Consumption of wheat bran modified by autoclaving reduces

fat mass in hamsters

Scott V. Harding1, 3, Harry D. Sapirstein2,*, Todd C. Rideout1, 4, Christopher P. F. Marinangeli1, Arshala

K. M. Dona2, Peter J. H. Jones1,*

1Richardson Centre for Functional Foods and Nutraceuticals and 3Department of Food Science, University of

Manitoba, Winnipeg, Manitoba, R3T 2N2. 3Diabetes and Nutritional Sciences Division, King’s College London,

London, UK, SE1 9NH; 4Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA

*To whom correspondence should be addressed: Prof Harry Sapirstein, Department of Food Science,

University of Manitoba, Email: harry.sapirstein@umanitoba.ca or Prof Peter J. H. Jones, Richardson Centre for

Functional Foods and Nutraceuticals, University of Manitoba, Email: peter.jones@umanitoba.ca

Number of figures: 1

Number of tables: 7

Abbreviations: wheat bran, WB; modified wheat bran, MWB; dual energy X-ray absorptiometry, DXA; total phenolic compounds, TPC; resistant starches, RS; 2,2-diphenyl-1-picrylhydrazyl, DPPH

Supported by Natural Sciences and Engineering Research Council of Canada (PJHJ) and Canadian Wheat

Board (HDS).

Authors’ disclosures: S.V. Harding, H. D. Sapirstein, T. C. Rideout, C. P. F. Marinangeli, A. K. M. Dona, P. J. H.

Jones all have no conflicts of interest to report regarding the work presented in this manuscript.

Keywords: Adiposity, Wheat Bran, Weight Management, Dual Energy X-Ray Absorptiometry

Abstract

Purpose: Here we investigated the contribution that wheat bran modified by autoclaving (MWB) had on

reducing fat accumulation in hamsters fed a hypercholesterolemia- and obesity-inducing diet.

Methods: Male hamsters (n=45) were randomized into 3 groups and fed a hypercholesterolaemia- and

obesity-inducing diet with or without 10% standard wheat bran (WB) or MWB for 28 days. Our outcome

measures included body composition measured by DXA, oxygen consumption and plasma lipids and glucose

concentrations.

Results: Animals fed the MWB diet had lower % fat mass (49.8% vs 53.4%; p = 0.02) and higher % lean body

mass (47.2% vs 44.1%; p = 0.02) compared to controls despite no differences in food intake or weight gain.

Additionally, plasma glucose tended to be lower (6.9 vs 8.5 mmol/L; p < 0.08) in the MWB animals compared

to controls.

Conclusions: Our data suggest that the compositional changes in autoclaved wheat bran, specifically

solubility of phenolic antioxidants and fibre, may have contributed to the lower fat accumulation in our

animals. Further study is needed to determine whether the exact mechanism involved increased lipolysis and

energy utilization from adipose.

Introduction

With considerable lack of clarity as to the definition of a “whole

grain” food, the messages put forward regarding the health

effects of whole grain consumption may be difficult for the

average consumer to interpret. Various jurisdictions have

differing definitions of what constitutes a whole grain food. For

example, the American Association of Cereal Chemists (AACC)

have defined the term “whole grain” as having the same original

composition of endosperm, germ, and bran regardless of whether

the cereal/kernel is whole or reconstituted following milling [1].

Recently, the AACC have added the proviso that a “whole grain

food” must contain at least 8 grams of whole grain per 30 gram

serving [2]. The European Food Safety Authority (EFSA)

recognizes that individual countries within the European Union

(EU) define “whole grain foods” differently (i.e. UK, whole grain

foods must contain ≥51% whole grain ingredients by weight;

Germany, whole grain bread should have at least 90% whole

grain) [3]. The EFSA scientific opinion regarding whole grain

foods helping to prevent chronic diseases does not support the

use of such claims since there is not enough data illustrating a

clear cause and effect relationship [3]. In particular, the EFSA

panel found that defining whole grain foods in the studies

provided to support the health claims an ambiguous task. The

recent scientific position statement by the American Society for

Nutrition (ASN) regarding the consumption of cereal fibres

(whole grain, fibres and bran) on obesity and cardiometabolic

disease risk reduction examines these discrepancies in the

definition of whole grains in more depth [4]. Regardless of the

lack in clarity of the whole grain definition, the number of new

whole grain food products launched worldwide surged 20-fold

between 2000 and 2010 [5].

