Nixtamalized Corn Flour Research Articles

Effect of ultrasound processing on the physical and powder-flow properties of nixtamalized corn flour and its influence on the quality parameters of tortilla

Effect of ultrasound processing on the physical and powder-flow properties of nixtamalized corn flour and its influence on the quality parameters of tortilla

Exploring Corn Cob Gasification as a Low-Carbon Technology in the Corn Flour Industry in Mexico

In 2021, Mexico produced approximately 24.2 million tons of white corn, generating 3.6 million tons of corn cob residue. The final disposal of corn cob poses an environmental challenge in certain regions. This study examines the technical–economic feasibility and the greenhouse gas (GHG) mitigation potential of integrating a small-scale cogenerating gasifier fueled by corn cob into a nixtamalized corn flour manufacturing small and medium-sized enterprise (SME). This integration enables the generation of heat and electricity from the produced synthesis gas. Moreover, the process yields residual carbon, which can be used as biochar for soil restoration and removing atmospheric CO2. This option holds significance for the corn flour agroindustry in Mexico, as, in 2021, it consumed approximately 601.9 GWh of electrical energy and 938,279 GJ of thermal energy from LP Gas in its manufacturing processes to produce 2.6 million tons of nixtamalized white corn flour. These processes contributed to a total emission of 410,232 tons of CO2 into the atmosphere. The findings of this study demonstrate a cumulative reduction of 51.7% in CO2 emissions, resulting in economic benefits of USD 85,401 in 2017 for a case study SME that annually produces 1039 tons of corn flour. This study reveals the integration of a gasifier–cogenerator system fueled by corn cob as an economically viable low-carbon technology in the corn flour manufacturing industry.

Performance evaluation of maltogenic amylases on nixtamalized corn flour tortilla

AbstractBackground and ObjectivesA high‐performing maltogenic amylase was developed to provide better water‐binding properties to delay staling more effectively than first‐generation maltogenic amylases. This study evaluated the effects of this high‐performing maltogenic amylase and a first‐generation maltogenic amylase (referred to as “maltogenic amylase”) for delaying staling in nixtamalized corn flour tortillas. The maltogenic amylase and high‐performing maltogenic amylase were tested at 25, 50, and 100 ppm and were compared to control tortillas.FindingsTortillas with 100 ppm high‐performing maltogenic amylase were 66% softer and performed better in foldability than control tortillas after 35 days of room temperature storage and rated better in taste and tenderness than the control.ConclusionsBoth maltogenic amylases delayed staling and prolonged softness and foldability.Significance and NoveltyOverall, the high‐performing maltogenic amylase did not outperform the first‐generation maltogenic amylase at 25 and 50 ppm. However, at a higher dosage (100 ppm), the high‐performing maltogenic amylase is capable of producing overall softer tortillas with improved tenderness and taste across 35 days of storage. This research is novel as this high‐performing maltogenic amylase has not been studied by others to improve the quality of tortillas.

Printability of Nixtamalized Corn Dough during Screw-Based Three-Dimensional Food Printing.

This study aimed to analyze the printability of corn-based dough during screw-based three-dimensional (3D) food printing (3DFP) by relating its rheological and mechanical properties to its screw-based 3DFP performance, with the objective of providing insights into the utilization of corn-based dough to produce 3D-printed foods. Screw-based 3DFP was performed using seven corn-based doughs with different nixtamalized corn flour (NCF) and water contents. Afterward, their rheological and mechanical properties were analyzed and associated with their screw-based 3DFP performance. The results showed that stable printability was obtained within a specific range of NCF content in the dough (30-32.5 wt%). Below this range, the 3D-printed foods flattened, while above it, the extrudability of the dough was affected. The printability of the dough was influenced by different rheological and mechanical properties, depending on the stage of the screw-based 3DFP process. During the extrusion stage, the loss tangent at nozzle strain, yield stress, apparent viscosity, and adhesiveness mainly affected the extrudability of the dough. In contrast, the loss tangent at minimum strain, elastic modulus, Young's modulus, and hardness influenced the self-supporting stage. Therefore, it is important to find a balance between all of these properties, where stable extrudability and self-supporting of the 3D structure are achieved.

