784 research outputs found
Pasta: quality testing methods
No full textThe various aspects concerning pasta quality along the value chain will be presented, focusing on dry pasta. The measurement of pasta quality starts before cooking: color, surface properties, elasticity, and resistance to breakage are the main parameters evaluated on dried state. The evaluation of cooking performances is more complicated due to several modes of cooking and diverse eating habits around the world. Chemical, instrumental, and sensory tests currently used for evaluating pasta quality will be presented, highlighting their strengths and weaknesses
Effect of iodine in semolina matrices
Get PDFThe effect of starch-protein interactions on the ability of linear starch chains to bind iodine was investigated in 4 types of semolina. Based on K/S (absorption/scattering coefficient) spectra, obtained after equilibration above K 2SO 4 and exposure to iodine vapor, and X-ray diffraction, semolina samples showed differences in chain mobility, iodine-binding capacity and crystalline order. After removing protein from the samples, starch exhibited a higher iodine-binding capacity, suggesting greater starch chain mobility, and low crystalline order. The results suggest that protein and/or starch-protein affect the packing arrangement of starch polymers within the granule
Understanding starch organisation in gluten-free pasta from rice flour
Get PDFStarches extracted from parboiled rice flour and pasta samples produced by two extrusion processes - a conventional method carried out at 50 °C and an extrusion-cooking process at 115 °C - were evaluated by differential scanning calorimetry (DSC) and size exclusion chromatography (SEC) analysis. Molecular changes induced by both pasta-making process and following cooking in boiling water were also investigated using iodine absorption properties of samples expressed as the ratio of absorption to scattering spectra (K/S) and X-ray diffraction. A decrease in polymer chain mobility and iodine binding capacity were observed after pasta-making process. While the characteristic A-type crystalline pattern remained, the exposure to iodine vapor changed the peak intensity of starch samples, especially at 0.97 aw. The higher melting temperature of pasta samples in comparison with parboiled rice flour reflected the decrease in mobility of the amorphous regions detected by K/S spectral analysis. The pasta making-process also affected the molecular size distribution of starch samples. In particular, the elution peak shifted toward lower fraction numbers with increasing extrusion temperature, showing a higher molecular size for starch after the extrusion-cooking. All the differences detected between starch samples according to extrusion conditions were deleted during cooking. Compared to the uncooked samples, starch from cooked pasta showed higher K/S value at all wavelengths, highlighting the increase in mobility of the amorphous region. Moreover, beside the increase in melting temperature, a decrease in endothermic enthalpy was detected, confirming the loss of order observed by X-ray diffraction
Characterizing starch structure in a gluten-free pasta by using iodine vapor as a tool
Get PDFThe suitability of starch-iodine complex to highlight differences in chain mobility and crystallinity of starch in rice pasta was investigated. Two pasta samples were produced starting from the same rice flour (RF) and using a conventional extrusion process without (Process A) and with (Process B) a preliminary extrusion-cooking step. Based on the absorption/scattering coefficient (K/S) spectra (obtained after equilibration above K2SO4 and exposure to iodine vapor), Pasta A showed a behavior similar to RF. Process B exhibited a greater iodine binding capacity suggesting greater starch chain mobility. Moreover, the extrusion-cooking conditions seem to favor the loss of starch crystallinity and the formation of larger amorphous regions. The organization of starch polymers observed in Pasta B could account for its higher capacity to water absorption during cooking
Rheological properties of perennial wheatgrass (Thinopyrum intermedium) and its blends with wheat flour
No full textIntermediate wheatgrass (IWG) (Thinopyrum intermedium) is a perennial grass with desirable agronomic traits and positive effects on the environment. Its high fiber and protein contents have increased the interest in IWG for human consumption. As for improvement of IWG potential for food production, efforts are tied to understanding the functional properties of IWG. The aim of this study was to investigate starch physical properties and protein aggregation in IWG-only and IWG/hard wheat (HWF) systems. IWG-based doughs were prepared at 50%, 75% and 100% IWG levels in order to produce systems with total fiber content higher than 10%. The pasting properties of samples were evaluated using Micro Visco-Amylograph. Proteins in the various blends were characterized in terms of extractability, readily and SDS-accessible thiols. Gluten aggregation properties (using GlutoPeak) and mixing profile (using Farinograph) were also considered. IWG-enrichment increased the pasting temperature and decreased peak viscosity of blended flours. The former is related to the predominant presence of starch granules in IWG assembled together, whereas the latter to fiber content. IWG proteins were able to aggregate and form a gluten-like network that was less strong than HWF (GlutoPeak test). IWG-enrichment resulted in faster gluten aggregation and lower peak torque compared to HWF, suggesting a weakening of the gluten network. This is related to the high protein solubility of IWG. Moreover, despite the high level of thiol groups, these seem not to be as available for aggregating as in HWF. During mixing, IWG-enrichment resulted in an increase in consistency and a decrease in development time and dough stability, likely due to the higher levels of fiber and to differences in protein profile. The overall results suggest that 50% IWG-enrichment represents a good compromise between nutritional improvement and maintenance of the pasting properties, protein characteristics and gluten aggregation kinetics
Molecular features of wheat doughs enriched with perennial wheatgrass (Thinopyrum intermedium) flour
