Eur Food Res Technol (2010) 230:437–445 DOI 10.1007/s00217-009-1184-z

ORIGINAL PAPER

Baking properties and microstructure of pseudocereal Xours in gluten-free formulations

Laura Alvarez-Jubete · Mark Auty · Elke K. Arendt · Eimear Gallagher

Received: 30 June 2009 / Revised: 22 September 2009 / Accepted: 3 November 2009 / Published online: 25 November 2009 © Springer-Verlag 2009

Abstract In the present study, the baking properties of Introduction the pseudocereals , and as potential healthy and high-quality ingredients in gluten-free To date, the only treatment available for celiac disease is a were investigated. Scanning electron micrographs strict lifelong adhesion to a gluten-free diet [1]. Therefore, were taken of each of the Xours. The pasting properties of celiac patients must avoid the consumption of gluten-con- these Xours were assessed using a rapid visco analyser. taining foods. However, this may prove a diYcult and over- Standard baking tests and texture proWle analysis were whelming task for the celiac patients as the majority of the performed on the gluten-free control and pseudocereal- -based foods available in the market (such as pasta, containing gluten-free breads. Confocal laser scanning baked products, snacks and breakfast ) are prepared microscopy (CLSM) images were also obtained from the with gluten-containing grains, such as [2]. Although baked breads and digital image analysis was conducted on gluten-free alternatives are readily available, Wnding good- the bread slices. Bread volumes were found to signiWcantly quality gluten-free products has been reported as a major increase for the buckwheat and quinoa breads in compari- issue for celiac patients who are trying to adhere to a glu- son with the control. In addition, the pseudocereal-contain- ten-free diet [3, 4]. ing breads were characterised by a signiWcantly softer Despite recent advances in the formulation of high- crumb texture eVect that was attributed to the presence of quality gluten-free products, the replacement of gluten in natural emulsiWers in the pseudocereal Xours and conWrmed cereal-based products, such as bread, biscuit, cake and by the confocal images. No signiWcant diVerences were pasta, still represents a signiWcant technological challenge obtained in the acceptability of the pseudocereal-containing [5]. The formulation of gluten-free breads possibly repre- gluten-free breads in comparison with the control. sents the greatest challenge, due to the fundamental role of gluten in breadmaking [6]. Gluten is an essential struc- Keywords Pseudocereals · Gluten free · Bread · ture-building protein that provides viscoelasticity to the Microscopy · Baking properties · Pasting properties dough, good gas-holding ability and good crumb structure of the resulting baked product [5]. Some of the most important approaches developed to date to mimic the L. Alvarez-Jubete · E. Gallagher (&) Ashtown Food Research Centre, properties of gluten in gluten-free bakery products Teagasc, Ashtown, Dublin 15, Ireland involve the use of gums, hydrocolloids and protein-based e-mail: [email protected] ingredients [6]. Considerably, fewer studies have been dedicated to L. Alvarez-Jubete · E. K. Arendt Department of Food and Nutritional Sciences, improving the nutritional quality of gluten-free products. National University of Ireland, Cork, Ireland Gluten-free cereal foods are frequently made using reWned gluten-free Xour or starch and are generally not enriched or M. Auty fortiWed [7]. As a result, many gluten-free cereal foods do National Food Imaging Centre, W Moorepark Food Research Centre, not contain the same levels of B-vitamins, iron and bre as Teagasc, Moorepark, Fermoy, Co. Cork, Ireland their gluten-containing counterparts [7, 8]. A need to 123 438 Eur Food Res Technol (2010) 230:437–445 improve their nutritional quality has been raised by many Table 1 Bread formulations medical and nutritional experts [2, 9]. Ingredient Gluten-free Amaranth Quinoa Buckwheat Several gluten-free grains exist, such as the pseudocere- (% Xour/ control (A) (Q) (B) als amaranth, quinoa and buckwheat. These seeds are also starch