Evaluation of xanthan gum and ascorbic acid in the physicochemical properties of bean/corn flour and pound cake

This work aimed to evaluate the effect of xanthan gum and ascorbic acid on the techno-functional properties of bean/corn composite flour for producing and evaluating a pound cake. The composite flours were formulated with bean flour (80%) and nixtamalized corn flour (20%) using xanthan gum and/or ascorbic acid in different concentrations (0, 0.25 and 0.50%). The different flours composed of beans/corn were evaluated for their water absorption capacity (2.68 to 3.84 g/g), oil absorption capacity (1.14 to 1.43 g/mL) and swelling capacity (10.57 to 10.98 mL/g). The different flours composed of beans/corn were used for the production of pound cakes. As the content of xanthan gum and/or ascorbic acid increased, the different pound cakes presented better weight, volume and volume index. Likewise, the nutritional quality of the pound cake is improved, compared to the flour used individually.

Effect of calcium hydroxide on pasting, thermal, and water‐adsorption behavior, and the flow properties of nixtamalized corn flour

AbstractNixtamalized corn flour (NCF) has gained favor worldwide due to the growing popularity of Mexican cuisine. This research evaluates the effect of the amount of calcium hydroxide (Ca(OH)2) employed during the nixtamalization on the water‐adsorption, thermodynamic, and flow properties of NCF. In addition, NCF pasting and thermal properties were evaluated to relate bulk‐powder properties to wet‐dispersion conditions. Ca(OH)2 amounts of 1.5 and 2.0% induced higher ash and calcium content as well as lower fat and protein content. Also, pasting properties and gelatinization enthalpy (ΔHgel) values, in addition to yellowish NCF, were related to Ca(OH)2 concentration. With the independence of the Ca(OH)2 amounts employed, no important differences in the equilibrium's moisture content, as well as a negligible effect of temperature on adsorption behavior, were observed. For prepared NCF, the moisture content corresponding to minimum integral entropy was not observed within the range of the aw analyzed; thus, GAB parameters are more reliable for suggesting the storage conditions. NCF with a low amount of Ca(OH)2 exhibited higher values of mean caking strength (≈1.81 N) and cohesiveness index (≈13.99 × 10−5 N m g−1), in addition to higher resistance to flow. Therefore, the amount of Ca(OH)2 positively influenced flow properties, whereas wet‐dispersion properties such as lower maximal peak viscosity and ΔHgel values were obtained.Practical applicationsThis study contributes useful information to the manufacturers of NCF concerning the amount of Ca(OH)2 needed to obtain NCF with desirable physical properties while attempting to affect thermal and pasting properties to a lesser extent. In addition, this study characterizes and provides the adequate amount of Ca(OH)2 employed the during the nixtamalization process to improve the flowability of NCF in industry during handling. Finally, the absence of a moisture content corresponding to minimum integral‐adsorption entropy provides clarification for NCF producers regarding the long‐term storage stability of NCF.

Black Bean Hulls as a Byproduct of an Extraction Process to Enhance Nutraceutical and Glycemic-Related Properties of Nixtamalized Maize Tostadas.

Black bean hulls (BBH) are rich in phenolic compounds, such as anthocyanins, which can be incorporated into common staple foods such as maize tostadas, enhancing the nutraceutical properties of these products. This study incorporates black bean hulls to produce nixtamalized maize tostadas with nutraceutical properties. Nixtamalized corn flour (NCF) and black bean hulls (BBH) were characterized in terms of protein, fat, crude and dietary fiber, anthocyanin concentration, and different starch fractions. NCF and BBH depicted 53.7 and 16.8% of total digestible starch (TDS), respectively, and 1.2 and 7.6% of resistant starch (RS), in the same order. BBH was incorporated into nixtamalized flour at 10, 15, and 20% w/w, and the resulting dough was thermo-mechanically characterized. Tostadas with BBH had higher protein, dietary fiber, and anthocyanin concentrations. Enriched tostadas did not show significant changes in texture or other sensory characteristics. However, a reduction in total digestible starch (61.97 up to 59.07%), an increase in resistant starch (0.46 to 2.3% from control tostadas to 20% BBH tostadas), and a reduction in the predicted glycemic index (52 to 49), among other parameters, indicated that BBH is a suitable alternative for developing nutraceutical food products.

