Starches Isolated from Potatoes Grown in Chile: Characterisation and Nanoparticle Preparation

Abstract

The most widely cultivated varieties of potato in Chile are Patagonia and Asterix. However, there is scarce information about the physical–chemical characteristics of starches isolated from these potatoes. In this study, the starches from two potato varieties, Patagonia and Asterix, were isolated and characterised. In addition, an exploratory study of the preparation of starch nanoparticles from these potato varieties by the flash nanoprecipitation method was performed. The morphology (scanning electron microscopy and optical microscopy), crystallinity (X-ray diffraction), thermal (differential scanning calorimetry), rheological (rapid visco analyser) and hydration properties are reported. Starches from Patagonia potato (PPS) and Asterix potato (APS) were isolated by the wet milling method. PPS and APS had similar starch content on fresh weight basis, around 15%. The granule particle sizes of Chilean potato starches showed a unimodal distribution, in the range of 10–90 µm. Amylose content varied between 23.8 and 25.3% for APS and PPS, respectively, making them normal starches. Gelatinisation temperature and enthalpy were 58.6 and 60.1 °C and 15.5 and 17.8 J/g for APS and PPS, respectively. Significant differences were obtained in the pasting parameters of Chilean potato starches; the rapid visco analyser pasting profiles of PPS exhibited a large viscosity peak and APS did not show a distinctive viscosity peak. The pasting profiles of APS are required for food products such as soups and sauces. Spherical nanoparticles were prepared from the Chilean potato starches by flash nanoprecipitation method using two micromixer devices: confined impinging jet mixer and multi-inlet vortex mixer. The size of potato nanoparticles depended on micromixer device, and the lowest particle size (100 nm) was obtained when the confined impinging jet mixer was used. The nanoparticles from Chilean potato starches are potential raw materials for the nutraceutical, food and pharmaceutical fields.