Com bran

Fibers and Fiber Sources. Fibers are present ia varyiag amounts ia food iagredients and are also added separately (see Dietary fiber). Some fibers, including beet pulp, apple pomace, citms pulp, wheat bran, com bran, and celluloses are added to improve droppiags (feces) form by providing a matrix that absorbs water. Some calorie-controUed foods iaclude fibers, such as peanut hulls, to provide gastroiatestinal bulk and reduce food iatake. Peanut hulls normally have a high level of aflatoxias. They must be assayed for aflatoxia and levels restricted to prevent food rejection and undesirable effects of mycotoxias. 

Table 17.5 Comparison of phytonutrients and antioxidants of rice bran with com bran, oat bran and wheat bran...

Nutrients (values/100 g) Rice bran Com bran Oat bran Wheat bran... 

Gawalko, E.J., Nowicki, T.W., Babb, J., Tkachuk, R., Wu, S. Comparison of closed-vessel and focused open-vessel microwave dissolution for determination of cadmium, copper, lead, and selenium in wheat, wheat products, com bran, and rice flour by transverse-heated graphite furnace atomic absorption spectrometry. J. AOAC Int. 80, 379-387 (1997)... 

Plant sterols, also called phytosterols, have been reported to include over 250 different sterols and related compounds in various terrestrial and marine materials (Akihisa et al., 1991). Sitosterol, stigmasterol, and campesterol are the commonly consumed plant sterols. The predominant sterol class in vegetable oils is 4-desmethyl sterols. Sitosterol usually contributes more than 50% of desmethyl sterols. The other most significant desmethyl sterols include campesterol, stigmasterol, A5-avenasterol, A7-avenasterol, and A7-stigmastenol. Brassicasterol is a typical sterol for rapeseed and other Cruciferae. Stanol occurs in significant amounts in com bran and fiber oil (Piironen, et al., 2000). 

The bran, gluten, and starch in suspension are now passed over the shakers, vibrating screens of wire gauze, or coarse mesh silk, the coarser portion being first ground and then returned to be likewise passed on the sieve. The starch passes through the sieve while the bran separated is removed, pressed to squeeze out the water, and sold as press feed or dried to form com bran containing 14 per cent, of protein. 

Com bran obtained as a by-product finm the dry-milling of com and yields an oil that contains the above mentioned phytosterols (28). Ifowever, these ferulate phytosterol esters (FPE) are present at very low levels (l.S wt%) in the predominately triaqrlglycerol (TAG)-based oil. Therefore, enrichment of these moieties is desired since thQr can be used as nutraceuticals, commanding a high value in the functional foods market ( 18-20/kg) (29). 

Previous reports 30, 31) have appeared on the use of siqiercritical fluid extraction (SFE) coupled with siqrercritical fluid fractionation (SFF) for the enrichment of these FPE. Carbon dioxide (CO2) and ethanol (EtOH), as a cosolvent, were utilized to fiactionate and eruich the FPE from 1.2S to 14.5 wt% in com bran oil employing a sorbent bed. However, this prior research was performed on an analytical scale. In the present study, SFF technology of com bran oil has been sc ed up using SFE/supercritical fluid chromatogr hy (SFE/SFC). The oil is remov from the com bran 1 utilizing supercritic carbon dioxide (SC-CO2), and then the extract is fiactionated by on-line SFC to obtain a fraction enriched in FPE. 

Three distinct processes were experimentally studied a coupled process for deacidi%ing and enriching the plqrtosterol content of rice bran oil (RBO) by continuous countercurrent colnitmar fiactionation, a scale up of a coupled supercritical fluid extraction (SFE)/ supercritical fluid chromatogr hy (SFC) process for the enrichment of phytosterol in com bran oil, and a unit process involving the snbcritical water extraction of berry substrates. The e q)erimental aspects of the first two processes are described in the literature (36, 37), and will not be repeated here. Research is currently underw to couple the described process below with other unit processes involving both subcritical water and siq)ercritical carbon dioxide. 