Effect of the Incorporation of Virgin Coconut Oil Byproduct in the Optimization Process of a Baked Snack

Snack consumption contributes to the prevalence of noncommunicable diseases because snacks contain high quantities of fat, sodium, and sugar. It is possible to reformulate these foods to improve their nutritional composition by incorporating coconut byproducts. This study aims to improve the nutritional profile of a snack by adding coconut flour to it. A Box–Behnken design was used to study the effects of coconut flour (40-60%), baking time (15-20 min), and temperature (140-160°C) on the physicochemical properties of the snack. There were considered response variables color aspects (L ∗ , a ∗ , b ∗ , C ∗ , and h ∗ ), aw, moisture, BI, and hardness. The R 2 was over 0.73 for aw, moisture, a ∗ , and b ∗ ; meanwhile, as for the rest of the variables, it was lower to 0.71, except for the hardness, for which the model was not significant. For that, the variables considered for the optimization were aw, moisture, a ∗ , and b ∗ . It was found that the moisture content and a ∗ and b ∗ values decreased as the amount of coconut flour increased. Time and temperature reduced the moisture content and the aw and b ∗ values. The optimum conditions of coconut flour amount, time, and temperature were 55.3%, 20 min, and 159°C, respectively. The result was a snack with appropriate physicochemical properties and an increase in the content of protein, fat, and ash compared to the nixtamalized corn flour; also, the principal fatty acid of the snack was the lauric acid, characteristic of the coconut. This study validates the production of a snack made with a virgin coconut oil byproduct.

Explorative Study of Reactive Extrusion over Nixtamalization‐Maize Pericarp Residue: Effect on Dietary Fiber, Resistant Starch, and Nixtamalized Corn Flour Tortillas

AbstractInterest in clean label products and decrease of effluents have increased. Nixtamalized maize flour (NMF) residues could be used as by‐products that modify NMF properties without the need for other additives. In this work, pericarp residue of NMF is subjected to reactive extrusion (REX) using 1% or 5% addition of phosphoric acid, sodium metabisulphite, benzoyl peroxide, or titaniumdioxide. The use of pericarp as an ingredient for cereal products has detrimental effects. Dietary fiber content, resistant starch, and moisture are studied to characterize the REX treatment products. Maize compound flours with 5% REX extruded maize pericarp are prepared. The apparent viscosity parameters of composite flours and the physical characteristics of maize tortillas with the compound flours are analyzed.Pasting properties of compound flours is modified with chemical treatment. All REX tortilla treatments show a reduction in thickness without effect on resistance and extensibility, which can positively affect the yield of the product without impact on quality. Compared with control and other treatments, the addition of tortilla produced with phosphoric acid extruded material has the highest resistance to extension after 24 h of production.

Impact of the addition of cricket flour (Sphenarium purpurascens) on the physicochemical properties, optimization and extrusion conditions of extruded nixtamalized corn flour

The aim of this work was to evaluate the effect of the concentration of cricket flour (0-40%; Sphenarium purpurascens) in the mixture with nixtamalized corn flour on the physicochemical properties and the conditions of extrusion cooking of snacks extruded. The results obtained showed that the linear and quadratic term of die temperature (120-180 °C) was significant causing the reduction of the expansion ratio; the linear terms of die temperature and concentration of cricket flour decreased the resistance to compression of the extrudates; concentration of cricket flour increases the protein content in mixtures; the linear and quadratic term of die temperature causes a decrease in total energy; likewise, by increasing the concentration of cricket flour in the mixtures, the color index increases but causes a decrease in the whiteness index, on the other hand, if the die temperature increases, the acceptability of the extrudates increases. In summary, cricket flour can be used to develop extruded snacks with acceptable characteristics and high protein content.

Production of tortillas from nixtamalized corn flour enriched with Andean crops flours: Faba-bean (Vicia faba) and white-bean (Phaseolus vulgaris)

This study aims to produce corn nixtamalized tortillas enriched with faba-bean (25%, 50%, 75% w/w) and white-bean (25%, 50%, 75% w/w) flours. Faba-bean and white-bean are Andean crops (AC) rich in protein, carbohydrates, fiber, minerals, vitamins, and gluten-free. Tortillas were characterized in terms of proximal, physicochemical, sensorial, microbiological, and texture properties. Proximal composition shows that corn flour has 14.5 % less protein, 0.83 % less ash, and 1.39 % fatter than faba-bean flour, while in white-bean flour, the fiber content is three times higher. Moisture content was less than 14 %, which guarantees the control shelf-life; gluten content was approximately 5 ppm. Granulometry properties showed that flours have coarser than finesse particles, water absorption capacity showed a range of 60 to 80 g of water for 100 g of flour. In nixtamalized tortillas, high protein content was observed in samples with 25 % of corn and 75 % of two different Andean crops. Enriched tortillas showed lower lipid content, higher dietary fiber, and higher ash content than the control sample. The sensorial analysis showed that the best formulation based on overall acceptability was 25% (w/w) of corn flour and 75% of white-bean flour. The oil content showed that the samples absorbed about 8% of oil during the toasted. The hardness parameter showed that the sample CPB2575: Corn flour (25%) + White-bean flour (75%); was harder than the control. The microbiological evaluation established that the tortillas comply with the normative what indicates the absence of harmful microorganisms to public health. Color parameters showed that samples tend to lightness with a tendency to reddish color in enriched tortillas while in control are greenish. Andean crop flours are one alternative to increase the nutritional value of corn tortillas with acceptable sensorial characteristics.