While the evidence for human health effects is ambiguous for

whole grains in general, increased intakes of foods containing

wheat bran is known to associate with positive health outcomes

in humans. In particular, wheat bran is regularly used as a means

to improve stool regularity and increase fecal bulking [6].

However, the EFSA statement does not support any claims for the

use wheat bran to aid in weight loss or weight maintenance [6].

The ASN scientific statement on cereal fibre or mixtures of whole

grains and bran does support the claim that there is moderate

evidence to suggest that higher consumptions do reduce the risk

of obesity, type 2 diabetes (T2D) and cardiovascular diseases

(CVD) [4]. However, despite epidemiological data supporting

these associations, a mechanistic explanation has not been clearly

shown. In fact, it is not clear whether benefits are tied to

consumption of the entire grain or isolated to bioactive

components contained within a specific fraction.

Wheat endosperm, the source of refined wheat flour, is energy

rich and represents > 80% of grain weight but contains < 10% of

the mineral, vitamin, and dietary fiber content of whole grain [7].

The bran fraction of wheat, generally considered a by-product of

wheat milling, contains the majority of the micronutrients,

dietary fiber and potentially bioactive compounds. In fact, wheat

bran is a significant source of dietary fiber, phenolic compounds

and other phytochemicals which may have health benefits [8-11].

However, despite its compelling nutritive value, wheat bran is

presently predominantly used for animal feed.

What differentiates wheat bran from other cereal brans, such as

oats and barley, is the molecular nature of the fiber or non-starch

polysaccharide (NSP) component. Arabinoxylans or pentosans,

along with the NSP β – glucan, originate in cell walls and

represent the primary dietary fiber source of all cereal grains.

Unlike β–glucans which are the main soluble NSPs of barley and

oats, wheat is distinguished by a relatively low content of β-

glucans and relatively high content of pentosans. The latter are

especially abundant in the bran fraction, comprising about 23-

32% (wt/wt) [12] depending on the genotype source of bran,

where it derives in the milling operation, and content of adhering

starchy endosperm. These fibers including cellulose and inulin,

plus starch and phytic acid make up the majority of the wheat

bran mass, approximately 60%. The balance of the wheat bran

mass is made up of approximately 15% protein, 7% minerals, 5%

lipids, and moisture. While the level of total phenolic compounds

(TPC) in wheat bran is relatively low, as a dietary source it ranks

as major contributor in the human diet since concentrations

range from 2800-5600 mg/kg [13]. The TPC in wheat and bran is

dominated by a single compound, ferulic acid, which comprises

70-95% (wt/wt) of TPC [13].

In human foods, wheat bran is primarily used to boost fiber

content and has been the food industry standard in that regard

for over a century. This use reflects its high level of insoluble

fiber and associated laxative properties which have long been

known as the major health benefit of bran [14]. Several human

studies focusing on the consumption of mixed fiber sources,

including whole wheat, have demonstrated slight to moderate

weight reduction [15-17]. Two of these studies used ready to eat

breakfast cereals while another focused on low glycemic index

foods. While these studies were adequately designed to test the

specific products used, the weight reductions observed were

mainly due to suppression of caloric intake or caloric density of

the diet. Similarly, there are weak in vitro and animal data which

suggest that increased consumption of dietary ferulic acid may

affect fat accumulation in such a way to promote less fat storage

[18,19]. However, there are no human feeding studies which

confirm this hypothesis. Therefore, no direct mechanistic

inferences can be drawn regarding cereal composition and

reduced adiposity.

The primary outcomes of this study were to investigate the effect

of normal (WB) and autoclave-modified wheat bran (MWB)

consumption on 1) adiposity and body composition and 2) blood

lipids in a hamster model of diet induced hypercholesterolemia

and obesity. A previous study demonstrated that autoclaving

significantly increased the water solubility of fiber and

constituent phenolics as well as the antioxidant activity of

extracts [20]. Our two main hypotheses were that autoclave-

modified wheat bran would 1) reduce percentage body fat

accumulation and 2) reduce circulating blood LDL-cholesterol

concentrations, compared to controls consuming calorically

similar diets.

