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Exposure of school children to aflatoxin and fumonisin is mainly through diet. In Kenyan public schools, children are given porridge made from maize flour for breakfast, a mixture of maize and beans, also known as githeri for lunch and ugali for dinner. Nixtamalization has proved to reduce mycotoxins in most cereals and not a mixture of maize and beans. This study, therefore, aimed to assess the exposure of primary school children in Turkana County to aflatoxin and fumonisin through maize-based food under the school meals program and the effectiveness of nixtamalization in the reduction of these mycotoxins. Samples of githeri were randomly collected from all public primary schools (n = 128) under the homegrown school meals program in Turkana County and analyzed for aflatoxin and fumonisin. The data was analyzed using SAS software, version 9.4. The deterministic model was used to calculate the estimated daily intake (EDI) and the margin of exposure (MOE) used to characterize the exposure risk. The contaminated samples were then treated with various concentrations of Ca(OH)2, 0.5–2.5%. The treated samples were cooked for 60 and 75 min and soaked for 6 and 8 h. Forty percent of the schools contained githeri samples with aflatoxin B1 levels above 5 µg/Kg, the maximum limit for Kenya. Exposure to aflatoxin B1 and total aflatoxin was up to 2 µg/kg/bw/day. The range for fumonisin exposure was 60–80 µg/kg/bw/day. Ca(OH)2 concentration levels of up to 2.5% reduced aflatoxin by 75% and fumonisin by 72%. The findings indicate that githeri is contaminated with aflatoxin and fumonisin which exposes school children to these mycotoxins and nixtamalization can be used to reduce mycotoxin contamination in githeri. [ABSTRACT FROM AUTHOR]

Corn is one of the major cereal crops produced worldwide. It has recently been used for the production of healthy, gluten-free, and high-fiber bread. However, corn is highly susceptible to aflatoxin (AF) contamination, representing a serious health concern, as aflatoxins (AFs) are carcinogenic to humans. In this study, the cornbread-making process using the unit operations nixtamalization with different calcium sources, fermentation, and baking was evaluated as a method for AF detoxification at 2 different contamination levels. The nixtamalized cornbread-making process with tequesquite (an alkaline mineral complex) showed an average reduction of 77.12% in AF content from 550.33 µg/kg to 114.50 µg/kg. For the second contamination level (2208.33 µg/kg), the cornbread-making process with the nixtamalization using calcium hydroxide was the most effective, resulting in an average reduction in AF content of 83.58% (362.50 µg/kg). At both levels, the control cornbread samples were significantly different (p < 0.05) from others, reaching an average reduction of 55.43% for level 1 and 58.23% for level 2 (125.73 and 522.33 µg/kg respectively). Additionally, when the AF extracts of cornbread samples were subjected to acidic pH values (pH = 3), an additional reduction in AF content was achieved. The chemical structure of AFs did transform to irreversible forms, with only non-fluorescent derivatives remaining. Our results demonstrate that despite the high contamination of corn used as a raw material, the cornbread-making process including nixtamalization as a unit operation was effective in reducing AF content by more than 80%. [ABSTRACT FROM AUTHOR]

People are focusing more on gluten free food products with minimal production costs. Maize is one of the major cereal crops and provides up to 30 per cent of food calories to 4.5 billion people in the world. Maize was the first plant cultivated by farmers 7000–10,000 years ago in Mexico and later spread to various parts of the world. Maize is generally classified according to its colour, which ranges from white to yellow to red to black. Another major categorization is based on the size and composition of the endosperm containing an appreciable amount of carbohydrates (66.2%), lipids (3.6%), proteins (11.1%) and vitamins and minerals (3.6%) along with fibres (2.7%). Unfortunately, maize is deficient in two major amino acids, namely tryptophan and lysine and also minerals like iron and zinc and vitamin B12. Due to a good nutritional profile, a high proportion of maize grains is processed industrially for transforming into value-added products by three basic methods:- wet milling, dry milling and nixtamalization that enhance shelf stability of the product by preventing the hydrolysis of lipids. This review hopes to facilitate the feasibility of maize incorporation in various food products prepared from other cereal crops and its impact on quality and shelf life with a prime objective to spread awareness regarding nutritional qualities as an alternative to wheat or rice. [ABSTRACT FROM AUTHOR]

