Modification of the rheological behavior of amaranth (Amaranthus hypochondriacus) dough

For people with celiac disease, a lifelong abdication of gluten including-products is necessary to live a life without celiac affected reactions. The production of high-quality bread from gluten free flour is not simple in comparison to gluten including flours such as those derived from wheat (Triticum spp.). The gas binding and crumb structure forming capacity are very low in gluten free batters. They can efficiently be analyzed through the rheological properties of the dough used. The use of acidification in amaranth (Amaranthus hypochondriacus) dough preparation is a possible means of changing the rheological behavior of amaranth in the desired direction. Methods include the use of lactic acid directly, or the fermentation via lactic acid bacteria. Adding up to 20 mL lactic acid/kg flour in amaranth dough preparation led, during oscillation tests, to an increase of the complex shear modulus up to 30% in the range of 0.1 up to 10 Hz. The use of sourdough fermentation decreased the complex shear modulus in the same test up to nearly 60%. In creep recovery tests, the elastic part of amaranth dough decreased from 65.4% without any treatment down to 63.9% by the addition of up to 20 mL lactic acid/kg flour. Sourdough fermentation by Lactobacillus plantarum was able to decrease it to 54%. The acidification showed a significant positive influence on the rheological parameters of amaranth dough only at the higher stress level. In contrast, sourdough fermentation was able to produce doughs with viscosity and elasticity similar to that found in pure wheat flours.     

Starch properties, in vitro digestibility and sensory evaluation of fresh egg pasta produced from oat,teff and wheat flour

Specific dietary requirements, e.g. celiac disease, as well as increased consumer demand for products of high nutritional value, makes the production of pasta from alternative cereals interesting. Raw material characterisation showed that the utilisation of oat and teff flour is beneficial as these ingredients contain higher levels of fibre and mineral composition is superior to that of wheat. Starch properties significantly influence pasta quality and therefore damaged starch levels, amylase activity, pasting properties and gelatinisation temperatures of the flours were investigated. Fresh egg pasta based on wheat, oat and teff flour was produced. Sensory properties of oat spaghetti were found to be very close to that of wheat pasta but improvement of smoothness and aroma is necessary, while teff spaghetti showed reduced sensory quality. An in vitro enzymatic digestion was performed using a dialysis system to mimic the behaviour of pasta as eaten and make predictions on the glycemic index (GI). The predicted GI was highest for wheat pasta, followed by teff and oat. Ultra structure was studied using confocal laser scanning microscopy, allowing the visualisation of differences in starch granule size and shape as well as gelatinisation occurring during the cooking process.     

Pilot scale production of a non-immunogenic soluble gluten by wheat flour transamidation with applications in food processing for celiac-susceptible people

Celiac disease (CD) is an immune-mediated disease triggered by wheat gluten and related prolamins. A lifelong gluten-free (GF) diet is mandatory to normalize the intestinal mucosa. We previously found that transamidation by microbial transglutaminase of gluten was effective in suppressing the gliadin-specific inflammatory response in CD patients without influencing the main technological properties of wheat flour or semolina. In this study, we produced on a pilot scale a soluble form of transamidated gluten (soluble protein fraction, spf), characterised by a high protein content (88 mg/ml), while native gluten was dramatically reduced (32 ± 2 ppm; R5-ELISA). Using HLA-DQ8 transgenic mice as a CD model, we found suppression of interferon-γ secretion in gliadin-specific CD4⁺ T cells challenged with spf-primed dendritic cells. In terms of functional properties, spf showed both solubility and emulsifying activity values within the range of commercial soluble glutens. Notably, dough prepared by mixing rice flour with spf could leaven. After baking, blended rice bread had a higher specific volume (2.9 ± 0.1) than control rice bread (2.0 ± 0.1) and acquired wheat-like sensory features. Taken together, our results highlighted the technological value of transamidated soluble gluten to improve both nutritional and sensory parameters of GF food.     

