Free Ferulic Acid Research Articles

Effect of the dose of exogenous fibrolytic enzyme preparations on preingestive fiber hydrolysis, ruminal fermentation, and in vitro digestibility of bermudagrass haylage

Our objectives were to evaluate the effects of the dose rates of 5 Trichoderma reesei and Aspergillus oryzae exogenous fibrolytic enzymes (EFE; 1A, 2A, 11C, 13D, and 15D) on in vitro digestibility, fermentation characteristics, and preingestive hydrolysis of bermudagrass haylage and to identify the optimal dose of each EFE for subsequent in vitro and in vivo studies. In experiment 1, EFE were diluted in citrate-phosphate buffer (pH 6) and applied in quadruplicate in each of 2 runs at 0× (control), 0.5×, 1×, 2×, and 3×; where 1× was the respective manufacturer-recommended dose (2.25, 2.25, 10, 15, and 15g of EFE/kg of dry matter). The suspension was incubated for 24h at 25°C and for a further 24h at 39°C after the addition of ruminal fluid. In experiment 2, a similar approach to that in experiment 1 was used to evaluate simulated preingestive effects, except that sodium azide (0.02% wt/vol) was added to the EFE solution. The suspension was incubated for 24h at 25°C and then 15mL of water was added before filtration to extract water-soluble compounds. For both experiments, data for each enzyme were analyzed separately as a completely randomized block design with a model that included effects of EFE dose, run, and their interaction. In experiment 1, increasing the EFE dose rate nonlinearly increased the DM digestibility of 1A, 2A, 11C, and 13D and the neutral detergent fiber digestibility (NDFD) of 1A, 2A, 11C, and 13D. Optimal doses of 1A, 2A, 11C, 13D, and 15D, as indicated by the greatest increases in NDFD at the lowest dose tested, were 2×, 2×, 1×, 0.5×, and 0.5×, respectively. Increasing the dose rate of 2A, 11C, and 13D nonlinearly increased concentrations of total volatile fatty acids and propionate (mM), decreased their acetate-to-propionate ratios and linearly decreased those of samples treated with 1A and 15D. In experiment 2, increasing the dose rate of each EFE nonlinearly decreased concentrations of netural detergent fiber; also, increasing the dose rate of 1A, 2A, 11C, and 1D nonlinearly increased concentrations of water-soluble carbohydrates and free ferulic acid (μg/g). Application of increasing doses of the EFE increased NDF hydrolysis, NDFD, and ruminal fluid fermentation of bermudagrass haylage, but the optimal dose varied with the EFE.

Abstract 2155: Novel combinations of nano-formulated ferulic acid and aspirin show high potential for chemoprevention of pancreatic cancer

Abstract Pancreatic cancer ranks as the fourth most deadly form of cancer in the United States with about 37,000 deaths each year. This study evaluated the chemopreventive potential of combinations of free and nano-encapsulated mixtures of ferulic acid (FA) and aspirin (ASP) in low doses to human pancreatic cancer cells, MIA PaCa-2 and Panc-1. Cell lines were tested according to published protocols wherein cells were seeded in 96-well microplates and incubated with the unmodified and modified combinations for 72 h and analyzed using MTS cell viability assay method. Apoptosis was measured by flow cytometry. Results demonstrated that free FA (200 µM) and ASP (1 mM) combinations on average reduced cell viability by 60% (P<0.001), and also induced cell apoptosis by 47% (P<0.001) on the two cell lines. However, when individual agents (FA 200 μM; ASP 1mM) were tested, they were virtually ineffective in reducing cell viability, thus indicating an additive/synergistic effect of the two agents in combination. Subsequently, nano-formulations of FA and ASP (nano-FA and nano-ASP) were prepared by encapsulating the agents within solid lipid nanoparticles (SLNs) and tested on the same cell lines. Prior to this, nano-FA and nano-ASP were evaluated for particle sizes and encapsulation efficiencies. Initial particle sizes were 183± 46 nm (nano-FA) and 229±67 nm (nano-ASP), respectively. Furthermore, the encapsulation efficiencies were high for both nano-FA (86%) and nano-ASP (78%). The combination mixture of nano-FA (25 µM) and nano-ASP (25 µM) reduced the cell viability of MIA PaCa-2 and Panc-1 cells by 70% (P<0.001), and also induced cell apoptosis by 30% (P<0.01), thus reducing the dosage of FA by 8-fold and that of ASP by 40-fold to elicit a comparable response as the mixture of the free FA and ASP. Finally, a trans-AM NF-κB transcription factor assay kit was used to help understand the mechanism. Our results demonstrate that nano-FA and nano-ASP combinations significantly down-regulated NF-κB DNA binding activity in MIA PaCa-2 and Panc-1 cells. In conclusion, convincing evidence is provided of the chemopreventive potential of combinations of FA and ASP against pancreatic cancer, especially when formulated within a nanotechnology-based delivery system. Citation Format: Arvind Thakkar, Jeffrey Wang, Sunil Prabhu. Novel combinations of nano-formulated ferulic acid and aspirin show high potential for chemoprevention of pancreatic cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2155. doi:10.1158/1538-7445.AM2014-2155

