Characterisation of gluten-free pasta through conventional and innovative methods: Evaluation of the cooking behaviour

The rapid stiffening of a well-developed gluten network able to entrap swollen starch granules is a key factor for the high quality of durum wheat pasta during cooking. Good resistance and firmness, low stickiness and limited release of organic materials into the cooking water are quality traits of primary importance for traditional pasta. In gluten-free (GF) pasta, the formation of a scaffold of retrograded starch can be an alternative to gluten networking: it confers rigidity to the cooked product and reduces pasta stickiness and loss of soluble materials into the cooking water. In a previous paper, 14 commercial GF spaghetti samples were studied as uncooked products from a chemical, biochemical and physical point of view. The aim of this study was to determine the cooking behaviour of these samples. A durum wheat pasta was also included as reference. Suitable cooking conditions were adopted and different conventional and innovative evaluations (i.e. compression test, creep test) were performed as a function of cooking time. Different behaviours were evidenced, often related to the ultrastructural organization of the uncooked products. In particular, the creep test revealed to be very effective in discriminating among the properties of the different GF spaghetti.     

Characterisation of gluten-free pasta through conventional and innovative methods: Evaluation of the cooking behaviour

The rapid stiffening of a well-developed gluten network able to entrap swollen starch granules is a key factor for the high quality of durum wheat pasta during cooking. Good resistance and firmness, low stickiness and limited release of organic materials into the cooking water are quality traits of primary importance for traditional pasta. In gluten-free (GF) pasta, the formation of a scaffold of retrograded starch can be an alternative to gluten networking: it confers rigidity to the cooked product and reduces pasta stickiness and loss of soluble materials into the cooking water. In a previous paper, 14 commercial GF spaghetti samples were studied as uncooked products from a chemical, biochemical and physical point of view. The aim of this study was to determine the cooking behaviour of these samples. A durum wheat pasta was also included as reference. Suitable cooking conditions were adopted and different conventional and innovative evaluations (i.e. compression test, creep test) were performed as a function of cooking time. Different behaviours were evidenced, often related to the ultrastructural organization of the uncooked products. In particular, the creep test revealed to be very effective in discriminating among the properties of the different GF spaghetti.     

The Null-4A Allele at the Waxy Locus in Durum Wheat affects Pasta Cooking Quality

Granule-bound starch synthase, also known as the waxy protein catalyses the synthesis of amylose in wheat endosperm starch. In durum wheats, the genes encoding GBSS are present at the two Wx loci on chromosome 7A and 4A (a segment of 7B that has been translocated). Several null Wx-B1 (missing GBSS protein from chromosome 4A) durum lines were produced from crosses with null-4A bread wheats backcrossed to durum wheats. Semolina milled from 4 normal and 7 null-4A durum wheat lines grown over two seasons (1999 and 2000) in South Australia were analysed for amylose content, starch pasting properties as measured by the Rapid Viscoanalyzer (RVA), swelling power and starch damage, protein content and electrophoretic protein analysis. Spaghetti was prepared with a micro-scale extruder and the cooked pasta evaluated for cooking loss, firmness, stickiness and water absorption. The null-4A lines had significantly lower (ca. 5%) amylose content, higher starch peak viscosities and semolina swelling power. The pasta derived from the null-4A lines had lower cooking loss and in 1999 was more adhesive than the non-waxy lines. Cooking loss was correlated with amylose content, peak starch viscosity, swelling power of semolina and cooked pasta adhesiveness. Semolina swelling power was highly correlated with RVA peak viscosity. Waxy durum wheats appear to have an advantage over the normal types in terms of lower cooking loss, widely used as an indicator of pasta cooking quality.     

Influence of the addition of buckwheat flour and durum wheat bran on spaghetti quality

The quality of nine spaghetti typologies, produced by using wheat durum semolina as a base plus the addition of buckwheat and durum wheat bran, was investigated. The quality of the produced spaghetti was compared with that of spaghetti made only of durum semolina (CTRL). Tests were run on the samples to determine breakage susceptibility and colour of dry spaghetti, the cooking resistance, instrumental stickiness at optimal cooking time (OCT) and overcooking, the cooking loss and sensorial attributes at the optimal cooking time. Results suggest that the breakage susceptibility decreases with the addition of 15% and 20% bran, the spaghetti dry colour changes with the addition of buckwheat flour and bran compared to the spaghetti made only of durum semolina, while the cooking resistance, instrumental stickiness and the cooking loss, in general, were equal to that of the CTRL. However, the addition of buckwheat flour and bran affected the sensorial attributes differently.     