Effect of immature wheat flour on nutritional and technological quality of sourdough bread

In this study, the effect of immature wheat flour (IWF) on the fermentation activity of lactic acid bacteria (LAB) and on the nutritional quality properties of bread were evaluated. IWF was added in the as the ratio of 10g/100g in sourdough fermentation medium, and the fermentation activity (total LAB, pH, titration acidity (TA), and total reducing sugar (TRS)) of LAB cultures was monitored. Additionally, some physical quality characteristics (specific volume, texture profile and colour value), estimated glycaemic index (eGI), rapidly digestible starch (RDS), slowly digestible starch (SDS), and the total dietary fibre content of sourdough bread were determined. According to the statistical test, it was revealed that the IWF addition stimulated LAB growth and increased their fermentation activity. The pH of the fermentation medium decreased from 6.57 to 3.50, and TA raised from 0.13% to 1.2% in 48 h. The highest TRS content was determined in IWF enriched sourdough samples, and as a result of this, the eGI of sourdough bread increased. Compared to the control sample, the SDS and total dietary fibre content were higher in IWF added sourdough bread, and a positive correlation was noted between these two components. IWF utilisation of sourdough bread formulation increased the hardness value by nearly 50%.     

Evidence for different supramolecular arrangements in pasta from durum wheat (Triticum durum) and einkorn (Triticum monococcum) flours

The effects of the replacement of einkorn flour on pasta proteins aggregation were studied by sodium dodecyl sulfate polyacrylamide gel electrophoresis and size exclusion high performance chromatography. Pasta was produced replacing durum wheat semolina with an increasing amount of einkorn flour (30, 50 and 100%). The polymeric protein structure of flours and related pasta and pasta mixture was determined by protein subunits composition and size of polymeric proteins. The unextractability of polymeric protein was related to the unextractable protein fraction and to the determination of –SH/-SS groups. Durum wheat semolina and einkorn flours increased their unextractable and polymeric fractions during pasta processing. The unexpected results derived from the areas of unextractable fractions and total and large unextractable polymeric fractions of 70/30 semolina/einkorn pasta mixture that were lower than those of 50/50 semolina/einkorn pasta mixture. Although the semolina flour contained more gluten proteins than einkorn flour, a higher aggregation was registered for 50/50 semolina/einkorn flour pasta. These results suggested that a different assessment of gluten network occurred in pasta mixture and it was regulated by a self-assembling machine influenced by nature of HMW-GS. The 50/50 semolina/einkorn pasta mixture determined a supramolecular structure in the developing of its network architecture.     

Influence of particle size and blend composition on quality of wheat semolina-pearl millet pasta

Effect of particle size and blend composition (wheat semolina: pearl millet flour) on quality of pasta were investigated in this study. Initially, the pasta was prepared from 100% pearl millet flour of different particle sizes (241–780 μm). Observation indicated that it was not possible to make pasta from 100% pearl millet flour as these disintegrated after cooking. Particle sizes of pearl millet flour showed significant effect on nutritional and cooking quality of pearl millet pasta. Pasta from pearl millet flour of particle size 425 μm had least cooking loss, high protein, iron and zinc contents. Further, with increase in the level of pearl millet flour in the blend composition, protein, ash and cooking loss of pasta increased whereas hardness, cohesiveness, springiness, gumminess and chewiness showed decreasing trend. Blend composition (wheat semolina: pearl millet flour) in the ratio of 70:30 was found to be satisfactory for making pasta with desirable quality characteristics like cooking loss (<8%), protein content (>10%), ash content (<0.7%), colour and texture. However, with the objective of maximum incorporation of pearl millet flour in the final product, a blend composition of 50:50 could be used to make pasta with acceptable quality.     

