Relationship between digestibility and secondary structure of raw and thermally treated legume proteins: a Fourier transform infrared (FT-IR) spectroscopic study

Abstract

The secondary structure of proteins in legumes, cereals, milk products and chicken meat was studied by diffuse reflectance infrared spectroscopy in the region of the amide I band. Major secondary structure components ( β-sheets, random coil, α-helix, turns), together with the low- and high-frequency side contributions, were resolved and related to the in vitro digestibility behaviour of the different foods. A strong inverse correlation between the relative spectral weights of the β-sheet structures and in vitro protein digestibility values was measured. Structural modifications in legume proteins induced by autoclaving were monitored by the changes in the amide I spectra. The results indicate that the β-sheet structures of raw legume proteins and the intermolecular β-sheet aggregates, arising upon heating, are primary factors in adversely affecting the digestibility.

Gastrointestinal digestion of dairy and soy proteins in infant formulas: An in vitro study

“…However, the concentration of these elements is very low in soy products and could not possibly affect digestibility. Hence, the low digestibility is due to the structural aspects of soy proteins and product processing (Carbonaro, Maselli, & Nucara, 2012. The secondary structure of soy proteins is dominated by β-sheets as compared to milk proteins that are rich in α-helix.…”

“…The β-sheet structures of soy protein are highly hydrophobic and encourage protein aggregation making it less soluble and resulting in low digestibility of soy proteins. Also heat treatment during processing causes β-sheet aggregation among molecules that have adverse effect on the resistance to digestion of soy proteins (Carbonaro et al, 2012(Carbonaro et al, , 2014. Therefore, precaution should be taken when comparing the protein digestibility of soy products because its properties such as denaturation and aggregation can vary considerably between products and also between manufacturers.…”

Grain legume protein quality: a hot subject

“…Spectroscopy techniques, such as NIR (Near Infra-Red) or FT-IR (Fourier Transform Infra-Red), have been applied successfully in the measurement of several biomolecules or properties in different agricultural products, with minimal or no sample preparation (Cozzolino, 2015). Examples of such tools are beginning to be used to predict legume protein amino acid composition (Kovalenko, Rippke and Hurburgh, 2006) or in vitro digestibility (Carbonaro, Maselli and Nucara, 2012).…”

Protein quality of pig diets : processing effects on amino acid digestibility and post-absorptive utilization

“…Severe processing may lead to protein aggregation, which lowers the solubility (Carbonaro et al, 2012). The severe processing in the current study indeed reduced the NSI of the protein sources.…”

“…Protein solubility is usually reduced after processing due to increased protein aggregation Hsieh, 2007, 2008). Protein aggregation can hamper enzyme accessibility required for protein hydrolysis (Carbonaro et al, 2012;Pinto et al, 2014), which may explain the lower k values after processing. The k values were affected by the interaction between type of ingredient and processing (P = 0.01; Table 5.1) and tended to correlate with SID of CP (r = 0.91, P = 0.094).…”