Corn kernels were soaked with different selenium (Se) solutions (0, 12 or 24 mg Na2SeO3/L), sprouted for different times and then lime-cooked for the pilot plant production of tortillas. The dough and tortillas were quantified in terms of total Se, starch and protein content. Also, in vitro digestibility, texture, color, and sensory properties were evaluated. Results indicated that lime-cooking times were significantly reduced from 39.15 to 14.34, 8.42 and 2.80 min when whole corn was compared with kernels germinated for 1, 2 or 3 days. The Se content of regular tortillas (0.08 µg/g dw) increased about eight-fold in tortillas (0.651–0.625 µg/g dw) produced of corn germinated for two day and treated with 24 mg of Na2SeO3/L. The highest α-amylase activity and lower starch viscosity values were observed in 3-day germinated supplemented with the highest Se. Se-enriched tortillas produced from 2-day sprouted kernels treated with 12 mg Na2SeO3 showed the highest levels of general acceptability, texture and flavor. [ABSTRACT FROM AUTHOR]

Grain sorghum is a viable feedstock for lactic acid fermentation; however, tannins contained in some varieties affect the efficiency of hydrolysis and fermentation. This work objective was to assess the effect of pre-treatment of grain sorghum on the production of lactic acid and biomass after fermentation. Sorghum varieties with low, medium, and high tannins were pretreated, enzymatically hydrolyzed, and fermented with Lactobacillus casei. The pre-treatments consisted of cooking the grains in lime, cooking in plain water, and no treatment (control). Pretreated sorghum flours were hydrolyzed using thermostable α-amylase from Bacillus licheniformis and amyloglucosidase from Aspergillus niger. Lime pre-treatment showed a significant improvement in protein content, digestibility, and lactic acid production after fermentation, in relation to the non-treated samples. Although differences were not significant for low and medium tannins, lime treatment increase lactic acid production for the cooked-in-lime high-tannin sorghum in relation to the control. For this sorghum/treatment combination, the lactic acid production was 138 g/L, with a volumetric productivity of 1.57 g/L·h and 85/100 g yield based on initial starch, which is equivalent to 69 g of lactic acid per 100 g of sorghum d.b. [ABSTRACT FROM AUTHOR]

The identification and quantification of phenolic components separated by ultrafiltration from the alkaline cooking water of three varieties of Mexican maize (white, red and purple) were performed. The total content of polyphenols and the antioxidant activity of the permeate was evaluated. The cooking water (Nejayote) obtained from the nixtamalization process was subjected to a consecutive fractionation process with three membranes of different molecular cutting (MF-UF100-UF1) for the recovery of bioactive components. The highest content of total polyphenols recovered in the fractions was with the integrated MF-UF100 process (UF100-Permeate of white maize, red maize and purple maize) with values of 768.22, 800.72 and 776.88 mg GAE L−1, respectively; and the antioxidant activity in the same fractions was 0.43, 0.33 and 0.33 TE mL−1, respectively. The UHPLC-ESI-MS showed that the hydroxycinnamic acids present at the end of the initial process proposed (MF-UF100-UF1) were ferulic acid and p-coumaric acid; those that were present in the fractions of UF1-Permeate (of white corn, red corn and purple corn) in quantities of 99.89, 138.85 and 211.03 mg L−1, of ferulic acid respectively and p-coumaric acid in amounts of 24.56, 31.88 and 76.21 mg L−1, respectively. The results allow us to visualize possible applications in food industry (bakery products and pastry, mainly) for extracts from Nejayote. [ABSTRACT FROM AUTHOR]

Acrylamide can be generated from food components during tortilla chips frying. Thus, the aim of this research was to study different nixtamalization processes as traditional (TNP) with lime [Ca(OH)2], ecological (ENP) with CaCO3, classic nixtamalization (CNP) that uses wood ash and extrusion (EXT) with no Ca+2 source on mitigating the acrylamide formation in deep-fat frying tortilla chips. Acrylamide quantification was done through HPLC–UV. Lower acrylamide content in tortilla chips was for CNP with 46.3 µg/kg, followed by TNP with 55.0 µg/kg, ENP with 694.6 µg/kg and EXP with 1443.4 µg/kg. Differences in acrylamide values among samples can be related to effect of cations (Ca2+, Mg2+, Fe2+, Zn2+, Na+ and K+) present in wood ashes, lime and salts used as raw materials. Correlation of (r = 0.85; p <0.0005) was observed in color of tortilla chips, moisture, texture, blisters, and oil with acrylamide. Nixtamalization process is an effective and inexpensive strategy for acrylamide mitigation. [ABSTRACT FROM AUTHOR]

