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United States Department of Agriculture

Agricultural Research Service

Research Project: Optimization of the Nutritional, Functional, and Sensory Properties of Raw and Processed Legumes, Grains, and Specialty Crops

Location: Healthy Processed Foods Research

Title: Physicochemical, nutritional and infrared spectroscopy evaluation of an optimized soybean/corn flour extrudate

Authors
item Guzman-Ortiz, Fabiola -
item Berrios, Jose
item Hernández-Sánchez, H. -
item Yee-Madeira, H. -
item San Martín-Martínez, E. -
item Robles-Ramírez, Carmen -
item Rojas-López, Marlon -
item Mora-Escobedo, Rosalva -

Submitted to: Journal of Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 15, 2014
Publication Date: N/A

Interpretive Summary: The use of the statistical tool central composite design, using a response methodology, successfully described the effect of the independent extrusion processing variables of feed moisture, die temperature and soybean proportion on specific parameters of product quality, such as expansion index, water absorption index, water solubility index and total color difference. The statistical tool used in the study, allowed to obtain the best processing conditions at 25.8% feed moisture, 160°C die temperature and 58%/42% soybean/corn proportion. The generation of low molecular weight polypeptides, determined in the extruded product, was associated to an increased in in vitro protein digestibility (IVPD). Changes in the protein structure was studied using and Infrared spectroscopy technique. The changes in the protein structures were associated to the increased in IVPD in the extruded sample. This study provides an insight on the relationship between the protein structure and digestibility.

Technical Abstract: A central composite design using RMS successfully described the effect of independent variables (feed moisture, die temperature and soybean proportion) on the specific parameters of product quality (expansion index, water absorption index, water solubility index and total color difference) studied. The optimized processing conditions were obtained with 25.8% feed moisture, 160°C die temperature and 58%/42% soybean/corn proportion. The generation of low molecular weight polypeptides was associated to an increased in in vitro protein digestibility (IVPD) of the extrudate. The FTIR spectra of the soybean/corn mix before and after extrusion showed that the a¬helix structure remained unchanged after extrusion. The band associated with ߬sheet structure showed to be split into two bands at 1624 and 1640 cm-1.These changes in the ߬sheet structures may be also associated to the increased in IVPD in the extruded sample. This study provides an insight on the relationship between the protein structure and digestibility.

Last Modified: 12/19/2014
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