Suitability of enzymatic hydrolyzates of extracted gluten from fresh pasta by-product used as bread improvers

Gluten extracted from fresh pasta by-products (PG) was enzymatically hydrolyzed by two different commercial proteases (Alcalase 2.4 L and Pancreatin) to different degrees of hydrolysis (DH 2.0, 4.0 and 8.0%). Commercial gluten (CG) was used as reference. The evaluation of functional properties of hydrolyzates from pasta gluten (PGH) and commercial gluten (CGH) showed that Pancreatin hydrolyzates had the highest emulsifying capacities. Regarding the foaming activity, all hydrolyzates performed better than unhydrolyzed gluten. PGH and CGH were added to wheat flour (1%) and their effects on dough rheology were studied. Most hydrolyzates with DH 8% increased dough thermal stability and elasticity during mixing, accelerated the denaturation rate of the protein network, and delayed the gelatinization speed of starch as the temperature increased. Texture profiles and specific volumes of breads from low quality wheat flour with added Pancreatin hydrolyzates (DH 8%) were comparable to those of breads from high quality flour. This showed the potential suitability of PGH and CGH as bread improvers.     

Improvement of zein dough characteristics using dilute organic acids

The replacement of gluten in dough products poses a major challenge. Preparing zein doughs in dilute acetic acid and lactic acid, such as produced during sourdough fermentation, was investigated. Increasing acid concentrations (0.7, 1.3 and 5.4% [v/v]) increased zein extensibility and reduced the stress and related parameters. Preparation of zein-maize starch/-rice doughs in dilute organic acids improved dough properties to the extent that the doughs could hold air and be inflated into a bubble by Alveography. Further, they exhibited similar Stability (P), Distensibility and deformation energy (W) to wheat flour dough. Confocal laser scanning microscopy revealed an ordered linear fibril network in zein and zein-rice flour doughs prepared in the dilute acids, which became uniform with increasing acid concentration. SDS-PAGE showed that the acids did not hydrolyse or polymerise the zein. FTIR indicated that the acidic conditions slightly increased the proportion of α-helical conformation in the zein doughs, possibly as a result of deamination. This conformational change may be responsible for the considerably improved zein dough properties. Zein doughs prepared in dilute organic acids show potential as a gluten replacement in gluten-free formulations.     

Functional Properties of Gluten-Free Pasta Produced from Amaranth, Quinoa and Buckwheat

The use of amaranth, quinoa and buckwheat for the production of gluten-free pasta was investigated in the present study. The aim of the work was to produce pasta of good textural quality, in particular, low cooking loss, optimal cooking weight and texture firmness. The results demonstrated that pasta produced from amaranth had decreased texture firmness and cooking time, while pasta from quinoa mainly showed increased cooking loss. In buckwheat pasta the least negative effects were observed. By combination of all three raw materials to one flour blend in the ratio of 60% buckwheat, 20% amaranth and 20% quinoa, dough matrix was improved. After decreasing dough moisture to 30%, addition of an increased amount of egg white powder of 6% and addition of 1.2% emulsifier (distilled monoglycerides) texture firmness as well as cooking quality of gluten-free pasta produced from such a flour blend reached acceptable values comparable to wheat pasta.     

豆渣馒头加工工艺研究

研究了豆腐渣粉、谷朊粉、酵母添加量对馒头感官品质和质构特性(TPA)的影响,通过单因素和正交试验确定豆渣馒头的最佳工艺条件,并采用环境扫描电镜研究豆渣馒头的微观结构.结果表明:小麦面粉85 g、豆腐渣粉15 g、谷朊粉1g、活性干酵母0.6g、发酵时间120 min时制作的豆渣馒头具有良好的品质和口感.电镜分析显示,豆...     

