Changes in the content of fructans and arabinoxylans during baking processes of leavened and unleavened breads

Fructans and arabinoxylans (AXs) are prebiotics naturally occurring in cereal grains which have well-known beneficial effects on human health. However, the majority of grains consumed by humans are processed prior to the consumption. The effect of baking on fructan and AX levels has been studied in rye breads, but there is a scarcity of data on the presence of fructans and AXs in wheat breads. Therefore, the aim of this study was to investigate the effect of baking on stability of fructans and total AXs in breads made from both wheat and rye flours. Bread loaves were baked using an automatic bread maker Breville BBM100 (Sydney, Australia). Sugar analysis was performed using high-performance liquid chromatography on a Dionex ICS-3000 unit. This study showed slight loss of total AXs (6–10 %) during preparation processes of leavened, yeast-free and unleavened breads. In contrast, there was 40–60 % degradation in fructan content of leavened, but no significant losses of fructans in unleavened breads. Yeast-free breads had higher contents of both fructans and AXs than leavened breads. Generally, smaller changes in the content of these prebiotics were apparent in wholemeal and rye than in white breads. It seems that differences in the structures of AXs and fructans in cereals, and the presence of yeast play significant role in determining stabilities of these components during baking.     

Enzymatic Reduction of Phytate in Whole Wheat Breads

The presence of phytate in flour may be responsible for reduced bioavailability of iron, magnesium, zinc, and calcium from bread. The effect of various concentrations of commercial phytase or phosphatase added to whole wheat flour-yeast doughs on their phytate and nonphytate phosphorus content has been investigated. By using 2.0% (flour basis) of phytase and 0.11% phosphatase the initial phytate phosphorus concentration of the dough was reduced to 1/8 and 1/12 of its initial values, respectively. Storage of the whole wheat breads for up to 96 hr at room temperature showed further significant reduction of phytate phosphorus. The phytate phosphorus content of yeast leavened whole wheat breads decreased during 2 hours of dough fermentation, baking and the subsequent 48 hours of storage at room temperature from 24 mg/100g dough (dry matter) to 1.7 mg/100g bread (dry matter); the phytate phosphorus continued to decrease and after 96 hours storage it was 0.6 mg/100g bread.     

Reduction of folic acid during baking and implications for mandatory fortification of bread

A pilot scale study designed to quantify the reduction of folic acid during bread baking in Ireland was undertaken. Flour was fortified with different concentrations of folic acid and used to make four different types of commercial bread. The dispersal of folic acid in flour on a pilot scale was variable but better homogeneity would have been achieved in the final bread due to batch size and thorough mixing of the dough. Generally, the heat degradation of folic acid during baking was between 21.9% and 32.1%. Whilst the percentage degradation of folic acid in white pan loaves, white baguettes and brown soda bread were similar the result in wholemeal bread was found to be significantly higher than in other bread types tested. Taking into account all variables affecting folic acid concentration during baking, a concentration of c. 225 μg 100 g^?1 folic acid would be needed in flour to deliver commercial bread in Ireland with an average folic acid content of 120 μg 100 g^?1 in line with Government requirements.     

Comparative study of phytic acid content,in-vitro protein digestibility and amino acid composition of different types of flat breads

Phytic acid content of eight different types of leavened and unleavened flat breads was determined. It was highest in unleavened and non-fermented whole wheat chapati and lowest in the leavened and fermented white wheat flat bread roghni nan. The effect of baking conditions, bread composition and phytic acid content on in-vitro digestibility of protein was measured using a pepsin multienzyme pH stat technique. The amino acids released were separated by ultrafiltration. The rate of protein digestibility of flat bread and amino acid released depended upon the type of flour used, baking conditions, phytic acid content and other antiproteolytic constituents of breads. Leavening and fermentation of breads resulted in an increase of protein digestibility and availability of amino acids. Addition of soya flour increases the protein digestibility of breads whereas millet flour decreases it.     