Effect of the grain protein content locus Gpc-B1 on bread and pasta quality

Grain protein concentration (GPC) affects wheat nutritional value and several critical parameters for bread and pasta quality. A gene designated Gpc-B1, which is not functional in common and durum wheat cultivars, was recently identified in Triticum turgidum ssp. dicoccoides. The functional allele of Gpc-B1 improves nitrogen remobilization from the straw increasing GPC, but also shortens the grain filling period resulting in reduced grain weight in some genetic backgrounds. We developed isogenic lines for the Gpc-B1 introgression in six hexaploid and two tetraploid wheat genotypes to evaluate its effects on bread-making and pasta quality. In common wheat, the functional Gpc-B1 introgression was associated with significantly higher GPC, water absorption, mixing time and loaf volume, whereas in durum wheat, the introgression resulted in significant increases in GPC, wet gluten, mixing time, and spaghetti firmness, as well as a decrease in cooking loss. On the negative side, the functional Gpc-B1 introgression was associated in some varieties with a significant reduction in grain weight, test weight, and flour yield and significant increases in ash concentration. Significant gene × environment and gene × genotype interactions for most traits stress the need for evaluating the effect of this introgression in particular genotypes and environments.     

Increasing atmospheric CO2 modifies durum wheat grain quality and pasta cooking quality

The present study focused on the quality traits of durum wheat grains (protein and content, gluten content, yellow pigment content), semolina (gluten index and yellow index) and pasta (firmness, yellow index, cooking time) obtained from 12 durum wheat genotypes grown under elevated atmospheric CO₂ concentration in an open field Free Air CO₂ Enrichment (FACE) experiment. The aims were to evaluate the impact of elevated CO₂ on durum wheat pasta making related traits as well as investigate genetic differences existing in a panel of old and modern cultivars. The protein content showed a not significant decrease (7%), the GC decreased significantly (13.3%), while the GI showed an increasing significant tendency (14%). The overall pasta quality (firmness and weight) worsened in ELE. Correlation between all traits and pasta firmness demonstrated that the decrease in pasta firmness under ELE was correlated with GPC and GC while it was not with the GI. All varieties, although to different extent, showed lower pasta firmness values compared to the ambient condition. Among the varieties tested, some were more sensitive than others to the increased atmospheric CO₂ concentration, a finding that can be exploited by breeding for designing novel genotypes with lower sensitivity to increased atmospheric CO₂.     

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.     

Effects of suni-bug (Eurygaster spp.) damage on semolina properties and spaghetti quality characteristics of durum wheats (Triticum durum L.)

Effects of suni-bug (Eurygaster spp.) damage on semolina properties and spaghetti quality characteristics of durum wheats (Triticum durum L.) were investigated. The semolinas obtained from sound (control), medium damage (around 20%) and high damage (around 40%) samples of five durum wheat cultivars (cvs. Diyarbakir, Firat, Ege, Svevo and Zenith) were processed into spaghetti. As the bug damage level increased, Glutograph stretch values of all cultivars decreased significantly probably due to deteriorative effects of bug damage on gluten quality. Glutograph relaxation values and gluten spread values of the damaged samples were considerably higher compared to those of sound samples in all cultivars, due to proteolytic degradation. The breaking force of the uncooked spaghetti samples decreased significantly with increasing bug damage level indicating that they were susceptible to breakage and not suitable for handling, packaging and shipment. Panel tests indicated significant deterioration in sensory properties (stickiness, firmness and bulkiness) generally at the medium damage level.     

Pastamaking and breadmaking quality of soft-textured durum wheat lines

The effects of grain texture on pastamaking and breadmaking quality were studied in three F₈ soft-textured durum wheat lines (SDLs) containing wild-type alleles Pina-D1a and Pinb-D1a as compared with their hard durum sister lines (HDLs). SDLs homozygous for a small 5DS segment, less than 14.4 cM in size, accumulated puroindolines A (Pin-A) and B (Pin-B) and showed SKCS values (19.9-23.6) significantly lower than those (72.6-76.8) of their hard-textured counterparts lacking Pin-A and Pin-B. In addition, SDLs exhibited approximately 24% higher flour extraction rates compared with HDLs. Reducing the kernel hardness decreased farinograph water absorption, dough tenacity (P) and, accordingly, alveograph P/L ratio, but increased farinograph stability, mixing tolerance and dough extensibility (L). Spaghetti cooking quality, as determined by the sensory judgment of firmness, stickiness and bulkiness, was unaffected by the kernel hardness, whereas the loaf volume exhibited a 10% increase associated with kernel softening. Flour and semolina, but not spaghetti, from SDLs showed a substantial reduction in yellowness (b^*) and brownness (100 − L^*) likely due to their finer particle size compared with HDLs. Alleles Pina-D1a and Pinb-D1a may offer new perspectives for breeding dual purpose (pasta and bread) durum wheat varieties.     

