Determination of the Morphology of the Starch Granules and the Optimum Internal Cooking Temperature of Four Andean Crops: Oca (Oxalis tuberosa Molina), Olluco (Ullucus tuberosus Loz), Isaño (Tropaeolum tuberosum Ruiz & Pavon) and Arracacha (Arracacia xanthorrhiza Bancroft)

Abstract

Andean grains (i.e. quinoa, amaranth) have been increasingly studied in recent times, mainly due to the increase in international consumption. However, Andean tubers other than potatoes have not been so widespread and are mainly studied for their starch, previously extracted. This work studied the morphology of native starch in four of these crops (oca, olluco, isaño and aracacha), during cooking and the evolution of their internal temperature in relation to sensory acceptability. Using scanning electron microscopy, it was determined that the size of crude starch granules was between 9 μm to 38.2 μm for oca, 4.48 to 24.9 μm for olluco, 4.45 to 22.9 μm for isaño, and 5.36 to 23.8 μm for arracacha. Sensorially, it was determined that the optimum cooking temperature for arracacha was 89.1°C, 90.9°C for oca, 91°C for isaño, and 91.4 °C for olluco. All samples had optimal cooking times shorter than potato, with the isaño having the best heat transfer.

Keywords

• starch
• scanning electron microscopy
• cooking temperature
• starch gelatinisation
• andean tubers