Characterizing the Structural and Functional Properties of Soybean Protein Extracted from Full-Fat Soybean Flakes after Low-Temperature Dry Extrusion.

Wenjun Ma,Shuang Zhang,Yang Li,Fengying Xie,Yufan Sun,Huan Wang,Baokun Qi,Miao Hu,Mingming Zhong,Jianyu Zhu

doi:10.3390/molecules23123265

Wenjun Ma, Shuang Zhang + Show 8 more

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https://doi.org/10.3390/molecules23123265

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Abstract

The soy protein isolates (SPI) extracted from different extruded full-fat soybean flakes (FFSF), and their conformational and functional properties were characterized. Overall, the free thiol (SH) content of SPI increased when the extrusion temperature was below 80 °C and decreased at higher temperatures. Soy glycinin (11S) showed higher stability than β-conglycinin (7S) during extrusion. Results also indicated that the increase in some hydrophobic groups was due to the movement of hydrophobic groups from the interior to the surface of the SPI molecules at extrusion temperatures from 60 to 80 °C. However, the aggregation of SPI molecules occurred at extrusion temperatures of 90 and 100 °C, with decreasing levels of hydrophobic groups. The extrusion temperature negatively affected the emulsifying activity index (EAI); on the other side, it positively affected the emulsifying stability index (ESI), compared to unextruded SPI.

Highlights

Soybean ( Glycine max (L.) Merrill) is an exceptional legume because of its extraordinary of oil and protein contents
The Molecular Weight (MW) of soy protein isolates (SPI) samples changed as the extrusion temperature increased
The untreated SPI sample had a peak in the MW which matched β-conglycinin

Summary

Introduction

Soybean ( Glycine max (L.) Merrill) is an exceptional legume because of its extraordinary of oil and protein contents. Soybean oil is mainly extracted by solvent extraction, which denatures the protein during the process but affects the quality of the oil too [1,2]. The search for an efficient means of pretreatment that achieves both cell distortion and low denaturation of soybean protein before enzymatic extraction is significant to oil extraction and protein using EAEP. Pretreatments such as high pressure, ultrasound, and extrusion have been extensively studied [6,7,8].

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