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Nixtamalization is the cooking of corn grains, traditionally in water with wood ashes or alkaline compounds. However, due to the pollution caused, the use of other calcium salts or weak acids, as well as alternative processes, has been explored. The pericarp and endosperm comprise 80.5–92.9% of the total weight of the grain and therefore have great effects on handling during processing and the quality of nixtamalized corn-based products. An introduction to nixtamalization processing conditions is followed by reviews of the microstructure and composition of the pericarp and endosperm, and the effects of nixtamalization on the structures and compositions of these tissues. In particular, the processing of raw corn into masa (dough) affects the gelatinization of starch, the interactions of starch with calcium and amylose-lipid complexes, with impacts on pasting properties and digestibility. Finally, the research required to underpin the development of new processing alternatives is discussed.

Little attention has been given to the influence of non-gluten components on the viscoelastic properties of wheat flour dough, bread making process and their products. The aim of this study was to evaluate by creep tests the viscoelastic properties of tablets manufactured from Osborne solubility fractions (globulins, gliadins, glutenins, albumins and residue), pentosans, flour and bread. Hard and soft wheat cultivars were used to prepare the reconstituted tablets. Sintered tablets (except flour and bread) showed similar values to those obtained from the sum of the regression coefficients of the fractions. Gliadins and albumins accounted for about 54% of the total elasticity. Gliadins contributed with almost half of the total viscosity (45.7%), and showed the highest value for the viscosity coefficient of the viscous element. When the effect of dilution was evaluated, the residue showed the highest instantaneous elastic modulus (788.2 MPa). Retardation times of the first element (λ1~ 3.5 s) were about 10 times lower than the second element (λ2~ 39.3 s). The analysis of compliance of data corrected by protein content in flour showed that the residue fraction presented the highest values. An important contribution of non-gluten components (starch, albumins and globulins) on the viscoelastic performance of sintered tablets from Osborne fractions, flour and bread was found.

Biodiversity contributes to nutrient production and, together with processing, is a critical factor in product quality. Physicochemical and nutritional properties of toasted tortillas (totopos) were evaluated in 1) maize samples from Oaxaca communities and 2) maize races of different endosperm texture. Texture profiles show that totopos elaborated from Zapalote Chico maize race showed the best performance (low breaking force) and higher crunchability, similar to commercial totopos. Quality of Zapalote Chico totopos was explained by flotation index (FI) and starch viscosity as well as thermal properties. FI was negatively correlated with texture that may related to end use. Zapalote Chico maize gelatinizes at higher (P 0.05) peak viscosity (3,093–4,723 cP), suggesting a more organized starch structure. In hybrid and Tuxpeno samples, most of the starch granules (90%) were gelatinized and increased the hardness in totopos. The totopo samples in...

Tamales were prepared with 3 nixtamalization processes (traditional, ecological, and classic) and evaluated for chemical composition, starch properties, and glycemic index. Resistant starch (RS) in tamales increased 1.6 to 3.7 times compared to raw maize. This increment was due to the starch retrogradation (RS3) and amylose-lipid complexes (RS5) formation. Tamales elaborated with classic and ecological nixtamalization processes exhibited the highest total, soluble and insoluble dietary fiber content, and the highest RS content and lower in vivo glycemic index compared to tamales elaborated with traditional nixtamalization process. Thermal properties of tamales showed 3 endotherms: amylopectin retrogradation (42.7 to 66.6 °C), melting of amylose lipid complex type I (78.8 to 105.4), and melting of amylose-lipid complex type II (110.7 to 129.7). Raw maize exhibited X-ray diffraction pattern type A, after nixtamalization and cooking of tamales it changed to V-type polymorph structure, due to amylose-lipid complexes formation. Tamales from ecological nixtamalization processes could represent potential health benefits associated with the reduction on blood glucose response after consumption.

