Use of amaranth,quinoa and kañiwa in extruded corn-based snacks

Amaranth (Amaranthus caudatus), quinoa (Chenopodium quinoa) and kañiwa (Chenopodium pallidicaule) are pseudocereals regarded as good gluten-free sources of protein and fiber. A co-rotating twin screw extruder was used to obtain corn-based extrudates containing amaranth/quinoa/kañiwa (20% of solids). Box–Behnken experimental design with three independent variables was used: water content of mass (WCM, 15–19%), screw speed (SS, 200–500 rpm) and temperature of the die (TEM, 150–170 °C). Milled and whole samples were stored in open headspace vials at 11 and 76% relative humidity (RH) for a week before being sealed and stored for 9 weeks in the dark. Hexanal content was determined by using headspace gas chromatography. Extrudates containing amaranth presented the highest sectional expansion index (SEI) (p < 0.01) while pure corn extrudates (control) presented the lowest SEI and greatest hardness (p < 0.01). SEI increased with increasing SS and decreasing WCM. In storage, whole extrudates exposed to 76% RH presented the lowest formation of hexanal. This study proved that it was possible to increase SEI by adding amaranth, quinoa and kañiwa to pure corn flour. The evaluation of lipid oxidation suggested a remarkable stability of whole extrudates after exposure to high RH.     

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

Gluten free (GF) flour (amaranth, buckwheat, chickpea, corn, millet and quinoa) was blended with rice flour to compare their impact on dough rheological characteristics and bread quality. The potential of some GF-rice blends in breadmaking has already been studied on blends with prevailing content of rice flour. The impact of added flour may be expected to rise with increasing amount of flour; therefore blends containing 30 g/100 g, 50 g/100 g and 70 g/100 g of GF flour in 100 g of GF-rice blend were tested. Under uniaxial deformation, peak strain was not impacted by the addition of GF flour; stress (12.3 kPa) was, however, significantly (P < 0.05) decreased (2.9–6.2 kPa). The reduction initiated by the presence of buckwheat, chickpea, quinoa and partly amaranth, together with thermally-induced dough weakening initiated by buckwheat and quinoa flour, may be related to significantly better crumb porosity. Overall acceptability of composite breads containing amaranth, chickpea and quinoa was negatively impacted by the aroma and taste of these flours. Higher potential to improve rice dough behavior and bread quality was found in the blend containing buckwheat flour (30 g/100 g; 50 g/100 g). Millet and corn flour deteriorated dough and bread quality.     

Composition and secondary structure of proteins isolated from six different quinoa varieties from China

Due to its high nutritional value, quinoa has recently been attracting worldwide attention. The composition and secondary structure of proteins isolated from quinoa varieties from other countries have been determined, but proteins from Chinese quinoa varieties have not been described. The aim of this research was to determine the composition and secondary structure of proteins isolated from six different quinoa varieties from China. In all varieties, the protein content was 69.62–73.14%. The fat content and ash content were all less than 2%. The starch content was 20.67–23.12%. The amino acid composition and secondary structures of quinoa protein isolates (QPIs) purified from six Chinese quinoa varieties were investigated by using a combination of amino acid analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and Fourier transform infrared spectroscopy (FTIR). The results revealed that QPIs, with molecular weights ranging from 10.0 kDa to 50.0 kDa, were rich in essential amino acids. In addition, glutamic acid was the most abundant amino acid found in the quinoa protein isolates. The remaining amino acid contents were balanced, except for tryptophan. The secondary structures of QPIs have been quantified by the deconvolution of the amide I band of the FTIR spectrum of QPIs. The main secondary structure in quinoa isolate protein was the β-sheet (from 30.86% to 36.88%). These results will be promising guides for the use of QPIs in food processing and additives.     

In vitro starch digestibility and predicted glycaemic indexes of buckwheat,oat, quinoa,sorghum, teff and commercial gluten-free bread

