Wheat bran particle size influence on phytochemical extractability and antioxidant properties.
It is unknown if particle size plays a role in extracting health promoting compounds in wheat bran because the extraction of antioxidant and phenolic compounds with particle size reduction has not been well documented. In this study, unmilled whole bran (coarse treatment) was compared to whole bran milled to medium and fine treatments from the same wheat bran. Antioxidant properties (capacity, ability, power), carotenoids and phenolic compounds (phenolic acids, flavonoids, anthocyanins) were measured and compared. The ability of whole bran fractions of differing particle size distributions to inhibit free radicals was assessed using four in vitro models, namely, diphenylpicrylhydrazyl radical-scavenging activity, ferric reducing/antioxidant power (FRAP) assay, oxygen radical absorbance capacity (ORAC), and total antioxidant capacity. Significant differences in phytochemical concentrations and antioxidant properties were observed between whole bran fractions of reduced particle size distribution for some assays. The coarse treatment exhibited significantly higher antioxidant properties compared to the fine treatment; except for the ORAC value, in which coarse was significantly lower. For soluble and bound extractions, the coarse treatment was comparatively higher in total antioxidant capacity (426.72 mg ascorbic acid eq./g) and FRAP value (53.04 μmol FeSO4/g) than bran milled to the finer treatment (314.55 ascorbic acid eq./g and 40.84 μmol FeSO4/g, respectively). Likewise, the fine treatment was higher in phenolic acid (7.36 mg FAE/g), flavonoid (206.74 μg catechin/g), anthocyanin (63.0 μg/g), and carotenoid contents (beta carotene, 14.25 μg/100 g; zeaxanthin, 35.21 μg/100 g; lutein 174.59 μg/100 g) as compared to the coarse treatment. An increase of surface area to mass increased the ORAC value by over 80%. With reduction in particle size, there was a significant increase in extracted anthocyanins, carotenoids and ORAC value. Particle size does effect the extraction of phytochemicals.
Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506, USA.
Lauren Renee
LR
Brewer
Department of Food Technology and Nutrition, Mahasarakham University, Mahasarakham 44000, Thailand.
Jittawan
J
Kubola
Department of Food Technology and Nutrition, Mahasarakham University, Mahasarakham 44000, Thailand.
Sirithon
S
Siriamornpun
USDA-ARS, Center for Grain and Animal Health Research, 1515 College Avenue, Manhattan, KS 66502, USA.
Thomas J
TJ
Herald
Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506, USA. Electronic address: ycshi@ksu.edu.
Yong-Cheng
YC
Shi
D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification*; D004043:Dietary Fiber / Q000032:analysis*; D005511:Food Handling; D010316:Particle Size; D064209:Phytochemicals / Q000737:chemistry / Q000302:isolation & purification*; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification*; D012639:Seeds / Q000737:chemistry; D014908:Triticum / Q000737:chemistry
D000975:Antioxidants; D004043:Dietary Fiber; D064209:Phytochemicals; D010936:Plant Extracts
Antioxidant; Particle size; Phenolic compounds; Wheat bran