Progress 09/01/02 to 08/31/04
Outputs
We updated our strategic plan to capitalize on the industrial enzyme library of our partner Genencor International to add value to soy protein products. Our analysis indicates that we should refocus on enzyme-assisted aqueous processing (EAAP) to replace hexane to extract oil. EAAP integrates better into a biorefinery concept than hexane extraction. Genencor delivered four new enzymes to be screened. These enzymes were mainly carbohydrases believed to alter the carbohydrate matrix of the soybean to facilitate protein and oil separation. We hydrolyzed soy flour using Genencor Protease 899 and evaluated the hydrolysate in high-performance melamine-urea-formaldehyde resins for wood adhesives. Soy flour was hydrolyzed with no difficulty and maximum solids content and viscosity achieved were equivalent to those produced using more expensive high-pressure alkali hydrolysis (HPAH). The adhesives prepared with enzyme-hydrolyzed soy flour worked well in the adhesive formula and
boards bonded with the adhesives had equivalent strength, water resistance and formaldehyde emission properties as did boards bonded with adhesives formulated with the HPAH hydrolysate. Enzymes can be used to prepare an excellent product in manufacturing soy protein-based adhesives. The yield of soy protein isolate (SPI) is limited by incomplete extraction. Six carbohydrases were evaluated for their impact on protein extraction yield, reducing sugars and peptide profile. Multifect pectinase increased protein yield by almost 50% and reducing sugars by 10-fold. All other enzymes increased protein extraction yield <10%. Peptide profiles were not affected. Multifect pectinase increased protein extraction but significant amounts were lost to the whey during SPI precipitation. The peptides retained their glycosides, thus, the products and functionalities resulted from proteolytic activity. We developed an ELISA method to evaluate the native state of soy protein. We screened the abilities of
one cellulase, two endoproteases, and three exoproteases to improve functional properties of soy flour. Multifect Neutral gave the most interesting changes to the properties of soy flour. Multifect Neutral and Exoprotease C were used to hydrolyze four soy protein products (hexane-extracted soy flour, extruded-expelled partially defatted soy flour, ethanol-washed soy concentrate (SPC) and SPI) to 2 and 4% degree of hydrolysis (DH) and compared to bromelain hydrolysates, a widely used endoprotease in the food industry. Protein solubilities of all substrates increased as DH increased when using Multifect Neutral. Emulsification capacity and hydrophobicities of the enzyme-modified flours decreased after hydrolysis, whereas these values increased for SPC and SPI. Hydrolyzed SPC had lower foaming capacity and stability. Hydrolysis significantly decreased viscosity. The peptide profile of flours having high proportions of native-state proteins changes little due to hydrolysis compared to SPC
and SPI.
Impacts
Performance of soy protein in food and adhesive applications was improved and protein extraction efficiency was modestly improved. These advances will lead to new, lower-cost products allowing more soy protein to be used in food, which has been shown to have health benefits. Using hydrolyzed soy protein in traditional wood adhesive reduces worker and consumer exposure to carcinogenic formaldehyde.
Publications
- Jung, S., D. Rickert, N. Deak, E. Aldin, J. Recknor, L.A. Johnson, and P.A. Murphy. 2003. Comparison of Kjeldahl and Dumas Methods for Protein Content Determination in Soy Products. J. Am. Oil Chem. Soc. 80:1169-1173.
- Rickert, D.A., L.A. Johnson, P.A. Murphy. 2004. Improved Fractionation of Glycinin and β-Conglycinin and Partitioning of Phytochemicals. J. Agric. Food Chem. 52:1726-1734.
- Rickert, D.A., Johnson, L.A., Murphy, P.A. 2004. Functional Properties of Improved Glycinin and β-Conglycinin Fractions. J. Food Sci. 69:303-311.
- Jung, S., D. Rickert, N. Deak, E. Aldin, J. Recknor, L.A. Johnson, and P.A. Murphy. 2004. Comparison of Kjeldahl and Dumas Methods for Protein Content Determination in Soy Products for ISS and Planetary Outpost Missions, NASA Food Technology Commercial Space Center Symposium, Ames, IA. April 21. Abstract #FP02, p 62-63.
- Jung, S., P. Murphy, and L.A. Johnson. 2003. Pectinases and Proteases: Effects on Protein and Functional Properties of Soy Protein Ingredients. 2003 IFT Annual Meeting and Food Exposition, Chicago, IL. July 12-16. Program Book, Abstract 11-5, p.13.
- Jung, S. and L.A. Johnson. 2003. Functional Properties of Soy Protein Modified by an Endopeptidase at Low Degrees of Hydrolysis. 2003 Annual Meeting of American Association of Cereal Chemists, Portland, OR. Sept. 28-Oct. 2. Program Book, Abstract 25. p.70.
- Myers, D.J. and K. Dias. 2004. Use of Enzymes to Produce a Protein Hydrolyzate to Use in Wood Adhesive Formulation. US Provisional Patent No.60/569,562.
