2013 Annual Report
1a.Objectives (from AD-416):
1. To obtain NIR spectra of soybean seeds and meals undergone different processing conditions for development of analytical technology that measures digestible energy and nutritionally available amino acids. Soybean meal samples will be ground at 20,000 rpm in water cooled, timer controlled Foss Knifetech 1095 sample mill which will be maintained between 15 and 17 deg C. Then NIR spectra will be obtained on Perstorp Analytical NIRS Systems model 6500 near infra-red spectrometer using ¼ cup transport cells and ISISCAN analytical software. System performance will be checked daily with an Infrasoft International Standard Check Cell for transports from the same company. The NIR spectra will be delivered to cooperator for development of new NIR calibrations.
2. To accurately quantify soluble oligosaccharide components of soybean meal that influence soybean feed characteristics, i.e., quantitative analysis of the major, extractable soluble oligosaccharide products (i.e. sucrose, raffinose, stachyose) from soybean meal by HPLC-RID (refractive index detection) or HPAEC-PAD (high-performance anion-exchange chromatography-pulsed amperometric detection). Will also try to use GC or GC-MS to analyze these components – it will require method development to enable simultaneous characterization and quantification of component non-reducing sugars. Suggested is GC or GC-MS of peracetylated or TMS-silylated samples, suitable for high-throughput.
3. To accurately quantify chemical composition of soluble monosaccharides (i.e. free xylose, arabinose, rhamnose, glucose, galactose, mannose, etc.) by GC or GC-MS. Requires chemical modification to prepare votile sugar derivatives suitable for GC analysis (e.g. peracetylation, alditol acetates, or aldononitrile acetate).
4. To quantify acid labile sugars by GC and/or GC/MS. Major expectation is for starch and or maltose sugars. Methodology as above applied to total sugars after acid hydrolysis, e.g. 2M TFA, 110 degrees, 30 mins.
5. To quantify acid-labile insoluble fiber/polysaccharides (presumed to be either (a) cellulosics, and/or (b) hemi-cellulosic arabinoxylans) by GC or GC/MS analysis of component Glc, Xyl, and Ara, and potentially also Gal. The cellulosic/hemicellulosic ratio is determined from the ratio of component monosaccharides.
6. To test commercial immobilized digestative enzyme assays and survey literature for in vitro assays related to soybean protein and amino acid digestability. Possible comparison study may be conducted among commercial assays and those developed in-house or from the literature.
1b.Approach (from AD-416):
This project implements the priorities of the Cooperator's Composition Improvement Effort. The strategy is addressed by supporting public soybean breeders through developing rapid near infrared reflectance (NIR) standards and methods. The laboratory work is carried out by the ARS in Peoria, IL. NIR analysis will be carried out at the lab and quantitative chemical composition of soluble monosaccharides and acid labile sugars by GC or GC-MS will be conducted at the same time. Methods will be developed to enable simultaneous characterization and quantification of component non-reducing sugars and acid-labile insoluble fiber/polysaccharides using GC or GC-MS. Other techniques such as HPLC and gravimetric analysis will also used for analyzing soluble oligosaccharide products and indigestable fiber, respectively, and compared with GC or GC-MS methods. Protein digestability of soybean and soybean meal will be tested using commercial and non-commercial assay kits.
A large number of samples were needed to cover a range of carbohydrate concentrations in order to obtain a good near infrared reflectance (NIR) correlation. In the past 10 months over 650 individual samples were prepared, the NIR spectra from two different NIRs were obtained, defatted, and % hexane extractables determined. The samples of soybeans of various cultivars grown in various locations around the United States were from the previous United Soybean Board (USB) project. The wet chemistry analysis of the defatted samples for soluble sugars has been run on just over 200 samples for soluble sugar analysis and correlated with the NIR results. A set of 20 soybean mixtures were prepared and soluble sugar analysis was performed using both wet chemistry and NIR. Of these 20, 10 mixes were chosen for three model digestibility studies and one rooster feeding study based on total soluble sugar analysis. Both the in vitro and in vivo digestibility data showed trends in the availability of certain amino acids. Cysteine and valine were shown to be the least bioavailable, while glutamic acid, arginine, and proline were the most bioavailable. The wet chemistry analysis of total insoluble carbohydrates by chromatographic analysis is underway. We are now in the process of accumulating 200 sample runs to use for the NIR correlations.