Functional properties of tortillas with triticale flour as a partial substitute of nixtamalized corn flour

The effect of partial substitution of nixtamalized corn flour for triticale flour in functional properties of dough and tortillas was evaluated. Seven blends of refined triticale and nixtamalized corn flour (NCF) were tested in a traditional process of tortilla production. Triticale flour significantly reduced water absorption of dough, tortillas cooking time and yield. NCF-Triticale flour blends for making tortillas using water to 80 °C improves the consistency and cohesiveness of dough. A mix containing more than 25 g of triticale flour per 100 g of flour develop inadequate adhesiveness of the dough, which is inconvenient when using the manual press. The extensibility of tortilla blends was lower than pure NCF tortillas. The advisable proportion for triticale flour used as a partial substitute of nixtamalized corn flour was 100 g kg⁻¹ (flavor, color, texture and an acceptable adhesiveness).     

Physicochemical characterization of corn–sorghum nixtamalized flours as a function of the steeping time

This work focused on the study of the physicochemical properties of nixtamalized corn and sorghum flours, as well as combined nixtamalized corn–sorghum flours with 10, 20, and 30 % of sorghum. The removal of the sorghum pericarp during nixtamalization depends on the steeping time and strongly influences the water and calcium uptake. The absence of the waxy layer in sorghum grain allows a faster water uptake in relation to corn grain. Changes in the pericarp structure during the steeping time govern the Ca absorption in sorghum grain. The partial removal of the pericarp and the most external layers of the endosperm produce the decrease in phosphorous content for corn and sorghum. The Ca/P ratio of nixtamalized corn/sorghum flours is greater than 1 for steeping time up to 3 h. Therefore, this fact could help the increase of Ca in the daily diet. Amylopectin is the predominant macromolecule in both starches. The pasting profiles showed a decrease in peak viscosity when the sorghum fraction increases; this is due to increases in fiber.     

A comparison of the quality of whole corn tortillas made from instant corn flours by traditional or extrusion processing

Summary The nutritional quality (chemical and biological assays) was evaluated for tortillas made with two samples of instant corn flour prepared with 0.15 and 0.25% calcium hydroxide and processed either by extrusion or by the traditional process (nixtamalization). Both raw corn and the tortillas made from instant whole corn flours prepared by extrusion (TEP) had higher Protein Efficiency Ratio (PER), and Net Protein Utilization (NPU) values ( p < 0.05) than tortillas prepared from traditional nixtamalization process. The Ca assimilation in the femurs bones of rats fed with raw corn, TEP (with 0.25% lime), and tortillas prepared from the nixtamal process, yielded lower values ( p < 0.05) as compared with those shown by the rats fed with the other treatments of TEP (with 0.15% lime). The Ca, Mg, and P contents and protein quality of the treatments used in the feed affected some physical characteristics rat femurs (length, diameter, weight, breaking force, volume and density). The force required to break the femurs of rats fed diets of raw corn, tortillas prepared using the traditional process and without added protein, was measured and compared with the force required to break the femurs of rats fed with diets contain casein and TEP with either 0.15 and 0 0.25% lime. Those animals assimilating the lowest content of lime had the weakest femurs.     

Simplex lattice mixture design approach on physicochemical and sensory properties of wheat chips enriched with different legume flours: An optimization study based on sensory properties

In this study, physicochemical and sensory characteristics of wheat chips enriched with different legume flours were investigated. Wheat chips formulations were composed with the mixture of wheat flour and the mixture of three different legume flours (wheat–legume ratio 80:20). Mixture design approach was used to determine the effect of interactions between pea, chickpea and soy flour on the physicochemical and sensory properties of chips produced with wheat–legume flour mixture. In addition, product optimization was carried out by using ridge analysis to determine the optimum legume flour mixture proportions based on sensory properties of chips samples. Chickpea flour was found to be highest desired component depending on the general acceptability scores of chips. Protein content of chips increased significantly with the addition of soy flour. Optimum limit values of chickpea, pea and soy flour in the legume flour mixture used for the enrichment of the wheat chips were found to be 50–100 g/100 g, 0–60 g/100 g and 0–45 g/100 g legume flour, respectively, with respect to sensory properties. Additionally, ridge analysis results showed that the wheat chips should include only chickpea flour in the legume flour fraction to obtain maximum overall preference score (6.08).     

