Quality of Fiber‐Enriched Spaghetti Containing Microbial Transglutaminase

The effects of transglutaminase (TG) on the properties of semolina dough and pasta cooking properties in durum‐only and fiber‐enriched pasta were investigated. TG was blended at levels 0, 0.05, 0.1, 0.25, 0.5, and 1% of semolina weight with semolina and semolina‐pollard (60% w/w) and semolina‐guar gum (15%) mixtures. The addition of TG increased dough maximal resistance, making the dough inextensible at >1%. Optimum effects on dough strength were obtained at 0.5% TG; this dough gave the firmest and least sticky pasta. A more extensive and thicker protein matrix was observed in the TG pasta by confocal scanning laser microscopy, indicating more cross‐links were formed, a finding supported by measuring percentage of unextracted polymeric protein. TG was unable to overcome the negative effect of 60% pollard on cooking loss or 15% guar gum on stickiness. Gluten was generally more effective than TG in restoring the properties of pastas with added fiber.     

Spelt (Triticum spelta L.) Pasta Quality: Combined Effect of Flour Properties and Drying Conditions

Three spelt genotypes (Rouquin, Redoute, and HGQ Rouquin= Rouquin improved for gluten quality), each characterized by either high or low protein content, were processed to manufacture spaghetti, which was dried at both low (60°C) and high temperature (90°C) to assess the effects of flour properties and drying conditions on spelt pasta quality. Protein content in the spelt flour was considered low at ≈11.4% db and high at ≈13.5% db. Gluten properties, assessed by SDS sedimentation and gluten index values and by alveograph and farinograph parameters varied widely, ranging from poor for Redoute to very good for HGQ Rouquin. Pasta quality was assessed by determining color (L*, a*, and b* values), furosine, and cooking quality (stickiness, bulkiness, firmness, and total organic matter [TOM]). Furosine and color (a* and b* values) were significantly influenced by the intensity of the drying process. TOM and organoleptic judgement (OJ) showed that spelt pastas dried at low temperature, independent of their protein levels, were very poor (TOM ≥ 2.7 g/100 g of dry pasta, OJ ≤ 40), except for HGQ Rouquin which was characterized by good gluten strength. On the other hand, the cooking quality of spelt pastas dried at high temperature showed good values (TOM ≤ 1.8 g/100 g of dry pasta, OJ ≥ 53). The combination of high protein content (≥13.5% db) and high‐temperature drying resulted in the production of satisfactory cooking quality pastas from spelt wheats (TOM ≤ 1.2 g/100 g of dry pasta, OJ ≥ 67).     

Small‐Scale Reconstitution of Durum Semolina Components

Pasta prepared by extrusion from 25 g of semolina has been compared with that made from a standard laboratory extruder and found to have similar quality. Durum semolina was fractionated into its starch, gluten, water soluble, and residue fractions. The freeze‐dried components were reconstituted and the properties of the reconstituted semolina (ReSem) have been measured. Examination using a 2 g‐mixograph and micro‐extension tester has shown that ReSem behaves similarly to the original semolina. ReSem and semolina were made into pasta using a small‐scale pasta extruder and were of comparable cooking quality. The fractionation and reconstitution of durum semolina on this scale is a useful technique to evaluate the contribution of semolina components to pasta quality.     

Effect of Hydrocolloids on Water Absorption of Wheat Flour and Farinograph and Textural Characteristics of Dough