Quality characteristics of snacks produced from nixtamalized corn flours of new drought-tolerant yellow corn hybrids

Introduction. Producing new maize cultivars in areas with limited water resources is the main task of plant breeders. However, there is little information regarding their technological characteristics and industrial potential. Besides, snacks have gained worldwide acceptability and become part of modern food culture, especially among young people and children. Thus, our study aimed to produce corn snacks from new yellow corn hybrids planted under water stress in Delta region, Egypt.
 Study objects and methods. We investigated healthy processing techniques and used nixtamalization and baking instead of frying. We also evaluated the chemical composition and starch crystallinity of flour, the rheological properties of dough, as well as color attributes and sensory characteristics of baked snacks.
 Results and discussion. Significant differences (P ˂ 0.05) were found between all corn genotypes in their fat, protein, ash, crude fiber, and carbohydrate contents. The experimental drought conditions caused higher protein and fat contents compared to normal conditions. X-ray diffraction indicated that nixtamalization decreased starch crystallinity. Also, X-ray and rapid visco analysis showed that Y2 genotype exhibited the highest crystallinity and the lowest pasting properties, while Y3 and Y5 had the lowest crystallinity and the highest pasting properties. Baked snacks made from nixtamalized corn flour of genotypes planted under drought conditions had comparable quality characteristics in terms of color and sensory properties to the control snacks made from SC178 genotype
 planted under normal conditions.
 Conclusion. The new corn hybrids grown in limited water conditions and the developed snacks represent a healthy alternative to cornbased fried snacks.

Development and quality evaluation of gluten-free pasta with grape peels and whey powders

Whey and grape peels powders are valuable by-products which can improve dough technological properties, producing high-quality gluten-free foods. Nixtamalized corn flour present high niacin and calcium availability and represent a good matrix for gluten-free pasta. In this study, the effects of grape peels and whey powders, as dietary fiber source and gluten substitute respectively, on pasta from nixtamalized corn flour were investigated. Gluten-free pasta cooking quality was evaluated, color was measured with a colorimeter, dough and pasta texture was determined by means of a texturometer, microstructure and roughness by confocal microscopy. The sensory profile was investigated by Check All the Attributes method. The results showed that whey powder incorporation determined lower cooking loss, lower dough and pasta firmness, smoother pasta surface and acceptable sensory characteristics. Higher amounts of grape peels powder led to high cooking loss, firmer pasta, heterogenic surface with cracks and holes, lower luminosity and undesired sensory characteristics. Thus, amounts of whey powder up to 15% and grape peels up to 3% are recommended in pasta formulation in order to obtain products with acceptable physical, textural and sensory properties. Our results highlighted the possibility to obtain novel gluten-free pasta with superior functionality and reasonable cost.

Efecto del tamaño de partícula y del contenido de amilosa en la textura de tamales elaborados con mezclas de maíz (<em>Zea mayz</em>), triticale (<em>X. Triticosecale Wittmack</em>) y arroz (<em>Oryza sativa</em>)

Objetivo: en el presente trabajo se evaluó la sustitución parcial de harina de maíz nixtamalizado por harina de triticale y de arroz y su efecto sobre la textura de los tamales utilizando diez mezclas. Metodología: se evaluó la dureza, adhesividad, cohesividad y gomosidad de los tamales, así como el tamaño de partícula y contenido de amilosa de las harinas utilizadas para elaborarlos. Resultados: se observó que los tamales con mayor contenido de arroz tendían a ser más duros seguidos por los de maíz y triticale. A medida que en las mezclas se incrementaba el arroz la dureza del tamal era mayor, mientras que con el aumento de triticale la adhesividad aumentaba, el maíz produce tamales con dureza y adhesividad intermedios. En cuanto al tamaño de partícula de las harinas, la que presentó mayor tamaño fue la de triticale seguida por maíz y arroz; la harina de arroz contiene la mayor cantidad de amilosa, seguida por la de maíz y finalmente triticale. Limitaciones: si bien el estudio muestra la posibilidad de elaborar tamales con otros granos y la influencia de estas mezclas sobre la textura del tamal, es necesario ahondar en el conocimiento sobre la relación existente entre los ingredientes que conforman la matriz particularmente la función de la fracción proteica. Conclusiones: la dureza de los tamales se debe a la contribución de los componentes unitarios derivado de las propiedades de cada harina. Las harinas con gránulos más pequeños y homogéneos producen tamales más duros, pero menos adhesivos. La relación amilosa-dureza indica la fuerte influencia de este componente sobre la textura del tamal.