The objective of this work was to evaluate the changes in the thermal and structural properties of maize starch during nixtamalization and the tortilla-making process and their relationship with grain hardness. Three maize types with varying hardness (hard, intermediate, soft) were processed by three nixtamalization processes (classic, traditional and ecological). Starch from the three maize types showed an A-type pattern and two endotherms corresponding to gelatinization and melting of the Type I amylose-lipid complexes. After cooking and steeping, in intermediate and soft grains the partial gelatinization and the annealing affected the starch properties and promoted the formation of amylose-lipid complexes. These effects were not observe in hard grains. The increase in melting enthalpy and the intensity of the peak 2θ∼20° from nixtamal to tortillas demonstrated the formation of amylose-lipid complexes. A third endotherm above 114 °C in some treatments of nixtamal and tortilla starch demonstrated the transformation of some amylose-lipid complexes in a most ordered structures (Type II complexes). The V-type polymorph structure found in native starch, nixtamal, and tortilla corresponds to a coexistence of Type I and Type II complexes. Formation of amylose-lipid complexes in tortillas had a partial effect on decreasing starch retrogradation (r = −0.47, P

This research aimed to evaluate the effect of different calcium compounds and their concentration on the viscoelastic parameters of flours and tortillas obtained with traditional and ecological nixtamalization. Specimens (tablets) of nixtamalized flours and tortillas (14% moisture) prepared with three different calcium sources and four concentrations were sintered using a die and a hydraulic press and were evaluated by stress-relaxation tests with a texturometer. Data collected from the stress-relaxation curve were fitted into a three-element generalized Maxwell model (r2 = 0.9999), allowing the detection of significant differences in the estimated viscoelastic parameters. When flours are processed into tortillas, the most notable change was the increase of +88.44% and +73.44%, respectively, in the summation of the elastic modulus, and the compressional viscosity in samples produced with CaCO3. On the contrary, tablets from samples with Ca(OH)2 presented a sharp diminishing (loss) in both of the evaluated viscoelastic parameters, accounting a decrease of -39.82% and -46.28% for the elastic modulus and compressional viscosity summations, respectively. Highly significant correlations were found among viscoelastic parameters when a slight proportional increase was observed in the specific elastic moduli, meaning that the energy was stored by each elastic element in the tablets, while the compressional viscosity coefficients varied as a function of time. Finally, it was found that the residual spring due to the pure elastic component (E0 ) stored energy during the entire test. PRACTICAL APPLICATION: There is no published information about a simple methodology for the evaluation of the viscoelastic properties of dry nixtamalized flours (powder) with a texturometer. The method proposed was sensitive and accurate, since it was capable of detecting differences among samples processed under distinct processing factors conditions. The study of viscoelastic properties of grain foods contributes to the construction of molecular theories occurring in their chemical compounds, which is strongly related to food texture. Those theories are handy to improve nutritional and textural properties of grain foods and are essential to powder handling, processing, and transportation, which allows the processing factors optimization.

Tamales were produced using a traditional nixtamalization process. The nixtamal was milled into masa, mixed with shortening, and boiled to prepare tamales. Enzymatic methods and DSC enthalpies were used to investigate resistant starch (RS) and starch–lipid complexes (resistant starch 5; RS5). The addition of shortening to masa showed an endotherm of lipid melting with To(m), Tp(m), and Tf(m) of approximately 40, 44, and 50°C, respectively. Processing masa by boiling at >90°C for 2 h to make tamales showed three endotherms: one related to amylopectin retrogradation (RS3), one to starch gelatinization (G), and one to Type I complex (RS5). The retrograded amylopectin presented temperatures of 49, 55, and 60°C for To(RS3), Tp(RS3), and Tf(RS3), respectively. The X-ray diffraction pattern showed that during processing starch Type A complexed with lipids to form a Type V (RS5) amylose–lipid starch complex. The RS5 in tamales estimated by DSC affected blood glucose levels from in vivo tests.

There is no previously published data covering the viscoelasticity of Osborne protein solubility fractions. Therefore, the objective of this study was to compare the viscoelastic properties of Osborne fractions, water soluble pentosans, flour and bread using relaxation tests. Sintered tablets from glutenins presented similar elasticity as gliadins but almost twice the viscosity. However, most of the wheat viscoelasticity performance in tablets was given by the sum of the non-gluten components (albumins, globulins, residue and especially water soluble pentosans). The residue was 86.1% w/w in flour and contained 4% protein while its estimated viscoelastic effect was higher compared to all the other flour components. Regarding the estimated viscosity in flour due to protein from specific fractions, it was higher in gliadins compared to glutenins. The residue although has low protein in flour (4.0%), the large amount of residue in flour had significant viscoelastic effect. The viscoelasticity of water soluble pentosans corrected by weight was similar to the Osborne protein fractions. The results indicate that the starch, pentosans, and non-gluten components may not be considered merely as inert filler and play a major role in determining the viscoelastic nature of flour and bread.