The effect of hydrocolloids addition (0, 25, or 1.5 g/100 g of flour) on water absorption of flour and their influence on dough rheology were analyzed. The influence of guar gum (GG), xanthan gum (XG), high‐methoxyl pectin (P), locust bean gum (LBG), and a 1:1 mixture of locust bean gum and xanthan gum (LBG+XG) on water absorption was tested by different techniques including farinograph water absorption, water imbibing capacity, SDS sedimentation test, and sucrose solvent retention capacity. The rheological behavior was analyzed through the farinograph parameters and texture profile analysis (TPA). Principal component analysis (PCA) was applied to evaluate the behavior of the different mixtures. Absorption values obtained by different methods were increased by XG and LBG+XG addition, particularly at the highest levels (1–1.5%). Flour‐P mixtures showed the lowest absorption. GG‐added mixtures led to the more stable doughs and P to the less stable ones. Addition of NaCl increased stability in all cases. According to TPA, softer and less cohesive doughs than control were obtained when hydrocolloids were added, both in conditions of water availability and water restriction (except for XG and GG at the highest levels). However, when enough water was added, more variation in textural attributes among doughs could be observed by PCA. No remarkable differences compared with the control were observed in the gluten network, as evaluated by scanning electron microscopy. Hydrocolloid incorporation led to rheological changes in dough; the trend and degree of this effect was affected by the amount of water added and the structure and concentration of the hydrocolloid.     

Influence of Gluten Proteins and Drying Temperature on the Cooking Quality of Durum Wheat Pasta

It is well known that gluten plays a major role in determining cooking quality in durum wheat pasta. This work is an attempt to systematically elucidate the role of gluten quantity and nature in determining cooking quality as a function of the drying cycle used in the manufacturing process. Gluten and starch were fractionated from two durum wheat cultivars possessing good and poor gluten quality. Either of them were then added back to the original base semolina to alter its protein content and to produce two semolina series with identical protein contents. Semolinas were processed into pasta and dried following three drying programs (low, medium, and high temperature). Cooking quality was determined with sensorial, chemical, and instrumental methods. The results indicate that optimum cooking time is governed by gluten quality. The positive effect on cooking quality of increasing gluten contents and of the application of HT drying is evident in weak gluten samples, but it is not significant in the strong gluten samples.     

Textural Comparisons of Gluten‐Free and Wheat‐Based Doughs,Batters, and Breads

Studies were conducted with two newly developed gluten‐free bread recipes. One was based on corn starch (relative amount 54), brown rice (25), soya (12.5), and buckwheat flour (8.5), while the other contained brown rice flour (50), skim milk powder (37.5), whole egg (30), potato (25), and corn starch (12.5), and soya flour (12.5). The hydrocolloids used were xanthan gum (1.25) and xanthan (0.9) plus konjac gum (1.5), respectively. Wheat bread and gluten‐free bread made from commercial flour mix were included for comparison. Baking tests showed that wheat and the bread made from the commercial flour mix yielded significantly higher loaf volumes (P < 0.01). All the gluten‐free breads were brittle after two days of storage, detectable by the occurrence of fracture, and the decrease in springiness (P < 0.01), cohesiveness (P < 0.01), and resilience (P < 0.01) derived from texture profile analysis. However, these changes were generally less pronounced for the dairy‐based gluten‐free bread, indicating a better keeping quality. Confocal laser‐scanning microscopy showed that the dairy‐based gluten‐free bread crumb contained network‐like structures resembling the gluten network in wheat bread crumb. It was concluded that the formation of a continuous protein phase is critical for an improved keeping quality of gluten‐free bread.     

Characterization of Durum Wheat Semolina by Means of a Rapid Shear‐Based Method

A rapid shear‐based test (the GlutoPeak test, recently proposed by Brabender) was used to investigate gluten aggregation properties of durum wheat semolina and to relate them to pasta cooking behavior. Thirty semolina samples were characterized by means of the conventional approaches used for pasta‐quality prediction (protein content, gluten index, and alveographic indices). All samples were also analyzed by the GlutoPeak test, obtaining three parameters: maximum peak torque, maximum peak time, and area under the peak. The GlutoPeak indices were significantly correlated with protein content, gluten index, and W alveographic parameter. The cooking quality of pasta obtained from the 30 semolina samples was evaluated by sensory analysis in terms of stickiness, bulkiness, firmness, and overall quality. The GlutoPeak indices were significantly correlated with the sensorial parameters. In comparison with the alveographic test, which is presently the most used rheological approach for semolina characterization, GlutoPeak analysis presents some advantages represented by a smaller amount of sample (9 g), a shorter time (less than 5 min), and the possibility that untrained analysts can carry it out. In addition, following testing with larger sample numbers, the GlutoPeak test has the potential to be used instead of the gluten index as a rapid and reliable approach for medium‐quality semolina characterization.     