Impact of wheat bran derived arabinoxylanoligosaccharides and associated ferulic acid on dough and bread properties.

The impact of arabinoxylanoligosaccharides (AXOS) with varying bound or free ferulic acid (FA) content on dough and bread properties was studied in view of their prebiotic and antioxidant properties. AXOS with an FA content of 0.1-1.7% caused an increase in dough firmness with increasing AXOS concentration. AXOS with a high FA content (7.2%), on the contrary, resulted in an increase in dough extensibility and a decrease in resistance to extension, similar to that for free FA, when added in levels up to 2%. Higher levels resulted in unmanageable dough. A limited impact on dough gluten network formation was observed. These results suggest that for highly feruloylated AXOS, the FA-mediated dough softening supersedes the firming effect displayed by the carbohydrate moiety of AXOS. The impact of the different AXOS on bread volume, however, was minimal. Furthermore, AXOS in bread were not engaged in covalent cross-linking and significantly increased its antioxidant capacity.

Study of the Chemical Changes and Evolution of Microbiota During Sourdoughlike Fermentation of Wheat Bran

ABSTRACTSeveral studies have emphasized the possibility of enhancing nutritional properties of cereal by‐products through biotechnological processes. Bran fermentation positively affects the bioavailability of several functional compounds. Moreover, bran fermentation could increase water‐extractable arabinoxylans (WEAX), compounds with positive effects on glucose metabolism and prebiotic properties. This study was aimed at increasing the amount of bran bioactive compounds through a sourdoughlike fermentation process. Wheat bran fermentations were conducted through continuous propagation by back‐slopping of fermented bran (10% inoculum) until a stable microbiota was established, reaching high counts of lactic acid bacteria and yeasts (109 and 107 CFU/g, respectively). At each refreshment step, bacterial strains were isolated, clustered, molecularly analyzed by randomly amplified polymorphic DNA, and identified at the species level by 16S rRNA gene sequencing. Leuconostoc mesenteroides, Lactobacillus brevis, Lactobacillus curvatus, Lactobacillus sakei, Lactobacillus plantarum, Pediococcus pentosaceus, and Pichia fermentans dominated the stable sourdough ecosystem. After fermentation, levels of soluble fiber increased (+30%), and WEAX and free ferulic acid were respectively fourfold and tenfold higher than in raw bran, results probably related to microbial xylan‐degrading activity, whereas phytic acid was completely degraded. These preliminary data suggest that fermented bran could be considered an interesting functional ingredient for nutritional enhancement.

