Influence of Technological Modifications of the Protein Network from Pasta on in vitro Starch Degradation (original) (raw)

1999, Journal of Cereal Science

The pasta protein network limits starch hydrolysis rate in vivo leading to low post-prandial glycemia. To better understand the mechanisms involved, various pasta products were processed to obtain protein network structures differing from that in reference pasta extruded at 40°C and dried 17 h at 55°C. After cooking, pasta strands were submitted to in vitro alpha-amylolysis. Compared to reference pasta, higher extrusion temperature (70°C), high-temperature drying treatment (2 h at 90°C) or autoclaving (115°C for 15 or 40 min) had no marked effect on the rate of dextrin release from pasta particles. Protein enrichment at a 20%-level and flour fractionation-reconstruction with removal of insoluble fibre before pasta extrusion significantly (p<0·05) delayed ([1 h) the rate of dextrin release (−14% at 8 h). Confocal laser scanning microscopy allowed the three-dimensional structure of the protein network from protein-enriched pasta to be observed, and suggested that increased starch encapsulation may explain the reduced accessibility of starch to alpha-amylases. A stronger cohesiveness between starch and protein, due to insoluble fibre removal, was probably responsible for the decrease of starch accessibility to alpha-amylase in fractionated-reconstructed flour pasta. Modified geometrical characteristics (e.g., tortuosity) of the protein network were not correlated with starch degradation rates.

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