The in vitro starch digestibility of five gluten-free breads (from buckwheat, oat, quinoa, sorghum or teff flour) was analysed using a multi-enzyme dialysis system. Hydrolysis indexes (HI) and predicted glycaemic indexes (pGI) were calculated from the area under the curve (AUC; g RSR/100g TAC*min) of reducing sugars released (RSR), and related to that of white wheat bread. Total available carbohydrates (TAC; mg/4 g bread “as eaten”) were highest in sorghum (1634 mg) and oat bread (1384 mg). The AUC was highest for quinoa (3260 g RSR), followed by buckwheat (2377 g RSR) and teff bread (2026 g RSR). Quinoa bread showed highest predicted GI (95). GIs of buckwheat (GI 80), teff (74), sorghum (72) and oat (71) breads were significantly lower. Significantly higher gelatinization temperatures in teff (71 °C) and sorghum flour (69 °C) as determined by differential scanning calorimetry (DSC) correlated with lower pGIs (74 and 72). Larger granule diameters in oat (3–10 μm) and sorghum (6–18 μm) in comparison to quinoa (1.3 μm) and buckwheat flour (3–7 μm) as assessed with scanning electron microscopy resulted in lower specific surface area of starch granules. The data is in agreement with predictions that smaller starch granules result in a higher GI.     

Effect of quinoa flour on gluten-free bread batter rheology and bread quality

A new gluten-free bread formulations composed of quinoa, buckwheat, rice flour and potato starch were developed in the present study. Rheological characteristics of the bread batter with increasing amount of quinoa were determined; storage (G′) and loss modulus (G″) values were also measured for investigation of viscoelastic properties. To evaluate the quality of breads; technological and physical (bake loss %, specific volume, texture, microstructure, color), chemical (protein, moisture, ash) and sensory properties were determined. All batter formulations independent of the quinoa amount exhibited pseudoplastic behavior, and G′ values were found to be higher than G″ values in expressing the solid like characteristics of the batter. Amount of quinoa flour addition did not present significant difference on bake loss%, specific volume and protein content (p>0.05); however, 25% quinoa flour bread displayed better results with its higher sensory scores and softer texture. Quinoa and buckwheat flour mixture therefore will be a good alternative for conventional gluten-free bread formulations.     

Physicochemical and functional properties of soluble dietary fiber from different colored quinoa varieties (Chenopodium quinoa Willd)

As it is well documented that the phytochemical composition and bioactive profile of quinoa are influenced by different phenotypes, we analyzed the physicochemical and functional characteristics of different quinoa soluble dietary fiber (SDF). SDF was prepared through ultrasound-assisted enzymatic extraction from three colored quinoa brans. After purification, the yield of SDF from white (W-SDF), red (R-SDF) and black quinoa bran (B-SDF) was 2.2%, 5.7% and 5.9%, respectively. Compared with R-SDF and B-SDF, W-SDF had a higher molecular weight (1.72 × 10⁶ Da) and lower zeta-potential (- 32.16 mV), although their monosaccharide composition and Fourier transform infrared spectroscopy (FT-IR) results showed no obvious differences. The transmission electron microscope (TEM) image suggested that R-SDF exhibited a more complex and loose structure than W-SDF and B-SDF. Moreover, R-SDF exhibited higher thermal stability, gel forming capacity, bile acid binding capacity, water-holding capacity and glucose adsorption capacity than those of B-SDF and W-SDF. Taken together, SDF extracted from quinoa especially from red quinoa might be a promising candidate for the development of novel functional food ingredients.     

In vitro starch digestibility and predicted glycaemic indexes of buckwheat,oat, quinoa,sorghum, teff and commercial gluten-free bread

The in vitro starch digestibility of five gluten-free breads (from buckwheat, oat, quinoa, sorghum or teff flour) was analysed using a multi-enzyme dialysis system. Hydrolysis indexes (HI) and predicted glycaemic indexes (pGI) were calculated from the area under the curve (AUC; g RSR/100g TAC*min) of reducing sugars released (RSR), and related to that of white wheat bread. Total available carbohydrates (TAC; mg/4 g bread “as eaten”) were highest in sorghum (1634 mg) and oat bread (1384 mg). The AUC was highest for quinoa (3260 g RSR), followed by buckwheat (2377 g RSR) and teff bread (2026 g RSR). Quinoa bread showed highest predicted GI (95). GIs of buckwheat (GI 80), teff (74), sorghum (72) and oat (71) breads were significantly lower. Significantly higher gelatinization temperatures in teff (71 °C) and sorghum flour (69 °C) as determined by differential scanning calorimetry (DSC) correlated with lower pGIs (74 and 72). Larger granule diameters in oat (3–10 μm) and sorghum (6–18 μm) in comparison to quinoa (1.3 μm) and buckwheat flour (3–7 μm) as assessed with scanning electron microscopy resulted in lower specific surface area of starch granules. The data is in agreement with predictions that smaller starch granules result in a higher GI.     