The aim of this study, was to evaluate the effect of extrusion conditions and particle size index on the starch properties of expanded nixtamalized snacks elaborated with whole blue corn. Whole grains were ground to achieve two different particle size indexes (PSI), 83.9 and 94.1, and were extruded at three feed moistures (14, 16.5, and 20.5%). The data suggested that the severity of milling and the extrusion process resulted in higher starch degradation, specifically in the snacks obtained with a feed moisture of 20.5%, which showed the higher values of starch damage. Nixtamalization by extrusion produced minimum amounts of resistant starch, mainly as retrograded starch and amylose-lipid complex, as demonstrated by thermal and structural analyses. Snacks produced with feed moisture of 16.5–20.5% and a PSI of 94.1 showed the highest values of resistant starch. The rheological properties of snacks with PSI of 83.9 indicated lower starch degradation and presented lower amounts of resistant starch than snacks with higher PSI. The feed moisture affected all the parameters evaluated in the snacks more than the PSI.

The objective of the present work was to study the effect of annealing and concentration of Ca(OH)2 (lime) and calcium salts on the thermal and rheological properties of maize starch during an ecological nixtamalization process. Thermal and rheological properties of maize starch changed during the ecological nixtamalization process because of three main causes: the annealing phenomenon, type of calcium salt, and calcium salt concentration. In all treatments thermal properties (To, Tp, and Tf) of nixtamal starch increased owing to the annealing process, whereas the type of salt or lime increased thermal properties and decreased pasting properties in this order: CaCl2 > CaSO4 > Ca(OH)2 ≈ CaCO3. This behavior was because of the dissociation of each salt or lime in water. Anions (OH−) can penetrate much more easily into the starch granule and start the gelatinization process by rupturing hydrogen bonds. Additionally, amylose-lipid complexes were formed during the nixtamalization processes, as indicated by an ...

The objective was to evaluate corn tortillas made from three nixtamalisation processes including Traditional with lime (TNP), Classic with ashes (CNP) and Ecological with Ca salts (ENP), and their effect on mineral content (Ca, Fe, K, and Mg), chemical composition, resistant starch (RS), and glycemic index (GI). ENP with calcium propionate and carbonate had higher fat values than tortillas from CNP. EPN and CNP presented the higher dietary fibre, explained by the highest pericarp retention. In TNP the pericarp and external layers were lost during the cooking, steeping and washing steps and had lower crude fiber. The amount of RS increased in nixtamal and tortillas independently of nixtmalisation processes. Annealing of starch was shown by the increase of onset, peak and final gelatinisation temperatures in nixtamalised products compared with untreated maize. Gelatinisation was higher for calcium propionate ENP and 1% ash CNP. Native maize changed from A-type to V-type pattern in nixtamalised products denoting the formation of amylose-lipid complexes. Overall, nixtamalisation processes and salts used increased RS. The GI was affected by chemical composition in tortillas and amount of RS. Tortillas made from ENP Ca propionate and ENP 1% ash CNP can be classified as low GI foods.

The objective of this work was to study the formation of resistant starch (RS) in tortillas from an ecological nixtamalization process compared with the traditional nixtamalization process. The RS increased through all the steps of tortilla production. It was found that the increase of the RS corresponds mainly to the formation of RS5 (V-amylose-lipid complex), but in tortillas two major types of RS coexist: RS5 and RS3 (retrograded starch). In general, tortillas from the ecological nixtamalization process gave higher values of protein, lipids, total dietary fiber, insoluble fiber, soluble fiber, and RS compared with tortillas from the traditional nixtamalization process and commercial flour. The highest glycemic index (GI) occurred in the tortillas from commercial flour, whereas tortillas from 0.4% CaCO3 and 0.6% CaSO4 were classified as medium-GI (GI 50–70). Tortillas from 0.6% CaCl2 had the lowest value of GI. The ecological nixtamalization processes caused significant differences in quality and nutrit...

The viscoelastic characteristics of nixtamalized corn masa were assessed by the dynamic oscillatory test. Masa samples were prepared with flours obtained by nixtamalization with different calcium sources: Ca(OH)2 (traditional), wood ashes (classic), CaCO3 (ecological), CaSO4 (ecological), CaCl2 (ecological), and Ca(C2H5COO)2 (ecological). A sample cooking without calcium source was used as control. Storage (G') and loss (G'') moduli were higher in masa from traditional and classic processes indicating a more elastic and viscous masa. Masa of flours from CaCl2 and Ca(C2H5COO)2 had the lowest values of G' and G''. Viscoelastic properties were explained in terms of the degree of starch gelatinization, the hydrolysis of pericarp and fibre content, the calcium-starch and calcium-zein interactions, as well as the presence of amylose-lipid complexes. Nixtamalization with Ca(OH)2 and wood ashes gave the best viscoelastic characteristics of masa.

