Critical evaluation of the functionality of soy protein isolates obtained from different raw materials
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The objectives of the present study were to assess how structural and gelation properties of soy protein isolates (SPIs) are affected by the characteristics of the soybean meal starting material used for protein extraction. The different degree of denaturation and aggregation due to processing treatments undergone by the soybean meals significantly affect the soy protein structural organization and functional properties. The main type of interaction responsible for the aggregates differed in the commercial and laboratory isolates, thus impacting on the protein composition of the soluble fraction of the different isolates. Spectroscopy analysis revealed that the commercial SPIs differ from the lab samples essentially due to the degree of protein aggregation and to differences in the tertiary structure (amide II). At the structural level, the lab-prepared SPIs obtained from the raw soy meal subjected to more extensive processing treatments is the one closest to the commercial samples, differentiating itself from the other laboratory isolates by the aggregation state. However, some extent of pre-denaturation may be beneficial for the gelation performance of the soy protein samples, decreasing the gelation temperature and producing gels with higher stiffness and elastic character. On the contrary, extensive protein denaturation originate thermodynamically stable aggregates, water insoluble macro-aggregates less unfolded and dissociated by the heat treatment, being less available to integrate the three-dimensional network.
KeywordsSoybean proteins Functional properties By-products Processing effects
Sónia Monteiro acknowledges Fundação para a Ciência e a Tecnologia (FCT, Lisbon, Portugal) for a PhD Grant (SFRH/BD/24335/2005). Thanks are also due to FCT/MEC for the financial support to the QOPNA research Unit (FCT UID/QUI/00062/2013), through national founds and where applicable co-financed by the FEDER, within the PT2020 Partnership Agreement. The authors would also like to thank Dr. António Barros for the help in the principal components analysis on the FTIR spectra and the companies Iberol (Portugal) and Solae—Bunge Alimentos (Brazil) for kindly providing the soybean samples and the commercial soy protein isolates, respectively.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interests.
Compliance with ethics requirements
This article does not contain any studies with human or animal subjects.
- 25.FCC, Committee on Food Chemicals Codex, Food and Board N, Institute of Medicine (2003) Food chemicals codex. 5th edn, National Academy of Sciences, WashingtonGoogle Scholar