicity of soybean is also reviewed.

Soy germ protein concentrate diet decreased body fat weight and increased hindlimb muscle weight in rats

The purpose of this study was to investigate the effects of soy germ protein intake on body composition. Wistar rats were fed experimental diets for 16 weeks. These consisted of soy germ protein, soy protein, or casein. Abdominal adipose tissue weights significantly lower and hindlimb muscle weights were significantly higher in the soy germ protein group than in the casein group.

Effects of extrusion conditions on trypsin inhibitor activity of full fat soybeans and subsequent effects on their nutritional value for young broilers

1. Increasing proportions of soybeans in poultry diets have highlighted the importance of correct processing to inactivate the anti-nutritional factors present whilst maintaining protein quality. 2. Ground full fat soybeans (FFSB) were extruded using a Clextral laboratory model twin-screw extruder with 0.75 l/h of water and end barrel temperatures of 90, 110, 130 and 160 degrees C resulting in trypsin inhibitor activities (TIA) of 14.8, 9.6, 4.5 and 1.9 mg/g sample. 3. The 4 extrudates were used at three different inclusion levels: 200, 400 and 600 g/kg semi-synthetic diet and fed to male Ross broiler chicks from d 19 to d 26. Digesta samples were taken for measurement of coefficient of ileal apparent amino acid digestibility (CIAD) and both pancreas and whole bird weights were measured. 4. Concentration of ileal apparent digestible lysine was increased from 10.53 to 17.63 g/kg FFSB by increasing extrusion temperature from 90 to 160 degrees C. CIAD of lysine was also improved from 0.58 to 0.86. Other amino acids showed similar improvements in both their ileal apparent digestible concentration and CIAD. 5. Mean weight gain over 3 d increased linearly from 42 to 95 g per bird with increasing extrusion temperatures of FFSB. Pancreatic enlargement was evident after 6 d of feeding with FFSB processed at lower temperatures, even when the TIA level was at the recommended threshold of 4 mg/g. 6. The results emphasise the importance of controlled conditions during processing of FFSB for poultry diets and suggest that processing of FFSB in order to reduce TIA levels below 4 mg/g may provide significant benefits for broiler chicks.

Immunoassays of soy proteins

Proteins of soybeans (Glycine max) are widely used in animal and human nutrition. In addition to the bulk of the seed storage proteins, which are classified as albumins and globulins, approximately 6% of soybean proteins are classified as inhibitors of trypsin and chymotrypsin and approximately 0.5% are sugar-binding lectins. The two major classes of inhibitors are the Kunitz trypsin inhibitor, which inhibits trypsin, and the Bowman-Birk inhibitor (BBI), which inhibits both trypsin and chymotrypsin. Unless removed or inactivated, these inhibitors and lectins can impair the nutritional quality and safety of soy-based diets. On the other hand, several studies suggest that BBI can also function as an anticarcinogen, possibly through interaction with a cellular serine protease. Good-quality soybean proteins contribute to the nutritional value of many specialty foods including infant soy formulas and milk replacers for calves, and provide texture to many processed foods. However, they may also induce occasional allergic responses in humans. This paper outlines immunoassays developed to analyze for soy proteins in different soybean lines, in processed foods, and in nonsoy foods fortified with soy proteins. An assessment of the current status of immunoassays, especially of enzyme-linked immunosorbent assays for soybean inhibitors of digestive enzymes, soy globulins, and soy lectins, demonstrates the usefulness of these methods in plant and food sciences and in medicine.

Transfer of soy isoflavone into the egg yolk of chickens

A diet containing a high concentration of soy isoflavone was administered to laying hens and the contents of the isoflavones transferred to the plasma and egg yolk were measured. A method for quantitatively measuring the concentration of isoflavone in the yolk was first established, before a high concentration of soy isoflavone was administered to the laying hens over an 18-day period. The concentrations of isoflavone in the plasma and egg yolk reached their highest on the 12th day of the feeding period, the values being 3,167 nmol/l and 65.29 microg/100 g, respectively. The concentration of cholesterol in the yolk was slightly affected during the early stages of the feeding period. These findings clearly demonstrate that soy isoflavone was transferred into the yolk from the feed and that the cholesterol concentration in the yolk was affected by administering the soy isoflavone-enriched feed.