Materials and Methods

Wheat Bran and Modified Wheat Bran. A representative and

commercial sample of milling grade quality Canada Western Red

Spring wheat (~ 1000 kg) was sourced by the Canadian

International Grains Institute (CIGI), Winnipeg, Canada. Wheat

was milled on a Buhler pilot mill to produce bran and flour at an

extraction rate of 76%. Coarse bran was obtained from the

unsifted millstream of the final break roll and separated into

batches, WB and MWB (Table 1). MWB was then produced by

autoclaving at 121 °C with 15 min sterilization at 20 psig (AMSCO

3021, American Sterilizer Co. Pittsburgh, PA). The total autoclave

time was 31 min, and included ~ 5 min at the outset to attain

sterilization conditions, and 10 min after sterilization for drying

at approximately 80°C and -14 psig.

Bran Fractionation. For the purpose of compositional analysis,

WB and MWB were fractionated into water soluble and water-

insoluble components. Typically, 20 g was suspended in

deionized water (1:15 w/v) and the mixture was agitated using a

magnetic stirrer for 18 h at room temperature. Subsequently, the

suspension was filtered to separate insoluble hydrated bran from

soluble material using fiberglass mesh with porosity of ~ 1 mm.

The filtrate was centrifuged at 4,000 x g to obtain a soluble

extract. The latter along with the insoluble residue after filtration

were freeze-dried for subsequent chemical characterization.

Analysis of Bran Composition. Carbohydrate (Table 2) and amino

acid (Table 3) composition analysis was conducted on the

aqueous extract and the fibrous residue for both the WB and

MWB [21,22]. The moisture and protein (N x 5.7) contents of

wheat bran were determined using AACC-International Approved

Methods 44-15A and 46-30, respectively [23,24].

Pentosan Content of Wheat Bran and Extracts. Pentosan content of

wheat bran and freeze-dried water-soluble extracts was

determined in duplicate using a phloroglucinol colorimetric assay

[25]. In this procedure, bran was subjected to pre-hydrolysis

using 0.5 mol/L sulfuric acid to ensure maximal extraction of

pentosans [25]. No pre-hydrolysis was used for aqueous extract

samples.

Total Phenolic Content of Wheat Bran Extracts. Total phenolic

content of freeze-dried water-soluble extracts of wheat bran was

determined in duplicate using a modified version of the Folin-

Ciocalteu method [26,27]. Finely ground sample (30 mg) was

extracted with 100% methanol (1 mL) in microcentrifuge tubes

and vortexed briefly (5 sec) to disperse material. Samples were

extracted for 2 h at room temperature using a RKVSD rotary

mixer (ATR Inc., Laurel, MD) at 20 rpm. Resulting extracts were

centrifuged at 3,180 x g for 10 min. In 2 mL microcentrifuge

tubes, aliquots of the supernatant extract (25 µL) were oxidized

with 0.75 mL of freshly diluted 10% (v/v) Folin-Ciocalteu reagent

and vortexed briefly. After 5 min, the mixture was neutralized

with 0.75 mL of 6% (w/v) sodium carbonate (6 g/100 mL), and

subsequently incubated for 90 min at room temperature in the

dark. Absorbance was measured at 725 nm against a methanol

blank. Ferulic acid was used as the standard for calibration (0 - 3

mM) and results were expressed as ferulic acid equivalents (FAE

µmol/g sample).

DPPH Radical Scavenging Activity of Wheat Bran Extracts. DPPH

radical scavenging activity was performed in duplicate according

to Cheng et al (2006) with some modifications [28]. Finely

ground samples (100 mg) were dispersed in 50% v/v acetone (1

mL) in microcentrifuge tubes and vortexed briefly (5 s) and

subsequently extracted for 2 h at room temperature using a

RKVSD rotary mixer (ATR Inc., Laurel, MD) at 20 rpm. Extracts

were centrifuged at 3,180 x g for 10 min. The absorbance at 515

nm of 0.208 mM DPPH solution for each sample was measured

before sample addition to test tubes. After measuring the initial

absorbance, the supernatant (0.1 ml) for each sample was added

to 3.9 ml of 0.208 mM DPPH solution and vortexed. The solution

was then stored at room temperature for 40 min and the

absorbance at 515 nm was measured again. Trolox standards

were prepared ranging from 0 - 2 mM. All solutions and

incubations were prepared and conducted in the dark. A

standard curve was prepared using trolox and results were

expressed as trolox equivalents (TE µmol/g of sample).