Structural features and feruloylation modulate the fermentability and evolution of antioxidant properties of arabinoxylanoligosaccharides during in vitro fermentation by human gut derived microbiota

In this study, the impact of structural features of (feruloylated) arabinoxylanoligosaccharides (AXOS) on their fermentability and antioxidant properties during in vitro fermentation was investigated. Two AXOS samples with a low average degree of arabinose substitution, specifically differing in average degree of polymerization, and three AXOS samples, specifically differing in ferulic acid (FA) content and appearance (free or bound), were incubated with cultured human colon microbiota. While the impact of average degree of polymerization on AXOS fermentation was small under the conditions used, both bound and free FA inhibited AXOS fermentation. Bound FA probably hinders enzyme activity sterically. Free FA and its microbial metabolites can exert antibacterial effects. Feruloylated AXOS samples exhibited good antioxidant properties, although the antioxidant activity decreased during fermentation as free or released FA was further metabolized.

Release of free ferulic acid and changes in antioxidant properties during the wheat and rye bread making process

Changes in the free ferulic acid (FFA) contents and antioxidant properties during bread making processes were determined. Experimental breads were produced from whole meal and white wheat and rye flours, and fermented using either baker’s yeast or sourdough starter. Sourdough fermented bread contained the highest content of FFA. Release of occurred mainly during dough fermentation. A further increase in the ferulic acid content in the bread crumb and a decrease in the crust was observed. Total antioxidant properties of sourdough bread, defined as the sum of lipophilic and hydrophilic compound activities, were significantly (p<0.05) higher than for yeast bread. Sourdough bread contained more methanol soluble phenolic compounds, proteins, tocochromanols, and oxidized products of fatty acids than yeast bread. The equilibrium between the anti- and pro-oxidative compound contents resulted in similar antioxidant properties for bread using both types of fermentation, and to results observed for the flour used for baking.

Impact of the brown-midrib bm5 mutation on maize lignins.

We have investigated the impact of the brown-midrib bm5 mutation on lignins and on p-coumaric acid and ferulic acid ester-linked to maize (Zea mays L.) cell walls. Lignified stalks or plant aerial parts (without ears) collected at grain maturity were studied in three genetic backgrounds. Relative to the control, bm5 mutants displayed lower levels of lignins and of p-coumarate esters but increased levels of ferulate esters. Thioacidolysis revealed that bm5 lignins display an increased frequency of free-phenolic guaiacyl units. More importantly, thioacidolysis provided unusual amounts of 1,2,2-trithioethyl ethylguaiacol, a marker compound diagnostic for the incorporation of free ferulic acid into lignins by bis 8-O-4 cross-coupling. As the resulting acetal bonding pattern is a chemically labile branch point introduced in maize lignins by the bm5 mutation, this alteration is prone to facilitate the delignification pretreatments used in the cellulose-to-ethanol process.

Improvement of dietary fiber, ferulic acid and calcium contents in pan bread enriched with nejayote food additive from white maize (Zea mays)

Nejayote is the wastewater from the alkaline-cooking of maize and its solids are rich in dietary fiber (45.3%), calcium (5.7%) and ferulic acid (219 mg/100 g). Nejayote solids were used to develop a food additive (NS) consisting of 80% nejayote solids and 20% gluten. NS was incorporated at 3, 6 or 9%, in wheat flour to increase the dietary fiber, calcium, phenolics and antioxidant capacity of breads. The addition of 9% NS did not affect overall baking performance and bread quality but increased dietary fiber up to 54% in composite breads. Moreover, enriched breads contained about 745 times more free ferulic acid and increased approximately 70% their antioxidant capacity. Two slices of bread (64 g) supplemented with 9% of NS provided 29% of the recommended calcium intake. Thus, the NS could be used as a value-added food-ingredient for the preparation of composite bakery-products with improved dietary fiber, calcium, nutraceuticals and antioxidant properties.

