Effect of Starch Isolation Method on Structural and Physicochemical Properties of Acorn Kernel Starch

Abstract

Starch is isolated from kernel of acorn fruit (Quercus fabri) using different methods, including hot‐water soaking (HWS), alkaline washing (ALW), ultrasonic‐assisted ethanol soaking (UAES), and ultrasonic‐assisted hot‐water soaking (UAWS). Structural and physicochemical properties of starches isolated using these methods are investigated. The surface structure of acorn starch granules varies depending on the isolation method. However, a similar C‐type crystalline pattern is found for all the isolated starch samples. Acorn starches isolated using the ALW and UAES methods exhibit a greater degrees of crystallinity than those of starches isolated using the other methods. FT‐IR spectra analysis reveals that the chemical bonds in starch molecules are not affected during the isolation of acorn starch under different conditions. Moreover, starch isolated using the UAES method exhibits the greatest water solubility, swelling power, and light transmittance values, as well as the lowest tannin content. In addition, the lightest white color is found for starch isolated using the ALW method. Furthermore, the HWS and ALW methods result in acorn starch with greater enthalpy and gelatinization temperatures, whereas the UAES and UAWS isolation methods result in acorn starch with greater peak viscosity. The obtained results provide important knowledge about the differences in physicochemical properties of acorn starch isolated using different methods.

Composition, Physicochemical Properties, and Uses of Acorn Starch

“…A-type polymorph was reported for acorn starch [7,23,24,27,28]. C-type polymorph was also noted [19,25,33,43]. e degree of crystallinity of acorn starch ranged between 22.3 and 47.8% (Table 2).…”

“…Li et al [7] described a method of isolation of starch from acorn which included steeping of acorn flour in 0.3% sodium hydroxide (1 : 5, w/w), screening of the dispersion through a mesh sieve a 0.18 mm, and then purification by centrifugation. It should be noted that the physicochemical properties of acorn starch are more affected by differences in isolation method and experimental conditions [32][33][34]. e starch yield was in range of 48.93 to 89.83% [28,32,35].…”

“…Starch isolation method may have effect on property (SP) and solubility of starch. Acorn starch isolated using the ultrasonic-assisted ethanol soaking (UAES) showed a relatively higher value swelling power and solubility compared with other methods; they were about 24.99 g/100g and 15.22%, respectively, at temperature 90°C [33]. Acorn starch has a low swelling power when compared to potato starch.…”

Effects of ultra‐high pressure on the morphological and physicochemical properties of lily starch

“…The lily bulb starch was extracted according to Zhang, Saleh, et al (2020) with some modifications. The well‐homogenized lily slurry was filtered with a 100 mesh nylon cloth, and the residue was rinsed repeatedly with distilled water until no more starch filtrate was released.…”

The Rheological Performance and Structure of Wheat/Acorn Composite Dough and the Quality and In Vitro Digestibility of Its Noodles

“…The addition of functional flour obtained from acorns in bread, cake, and biscuit have been recently evoked [5,10]. However, Acorn is rich in tannin, which generates the inedible astringent taste and behaves as an anti-nutrients, and appropriate methods are required to remove it [11]. Furthermore, acorn flour contains no gluten proteins, which confer viscoelasticity to the dough, while wheat proteins pose unique viscoelastic characteristics during dough preparation and are extensively used in food products [12].…”