Tailoring Digestibility of Starches by Chain Elongation Using Amylosucrase from Neisseria polysaccharea via a Zipper Reaction Mode

Abstract

Amylosucrase from Neisseria polysaccharea (NpAS) was applied to modify waxy corn starch (WCS) and irradiated WCS, whose attenuated digestibility was studied. Herein, the mobility of the reaction mixture did not affect the enzyme catalytic efficiency, and the reaction kinetics suggest that the enzyme elongated the starch chain via a zipper reaction mode. The A-type crystalline structure of native and irradiated WCS was changed to B type after NpAS treatment, and a longer chain length led to a further increase in the gelatinization temperature. Chain elongation increased the content of resistant starch (RS) from 22.3% (native WCS) to be as much as 64.4% for NpAS-modified WCS, accordingly decreasing the contents of both rapidly and slowly digestible starches. Pearson correlation analysis implies that the RS content of NpAS-modified starches was positively and negatively correlated to the proportion of intermediate chains [13 ≤ degree of polymerization (DP) ≤ 24] and short chains (DP ≤ 12), respectively.

Physicochemical Properties of the Rice Flour and Structural Features of the Isolated Starches from Saline-Tolerant Rice Grown at Different Levels of Soil Salinity

“…Crystalline structure was analyzed by a D2 PHASER X-ray diffractometer at 20 mA and 40 kV with a step size of 0.02 over an angular range of 5–40°. The isolated rice starches were equilibrated at 100% relative humidity prior to analysis, and the relative crystallinity was calculated using a two-phase method . The lamellar structure of starch granules was characterized by an Anton Par SAXSpoint 2.0 system (Anton Par, Graz, Austria) with sample moisture being adjusted to 45% .…”

“…The pasting properties of the flour from saline-tolerant rice were analyzed using an RVA-4500 rapid visco analyzer (Perten, Australia). 20 The obtained rice flour was mixed with distilled water at a mass ratio of 9.2%, with a total weight of 28 g. The suspension was held at 50 °C for 1 min and then heated to 95 °C at a rate of 6 °C/min. The hot paste was kept at 95 °C for 5 min and subsequently cooled back to 50 °C and finally maintained at 50 °C for 2 min.…”

“…The isolated rice starches were equilibrated at 100% relative humidity prior to analysis, and the relative crystallinity was calculated using a two-phase method. 20 The lamellar structure of starch granules was characterized by an Anton Par SAXSpoint 2.0 system (Anton Par, Graz, Austria) with sample moisture being adjusted to 45%. 23 The lamellar structure of the isolated rice starches was analyzed by a one-dimensional correlation function as follows = L r I q q qr q I q q q ( )…”

Influence of Electron Beam Irradiation on the Moisture and Properties of Freshly Harvested and Sun-Dried Rice

“…The digestibility of the starch samples was mainly determined in accordance with the method of Englyst and Wang [ 19 , 20 ] with some modifications. A 100 mg starch sample was added into a screw-cap tube and treated with 4 mL of digestive juice.…”