Protein-enriched spaghetti fortified with corn gluten meal

Spaghetti was prepared by replacing either 5 or 10% semolina or farina with corn gluten meal, a high-protein fraction from the wet milling of corn, to increase the protein content of pasta. Spaghetti fortified with corn gluten meal had a similar cooked weight and cooking loss but was less firm compared with the control. The overall flavor quality score of the spaghetti decreased with the increasing additions of either water-washed, water/ethanol-washed or regular corn gluten meal because of the higher intensity of the fermented flavor. Spaghetti with acceptable quality can be prepared with 5% water/ethanol-washed corn gluten meal, thereby improving its nutritional value while providing an additional market for corn gluten meal.     

A New Method to Study Simple Shear Processing of Wheat Gluten‐Starch Mixtures

This article introduces a new method that uses a shearing device to study the effect of simple shear on the overall properties of pasta‐like products made from commercial wheat gluten‐starch (GS) blends. The shear‐processed GS samples had a lower cooking loss (CL) and a higher swelling index (SI) than unprocessed materials, suggesting the presence of a gluten phase surrounding starch granules. Pictures of dough micro‐structure by confocal scanning laser microscopy (CSLM) showed the distribution of proteins in the shear‐processed samples. This study revealed that simple shear processing could result in a product with relevant cooking properties as compared with those of commercial pasta. Increasing gluten content in GS mixtures led to a decrease in CL and an increase in maximum cutting stress of processed samples, whereas no clear correlation was found for SI values of sheared products. It was concluded that the new shearing device is unique in its capability to study the effect of pure shear deformation on dough development and properties at mechanical energy and shear stress levels relevant to industrial processing techniques like pasta extrusion.     

In Vitro Starch Digestibility of Gluten‐Free Spaghetti Based on Maize,Chickpea, and Unripe Plantain Flours

Gluten‐free and high indigestible carbohydrate food development is a topic that deserves investigation because of an increased focus on gluten intolerance and celiac disease and on metabolic disorders caused by overweight and obesity. Here, chickpea and maize flours were used as sources of protein and carbohydrate (because of the level used in the mixture) and unripe plantain as an indigestible carbohydrate source in composite gluten‐free spaghetti elaboration. The mixture of unripe plantain, chickpea, and maize was used at different levels to prepare spaghetti (samples S15Pla and S25Pla); control pasta was made of 100% semolina (S100Sem), and a 100% unripe plantain flour (S100Pla) pasta was also evaluated. In vitro amylolysis rate of fresh and stored (three and five days) spaghetti was assessed. The spaghetti with 100% unripe plantain (S100Pla) had higher resistant starch (RS) content than the control sample and the two cooked composite gluten‐free spaghettis (S15Pla, S25Pla), and RS further increased with the storage time. The plantain spaghetti (S100Pla) also had the highest rapidly digestible starch and the lowest slowly digestible starch contents; this pattern agrees with the hydrolysis rate, especially after cold storage. The stored S25Pla spaghetti showed the lowest hydrolysis rate and predicted glycemic index. Blending chickpea, maize, and unripe plantain flours represents a way to obtain gluten‐free spaghetti with high nondigestible carbohydrate content and slow digestion properties.     