No full textThinopyrum intermedium – commonly known as intermediate wheatgrass (IWG) – is a perennial crop characterized by many desirable agronomic traits, such as high biomass yield, and drought and frost resistance. Moreover, the high fiber and protein contents increases the interest in using IWG for human consumption. The aim of this study was to investigate the protein structural features in IWGonly and IWG/wheat systems. IWG based doughs were prepared at ≥50% IWG enrichment in order to produce systems with a total fiber content higher than 10%. IWG-enrichment resulted in faster
gluten aggregation and lower peak torque compared to hard wheat flour (as measured by Glutopeak test), suggesting a weakening of the gluten network. Proteins in IWG-doughs had higher solubility
and thiol content - as function of IWG content - suggesting that protein network was mostly based on non-covalent interactions. Finally, IWG-enrichment enhanced the non-sheet/sheet ratio, by
increasing the unordered structures at the expenses of β-sheet structures but without affecting β-turn structures. The overall results suggest that a 50% IWG-enrichment represents a good
compromise between nutritional improvement and maintenance of the protein structural characteristics in dough
Structural characterization of proteins in wheat doughs enriched with perennial wheatgrass (Thinopyrum intermedium)
No full textIntermediate wheatgrass (IWG) (Thinopyrum intermedium) is a perennial crop whose development as an environmentally sound alternative crop for marginal lands has received recent attention among agronomists, plant breeders and environmentalists. The compositional attributes of IWG - high protein and fiber content - make this crop nutritionally attractive as well. However, characterization of the crop is necessary in view of the development of IWG-based products. The aim of this study was to investigate protein functionality in IWG and IWG/wheat dough. IWG-enriched doughs were prepared at high level of IWG flour (50, 75 and 100%) mixed with wheat flour in order to produce doughs with total fiber content higher than 10%, which is the threshold for significant nutritional benefits from IWG enrichment. Proteins in the various doughs were characterized in terms of solubility, thiols accessibility, and secondary structure as assessed by ATR-FTIR spectroscopy. IWG proteins did not develop into a viscoelastic network as wheat dough (used as a control) did. This behavior was attributed not only to the high fiber content but also to differences in protein profile and secondary structure. Protein characteristics of IWG dough exhibited a large amount of thiols and a network stabilized by non-covalent interactions. In IWG-enriched doughs, as in control dough, beta-sheet represented the predominant secondary structure. However, IWG-enrichment had higher non-sheet/sheet ratio, due to higher amount of unordered structures at the expenses of β-sheet structures. Results indicated that 50% IWG-enrichment represents a good compromise between nutritional improvement and maintenance of protein characteristics in dough. The impact of protein structural characteristics on extensibility and bread-making performances of IWG-enriched doughs needs further investigation
Changes in protein conformation and sulphydryl content in soft and hard wheat flours during mixing
No full textProtein chemical interaction in wheat flour and dough has been a recent subject of research by cereal chemists. This is with the view of possibly understanding the chemical processes and modulating them to deliver desired product attributes. In this study, thiol content and protein secondary structural changes were studied during dough development in two varieties (Branson and TW301020) using 5,5’-dithiobis(2-nitrobenzoic acid) (DTNB) assay and FTIR-ATR spectroscopy. Samples were analyzed at dough development time (DDT), middle of stability (MS), stability departure (SD), and time to break down (TBD). Branson had increased -turns (40 – 48%) and random structures (12 – 14%) with corresponding decrease in α-helix (10 – 8%) and β-sheet structures (38 – 30%) during the mixing period. In TW301020, there were decreases in turns (38 – 34%) and α-helix (11 – 9%) from DDT to TBD and a corresponding increase in random structures (14 – 20%) during mixing, though -sheets stayed essentially the same. Branson therefore exhibited higher level of hydrophobic interactions than TW301020. This is amplified by the very comparable accessible thiols in the two flours (0.373 μmol/g and 0.37μmol/g at SD) but higher total thiols in the Branson (1.06 μmol/g at SD) than TW301020 (0.95 μmol/g at SD) although they show very similar trend along the dough development points
Impact of intermediate wheat grass (Thinopyrum intermedium) on dough rheological properties
No full textIntermediate wheat grass (IWG) (Thinopyrum intermedium) is a perennial grass with desirable agronomic traits and positive effects on environment. Attention is being given to incorporating genetic traits from IWG to common wheat because of its hardness and resistance to wheat diseases. However, the rheological performances of IWG blends with common wheat flour have not been investigated. In this study, IWG was blended with a commercial hard wheat flour (WF) at IWG:WF ratios of 0:100, 50:50, 75:25, 100:0. Mixing properties were evaluated by using a Farinograph. All the dough samples were prepared at constant water absorption (70%) that was optimal for WF to reach 500 BU. Gluten aggregation and pasting properties were also measured by using the GlutoPeak tester (GPT) and the Micro-ViscoAmylograph (MVAG), respectively. Addition of IWG resulted in a decrease in dough development time and an increase in consistency, likely due to the higher levels of fiber in IWG. However, the level of IWG in blends did not result in significant difference in dough development time or consistency. IWG-enrichment resulted in a significant decrease in dough stability, indicating weakening of gluten in the dough. Interestingly, 100% IWG was more stable during mixing compared to 50% or 75% IWG blends, which is probably due to the higher protein content of IWG, although its unclear if this attribute is directly related gluten proteins. Furthermore, GPT highlighted the ability of IWG proteins to aggregate and generate torque. Higher IWG enrichment resulted in faster gluten aggregation, however, with lower peak torque, suggesting weakening of WF gluten strength. MVAG data showed that IWG-enrichment increased the pasting temperature and decreased peak viscosity, probably due to the lower total starch content of IWG compared to WF. Further studies will investigate the suitability of IWG-blends to prepare baked-products with high protein and fiber contents
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