This study aimed at evaluating the effect of high-energy milling (HEM) and traditional nixtamalization (TN) on bioactive compounds and antioxidant capacity in nixtamalized creole corn flours obtained from a maize genotype cultivated under rainy temporal conditions in the Mexican semidesert. Four creole grains, including San José de Gracia white and blue (WG and BG), Negritas (NG), and Ahualulco white corn grains (SG), were used. For HEM nixtamalization, corn grains were hammer-milled; then, two different conditions were evaluated: treatment H1, with raw flours with 14% moisture content and 1.1% Ca(OH)2, and treatment H2, with raw corn flours with a 23% moisture content and 1.4% Ca(OH)2. The TN process was utilized as a control. TN recorded significant losses in luminosity value L* (p < 0.05), while HEM nixtamalized blue corn flours remained close to -b* values, that is, near to those of raw flour. Anthocyanin content showed higher content values in HEM treatments compared with TN (759.55 and 252.53 mg cyanidin 3-O-β-D-glucoside (C3G)/kg, respectively) (p < 0.05). Total soluble phenolic content was higher in HEM nixtamalization compared with the traditional process, except for WH2 and SH2 (H2 treatment for WG and SG). Two redundant radical scavenging assays were used: antioxidant capacity (DPPH assay) exhibited less value in nixtamalized flours than in raw flour (p < 0.05). Antioxidant activity by (ABTS) assay was higher in HEM than in TN. Nixtamalized flours produced by HEM demonstrated more improvement in nutraceutical properties than those produced employing TN. [ABSTRACT FROM AUTHOR]

The production of nixtamalized products worldwide has been increased over past decades. The first pre-treatment applied to maize is the well-known Nixtamalization procedure, which produces large quantities of its primary by-product called 'Nejayote'; this by-product is commonly discarded into the urbanized sewage without any additional treatment. Recently, Nejayote has attracted attention due to its high organic load based on high content of organic (arabinoxylans, phenolic compounds, sugars, fibers) and inorganic compounds (calcium). Thus, this by-product may have potential for value-added processing and utilization, which can be alternatives, that simultaneous hold the promise of increased economic benefit for masa producers as well as decreased potential pollution for the environment. The goal of this paper is to provide a critical review of reusing this primary by-product. State-of-the-art of developments in the field are chronologically reported and described. Particular attention is paid to experimental results reported for the reclamation of its high-added value compounds that have been identified as the potential approach concerning on the utilization of the by-product. The recovered components have demonstrated biological activities that increase their potential exploitation. [ABSTRACT FROM AUTHOR]

Nixtamalized maize tortilla is a basic food for the Mexican population. It has high energy due to high starch, which may be modified to decrease its bioavailability and to produce changes in the characteristics of flours. For this research, nixtamalized maize flour was prepared and subjected to an acetylation chemical process, with and without prior hydrolysis. Raw maize flour, traditionally nixtamalized maize flour, acetylated-nixtamalized maize flour (AF) and acetylated-hydrolyzed nixtamalized maize flour (AHF) were prepared and evaluated. These flours were used for dough and tortilla preparation and analyzed for degree of substitution (DS), physicochemical properties, structure, thermal, rheological, morphological and texture properties. FTIR spectra and DS showed the presence of acetyl groups. AHF showed the highest value for water absorption index. The resistant starch increased 0.27 and 0.42% for AF and AHF samples. The gelatinization enthalpy (∆Hg) for AF was greater than other flours. AF tortillas showed better characteristics than the traditional ones and their consumption was recommended since showed better RS. [ABSTRACT FROM AUTHOR]