Properties of yeast free bread produced by supercritical fluid extrusion (SCFX) and vacuum baking

A novel technology, supercritical fluid extrusion (SCFX), allows for continuous production of yeast-free dough leavened via incorporation of supercritical carbon dioxide (SC-CO₂). In this study, an optimum dough formulation, SCFX leavened dough production and baking procedures were developed. A premixed dough was leavened by 1% (feed basis) SC-CO₂ injection in a twin screw extruder at 37 °C. Specific mechanical energy input was 18 kW h/ton. SCFX leavened dough and bread density, moisture content, bake loss, texture profile analysis (TPA) and stress relaxation were evaluated and compared to conventional yeast leavened breads throughout 5-day storage. A combination of vacuum and conventional baking yielded the lowest SCFX leavened bread density of 0.19 g/cm³ and crumb hardness comparable to conventional yeast leavened and commercial products. This approach could be beneficial for a continuous production of consistent ready-to-bake dough and breads having equivalent quality to commercial products but produced in shorter time and without ethanol emission issues.

Industrial relevance

The dough leavening process in conventional bread production is an industrial hurdle for a number of reasons. First, it is very time consuming. Dough leavening through yeast fermentation can take up to eight hours, which is not conducive to high production rates. This long waiting period also means a great deal of storage space is required to produce a large amount of dough. This storage environment must be carefully controlled in terms of temperature, humidity, and air conditions in order to maintain optimal yeast fermentation, which can also be very costly. Finally, the emission of ethanol, a significant byproduct of yeast fermentation, must be controlled according to the EPA clean air act. Expensive catalytic converters must be installed and maintained in commercial bread production facilities.Bread produced by super critical fluid extrusion (SCFX) overcomes these problems. Total dough production time is less than an hour, and with the proper baking equipment, the entire process can be made continuous. This means constant output, less downtime, and none of the costly storage space used for conventional dough proofing. Furthermore, since there is no yeast being used, there is no ethanol being produced. This means no harmful volatile organic emissions and no expensive catalytic converter. Coupled with vacuum baking, this process results in bread with qualities similar to commercially produced bread in significantly less time.     

Influence of malted finger millet and red kidney bean flour on quality characteristics of developed bread

The effects of malted finger millet (MFM) and red kidney bean flour (RKF) substitution on nutritional, sensory, and textural characteristics of yeast leavened bread was investigated in this study. Based on the preliminary studies optimized level of substitution of either MFM or RKF in refined wheat flour in the recipe was fixed at 20 g/100 g of wheat flour. The bread with MFM exhibited better sensorial characteristics and textural attributes in comparison to the RKF incorporated bread. But the addition of RKF showed higher nutritional and mineral composition when compared with the MFM substituted bread. The results further indicated a requirement for optimization of processing conditions to maximize bread quality attributes for better commercial acceptability.     

Increasing the folate content in Egyptian baladi bread using germinated wheat flour

The main objective of this study was to increase the folate content in Egyptian baladi bread using germinated wheat flour (GWF). The effect of germination temperature and drying conditions on the folate content of wheat grains was studied. Wheat flour was substituted with unsieved and sieved GWF at different levels and the effects on folate content and the rheological properties of dough were determined. Germination of wheat grains resulted in a 3- to 4-fold higher folate content depending on the germination temperature. Maximum folate content (61 μg/100 g dry matter (DM)) occurred at 30 °C. Drying did not affect folate content in germinated grains. After replacement with GWF, folate content in both flour and bread increased 1.5- to 4-fold depending on the level of replacement. Rheological properties of dough were adversely affected by increasing replacement level (as determined by farinograph). While the folate content in bread was as high as 66 μg/100 g DM at complete replacement of flour with sieved GWF, the bread was dark and layers were not separated. After replacement of half of the flour with sieved GWF (50 g/100 g), the baladi bread was acceptable with respect to colour and layer separation. The folate content in this bread was 50 μg/100 g DM, compared with 30 μg/100 g DM in bread without GWF (0 g/100 g).     

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.     

Bestimmung der Folsäure-Gehalte von Getreide,Getreideprodukten, Backwaren und Hülsenfrüchten mit Hilfe der Hochleistungsflüssigchromatographie (HPLC)