base) (GFC) characterised by an excellent nutrient proWle. Besides being Xour 50 50 50 50 important energy sources due to their starch content, ama- ranth, quinoa and buckwheat provide good-quality protein, Potato starch 50 – – – X dietary Wbre and lipids rich in unsaturated fats [10]. More- Amaranth our – 50 – – X over, they contain adequate levels of important micronutri- Quinoa our – – 50 – X ents, such as minerals and vitamins and signiWcant amounts Buckwheat our – – – 50 of other bioactive components, such as saponins, phytoster- Yeast 3 3 3 3 ols, squalene, fagopyritols and polyphenols [11–14]. A recent Sugar 3 3 3 3 trend by researchers has focused on their use in the formu- Salt 2 2 2 2 lation of high-quality healthy gluten-free products, such as Xanthan gum 0.5 0.5 0.5 0.5 bread and pasta. SunXower oil 6 6 6 6 In a series of recent studies, the nutritional properties Water 87 87 87 87 and baking characteristics of amaranth, quinoa and buck- wheat have been assessed [10, 12, 15]. The authors found that the replacement of potato starch with a pseudocereal were mixed together for 1 min using an A120 Hobart mixer Xour resulted in gluten-free breads with an increased con- (Hobart Food Equipment, Sydney, Australia) at speed 1, tent of important nutrients, such as protein, Wbre, calcium, yeast was dissolved in the water and added to the dry ingre- iron and vitamin E. The resulting breads also had a signiW- dients together with the oil and the batter formed was cantly higher content of polyphenol compounds and their mixed for a further minute. After scraping the base of the in vitro antioxidant activity was increased. bowl, the batter was further mixed for 2 min at speed 2. The In the present study, technological aspects (i.e. batter/ batter was then scaled into baking tins (400 g) and placed in dough and baking properties) related to the application of a proofer (Koma, Roermond, The Netherlands) for 30 min the pseudocereals as ingredients in the production of glu- at 35 °C and 80% relative humidity. The loaves were baked ten-free breads were evaluated. in a deck oven (Tom Chandley Ovens, Manchester, UK) at 220–225 °C for 25 min. They were then cooled to room temperature and stored in polyethylene bags. Six loaves Materials and methods were produced per bake and the preparation of the breads was done in triplicate (i.e. 3 bakes per each type of bread). Bread ingredients pasting properties Amaranth Xour (Ziegler & Co., Wunsiedel, Germany), qui- noa Xour (Ziegler & Co., Wunsiedel, Germany), rice Xour The pasting properties of the Xours and starches were eval- (S&B Herba, Orpington, Kent, UK), potato starch (Healy uated using a Rapid Visco Analyser (RVA, Newport Scien- Chemicals Ltd, Dublin, Ireland), wheat Xour (Odlum tiWc Pty. Ltd, Warriewood, Australia). The method used Group, Dublin, Ireland), sunXower oil (Flora, Liverpool, was the RVA General Pasting Method (Newport ScientiWc UK), xanthan gum (All In All Ingredients, Dublin, Ireland), Pty. Ltd, 1998). fresh yeast (Yeast Product, Dublin, Ireland), salt (Imeos Enterprises, Runcorn, Cheshire, UK) and caster cane sugar Bread evaluation (Tate & Lyle, London, UK) were the materials used in the study. Loaf volume was measured using a volume meter (TexVol BVM-L370, Sweden). Loaf weight was recorded and loaf Preparation of breads speciWc volume (ml/g) calculated. Bake loss deWned as the amount of water and organic material (sugars fermented V The di erent bread formulations are presented in Table 1. and released as CO2) lost during baking was also calculated The amount of water used in the control and in each of ([weight of the loaf before baking ¡ weight of the loaf after the pseudocereal-containing breads was kept the same; the baking and cooling]/[weight of the loaf before baking] £ 100). only diVerence in the formulation of the breads was the Moisture was measured following a procedure based on the type of Xour used as a composite with rice Xour. The glu- ICC method 110.1 [16] using a Brabender moisture oven ten-free batter was prepared as follows: dry ingredients (Brabender, Duisberg, Germany). 123 Eur Food Res Technol (2010) 230:437–445 439