Proximate composition and some functional properties of extrusion cooked soybean and sweet potato blends

Mixtures of sweet potato flour and soy flour were made in a pilot mixer. They were moisturized with 18, 25, and 30% water and extruded in a single screw extruder at 80 rpm, using a die of 6mm. Extrusion temperature was maintained at 100 ± 3^°C. Effects of adding soy flour into sweet potato flour, as well as variation in feed moisture on the composition and some functional properties of the extrudates were investigated. Increase in sweet potato content increased carbohydrate values. Protein increased with increase in soy flour. Feed moisture did not significantly ( p 0.05) affect extrudate composition. Increase in sweet potato content and feed moisture increased expansion ratio. Bulk density decreased with decrease in feed moisture, but increased with increase in soy flour. Starch content increased as sweet potato content increased. Degree of gelatinization increased with sweet potato content. Lower feed moisture enhanced gelatinization. Water absorption index (WAI) increased as sweet potato content increased. Feed moisture had a slight effect on WAI and water solubility index (WSI). Amylose increased with increase in sweet potato content. Increase in soy flour led to an increase in yellowness (b^*) of extrudates.     

Agronomical and nutritional evaluation of quinoa seeds (Chenopodium quinoa Willd.) as an ingredient in bread formulations

Quinoa is an Andean seed crop of many potential uses. In 2009 a field trial was carried out to explore the potential for quinoa growing in climatic conditions of South Eastern Europe. Even under rainfed conditions, without fertilization, a seed yield as high as 1.721 t ha⁻¹ was obtained. Seed quality was remarkably good, with protein content ranging from 15.16 to 17.41 % on a dry weight basis, depending on whether seeds were processed. Amino acid and mineral composition revealed the potential of quinoa seeds as a valuable ingredient in the preparation of highly nutritious foods. Quinoa seeds had higher contents of most essential amino acids, especially lysine, than wheat flour. Dehulled quinoa seeds, devoid of saponins, were included into wheat bread formulations, with up to 20%, which resulted in a positive effect on the rheological characteristics of dough. Furthermore, protein content in bread was increased by around 2%. Sensory characteristics of breads were excellent also at the 20% supplementation level. The study of bread supplemented with quinoa seeds could enable the development of a range of new baking products with enhanced nutritional value.     

Effect of arabinoxylans and laccase on batter rheology and quality of yeast-leavened gluten-free breads

The supplementation effects of maize fiber arabinoxylans (MFAX, 0%–6%), laccase (0–2 U/g flour) and water absorption level (90%–100%) on gluten-free (GF) batter rheology and bread quality were analyzed. From viscoamylograph analysis, lower starch amount in GF flour due to MFAX addition decreased peak viscosity and retrogradation. Surface response plots showed that laccase did not have significant effect on GF batter rheology and bread quality, whilst water was the most important variable. Higher levels of water absorption benefited bread texture. Higher water level (>100 mL/100 g flour) was needed in the experimental design to evaluate correctly the effect of 6% MFAX replacement on GF bread quality. Further analyses were carried in order to adjust water absorption of batters according to their consistency index (K ≈ 100 Pa sⁿ), resulting an optimal water absorptions of 95%, 100% and 105% for control flour and flours supplemented with 3% or 6% MFAX, respectively. Thus, MFAX addition enhanced water-binding capacity of flour and yielded GF breads with higher specific volume and softer crumb texture. These quality parameters were best rated with 6% MFAX addition to flours. This research demonstrated the potential of MFAX to develop GF breads with improved quality, when optimal water level is used.     

Effects of selected extrusion parameters on physicochemical properties and in vitro starch digestibility and β-glucan extractability of whole grain oats

Whole grain oat flour was extruded under different moisture contents (15%, 18%, 21%), barrel temperatures (100 °C, 130 °C), and screw speeds (160 rpm, 300 rpm, 450 rpm), and selected physicochemical properties, in vitro starch digestibility, and β-glucan extractability of the extrudates were analyzed. An increase in screw speed resulted in an increase in radial expansion index, water absorption index, and water solubility index. Screw speed significantly affected slowly and rapidly digestible starch. Moderate screw speed (300 rpm) led to higher slowly digestible starch with an accompanying decrease in rapidly digestible starch. Low moisture conditions (15%) resulted in the highest resistant starch and water-extractable β-glucan. Under the conditions used in this study, extrusion did not result in changes in water-extractable β-glucan molecular weight. Thus, extrusion might be beneficial in improving functionality and consumer acceptability by affecting physicochemical properties, in vitro starch digestibility, and β-glucan extractability of oat extrudates.     