Effects of Drying Processing Conditions on the Quality of Uncooked and Cooked Pasta Made Up of Nonconventional Raw Material

Drying process plays a fundamental role in pasta making. The greatest number of studies have been focused on the optimization of drying conditions for semolina pasta, and the obtained results have been applied in a similar way on pasta made up of nonconventional raw materials without considering a processing optimization. The aim of this research was to evaluate the influence of different drying treatments (low, medium, and high temperature) on the quality of uncooked and cooked soft wheat pasta enriched with oat flour. Results of total organic matter and dried residue showed no significant difference between samples dried by medium and high temperature treatments. Moreover, these last samples showed a slight improvement in cooking quality over samples dried at low temperature (total organic matter results were 1.31 versus 1.66 g/100 g of dried pasta). This study revealed that the improvement of cooking quality of pasta enriched with oat flour did not require the application of high drying temperature (>80°C) that involves a considerable consumption of energy and could favor the development of a Maillard reaction, decreasing quality characteristics of this kind of product.     

Effect of Source and Proportion of Waxy Starches on Pasta Cooking Quality

Starches from the endosperm of three types of total‐waxy cereals (bread wheat, maize, and barley) were used in reconstitution studies of durum wheat semolinas to investigate the effect of waxy starch on pasta cooking quality. The chemical composition and the pasting and gelatinization properties of the starches used in this study were evaluated to define the functional properties of each waxy starch. The rheological properties of dough semolinas were evaluated by small‐scale mixograph. Spaghetti was prepared using a small‐scale pasta extruder and its cooking quality was assessed using a texture analyzer. Cooked pasta firmness, resilience, and stickiness were measured. The substitution of semolina starch with waxy starches from different sources changed the functional properties of dough and their pasta quality. A decrease in firmness was detected in all the semolinas reconstituted with waxy starches. An increase in stickiness was found when semolinas with waxy starch from wheat were evaluated. No improvement in pasta quality should be expected if the waxy character is introduced in durum wheat.     

Water-extractable and water-unextractable arabinoxylans affect gluten agglomeration behavior during wheat flour gluten-starch separation

Water-extractable arabinoxylan (WE-AX) of variable molecular weight (MW) and water-unextractable arabinoxylan (WU-AX) were added to wheat flour to study their effect on gluten agglomeration in a dough and batter gluten-starch separation process with recovery of gluten from the batter with a set of vibrating sieves (400, 250, and 125 microm). Low MW WE-AX had almost no impact on the distribution of the gluten on the different sieves. High MW WE-AX decreased yields of the largest (400 microm sieve) gluten aggregates, more than their medium MW counterparts, indicating the importance of AX MW for their effect on gluten interactions. Correlations between the total level of gluten protein recovered on the three sieves and the batter extract viscosity as well as between the proportion of gluten protein recovered on the 400 microm sieve to that on the three sieves and the batter extract viscosity pointed to the importance of viscosity as an indicator for gluten agglomeration, as did the fact that another viscosity increasing plant polysaccharide (guar gum) also negatively influenced gluten agglomeration. However, the obtained data cannot rule out that AX and guar gum also exert steric effects on gluten agglomeration. WU-AX, present as discrete cell wall fragments, had a negative impact on the level of large gluten aggregates. Taken together, the results show that both native WE-AX and WU-AX detrimentally impact gluten agglomeration.     

Gluten Structural Evolution During Pasta Processing of Refined and Whole Wheat Pasta from Hard White Winter Wheat: The Influence of Mixing,Drying, and Cooking

