Amaranth, quinoa and oat doughs: Mechanical and rheological behaviour, polymeric protein size distribution and extractability

https://doi.org/10.1016/j.jfoodeng.2009.07.001Get rights and content

Abstract

The rheological characteristics, static and dynamic mechanical properties of amaranth, quinoa and oat doughs and the relative size distribution of their polymeric proteins were evaluated. For the sake of comparison, semolina dough rheological and mechanical properties and the relative size distribution of proteins were also determined.

From rheological results it was inferred that the tenacity of amaranth, oat and quinoa dough samples was lower than that of semolina dough. The elastic modulus (Ec) of amaranth, oat and quinoa doughs was higher than that of semolina dough. Amaranth and quinoa G′ was found to be similar and significantly higher (p < 0.05) with respect to that of oat dough at a moisture of 30%. The G″ of amaranth, quinoa and oat doughs showed different values. The highest G″ value was recorded for the amaranth dough while the lowest one was shown by oat. For semolina dough, the G′ and G″ values were significantly lower than those of all the other dough samples. Moreover, at low and medium frequencies, tan δ values of oat and quinoa doughs were statistically comparable and significantly lower (p < 0.05) than that of amaranth and semolina doughs. At high frequencies, tan δ values of investigated samples were different among them and the highest value was detected for amaranth, followed by semolina, quinoa and oat. Results of the size distribution of proteins in amaranth, quinoa, oat and semolina doughs were expressed as the proportion of “unextractable polymeric protein” (UPP). Unextractability of semolina dough proteins (61%) was greater with respect to the others, followed by amaranth (40.7%), oat (24%) and quinoa (10.1%).

Introduction

Wheat flour is the only cereal flour that can form a three-dimensional viscoelastic dough when mixed with water. This unique ability of wheat to suit the production of leavened and pasta products is due to the gluten, a cohesive, viscoelastic proteinaceous material prepared as a by-product of starch isolation from wheat flour. The proteins that form gluten are storage proteins which consist of two major fractions: the monomeric gliadins and the polymeric glutenins (Schofield, 1994). The latter are known to be the most important determinants of pasta and bread-making quality (D’Ovidio and Masci, 2004, Lindsay and Skerritt, 1999) and one group of these, of 3–6 proteins, is largely responsible for the elastic properties (Thatam et al., 2001). The high Mr subunits, in fact, possess the characteristics of a putative elastomer, with N- and C-terminal domains containing residues for covalent cross-linking and a central domain that can potentially undergo deformation (Shewry and Thatam, 1990, Belton, 1999). In terms of its nutritional value, gluten (or wheat proteins) is considered to be poorer than proteins from animal sources and can cause allergic reaction and intolerances (Gallagher et al., 2004). Amaranth, quinoa and oat have attracted many interest because of their high nutritional value and for the absence of gluten. In spite of this, the absence of gluten, in these flours, results in major problems for many pasta and bakery products. Their utilization as food ingredients in the production of pasta and bakery products depends largely on their functional properties, which are related to protein structural characteristics. Attempts to use proteins from alternative flours as a partial substitute in wheat products have generally been unsuccessful, because of the contrasting differences between proteins such as the water-solubility, differences in primary structure and their size distributions, accounted for viscoelastic properties that are unique to wheat gluten proteins. Lorimer et al. (1991) reported that the addition of non-gluten forming proteins (e.g. bean-seed proteins) causes a dilution effect and consequent weakening of wheat dough. They suggested several issues that cause weakening, such as competition between legume proteins and gluten for water molecules, the disruption of starch–protein complexes by the foreign proteins and disruption of SS interchange by the non-gluten proteins.

The major seed protein fraction of amaranth, oat and quinoa is represented by globulin, which does not possess the requisites to confer dough elasticity (Belton, 1999, Thatam et al., 2001) and of these only the amaranth one have been extensively studied. Amaranth globulins are composed of 11S-globulin, globulin-P and a small amount of 7S-globulins (Marcone, 1999, Martinez et al., 1997, Segura-Nieto et al., 1994). It was shown that the 11S-globulins have molecular characteristics similar to those of other legumes (Chen and Paredes-Lopez, 1997, Marcone et al., 1994, Marcone et al., 1997, Segura-Nieto et al., 1994). Most of cysteine residues of the globulin-S are involved in disulfide bridges required to maintain the quaternary structure, although their cleavage does not mainly affect the protein secondary structure (Marcone and Yada, 1997). In addition, globulin-P is composed of unitary molecules of molecular weight and polypeptide composition similar to those of 11S-globulin, but it tends to polymerize, thus showing different solubility (Castellani et al., 1998, Martinez et al., 1997). Furthermore, globulin-P molecules have been reported as being composed of dimeric subunits linked by disulfide bonds, since their polymers are stabilized by SS linkages (Martinez et al., 1997). Oat globulins are mainly composed of salt soluble globulin (11S-globulin), and in contrast to other cereals such as wheat, barley and rye, whose storage proteins are generally alcohol soluble prolamins, they represent the major protein fraction. Oat also contains prolamins, called avenins, that account for only 10–15% of total protein, whereas those of wheat, rye and barley account for 40–50%, 30–50% and 35–45% of total protein, respectively (Moulton, 1959, Peterson and Brinegar, 1986).