Wheat bran with unbound ferulic acid does not alter obesity, insulin resistance or fatty liver in obese rats compared to wheat bran with bound ferulic acid (829.22)

Ferulic acid, the major phenolic acid found in wheat bran, has antioxidant and anti‐inflammatory properties. However, almost all is bound to arabinoxylans and is therefore minimally absorbed. In this study, we determined the effect of wheat bran with bound and unbound (released by a fermentation process) ferulic acid on the development of obesity, insulin resistance and fatty liver in a model of diet‐induced obesity. Rats were fed a high fat diet (35% fat by weight) containing no wheat bran (CON) or 15% wheat bran with either bound (BF; 300 mg/kg diet; 2% free ferulic acid) or unbound (UF; 318 mg/kg diet; 47% free ferulic acid) ferulic acid. After 8 weeks, the BF and UF groups were not different in body weight, epididymal fat pad weight or area under the curve for glucose and insulin tolerance tests compared to the CON group, indicating that 15% wheat bran does not influence adiposity or insulin resistance. However, BF and UF reduced liver lipid levels compared to the CON group, suggesting a decrease in fatty liver. There was no reduction in bodyweight, epididymal fat pad weight, insulin resistance or liver lipids in the UF group compared to the BF group. Additionally, plasma C‐reactive protein, lipopolysaccharide and 24h urinary TBARS did not differ between the UF and BF groups. Wheat bran processed to release ferulic acid offered no apparent advantage relative to unprocessed wheat bran.Grant Funding Source: Supported by Healthy Foods Healthy Lives, Univ. of MN

Combination of modified formulation and bioprocessing techniques as a way to improve nutritional and health potential of bread (1044.13)

Formulation and processing can improve nutritional, functional, and health attributes of foods. In breads, addition of whole wheat (WW) enhances content of dietary fiber, proteins, and non‐nutrients: minerals and antioxidants. Bioaccessibility of these compounds is partial due to cross‐linking to polymers and/or physical entrapment within the complex plant cell wall matrix and can be improved by technological processes. We study the effect of two bioprocessing techniques: A) Enzyme (pre‐ vs in situ treatment), B) dough mixing method (straight vs sponge and dough), in the release of antioxidants (free Ferulic Acid (FA) and Steryl Ferulates), in vitro digestibility, and antioxidant bioaccessibility in WW or Aleurone‐containing WW (AL‐WW) breads. Sponge and‐dough processing and enzyme treatment increases 1.5‐4.0 times the free FA in AL‐WW breads but only in‐situ enzyme treatment enhances free FA (about 1.4 times) in WW breads. Free Steryl Ferulates also increased with both processing methods in AL‐WW breads. Straight dough but not enzyme treatment enhances in vitro digestibility of AL‐WW bread starch fractions while the combination of sponge time and enzyme treatment benefit in vitro digestibility of WW bread. Bioaccessibility of antioxidant compounds (ORAC) is higher in AL‐WW vs WW bread. Thus, nutritional properties and health benefits of bread are influenced by formulation and processing techniques.

Protection of Feruloylated Oligosaccharides from Corn Bran against Oxidative Stress in PC 12 Cells

Feruloylated oligosaccharides (FOs) were prepared by autoclaving corn bran in oxalic acid (0.6%) solution, and their protection effects against oxidative stress in pheochromocytoma cells (PC 12) cells were investigated. The FOs samples, which comprised a mixture of feruloylated mono- and dipentoses with 4.88% bound ferulic acid (FA), as well as xylose, arabinose, galactose, and glucose amounting to 46.43, 40.46, 3.76, and 8.68% of the total sugars, respectively, were prepared by autoclaving the pretreated corn bran in 0.6% oxalic acid and then further separated. Antioxidant activity was tested by 1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) scavenging and oxygen radical absorbance capacity (ORAC) methods. Oxidative stress was induced by H2O2 in PC 12 neuronal cell culture model. The results showed that FOs exhibited higher antioxidant activity than free ferulic acid, with an IC50 value of 11 versus 128 μM for DPPH and an ORAC value of 4.77 versus 2.62 μmol Trolox/μmol. Tetrazolium blue assay showed that the addition of FOs with an FA concentration >50 μM significantly increased cell viability after treatment with H2O2. Flow cytometry analysis showed that the addition of FOs at concentrations of 800, 200, and 50 μM significantly decreased the apoptosis rate at the sub-G0 phase from 37.5 to 12.7, 16.2, and 20.9% (P < 0.01), respectively. FOs also significantly decreased the malonic dialdehyde content and lactate dehydrogenase (LDH) activity, but increased superoxide dismutase activity in PC 12 cells treated with H2O2 and prevented the damage of cellular membranes by decreasing the release of LDH to the cultures. The addition of FA at 800 μM showed an effect similar to that of FOs at 200 μM. Therefore, the FOs prepared from corn bran are potential functional ingredients for protection against oxidative stress.