An attempt was made to evaluate gluten structural changes in refined and whole wheat pasta from hard white winter wheat to elucidate the impact of whole wheat components on the formation and structure of the gluten network in pasta. Attenuated total reflectance–FTIR spectroscopy was used to track gluten secondary structure through most of the major steps in pasta processing: raw material, mixing, drying, and cooking. Protein solubility, accessible thiols, and SDS‐PAGE data were also collected to provide additional information on the nature of protein interactions and network composition. Few secondary structural differences were observed between refined and whole wheat flours from hard white wheat. However, mixing induced a significant shift to β‐sheet structures in refined dough that was not equally matched by whole wheat dough. Drying under both high temperature, short time (HT) and low temperature, long time (LT) conditions resulted in a reversion to structural distributions similar to those for flour in both pastas. However, greater protein denaturation in HT samples was indicated by lower protein solubility also in the presence of denaturants and disulfide reducing agents. Cooking generated a substantial increase in β‐sheet structures for both pasta systems. This structure was greatest in refined and LT samples. Thiol accessibility data indicate the presence of a highly aggregated, compact gluten network in refined pasta, mostly driven by hydrophobic association. Conversely, the network in whole wheat pasta was more loosely associated and dependent on disulfide bonding, both of which fit well with the secondary structural data.     

Fractionation and reconstitution experiments provide insight into the role of starch gelatinization and pasting properties in pasta quality

Commercial durum wheat semolina was fractionated into protein, starch, water-extractable, and sludge fractions. The starch fraction was hydroxypropylated, annealed, or cross-linked to change its gelatinization and pasting properties. Spaghettis were made by reconstitution of the fractions, and their quality was assessed. Hydroxypropylated starches were detrimental for cooked pasta quality. Cross-linked starches made the reconstituted pasta firmer and even brittle when the degree of cross-linking was too high. These results indicate that starch properties play a role in pasta quality, although the gluten remains very important as an ultrastructure agent. It was concluded that, given a certain gluten ultrastructure, starch water uptake and gel properties and/or its interference with or breakdown of the continuous gluten network during cooking determine pasta quality.     

Fractionation and reconstitution experiments provide insight into the role of gluten and starch interactions in pasta quality

Commercial durum wheat (Triticum durum desf.) semolina was fractionated into starch, gluten, and water extractables. Starch surface proteins and surface lipids were removed, and two starches with manipulated granule size distributions were produced to influence starch properties, affecting its interaction with other semolina components. Reconstituted spaghetti was made with untreated (control) or treated starches. The pasta made from the starting semolina material had lower cooking time and was of lower quality than the samples made from reconstituted material. This was not due to changes in gluten properties as a result of the first step of the fractionation process. For the reconstituted samples, starch interaction behavior was not changed after surface protein or surface lipid removal. Starch surface properties thus do not influence the starch interaction behavior, indicating that starch-gluten interaction in raw (uncooked) pasta is mainly due to physical inclusion. All reconstituted pasta samples also had generally the same cooking quality. It was concluded that the small changes in starch gelatinization behavior, caused by the above-mentioned starch modifications, are of little importance for pasta quality.     

Fermented pigeon pea (Cajanus cajan) ingredients in pasta products

Pigeon pea (Cajanus cajan var. aroíto) seeds were fermented in order to remove antinutritional factors and to obtain functional legume flour to be used as pasta ingredients. Fermentation brought about a drastic reduction of alpha-galactosides (82%), phytic acid (48%), and trypsin inhibitor activity (39%). Fermented legume flours presented a notable increase of fat and total soluble available carbohydrates, a slight decrease of protein, dietary fiber, calcium, vitamin B2, vitamin E, and total antioxidant capacity, and a decrease of soluble dietary fiber, Na, K, Mg, and Zn contents. No changes were observed in the level of starch and tannins as a consequence of fermentation. The fermented flour was used as an ingredient to make pasta products in a proportion of 5, 10, and 12%. The supplemented pasta products obtained had longer cooking times, higher cooking water absorptions, higher cooking loss, and higher protein loss in water than control pasta (100% semolina). From sensory evaluations, fortified pasta with 5 and 10% fermented pigeon pea flour had an acceptability score similar to control pasta. Pasta supplemented with 10% fermented pigeon pea flour presented higher levels of protein, fat, dietary fiber, mineral, vitamin E, and Trolox equivalent antioxidant capacity than 100% semolina pasta and similar vitamins B1 and B2 contents. Protein efficiency ratios and true protein digestibility improved (73 and 6%, respectively) after supplementation with 10% fermented pigeon pea flour; therefore, the nutritional value was enhanced.     

