Rye Flour Extraction Rate Affects Maillard Reaction Development,Antioxidant Activity,and Acrylamide Formation in Bread Crisps

This report shows the effect of rye flour extraction rate on Maillard reaction, antioxidant activity, and acrylamide formation during toasting of rye bread crisps. Four rye flours with extraction rates of 70, 85, 95, and 100% were tested. Maillard reaction development was studied by measuring browning development, hydroxymethylfurfural (HMF), and glucosilisomaltol (GIM) formation, as well as antioxidant activity. Results showed that HMF and GIM concentrations in toasted bread crisps were higher as the flour extraction rate increases. Antioxidant activity increased during toasting as a consequence of antioxidant Maillard reaction product formation. Acrylamide concentration was clearly affected by free asparagine content of flour, while no effect of dietary fiber and natural antioxidant content of flours had an effect on acrylamide formation. Overall data suggest that the rate of Maillard reaction is higher in whole flours because of their higher free amino acid and protein content.     

Effect of Pea Flours with Different Particle Sizes on Antioxidant Activity in Pan Breads

Pulses are good sources of vitamins and minerals as well as antioxidants. Current literature supports a role for antioxidants in reducing oxidative damage associated with many health disorders, including cardiovascular disease and cancer. The effects of substitution of 10% (w/w) yellow whole or split pea flour (various particle sizes) in white wheat flour (Canadian Wheat Red Spring) on the phenolic and antioxidant activity of the leavened bread were examined. Antioxidant activity was evaluated with four assays, which included 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), metal chelation (MC), and superoxide (SO) radical scavenging assays. The bread samples had reduced DPPH (5–11% scavenging activity) and MC (5–10% scavenging activity) values compared with their respective raw flours. Decreased activity in both the DPPH and MC assays can be attributed to a reduction in the antioxidant capacity in the bread samples owing to dilution with white wheat flour. The MC values for bread samples showed little variability between the yellow whole and split pea flours (8–10% scavenging activity for yellow whole and 9% for split pea flours), which suggests that the antioxidant activity of bread samples is not dramatically affected by the seed coats. Most pea fractions increased the FRAP scavenging activity and decreased the SO scavenging activity values for the bread samples compared with their respective raw flours. We conclude that thermal processing enhanced the antioxidant activity of the bread samples, limiting the dilution effect associated with flour addition during dough make‐up.     

Fermentation Reduces Free Asparagine in Dough and Acrylamide Content in Bread

Free asparagine is an important precursor for acrylamide in cereal products. The content of free asparagine was determined in 11 milling fractions from wheat and rye. Whole grain wheat flour contained 0.5 g/kg and whole grain rye flour 1.1 g/kg. The lowest content was found in sifted wheat flour (0.2 g/kg). Wheat germ had the highest content (4.9 g/kg). Fermentation (baker's yeast or baker's yeast and sourdough) of doughs made with the different milling fractions was performed to investigate whether the content of free asparagine was reduced by this process. In general, most of the asparagine was utilized after 2 hr of fermentation with yeast. Sourdough fermentation, on the other hand, did not reduce the content of free asparagineas efficiently but had a strong negative impact on asparagine utilization by yeast. This indicates that this type of fermentation may result in breads with higher acrylamide content than in breads fermented with yeast only. The effect of fermentation time on acrylamide formation inyeast‐leavened bread was studied in a model system. Doughs (sifted wheat flour with whole grain wheat flour or rye bran) were fermented for a short (15+15 min) or a long time (180+180 min). Compared with short fermentation time, longer fermentation reduced acrylamide content in bread made with whole grain wheat 87%. For breads made with rye bran, the corresponding reduction was 77%. Hence, extensive fermentation with yeast may be one possible way to reduce acrylamide content in bread.     