Prolonged tempe-type fermentation in order to improve bioactive potential and nutritional parameters of quinoa seeds

The effect of 40 h solid-state fermentation with Rhizopus oligosporus on selected parameters of white and coloured quinoa was studied, as compared to standard (30 h) product and cooked seeds.The reducing power (RP) and the activity against synthetic free radicals of standard tempe were higher by on average 140% (white) and 64% (coloured quinoa) than that of cooked seeds. The OH scavenging activity was increased by more than 7 fold (white), and over 2 fold (coloured quinoa). Prolongation of the fermentation caused further improvement in this potential, on average by 27% (OH, RP) and 24% (DPPH, ABTS⁺ assays). The soluble phenols i.e. vanillic acid, protocatechuic acid and rutin levels in 40 h tempe were significantly higher than in cooked quinoa. Fermented products contained 470% (white) and on average 150% (coloured quinoa) more riboflavin and 100% more thiamine (white quinoa) than cooked seeds. The levels of total protein, free amino acids and proteins releasable during the in vitro digestion, were improved as a result of 40 h fermentation. The essential amino acids profile of quinoa tempe was consistent with the reference pattern.The prolonged tempe-type fermentation of quinoa can be recommended as a method of the value-added food production.     

Enzymatic modification and particle size reduction of wheat bran improves the mechanical properties and structure of bran-enriched expanded extrudates

The aim of this study was to examine enzymatic modification of wheat bran, performed in a low-moisture process, and the reduction of bran particle size as means of improving the technological performance of wheat bran in expanded extrudates. Modification of bran by hydrolytic enzymes increased the crispiness and decreased the hardness and piece density of extrudates containing wheat bran and endosperm rye flour in 20:80 ratio. These improvements correlated (P < 0.01 or 0.05) with an increased content of water extractable arabinoxylan and decreased water holding capacity of the bran, as well as with increased longitudinal expansion of the extrudates. Furthermore, bran with a fine average particle size (84 μm) produced extrudates with improved mechanical properties and higher radial expansion than coarse bran (particle size 702 μm). The impact of bran particle size was also observed in the cellular structure of the extrudates as differences in cell size and homogeneity. The bran drying method, oven or freeze drying after enzymatic modification, did not have a major impact on the properties of the extrudates. The study showed that the functionality of wheat bran in extrusion can be improved by enzymatic modification using a low-water process and by reduction of bran particle size.     

Effects of germination and kilning on the phenolic compounds and nutritional properties of quinoa (Chenopodium quinoa) and kiwicha (Amaranthus caudatus)

Quinoa (Chenopodium quinoa) and kiwicha (Amaranthus caudatus) are nutritious pseudocereals that originate from the Andean region. The aim of this research was to study the effect of germination and the subsequent kilning on the phenolic compounds and proximate composition in selected Peruvian varieties of quinoa (“Chullpi”) and kiwicha (“Oscar Blanco”). The germination process was carried out for 24, 48 and 72 h at 22 °C, and the kilning was performed with samples germinated for 72 h by drying the seeds at 90 °C for 5 min. Both processes increased the protein content of the samples. However, lipid content was reduced during germination. On the other hand, germination and kilning clearly increased the concentration of total phenolic compounds in both quinoa and kiwicha. Germination for 72 h either with or without kilning process resulted in a significant (p < 0.05) increase in the total content of phenolics compared to untreated materials, which was especially due to coumaric acid and a kaempferol tri-glycoside in quinoa and caffeoylquinic acid in kiwicha. Based on the results, germination and kilning may improve the nutritional quality of the Andean grains, encouraging the usage of the processed grains as ingredients in functional products for people with special gluten-free or vegetarian diets.     

Pseudocereals as alternative sources for high folate content in staple foods

Total folate content was determined in the pseudocereals amaranth (four varieties), quinoa and buckwheat in comparison to four cereal species (eight wheat varieties, four barley varieties, one oat variety, one rye variety). Amaranth and quinoa were found to possess very high total folate contents: in amaranth, total folate ranged from 52.8 to 73.0 and in quinoa it was 132.7 μg/100 g dm, about ten times as much as in wheat. The bran fractions contained on average 124% of total folate, while only 57% on average was present in the flour fractions.     

