Comparative analysis of thermal, structural and rheological properties of protein isolates and kernel flour from Australian sweet lupin varieties using soy as a reference
Piyumi Chathurangi Wanniarachchi , Mauro Mocerino , Mark J. Hackett , Michael Nesbit , Greg Shea , Ranil Coorey
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引用次数: 0
Abstract
This study demonstrates the thermal, structural, and rheological properties of flours and protein isolates of five Lupinus angustifolius L. varieties using soy flour and protein isolate as references. Fourier transform infrared (FTIR) analysis of lupin protein isolates in the amide I region revealed significantly higher β-sheet content than α-helices, together comprising ∼50 % of the secondary protein structures. In differential scanning calorimetry (DSC), lupin flour exhibited two distinct peak denaturation temperatures (Td), first between 90 and 91 °C, second between 103 and 105 °C. Similarly, for lupin protein isolates, the two Tds were at 84–86 °C and 96–98 °C, which represent β-conglutin and α-conglutin, respectively. The microstructure of lupin proteins was less interconnected than soy, which had a more compact and continuous protein network. Lupin protein isolates form a weaker and easily deformed gel network compared to soy protein isolates due to their lower complex viscosity (ŋ∗), storage (G′) and loss (G") moduli, and higher loss factor (tan δ) compared to soy protein isolates. Flours were characterised as more frequency-dependent than protein isolates, indicating weaker gel networks. Rapid viscosity analyser (RVA) profiles revealed that lupin flours exhibited higher peak (237.00–265.00 cP) and final viscosities (3.38–4.89 cP) than soy flour (166.33 cP and 1.11 cP, respectively), indicating the influence of non-starch components on enhanced pasting properties in lupin flours. Since lupin proteins form weaker gels than soy, process modulations are essential to improve their functionality in food products. Moreover, higher Td associated with lupin flour over soy flour demonstrate greater thermal stability, which is potentially beneficial in heat-processed, high-protein products.
期刊介绍:
Food Hydrocolloids publishes original and innovative research focused on the characterization, functional properties, and applications of hydrocolloid materials used in food products. These hydrocolloids, defined as polysaccharides and proteins of commercial importance, are added to control aspects such as texture, stability, rheology, and sensory properties. The research's primary emphasis should be on the hydrocolloids themselves, with thorough descriptions of their source, nature, and physicochemical characteristics. Manuscripts are expected to clearly outline specific aims and objectives, include a fundamental discussion of research findings at the molecular level, and address the significance of the results. Studies on hydrocolloids in complex formulations should concentrate on their overall properties and mechanisms of action, while simple formulation development studies may not be considered for publication.
The main areas of interest are:
-Chemical and physicochemical characterisation
Thermal properties including glass transitions and conformational changes-
Rheological properties including viscosity, viscoelastic properties and gelation behaviour-
The influence on organoleptic properties-
Interfacial properties including stabilisation of dispersions, emulsions and foams-
Film forming properties with application to edible films and active packaging-
Encapsulation and controlled release of active compounds-
The influence on health including their role as dietary fibre-
Manipulation of hydrocolloid structure and functionality through chemical, biochemical and physical processes-
New hydrocolloids and hydrocolloid sources of commercial potential.
The Journal also publishes Review articles that provide an overview of the latest developments in topics of specific interest to researchers in this field of activity.