- Dias, K., D. Myers, Y. Bian and D. White 2004. Soy Protein Hydrolyzate as an Ingredient in Soy Adhesive Formulation. 2004 Annual Meeting and Exposition of the American oil Chemists Society, Cincinnati, OH. May 9-12. 2004 Annual Meeting Abstracts, p.122.
|
Progress 01/01/03 to 12/31/03
Outputs
We continue to keep current the strategic plan developed in the previous one-year project to capitalize on the extensive industrial enzyme library of Genencor International, Inc., to add value to soybean protein products. Our analysis indicates that we should shift the project's future focus towards aqueous extraction to replace hexane with water using enzymes to enhance extraction. Aqueous processing can better integrate into a soybean biorefinery concept than traditional hexane extraction. We evaluated different reaction times (15, 30, 60, 90 and 120 min) using 50 microliters/g enzyme to substrate and tested the hydrolysates in high-performance melamine urea formaldehyde (MUF) resins. We tested various performance properties, such as gel time, water resistance and viscosity, of the adhesives. There were no significant differences in any of the test performance properties of the adhesives made with the hydrolysates produced with different reaction times. These
observations must be verified in test boards to be certain no loss in bond strength or water resistance occurs. Short reaction times and replacing alkaline hydrolysis with a more environmentally friendly enzyme process are important to achieve competitive costs. We continued to screen Genencor enzymes for their abilities to restore functional properties of soy flour using one cellulase, two endoproteases (Multifect Neutral and Multifect P3000), and three exoproteases (Exopeptidase A, Exopeptidase B, Exopeptidase C). The cellulase increased the solubility from 70 to 75%, without modifying the protein profile or emulsification capacity (EC). EC decreased with extent of hydrolysis. This observation confirmed the previous results obtained during year 1. Changes in functional characteristics of four soy protein products (hexane-extracted soy flour, extruded-expelled partially defatted soy flour (EE), ethanol-washed soy concentrate and soy protein isolate) modified by an endoprotease
(Multifect Neutral) and an exoprotease (Exopeptidase C) at low degrees of hydrolysis were substrate-dependent. The emulsification capacities of soy flours decreased with hydrolysis, but increased in soy concentrate and soy isolate. This observation was confirmed by microscopy analysis of dispersed droplets and measuring surface hydrophobicity. The yield of soy protein isolate is limited by incomplete extraction. Six new carbohydrases and pectinases and combinations of these enzymes were evaluated for their abilities to increase protein extractability. The yield of protein was increased by almost 10% and there was no modification of the protein profile of the extracted protein except for the two pectinases. The protein isolate made with a pectinase-modified extract had improved solubility at pH 4 and foaming stability. An enzyme-linked immunosorbent assay (ELISA) was developed to characterize native state of beta-conglycinin and glycinin, and will enhance our ability to characterize
enzyme-modified proteins.
Impacts
This project should lead to improved performance properties in food and adhesive applications as well as improved extraction efficiency in processing soybeans into value-added protein ingredients. These advances will lead to new, lower cost soy protein products and allow food processors to use more soy protein, which has been shown to have significant health benefits.
Publications
- Jung, S., D. Rickert, N. Deak, E. Aldin, J. Recknor, L.A. Johnson, and P.A. Murphy. 2003. Comparison of Kjeldahl and Dumas Methods for Protein Content Determination in Soy Products. J. Am. Oil Chem. Soc. 80(12):1169-1173.
|
Progress 01/01/02 to 12/31/02
Outputs
We updated the strategic plan developed in the previous one-year project to capitalize on the extensive industrial enzyme library of Genencor International, Inc., to add value to soybean protein products. Market research identified bitter taste as a limitation for enzyme modification technologies. Future efforts should focus on this issue where there are food applications. Because soy flour is less expensive than protein isolate ($0.20 vs 1.00/lb), this year's project focuses on using soy flour instead of soy protein isolate unlike all previous work. For wood adhesives, protein solutions must have low viscosity at high solids levels to facilitate spray application. Soy flour was hydrolyzed with no difficulty using Genencor Protease (GP 899) reducing viscosity, despite containing significantly less protein (52% for soy flour vs 90% for protein isolate). At 30% solids, the enzyme hydrolyzed soy flour had similar viscosity to 26-32% alkali hydrolyzed soy flour. Use of 50
ul/g enzyme achieved the best bond performance in test boards. Boards bonded with adhesives formulated with the enzyme-hydrolyzed soy flour had comparable strength, water resistance and formaldehyde emission properties compared to boards bonded with adhesives formulated with alkali-hydrolyzed soy flour. Soy protein is usually denatured during oil extraction or isolation losing solubility and other functional properties but enzyme modification may restore or improve these properties in foods and industrial products. Five to eight new enzyme preparations under development by Genencor are being evaluated for their potential to improve functional properties of soy flour. Two endoproteases (Multifect P3000 and Multifect Neutral) increased protein solubility at pH 7 from 75 to 85%; and one cellulase (IndiAge Super L) increased solubility from 70 to 75%. Both proteases reduced emulsification capacity as was observed before. At low hydrolysis, enthalpy of denaturation and the native
electrophoretic pattern was retained indicating preservation of some native functionality. All functionalities of the cellulase-treated soy flour except for solubility were unaffected by the enzyme treatment. The yield of soy protein isolate is limited by incomplete extraction. Pectinase was examined to determine if it could increase the extraction yield from soy flakes. Both 5 and 10% enzyme concentrations increased protein yield by 50% compared to the control and reducing sugars by 10-fold. A protein isolate made with this enzyme-treated extract had increased solubility at pH 7 and 4 by 20 and 60%, respectively. Emulsification capacity increased by 10% and foaming parameters increased by 10 to 50%. SDS-PAGE profiles showed modifications of the b-conglycinin and appearance of new peptides, which could result from deglycosylating this protein.
Impacts
This project should lead to improved performance properties in food and adhesive applications as well as improved extraction efficiency in processing soybeans into value-added protein ingredients. These advances will lead to new, lower cost soy protein products and allow food processors to use more soy protein, which has been shown to have health benefits.
Publications
- No publications reported this period
|
|