Quinoa globulins represent ∼77% of total proteins while the percentage of prolamins is low (0.5–0.7%) (Koziol, 1992).

In this type of flours, the absence of gluten represents a formidable challenge to the cereal technologist in pasta products preparation. An effective instrument in predicting the processing behaviour and in controlling the quality of final pasta is the characterization of rheological properties of non-conventional doughs.

Farinograph, mixograph and extensograph are the most common empirical instruments used for characterizing dough rheology. Tests based on these instruments are useful for providing practical information for the pasta industries, while they are not sufficient for interpreting the fundamental behaviour of dough processing and pasta quality. Dynamic rheological testing, especially in the linear viscoelastic region, has been used to follow the structure and properties of doughs and to study the functions of dough ingredients (Janssen et al., 1996, Miller and Hoseney, 1999). This testing simultaneously measures the viscoelastic parameters of dough expressed in storage and loss moduli, G′ and G″, and loss tangent tan δ. It is generally found that doughs made from good quality flour have tan δ values lower than doughs made from poor quality flour. High G′ and G″ values in pasta dough can be related to good structure (Song and Zheng, 2007).

The technological properties of doughs and the quality of the final products are affected by both the modification of polymeric protein size distribution and the protein polymerization through cross-linkage and it is well known that polymers aggregation leads to a significant rise in elastic plateau modulus GN0 of the network (Cornec et al., 1994, Popineau et al., 1994). Two types of polymeric proteins can be separated by their solubility in SDS–phosphate buffer: the soluble fraction and unextractable polymeric proteins (UPP). Only UPP percentage is well correlated with dough strength (Rmax and extensograph tests) and with mixograph peak time (MPT), indicating that the highest polymeric fraction is the major contributing factor to variations in dough properties (MacRitchie and Lafiandra, 1997, Weegels, 1996).

Dynamic rheological and static-mechanical tests are good ways to fundamentally study the changes in product characteristics due to both processing and formulations. Moreover, the dough components (starch, proteins and water) and their interactions play an important role on the conformational structure as well as the rheological properties (Shiau and Yeh, 2001). The dynamic viscoelastic behaviour of doughs can be understood by taking into account the dual role of water that behaves as an inert filler reducing the rheological properties proportionally and as a lubricant enhancing the relaxation (Masi et al., 1998). Starch is able to form a continuous network of particles together with the macromolecular network of hydrated gluten. This interaction gives rise to rheological properties of doughs. Though the interaction plays an important role, the relative contributions of the two sources are difficult to resolve. The component interactions depend on stress level. The starch–starch interactions dominate over protein–protein interactions at low stresses, while the protein–protein interactions play a dominant role at large deformations (Khatkar and Schofield, 2002). Gluten contributes to the viscoelastic properties of dough to varying degrees depending on its source differing with both gliadin/glutenin ratio and LMW–GS (Edwards et al., 2001, Edwards et al., 2003). Gliadin enhances viscous flow of dough. Glutenin addition results in a more elastic dough in comparison with gluten and gliadin additions (Edwards et al., 2001). Increasing the glutenin/gliadin ratio improves maximum shear viscosity and dough strength (Uthayakumaran et al., 2000).

At our knowledge there are no works about the influence on the rheology of proteins different from gluten.

The aim of this work was to study the rheological characteristics of amaranth, quinoa and oat crumbly dough for pasta making. In addition, the molecular size distribution of the non-conventional dough polymeric proteins and their extractability were also evaluated.