Study Design and Animals. Golden Syrian hamsters (Mesocricetus

auratus; n = 15 per group) were randomized to receive either

control diet alone (Con), formulated in our laboratory (Table 1),

or the same diet with added wheat bran (WB) or modified wheat

bran (MWB). Both normal and modified wheat bran was then

added to the diet in place of corn starch at 10% by weight. The

nutrient composition of the wheat bran is shown in Table 4. This

animal/dietary model is commonly used for cardiometabolic

studies in part because of the similarities in lipid metabolism to

that of humans [29,30].

All animals were then fed the standardized

hypercholesterolemia-inducing diets ad libitum for 28 days with

body weight and food consumption measured every three days

[31]. On day 25, oxygen consumption was measured by indirect

calorimetry using a respiratory gas exchange system for rodents

(MM-100 CWE, Inc. Pennsylvania, USA) and expressed per gram

body weight. On day 28 animals were anesthetized with inhaled

isoflurane and blood sampled by cardiac puncture. Animals were

then killed with an overdose of sodium pentobarbital; body

composition, including total mass, fat mass (FM), lean body mass

(LBM) and bone mineral content (BMC), was determined

immediately by dual emission x-ray absorptiometry (DXA). The

study protocol was approved by the University of Manitoba

Animal Care Committee in accordance to the Canadian Council on

Animal Care Guidelines.

Blood Chemistry. Blood was collected in heparinized tubes and

separated into plasma and packed red blood cells by

centrifugation at 3500 x g for 15 minutes. Plasma glucose,

triglycerides, total cholesterol and HDL cholesterol were

measured using the Vitros Chemistry System 350 (Ortho-Clinical

Diagnostics, Johnson and Johnson, USA).

Statistical Analysis. All outcomes were assessed versus control

animals by student t test using SPSS (Version 20, IBM, Inc.) and P

< 0.05 was considered significant. Pearson correlations were

performed on all animals (n=42) for food intake, final body

weight, % body weight increase, % FM and % LBM with P < 0.05

considered significant. The variance was not homogenous for

cholesterol and non-HDL cholesterol concentrations, therefore

these variables were log transformed for statistical testing but

reported as arithmetic means in this manuscript. All data unless

otherwise indicated are reported as means ± SEM.

Results

Physical Properties of Treatments. Comparing aqueous extracts of

MWB and control bran, the recovery of AOAC 991.43-determined

soluble fiber was 3.2 fold higher, resistant oligosaccharides (RO)

was 2.6-fold higher, inulin was 2.8-fold higher (Table 2). Whereas

there was negligible content of pentosans and β-glucans in water

extracts of control bran, corresponding extracts of MWB

contained 4.4% and 2.5%, respectively (Table 4). Protein

recovery in the aqueous extract was reduced in the MWB

treatment, likely due to thermal denaturation caused by

autoclaving, with the total recovery of individual amino acids

reduced approximately 3-fold compared to WB (Table 3). There

was an increase in phenolic content (74.8 ± 2.1 FAE µmol/g

versus 52.4 ± 1.0 FAE µmol/g; p < 0.05) and DPPH radical

scavenging activity (19.8 ± 0.95 TE, µmol/g versus 3.75 ± 0.18 TE,

µmol/g; p < 0.05) of MWB compared to WB (Figure 1). The

increase in phenolic content and antioxidant activity of aqueous

extracts of the MWB treatment is a reflection of the increase in

pentosan content of the same samples together with ferulic acid

(not measured) which is largely bound to arabinoxylan in wheat

bran as noted previously.