Influence of redox-reactions catalysed by homo- and hetero-fermentative lactobacilli on gluten in wheat sourdoughs

The effect of redox reactions catalysed by lactobacilli on properties of wheat gluten was followed during sourdough fermentations. Thiol levels in doughs remained high in doughs fermented with Lactobacillus sanfranciscensis or in chemically acidified doughs to which 10 μmol g^–1 glutathione were added. In chemically acidified doughs or sourdoughs fermented with L. sakei or L. perolens, the thiol levels decreased during fermentation. Thiol-groups in gluten proteins were estimated by RP-HPLC separation of DAC-maleimide-labeled, propanol-soluble proteins extracted from wheat doughs. An increase of the SH groups in gluten proteins was observed in protein fractions from sourdoughs fermented with L. sanfranciscensis but not from chemically acidified doughs. A glutathione-reductase was expressed in L. sanfranciscensis and during its growth in sourdough resulted in the reduction of extracellular GSSG to GSH. It was concluded that in addition to the pH-dependent activity of cereal proteases, redox reactions catalysed by lactobacilli determine gluten quality during sourdough fermentations. The formation of thiols by L. sanfranciscensis interferes with gluten polymerisation. Due to differences in their central carbon metabolism, homo- or facultative hetero-fermentative lactobacilli have opposite effects on redox-reactions in wheat doughs.     

Nutritional properties and ultra-structure of commercial gluten free flours from different botanical sources compared to wheat flours

Coeliac patients suffer from an immune mediated disease, triggered by the ingestion of a protein composite (gluten) found in wheat, rye and barley. Consequently, there is a need for products such as bread or pasta, made from alternative cereal grains or pseudocereals. A fair proportion of the gluten free products currently on the market are nutritionally inadequate. Hence, it was the aim of this study to investigate the nutrient composition of seven commonly used commercial gluten free flours (oat, rice, sorghum, maize, teff, buckwheat and quinoa) and compare them to wheat and wholemeal wheat flour. In addition to the levels of all major compounds, also mineral composition, fatty acid profile, phytate, polyphenols and folate content were determined. Furthermore, properties of carbohydrates were studied in greater detail, looking at total and damaged starch levels; total, soluble and insoluble dietary fibre content as well as amylose/amylopectin ratio. Proteins were further investigated by means of capillary electrophoreses. Additionally, the ultra-structure of these materials was explored using scanning electron microscopy. The results show that maize and rice flour are poor regarding their nutritional value (low protein, fibre, folate contents). In contrast, teff as well as the pseudocereals quinoa and buckwheat show a favourable fatty acid composition and are high in protein and folate. In particular, quinoa and teff are characterised by high fibre content and are high in calcium, magnesium and iron. Therefore these flours represent nutrient-dense raw materials for the production of gluten free foods.     

Improvements in the qualities of gluten-free bread after using a protease obtained from Aspergillus oryzae

From a nutritional perspective, rice flour is one of the most valuable flours and it is suitable for preparing food for people suffering from wheat allergy. However, bread made from rice flour is very difficult to bake because it lacks gluten. We found that pre-fermenting of rice flour using Aspergillus oryzae facilitated a better formulation of gluten-free rice bread. Bread swelling was remarkably improved with a longer pre-fermenting period at 55 °C. The specific loaf volume (SLV) without polymeric thickeners after a 12 h fermentation was approximately 2.2-fold (2.98 ml/g) higher than that after 0 h (1.36 ml/g). An enzymatic assay of the batter indicated that protease activity during the pre-fermentation period increased from 0.38 to 1.44 U/ml and this activity correlated with bread swelling. Furthermore, a commercial protease from A. oryzae also produced similar results with an adequate SLV of 3.03 ml/g. Rheological analysis showed that batter treated with protease had an increased batter viscosity and decreased flour settling behavior because of the aggregation of flour particle after partial cleavage of storage proteins. These results indicated that the improved SLV was mainly because of an A. oryzae protease, which affected the batter rheology thereby improving gas retention before baking.     