The aim of this work was to study the effect of three nixtamalization processes using wood ashes, Ca(OH)2, and CaCl2 on the physicochemical properties of beans. Raw beans had C-type starch, 10.10% resistant starch (RS), and two DSC endotherms: 1) starch gelatinization, and 2) melting of amylose-lipid complexes plus protein denaturation. Nixtamalization increased the Ca and Fe content, decreased the RS content to 4.19-4.43%, and produced starch retrogradation. DSC and FT-IR analysis of the flours evidenced a "stabilizing" effect of cooking with NaCl and CaCl2 on bean proteins. In contrast, cooking with wood ashes and Ca(OH)2 produced denaturation of bean proteins, decreasing the second transition enthalpy and absorption bands of amide I, II and III. Results showed that traditional and classic nixtamalization of beans are alternatives to obtaining mineral fortified flours that could be used as ingredients in the elaboration of foods with a good nutritional profile.

Several maize landraces were evaluated using microstructural and rheological starch properties and related them to pozole quality. Annealed starch produced during traditional nixtamalization and additional boiling step enhances the viscosity, swelling and starch stability to collapse by forming amylose–lipid complexes. Regarding pozole broth, Cacahuacintle maize (pozole end-use) presented significantly higher (P

Summary Corn tortillas are produced using the traditional nixtamalisation process (TP). Nevertheless, one of the greatest problems that the tortilla industry faces is the high level of losses of solids. The aim of this research was to evaluate the nutritional value of a whole-grain tortilla, produced using an ecological process (EP). In the EP corn was cooked at 90 °C with 1.8% (w/w) calcium sulphate. The grains were steeped, washed and grounded to obtain the masa, which was baked to produce tortillas. Also, tortillas were prepared using the TP and following the same steps as those used in the EP, except that 1.0% (w/w) of calcium hydroxide was used. The tortillas from EP retained 14.05, 6.03, and 54.02% more fat, protein and fibre than tortillas produced by the TP. The PER value of rats fed whole-grain tortillas (1.81) was not different from that of rats fed the traditional tortillas (1.85).

Sorghum contaminated with a total concentration of aflatoxin B 1 (AFB 1 ) and aflatoxin B 2 (AFB 2 ) at 140 ± 7.3 ng/g was extrusion-cooked in a single screw extruder. The temperature profile in the barrel sections of the extruder was 80–150–200 °C. The flour moisture content (M.C.) was adjusted at 200, 250 and 300 g/kg by means of aqueous citric acid at concentrations of 0, 0.5, 1, 2, 4 and 8N. The barrel temperature profile, in combination with the M.C. and the citric acid concentration, significantly affected the extent of aflatoxin reduction in the extruded sorghum. The recovered aflatoxin decreased with an increase in M.C. and acid concentration. The maximum percentage of aflatoxins degraded from cooking the milled sorghum ranged from 17 to 92%. Even when using a severe extrusion condition combined with high citric acid concentrations, acceptable product colour, viscosity, functional and textural properties were obtained.

Sorghum fl our contaminated with β-afl atoxins at a level of 140±7.34 ng/g was extrusion-cooked in a single screw extruder under two different conditions: moderate (ME) and severe (SE). The difference in the processing conditions was in the temperature profi le of the barrel sections of the extruder: 60-80-100°C for ME and 80-150-200°C for SE, respectively. The fl our moisture content (MC) was adjusted at 20, 25 and 30% by means of aqueous lactic acid (LA) at concentrations of 0, 0.5, 1.0, 2.0, 4.0 and 8.0 N. The effect of the three extrusion variables (temperature profi le, MC and LA concentration) was analysed as a completely randomized factorial design 2 ×3 × 6. The barrel temperature profi le, in combination with the MC and LA concentration, signifi cantly affected the extent of afl atoxin reduction in the extruded sorghum. The recovered afl atoxin decreased with an increase in MC and LA concentration, in both temperature-profi les evaluated. The SE condition produced higher afl atoxin degradation rates (from 16.38 to 67.09%) than the ME condition (up to 19.79%).