Instant flour from quality protein maize (Zea mays L). Optimization of extrusion process

Traditional nixtamalization process for producing instant flours is highly time and energy consuming; in addition, it presents problems of high liquid waste discharges (3–10 L H₂O/kg maize). Extrusion represents an alternative technological for producing instant flours and does not generate effluents. The objective of this work was to determine the best combination of extrusion process variables for the production of instant flour from quality protein maize (QPM) (Zea mays L) V537 variety. Prior to extrusion, the maize kernels were broken to obtain grits (1−2 mm) which were mixed with lime and water to reach a moisture content of 28 g/100 g. The single screw extruder operation conditions were selected from a factorial combination of process variables: extrusion temperature (ET, 70–100°C), lime concentration (LC, 0.1–0.3 g/100 g maize) and screw velocity (SV, 30–80 rpm). A central composite experimental design with five variation levels was chosen. Response surface methodology was applied as optimization technique, over four response variables: in vitro protein digestibility (PD), total color difference (ΔE), water absorption index (WAI) and pH. Predictive models for response variables were developed as a function of process variables. The conventional graphical method was applied to obtain maximum PD, WAI, pH and minimum ΔE. Contour plots of each of the response variables were utilized applying superposition surface methodology, to obtain three contour plots for observation and selection of a superior (optimum) combination of ET (79.4°C), LC (0.24 g/100 g maize) and SV (73.5 rpm) to obtain optimized extruded maize flour (EMF) from QPM with a single screw extruder. Optimized EMF had similar physico-chemical and functional characteristics than commercial nixtamalized maize flours (NMF).     

Study of the physicochemical and pasting properties of instant corn flour added with calcium and fibers from nopal powder

This work presents a physicochemical and apparent viscosity characterization of commercial nixtamalized corn flours (CNCF) added with nopal powder. The chemical proximate analysis of CNCF and traditional nixtamalized corn flours (TNCF) shows equal amounts of protein and fat, but the calcium content and total dietary fiber is higher in the TNCF. Nopal powder contains a high amount of Ca, soluble and insoluble fiber. The inclusion of 4% of nopal powder increases the calcium and fiber content of the CNCF to the level of traditional nixtamalized products steeped at 7 h. A pasting characteristics analysis based on the profile curves was done in order to study the influence of soluble and insoluble fibers on the pasting conditions of the studied samples added with nopal. At low temperatures the insoluble fiber governs the water absorption and below the gelatinization temperature (T_g) a competition between starch swelling and water absorption was found; for T higher than T_g the system is complex because it includes the interactions between soluble–insoluble fibers and exuding amylose.     

Effects of common bean enrichment on nutritional quality of tortillas produced from nixtamalized regular and quality protein maize flours

In Mexico the tortilla is most commonly eaten in the form of ‘taco’; this is normally accompanied with other food, in particular the common bean. Tortillas made of quality protein maize (QPM) fortified with common bean might be a strategy to improve their protein quality. In this study, amino acids and mineral changes that occur during nixtamalization and the chemical and nutritional characteristics of regular, commercial and QPM tortilla–bean combination were assessed. After nixtamalization, protein from QPM nixtamalized maize flour was reduced from 8.1% to 7.2% (w/w). Tryptophan was also reduced from 12.1 to 11.1 g kg^?1 protein. QPM maize retained a higher amount (P < 0.05) of calcium (3180 mg kg^?1) compared to regular maize (1820 mg kg^?1). When nixtamalized maize flour of regular maize and commercial tortilla were combined with beans, protein content increased. The tryptophan and lysine contents in these tortillas were increased (P > 0.05) also, but were significantly lower (P > 0.05) than in tortilla made with QPM maize fortified with bean (22.7 and 69.9 g kg^?1 protein, respectively). Mineral contents increased in tortilla–bean combination. The QPM and tortilla fortified with bean gave an improvement in protein quality and could contribute significantly towards human nutrition, especially in countries like Mexico where maize and beans are important components of the diet. Copyright © 2007 Society of Chemical Industry     

