Author(s):
Sousa, Isabel 
; Batista, Ana Paula ; Nunes, M.C. ; Raymundo, Anabela ; Gouveia, L. ; Cordobés, F.
Date: 2010
Persistent ID: http://hdl.handle.net/10400.5/2430
Origin: Repositório da UTL
Subject(s): Spirulina; Haematococcus; microalgal biomass; pea protein; kappa-carrageenan; starch; gels
Description
Microalgae are an enormous biological resource, representing one of the most promising sources for the
development of new food products and applications. Pea protein/k-carrageenan/starch gels, interesting
vegetarian alternatives to dairy desserts, served as model systems to study the addition of microalgal
biomass, its effect, and subsequent rheological behaviour. Spirulina and Haematococcus gels presented
a markedly different rheological behaviour compared to the control mixed biopolymer gelled system.
The present goal is to clarify how these microalgae affect the gelation and interact with each biopolymer
present in the complex mixed gel system. Hence, the aim of the present work is to study the effect of
Spirulina and Haematococcus microalgal biomass addition on the rheological behaviour of pea protein, k-
carrageenan and starch simple gels, as well as in pea protein/k-carrageenan and pea protein/starch
systems. The gelation process was monitored in-situ through dynamic oscillatory measurements
(temperature, time and frequency sweep tests) for a 24 h maturation period, and rheological results were
supported with uorescence optical microscopy observations. The addition of Spirulina and Haematococcus
to biopolymer gelled systems induced signi cant changes in the gels’ rheological behaviour and
microstructure. In general, it was observed that the gelling mechanism is ruled by the biopolymers, while
microalgae seem to be embedded in the gel network acting as active particle llers. The addition of
Haematococcus resulted in more structured gels in comparison to the control and Spirulina systems. In
the case of k-carrageenan gels, both microalgae induced a large increase in the rheological parameters,
which should be related to the high ionic content of microalgal biomass. Spirulina addition on starch
systems promoted a decrease in the gels’ rheological parameters. This should be related to the starch
gelatinization process, probably by competing for water binding zones during the granules’ hydration
process
