Kirby D. Hayes

The effects of processing and extraction conditions on content, profile, and stability of isoflavones in a soymilk system.

The effect of processing temperature and pH as well as enzyme-assisted extraction on the content and profile of isoflavones in a soymilk system was investigated. Isoflavone content in thermally treated soymilk at pH 7 and pH 9 was determined following a standard solvent extraction or an enzyme-assisted extraction protocol. Upon thermal processing, at both pH 7 and pH 9, significant interconversions were noted, indicated by the observed decrease in malonylglucosides with the concurrent increase in beta-glucosides. Enzyme-assisted extraction resulted in enhanced isoflavone extraction efficiency and revealed significant loss in total isoflavone content upon processing. This observation suggested that protein-isoflavone interactions, which are dependent on the protein structure and isoflavone form, affect isoflavone extractability, leading to underestimation of any loss that might have occurred in previously reported thermal studies. Accurate isoflavone measurements are essential to determine the processing conditions that result in the least loss of the biologically relevant isoflavone content.

Measurement of plasminogen concentration and differentiation of plasmin and plasminogen using Fourier-transform infrared spectroscopy

Abstract Methods using Fourier-transform infrared (FT-IR) spectroscopy in combination with multivariate statistical analysis were developed to determine the plasminogen concentration in various protein solutions and to differentiate between plasmin and plasminogen. FT-IR spectra of plasminogen and plasmin in water and solutions containing sodium caseinate, whey protein concentrate, and a mixture of β -lactoglobulin and sodium caseinate were obtained using attenuated total reflectance (ATR) FT-IR. Discriminant analysis and partial least-squares analysis were used to analyze data. Standard curves to determine plasminogen and plasmin concentrations in water and protein solutions were constructed successfully using PLS ( R 2 >0.9). FT-IR combined with discriminant analysis was also able to differentiate between plasminogen and plasmin. Developed methods will allow further study of the factors that influence plasminogen and plasmin in the presence of casein and whey proteins.

FTIR determination of ligand-induced secondary and tertiary structural changes in bovine plasminogen

Human plasminogen undergoes a large tertiary structural change in the presence of lysine derivatives (e.g. epsilon-amino caproic acid, EACA). This change facilitates human plasminogen activation by human plasminogen activators, resulting in elevated blood plasmin levels. It is hypothesized that this structure-function relationship is similar for bovine plasminogen. The objectives of this study were to investigate the effect of the ligand EACA on the secondary structure of plasminogen (bovine, human, and rabbit) and the tertiary structure of bovine plasminogen using Fourier-transform infrared spectroscopy (FTIR). Spectra of plasminogen, EACA, and a mixture of plasminogen and EACA in water and deuterium were collected using FTIR. Fourier-self deconvoluted spectra in the amide I region (1700-1600 cm(-1)) were used to detect changes in secondary structure of plasminogen after EACA addition. Change in bovine plasminogen tertiary structure was determined by comparing ratios of amide II (1600-1500 cm(-1)) to amide I bond intensities over time for samples in deuterium. No differences in secondary structure were observed for any plasminogen in the presence of EACA; however, addition of EACA significantly changed tertiary structure of bovine plasminogen. This tertiary structural change indicates a transition from a folded to an unfolded state, which could be more easily converted to plasmin. These results are consistent with reported human plasminogen studies using neutron scattering (tertiary structure) and circular dichroism (secondary structure) methods.

Equivalent system mass of producing yeast and flat breads from wheat berries, A comparison of mill type

Wheat is a candidate crop for the Advanced Life Support (ALS) system, and cereal grains and their products will be included on long-term space missions beyond low earth orbit. While the exact supply scenario has yet to be determined, some type of post-processing of these grains must occur if they are shipped as bulk ingredients or grown on site for use in foods. Understanding the requirements for processing grains in space is essential for incorporating the process into the ALS food system. The ESM metric developed by NASA describes and compares individual system impact on a closed system in terms of a single parameter, mass. The objective of this study was to compare the impact of grain mill type on the ESM of producing yeast and flat breads. Hard red spring wheat berries were ground using a Brabender Quadrumat Jr. or the Kitchen-Aid grain mill attachment (both are proposed post-harvest technologies for the ALS system) to produce white and whole wheat flour, respectively. Yeast bread was made using three methods (hand+oven, bread machine, mixer with dough hook attachment + oven). Flat bread was made using four methods (hand+oven, hand+griddle, mixer+oven, mixer+griddle). Data on all inputs (active time, passive time, mass and volume of ingredients and equipment, power) were measured and used to calculate ESM. Assumptions were based on data in NASA documents. Data were analyzed using PC-SAS with significance at P < 0.05. Grain mill type significantly (P < 0.05) influenced the ESM of making both bread types; and the Brabender Quadrumat Jr. contributed significantly (P < 0.05) more mass than the Kitchen-Aid grain mill to the ESM for producing both types of bread. Results can be used by systems analysts to define energy and volume requirements for the food system and by researchers to select and modify food production scenarios.