Literature data may underestimate the actual antioxidant capacity of cereals

Several recent articles have reported a significant antioxidant capacity of cereal products, determined in methanolic and ethanolic extracts. The aim of this work was to conduct an assessment of the antioxidant capacity of cereals using both chemical and in vitro digestive enzymatic extraction of antioxidants. Ferric reducing power (FRAP) and free radical scavenging capacity (DPPH) methods were used to determine the antioxidant capacity in wheat flour, bread, raw and boiled rice, wheat bran, and oat bran. The most efficient antioxidant extraction was achieved by using successively acidic methanol/water (50:50 v/v, pH 2) and acetone/water (70:30 v/v). The antioxidant capacity in these extracts ranged from 1.1 to 4.4 micromol Trolox/g dw. A significant amount of hydrolyzable phenolics with a high antioxidant capacity (from 5 to 108 micromol Trolox/g dw) was found in the residues of this aqueous-organic extraction. The antioxidant capacities of these nonextractable polyphenols are usually ignored in the literature, although they may have an antioxidant role in the gastrointestinal tract, especially after colonic fermentation, and may be fermentated to active metabolites. On the other hand, in vitro digestive enzymatic extracts obtained by enzymatic treatments that mimic conditions in the gastrointestinal tract showed that the amount of antioxidants released by the cereal matrix into the human intestine may be higher than the one that can be expected from measurements in the usual aqueous-organic extracts.     

Phenolic Content,Antioxidant Activity,and Consumer Acceptability of Sorghum Cookies

Cookies were produced from different sorghum flours to determine their potential as vectors of antioxidants. Different sorghum cultivars and their flour extraction rates were evaluated for their effects on phenolic content and antioxidant activity of the cookies. Consumer acceptance of the sorghum cookies was compared with that of wheat flour cookies. For each sorghum cultivar, cookies of 100% extraction rate flours had two to three times more total phenolics compared with those of 70% extraction rate flours, while antioxidant activity was 22–90% higher. Cookies of the condensed tannin sorghum had two to five times more phenolics compared with those of condensed tannin‐free sorghum. Antioxidant activity was 145–227 μMol Trolox equivalents (TE)/g in cookies of condensed tannin sorghum compared with 10–102 μMol TE/g in those of condensed tannin‐free sorghum. The sorghum flours had slightly higher phenolic content and antioxidant activity values than their corresponding cookies. Cookies of the red tannin‐free sorghum flours (PAN 8564/8446) were equally liked as wheat flour cookies, except for texture. However, cookies of condensed tannin sorghum were least accepted compared with wheat flour cookies despite their high antioxidant activity.     

Antioxidants and antioxidant activity of several pigmented rice brans

This study investigated the antioxidant content and activity of phenolic acids, anthocyanins, α-tocopherol and γ-oryzanol in pigmented rice (black and red rice) brans. After methanolic extraction, the DPPH free radical scavenging activity and antioxidant activity were measured. The pigmented rice bran extract had a greater reducing power than a normal rice bran extract from a long grain white rice. All bran extracts were highly effective in inhibiting linoleic acid peroxidation (60-85%). High-performance liquid chromatography (HPLC) analysis of antioxidants in rice bran found that γ-oryzanol (39-63%) and phenolic acids (33-43%) were the major antioxidants in all bran samples, and black rice bran also contained anthocyanins 18-26%. HPLC analysis of anthocyanins showed that pigmented bran was rich in cyanidin-3-glucoside (58-95%). Ferulic acid was the dominant phenolic acid in the rice bran samples. Black rice bran contained gallic, hydroxybenzoic, and protocatechuic acids in higher contents than red rice bran and normal rice bran. Furthermore, the addition of 5% black rice bran to wheat flour used for making bread produced a marked increase in the free radical scavenging and antioxidant activity compared to a control bread.     