Food Intake, Weight Gain and Oxygen Consumption. No significant

differences were observed amongst groups for initial and final

body weight, % weight gain and food intake during the 28 days of

the experiment (Table 5). Oxygen consumption, measured during

the last week of the experiment, was higher (2.2±0.2 ml/min·g

LBM-1 versus 1.6±0.1 ml/min·g LBM-1; p < 0.05) for the MWB

group compared to control. There were no differences in oxygen

consumption observed between the WB group and control or

MWB. Food intake (g/day) did not correlate with final body

weight, % weight gain, % FM or % LBM.

Body Composition. There were no differences in the body mass,

fat mass or lean mass amongst the treatment groups, as

measured by DXA. However, percent body fat and the lean:fat

mass ratio were lower while percent lean body mass was higher

in MWB animals, compared to controls (Table 6). There were no

differences between the WB animals and either MWB or controls.

Food intake did not correlate with final BW (P=0.31), % BW

increase (P=0.34), % FM (P=0.08) or % LBM (P=0.11).

Blood Biochemistry. Contrary to our hypothesis, no differences

were observed in plasma total cholesterol, non-HDL cholesterol,

HDL cholesterol, triglycerides, glucose, albumin or total protein

between either of the treatment groups or controls (Table 7).

However, there was a trend (p < 0.08) toward lower fasting

glucose in the MWB compared to both WB and controls.

Discussion

Our main finding in this study was a reduction in the % FM in

animals consuming the MWB treatment. Despite no differences

in energy intake across treatment groups, fat accumulation was

lower in MWB treated animals. The consumption of unmodified

WB did not have any effect on adiposity; neither absolute FM nor

% FM was different from control. It is unlikely that the change in

body composition was due to the substitution of wheat bran at

the expense of corn starch in the experimental diet. Replacing the

corn starch with wheat bran reduced the caloric density of the

diet by only 0.22 kcal/g of diet per day. Therefore, the daily

caloric intakes based on mean daily food consumption of each

group would be approximately 35±1.1, 32±1.0 and 33±1.3

kcal/day for the control, WB and MWB, respectively. As there

was no difference in food or caloric intakes and there was no

correlation between food intakes and body composition this

small variation on mean daily caloric intake did not account for

the differences in fat accumulation observed. Therefore, we

speculate that the reduced fat accumulation may have been the

result of either the changes in the carbohydrate properties,

specifically the increased bio-accessibility of fiber and/or

phenolics found in bran.

Modifying the wheat bran in a way that changes the physical

nature of its constituents could possibly modulate the biological

activity of the wheat bran constituents within the digestive tract.

Using autoclave conditions, we have increased the aqueous

recovery of specific NSP (i.e. pentosans, inulin and resistant

oligosaccharides) and total dietary fiber in the aqueous extracts

by approximately three-fold. This increased aqueous recovery

likely increased the exposure of these polysaccharides to the

colonic microflora and facilitated their fermentation. It has been

suggested that the fermentation of NSP in the colon and the

production of short chain fatty acids are strongly linked to the

reduction of adiposity observed with NSP consumption [32,33].

Furthermore, strong evidence from animal studies shows inverse

associations between dietary RS and inulin, and reductions in fat

mass and body weight. In particular, consumption of RS, a form

of soluble or water-dispersible fiber, by rats in a diet induced

obesity study reduced both fat mass and % body fat, with

greatest changes in the mesenteric and subcutaneous adipose

tissue [34]. Similarly, So et al. demonstrated mice consuming

high versus low dietary RS had lower % adiposity despite no

difference in food consumption over 8 weeks [35]. However,

dietary consumption of 25 g NSP and 22 g RS for 4 weeks

increased fecal short chain fatty acid concentrations in healthy

humans, but was not associated with changes in adiposity [36].

Comparable results have also been reported for inulin

supplementation. A study in growing female Sprague-Dawley

rats demonstrated reduced fat mass over 8 weeks of

supplementation with inulin [37]. Similarly, Maurer et al.

reported reduced body weight and fat mass in rats supplemented

with inulin and oligofructose for 6 weeks had compared to

controls and rats fed high protein diets, although in this work

energy consumption was also reduced [38]. However, in both

these studies there was either a decrease in food intake [37] or

energy consumed [38] which accounted for the weight loss. Our

study, while having similar dietary fiber contents but different

physical properties did not result in different food intakes across

groups.