Blue purple maize grain loses a great amount of anthocyanins during the nixtamalization processing. The impact of the process factors on anthocyanins losses has not been studied in detail. The objectives of this work were to: (1) determine the step of the nixtamalization procedure where the greatest anthocyanin loss occurs and (2) study the effect of cooking time, alkali concentration, and sample size on anthocyanin losses (AL), and on the color of masa and tortilla from blue purple maize grain. Two cooking times were assayed (25 and 35 min), three alkali concentrations (0.5, 0.7, and 1.0% w/w), and two maize grain sample sizes (100 and 1000 g). Alkali concentration determines the time required to solubilize the maize grain pericarp, higher concentrations resulted in shorter maize grain pericarp solubilization times and this variable was related with AL. The greatest AL occurred during the grain cooking step, but an additional loss took place during the steeping of cooked grain. For the cooking time of 25 min, AL were of 38.3% during the cooking step, and 21.3% during the steeping of cooked grain. The cooking time had no effect ( p > 0.05) on AL in masa and tortilla whereas alkali concentration and sample size significantly affected it. The greater the concentration and size, the higher the AL. The color of masa and tortilla were affected by cooking time and alkali concentration. Increasing alkali concentration during the nixtamalization procedure, reduced the brightness and chroma of masa and tortilla and made these products seem darker and dull. [ABSTRACT FROM AUTHOR]

Phenolic acids profiles, chemical antioxidant activities (ABTS and ORAC), as well as cellular antioxidant activity (CAA) of tortilla of Mexican native maize landraces elaborated from nixtamalization and lime cooking extrusion processes were studied. Both cooking procedures decreased total phenolics, chemicals antioxidant activity when compared to raw grains. Extruded tortillas retained 79.6-83.5%, 74.1-77.6% and 79.8-80.5% of total phenolics, ABTS and ORAC values, respectively, compared to 47.8-49.8%, 41.3-42.3% and 43.7-44.4% assayed in traditional tortillas, respectively. Approximately 72.5-88.2% of ferulic acid in raw grains and their tortillas were in the bound form. Regarding of the CAA initially found in raw grains, the retained percentage for traditional and extruded tortillas ranged from 47.4 to 48.7% and 72.8 to 77.5%, respectively. These results suggest that Mexican maize landrace used in this study could be considered for the elaboration of nixtamalized and extruded food products with nutraceutical potential. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The stability of antioxidants in extruded and nixtamalized blue maize flours with calcium hydroxide [Ca(OH)] and calcium lactate [CHOCa] were evaluated. Extruded blue maize flours batches were obtained by mixing blue maize flours separately with different Ca(OH) (0.1, 0.2 and 0.3 %) and CHOCa (0.3, 0.6 and 0.9 %) concentrations respectively and extruded to obtain the extruded flours. For nixtamalized flours, the maize grains were cooked at 1 % Ca(OH) and 2.95 % CHOCa concentrations respectively. Color, antioxidant activity, total phenolics, total anthocyanins and individual anthocyanins, contents were analyzed. Color, antioxidant activity, anthocyanins contents and total phenolics decreased as the calcium hydroxide concentration increased. In contrast, increasing the calcium lactate concentration on the extruded flours had the opposite effect. The extrusion process retained 57-47 %, 72-62 % and 79-65 % of the anthocyanins content, total phenolic content and antioxidant activity, respectively. These retention rates were higher than those of the nixtamalized flours using the same calcium sources. Cyanidin-3-glucoside and pelargonidin-3-glucoside were identified in the maize kernel and flours. Cyanidin-3-glucoside concentration was increased by both extrusion and nixtamalization processed with either of the two calcium sources. In contrast, pelargonidin-3-glucoside concentration decreased by both processes. Other anthocyanins were observed, but they were not identified. [ABSTRACT FROM AUTHOR]

Nixtamalization, a key production step for masa flour used for tacos, corn tortillas, and chips, traditionally involves corn kernel cooking for 1 h and a lengthy process of steeping (16-18 h) in a lime solution. This study aimed at accelerating the traditional nixtamalization (TN) process using power ultrasound with acoustic energy density around 1.85 W/g for 1 h during cooking followed by brief steeping for 1 h. The cooked kernels (nixtamal) were evaluated for texture and color, while the cooking liquor (nejayote) was evaluated for solid losses. The power ultrasound-assisted nixtamalization resulted in significantly ( p ≤ 0.05) reduced process time and softer nixtamal with less solid losses in nejayote than control (TN). Response surface methodology established significant relationships of sonication duration and cooking temperature to texture, color of nixtamal, and dry matter loss in nejayote. This study indicates that power ultrasound ameliorated traditional nixtamalization in terms of quality and operation time. [ABSTRACT FROM AUTHOR]