Crust and crumb colour were measured using a Minolta Massachusetts, US). Data were analysed using analysis of Chromameter (Minolta CR-100, Osaka, Japan) and results variance (ANOVA) and the mean were separated by the were expressed using the L*, a*, b* colour scale. Crumb Tukey–Kramer test. DiVerences of p <0.05 were consid- structure of the loaves was evaluated using the C-Cell ered signiWcant. Bread Imaging System (Calibre Control International Ltd., UK). The procedure followed in this study consists of the standardised procedure described by the C-Cell Bread Results Imaging System manufacturer (Calibre Control Interna- tional Ltd., UK). Crumb texture was assessed by conduct- Scanning electron microscopy of the Xours ing a texture proWle analysis (TPA) using a texture analyser (TA-XT2i, Stable Micro Systems, Surrey, UK) equipped SigniWcant diVerences can be observed in the scanning with a 25 Kg load cell and a 36 mm aluminium cylindrical electron micrographs of the pseudocereal Xours, rice Xour, probe. Pre-test, test and post-test speed were 2, 1 and 5 mm/ wheat Xour and potato starch (Fig. 1). In particular, the size s, respectively, and compression was set at 40%. All bread of the Xour particles seems to diVer considerably among the evaluation analysis were conducted 24 h after baking (day Xours under study. Smallest particle size can be observed in 1) and moisture and TPA analysis were repeated 72 and potato starch and wheat Xour, followed by rice, buckwheat, 120 h after baking (days 3 and 5, respectively). amaranth and quinoa Xours. Also, considerable diVerences can be observed in the size and shape of the starch granules. Scanning electron microscopy (SEM) The size of the starch granules in amaranth and quinoa Xours is signiWcantly smaller (<2 m) than in the rest of the Flour samples were sprinkled onto double-sided carbon Xours, and their shape is polygonal. These Wndings are in tape Wxed to an aluminium specimen stub and examined agreement with previously published studies [11, 13, 17]. under high vacuum in a Zeiss Aupra 40VP Weld emission Buckwheat starch granules are also polygonal in shape, scanning electron microscope (Carl Zeiss SMT, Cam- while rice starch granules are irregular in shape and wheat bridge, UK). Secondary electron images were acquired at granules show an oval shape. Potato starch granules are sig- an accelerating voltage of 1 kV. niWcantly larger than in the rest of the Xours, and their shape is oval. Confocal laser scanning microscopy (CLSM) Pasting properties of the Xours Bread samples approximately 5 £ 5 £ 3 mm thick were cut with a razor blade, placed on a microscope slide and 50 ml The results obtained for the pasting properties of rice Xour, of aqueous Nile Blue (0.1% w/w) added to the surface. potato starch and the pseudocereal Xours amaranth, quinoa A coverslip was placed on top and the samples were and buckwheat are summarised in Table 2, and representa- imaged in a Lecia SP5 confocal scanning laser microscope. tive graphs of each Xour are presented in Fig. 2. Dual channel images were acquired with a £63 (1.4 NA) SigniWcant diVerences were observed in the pasting pro- objective, using 488 nm argon ion laser excitation to image Wles of the samples under study. The pasting proWle of potato fat (pseuodocoloured green) and 633 nm helium neon laser starch exhibited high peak viscosity and breakdown and excitation to reveal protein (pseudocoloured bright red) and small setback. These are typical pasting characteristics of gelatinised starch (pseudocoloured dull red). Images, root starches. Peak viscosity diVered signiWcantly among the 512 £ 512 pixels, 8 bit depth were acquired. rice and pseudocereal Xours, and decreased in the order rice > buckwheat > quinoa > amaranth. Breakdown was sig- Sensory analysis niWcantly lower for the pseudocereal Xours compared with rice Xour, which suggests an increased ability of the pseud- Sensory analysis was conducted on all the breads tested by ocereals to withstand heating and shear stress. Highest Wnal a panel consisting in 17 non-celiac consumers. Panellists viscosity was observed for the rice and buckwheat Xours, fol- were asked to assess the breads for acceptability, and to lowed by amaranth and quinoa (p < 0.05). Similarly, setback mark a 6 cm line (0 = unacceptable, 6 = very acceptable) in was highest for rice Xour followed by buckwheat, amaranth accordance with their opinion. and quinoa Xours (p < 0.05). Final viscosity is an important indicator of the strength of the gel formed upon cooling, and Statistical analysis represents an important quality parameter. These Wndings are in agreement with previously published studies [18–20]. Results were analysed using the statistics toolbox of The pasting proWles obtained in the present study for the the software Matlab 7.6 R2008a (Mathworks, Natick, pseudocereal Xours are consistent with previously reported 123 440 Eur Food Res Technol (2010) 230:437–445