Mitigating effect of amaranth (Amarantus hypochondriacus) protein on acrylamide formation in foods

The effect of addition of amaranth flour and amaranth protein isolate to both a glucose/asparagine model system and real foods (cookies, fried tortilla chips, and baked tortilla chips) was studied to analyse the acrylamide mitigating potential of this underexploited plant with attractive nutraceutical properties. Addition of amaranth flour, with a relatively low protein content (16.45%), did not mitigate acrylamide in either the model system or the studied foods. On the contrary, addition of amaranth protein isolate decreased acrylamide content by 35–40% in the model system, 89% in cookies, 51% in fried tortilla chips, and 62% in baked tortilla chips. This acrylamide reduction was obtained without change in the colour or the texture of the cookies. On the contrary, colour remained unchanged in tortilla chips, but the addition of amaranth protein isolate increased the hardness (16–36%) of the produced tortillas. Although a much more detailed sensory evaluation of cookies and tortilla chips prepared using amaranth protein isolate is needed, the above results suggest that the use of amaranth protein may be an interesting way to both mitigate acrylamide formation and improve nutritional properties of foods.     

The optimization of the extrusion process when using maize flour with a modified amino acid profile for making tortillas

Maize with a modified amino acid profile, i.e. greater amounts of lysine and tryptophan than normal, is known as ‘quality protein maize’ (QPM). The objective of this work was to find the best combination of extrusion process variables to produce QPM flour for making tortillas. QPM grits were mixed with lime and water and had a moisture content of 28%. The single screw extruder operation conditions were selected from factorial combination of three process variables: extrusion temperature (ET, 70–100 °C), lime concentration (LC, 0.1–0.3% of the maize weight) and screw velocity (SV, 80–250 rpm). Response surface methodology was used as an optimization technique. In vitro protein digestibility (PD); total colour difference (ΔE) of the flours, and tortilla puffing (TP) were chosen as response variables. A graphical method was used to obtain maximum PD, TP and minimum ΔE. The optimum combination of process variables was: ET = 85 °C/LC = 0.21%(w/w)/SV = 240 rpm. Tortillas from QPM flour had similar chemical composition, physicochemical and sensory properties to tortillas from commercial nixtamalized maize flour; however, the former had the highest (P ≤ 0.05) available lysine content and were therefore better nutritionally.     

Comparison of methods and optimisation of the analysis of fumonisins B1 and B2 in masa flour,an alkaline cooked corn product

A comparison study of different extraction and clean-up procedures for the liquid chromatographic analysis of fumonisins B₁ (FB₁) and B₂ (FB₂) in corn masa flour was performed. The procedures included extraction (heat or room temperature) with acidic conditions or EDTA-containing solvents, and clean-up by immunoaffinity or C18 solid-phase extraction columns. Thereafter an analytical method was optimised using extraction with an acidic mixture of methanol–acetonitrile–citrate/phosphate buffer, clean-up through the immunoaffinity column and determination of fumonisins by liquid chromatography with automated pre-column derivatisation with o-phthaldialdehyde reagent. Recovery experiments performed on yellow, white and blue masa flours at spiking levels of 400, 800 and 1200?µg?kg^?1 FB₁ and of 100, 200 and 300?µg?kg^?1 FB₂ gave overall mean recoveries of 99% (±6%) for FB₁ and 88% (±6%) for FB₂. Good recoveries (higher than 90% for both FB₁ and FB₂) were also obtained with corn tortilla chips. The limits of quantification of the method (signal-to-noise ratio of 10) were 25?µg?kg^?1 for FB₁ and 17?µg?kg^?1 for FB₂. The method was tested on different commercial corn masa flours as well as on white and yellow corn tortilla chips, showing fumonisin contamination levels (FB₁?+?FB₂) up to 1800?µg?kg^?1 (FB₁?+?FB₂) in masa flour and 960?µg?kg^?1 in tortilla chips. Over 30% of masa flours originating from Mexico exceeded the European Union maximum permitted level.     

