Functionalisation of pea protein by tryptic hydrolysis – Characterisation of interfacial and functional properties

Abstract

With regard to applications in dispersed systems (i.e. emulsions), improving the poor solubility of pea protein in the pH-range applicable to foods (pH 3 to pH 7) is a prerequisite. To achieve this, a pea protein concentrate was produced on a lab scale using alkaline extraction and subsequent enzymatic hydrolysis to degrees of 2 and 4%. Solubility was improved and interfacial properties were influenced. All samples led to the formation of emulsions but displayed a tendency towards wider oil-droplet size distributions at pH close to the isoelectric point. Using microscopy, this increase could be attributed to the formation of aggregates, which in turn can be ascribed to lack of repulsion caused by the low absolute values of ζpotentials. The same lack of repulsion led to stronger and more elastic interfacial films at pH 4 and 5 than at pH 7. Moreover, film strength increased significantly with increasing degree of hydrolysis. Dilatational experiments imply that hydrolysis enhances in-plane structural rearrangements. Thus, it is concluded that tryptic hydrolysis has the potential to improve the overall stability of emulsions.

Physical Stability and Interfacial Properties of Oil in Water Emulsion Stabilized with Pea Protein and Fish Skin Gelatin

“…However, on day 3, a decrease in ζ-potential of 2 and 8 mV was observed for A and E, respectively. Similar values were founded by Klost & Drusch [48] for O/W emulsions at pH 3. They detected a ζ-potential of 30 mV for pea extracted with an alkaline method.…”

Structure formation and rheological properties of pea protein-based gels

“…Pea protein was produced on lab scale as previously described in more detail (Klost & Drusch, 2019). Briefly, dry peas were ground and the flour was dispersed in 0.0375 M NaOH leading to an initial pH value of approximately 8.7 which dropped to just above pH 8 during the extraction time.…”

“…When rapeseed oil was added to the samples, the oil was emulsified by the protein during the homogenisation step before fermentation. From a previous study (Klost & Drusch, 2019) we know that a protein content of 1% is sufficient to stabilise 5% rapeseed oil. Samples in the current study contained 10% protein and 4% oil, leading to sufficient bulk protein for network formation.…”

In Vitro and In Silico Antioxidant Activity of Novel Peptides Prepared from Paeonia Ostii ‘Feng Dan’ Hydrolysate

“…Figure 1B demonstrates that the 23, 33 and 34 kDa proteins are the main components of Po SMP, followed by 38 and 49 kDa proteins. The 34 kDa band with the highest protein content was conveniently hydrolysed by alcalase and pepsin, which suggested that the band may have a large number of amino acids at the two enzyme cleavage sites or related to the hydrolysis condition [30]. In contrast, proteins at 23 and 38 kDa showed strong resistance to most of the selected enzymes, and only pepsin could hydrolyse under acidic conditions, which may be related to the spatial structure and special functions of the proteins [31].…”