Folate content in commercial white and whole wheat sandwich breads

After the U.S. mandate of folic acid fortification of enriched grain products, a report indicated higher than expected fortification. Limited information is available on folic acid in enriched products. We measured the folate content in 92 sandwich breads (46 white breads and 46 whole wheat breads) in Birmingham, Alabama, during 2001-2003. The mean folate content in white bread declined significantly from 2001 to 2002 or 2003, whereas the decline in folate content in whole wheat bread containing enriched flour was not significant. White bread contained significantly more folate than whole wheat bread containing enriched flour in 2001 and 2003. In 2002 and 2003, >40% of breads made of enriched flour contained <115 microg of folate/100 g and >70% contained <160 microg/100 g. These percentages were markedly higher than those in 2001. Our data suggest that folic acid in breads containing enriched flour declined after 2001 and monitoring of fortification may be necessary.     

Effect of Fermentation and Oil Incorporation on the Retention of E Vitamers During Breadmaking

All forms of baking and processing cause a loss of nutrients, including vitamin E, but little is known about these occurrences or if they could be avoided. The objective of this research was to study the incorporation of palm oil and the stability of vitamin E in palm oil during breadmaking. Wheat meal and rye breads were baked with and without the addition of 0, 2, 5, or 8% palm oil. The eight E group vitamers (tocopherols and tocotrienols) were extracted by using accelerated solvent extraction, freeze dried, and then analyzed with normal‐phase HPLC. Compared with the controls, the inclusion of palm oil was found to increase the quantity of all forms of vitamin E in the final baked products. It is concluded that palm oil is effective in increasing the vitamin E content of whole grain bread.     

Studies on rye (Secale cereale L.) lines exhibiting a range of extract viscosities. 2. Rheological and baking characteristics of rye and rye/wheat blends and feeding value for chicks of wholemeals and breads

Five rye lines exhibiting a wide range of extract viscosities were evaluated for the rheological and baking properties of their flours, individually and in blends with hard red spring wheat flour. Commercial cultivars of rye and triticale were included in the study as controls. Extract viscosities of rye flours were higher than those of corresponding wholemeals, indicating shifting of water-extractable arabinoxylan into flour during roller milling. Falling numbers of the rye flours correlated positively with their extract viscosities in the presence (r = 0.73, p < 0.05) or absence (r = 0.65, p < 0.05) of an enzyme inhibitor. Farinograms revealed the weakness of rye and triticale flours compared to wheat flour. Extract viscosities of rye flours were negatively correlated (r = -0.65, p < 0.05) with mixing tolerance index and positively correlated (r = 0.64, p < 0.05) with dough stability, suggesting a positive impact of extract viscosity on dough strength. Extract viscosity was negatively correlated (r = -0.74, p < 0.05) with loaf volume and specific volume (r = -0.73, p < 0.05) and positively correlated (r = 0.73, p < 0.05) with loaf weight of rye/wheat bread. Overall, the results indicated that 30% of flour from high or low extract viscosity rye could be incorporated into rye/wheat breads without seriously compromising bread quality. Inclusion of rye, particularly high extract viscosity rye, in chick diets seriously impeded growth performance and feed efficiency. Part of the arabinoxylan survived bread-making and exerted an effect on chicks, although substantially lower digesta viscosities were observed in chicks fed rye bread diets than in those fed rye wholemeals.     

Effects of Fermentation and Baking of Whole Wheat and Whole Rye Sourdough Breads on Cereal Alkylresorcinols

Alkylresorcinol (AR) content was determined in multiple-stage whole wheat and whole rye flour sours, as well as in whole wheat and whole rye flour doughs and breads. AR content decreased considerably during fermentation and baking. AR content was reduced by 20 and 46%, respectively, at the end of sourdough starter fermentation of whole wheat and whole rye flour sours. AR content, which was 512 and 210 μg/g in whole rye and whole wheat flour doughs, respectively, was 30 and 0 μg/g, respectively, after baking of breads. Synthetic AR added at different levels to doughs was also greatly reduced during fermentation and baking.     

