Application of high-pressure homogenization to steer the technological functionalities of chia fibre-protein concentrate

Abstract

Chia is an excellent source of healthy constituents (dietary fibre and proteins) with high water holding capacity (WHC) and strong gelling properties, which imply technological challenges for its application in foods, such as leavened bakery products. Therefore, this work explored the potential of high-pressure homogenization (HPH) to steer the technological functionalities (physicochemical, structural and rheological properties) of a chia fibre-protein concentrate (FPC) for food applications. Chia FPC suspensions (5%, w/w) were treated at increasing pressures (up to 150 MPa) and number of cycles (up to 5) to generate a wide range of energy densities delivered to the sample during processing (100–750 MJ m−3). HPH treatments decreased particle size, WHC and oil holding capacity of FPC. WHC of treated samples was 52–70% lower than control. Moreover, rheological measurements on the soluble fraction of homogenised FPC showed a reduction in apparent viscosity and shear-thinning behaviour. These results can be attributed to multiple events occurring during HPH processing. In particular, the mechanical forces suffered by the samples induced the rupture of native structures in smaller fragments in concomitance with biopolymer structure modifications. HPH at energy densities between 300 and 750 MJ m−3 determined a 14–35% increase in soluble dietary fibre (SDF) compared to control, indicating a partial conversion from insoluble to SDF without changes in total dietary fibre. Conformational changes in proteins were also observed. This study suggests that proper selection of HPH energy density represents a strategy to obtain novel promising ingredients rich in dietary fibre and proteins with tailored technological functionalities.