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.     

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.     

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.     

Kernel vitreousness and protein content: Relationship,interaction and synergistic effects on durum wheat quality

Four sets of durum samples were used in this study to further understand the interrelationships among hard vitreous kernels (HVK), protein content, and pigment concentration, with a focus on the interaction and synergistic effects of protein content and vitreousness on durum quality. HVK level increases with higher protein content in the range of 9.5–12.5%, but this relationship is less evident in durum samples with high protein content (12.5–14.5%). Both protein content and kernel vitreousness can significantly affect durum milling quality. White starchy kernels (WSK) in low protein durum have a very detrimental impact on milling and pasta processing quality, but high protein content can mitigate the adverse impact of WSK on durum quality. Although protein content plays a dominant role, higher HVK might contribute positively to pasta firmness. There was no significant difference in yellow pigment content between HVK and WSK. However, pigment loss from semolina to dough was higher for WSK than HVK. Despite the difference in protein content, HVK and WSK have little difference in gluten strength. The monomeric protein was preferentially accumulated in HVK. The glutenin proteins of HVK and WSK were similar in the ratios of 1Bx/1By and HMW/LMW-GS.     

In vitro starch digestibility,degree of gelatinization and functional properties of twin screw prepared cereal-legume pasta

The investigation explores the possibility of utilizing legume flour (pigeon pea:10–30%) and brown rice flour (35–45%) for production of pasta using twin screw extruder. RSM was used to analyse the effect of feed moisture (28–36%), barrel temperature (70–110 °C) and legume:brown rice ratio on quality responses (in vitro starch and protein digestibility, degree of starch gelatinization, cooking quality, pasting properties, color and textural properties) of pasta. Extrusion processing significantly enhanced in vitro starch and protein digestibility of prepared pasta. The in vitro starch and protein digestibility of pasta ranged between 15.00 and 26.77 g/100 g and 50.34–84.82 g/100 g respectively. Addition of brown rice flour and pigeon pea flour exhibited dominating positive effect on cooking quality of the pasta. Degree of gelatinization of prepared pasta was found in range of 52.13–90.10 per cent. Color characteristics viz. luminosity, redness and yellowness of pasta enhanced with feed moisture. Pasting properties revealed lower peak and final viscosity at higher processing conditions. Firmness of cooked pasta elevated with an increase in the barrel temperature. Acceptability score of health based pasta on the basis of sensory attributes was 8 as inferred from 9 point hedonic scale.     

Metabolic profiling and analysis of volatile composition of durum wheat semolina and pasta

Although pasta is generally not considered for its aromatic properties, some evidence proves that cereal flours release volatile compounds and they might have an effect on the aroma of the transformed products. This work reports on the characterization of the volatile components of semolina and pasta obtained from four durum wheat cultivars (Triticum durum Desf., cvs. PR22D89, Creso, Cappelli, Trinakria). Semolina samples were characterized through polar metabolite profiling and fatty acid analysis to identify potential precursors of the volatile components. The results show significant differences among the samples tested with cv. Trinakria characterized by the highest content of sugars and fatty acids. Volatile composition was investigated both in semolina and in cooked pasta using headspace solid-phase micro-extraction (HS-SPME) and identified by GC–MS. Thirty-five volatile compounds including aldehydes, ketones, alcohols, terpenes, esters, hydrocarbons and a furan were identified. Significant differences were observed between semolina and pasta samples in terms of composition and amount of the volatile compounds. During cooking an increase in aldehyde content, the appearance of ketones and a decrease in alcohol content were observed. Correlations between metabolites and volatiles demonstrate that the flavour of cooked pasta may differ significantly depending on the durum wheat cultivar employed.     

Quality Characteristics of Durum Wheat Lines Deriving High Protein From aTriticum dicoccoides(6b) Substitution

One of the objectives in the Canadian durum wheat (Triticum turgidumL.) breeding programs has been the selection of lines having higher protein content. The Langdon-dicoccoides(Triticum dicoccoides6B) substitution, a source of high protein, has been introgressed into two high yielding, but lower protein Canadian lines of durum wheat. The resulting lines with protein content similar to registered cultivars were evaluated for protein quality. The introgression had no detrimental effects upon pasta cooking quality, and thus the dicoccoides 6B chromosome substitution will be a valuable route to increasing protein level for the durum wheat breeding program.     