Animal studies examining biological actions of whole grain wheat

and various grain fractions do tend to demonstrate reductions in

adiposity and body composition. For example, Neyrink et al. mice

fed 10% wheat arabinoxylan for 4 weeks were shown to have

reduced body fat compared to controls [33].[31]. However, the

study by Neyrinck and associates examined prebiotic effects of

arabinoxylan supplementation not specifically weight change or

body composition. Several studies using specific oligofructose

supplements report reduced epididymal adipose weight in male

Wistar rats [39-41]. Again, the weight changes and adiposity

observations were secondary as these studies were primarily

designed to examine changes in GLP-1 in response to the

oligofructose feeding.

In addition to fiber, the phenolic content and antioxidant activity

was substantially increased in aqueous MWB extracts, which

would suggest enhanced bio-accessibility or bioavailability of

phenolic compounds, most notably ferulic acid, which is the

predominant factor in wheat antioxidant activity [42]. There is

increasing evidence that foods or beverages with high phenolic

content can modulate physiological and molecular pathways

involved in energy metabolism, adiposity, and obesity [43].

Perhaps most compelling are studies involving phenolic

components or extracts of green tea which is notable for its high

content of catechins. Rodent studies involving experiments

wherein green tea extract or pure catechins were added to an

atherogenic diet have shown significantly reduced body weight

and/or adipose tissue weight [44,45]. The generally favorable

effects of consuming green tea catechins on obesity in mostly

small trials in humans has been recently reviewed [46]. Similar

anti-adiposity outcomes in preclinical trials for other types of

phenolic compounds have been observed for curcumin, the

principal polyphenol in turmeric spice [47] and polyphenol-

enriched (mainly anthocyanidins) extracts of adzuki beans [48].

As noted, the major phenolic compound in wheat bran is ferulic

acid [49] but scant animal data exist on the relationship between

ferulic acid intakes and adiposity [50]. In that study in mice, high

fat diets supplemented with ferulic acid or a related compound,

oryzinol, improved plasma and hepatic lipid profiles, increased

fecal lipid excretion, and lowered final total body mass compared

to controls. However adiposity was not directly measured. Most

of the proposed mechanisms for phenolic intake and reduced

adiposity in this and other studies are still speculative and

require further validation.

We also observed increased oxygen consumption in hamsters

consuming the MWB diet; possibly due to the increased % LBM of

the animals. Alternatively, the increased oxygen consumption

may have been due to direct effects of the MWB in the gut. The

MWB diet treatments could have affected several gastrointestinal

factors directly, including viscosity and digesta transit time, fecal

output and fecal energy content, and microflora diversity. Each

of these factors may individually or in combination affect energy

balance in these animals. Unfortunately, fecal output, caloric

content of the feces and fecal microbial analyses were not

conducted in this study. We do not have a working hypothesis as

to how the MWB might have increased % LBM beyond being the

expected artifact of decreased adiposity. Compositional changes

to the protein (Table 3) of the MWB may have increased the

availability of amino acids and peptides with insulin sensitizing

or mimicking effects in the postprandial period but our study was

not designed to measure those outcomes.

Epidemiological studies have demonstrated a clear inverse

association between whole grain consumption and chronic

disease risk [51-53]. However, data from both population studies

and intervention trials have been inconclusive with some studies

showing whole grain-induced reductions in adiposity while other

showing no effect [54-57]. Unfortunately, little in the way of

evidence exists for a specific mechanism by which increased

whole grain or grain fractions would promote reduced adiposity,

aside from reduced total caloric intake. It has been suggested

that increased bulk of the digesta and changes in the expression

and action of the gut peptides involved the gut-brain axis induce

satiety [58], however, this has not been demonstrated via

intervention trials [59].

A key limitation of our study is the lack of difference observed in

the absolute FM and LBM between the MWB and the controls.

This may be due to high variability in the absolute changes in

body composition between individual hamsters. While the study

was adequately powered for changes in body weight and blood

lipids, there were no available data on changes in body

composition as measured by DXA which could have helped in our

sample size calculation.

