Protein gels and emulsions from mixtures of Cape hake and pea proteins.
BACKGROUND
Portioning of frozen fish generates by-products such as fish 'sawdust' and cut-offs which can be further processed into protein concentrates and isolates. The objective of the present work was to produce gels and emulsions using recovered Cape hake protein powder (HPP). In previous works, the structures of the gels produced by HPP were found to be strong, with a high rubbery character. In this work, the addition of commercial pea proteins (PPC) to HPP gels and emulsions was studied.


RESULTS
Physical properties of gels and emulsions prepared with different proportions of mixtures of PPC and HPP were evaluated. In general, gels and emulsions showed high values for whiteness and, as expected, the higher content of HPP in the protein mixtures led to higher firmness values of the gels. The gel network was rapidly formed upon heating due to the fish protein macromolecules and further reinforced by the pea protein macromolecules when cooled to 5 °C. Both visco-elastic parameters, storage and loss moduli, of the produced gels increased with the HPP proportion in the protein mixtures, corresponding to more structured systems. For the emulsions, two different pH environments were studied: 3.8 and 7.0. At neutral pH a synergy was found between the vegetable and fish protein, which is not so strong when pH is lowered to 3.8, near the isoelectric point of pea proteins (pI = 4.5). This evidence was supported by the results from the texture measurements, viscosity and visco-elastic parameters.


CONCLUSIONS
Gels made from Cape hake proteins showed a softer texture and were less rubbery with the addition of pea proteins. Emulsions stabilised by these mixtures showed slightly different behaviour when produced at pH 7.0 or pH 3.8.
CEER - Biosystems Engineering, Instituto Superior de Agronomia/Technical University of Lisbon, Tapada da Ajuda, 1349-017, Lisbon, Portugal.
Ana Sofia
AS
Tomé
Carla
C
Pires
Irineu
I
Batista
Isabel
I
Sousa
Anabela
A
Raymundo
D000818:Animals; D003116:Color; D004044:Dietary Proteins / Q000737:chemistry*; D019587:Dietary Supplements; D004655:Emulsions / Q000737:chemistry; D029941:Fish Proteins / Q000737:chemistry*; D005511:Food Handling; D048388:Gadiformes; D005782:Gels / Q000737:chemistry; D006244:Hardness; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D018532:Pisum sativum; D010940:Plant Proteins / Q000737:chemistry*; D011208:Powders; D012212:Rheology; D012639:Seeds; D013696:Temperature; D014783:Viscosity; D014867:Water
D004044:Dietary Proteins; D004655:Emulsions; D029941:Fish Proteins; D005782:Gels; D010940:Plant Proteins; D011208:Powders; D014867:Water
Cape hake by-products; gels and emulsions; pea proteins; recovered proteins; texture and rheological properties