title: Effect of kilning on the antioxidant and pro-oxidant activities of pale malts.
abstract: Pale malts were prepared using standard and rapid kilning regimes that differed in the temperature and moisture profiles in the kiln. Samples were taken over the last 9 h of kilning, that is, at 18, 20, 22, 25, and 27 h. Antioxidant activity, assessed by redox potential, scavenging of the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS*+), and ferric reducing/antioxidant power (FRAP), increased at moisture levels below 6.7% for both regimes. The 27 h malt exposed to the rapid regime (moisture content of 4.8%) had a higher activity than the 27 h standard regime sample (moisture content of 4.8%). None of the malts scavenged oxygen. Pro-oxidant activity profiles were different for the malts obtained using each regime and, at 27 h, the rapid procedure gave malt with higher activity. Levels of (+)-catechin and ferulic acid (the most abundant phenolic compounds identified) generally increased as the moisture content of malt fell below 6.7%. Differences in antioxidant and pro-oxidant activities of the 27 h malts are partly attributed to the Maillard reaction, as evidenced by lower L* and higher b* values and higher levels of Maillard-derived flavor compounds, in the sample obtained by the rapid procedure. Levels of lipid-derived flavor compounds were significantly higher after 27 h of kilning using the rapid procedure.
authors.affiliation: School of Food Biosciences, The University of Reading, P.O. Box 226, Reading RG6 6AP, United Kingdom. h.m.woffenden@reading.ac.uk
authors.forename: Helen M
authors.initials: HM
authors.lastname: Woffenden
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Ames
authors.forename: Sachin
authors.initials: S
authors.lastname: Chandra
authors.forename: Monica
authors.initials: M
authors.lastname: Anese
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Nicoli
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D052160:Benzothiazoles; D002392:Catechin / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000032:analysis; D003890:Desiccation; D002523:Edible Grain / Q000737:chemistry*; D005419:Flavonoids; D016166:Free Radical Scavengers; D006358:Hot Temperature; D015416:Maillard Reaction; D016877:Oxidants / Q000032:analysis*; D010084:Oxidation-Reduction; D010636:Phenols / Q000032:analysis; D010936:Plant Extracts / Q000737:chemistry; D011108:Polymers / Q000032:analysis; D013451:Sulfonic Acids; D013997:Time Factors
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D003373:Coumaric Acids; D005419:Flavonoids; D016166:Free Radical Scavengers; D016877:Oxidants; D010636:Phenols; D010936:Plant Extracts; D011108:Polymers; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D002392:Catechin; C004999:ferulic acid