Morphology and mechanical behaviour of pea-based starch-protein composites obtained by extrusion. (1st November 2019)

• Record Type: Journal Article
• Authors: Jebalia, I.; Maigret, J.-E.; Réguerre, A.-L.; Novales, B.; Guessasma, S.; Lourdin, D.; Della Valle, G.; Kristiawan, M.
• Is Part Of: Carbohydrate polymers. Volume 223(2019)
• Publication Date: 2019-11-01
• Subjects: a* redness in CIELAB colour space -- b* yellowness in CIELAB colour space -- C torque (N.m) -- CLSM confocal laser scanning microscopy -- D50 median protein aggregate width (μm) -- Db dry basis -- DSC differential scanning calorimetry -- E flexural modulus (GPa) -- F force (N) -- H die thickness (m) -- H specimen width (mm) -- Ii interface index -- L* lightness in CIELAB colour space -- L support span in bending test (mm) -- MC moisture content (wb) -- N screw speed (rpm) -- NF native pea flour -- NSPB native starch-protein blend -- PPI pea protein isolate -- RH relative humidity (%) -- Q measured total mass flow rate (kg/h) -- QF mass flow rate of raw materials (kg/h) -- Qv volumetric flow rate (m3/s) -- QW mass flow rate of water (kg/h) -- SP blend starch-protein blend -- T product temperature (°C), measured at die entrance -- Tdie imposed die temperature (°C) -- th specimen thickness (°C) -- Tm melting temperature (°C) -- T5 imposed temperature in the fifth barrel (°C) -- SME specific mechanical energy (kJ/kg) -- W die width (m) -- wb wet basis -- ΔP pressure drop inside the die (Pa) -- σ engineering stress (Pa) -- ε engineering strain (%) -- η apparent viscosity (Pa.s); Bending test -- Composite -- Interface -- Microstructure -- Protein aggregates -- Starch; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2019.115086
• Languages: English
• ISSNs: 0144-8617

Abstract

Graphical abstract: The composites mechanical properties are controlled by the starch-protein interface index which is governed by the specific mechanical energy (SME). Highlights: Pea composites were extruded in a large interval of specific mechanical energy SME. Various starch/protein composite morphologies can be obtained by modifying SME. An interface index is defined to describe composite morphology. The composites mechanical properties strongly depend on interface index. Abstract: Starch-legume protein composites were obtained by extrusion of pea flour and pea starch-protein blend at various specific mechanical energies (100–2000 kJ/kg) and a temperature low enough to avoid expansion. The morphology of these composites displayed protein aggregates dispersed in a starch matrix, revealed by microscopy. Image analysis was used to determine the median width of protein aggregates ( D50 ), their total perimeter and surface, from which a protein/starch interface index ( Ii ) was derived. The mechanical properties of composites were determined by a three-point bending test. The pea flour composites had a higher interface index Ii (1.8–3.1) with lower median particle width D50 (8–18 μm) and a more brittle behaviour than the blend composites that had a lower Ii (1–1.1) and higher D50 (22–31 μm). For both materials, rupture stress and strain were negatively correlated with Ii . This result suggested that there was a poor interfacial adhesion between the pea starch and proteins.