Gluten-free biscuits produced from new drought tolerant corn hybrids: processing and evaluation

BackgroundDrought tolerance and grain quality are the main challenges in maize cultivation due to climatic changes and population growth. So, this study aims to evaluate the suitability of nixtamalized corn flour (NCF) obtained from new drought-tolerant white corn hybrids planted under drought conditions for gluten-free biscuits production. Chemical compositions of corn hybrids, pasting properties of dough, and physical and sensory characteristics of biscuits were evaluated.ResultsProtein, fat, crude fiber, and ash contents of corn hybrids differed significantly, while there were no significant differences between carbohydrate contents. NCF showed lower peak viscosity, trough value, breakdown, and final and setback viscosities as compared to raw Single Cross Giza (SC 10) flour. This indicates that nixtamalization process reduced retrogradation capability of the produced corn flours. Corn flour with the lowest retrogradation tendency was the one produced from genotype No. 5. Baking quality, sensory properties, and color attributes indicated that biscuits made from NCF of hybrids No. 2 and 5 were significantly more acceptable compared to other samples.ConclusionGluten-free biscuits could be produced using NCF of all white hybrids with acceptable quality. Moreover, superior sensory characteristics of samples manufactured from genotypes No. 2 and 5 and thereby suitable for gluten-hypersensitive patients.

Effect of processing on the hydroxycinnamic acids, flavones, and cellular antioxidant activity of tortillas supplemented with sorghum bran

AbstractBackground and objectivesThe aim of this study was to evaluate the effects of sorghum bran (SB) addition on the bound and free hydroxycinnamic acids, flavone levels, total phenolic compounds, total anthocyanin content, in vitro antioxidant activity, as well as cellular antioxidant activity of corn tortillas prepared with nixtamalized corn flour (NCF + SB).FindingsThe addition of SB increased the bound and free ferulic (FA), p‐coumaric (p‐CA), dehydro‐diferulic (di‐FA), and dehydro‐triferulic (tri‐FA) acids in tortillas. Corn tortillas enriched with 10% of sorghum bran contained higher total ferulic acid (186.78 mg FA/100 g), luteolin (3.05 µg/g), apigenin (2.26 µg/g), cellular antioxidant activity (36.95%), in vitro antioxidant activity (8.79%), total phenolic compounds (172.47 mg GAE/100 g), and total anthocyanin content (12.42 mg/100 g) compared to the control tortilla. The baking process increased the free ferulic acid from 66.6% to 131.2% in tortillas.Despite the effects of lime‐cooking and baking, tortillas prepared with the NCF + SB‐10% retained approximately 86%, 90%, 54%, and 60% of total ferulic acid, total phenolic compounds, antioxidant activity, and total anthocyanin content, respectively. Likewise, the retention of apigenin and luteolin was 62% and 69%, respectively, whereas the retention of the cellular antioxidant activity was 58%.ConclusionsThe tortilla NCF + SB‐10% showed the best phytochemical profile and exerted the highest cellular antioxidant activity. Sorghum bran can be used as a functional ingredient for the production of corn tortillas with higher amounts of ferulic acid, cellular antioxidant activity, flavones, and total phenolic compounds.Significance and noveltyThe supplementation of SB to corn tortillas enhanced the bound and free hydroxycinnamic acids, flavones, total anthocyanins, and cellular antioxidant activity.