Production and Antioxidant Properties of the Ferulic Acid-Rich Destarched Wheat Bran Hydrolysate by Feruloyl Esterases from Thermophilic Actinomycetes

Ferulic acid is present at relatively high concentrations in the cell walls of several plants. Agricultural lignocelluloses are now used as bioresources in industry. This study attempted to increase the free ferulic acid content present in lignocellulose by using thermostable esterase produced from thermophilic actinomycetes to hydrolyze ester bonds. Destarched wheat bran was used as a carbon source for the production of esterases from the newly isolated thermophilic actinomycetes species Thermobifida fusca. After 96 h of cultivation, the esterase activity that accumulated in the culture broth was 946.0 U/mL. Two percent of the destarched wheat bran was then hydrolyzed by crude esterase preparation for 16 h. The ferulic acid was accumulated in the culture broth at a concentration of 310.0 M. The hydrolysate had better radical-scavenging ability for both 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical-scavenging ability, as well as reducing power than ferulic acid. These results showed that the ferulic acid-rich destarched wheat bran hydrolysate had good antioxidant properties. It is suggested that this process can be advantageous for the industrial production of antioxidants derived from agricultural bioresources.

Biodegradable ferulic acid-containing poly(anhydride-ester): degradation products with controlled release and sustained antioxidant activity.

Ferulic acid (FA) is an antioxidant and photoprotective agent used in biomedical and cosmetic formulations to prevent skin cancer and senescence. Although FA exhibits numerous health benefits, physicochemical instability leading to decomposition hinders its efficacy. To minimize inherent decomposition, a FA-containing biodegradable polymer was prepared via solution polymerization to chemically incorporate FA into a poly(anhydride-ester). The polymer was characterized using nuclear magnetic resonance and infrared spectroscopies. The molecular weight and thermal properties were also determined. In vitro studies demonstrated that the polymer was hydrolytically degradable, thus providing controlled release of the chemically incorporated bioactive with no detectable decomposition. The polymer degradation products were found to exhibit antioxidant and antibacterial activity comparable to that of free FA, and in vitro cell viability studies demonstrated that the polymer is noncytotoxic toward fibroblasts. This renders the polymer a potential candidate for use as a controlled release system for skin care formulations.

Comparison of postprandial phenolic acid excretions and glucose responses after ingestion of breads with bioprocessed or native rye bran

Rye bran contains a high amount of phenolic acids with potential health promoting effects. However, due to binding to dietary fibre, the phenolic acids are poorly absorbed in human body. We used bioprocessing with enzymes and yeast to release phenolic acids from the fibre complex and studied the effect of bioprocessing on absorption of phenolic acids in healthy humans. White wheat breads fortified with bioprocessed or native rye bran, and wholegrain rye bread and white wheat bread as controls were served to 15 subjects in a randomized order in the cross-over design. Urine was collected at the basal state and over 24 hours in four-, eight-, and twelve-hour periods and analyzed for phenolic acids and their metabolites with gas chromatography. A total of six blood samples were taken over four hours to study the effect of the bread ingestion on postprandial glucose and insulin responses. Bioprocessing of rye bran increased the proportion of free ferulic acid (FA) and soluble arabinoxylan in the bread. Ingestion of the white wheat bread fortified with bioprocessed rye bran increased (p < 0.001) urinary excretion of FA particularly during the first four hours, indicating increased absorption of FA from the small intestine. The postprandial glucose and insulin responses were similar between these breads. Bioprocessing of rye bran did not affect excretion of benzoic, phenylpropionic, and phenylacetic acid metabolites. As a conclusion, bioprocessed rye bran as compared with native rye bran increased absorption of FA from the small intestine, but did not improve postprandial glucose and insulin responses.