Fig. 1 Scanning electron micrographs of amaranth, quinoa, buckwheat and rice Xour, potato starch, and wheat Xour. Scale bars row a 100 m; b 20 m; c 2 m

Table 2 Pasting properties of amaranth, quinoa, buckwheat and rice Xour, and potato starch

PV TV BD FV SB Ptime (min)

Amaranth 273.0 § 2.3 a 225.5 § 1.7 a 47.5 § 0.6 a 321.6 § 2.5 a 96.0 § 0.8 a 5.7 § 0.0 a Quinoa 288.0 § 1.9 b 293.4 § 1.2 b 5.4 § 0.7 b 191.8 § 1.8 b ¡101.6 § 0.5 b 7.0 § 0.0 b Buckwheat 341.4 § 10.6 c 321.0 § 6.9 c 19.9 § 3.2 c 606.5 § 5.7 c 285.1 § 1.6 c 6.4 § 0.1 c Rice Xour 429.6 § 0.1 d 303.1 § 0.6 d 126.5 § 0.4 d 599.0 § 4.6 c 298 § 2.1 d 5.5 § 0.0 d Potato starch 479.2 § 1.8 e 174.9 § 0.2 e 304.2 § 1.5 e 201.7 § 1.2 d 26.7 § 1.0 e 3.4 § 0.0 e W PV peak viscosity, TV trough viscosity, BD breakdown (PV ¡ TV), FV nal viscosity, SB setback (FV ¡ TV), Ptime (min), peak time

values ranging from 3.5 to 19.6% for quinoa starch [18, 19, 22]. The amylose content in amaranth seeds has been reported to be lower than 8% [19, 23]. Contrarily, the con- tent of buckwheat has been reported to be as high as 47% [20], although similar values to those found in other com- mon cereals (25–26%) have also been reported [24].

Bread evaluation

Loaf volume, bake loss and crust/crumb colour

The results for the loaf volume, bake loss (%) and colour of the baked breads are presented in Table 3. The replacement of potato starch by each of the pseudocereal Xours had a variable eVect on loaf volume. Loaf volumes were increased (p < 0.05) for buckwheat (1.63 ml/g) and quinoa (1.4 ml/g) breads in comparison with the control (1.3 ml/g). However, no diVerence in volume was found between the Fig. 2 Pasting proWle of amaranth, quinoa, buckwheat and rice Xour, control breads and those containing amaranth. Bake loss and potato starch diVered slightly between the gluten-free control and the pseudocereal-containing gluten-free breads; however, the levels of amylose in these Xours, and with the small size of diVerences were not signiWcant. their starch granules (see previous section). The amylose In relation to the crust colour of the baked breads, the content of amaranth and quinoa starch is much lower than pseudocereal-containing gluten-free breads were signiW- that found in other cereals [21]. In the case of quinoa starch, cantly darker (lower L* values) compared with the gluten- considerable variability exists within the literature, with free control. The darkening of the crust colour brought 123 Eur Food Res Technol (2010) 230:437–445 441

Table 3 SpeciWc volume (ml/g), bake loss (%), crust L* and crumb L*/b* of the baked breads Bread SpeciWc volume (ml/g) Bake loss (%) Crust L* Crumb L*/b*

Amaranth 1.31 § 0.03 a 9.0 § 0.5 a 56.0 § 1.4 a 3.9 § 0.1 a Quinoa 1.40 § 0.02 b 9.1 § 0.4 a 52.7 § 2.7 a 4.1 § 0.1 a Buckwheat 1.63 § 0.05 c 9.0 § 0.3 a 51.4 § 0.9 a 5.6 § 0.3 b Gluten-free C 1.29 § 0.03 a 9.4 § 0.4 a 69.7 § 1.4 b 6.4 § 0.4 c Mean value of three replicates § SD. Mean values followed by the same letter are not statistically diVerent (p <0.05) about by the replacement of potato starch by a pseudocereal for buckwheat bread followed by quinoa, GFC and ama- Xour is desirable as gluten-free breads tend to have a lighter ranth breads. Smallest cell volume was found in gluten-free crust colour than white wheat breads which sometimes control bread, followed by quinoa, amaranth and buck- appear artiWcial [25]. wheat breads. Cell wall was thinnest in quinoa bread and Crumb colour (L*/b*) (white/yellow ratio) was also increased subsequently in the order quinoa < gluten-free inXuenced and the pseudocereal-containing gluten-free control < buckwheat < amaranth. breads were characterised by a signiWcantly darker crumb colour in comparison with the control. Texture proWle analysis (TPA) of bread crumb

