Synthesis, characterization, and antioxidant activity of caffeic‐acid‐grafted corn starch

Abstract

The antioxidant molecule of caffeic acid was grafted onto corn starch by an N,N 0 -carbonyl diimidazole-mediated reaction. The structural, crystalline, thermal, and antioxidant properties of caffeic-acid-grafted starch (caffeic acid-g-starch) were investigated. The grafting ratio of caffeic acid-g-starch was determined as 66.1 mg/g by the Folin-Ciocalteu method. The Fouriertransform infrared spectrum of caffeic acid-g-starch exhibited a band at 1720 cm À1 attributed to the vibration of the esterified carboxyl group, and bands from 1440 to 1633 cm À1 attributed to the stretching of the aromatic ring. The 1 H nuclear magnetic resonance spectrum of caffeic acid-gstarch showed all the characteristic signals of starch at d 3.30-5.47 ppm, and methine protons of caffeic acid moieties at d 6.77-7.33 ppm. Caffeic acid-g-starch was piece or virgate in shape with a rough surface as observed by scanning electron microscopy. The X-ray diffraction pattern of caffeic acid-g-starch showed an amorphous character. The small-angle X-ray scattering pattern further indicated the semi-crystalline growth rings in native starch were disrupted during the synthetic processes. Thermogravimetric analysis showed caffeic acid-g-starch had a higher thermal stability than native starch. Moreover, the reducing power and free-radical scavenging activity of native starch were greatly enhanced after grafting with caffeic acid. These results suggest the potential of caffeic acid-g-starch as a novel antioxidant agent.

Structure and in vitro digestibility on complex of corn starch with soy isoflavone

“…The weight loss of the third and fourth stages, might be due to decomposition of SI residues, and decomposed SI molecules need a period of time to reach a constant weight, so that the mass loss slowly (Zhang et al, 2011). high decomposition temperature proves stronger thermal stability (Liu & Wang, 2017). In this study, the thermal stability of starch was improved after adding soy isoflavone.…”

“…Compared with SSI‐0, decomposition temperature of CS‐SI complexes increased from 315°C to 320°C. The decomposition temperature of starch is related to its crystal type, processing method, chemical modification, and relative molecular mass, and high decomposition temperature proves stronger thermal stability (Liu & Wang, 2017). In this study, the thermal stability of starch was improved after adding soy isoflavone.…”

Bioactive Starch Foam Composite Enriched With Natural Antioxidants from Spent Coffee Ground and Essential Oil

“…During coffee production, spent coffee ground (SCG) is generated as a major waste . SCG has been used for various applications that is, production of active carbon, reinforcing phase in polymer composite and raw material for antioxidant extractions . Yen et al reported that roasted coffee residue extracted by water showed the highest yield of antioxidants for protection of lipid per oxidation compared with other organic solvents.…”

“…[13] SCG has been used for various applications that is, production of active carbon, reinforcing phase in polymer composite and raw material for antioxidant extractions. [14][15][16][17][18] Yen et al [19] reported that roasted coffee residue extracted by water showed the highest yield of antioxidants for protection of lipid per oxidation compared with other organic solvents. The components of extracted roasted coffee residue consisted of both phenolic compound including chlorogenic acid and caffeic acid as well as non-phenolic compound namely caffeine, trigonelline, nicotinic acid, and 5-(hydroxymethyl)-2-furfuraldehyde.…”

Synthesis and Some Physico‐Chemical Properties of Novel Starch‐g‐poly(citronellyl acrylate) Copolymers

“…The copolymers of carbohydrate polymers, e.g., starch, cellulose, dextran, carboxymethylcellulose, lignocellulose, alginate, chitosan, etc. and various structure vinyl monomers, e.g., styrene, methacrylates, acrylates can be synthesized . In addition, the graft copolymers of synthetic polymers such as (poly(chloroethyl vinyl ether)‐g‐polystyrene)comb‐b‐(poly(chloropyran ethoxy vinyl ether)‐g‐polyisoprene)comb, (meth)acrylate copolymer grafted with long fluorinated side chain, Nylon 6‐g‐poly(acrylic acid), polyethylene‐g‐poly(acrylic acid), polyaniline‐g‐(sulfonated polyurethane), poly(N‐vinylpyrrolidinone‐g‐styrene), etc.…”