Development and Application of a Methodology to Determine Free Ferulic Acid and Ferulic Acid Ester‐Linked to Different Types of Carbohydrates in Cereal Products

ABSTRACTFerulic acid bioavailability is dependent on its form present in food. This necessitates a methodology to quantify different groups of ferulic acid derivatives in food products, especially cereal‐based products. The aim of the proposed methodology is to separate and quantify ferulic acid ester‐linked to mono‐ and/or oligosaccharides (OF), to soluble polysaccharides (SPF), and to insoluble polysaccharides (IPF) as well as in its free form. Development and partial validation of this method, which was widely based on liquid/liquid extraction and precipitation steps, was performed using characterized standard materials isolated from corn bran. As the determination of OF was one of the major goals of this methodology, three different feruloylated mono‐ and oligosaccharides were used for method development and validation. To determine the accuracy of the method, ferulic acid–containing standard materials added to a starch matrix were extracted and separated according to the developed protocol. The separated ferulic acid esters were saponified before ferulic acid was analyzed by reversed phase HPLC. Recovery rates were generally between 70 and 103%, with the lowest recovery rates for SPF and highest recovery rates for IPF and OF. Finally, the applicability of the method to unprocessed and processed wheat bran samples was demonstrated.

Free ferulic acid uptake in lactating cows

Ferulic acid (FRA), a phenolic compound with antioxidant and anticancer activities, naturally occurs in plants as a lignin precursor. Many veins of research have been devoted to releasing FRA from the lignin complex to improve digestibility of ruminant feeds. Thus, the objective of this research was to investigate the transfer of a given dosage of the free form of FRA into the milk of dairy cattle. Six mid- to late-lactation Holstein cows at the Cornell Research Farm (Harford, NY) were given 14-d adaptation to diet and stall position. Ad libitum access to a total mixed ration based on haylage and maize silage (31.1% neutral detergent fiber containing 5.52mg of FRA/g) was provided during the study. A crossover design was implemented so that each cow alternated weekly between FRA-dosed and control. On d 1, jugular cannulas and urine catheters were placed in all cows. On d 2, FRA-dosed cows received a single dosage of 150g of pure FRA powder at 0830 h via their fistula (n=4) or a balling gun for nonfistulated cows (n=2). Plasma, urine, feces, feed, orts, milk, and rumen fluid were sampled intensively for the next 36 h and analyzed for FRA concentration. On d 8, the cows crossed over and the experiment was repeated. When compared with the control, FRA administration did not have an effect on dry matter intake, milk yield, milk fat yield, milk protein yield, somatic cell count, or neutral detergent fiber content of orts and feces. The concentration of FRA in the feces did not change as a result of FRA dosage. As expected, FRA concentration increased dramatically upon FRA dosage and decreased over time until returning to basal levels in rumen fluid (4 h after dosage), plasma (5.5 h after dosage), urine (10 h after dosage), and milk (14 h after dosage). Baseline values for FRA in urine and rumen fluid were variable among cows and had an effect on FRA concentration in FRA-dosed cows. From this study, it is observed that orally ingested FRA can be transported into the milk and that the physiological transfer of FRA occurs from rumen to milk within 6.5 h or the first milking after dosage. Ferulic acid may affect the functionality of milk due to its antioxidant, anticancer, and antibacterial activities. Future research will be required to elucidate whether FRA in milk is bioavailable and bioactive, and to evaluate the complete sensory and microbiological effects of increased FRA and FRA degradation products in milk.