The initial fiacdonation experiments were performed utilizing com bran oil and varying amounts of the amino rc l tended silica to check for the possibility of FPE breakthrough. These studies were necessary so that the... 

Before preparative-scale SFE/SFC trials were undertaken, it was necessary to conduct experiments for both the SFE and SFC stages in order to optimize the processes. The SFE runs yielded an average amount of extract equal to 5.8S g. This equaled to an average yield of 3.49 wt% with a relative standard deviation (RSD) of 1.9%. The oil content of the com bran was also determined in triplicate 1 the AOCS Official Method Ac 3-44, which uses petroleum etter as the extraction solvent in a Butt-type extraction apparatus. The organic solvent extraction yielded an average of 3.50 wt% with an RSD of 2.0%, in excellent agreement with the SFE result... 

The sorbent/sorbate ratio of 4 1 was adhered to for these optimization experiments, and preparative-scale SFC was accomplished in three steps followed by a sorbent bed reconditioning as described in the experiment section. The first SFC step removed the majority of the TAG and the phytosterol fat aq l esters. The second step was signed for maximnni FPE eruichment, and the third Auction was run to elute ar r remaining com bran extract fix>m the sorbent bed, preventing extract carryover to subsequent runs. Column reconditioning purged the colirrrm of atqr residual ethanol and com... 

The cumulative mass collected in the fiactions fiom the SFC runs yielded an average of 4.96 g, which represented an 82.7 wt% recovery of the sUuting charge of com bran oil. This is in contrast to earlier research on the analytical-scale SFF of com bran oil, whidi exhibited nearly quantitative mass recovery (50). However, this result is not atypical in preparative scale SFC as evidenced by prior investigators (10,39,40). For example, in the first two studies (10,39) involving the SFC of tocopherols, only parti recovery of the tocoph ls (76 to 87%) was obtained from silica gel. 

Data fiom the prqrarative srale SFE/SFC erqreriments using com bran are shown in Table in. The curmilative mass of the four fiactions averaged 5.75 g, which is practically identical to the previously stated mass recovery of 5.85 g obtained during the preparatory-scale SFE studies. The SFE/SFC mass recovery data is more typical than lower recovered masses noted during the preparatory-scale SFC optimization studies. 

The first collected SFE/SFC fiactions had an average mass recovery of 4.93 g, which represents 85.7% of the total extract. HPLC analyses showed that TG made up approximately 93.6% of these fiactions. This finding corroborated the analytical-scale SFF studies using the 4 1 sorbent/sorbate ratio. In those studies, the first fiactions avera 84.7% of the total extract and TG constituted 94.3% of the fiacdon. The second fiacdon had an average mass recovery of essentially 0.8 g, rqrresendng 13.7% of the total extract FPE comprised almost 13% of the fiacdon. Thus, the FPE were enriched 10-fold from the initial com bran oil content of 1.25%. Free sterols also showed a... 

Fraction 3 had an average mass recovery of 0.03 g, equaling 0.5% of the total extract, and consisted mainly of TG (76%). Free sterols and FPE were also present at 2.1 and 2.7%, reqrectively. The sorbent column reconditioning steps yielded an average mass of 0.002 g, equaling 0.03% of the total extract As in our earlier arralytical-scale com bran SFF sturfy (50), extract carryover from one run to the next did not seem to be problematic. 

Magnesium intake was 1450 mg/subject/day during all periods except when bran supplements were used. Amounts of additional magnesium during these periods were as follows wheat bran, 21.28 com bran, 30.32 and rice bran, 42.13. 

Xylan and Corn Bran. The xylan and com bran fibers were mainly hemlcellulose and contained more complex mixtures of hydrolyzable monosaccharides than the other fiber sources. It was of some Interest to consider the results from the hydrolysis of fecal samples from these diets In an alternate manner. The data were replotted to show monosaccharides recovered as percent of the amount fed for each subject. (Figures 6 and 7). For comparison the composition of the original fiber Is shown on the extreme left as percent dry weight of the fiber. 

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