ORIGINAL ARTICLE Influence of Extraction Method on the Rheological Properties of Jackfruit (Artocarpus heterophyllus) Seed Starch Dispersions Carla Giovana Luciano 1 & Germàn Ayala Valencia 1 & Osvaldo H. Campanella 2 & Paulo José do Amaral Sobral 1 & Izabel Cristina Freitas Moraes 1 Received: 30 August 2017 /Accepted: 27 February 2018 # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Starches are widely used in food processing, and their rheological properties are affected by thermal conditions imposed during the process. The objective of the present study was to assess the rheological behavior of jackfruit seed starch (JSS) dispersions, with a particular interest on the effects of the starch extraction techniques using either water or an alkali solution (0.1 M sodium hydroxide) as solvents. The analyses on the starches were performed using small amplitude oscillatory shear tests, including frequency, temperature, and time sweeps, and determining flow curves at different temperatures (10–40 °C). JSS dispersions were classified as weak-intermediary gels, and those prepared with JSS extracted with water showed higher values of G’ and G^ in all of the tested samples. All gelatinized samples exhibited viscoelastic behavior, and with increasing temperatures the storage and loss moduli increased until a maximum value before reaching a plateau. Gelatinization temperatures were slightly lower for dispersions prepared with JSS extracted with water. Gelatinization kinetics showed that increasing temperatures caused a reduction in the time to achieve gelatinization. The JSS dispersions displayed thixotropic behavior, which was influenced by their concentration and the extraction method employed. The flow curves exhibited pseudoplastic behavior. The Power Law model was used to describe the JSS dispersions rheological behavior, which enabled to assess the effects of starch concentration and extraction method on their rheological properties. Keywords Jackfruit . Rheology . Flow curve . Oscillatory shear . Viscoelasticity Introduction Starch is widely used in food processing and food formula- tion, as thickener and bulking ingredients and as a gelling agent, since it can generate viscous dispersions, solutions, or gels, depending on its botanical origin, concentration, and temperature conditions [1–4]. Native starch undergoes a variety of physicochemical and rheological changes during thermal processing, commonly known as gelatinization and pasting [5]. These changes in- volve the leaching of macromolecular components out of granules, which are disrupted by thermal energy and the application of shear forces [6]. The rheological properties of starch dispersions determine their functionality and are signif- icantly influenced by the amylose/amylopectin ratio, granule swelling, and the degree of gelatinization, which depends on the temperature and amount of water present in the dispersion [7, 8]. The effect of temperature on the physicochemical and rhe- ological properties of starch dispersions has been studied ex- tensively, as well as the characterization of starches derived from non-conventional sources in order to establish and im- prove their use in processed food-products [9–11]. An exam- ple of a non-conventional starch source is that obtained from jackfruit seeds. Jackfruit is a tropical fruit originated from Asia, which is highly consumed in Brazil. Starch from its seeds has been studied in regards to its morphological, phys- icochemical, and functional properties [12–15]. Luciano et al. [16] extracted starch from jackfruit seeds and determined a yield of approximately 23.0 g/100 g of seeds (dry basis). Moreover, the assessed starch had 0.6 g of lipids/100 g of starch; 1.7 g of proteins/100 g of starch, and 29.1 g of * Izabel Cristina Freitas Moraes bel@usp.br 1 Department of Food Engineering, School of Animal Science and Food Engineering, University of São Paulo, Pirassununga, SP, Brazil 2 Department of Food Engineering, Purdue University, Lafayette, IN, USA Food Biophysics https://doi.org/10.1007/s11483-018-9521-z