Section snippets

Materials and preparation of dough samples

Amaranth, quinoa, oat wholemeal flours and semolina were purchased from Bongiovanni Mill (Molino Bongiovanni, Mondovì, Cuneo, Italy). For each flour, 300 g of dough crumbly samples were prepared using ordinary tap water and a fresh pasta home appliance (Pastamatic, Simac 1400N, Treviso, Italy). The kneading time was 15 min for non-conventional dough samples and 20 min for semolina ones. The water added to non-conventional flours and semolina to prepare dough samples was of 30% (Chillo et al., 2008

Chemical analysis

The flours examined had very similar protein content while significant differences could be detected for the ash and total fiber content (Table 1). The lowest ash content value was recorded for semolina sample (0.68%) while the highest were shown by amaranth (2.38%) and quinoa (2.17%) flours. On the contrary, oat flour showed the highest total fiber content (11.33%) followed by quinoa (9.86%), amaranth (8.83%) and semolina (3.8%) samples.

Static and dynamic mechanical properties

Fig. 1 reports the stress–strain curves for amaranth,

Conclusion

The tenacity of amaranth, oat and quinoa doughs was lower than that of semolina dough sample. The elastic modulus of amaranth, oat and quinoa dough samples was higher than that of semolina dough. The G′ values of amaranth and quinoa were similar but significantly higher (p < 0.05) respect to that of oat dough. G″ for the three non-conventional doughs showed different values: the highest was recorded for the amaranth dough while the lowest was shown by oat. The semolina dough showed G′ and G

Acknowledgement

This research work was financially support by Italian Puglia Region, Strategic Project “Process innovation for production of functional pasta”, PS_003.

References (68)

  • A.M. Janssen et al.

    Fundamental and empirical rheological behavior of wheat flour doughs and comparison with bread making performance

    Journal of Cereal Science

    (1996)
  • M.J. Koziol

    Chemical composition and nutritional evaluation of quinoa (Chenopodium quinoa Willd)

    Journal of Food and Compositional Analysis

    (1992)
  • M.P. Lindsay et al.

    The glutenin macropolymer of wheat flour doughs: structure–function perspective

    Trends in Food Science and Technology

    (1999)
  • M. Mancini et al.

    Mechanical properties of alginate gels: empirical characterization

    Journal of Food Engineering

    (1999)
  • M.F. Marcone

    Evidence confirming the exsistence of a 7S globulin-like storage protein in Amaranthus hypocondriacus seed

    Food Chemistry

    (1999)
  • Y. Popineau et al.

    Influence of high Mr glutenin subunits on glutenin polymers and rheological properties of glutens and gluten subfractions of near-isogenic lines of wheat sicco

    Journal of Cereal Science

    (1994)
  • V.K. Rao et al.

    Rheological characterization of long- and short-mixing flours based on stress–relaxation

    Journal of Cereal Science

    (2000)
  • L. Rhazi et al.

    Changes in the glutathione thiol-disulphide status during wheat grain development

    Plant Physiology and Chemistry

    (2003)
  • R.K. Richardson et al.

    Characterisation of the perceived texture of the thickened systems by dynamic viscosity measurements

    Food Hydrocolloids

    (1989)
  • S.B. Ross-Murphy

    Small deformation measurements

  • P.R. Shewry et al.

    Structure, assembly and targeting of wheat storage proteins

    Journal of Plant Physiology

    (1995)
  • S.Y. Shiau et al.

    Effect of alkali and acid on dough rheologicsl properties and characteristics of extruded noodles

    Journal of Cereal Science

    (2001)
  • Y. Song et al.

    Dynamic rheological properties of wheat flour dough and proteins

    Trends in Food Science and Technology

    (2007)
  • K. Thorvaldsson et al.

    Rheology and structure of heat-treated pasta dough: influence of water content and heating rate

    Lebensmittel-Wissenschaft und -TechnologieLebnsm

    (1999)
  • P. Weegels

    Functional properties of wheat glutenin

    Journal of Cereal Science

    (1996)
  • T. Aussenac et al.

    Change in SDS-solubility of glutenin polymers during dough mixing and resting

    Cereal Chemistry

    (2001)
  • J.A. Bietz et al.

    Wheat glutenin subunits: molecular weights determined by sodium dodecylsulphate–polyacrylamide gel electrophoresis

    Cereal Chemistry

    (1972)
  • J.L. Carceller et al.

    SDS-insoluble glutenin polymer formation in developing grains of hexaploid wheat: the role of the ratio of high to low molecular weight glutenin subunits and drying rate during ripening

    Australian Journal of Plant Physiology

    (2001)
  • O. Castellani et al.

    Structural modifications of amaranth globulin induced by pH and NaCl

    Journal of Agricultural and Food Chemistry

    (1998)
  • S. Chen et al.

    Isolation and characterization of the 11S globulin from amaranth seeds

    Journal of Food Biochemistry

    (1997)
  • Edwards, N.M., Dexter, J.E., Scanlon, M.G., 2001. The use of rheological techniques to elucidate durum wheat dough...
  • N.M. Edwards et al.