Digital image analysis The results for the TPA analysis of the baked breads, as well as their moisture content, are presented in Fig. 4. The results for the crumb grain analysis of the baked breads All the pseudocereal-containing gluten-free breads had a are summarised in Table 4, and the images obtained are softer crumb in comparison with the gluten-free control, presented in Fig. 3. with amaranth bread having the softest crumb (p < 0.05) Crumb structure diVered signiWcantly in terms of num- over the entire testing period. Overall, a similar trend was ber of cells, cell volume and wall thickness. Crumb grain found in crumb cohesiveness, where all of the pseudoce- represents an important attribute when deWning bread qual- real-containing gluten-free breads had a more cohesive ity [26]. In the present study, largest number of cells was crumb in comparison with the control (p < 0.05). Again, most cohesive crumb was detected in amaranth bread (p < 0.05). Also, all the pseudocereal-containing gluten- Table 4 Crumb structure (digital image analysis) of amaranth, qui- free breads had signiWcantly higher crumb springiness in noa, buckwheat and gluten-free control breads comparison with the control (p < 0.05). Despite the diVer- Bread Number of cells Wall thickness Cell volume ences observed in crumb texture, no signiWcant diVerences were recorded in the moisture content of the bread samples. Amaranth 2,589 § 145 a 0.46 § 0.01 a 21.2 § 1.5 a No studies could be found in the literature to with compare Quinoa 3,176 § 334 b, c 0.42 § 0.02 b 18.7 § 2.7 a, c the TPA results obtained in the present study. Previously Buckwheat 3,340 § 87 b 0.44 § 0.00 b 22.9 § 0.7 b published studies on the baking properties of the pseudoce- Gluten-free 2,992 § 128 c 0.43 § 0.01 b 17.9 § 2.0 c reals focused on their impact on bread volume and sensory control analysis when added at diVerent levels as composites with

Fig. 3 Raw (a) and cell (b) images of amaranth, quinoa, buckwheat and gluten-free control breads

123 442 Eur Food Res Technol (2010) 230:437–445

a 6000 b 0.45 0.4 5000 0.35 4000 0.3 24 h 24 h 0.25 3000 72 h 72 h 0.2 120 h 120 h 2000 0.15 0.1

Crumb hardness (g) 1000

Crumb cohesiveness 0.05 0 0 Amaranth Quinoa Buckwheat GFC Amaranth Quinoa Buckwheat GFC

c 1 d 48.5 0.9 48 0.8 0.7 47.5 0.6 24 h 47 24 h 0.5 72 h 72 h 46.5 0.4 120 h 120 h

0.3 Moisture (%) 46 0.2

Crumb springiness 45.5 0.1 0 45 Amaranth Quinoa Buckwheat GFC Amaranth Quinoa Buckwheat GFC

Fig. 4 Moisture and TPA proWle of the breads after 24, 72 and 120 h post-baking: (a) crumb hardness; (b) crumb cohesiveness; (c) crumb spring- iness; (d) moisture (%). Mean value of three replicates § SD

wheat Xour, and did not measure their impact on the texture Confocal laser scanning microscopy (CLSM) proWle of the resulting breads [27–30]. The eVect of storage time (120 h) on crumb structure The images obtained by confocal laser scanning micros- was also investigated (Fig. 4). Overall, crumb hardness copy of the bread samples are presented in Fig. 5. As increased with storage time. In the case of gluten-free con- expected, signiWcant variation was observed between the trol, amaranth and quinoa breads, the increase in crumb diVerent breads. Starch gelatinisation appears to have hardness with storage time was not signiWcant. For buck- occurred to a greater degree in the gluten-free control bread wheat bread, the increase in crumb hardness was only sig- compared with the pseudocereal-containing gluten-free niWcant after 120 h. In addition, crumb cohesiveness was breads, with starch granules fusing together and losing their found to decrease with storage time for all bread samples original structure. Partial gelatinisation seems to have apart from those containing amaranth. A similar trend was occurred in the pseudocereal-containing gluten-free breads, identiWed for crumb springiness and, although values for and as a result, a greater number of starch granules have this parameter were found to decrease with storage time, retained their integrity. A more homogenous structure is these diVerences were only signiWcant in the gluten-free apparent for the pseudocereal-containing gluten-free control and quinoa breads. Also no signiWcant diVerences breads, with less gas voids and a more even distribution of were recorded in the moisture content of the pseudocereal- fat, protein and starch. Also, the images reveal the impor- containing gluten-free breads during the storage period, tance of the fat globules in forming complexes with starch with the exception of buckwheat bread, the moisture con- granules and/or stabilising gas cells. This eVect appears tent of which decreased signiWcantly after 120 h. These particularly more predominant in the pseudocereal-contain- results suggest that the pseudocereal-containing gluten-free ing gluten-free breads in comparison with the gluten-free products may be used in the production of gluten-free control. breads with a softer crumb structure. This is a desirable characteristic as gluten-free breads are often characterised Sensory analysis by a hard texture [6]. Also the increased cohesiveness and springiness found in the pseudocereal-containing gluten- The acceptability scores of the baked breads as determined free breads can be considered beneWcial, as gluten-free by the taste panellists are displayed in Fig. 6. No signiWcant breads are often characterised by a crumbly, brittle texture diVerences were observed in the acceptability of the baked [31]. breads, showing that pseudocereal Xours may be introduced 123 Eur Food Res Technol (2010) 230:437–445 443