The folic acid content of grain, cereal products (including beer), bakery products and legumes was determined by means of high-performance liquid chromatography (HPLC). Free folate (monoglutamate forms) and total folate (monoglutamate + polyglutamate forms) were differentiated. Of the grain analysed, rye, with a mean value of 143 μg/100 g, contained more total folate than wheat (mean=91 μg/100 g). The total folate content of bakery products ranged from 14 μg/100 g (whole grain rye bread) to 88 μg/100 g (crispbread). Beer had a very low total folate content (mean=3 μg/100 ml). The mean of the free folate portion was 76.5% in grain and cereal products and 65.6% in bakery products. Of the legumes analysed, beans (mean=128 μg/100 g) had the highest content of total folate, followed by lentils (103 μg/100 g) and peas (57 μg/100 g). The mean value of the free folate portion in legumes (73.1%) was comparable with the values of grain, cereal products and bakery products. In addition to tetrahydrofolic acid (THF), 5-methyl-THF and 5-formyl-THF, pteroylglutamic acid (PteGlu) and 10-formyl-PteGlu were determined in all products (except beer). Their proportion (PteGlu+10-formyl-PteGlu) of the total folate content ranged from 23.5% to 44.4%.     

Effects of baking on protein digestibility of organic spelt products determined by two in vitro digestion methods

Consumption of organic foods is steadily increasing because it is believed to be healthier than conventional foods. This study was designed to investigate protein digestibility of organic spelt bread, biscuit, cookie and muffin in comparison to their corresponding normal wheat products. Three types of fermented bread products namely, yeast leavened, sour and yeast/sour dough were evaluated. Protein digestibility was assessed based on two methods, three-enzyme one-step and two-enzyme two-step digestion in vitro. The one-step digestion method produced results that were comparable with in vivo (rat) methods whereas the two-step digestion method was more reliable in determining differences among the examined wheat products. Organic spelt used in the present study was comparable to common wheat in protein content averaging 15.4 g/100 g dry matter. Slight differences were observed between organic spelt and common wheat products in protein digestibility determined by the two digestion methods. However, significant differences were found among each wheat products. In general, after baking protein digestion was significantly increased. Spelt and common wheat bread products had similar protein digestibility within each type of bread with sour dough breads had the highest protein digestibility. Biscuit, cookie and muffin products possessed lower protein digestibility than breads. In general, variations in protein digestibility due to baking were more noticeable than that found between the two wheats.     

Dough-leavening by Zymomonas mobilis and Its Application to Breadmaking

Among five strains of Zymomonas mobilis strain Z6C had the highest leavening ability in doughs containing either glucose or sucrose. Z6C most efficiently leavened the dough when it contained 5% sucrose, and this leavening ability was twice as much as that of commercial compressed yeast. At the same concentrations of NaCl, the leavening ability of Z6C was reduced more than that of baker's yeast. When comparing baked goods made with yeast, those made with Z6C had similar specific volumes, but Z6C baked goods had slight acidic flavor. Chromatographic analysis of head-space gas of yeast-leavened bread showed that two chemicals appearing in Z6C leavened bread were missing.     

Effect of baking on nutritional properties of starch in organic spelt whole grain products

Consumers of organic spelt food products claim health benefits or sense of well-being from their consumption as opposed to consumption of common wheat products. This study was designed to help clarify the validity of such claims through the evaluation of nutritional properties of starch in a variety of organic spelt products, including breads, biscuits, cookies and muffins, in comparison with their respective common wheat products. Three fermented bread products, namely, yeast leavened, sour and yeast/sour dough were evaluated. Rate and extent of starch digestion were based on the measurement of starch digestion index (SDI) and rapidly available glucose (RAG). The commercial spelt variety used contained approximately eight to ten fold the amount of resistant starch (RS) as compared to common wheat, averaging 3.7% versus 0.4%, and exhibited lower SDI and RAG values. This is the first report to demonstrate high content of RS in spelt. After mixing and fermentation, RS, SDI and RAG reduced, but were still higher in spelt doughs and batters than in those of common wheat. After baking, slight differences were observed in rate and extent of starch digestion between spelt and common wheat baked products. The study showed that differences among baked products were more pronounced than those between spelt and common wheat products.     