    Relationship of creep-recovery and dynamic oscillatory measurements to durum wheat physical dough properties

    Cereal Chemistry

    (1999)
  • N.M. Edwards et al.

    Role of gluten and its components in determining durum semolina dough viscoelastic properties

    Cereal Chemistry

    (2003)
  • C. Fares et al.

    Processing and cooking effects on chemical, nutritional and functional properties of pasta obtained from selected emmer genotypes

    Journal of the Science of Food and Agriculture

    (2008)
  • Cited by (22)

    • Non-targeted metabolomics of quinoa seed filling period based on liquid chromatography-mass spectrometry

      2020, Food Research International
      Citation Excerpt :

      The United Nations Food and Agriculture Organization regards quinoa as the only plant that can satisfy the basic nutritional needs of humans. Quinoa is low in sugar and calories but high in nutritional value (Bhargava, Shukla, & Ohri, 2006; Lamacchia et al., 2010), proteins, amino acids (Comai et al., 2007), flavonoids (Dayana, Ivon, Ricardo, & Ericsson, 2019; Repo-Carrasco-Valencia, Hellström, Pihlava, & Mattila, 2010), and minerals (Ogungbenle, 2003). Studies have shown that quinoa extract can delay the aging of nematodes (Brittany et al., 2017), and the consumption of quinoa has been shown inhibit the dysregulation of intestinal microbiota, thus improving intestinal health (Liu et al., 2018).

    • Protein and antioxidant composition of quinoa (Chenopodium quinoa Willd.) sprout from seeds submitted to water stress, salinity and light conditions

      2017, Industrial Crops and Products
      Citation Excerpt :

      Probably, the washing process resulted in the removal or damage of the external endosperm, losing some proteins in water. The amount of albumins and globulins extracted from ground seeds (Table 2) is similar to that reported by Drzewiecki et al. (2003), and Lamacchia et al. (2010), who have indicated that quinoa seeds contain mostly albumins (31%) and globulins (37%), while Koziol (1992) described that the concentration of prolamins is low (0.5–0.7%). Between 21 and 25 albumins bands were observed in samples from washed seeds, while this number ranged between 8 and 11 in unwashed seeds, (Fig. 1).

    • The comparison of the effect of added amaranth, buckwheat, chickpea, corn, millet and quinoa flour on rice dough rheological characteristics, textural and sensory quality of bread

      2017, Journal of Cereal Science
      Citation Excerpt :

      GF doughs exhibit high viscous and elastic moduli are higher. Finally, GF dough viscosity during baking is not optimal (Burešová et al., 2014; Gujral and Rosell, 2004; Lamacchia et al., 2010). All these factors significantly impact dough ability to trap leavening gas, resulting in low GF bread volume, crumbly texture, crumb hardness, poor color, reduced shelf life and other quality defects (Anton and Artfield, 2008; Gallagher et al., 2004; Hager et al., 2012; Sivaramakrishnan et al., 2004).

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

      2017, Journal of Cereal Science
      Citation Excerpt :

      The gels were stained with 0.25% w/v Coomassie Brilliant Blue (CBB) overnight. Proteins from semolina, einkorn flour and milled macaroni were extracted following the method of Gupta et al. (1993) and Lamacchia et al. (2010). SE-HPLC was performed using a liquid chromatograph Agilent 1100 Series system (Santa Clara, CA, USA) equipped with a Phenomenex Biosep SEC-S4000 column (300 × 7.8 mm, Phenomenex, Torrance, CA, USA).

    • Interpretation of mechanical spectra of carob fibre and oat wholemeal-enriched wheat dough using non-linear regression models

      2011, Journal of Food Engineering
      Citation Excerpt :

      So far this kind of approach has never been used in the interpretation of oscillation measurements. Experimenters performed analyses of dynamic moduli measured at a single selected frequency, e.g., 1 Hz (Van Bockstaele et al., 2008b), or after averaging data if the data had been collected at various frequencies (Pedersen et al., 2004), or else using subjective visual interpretation of curves plotted in a graph (Lazaridou et al., 2007; Leray et al., 2010; Skendi et al., 2009; Lamacchia et al., 2010; Stojceska et al., 2007). Therefore, the mechanical spectra were usually characterised in an arbitrary manner, without getting involved in any quantitative description of the runs of those relations.

    • Influence of extruded whole wheat flour addition on quality characteristics of pasta

      2024, International Journal of Food Science and Technology
    View all citing articles on Scopus
    View full text