Fig. 5 Confocal laser scanning micrographs of gluten-free control, amaranth, quinoa and buckwheat breads. Scale bars row a 0–250 m; b 0–250 m; c 0–50 m

6 depends on a number of factors, such as viscosity of the batters, amylose/amylopectin ratio, the presence of 5 surface-active components and/or the occurrence of protein aggregation upon heating [32]. In gluten-free breads, the 4 viscosity of the batters prior to starch gelatinisation is cru- cial to prevent the Xour particles from settling and gas cells 3 from rising and thus, maintain a homogenous system dur- ing prooWng and baking until starch gelatinisation [32]. 2 Therefore, factors, such as peak viscosity of the batters seem to have implications in relation to the Wnal quality of 1 the resultant baked bread. In the present study, bread vol- ume of the pseudocereal-containing gluten-free breads was 0 found to increase accordingly with peak viscosity of the Amaranth Quinoa Buckwheat GFC pseudocereal Xour as measured by the rapid visco analyser. Fig. 6 Acceptability scores of baked breads Also, the amylose/amylopectin ratio is a crucial factor determining bread volume and crumb structure as amylose contributes signiWcantly to crumb setting due to its quick into a gluten-free bread formulation to enhance crumb soft- retrogradation rate [32]. As discussed in the previous sec- ness and cohesiveness and without adversely aVecting the tion, the amylose content in amaranth and quinoa Xours is sensory properties of the loaves. lower than in wheat, whereas buckwheat has higher levels of amylose than those found in cereals. These Wndings are consistent with the obtained results in this study: bread vol- Discussion umes and crumb structure were found to improve according to the previously reported amylose contents of the pseud- Some of the more important properties when assessing the ocereal Xours. quality of baked breads are loaf volume and crumb texture. The lipid content and composition in amaranth, quinoa This study showed how bread volume can be signiWcantly and buckwheat seeds may also have implications in relation increased following the incorporation of pseudocereal with functionality during bread making. It has been shown Xours, such as quinoa and buckwheat. The volume of bread that polar lipids naturally present in cereals may contribute 123 444 Eur Food Res Technol (2010) 230:437–445 towards the stabilisation of gas bubbles during bread mak- the formulation of pseudocereal-containing gluten-free ing [32, 33]. The confocal laser scanning micrographs of breads may result in breads with improved crumb structure the baked breads obtained in the present study show that and volume. Also, the pseudocereal-containing breads may lipids in amaranth, quinoa and buckwheat may act as sur- beneWt from higher water levels, especially in the case of face-active agents and thus contribute to gas cell stabilisa- buckwheat and quinoa breads, due to the higher water bind- tion prior to starch gelatinisation. This eVect was ing capacity upon heating of buckwheat and quinoa Xours, particularly relevant in quinoa breads. However, no such as seen in their respective pasting proWles. In addition, ama- eVect was observed in the gluten-free control bread. Lipid ranth and quinoa breads may beneWt from the presence as content in amaranth and quinoa seeds has been reported as composites of gluten-free Xours with high amylose content, being 2–3 times higher than that in buckwheat or in com- such as buckwheat Xour, to compensate for their intrinsic mon cereals, such as wheat [10]. The content of polar lipids low amylose content. Finally, the role of natural emulsiWers in quinoa seeds is very high and represents approximately present in the pseudocereal Xours may have potential in the 25% of total lipids [34]. The polar lipid content in amaranth production of gluten-free breads characterised by an seeds has been reported to be approximately 10% of total improved crumb texture. lipids [35], whereas in