Effect of legume flours on baking characteristics of gluten-free bread

The objective of this work was to study the characteristics of four gluten-free bread formulations and the possibility of substituting soya protein with other legume proteins. Four bread recipes were prepared with chickpea flour, pea isolate, carob germ flour or soya flour. Carob germ flour batter structure was thicker compared with the other batters, probably due to the different protein behaviour and the residual gums present in carob germ flour. However, carob germ flour bread obtained the lowest specific volume values (2.51 cm³/g), while chickpea bread obtained the highest (3.26 cm³/g). Chickpea bread also showed the softest crumb. Confocal scanning-laser microscopy results showed a more compact microstructure in carob germ flour bread compared with soya and chickpea formulations. Chickpea bread exhibited the best physico-chemical characteristics and, in general, good sensory behaviour, indicating that it could be a promising alternative to soya protein.     

The recycling of brewer's processing by-product into ready-to-eat snacks using extrusion technology

Brewer's spent grain (BSG) is the main by-product of the brewing industry. The incorporation of BSG into ready-to-eat expanded products and its effects on the textural and functional properties of extrudates have been studied. Dried and milled BSG at levels of 10–30% was added to the formulation mix made of wheat flour, corn starch and other ingredients. The results obtained from the analysis of the extrudates are discussed in terms of the interaction between the ingredients and effects of processing conditions. The samples were processed in a twin-screw extruder with a combination of parameters including constant feeding rate of 25 kg/h, process temperatures 80–120 °C and screw speeds of 150–350 rpm. Pressure, torque and material temperature during extrusion were recorded. The extrudate properties of nutritional and textural characteristics were measured. Image technique investigations provided useful information on internal structure of the extruded products, total cell area, and their contribution to the appearance and texture. It was found that addition of BSG significantly increased protein content, phytic acid and bulk density, decreased sectional expansion index, individual area and total area of the cells. The higher level of BSG resulted in cells with thicker walls with a rougher surface.     

Quinoa (Chenopodium quinoa Willd.) protein hydrolysates with in vitro dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant properties

The potential of quinoa to act as a source of dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant peptides was studied. A quinoa protein isolate (QPI) with a purity of 40.73 ± 0.90% was prepared. The QPI was hydrolysed at 50 °C for 3 h with two enzyme preparations: papain (P) and a microbial papain-like enzyme (PL) to yield quinoa protein hydrolysates (QPHs). The hydrolysates were evaluated for their DPP-IV inhibitory and oxygen radical absorbance capacity (ORAC) activities. Protein hydrolysis was observed in the QPI control, possibly due to the activity of quinoa endogenous proteinases. The QPI control had significantly higher DPP-IV half maximal inhibitory concentrations (IC₅₀) and lower ORAC values than QPH-P and QPH-PL (P < 0.05). Both QPH-P and QPH-PL had similar DPP-IV IC₅₀ and ORAC values. QPH-P had a DPP-IV IC₅₀ value of 0.88 ± 0.05 mg mL⁻¹ and an ORAC activity of 501.60 ± 77.34 μmol Trolox equivalent (T.E.) g⁻¹. To our understanding, this is the first study demonstrating the in vitro DPP-IV inhibitory properties of quinoa protein hydrolysates. QPHs may have potential as functional ingredients with serum glucose lowering properties.     

Volume and texture improvement of gluten-free bread using quinoa white flour

Patients suffering from coeliac disease have to avoid traditional cereals-based products and depend on the availability of gluten-free alternatives. The gluten-free bread matrix and its foam stability are strongly affected by the choice of ingredients. In this study, the impact of quinoa white flour on bread quality parameters, in particular volume, has been investigated. The pseudocereal proved to be a suitable substrate for dough aeration using yeast, since considerably more glucose and a higher activity of α-glucosidase were found in comparison to rice and corn flour. Consequently, quinoa white flour was used to replace 40–100% of the rice and corn flour in a gluten-free control recipe. As a result, quinoa white flour enhanced the specific volume by 33%, which was related to the absence of bran components and the increased α-glucosidase activity. The significance of the latter was proven by separately adding sucrose and fungal amyloglucosidase to the control recipe. Moreover, the crumb featured homogeneous and finely distributed gas bubbles and the taste was not compromised. Thus, it was possible to improve the quality of gluten-free bread by using quinoa white flour, which might be a relief for coeliac patients.     

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.