Effects of preprocessing at low or ultralow temperatures combined with sodium alginate on retrogradation properties of normal cornstarch during chill storage

Enzymatic modification lowers syneresis in corn starch gels during freeze-thaw cycles through 1,4-α-glucan branching enzyme

The current research in the food industry regarding enzymatic modification to enhance the freeze-thaw (FT) stability of starch is limited. The present study aimed to investigate the FT stability of normal corn starch (NCS) modified using 1,4-α-glucan branching enzyme (GBE) derived from Geobacillus thermoglucosidans STB02. Comprehensive analyses, including syneresis, scanning electron microscopy, and low-field nuclear magnetic resonance, collectively demonstrated the enhanced FT stability of GBE-modified corn starch (GT-NCS-30) in comparison to its native form. Its syneresis was 66.4 % lower than that of NCS after three FT cycles. Notably, GBE treatment induced changes in the pasting properties and thermal resistance of corn starch, while simultaneously enhancing the mechanical strength of the starch gel. Moreover, X-ray diffractograms and microstructural assessments of freeze-thawed gels indicated that GBE treatment effectively hindered the association of corn starch molecules, particularly amylose retrogradation. The enhanced FT stability of GBE-modified starch can be attributed to alterations in the starch structure induced by GBE. This investigation establishes a foundation for further exploration into the influence of GBE treatment on the FT stability of starch and provides a theoretical basis for further research in this area.

Starch-guar gum-ferulic acid molecular interactions alter the ordered structure and ultimate retrogradation properties and in vitro digestibility of chestnut starch under extrusion treatment

Molecular interactions among starch and multiple-components during food processing determine the retrogradation properties and digestibility of starch. Here, the effects of starch-guar gum (GG)-ferulic acid (FA) molecular interactions on retrogradation properties, digestibility and ordered structural changes of chestnut starch (CS) under extrusion treatment (ET) were investigated by structural analysis and quantum chemistry. Due to the entanglement behaviors and hydrogen bond interactions, GG could inhibit the formation of helical and crystalline structures of CS. When FA was introduced simultaneously, FA could weaken the interactions between GG and CS as well as enter the spiral cavity of starch to increase the single/double helix and V-type crystalline structures while reducing A-type crystalline. Based on the above structural changes, ET with starch-GG-FA molecular interactions resulted in resistant starch content of 20.31% and anti-retrogradation rate of 42.98% for 21-day storage. Overall, the results could provide basic data for creation of chestnut-based food with higher value.