Nixtamalization process is the first step to obtain maize based products, like tortillas; however, in both the traditional and commercial processes, white grain is generally preferred. Creole maize races, mainly pigmented varieties, have increasingly attention since these are rich in anthocyanins and carotenoids. The aim of this investigation was to evaluate the antioxidant and antimutagenic activity of rich anthocyanins and carotenoids extracts from creole maize races before (grain) and after (masa and tortilla) the nixtamalization process. Most anthocyanins and carotenoids were lost during nixtamalization. Before nixtamalization, blue and red genotypes contained either higher antioxidant capacity and anthocyanin contents (963 ± 10.0 and 212.36 ± 0.36 mg of cyanidin-3-glucoside eq/100 g, respectively) than the white and yellow genotypes. However, the highest carotenoid levels were displayed by red grains (1.01 ± 0.07 to 1.14 ± 0.08 μg of β-carotene eq/g extract). Anthocyanins losses were observed when the blue grains were processed into masa (83 %) and tortillas (64 %). Anthocyanins content correlated with antiradical activity ( r = 0.57) and with 2-aminoanthracene -induced mutagenicity inhibition on TA98 and TA100 ( r = −0.62 and r = −0.44, respectively). For white grains, nixtamalization also reduced carotenoids (53 to 56 %), but not antioxidant activity and 2-Aa-induced mutagenicity. Throughout the nixtamalization process steps, all the extracts showed antimutagenic activity against 2-aminoanthracene-induced mutagenicity (23 to 90 %), displaying higher potential to inhibit base changes mutations than frameshift mutations in the genome of the tasted microorganism (TA100 and TA98, respectively). The results suggest that even though there were pigment losses, creole maize pigments show antioxidant and antimutagenic activities after nixtamalization process. [ABSTRACT FROM AUTHOR]

The objective of the study was to obtain information on the chemical composition, functional properties, sensory quality and protein value of tortillas made from the nixtamalization of maize using either lime or wood ashes. The Ca, K, Mg, Fe, and Zn content of lime and wood ashes showed lime to be high in Ca content while wood ash contained more K and about 71% of the Ca content of lime. Both contained relatively high levels of Mg, Fe and Zn, but more so in the wood ashes. The level of reagent for nixtamalization was set at 0.8% of the maize weight. All other processing conditions were kept constant. The pH of the cooking solution was 12.0 for lime and 10.9 for wood ash. The moisture content of maize at 60 min of cooking was 45.8% for both treatments, however after 12 h of soaking, moisture level was 51.0% for the lime treatment and only 46.8% for the ash treatment. Solids (2.4%) in the lime cooking liquor were higher than in the wood ash liquor (1.0%). Chemical composition changes were similar between treatments in masa and tortilla; however, both masa and tortillas absorbed relatively high levels of all minerals including Fe and Zn from the wood ash treatment. The different treatment influenced functional properties particularly hardness and color. Tortilla characteristics were also similar. Protein quality of both alkali cooked products was lower than that of raw corn, more so the product from the wood ash treatment. Although some differences were observed in the sensory studies, human subjects did not dislike the wood ash made tortillas. [ABSTRACT FROM AUTHOR]

Starch is a polymer widely distributed in the nature and it is the principal component of cereals, tubers, legumes, and unripe fruits. Traditionally, starch has been isolated and used as raw material in diverse food products to produce or to improve specific functionalities and nowadays novel starches from unconventional sources have gained interest due to improved or due to different physicochemical and functional characteristics, especially for new food products. Recently, the potential nutraceutical characteristics of starchy products have increased the interest on this biopolymer. In this review, we describe the physicochemical and digestibility characteristics of starch present in diverse food crops namely maize and beans, and unconventional starch sources such as banana ( Musa paradisiaca L.), mango ( Mangifera indica L.), amaranth ( Amaranthus hypochondriacus), and barley ( Hordeum vulgare), among others. The starch after cooking, the storage of starchy products and the potential of starch isolated from unconventional sources to produce resistant starch-rich products using different treatments are emphasized. [ABSTRACT FROM AUTHOR]