Effect of different breadmaking methods on thiamine,riboflavin and pyridoxine contents of wheat bread

Whole wheat bread represents an important source of dietary fibre and micronutrients such as minerals and vitamins (B1, B2, B6). Thus it is important to control losses of vitamins during milling and breadmaking. The classical (yeast) breadmaking process is a relatively severe, leading to a 48% loss of thiamine in white bread. Longer fermentation times (white bread) led to higher thiamine concentrations (2.5 μg/g) than shorter fermentations (1.4 μg/g). In whole wheat bread, separate yeast or sourdough fermentations maintained vitamin B1 levels close to that of the original flour (5.5 μg/g). Whole wheat breadmaking with yeast (from kneading to final bread), in long fermentations, resulted in a 30% enrichment in riboflavin. The pyridoxine concentration of whole wheat flour is 5-fold higher than white flour, but classical fermentations resulted in a severe depletion in pyridoxine (−47%). The use of mixed fermentation conditions (yeast plus sourdough) had no synergistic impact on B vitamin levels. The classical breadmaking protocol is time-saving but does not result in maximal vitamin retention. Highest levels of B vitamins were achieved by long yeast fermentations.     

Improving the quality of nutrient-rich Teff (Eragrostis tef) breads by combination of enzymes in straight dough and sourdough breadmaking

The growing interest in the benefits of wholegrain products has resulted in the development of baked products incorporating less utilised and ancient grains such as, millet, quinoa, sorghum and teff. However, addition of wholegrains can have detrimental effects on textural and sensory bread product qualities.Enzymes can be utilised to improve breadmaking performance of wholegrain flours, which do not possess the same visco-elastic properties as refined wheat flour, in order to produce a healthy and consumer acceptable cereal product.The effects of Teff grain on dough and bread quality, selected nutritional properties and the impact of enzymes on physical, textural and sensory properties of straight dough and sourdough Teff breads were investigated.Teff breads were prepared with the replacement of white wheat flour with Teff flour at various levels (0%, 10%, 20%, and 30%) using straight dough and sourdough breadmaking. Different combinations of enzymes, including xylanase and amylase (X + A), amylase and glucose oxidase (A + GO), glucose oxidase and xylanase (GO + X), lipase and amylase (L + A) were used to improve the quality of the highest level Teff breads. A number of physical, textural and sensory properties of the finished products were studied. The nutritional value of breads was determined by measuring chemical composition for iron, total antioxidant capacity, protein, fibre and fat. The obtained results were used to estimates intakes of nutrients and to compare them with DRIs.The incorporation of Teff significantly (P < 0.05) improved dietary iron levels as 30% Teff breads contained more than double the amount of iron when compared to corresponding wheat bread (6 mg/100 g v 2 mg/100 g). Addition of Teff also significantly (P < 0.05) improved total antioxidant capacity from 1.4 mM TEAC/100 g to 2.4 mM TEAC/100 g. It was estimated that an average daily allowance of 200 g of Teff enriched bread would contribute to DRIs in the range of 42-81% for iron in females, 72-138% for iron in males; 38-39% for protein in males, 46-48% for protein in females; and 47-50% of fibre in adults.The major challenge was encountered in producing the highest level of Teff bread with good textural and sensory attributes. Increasing the level of Teff significantly (P < 0.05) increased dough development time, degree of softening, crumb firmness and bitter flavour whilst decreasing the dough stability, specific loaf volume and overall acceptability of the bread. Teff breads produced with the addition of enzyme combinations showed significant improvements (P < 0.05) in terms of loaf volume, crumb firmness, crumb structure, flavour and overall acceptability in both straight dough and sourdough breadmaking.     

Characterisation of gluten-free pasta through conventional and innovative methods: Evaluation of the uncooked products

Formation of a gluten protein network is fundamental for the texture and the overall quality of pasta. Replacement of the gluten network in gluten-free pasta is a major technological challenge, and the conventional technological processes have to be adapted to non-gluten formulations. The wide variety of raw materials and technologies used in the production of commercial gluten-free pasta stems from the – still on-going – search for solutions to these problems. The aim of this study was to evaluate the characteristics of different commercial gluten-free spaghetti currently available on the market, focusing on starch and protein organisation. Taking into account the chemical and biochemical properties of the samples, and their relationships to the physical characteristics of these products we looked at how some molecular properties relate to the final structure and quality of gluten-free pasta. Phenomena related to starch retrogradation were found to play a central role for the final texture of the products. At the same time, the origin of proteins included in the formulation was found to govern the protein–protein interactions, especially in those samples including proteins from different vegetable sources.     