Breadmaking Use of Andean Crops Quinoa,Kañiwa,Kiwicha, and Tarwi

The effect of addition of flours from the highly nutritious Andean crops quinoa (Chenopodium quinoa), kañiwa (Chenopodium pallidicaule), kiwicha (Amaranthus caudatus), and tarwi (Lupinus mutabilis) has been investigated in wheat doughs and fresh bread quality. The thermomechanical profile of wheat doughs and bread quality has been explored by increasing substitution of wheat flour at 0–100% by Andean crop flours. Dough blends were evaluated using the Chopin Mixolab device, whereas bread quality assessment comprised sensory (overall acceptability) and physicochemical (moisture, specific volume, texture, color) determinations in composite breads. In general, no breads with aerated crumb structure could be obtained from 100% Andean crop flours, with the exception of quinoa breads that had overall sensory values about half a completely perfect score, and which were not significantly different from the breads made from a 50:50 blend of wheat and quinoa. Replacement of wheat flour by ≤12.5% (tarwi), 25% (kañiwa), and 50% (kiwicha), respectively, still produced breads with good sensory acceptability but variable color and doughs with acceptable thermomechanical patterns. Partial substitution of wheat flour by Andean crop flours constitutes a viable option to improve the nutritional value of the breads, with acceptable technological performance of dough blends and composite breads.     

Tocopherols and tocotrienols in wheat genotypes in the HEALTHGRAIN Diversity Screen

Tocopherol and tocotrienol compositions were studied in 175 genotypes of different wheat types grown under similar conditions to screen for natural diversity. The main focus was on bread wheats, including 130 and 20 winter and spring types, respectively. The average total content of tocopherols and tocotrienols was 49.4 microg/g of dm, with a range of 27.6-79.7 microg/g of dm, indicating a 2.9-fold variation among genotypes. Beta-tocotrienol and alpha-tocopherol were the major vitamers, and in general there were more tocotrienols than tocopherols. In the early cultivated forms of wheat the proportion of tocotrienols was especially high, at >or=62.5%. In conclusion, there was a large variation in total tocopherol and tocotrienol contents in bread wheats and this, along with the high proportions of tocotrienols in other types of wheat, demonstrates the great genetic potential of genotypes to be exploited by plant breeders.     

Staling Effects When Adding Low Amounts of Normal and Heat‐Treated Barley Flour to a Wheat Bread

The properties of a white wheat bread could be changed by adding normal or heat‐treated barley flour in small amounts (2 and 4%) to a white wheat bread recipe. Differences regarding gelatinization as well as retrogradation properties were found when analyzing the two flours in model systems. The heat‐treated flour was fully gelatinized due to prior time, temperature, and pressure treatment and could therefore absorb larger amounts of water than the other flours. In gelatinized model systems with 40% flour (dwb), the heat‐treated barley flour contained less retrograded amylopectin as compared with normal barley flour after storage for up to 14 days, whereas no differences were found with 20% flour (dwb). However, stored breads showed an increased retrogradation of amylopectin (as measured by differential scanning calorimetry [DSC]) when 2% pretreated barley flour was added as compared with addition of 2% normal barley flour. On the other hand, there were no significant differences at the 4% level. Addition of either of the barley flours resulted in less firm breads during storage as compared with the control breads. Increased water absorption in barley flour and thus increased water content in the breads or different water‐binding capacities of the flour blends could explain these results. The present study indicated that water had a stronger influence on bread firmness than the retrogradation of amylopectin. This conclusion was based on breads with pretreated barley flour being less firm than breads with normal barley flour, although the retrogradation, as determined by DSC, was higher.     

Normal phase high-performance liquid chromatography method for the determination of tocopherols and tocotrienols in cereals

The eight vitamers of vitamin E (alpha-, beta-, gamma-, and delta-tocopherols and -tocotrienols) have different antioxidant and biological activities and have different distributions in foods. Some cereals, especially oat, rye, and barley, are good sources of tocotrienols. A fast procedure for the determination of tocopherols and tocotrienols (tocols) in cereal foods was developed. It involves sample saponification and extraction followed by normal phase high-performance liquid chromatography (HPLC). The results have been compared with those found by direct extraction without saponification. The method is sensitive and selective enough to be tested on a wide variety of cereal samples. The highest tocol levels were found in soft wheat and barley ( approximately 75 mg/kg of dry weight). beta-Tocotrienol is the main vitamer found in hulled and dehulled wheats (from 33 to 43 mg/kg of dry weight), gamma-tocopherol predominates in maize (45 mg/kg of dry weight) ), and alpha-tocotrienol predominates in oat and barley (56 and 40 mg/kg of dry weight, respectively).     