buckwheat it ranges between 13.5 The production of high-quality gluten-free breads con- and 15.5% total lipids [36]. Thus, the high level of polar taining pseudocereal Xours would represent a signiWcant lipids in pseudocereal seeds, and in particular in quinoa step towards ensuring an adequate intake of nutrients in seeds, may have functionality as gas cell stabilising agents people with celiac disease. during bread making. Also, the high levels of fats present in amaranth and qui- noa Xours may have implications in relation with both Conclusions crumb structure and crumb texture. The use of emulsiWers in baking has been shown to have a softening eVect on The gluten-free breads containing buckwheat or quinoa Xour bread crumb [37]. Fatty acids from lipid, such as monogly- had a signiWcantly higher volume in comparison with the glu- cerides can form complexes with amylose, thus limiting ten-free control. All the pseudocereal-containing gluten-free starch swelling during baking and leaching of amylose into breads were characterised by a signiWcantly softer crumb. solution [37, 38]. As a result, fewer entanglements between This eVect was attributed to the presence of natural emulsiW- starch granules and amylose in solution take place, leading ers in the pseudocereal Xours and was conWrmed by confocal to breads with a softer crumb structure [32]. Monoglyce- laser scanning microscopy. Results from the sensory panel rides in amaranth Xour have been reported to be in the showed that pseudocereal Xours may be introduced into a range 3.0–3.8% total lipid content [35]. In quinoa seeds gluten-free bread formulation without adversely aVecting the monoglyceride levels are lower (approximately 2%) but the sensory properties of the loaves. The pseudocereal Xours rep- levels of free fatty acids are high (19% total lipid content) resent feasible ingredients in the manufacture of good-qual- [34]. As previously seen, the confocal laser scanning ity, healthy gluten-free breads. micrographs of the pseudocereal-containing baked breads showed fat molecules surrounding starch compounds and Acknowledgment The present study is Wnancially supported by possibly, forming complexes with starch molecules. This Enterprise Ireland. eVect thus, supports the hypothesis that the emulsiWers nat- urally present in the pseudocereal Xours may have a posi- tive eVect, resulting in breads with a softer crumb. References However, as previously discussed, amylose is necessary for good crumb structure, and the presence of emulsiWers may 1. Catassi C, Fasano A (2008) In: Arendt EK, Dal Bello F (eds) Glu- V ten-free cereal products and beverages. Academic Press, London thus have a weakening e ect on crumb structure. The low 2. Kupper C (2005) Dietary guidelines and implementation for celiac levels of amylose in amaranth and quinoa Xour, as well as disease. Gastroenterol 128:S121–S127 the high fat content characteristic of these Xours may be 3. Case S (2005) The gluten-free diet: how to provide eVective edu- responsible for their soft texture, but also for their relatively cation and resources. Gastroenterol 128:S128–S134 4. Pietzak M (2005) Follow-up of patients with celiac disease: weak crumb structure when processed into breads, in com- achieving compliance with treatment. Gastroenterol 128:S135– parison with buckwheat Xour. S141 Other aspects in relation to the functionality of these 5. Gallagher E, Gormley TR, Arendt EK (2004) Recent advances in Xours in gluten-free systems remain to be investigated, such the formulation of gluten-free cereal-based products. Trends Food Sci Technol 15:143–152 as the application of hydrocolloids other than xanthan gum. 6. Arendt EK, Morrisey A, Moore MM, Dal Bello F (2008) In: For example, hydroxypropylmethylcellulose (HPMC) is a Arendt EK, Dal Bello F (eds) Gluten-free cereal products and bev- hydrocolloid with surface-active properties, thus its use in erages. Academic Press, London 123 Eur Food Res Technol (2010) 230:437–445 445

