The effects of two commercial endoproteases (Protex 6L and Protex 7L, Genencor Division of Danisco, Rochester, NY, USA) on the oil and protein extraction yields from extruded soybean flakes during enzyme-assisted aqueous extraction processing (EAEP) were evaluated. Oil and protein were distributed in three fractions generated by the EAEP: cream + free oil, skim and insolubles. Protex 6L was more effective for extracting free oil, protein and total solids than Protex 7L. Oil and protein extraction yields of 96 and 85%, respectively, were obtained using 0.5% Protex 6L. Enzymatic and pH treatments were evaluated to de-emulsify the oil-rich cream. Cream de-emulsification generated three fractions: free oil, an intermediate residual cream layer and an oil-lean second skim. Total cream de-emulsification was obtained when using 2.5% Protex 6L and pH 4.5. The extrusion treatment was particularly important for reducing trypsin inhibitor activity (TIA) in the protein-rich skim fraction. TIA reductions of 69 and 45% were obtained for EAEP skim (the predominant protein fraction) from extruded flakes and ground flakes, respectively. Protex 6L gave higher degrees of protein hydrolysis (most of the polypeptides being between 1,000 and 10,000 Da) than Protex 7L. Raffinose was not detected in the skim, while stachyose was eliminated by a-galactosidase treatment.

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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.

The effect of isoflavone on soy milk and tofu astringency was investigated, and no consistency was found between an undesirable astringent taste and isoflavone contents. Isoflavone-enriched extract (approximately 39% isoflavones) showed no astringency. Soybean foods having high amounts of isoflavones showed less astringency. About 80% of isoflavones exist freely in both soy milk and tofu, but 55% of phytates (which play an important role in the formation of the tofu curd network) exist freely in the soy milk, and 6-13%, on the basis of coagulation, existed freely in the tofu curds. A 1% potassium phytate solution at pH 7 showed the very same astringency as soy milk; however, calcium phytate at the same concentration and pH showed no undesirable sensation. Thus, it is assumed that the astringent characteristics caused by phytic ions in soy milk are lost upon conversion of phytic ions to their insoluble salt forms during soy milk coagulation.

Salmonella enteritidis is one of the leading bacterial causative agents of acute human gastroenteritis from poultry. The objective of this study was to determine the efficacy of the patent pending low pKa, lipid-based natural R2 product of Feed Energy on commercial layer pullets using a Salmonella enteritidis challenge model. One-day-old HyLine W-36 layer pullets were placed in two separate rooms (116 sq.ft.) at 48 birds per pen. At 10 weeks of age, pullets were placed in individual cages of an A-Frame layer cage with a plastic wall between the R2 treatments (48 cages) and 48 cages for the challenge control. All birds were orally gavaged S.E. at 17 weeks with 5.2x108 CFU/bird. The dietary treatments from day 1: Control: Basal Diet + Distiller corn Oil (DCO), Treatment: Basal Diet + R2 product. The birds were fed a starter feed from day 1 to 12 weeks of age with 2.5% added fat and grower diet from 12 to 20 weeks with 1% added fat. Salmonella prevalences in ceca, ovaries, and cloacal swabs were compared between treatments and weeks using logistic regression. Salmonella CFUs in culture-positive samples were compared using linear regression. All statistical testing assumed a two-sided alternative hypothesis, and P < 0.05 was considered significant. Ceca and ovary samples were evaluated from one-half of the birds at 1 week and 3 weeks post challenge. At both sample times, the birds fed the R2 product had numerically less S.E. prevalence in ceca, ovaries, and cloacal swabs. Although there was not a statistical difference for each individual tissue tested, there was an obvious trend in reduction over time that would indicate the R2 product may be helping hens to more rapidly clear S.E. colonization and long-term benefits in preventing and/or reducing S.E. colonization of the ceca and ovaries.