Spring, einkorn and emmer wheat species - potential rich sources of free ferulic acid and other phenolic compounds

&amp;nbsp; Einkorn (Triticum monococcum L., subsp. monococcum), emmer (Triticum dicoccum Schuebl [Schrank], subsp. dicoccum) and spring wheat (Triticum aestivum L.) may be rich in hydrophilic antioxidants, therefore being a potential food source with high nutritional properties. The aim of the present study was to assess the content of free ferulic acid (FFA) and total polyphenols (TP) beneficial for human health in wheat varieties and accessions for breeding and production. Einkorn, emmer and spring wheat varieties were assessed for TP and FFA contents in the precise two-year field experiments. The highest FFA content was determined in emmer wheat varieties and spring cv. Granny. High TP content was characteristic for emmer and spring wheat accessions, however also some einkorn ones were characterised by high levels. Year of cultivation showed a significant impact on FFA contents. &amp;nbsp;

Synthesis of glycosyl ferulate derivatives by amine-promoted glycosylation with regioselective hydrolysis using Novozym 435 and evaluation of their antioxidant properties

Various glycosyl ferulates were efficiently synthesized from 2,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide (TAGB) with amine by amine-promoted glycosylation without using heavy metal. The resulted acetylated glycosyl ferulates with acetoxyl groups at C-2, C-3 and C-4 were regioselectively deacetylated at C-4 and C-6 positions with Novozym 435. Antioxidant abilities of free ferulic acids and its synthetic glycosyl ferulates were evaluated by inhibitory effect on autoxidation of bulk methyl linoleate as well as their radical scavenging activity. The radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) decreased in the order ferulic acid>sinapinic acid≈glycosyl sinapinates≈glycosyl ferulates>p-coumaric acid>glycosyl p-coumarates. In bulk methyl linoleate, the antioxidant activity order against autoxidation was very consistent with the scavenging activity order. The results showed that glycosyl ferulates and sinapinates were effective as well as free carboxylic acid forms.

Antioxidant activities of corn fiber and wheat bran and derived extracts

The antioxidant activity of ground untreated corn fiber and wheat bran against lipid oxidation of rapeseed-fish oil-in-water emulsions was determined with respect to the formation of primary (lipid hydroperoxides) and secondary (propanal and hexanal) oxidation products. Corn fiber inhibited the formation of lipid hydroperoxides secondary products effectively at a concentration of 800 mg/kg emulsion, but wheat bran showed only low antioxidant effects. It was shown that the activity was based on the action of bound hydroxycinnamates like ferulic acid and p-coumaric acid, which was proven by the application of ferulated oligosaccharides (FOm) that showed higher activity than free ferulic acid on a molar basis. Enzymatic treatment with ferulic acid esterases did not increase the antioxidative activity. Extraction of corn fiber and wheat bran with methanol and isopropanol resulted in products which contained only low amounts of free soluble hydroxycinnamates and their marked activity against lipid oxidation and in antioxidant tests (TEAC, DPPH) gave reason for further fractionation. It has been shown that the polyaminconjugates diferuloylputrescine and p-coumaroyl-feruloylputrescine, which are major compounds of the corn fiber methanolic extract, exhibited high antioxidant activity and it can be assumed that they will take part in the antioxidant action of untreated fibers.

Phenolic compounds from hydrolyzed and extracted fiber-rich by-products

Corn fiber and wheat bran are agro-industrial by-products of flour and starch production. It is well known that they contain bound phenolics like ferulic acid and p-coumaric acid. Therefore three different extraction techniques were applied to corn fiber and wheat bran. Alkaline hydrolysis released bound ferulic acid, p-coumaric acid and diferulic acids into its free form. Ferulic acid was found to be the major phenolic compound in corn fiber and wheat bran. Ferulic acid was stable against oxidative damage during alkaline hydrolysis and no major changes of the content were observed at higher NaOH concentrations and reaction times, whereas diferulic acids were only released after treatment with higher concentrated NaOH solutions and after extended reaction time. Acid hydrolysis of corn fiber released soluble ferulated oligosaccharides which are known to possess higher antioxidant potential than monomeric ferulic acid. The methanolic extracts of corn fiber and wheat bran contained only traces of free ferulic acid, but the methanolic corn fiber extract contained high amounts of the polyamine conjugates diferuloylputrescine and p-coumaroyl-feruloylputrescine which are also known as antioxidants. Since they are related to corn fiber oil, an application in lipid-containing food matrices, like emulsions, is reasonable.