7. Thompson T (1999) Thiamin, riboXavin, and niacin contents of the 22. Wright KH, Huber KC, Fairbanks DJ, Huber CS (2002) Isolation gluten free diet: is there cause for concern? J Am Diet Assoc and characterization of Atriplex hortensis and sweet Chenopodium 99:858–862 quinoa starches. Cereal Chem 79:715–719 8. Thompson T (2000) Folate, Iron, and dietary Wber contents of the 23. Hunjai C, Wansoo K, Malshick S (2004) Properties of Korean gluten-free diet. J Am Diet Assoc 100:1389–1395 Amaranth starch compared to waxy and waxy 9. Thompson T, Dennis M, Higgins LA, Lee AR, Sharrett MK starches. Starch Starke 56:469–477 (2005) Gluten-free diet survey: are Americans with coeliac disease 24. Yoshimoto Y, Egashira T, Hanashiro I, Ohinata H, Takase Y, consuming recommended amounts of Wbre, iron calcium and grain Takeda Y (2004) Molecular structure and some physicochemical foods? J Hum Nutr Diet 18:163–169 properties of buckwheat starches. Cereal Chem 81:515–520 10. Alvarez-Jubete L, Arendt EK, Gallagher E (2009) Nutritive value 25. Gallagher E, Gormley TR, Arendt EK (2003) Crust and crumb and chemical composition of pseudocereals as gluten-free ingredi- characteristics of gluten-free breads. J Food Eng 56:153–161 ents. Int J Food Sci Nutr 60(suppl 4):240–257 26. Scanlon MG, Zghal MC (2001) Bread properties and crumb struc- 11. Berghofer E, Schoenlechner R (2002) In: Belton PS, Taylor JRN ture. Food Res Int 34:841–864 (eds) Pseudocereals and less common cereals: grain properties and 27. Adekunle Ayo J (2001) The eVect of Xour on the utilization potential. Springer, Berlin quality of bread. Int J Food Prop 4:341–351 12. Alvarez-Jubete L, Wijngaard HH, Arendt EK, Gallagher E (2010) 28. Chauhan GS, Zillman RR, Eskin MA (1992) Dough mixing and Polyphenol composition and in vitro antioxidant activity of ama- breadmaking properties of quinoa-wheat Xour blends. Int J Food ranth, quinoa and buckwheat as aVected by and bread Sci Technol 27:701–705 baking. Food Chem 119:770–778 29. Park SH, Morita N (2005) Dough and breadmaking properties of 13. Taylor JRN, Parker ML (2002) In: Belton PS, Taylor JRN (eds) wheat Xour substituted by 10% with germinated quinoa Xour. Pseudocereals and less common cereals: grain properties and uti- Food Sci Technol Int 11:471–476 lization. Springer, Berlin 30. Samiyi M, Ashraf HL (1993) Iranian breads supplemented with 14. Wijngaard HH, Arendt EK (2006) Buckwheat. Cereal Chem amaranth Xour. Int J Food Sci Technol 28:625–628 83:391–401 31. Moore MM, Schober TJ, Dockery P, Arendt EK (2004) Textural 15. Alvarez-Jubete L, Holse M, Hansen A, Arendt EK, Gallagher E comparisons of gluten-free and wheat-based doughs, batters, and (2009) Impact of baking on the vitamin E content of the pseudocere- breads. Cereal Chem 81:567–575 als amaranth, quinoa and buckwheat. Cereal Chem 86(5):511–515 32. Schober T (2009) In: Gallagher E (ed) Gluten-free food science 16. ICC (1976) Standard methods. International Association for Cere- and technology. Wiley-Blackwell, Oxford al Chemistry, Vienna 33. Gan Z, Ellis PR, SchoWeld JD (1995) Gas cell stabilisation and gas 17. Wijngaard HH, Renzetti S, Arendt EK (2007) Microstructure of retention in wheat bread dough. J Cereal Sci 21:215–230 buckwheat and during malting observed by confocal laser 34. Przybylski R, Chauhan GS, Eskin NAM (1994) Characterization scanning microscopy and scanning electron microscopy. J Inst of quinoa (Chenopodium quinoa) lipids. Food Chem 51:187–192 Brew 113:34–41 35. Gamel TH, Mesallam AS, Damir AA, Shekib LA, Linssen JP 18. Lindeboom N, Chang PR, Falk KC, Tyler RT (2005) Characteris- (2007) Characterization of amaranth seed oils. J Food Lipids tics of starch from eight quinoa lines. Cereal Chem 82:216–222 14:323–334 19. Qian J, Kuhn M (1999) Characterization of 36. Mazza G (1988) Lipid content and fatty acid composition of buck- and Chenopodium quinoa starch. Starch Stärke 51:116–120 wheat seed. Cereal Chem 65:122–126 20. Qian J, Rayas-Duarte P, Grant L (1998) Partial characterization of 37. Hoseney RC (1998) Principles of cereal science and technology. buckwheat (Fagopyrum esculentum). Starch Cereal Chem AACC International, St. Paul 75:365–373 38. Belitz HD, Grosch W, Schieberle P (2004) Food chemistry. 21. Schoenlechner R, Siebenhandl S, Berghofer E (2008) In: Arendt Springer, Berlin EK, Dal Bello F (eds) Gluten-free cereal products and beverages. Academic Press, London

123