Changes in the multi‐scale structure and physicochemical properties of starch during potato growth

Abstract

BACKGROUND: Growth stage contributes critically to the physicochemical properties of starches, which make achieving desired functional properties by controlling the growth period possible. Thus, this study investigated the changes in multiscale structure and physicochemical properties of potatoes starches harvested at different growth stages. RESULTS:The amylose and phosphate content varied over the growth period, with the ranges 2.756-2.998 g kg −1 and 0.0058-0.0077 g kg −1 , respectively. The starch granules were round or oval, and the size increased with growth. X-Ray diffraction indicated the B-type crystalline structure of samples. Time-dependent changes in crystallinity were observed. The weight-average molecular weight (M w ) showed a tendency to decrease first and then increase, and presented the lowest M w (1.105 × 10 8 g mol −1 ) at 35 days. A higher proportion of long chains were noted in starch from earlier harvested potatoes than that in later harvested ones. Differential scanning calorimetry revealed that starch gelatinization temperature decreased, and gelatinization enthalpy decreased from 16.39 to 14.89 J g −1 . All samples possessed weak elastic gel-like structure, and starches harvested at early stage possessed highest viscosity and stronger gel behaviour. Resistant starch showed a decreasing trend on the whole, and presented highest value (10.69%) at earliest harvest time. Starch from the potatoes harvested at 35 days after tuberization exhibited excellent light transmittance (up to 62.47%). CONCLUSION:Potato starches harvested at different growth period presented extremely different structures and physicochemical properties. The results will provide fundamental data in terms of changes of potato starch during growth which will affect the choice of harvest time.

Effect of Heat-Moisture Treatment on the Physicochemical Properties and Starch Digestibility of Mix Powder (Wheat Flour-Black Soybean Flour) and Corresponding Cookies

“…The crystalline peak area and amorphous area were separated by PeakFit software (Version 4.12, Systat Software Inc., San Jose, CA, USA). The relative crystallinity of the samples was calculated as the ratio of the crystalline peak area to the total diffraction area [ 15 ].…”

“…The thermal properties of the wheat flour, mix powder, and HMT-mix powder were measured using a differential scanning calorimeter (Model DSC3, Mettler-Toledo, Greifensee, Switzerland). The method was referred to Yang et al [ 15 ] with some modifications. Briefly, 3 mg of starch and 9 μL of distilled water were added into an aluminum pan and hermetically sealed.…”

“…The cookies were ground into powders to determine the in vitro starch digestibility. The enzymatic hydrolysis of the cookies was determined as described by Yang et al [ 15 ].…”