Isolated sweetpotato starch properties from roots used to make sweetpotato French fries

Published: 29 September 2022| Version 1 | DOI: 10.17632/nzjrcgt9kp.1


These are data of isolated sweetpotato starch granule sizes, amylopectin branching distributions (peak area ratios and molar ratios), and thermal differential scanning calorimetry scans (raw and deconvolution data) that were used in the manuscript "Impact of sweetpotato starch structures, thermal properties, and granules sizes on sweetpotato fry textures" by Allan, Read, and Johanningsmeier. Starches were isolated from the roots used in Sato, A., Truong, V.-D., Johanningsmeier, S. D., Reynolds, R., Pecota, K. V., & Yencho, G. C. (2018). Chemical constituents of sweetpotato genotypes in relation to textural characteristics of processed French fries. Journal of Food Science, 83(1), 60–73.


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Full Methods will be published in "Impact of sweetpotato starch structures, thermal properties, and granules sizes on sweetpotato fry textures". Amylopectin chain length distribution: 10mg of starch in 5ml 90% DMSO, heat at 100˚C for 20 min, cool on ice for 1-2 min, add 5 mL of cold 100% ethanol, mix, and hold on ice for 30 min. Centrifuge at 6000g for 10 min at 10˚C, discard supernatant, redissolve precipiate in 4 mL of water and heat at 100˚C for 1 h. Add 1 mL of acetate buffer and sodium azide stock solution for a final concentration of 50 mM acetate buffer at pH 4.5 and 0.02% sodium azide. Add 30 μL of Isoamylase HP (about 15 U) to a 1.5 mL aliquot in a 2 mL microcentrifuge tube, mix in thermomixer at 40˚C and 1000 rpm for 24 h, then stop reaction by heating to 99/100˚C. Filter solution through 0.45μm nylon syringe filters into HPLC vials. HPLC Method: CarboPac-PA1 with guard column at 30˚C at a flow rate of 1 ml/min. Mobile phase A was 150 mM sodium hydroxide and mobile phase B was 150 mM sodium hydroxide and 500 mM sodium nitrate. Gradient method: 0-5min 3% B, 5-10 min linear ramp to 8% B, 10-30 min linear ramp to 13% B, 30-60 min linear ramp to 20% B, 60-65 min linear ramp to 30% and held for 1 min, then 20 min at 3% B. Differential Scanning Calorimetry: 10μL of 1:2 w/w starch to water slurries that was equilibrated overnight and heat from 10 to 105˚C at 10˚C /min. Peak deconvolution was performed with “Interactive Peak Fitter” (O’Haver, 2021) in MatLab R2019b (The MathWorks, Inc., Santa Clara, CA, USA). First adjust baseline of thermogram before and after the gelatinization event, identify the approximate location of peaks, fit using the fixed width Gaussian fit, then test with 10 rounds of bootstrapping. Starch granule particle size analysis: Measure granule sizes using a Malvern Mastersizer 3000 with a Hydro EV wet dispersion attachment (Spectris, Egham, UK). Equilibrate starch slurries for >12 h, add to dispersing unit until ≈10% obstruction, then measure particle sizes 5x using 10s measurements. Calculate the percent volume density of hydrated starch granules using 1.3 g/cm3 density of hydrated starch (Dengate, Baruch, & Merdith, 1978) with particles from 1 to 100 μm.


USDA Agricultural Research Service


Starch, Starch Gelatinization, Sweet Potato, Amylopectin