Rapid High‐Performance Liquid Chromatography Determination of Tocopherols and Tocotrienols in Cereals

A rapid normal‐phase high‐performance liquid chromatography (NP‐HPLC) method has been developed for rapid determination of the total content of tocopherols (T) and tocotrienols (T3) in cereals. The new method uses a one‐step extraction followed by NP‐HPLC coupled with a fluorescence detector. The new method provides a baseline separation of the critical peaks of beta‐tocotrienol (β‐T3) and gamma‐tocopherol (γ‐T) within a short time of analysis. The extraction step requires no saponification step or addition of antioxidant. Addition of butylated hydroxytoluene (BHT) had no effect on the stability of vitamin E during sampling. The recovery was 96–100%. The method is demonstrated by successful quantification of vitamin E in barley, wheat, and spelt grains, as well as wheat germ and flours from wheat, spelt, and rye.     

Effect of spelt wheat flour and kernel on bread composition and nutritional characteristics

Spelt wheat seeds (Triticum aestivum subsp. spelta cv. Ostro) were used to obtain white spelt flour (64.5% yield), wholemeal spelt flour (100% yield), and scalded spelt wheat kernels. From these materials, white spelt wheat bread (WSB), wholemeal spelt wheat bread (WMSB), and spelt wheat bread with scalded spelt wheat kernels (SSKB) were made and were compared to the reference white wheat bread (WWB). The spelt wheat flours and breads contained more proteins in comparison to wheat flour and bread. Among the samples the highest rate of starch hydrolysis was noticed in WSB. During the first 30 min of incubation this particular bread was shown to have significantly more (P < 0.05) rapidly digestible starch than the WMSB and later on also more starch than in WWB and SSKB, respectively. The WMSB had the lowest hydrolysis index (HI = 95.7). However, the result did not differ significantly from that in the reference common wheat bread. On the other hand, the most refined spelt wheat flour resulted in a bread product (WSB) that was statistically withdrawn (P < 0.05) as one with the highest HI (112.6).     

Reduced Gelatinization,Hydrolysis, and Digestibility in Whole Wheat Bread in Comparison to White Bread

Wheat, an important crop in North Dakota and the United States, is often used for bread. Health concerns related to chronic diseases have caused a shift toward consumption of whole wheat bread. There has been some indication that the rate and amount of starch digestibility of whole wheat breads may be lower than for their refined flour counterparts. This research investigated the components of whole wheat bread that may reduce starch digestibility and impact nutritional quality. Six formulations of flour were used, which included two refined flours, two whole wheat flours, and two whole wheat flours with added starch. The starch was added to whole wheat flours to increase the starch level to that of the refined flour so that we can determine whether or not the dilution of the starch in whole wheat bread was a factor in lowering the estimated glycemic index (eGI) of whole wheat bread. White and whole wheat flours and breads were evaluated for chemical composition, baking quality by 1 , and eGI by the Englyst assay. Whole wheat breads had significantly (P < 0.05) higher mineral, protein, arabinoxylan, and phenolic acid contents, as well as significantly (P < 0.05) lower eGI. The starch molecular weight was also significantly (P < 0.05) higher for whole wheat and whole wheat + starch breads compared with white breads. The eGIs of refined flour breads were 93.1 and 92.7, whereas the eGIs of whole wheat and whole wheat + starch breads ranged from 83.5 to 85.1. Overall, several factors in the whole wheat bread composition can be found to affect the quality and starch hydrolysis.     