In summary, dietary supplementation for 4 weeks with wheat

bran modified by autoclaving resulted in reduced adiposity in

hamsters consuming a hypercholesterolemic and obesity

inducing diet. While the exact underlying mechanisms for these

observations is still not clear, there were significant and

compelling compositional changes in the physicochemical

condition of the bran resulting in increased aqueous recovery of

dietary fiber constituents including phenolic compounds. It

seems plausible that the resulting increase in bio-accessibility or

bioavailability of wheat bran fiber components, including

phenolics, may be involved in the mechanism. Further study is

needed to determine whether the exact mechanism involved

cellular processes such as increased lipolysis and energy

utilization from fat.

Figure 1. Total phenolic content and DPPH radical scavenging activity was determined on aqueous extracts of

untreated and modified wheat bran samples. Both the phenolic content and DPPH scavenging activity was

higher (p < 0.05) in the modified wheat bran extracts compared to the unmodified wheat bran extracts.

Table 1. Nutrient content of wheat bran prior to production of

modified wheat bran.

Nutrient Content

(g/100g)

Fat1 5.0

Carbohydrate2 60.8

Starch 5.2

Sugars 2.5

Fiber 53.1

Protein 12.7

Phytic acid 5.0

Moisture 8.7

Ash 7.5 1Estimated from USDA nutrient data file [7]. 2Further carbohydrate breakdown found in Table 3.

Table 2. Carbohydrate composition (g/100g) of whole, aqueous extract and residues of untreated wheat bran and modified wheat bran.

Whole Bran Aqueous Extract Extract Residue

WB MWB WB MWB WB MWB

Starch 5.2±0.1 4.2±0.2 4.8±0.0 0.4±0.0 - -

Insoluble fiber1 49.4±0.07 48.2±0.21 0.4±0.21 1.6±0.14 72.8±0.35 62.5±0.21

Soluble fiber1 3.7±0.003 4.4±0.21 3.7±0.78 11.7±0.21 2.0±0.14 3.5±0.21

Resistant oligosaccharides2 3.8±0.21 3.8±0.07 8.8±0.14 22.7±0.42 0.1±0.0 0.3±0.07

β-glucan 2.5±0.03 2.6±0.03 nd3 2.5±0.01 2.7±0.007 2.7±0.03

Inulin 1.9±0.13 1.9±0.21 4.6±0.30 13.0±0.28 nd4 nd4

Pentosan 25.7±0.16 25.6±0.25 0.08±0.0 4.42±0.01 - -

Total Dietary Fiber5 56.9 56.4 12.9 35.7 74.9 66.3

Values are means ± SD. 1Insoluble and soluble fiber (AOAC 991.43). 2Resistant oligosaccharides (AOAC 2001.03); not measured by AOAC 991.43. 3Not detected (<0.6%). 4Not detected (<0.5%). 5Sum of insoluble and soluble fiber by AOAC 991.43 plus resistant oligosaccharides. Soluble fiber includes β-glucan and inulin. Untreated wheat bran, WB; autoclaved modified wheat bran, MWB.

Table 3. Amino acid composition of whole, aqueous extract and residues of untreated wheat bran and modified wheat bran.

Whole Bran Aqueous Extract Extract Residue

WB MWB WB MWB WB MWB

Aspartic acid 1.12% 1.11% 1.74% 0.39% 0.96% 1.24%

Threonine 0.50% 0.50% 0.57% 0.16% 0.48% 0.60%

Serine 0.61% 0.61% 0.69% 0.21% 0.56% 0.72%

Glutamic acid 2.55% 2.58% 3.10% 1.65% 2.22% 2.76%

Proline 0.76% 0.78% 1.05% 0.43% 0.66% 0.85%

Glycine 0.85% 0.86% 0.95% 0.37% 0.85% 1.01%

Alanine 0.76% 0.77% 0.98% 0.27% 0.74% 0.92%

Valine 0.64% 0.64% 0.75% 0.19% 0.62% 0.78%

Methionine 0.20% 0.20% 0.21% nd1 0.19% 0.23%

Isoleucine 0.45% 0.45% 0.55% 0.14% 0.42% 0.54%

Leucine 0.88% 0.88% 0.95% 0.24% 0.84% 1.06%

Tyrosine 0.43% 0.43% 0.51% 0.15% 0.38% 0.50%

Phenylalanine 0.56% 0.56% 0.58% 0.21% 0.54% 0.65%

Histidine 0.41% 0.40% 0.43% 0.12% 0.38% 0.48%

Lysine 0.59% 0.53% 0.64% 0.16% 0.52% 0.65%

Arginine 1.13% 1.12% 1.22% 0.41% 1.11% 1.28%

Cystine 0.30% 0.26% 0.55% 0.10% 0.21% 0.31%

Total Amino Acids 12.7% 12.7% 15.4% 5.21% 11. 7% 14.6%

1not detected; analyte level below detection limit. Untreated wheat bran, WB; autoclaved modified wheat bran, MWB.