Kinetics of water diffusion in corn grain during the alkaline cooking at different temperatures and calcium hydroxide concentration

The kinetics of corn grains hydration during the nixtamalization process is described for different temperatures, cooking times and Ca(OH)₂ concentrations. Samples were prepared using different cooking times from 0 to 120 min; cooking temperatures of 62, 72, 82, and 92 °C, and Ca(OH)₂ concentrations of 0.0%, 0.8%, 1.0%, and 2.0% related to the mass of corn grains. The fitting of the experimental data to the empirical Michaelis-Menten equation gives a good approach of the hydration process. From the first derivate of the Michaelis-Menten equation the rate of the corn grain hydration can be obtained. This mathematical model predicts the hydration and hydration rate of the corn grains during the cooking time of the nixtamalization process. Furthermore, with this proposed model, we can predict that for short times the rate reaches its maximum, and tends to zero for long times as the saturation of the grain is reached. It is concluded that hydration and hydration rate of white corn grains depends significantly on the temperature and cooking water lime concentration (P < 0.005).     

Physicochemical properties of rice flour as affected by alkaline soaking and washing treatments

Effects of alkaline [NaOH, saturated Ca(OH)₂ and/or limewater] soaking and subsequent washing (with water vs. without washing) treatments on physicochemical properties of rice flour were investigated. Alkaline soaking treatment generally caused a loss of granule angularity but some birefringence was observed for unwashed alkali-soaked flour granules. After soaking, protein content of the flours significantly (P < 0.05) decreased but swelling power significantly (P < 0.05) increased compared to the control (soaked in water). The washed flours had lower protein content than unwashed flours (3.77–6.87% vs. 5.26–7.87%). The NaOH-soaking treatment yielded higher swelling power and solubility, respectively, for unwashed and washed flours. Alkaline soaking increased breakdown but decreased pasting temperature, trough viscosity, final viscosity and setback of the paste compared to the control. Compared to the control, hardness of soaked flour paste was lower due to lower final viscosity and setback. Overall, physicochemical properties of rice flour could be modified by alkali-soaking and washing treatments.     

Effect of calcium content in the corn flour on RVA profiles

Corn flour was produced using the traditional nixtamalization process and different steeping times of 0, 1, 5, 6, 10, 13, and 24 h. The flour particle size distribution was then evaluated in terms of the particles retained by using a 40 US mesh screen. The lime content, the Rapid Visco Analyzer (RVA) profiles, maximum peak viscosity, breakdown and final viscosity (V) were measured as a function of the steeping time. It was found that the initial rate of increase in viscosity (dV/dt), maximum peak viscosity, breakdown and final viscosity of fractions depended on the amount of calcium incorporated in the corn kernels during the steeping time (T_s) of the nixtamalization process. The particles retained using a 40 mesh that were steeped for 0-5 h, do not have the characteristic points of an RVA profile, i.e., maximum peak viscosity and breakdown. However, the particles retained using a 40 mesh and steeped for 6-24 h developed peak viscosity, breakdown and final viscosity. The corn flours that are recommended for making tortillas are precisely the flours whose particle size distributions develop these three characteristic points in the RVA profile. Differences in RVA measurements of the size fractions can be explained on the basis of the calcium content of the course fractions of corn flours. It was concluded that RVA characteristics may be changed by the calcium content in the starch polymer structures created during the nixtamalization process. Consequently, the increased calcium content in starch particles should be reflected in RVA measurements as an increase in the peak viscosity, in the gelatinization rate and in the development of a noticeable breakdown.     