Formation of Enzyme‐Resistant Starch in Bread as Affected by High‐Amylose Wheat Flour Substitutions

High‐amylose wheat flour was used to substitute for normal wheat flour in breadmaking and formation of resistant starch (RS) in bread during storage was determined. Substitution with high‐amylose wheat flour (HAF) decreased peak and final viscosities, breakdown, and setback. Doughs with HAF substitutions were weaker and less elastic, and absorbed more water than those of the normal wheat flour. After baking, RS contents in breads with 10, 30, and 50% HAF substitutions were 1.6, 2.6, and 3.0% (db), respectively, higher than that of the control (0.9%, db). The levels of RS increased gradually during storage for one, three, and five days. With substitutions of 30 and 50% HAF, the total levels of dietary fiber (DF) and RS in bread after five days of storage were 15.5 and 16.8% (db), respectively, as compared to 13.0% (db) in bread from the normal wheat flour. The loaf volumes and appearances of bread crumbs made from HAF substitutions of 10 and 30% were not significantly different from those of the control, whereas the substitution with 50% HAF decreased loaf volume and resulted in inferior appearance of breadcrumbs. The firmness of breadcrumbs increased along with increase in the level of HAF substitutions after baking. During storage, the firmness of breadcrumb with 10% HAF substitutions was higher than that of the control, whereas breads with 30 and 50% HAF substitutions had similar firmness to the control. As a result, HAF might be used to substitute for up to 50% normal wheat flour to make bread with acceptable bread quality and significantly high amount of RS.     

Phytochemical Profile and Antiproliferative Activity of Dough and Bread Fractions Made from Refined and Whole Wheat Flours

Phytochemical profile (phenolic acids, carotenoids, and tocopherols) and antiproliferative properties of bread processing fractions, including the dough, crumb, and upper crust made from refined wheat and whole wheat flours were analyzed for two wheat cultivars. Ferulic acid, lutein, and α‐tocopherol were the predominant phenolic acid, carotenoid, and tocopherol, respectively, extracted from all fractions. The levels of all phytochemicals in whole wheat samples were over eightfold higher than their corresponding refined wheat samples. The concentrations of total phenolic acids (soluble and insoluble bound) were higher in the upper crust of refined (∼60–90%) and whole wheat (∼15–40%) breads than their corresponding dough fractions. However, the dough of whole wheat had higher levels of tocopherols and carotenoids compared with the crumb and upper crust, suggesting that phenolic acids were relatively stable during baking, whereas tocopherols (∼25–80%) and carotenoids (∼20–80%), were partially degraded. The antiproliferative activity of whole wheat bread extracts against HT‐29 cancer cells was weakly correlated with total phenolic acids but showed no correlations with total carotenoid and total tocopherol contents.     

Phytochemical profile of main antioxidants in different fractions of purple and blue wheat, and black barley

Two pigmented wheat genotypes (blue and purple) and two black barley genotypes were fractionated in bran and flour fractions, examined, and compared for their free radical scavenging properties against 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (Trolox equivalent antioxidant capacity, TEAC), ferric reducing antioxidant power (FRAP), total phenolic content (TPC), phenolic acid composition, carotenoid composition, and total anthocyanin content. The results showed that fractionation has a significant influence on the antioxidant properties, TPC, anthocyanin and carotenoid contents, and phenolic acid composition. Bran fractions had the greatest antioxidant activities (1.9-2.3 mmol TEAC/100 g) in all four grain genotypes and were 3-5-fold higher than the respective flour fractions (0.4-0.7 mmol TEAC/100 g). Ferulic acid was the predominant phenolic acid in wheat genotypes (bran fractions) while p-coumaric acid was the predominant phenolic acid in the bran fractions of barley genotypes. High-performance liquid chromatography analysis detected the presence of lutein and zeaxanthin in all fractions with different distribution patterns within the genotypes. The highest contents of anthocyanins were found in the middlings of black barley genotypes or in the shorts of blue and purple wheat. These data suggest the possibility to improve the antioxidant release from cereal-based food through selection of postharvest treatments.