Physicochemical study of nixtamalized corn masa and tortillas fortified with “chapulin” (grasshopper, Sphenarium purpurascens) flour

ABSTRACT The objective of this work was to study the physicochemical properties of nixtamalized corn flour (NCF) enriched with grasshopper Sphenarium purpuracens, “chapulin” flour (ChF) at 2, 6, and 10% w/w. Bromatological, vibrational, mineral, structural, thermal, viscosity, textural, and acceptability analyses were done. It was found that the ChF is rich in alkali-soluble proteins and the inductively coupled plasma mass spectrometry (ICP) analysis showed the presence of important minerals to human health like K (4285 mg/kg), P (4137 mg/kg), and S (3281 mg/kg). Viscosity profiles of the mixes of ChF-NCF showed a decrease of viscosity, depending on the concentration of ChF. The hardness in the corn masa added with ChF was less compared with the one made with NCF. Tortilla texture was affected by the addition of ChF. However, the acceptability study revealed that that consumers accept tortillas enriched with 2 and 6% of ChF.

Handmade Comal Tortillas in Michoacán: Traditional Practices along the Rural-Urban Gradient.

Certain components of global food security continue to be threatened. Globalization has impacted food patterns, leading to greater homogenization of diets and the standardization of processes of food transformation, both in the countryside and in the cities. In Mexico, this has led to a drop in the use of native corn landraces and in the value associated with traditional practices around their growing and the processing and consumption of tortillas. The aim of this work was to analyze the main characteristics of the handmade comal tortilla system along the rural-urban gradient taking into account: (1) The type of seed and production, (2) manufacturing processes, (3) marketing channels and purpose of sales, and (4) perceptions regarding the quality of the product. Research was conducted on 41 handmade tortilla workshops located in rural areas in the Lake Pátzcuaro Basin and in urban and peri-urban areas of a medium-sized city in Michoacán (Mexico). Results showed that the origin of the grain follows a gradient-like pattern: In rural areas, tortillas are made with local and native corn predominate, while in urban contexts most tortillas come from hybrid corn produced in Sinaloa or Jalisco. There is a generalized preference for white tortillas, but blue tortillas are used for personal consumption in rural areas and as a gourmet product in the city. 100% of the rural workshops make their own nixtamal, while almost 50% of the peri-urban and urban businesses buy pre-made nixtamal dough. Surprisingly, 50% of the rural handmade tortilla workshops admit that they add nixtamalized corn flour and/or wheat flour to their tortilla mix. We conclude that not all handmade comal tortillas are produced equally and, although in rural areas traditions are better preserved, these also have contradictions. We also conclude that it is important to promote the revaluation of agrobiodiversity, traditional gastronomy, and food security without sacrificing quality, nutrition, and flavor.

Development of a Paper-Based Sensor Compatible with a Mobile Phone for the Detection of Common Iron Formulas Used in Fortified Foods within Resource-Limited Settings.

A lack of quality control tools limits the enforcement of fortification policies. In alignment with the World Health Organization’s ASSURED criteria (affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free, and deliverable), a paper-based assay that interfaces with a smartphone application for the quantification of iron fortificants is presented. The assay is based on the Ferrozine colorimetric method. The reaction started after deposition of the 5 µL aqueous sample and drying. After developing color, pixel intensity values were obtained using a smartphone camera and image processing software or a mobile application, Nu3px. From these values, the actual iron concentration from ferrous sulfate and ferrous fumarate was calculated. The limits of detection, quantification, linearity, range, and errors (systematic and random) were ascertained. The paper-based values from real samples (wheat flour, nixtamalized corn flour, and infant formula) were compared against atomic emission spectroscopy. The comparison of several concentrations of atomic iron between the spectrophotometric and paper-based assays showed a strong positive linear correlation (y = 47.01x + 126.18; R2 = 0.9932). The dynamic range (5.0–100 µg/mL) and limit of detection (3.691 µg/mL) of the paper-based assay are relevant for fortified food matrices. Random and systematic errors were 15.9% and + 8.65 µg/g food, respectively. The concept can be applied to limited-resource settings to measure iron in fortified foods.

Large amplitude oscillatory shear (LAOS) rheology of nixtamalized corn masa

Masa was prepared by mixing 63.0 g of commercial nixtamalized corn flour and 37.0 g of water, and subjected to large amplitude oscillatory shear (LAOS) for assessing nonlinear viscoelasticity. Fourier decomposition of the stress time response was conducted to extract information on nonlinearities. The results showed that nonlinearities were expressed for large deformations higher than 1%. In contrast, the mechanical response was essentially harmonic for small amplitude values, indicating the absence of nonlinearities and hence the dominance of linear viscoelastic response. In particular, nonlinearities quantified in terms of the harmonic contributions were stronger for the elastic response (about 75–100%) than for the viscous response (less than 70%). The results illustrated the viability of LAOS method for characterizing the nonlinear mechanical response of masa made with nixtamalized corn flour.