Vitreosity,its stability and relationship to protein content in durum wheat

High quality requirements are set on durum wheat (Triticum durum) from semolina mills and pasta producers. For the production of semolina and pasta with good cooking quality, high grain protein content and vitreosity is required. The dependency of vitreosity on protein content as well as its stability under the influence of humidity was not well investigated up to now. We (1) compared two methods to determine vitreosity, (2) investigated the relationship between vitreosity and protein content, (3) developed a method to analyze vitreosity under humidity, and (4) examined the relationship between protein content and agronomical as well as quality traits in durum wheat. The results showed that the formation of vitreous kernels greatly depends on the protein content. To evaluate the stability of vitreosity under the influence of humidity a new method was elaborated and employed to assess the durum germplasm under study. This revealed that vitreosity of a durum wheat variety depends on the potential to form vitreous kernels but also to maintain this vitreosity under the influence of humidity. Our results further show that protein content is a central trait in durum wheat that strongly influences important traits like grain yield, vitreosity, and b-value.     

Contributions of individual and combined Glu-B1x and Glu-B1y high-molecular-weight glutenin subunits to semolina functionality and pasta quality

Durum wheat is an important food crop used primarily for pasta production. High-molecular-weight glutenin subunits (HMW-GS) encoded by the closely linked genes Glu-B1x and Glu-B1y are known for their combined effects on pasta quality, but their individual contributions and interactions remain poorly understood. In this study, we show that individual loss-of-function mutants of Glu-B1x (ΔBx6) and Glu-B1y (ΔBy8) were associated with significant reductions in gluten strength compared to the wildtype, with stronger effects in the ΔBxy double mutant. Reductions in gluten strength were reflected in reduced mixograph and alveograph parameters, gluten index, faster extrusion flow rates and increased cooking loss. Interestingly, the Glu-B1x mutation was also associated with significant increases in grain and semolina protein content, increased pasta firmness, reduced starch viscosity and increased amylose in ΔBx6 and ΔBxy. In general, the ΔBx6 mutation had stronger effects than the ΔBy8 mutation, and significant interactions between the two genes were frequent. In addition to the basic knowledge gained on the individual effects of the Bx6 and By8 subunits and their interactions, the genetic stocks developed in this study provide useful tools to study the effects of natural or synthetic HMW-GS on pasta quality parameters in a background lacking endogenous HMW-GS.     

Comparison of Various Processes for Making Maize Pasta

Maize pasta was produced using various heat treatment such as drum-drying, extrusion-cooking, pasting and steaming. Cooking quality of pasta products were compared and discussed on the basis of starch physico-chemical properties. The best products were obtained by using drum-drying or pasting, whereas the worst product was obtained using extrusion-cooked maize starch. This was interpreted in terms of starchy component degradation and amylose retrogradation ability. The treatment of fresh pasta at high temperature (95°C) with high relative humidity (95%) improved pasta quality: after 1 h under these conditions, cooking losses were decreased by 9%. Addition of monoglycerides also significantly improved pasta cooking quality by making complexes with amylose during pasta cooking. In contrast, cold storage promoted amylopectin retrogradation and scarcely improved maize pasta quality.     

Influence of hydrothermal treatment on rheological and cooking characteristics of fresh egg pasta

The effect of D.I.C. processing conditions on rheological and cooking properties of commercial fresh egg pasta was studied. The mechanical properties of pasta before and after cooking were evaluated by empirical test and characterised by maximal apparent force (F_max) and apparent relaxation coefficient (ARC). Structural (apparent density) and cooking quality were evaluated by determining mass ratio (W/Wo), optimal cooking time (OCT), swelling index (SI), solid, soluble and total cooking losses (TCL) and compared to untreated pasta. The hydrothermal treatment caused a reduction in firmness and relaxation capacity of treated pasta. The increase of processing conditions induced a decrease of F_max and the processing time has an influence when it is associated to the low pressures. The values of ARC vary from 51% (untreated pasta) to 37% (D.I.C. treated pasta). The increase of processing time from 30 to 60 s does not seem to have a significant influence on ARC. The apparent density of treated pasta is a function of processing pressure and time but it is always lower than untreated pasta density. Treated pasta had a higher quality score based on water sorption and SI and matter losses (TCL values and solid and soluble losses) as compared to untreated pasta.