Extraction and characterization of starch from low-grade potatoes and formulation of gluten-free cookies containing modified potato starch

Potatoes are among the leading staple crops due to nutritional value and high demand. The undersized and damaged potatoes are considered low grade and mainly dumped as a waste or used in animal feed. The study aimed to extract starch from low grade potatoes, its modification to improve the starch properties and formulation of gluten free cookies using modified starch (MS). The starch was extracted from low-grade potatoes of three varieties known as Asterix, Kruda and Mosaic, using the water steeping method. The native starch (NS) was modified using lintnerization and repetitive autoclaving. MS contains high amylose content which is associated with health benefits. NS and MS were characterized for amylose content, color attributes, granular morphology, water solubility index (WSI), water absorption index (WAI), thermogravimetric analysis (TGA) and Fourier transform infrared spectrometer (FTIR) analysis. Gluten-free cookies were formulated by adding potato NS and MS. The cookies were characterized by sensory evaluation, proximate and textural analysis. The starch yield extracted from three different varieties of potatoes i.e. Asterix, Kruda, Mosaic was 11.53%, 11.32% and 11.24%, respectively. The amylose content of potato starch was significantly (p < 0.05) increased for all varieties (33.61–37.74%) after modification of NS, which was in the range of 25.71–26.60% for different potato varieties. The granules of MS were observed as amorphous structures in comparison to NS granules with smooth surfaces. The addition of MS significantly (p < 0.05) decreased the hardness of the cookies in comparison to NS. Overall, no significant difference was observed in the sensory attributes of control, NS and MS containing cookies. Therefore, in comparison to other dietary fibers, MS can be used as a functional ingredient in food products without compromising the texture and sensory attributes.