Evaluation of wheat and emmer varieties for artisanal baking,pasta making,and sensory quality

Identifying varieties best suited to local food systems requires a comprehensive understanding of varietal performance from field to fork. After conducting four years of field trials to test which varieties of ancient, heritage, and modern wheat grow best on organically managed land, we screened a subset of varieties for bread, pastry, pasta, and cooked grain quality. The varieties evaluated were three lines of emmer (T. turgidum L. ssp. dicoccum Schrank ex Schübl) and eleven lines of common wheat (Triticum aestivum L.), including two modern soft wheat varieties, four soft heritage wheat varieties, four hard modern wheat varieties, and one hard heritage wheat variety. A diverse group of bakers, chefs, researchers, and consumers compared varieties for qualities of interest to regional markets. Participants assessed differences in sensory profiles, pasta making ability, and baking quality for sourdough, matzah crackers, yeast bread, and shortbread cookies. In addition to detecting significant differences among varieties for pasta, sourdough, and pastry quality, participants documented variation in texture and flavor for the evaluated products. By demonstrating which varieties perform best in the field, in the bakery, and on our taste buds, these results can support recommendations that strengthen the revival of local grain economies.     

Glycemic index and firming kinetics of partially baked frozen gluten-free bread with sourdough

Gluten-free bread often has low nutritive value, high glycemic index (GI) and short shelf-life. The aim of this research was to investigate the influence of sourdough addition on GI, quality parameters and firming kinetics of gluten-free bread produced by partially baked frozen technology. Sourdough was fermented with a commercial starter of Lactobacillus fermentum and added to bread batter at four levels (7.5; 15; 22.5 or 30%). We determined biochemical characteristics of the sourdough and bread chemical composition, glycemic index in vivo, physical properties and firming kinetics after final rebaking. All breads were enriched with inulin and were high in fiber (>6 g/100 g). Control bread that was prepared without sourdough had medium GI (68). Sourdough addition decreased bread GI. However, only breads with 15 and 22.5% of sourdough had low GI. Moreover, addition of 15 and 22.5% of sourdough had positively affected the quality parameters of partially baked frozen bread: specific volume increased, crumb firmness decreased and firming was delayed. In conclusion, the combined application of sourdough and partially baked frozen technology can decrease glycemic index, improve quality and shelf-life of gluten-free bread. Such breads can be recommended as a part of well balanced gluten-free diet.     

In vitro digestion kinetics and bioaccessibility of starch in cereal food products

The study of starch digestion in cereal-based products is essential since the extent and rate of hydrolysis affects the glycemic index associated with several food-related diseases. Besides, a unique matrix is usually studied and many variations of in vitro techniques (e.g. enzymes, pH, food:enzymes ratio) are selected, then comparison of results became difficult. The recently published INFOGEST in vitro static method with international consensus (Minekus et al., 2014) was applied to several cereal-based products to address whether it is suitable for analysis of starch hydrolysis kinetics. Bread, pasta and cookies were selected taking into account the analysis of different cereal matrixes, including gluten-free products. White bread presented the highest in vitro starch hydrolysis (87%) showing significant differences compared to gluten-free bread (76.5%). Refined flour sheeted pasta (72.6%), whole-wheat extruded pasta (92.0%) and gluten-free pasta (54.3%) showed differences in the extent and rate of hydrolysis. Cookie samples presented the lowest starch hydrolysis (∼45%). The starch availability was estimated by the dializability method, which measures the maltose equivalents dialyzed after simulating digestion. Starch dializability was 35%, 25% and 15% on average for bread, pasta and cookie samples respectively, with positive correlation with rapidly digested starch. The tested in vitro method allowed discriminating the effect of different processing techniques, product types and formulation of the three most common cereal-food matrixes in starch digestion.