Quality parameters and RAPD-PCR differentiation of commercial baker's yeast and hybrid strains

Baker's yeast, Saccharomyces cerevisiae, is a key component in bread baking. Total of 12 commercial baker's yeast and 2 hybrid strains were compared using traditional quality parameters. Total of 5 strains with high leavening power and the 2 hybrid strains were selected and evaluated for their alpha-amylase, maltase, glucoamylase enzymes, and compared using random amplified polymorphic DNA (RAPD). The results revealed that all selected yeast strains have a low level of alpha-amylase and a high level of maltase and glucoamylase enzymes. Meanwhile, the Egyptian yeast strain (EY) had the highest content of alpha-amylase and maltase enzymes followed by the hybrid YH strain. The EY and YH strains have the highest content of glucoamylase enzyme almost with the same level. The RAPD banding patterns showed a wide variation among commercial yeast and hybrid strains. The closely related Egyptian yeast strains (EY and AL) demonstrated close similarity of their genotypes. The 2 hybrid strains were clustered to Turkish and European strains in 1 group. The authors conclude that the identification of strains and hybrids using RAPD technique was useful in determining their genetic relationship. These results can be useful not only for the basic research, but also for the quality control in baking factories.     

Effects of alkylresorcinols on volume and structure of yeast-leavened bread

BACKGROUND: Alkylresorcinols (AR) are amphiphilic phenolic compounds found in high amounts in wheat, durum wheat and rye, with different homologue composition for each cereal. The effect of different amounts of added AR from these cereals on bread volume, height, porosity and microstructure was studied. Breads with added rye bran (with high levels of AR) or acetone‐extracted rye bran (with low levels of AR) were also baked, as well as breads with finely milled forms of each of these brans. RESULTS: Breads with high amounts of added AR, irrespective of AR homologue composition, had a lower volume, a more compact structure and an adverse microstructure compared with breads with no or low levels of added AR. AR were also shown to inhibit the activity of baker's yeast. There was no difference in bread volume and porosity between bread baked with rye bran and acetone‐extracted rye bran or with brans of different particle size. CONCLUSION: Irrespective of homologue composition, AR had a negative effect on wheat bread properties when added in high amounts as purified extracts from wheat, durum wheat and rye. Natural levels of AR in rye bran, however, did not affect the volume and porosity of yeast‐leavened wheat breads. Copyright © 2010 Society of Chemical Industry     

Investigating the einkorn (Triticum monococcum) and common wheat (Triticum aestivum) bread crumb structure with X‐ray microtomography: effects on rheological and sensory properties

Einkorn wheat (Tm, Triticum monococcum L.) has nutritional characteristics that clearly distinguish it from common wheat (Ta, Triticum aestivum L.) although its rheological dough properties may be less‐performing. Therefore, to better understand the potential of Tm for human consumption and food preparation, we compared the quality of bread baked with ancient einkorn and common wheat leavened with brewer's yeast and sourdough. Results showed that Tm had generally higher firmness (21.6 N vs. 10.5 N), and lower (65.6% vs. 71.2%) and less homogeneous porosity than Ta. These results suggest a minor potential in bread‐making regardless of the Tm high total protein content and underline a weaker gluten ability to expand and retain the fermentation gas. The selection of best‐performing einkorn varieties and leavening agents (e.g. fresh sourdough) can lead to bread products with acceptable texture features, meeting consumer demand for organic, natural and ancient products.     

STUDIES ON THE DEVELOPMENT OF PAN BREAD USING RAW WHEAT GERM

Raw wheat germ, known to be high in vitamin E and other phytochemicals, was used to develop pan bread formulations. The raw wheat germ used had protein, fat and ash contents of 27.88, 9.86 and 4.33%, respectively, compared with 11.35, 1.26 and 0.61% for white flour. Reduction in specific loaf volume, due to the inclusion of wheat germ, was significantly restored by using a combination of 30 ppm potassium bromate and 50 ppm ascorbic acid. At levels of 10 and 20% germ incorporation, the use of 3.0% enzyme‐active soy flour significantly improved the specific loaf volume of the test breads. In comparison with white‐flour control bread, panelists did not find any significant differences in any of the sensory attributes of the test bread samples containing up to 10% wheat germ and 0.5% sodium stearoyl‐2‐lactylate (SSL). The minerals, protein and fat content of wheat‐germ‐enriched breads, was superior to the white‐flour control bread. It can be concluded that phytochemical‐enriched pan bread with superior nutritional and sensory qualities can be produced using white flour, 20% wheat germ, 0.5% SSL, 30 ppm potassium bromate and 50 ppm ascorbic acid.     

