title: Physicochemical properties of partially oxidized corn starch from bromide-free TEMPO-mediated reaction.
abstract: This study was conducted to determine the optimal temperature and time for the regiospecific oxidation of primary alcohol groups in corn starch with 2,2,6,6-tetramethyl-1-piperidinyl oxoammonium ion (TEMPO) and sodium hyphochlorite (NaOCl). The study also elucidated the molecular structure of fully oxidized corn starch (FOCS) prepared at optimum temperature and physicochemical properties of the partially (10%, 20%, and 30%) oxidized corn starches (POCS). The reaction time rapidly decreased up to 30 degrees C, and then gradually decreased. Selectivity, yield, and viscosity were drastically reduced at temperatures higher than 35 to 40 degrees C. Optimal oxidation temperature for the production of FOCS was determined as 35 degrees C. Regiospecific oxidation of the primary alcohol group without oxidation of the secondary alcohol group was confirmed in (13)C-NMR and IR spectra. Water-binding capacity, swelling power, solubility power, and transmittance of POCS increased as the degree of oxidation increased. Hardness, gumminess, and chewiness of corn starch gel containing POCS were not significantly different from those of native corn starch gel at 1-d storage, but the values of the starch gel containing POCS were smaller than those of the native starch gel after 1-d storage. However, springiness and cohesiveness did not differ significantly among the samples regardless of storage time.
authors.affiliation: Department of Food Science and Technology, Seoul National University of Technology, Seoul 139-743, South Korea.
authors.forename: P S
authors.initials: PS
authors.lastname: Chang
authors.forename: K O
authors.initials: KO
authors.lastname: Park
authors.forename: H K
authors.initials: HK
authors.lastname: Shin
authors.forename: D S
authors.initials: DS
authors.lastname: Suh
authors.forename: K O
authors.initials: KO
authors.lastname: Kim
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D002247:Carbon Isotopes; D003497:Cyclic N-Oxides / Q000737:chemistry*; D005519:Food Preservation / Q000379:methods*; D005524:Food Technology / Q000379:methods; D005782:Gels; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012973:Sodium Hypochlorite / Q000737:chemistry*; D012995:Solubility; D013213:Starch / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013696:Temperature; D013997:Time Factors; D014783:Viscosity; D003313:Zea mays / Q000737:chemistry
chemical_list: D000975:Antioxidants; D002247:Carbon Isotopes; D003497:Cyclic N-Oxides; D005782:Gels; D013213:Starch; D012973:Sodium Hypochlorite; C003959:TEMPO