Table 4. Compositions of control and wheat bran-containing

hypercholesterolemia/adiposity-inducing diets.

Ingredients Con WB/MWB

g/kg

Casein 200.0 200.0

Corn starch 260.0 160.0

Wheat bran/modified wheat bran1 0 100.0

Sucrose 330.3 330.3

Lard-sunflower mix (50:50) 50.0 50.0

Cholesterol 2.5 2.5

Cellulose 100.0 100.0

DL-methionine 5.0 5.0

Mineral mixture2 40.0 40.0

Vitamin mixture3 10.0 10.0

Choline bitartrate 2.0 2.0

BHT4 0.2 0.2 1Nutrient breakdown of WB and MWB are presented in Table 2. 2Vitamin mix

AIN-76A (CA40077; Harlan Teklad, Madison, WI) [60]. 3Mineral mix AIN-93M

(TD94047, modified for hamsters; Harlan Teklad, Madison, WI) [61]. 4Butylated

hydroxytoluene, BHT. Untreated wheat bran, WB; autoclaved modified wheat

bran, MWB.

Table 5. Mean body weight, percent body weight gain and daily food intake of male golden Syrian hamsters fed diets with and without untreated wheat bran and modified wheat bran for 28 d1.

Parameter Con WB MWB

Initial body weight (g) 122.0±2.8 122.7±2.7 122.8±2.5

Final body weight (g) 130.8±3.8 131.3±3.1 131.8±3.8

Body weight increase (%) 7.3±2.2 7.2±2.0 7.4±2.1

Food consumption (g/day) 9.7±0.3 9.8±0.3 10.0±0.4

Oxygen consumption (ml/min·g LBM-1) 1.6±0.1 2.0±0.3 2.2±0.2*

Values are mean ± SEM, n = 13-14. *Different from control, P < 0.05. Untreated wheat bran, WB; autoclaved modified wheat bran, MWB.

Table 6. Mean tissue mass measured by dual-emission X-ray absorptiometry (DXA) of male golden Syrian hamsters fed diets with and without normal and modified wheat bran for 28 d1.

Tissue Mass Con WB MWB

Fat mass (g) 66.4±1.9 63.6±2.4 62.0±2.5

Lean mass (g) 57.8±2.2 60.2±1.6 62.2±2.1

Bone mineral content (g) 3.1±0.07 3.1±0.07 3.1±0.08

Total mass (g) 127.2±3.7 126.7±3.0 127.3±3.8

Percent fat (%) 52.3±0.8 50.0±1.2 48.6±1.1*

Percent lean (%) 44.1±0.8 46.0±1.2 47.2±1.0*

Lean (g)/fat mass (g) 0.87±0.03 0.97±0.04 1.02±0.05*

Values are mean ± SEM, n = 13-14. *Different from control, P < 0.05. Untreated wheat bran, WB; autoclaved modified wheat bran, MWB.

Table 7. Mean plasma biochemistry of male golden Syrian hamsters fed diets with and without normal and modified wheat bran for 28 d1.

Con WB MWB

Glucose 7.83±0.47 8.05±0.54 6.86±0.46

Total cholesterol 7.48±0.44 8.14±0.33 8.49±0.36

HDL cholesterol 3.75±0.10 3.85±0.04 3.86±0.04

Non-HDL cholesterol 3.73±0.37 4.29±0.31 4.63±0.34

Triglycerides 4.10±0.42 3.82±0.32 4.57±0.37

Total protein 64.86±1.66 61.14±1.21 63.43±1.38

Albumin 31.86±0.89 31.43±1.25 32.50±1.17

1Values are mean ± SEM, n = 13-14.

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