Physicochemical and Morphological Characteristics of Nixtamalized Maize Starch

The effect of nixtamalization on physicochemical and morphological characteristics of starch was studied. Determination of total starch, ash and amylose content, of swelling and solubility, gelatinization characteristics and morphological studies were carried out in starch isolated from native (S) and nixtamalized (NS) maize flours. Thermal analysis showed that nixtamalization produced starch annealing due to the higher gelatinization temperature obtained for NS. However, S had slightly lower enthalpy values. The swelling profile was similar for both starches, but the solubility values at the temperatures assessed were slightly higher in the NS samples. At temperatures below gelatinization, the granules showed the Maltese cross while at higher temperatures only ghost of granules were observed. The nixtamalized starch had larger granule sizes than the native starch, due to the partial swelling produced in the heating during the nixtamalization process. Larger granule sizes were also observed by image analysis, because major axis and area parameters were higher in NS samples than in S samples. The nixtamalization process produced changes in chemical, thermal and morphological characteristics, becoming important in products obtained from nixtamalized maize.     

Comparison of methods and optimisation of the analysis of fumonisins B₁ and B₂ in masa flour, an alkaline cooked corn product

A comparison study of different extraction and clean-up procedures for the liquid chromatographic analysis of fumonisins B(1) (FB(1)) and B(2) (FB(2)) in corn masa flour was performed. The procedures included extraction (heat or room temperature) with acidic conditions or EDTA-containing solvents, and clean-up by immunoaffinity or C18 solid-phase extraction columns. Thereafter an analytical method was optimised using extraction with an acidic mixture of methanol-acetonitrile-citrate/phosphate buffer, clean-up through the immunoaffinity column and determination of fumonisins by liquid chromatography with automated pre-column derivatisation with o-phthaldialdehyde reagent. Recovery experiments performed on yellow, white and blue masa flours at spiking levels of 400, 800 and 1200 μg kg(-1) FB(1) and of 100, 200 and 300 μg kg(-1) FB(2) gave overall mean recoveries of 99% (±6%) for FB(1) and 88% (±6%) for FB(2). Good recoveries (higher than 90% for both FB(1) and FB(2)) were also obtained with corn tortilla chips. The limits of quantification of the method (signal-to-noise ratio of 10) were 25 μg kg(-1) for FB(1) and 17 μg kg(-1) for FB(2). The method was tested on different commercial corn masa flours as well as on white and yellow corn tortilla chips, showing fumonisin contamination levels (FB(1) + FB(2)) up to 1800 μg kg(-1) (FB(1) + FB(2)) in masa flour and 960 μg kg(-1) in tortilla chips. Over 30% of masa flours originating from Mexico exceeded the European Union maximum permitted level.     

Proximal composition and in vitro starch digestibility in flaxseed‐added corn tortilla

BACKGROUND: The effect of addition of flaxseed flour (10:90, 15:85 and 20:80, w/w) on the chemical composition and starch digestibility of corn tortilla was investigated. Tortillas were baked and frozen in liquid nitrogen, freeze‐dried, ground and analyzed for fat, protein, ash, total starch (TS), available starch (AS) and resistant starch (RS) contents as well as for starch hydrolysis rate and predicted glycemic index (pGI). Tortillas made from commercial nixtamalized corn flour were used as control sample. RESULTS: Flaxseed flour addition increased the fat and protein content of tortilla, whereas TS and AS decreased. TS was 15.25% lower in the 20% flaxseed‐containing tortilla as compared to the control sample. The AS content was 12.65% lower in the composite tortilla. RS content in the samples ranged between 1.92% for the control sample and 5.08% for the tortilla containing 20% flaxseed. The reduced enzymatic starch hydrolysis rate and pGI recorded for the flaxseed‐added tortilla, indicated slow digestion features. CONCLUSIONS: Flaxseed‐added tortilla might be used to increase the consumption of α‐linolenic acid in the daily diet and modulate starch digestibility of corn tortilla. This kind of product may be used by people with special diet reqirements. Copyright © 2008 Society of Chemical Industry     

Nixtamalisation of maize (Zea mays L) using a single screw cook-extrusion process on lime-treated grits