Qualitative Effect of Added Gluten on Dough Properties and Quality of Chinese Steamed Bread

Glutens isolated from 15 soft red winter (SRW) wheat flours were added into a SRW wheat flour to obtain protein levels of 9.6 and 11.3% for determination of the qualitative effect of added gluten on the dough properties and quality of northern‐style Chinese steamed bread (CSB). Sodium dodecyl sulfate sedimentation (SDSS) volume of the gluten source flour exhibited positive relationships with mixograph absorption, midline peak time (MPT), and midline peak value (MPV) of the gluten‐added flours and with surface smoothness, crumb structure, and total score of CSB prepared from the gluten‐added flours regardless of protein content. Positive correlations were also observed between SDSS volume of the gluten source flour and specific volume and stress relaxation score of CSB prepared from the gluten‐added flours of 11.3% protein. The increase in protein content from 9.6 to 11.3% by gluten addition raised mixograph absorption, MPT, and MPV but had no apparent effect on resistance breakdown, dough maximum force for extension, and extensibility, and it increased CSB specific volume and crumb structure score without affecting surface smoothness, stress relaxation, and total score. Mixograph parameters exhibited significant relationships with CSB total score, indicating that they could be effective predictors of the CSB‐making quality of flours.     

Rheological and Pasting Properties of Buckwheat (Fagopyrum esculentum Möench) Flours With and Without Jet‐Cooking

Pasting, rheological, and water‐holding properties of buckwheat (Fagopyrum esculentum) flour obtained from whole achenes separated into three particle sizes, and three commercial flours (Fancy, Supreme, and Farinetta) were measured with or without jet‐cooking. Fancy had instantaneous paste viscosity (measured using RVA) after jet‐cooking that was not observed for Supreme or Farinetta, and paste viscosity was lower for the latter two flours. Supreme jet‐cooked flour exhibited higher peak viscosity than flour without jet‐cooking, and paste exhibited high shear‐thinning. Fancy exhibited strongest viscoelastic properties (measured using a rheometer). Jet‐cooking damaged buckwheat flour structure, thereby reducing viscoelasticity. Buckwheat flour pastes experienced shear‐thinning over a wide range of shear rates. Jet‐cooking greatly enhanced water‐holding capacity. Buckwheat flour particle size did not greatly influence paste viscosity. Study showed buckwheat flours have unique pasting and rheological characteristics that have different food applications, which could especially be useful for people with celiac disease as buckwheat is gluten‐free.     

Effect of β‐Glucan on Technological,Sensory, and Structural Properties of Durum Wheat Pasta

β‐Glucan is known to have valuable properties for preventative health and is finding widespread use in foods. This study investigated the benefit of adding a commercial source of β‐glucan, Barley Balance (BB) flour, as a functional ingredient in spaghetti. Durum wheat semolina was substituted with BB at levels of 7.5, 15, and 20%, from which spaghetti was prepared on a laboratory scale. The substitution of BB increased the β‐glucan content of semolina from 0.3 to 6% in uncooked and 8% in cooked pasta. Antioxidant activity (measured by 2,2‐diphenyl‐1‐picrylhydrazyl) increased with BB and did not decline significantly on processing and cooking. Compared with the control, 7.5% BB had no or minimal effect on pasta cooking loss, stickiness, water absorption, aroma, and sensory texture. However, at higher doses, pasta became less yellow and more brown, firmer, of inferior aroma, more rubbery, and chewy, but less floury to the mouth. The extent of starch digestion decreased with increasing quantities of BB, suggesting that BB may lower glycemic index, with microscopy data suggesting that this decrease was mediated through the development of a more intensive fiber or fiber/protein matrix retarding enzymatic access to starch granules.