Acrylamide-asparagine relationship in baked/toasted wheat and rye breads

Acrylamide in baked and toasted wheat and rye bread was studied in relation to levels of asparagine in flour, dough, bread and toasts. Asparagine was consumed during bread preparation resulting in reduced acrylamide content in the products. In wheat bread, 12% of the asparagine initially present in the flour (0.14 g kg(-1)) remained after yeast fermentation and baking; for rye bread, 82% of asparagine remained after sourdough fermentation and baking. Asparagine present in untoasted wheat bread had totally reacted after hard toasting. Toasted wheat and rye bread slices contained 11-161 and 27-205 microg kg(-1) acrylamide, respectively, compared to untoasted wheat and rye bread with <5 and 7-23 microg kg(-1) acrylamide, respectively. The dietary intake of acrylamide from bread (untoasted) of 2 microg day(-1) is relatively low; however, acrylamide exposure from bread increases several fold for people eating toasted bread.     

Optimization of sourdough process for improved sensory profile and texture of wheat bread

The aim of the study was to determine optimum sourdough process conditions for improved flavour and texture of wheat bread. The influence of process conditions and the starter culture on the characteristics of wheat sourdough bread was established by using response surface methodology. Influence of fermentation temperature (16-32 °C), ash content of flour (0.6-1.8 g/100 g), and fermentation time (6-20 h) were considered as independent factors and their effects were studied in sourdough bread fermented with Lactobacillus plantarum, Lactobacillus brevis, Saccharomyces cerevisiae or with a combination of yeast and lactic acid bacteria. Intensity of sensory attributes, specific volume and bread hardness were considered as the main responses. Ash content of flour and fermentation time were the main factors determining the intensity of sensory attributes. The possibility to enhance intensity of overall flavour, aftertaste and roasted flavour without excessive pungent flavour and without reduced fresh flavour in wheat bread containing 20 g sourdough/100 g of wheat dough was demonstrated by choosing e.g. Lb. brevis for a starter and by utilization of high ash content of flour, long fermentation time and reduced temperature. Bread specific volume was improved 0.2-0.5 ml/g and hardness was reduced (after 4 days of storage) up to 260 g by using low ash content of flour and by optimizing fermentation time according to the microbial strain. Lactic acid fermentation had more profound influence on both desired and undesired flavour attributes, as well as textural features of bread in comparison with yeast fermentation.     

Effects of yeast and bran on phytate degradation and minerals in rice bread

ABSTRACT:  Rice bread is a potential alternative to wheat bread for gluten-sensitive individuals. Incorporation of rice bran into bread made from white rice flour adds flavor but also phytic acid, which can reduce the bioavailability of minerals. Breads with varied amounts of defatted bran and yeast were prepared to determine their effects on the phytate and mineral contents of the bread. A completely randomized factorial design was used with bran levels of 3.7%, 7.3%, and 10.5% of the dry ingredients and yeast levels of 1.6%, 3.2%, and 4.7%. Increasing the amount of bran decreased the phytate degradation from 42% at the lowest level of bran to 10% at the highest, and the amount of yeast had no significant effect. The bran contributed substantial amounts of magnesium, iron, and zinc. Breads with the lowest level of bran had phytate-to-zinc molar ratios between 5 and 10, which suggest medium zinc bioavailability. Rice bread is a tasty and nutritious food that is a good dietary source of minerals for people who cannot tolerate wheat bread.     

Impact of sodium chloride on wheat flour dough for yeast-leavened products. II. Baking quality parameters and their relationship

BACKGROUND: The traditional use of sodium chloride (NaCl) fulfills various important rheological, technological and sensory properties in the manufacturing of yeast‐leavened products. However, the use of NaCl in food production has been discussed controversially since a high intake of sodium seems to be associated with hypertension. This study investigates the baking quality parameters of wheat breads containing various levels of NaCl (0–40 g NaCl kg^?1flour). RESULTS: Crumb firmness and rate of bread staling decreased with decreasing NaCl levels. A slight increase in loaf volume was observed based on the increased yeast leavening ability resulting from additional NaCl. Higher crumb retrogradation (measured by differential scanning calorimetry) was observed with low NaCl levels. CONCLUSION: The retrogradation effect is based on the theory that NaCl probably leads to Na⁺ inclusion in starch molecules during storage and thus reduces retrogradation. Further, significant (P?0.05) linear relationships (r ≥ 0.829) between Rheofermentometer results, bread volume and crumb firmness were found, suggesting a predictability of bread quality by measurement of gas release. Copyright © 2011 Society of Chemical Industry