The tortilla flour market is expanding but present industrial production is lagging behind in the use of modern technologies to increase production and cut costs due to the maize steeping and drying operations. A process using a single-screw cook-extruder which eliminates the traditional steeping and drying operations was therefore explored. Lime (Ca(OH)₂) suspension was absorbed onto commercial maize grits (2 g lime kg^?1 maize) and the resulting meal conditioned to various moisture contents. These samples and one which had not been lime-treated were cook-extruded through a Brabender Do-corder extrusion cooker (Type 825602). The dry extrudate was milled through a 150 μm sieve and tortillas made from each sample. The tortillas prepared from the lime-treated grits conditioned to 472 g kg^?1 moisture compared favourably with that prepared from traditionally prepared masa flour when organoleptically assessed. Flour pasting properties (viscosity) and water absorption index were not significantly different (P < 0.05) from the traditionally prepared products. Enzyme susceptible starch index did not correlate well with dough quality.     

The effects of acid and oxidative modification on the expansion properties of rice flours with varying levels of amylose

This study evaluates the effects of acid and oxidative modifications on the development of the expansive properties of rice flours with varying levels of amylose. Rice grains of the cultivars Embrapa-7 Taim (high amylose), BRS Firmeza (medium amylose) and Motti (low amylose) were used. The rice flours were modified with lactic acid and oxidised with hydrogen peroxide at concentrations of 4 g H₂O₂/100 g flour and 8 g H₂O₂/100 g flour in 5 h, 21 h and 27 h reactions. The rice flours were evaluated for chemical composition, pasting properties, carbonyl and carboxyl contents and expansion properties. The effects of modification with lactic acid and oxidation with hydrogen peroxide were more intense in the flour with the lowest amylose content. The modification of rice flour with lactic acid promoted a reduction in amylose content and in pasting viscosity; the exception to this finding was the peak viscosity of Motti rice flour. The acid and oxidative modifications not changed the specific volume of biscuits made with Taim (1.33 mL/g) and Firmeza (1.88 mL/g) rice flours, however for the Motti rice flour promoted the development of baking expansion. The specific volume increased of 6.53 mL/g in biscuits with native Motti rice flour to 15.80 mL/g in biscuits made with Motti rice flour oxidised with 8 g/100 g of hydrogen peroxide for 27 h.     

Quality parameters and baking performance of commercial gluten flours

Commercial gluten which is labeled in different ways, i.e., gluten, gluten flour, glutinated flour, is sold without any specifications. Breadmaking potential of commercial gluten was assessed by adding them in different concentration levels (6 and 50 g/100 g) to wheat flour. This evaluation was done by physicochemical analyses and subjective characterization. Protein content of commercial glutens ranged from 15.2 g/100 g to 75.2 g/100 g. Diastatic activity of glutinated flours was around 30% lower than the values of wheat flour, while this activity in gluten flours was 24 - 79% lower than wheat flour values. Direct correlation was observed between protein content of blends and loaf volumes: breads volume value increased with the percentage of protein in blends (r_s=1). Furthermore as the percentage of protein in flour blends increased (up to 17.5 g/100 g) scores for smell, crumb color, crumb grain, crumb texture and eatability improved. Breads obtained by incorporating 6 g/100 g of gluten flour or 50 g/100 g of glutinated flour to a wheat flour had the best scores. Breads containing the highest protein content (50 g/100 g gluten flour) were refused by taste panelists, however, after being sliced and toasted they were rated acceptable.     

Effect of damaged starch on acrylamide formation in whole wheat flour based Indian traditional staples, chapattis and pooris

Variation in acrylamide content of two Indian traditional products, chapatti and poori was observed with respect to the damaged starch content in whole wheat flour of different wheat varieties from which these products were prepared. Wheat cultivar ‘lokwan’ was milled by altering mill aperture, feed rate and moisture content to obtain whole wheat flour with damaged starch contents ranging from 6.23% to 28.12%. Acrylamide content of the chapatti and pooris prepared from such flours ranged from 12.5 to 65.5 μg/kg in chapatti, and 25.5 to 130.5 μg/kg in pooris. Impact of several additives showed 10 μmol/g flour citric acid, and 100 μmol/g flour calcium chloride to reduce acrylamide in pooris by approximately 54% and 72%, respectively, without altering the sensory analysis of the products.