Maize Dough Research Articles

Global de-trending significantly improves the accuracy of XGBoost-based county-level maize and soybean yield prediction in the Midwestern United States

ABSTRACT The application of machine learning in crop yield prediction has gained considerable traction, yet uncertainties persist regarding the impact of the yield trends on these predictions and the differences between the detrending methods. In our study, we utilized extreme gradient boosting (XGBoost) to scrutinize the effects of no trend processing (NTP), input year as a feature (IYF), input average yield as a feature (IAYF), input linear yield as a feature (ILYF), and the global detrending method (GDT) on the yield prediction of maize and soybean in the Midwestern United States. Based on our findings, compared with that of NTP, the incorporation of the yield trend as a predictor in XGBoost significantly improved the accuracy and reduced the uncertainty of the yield prediction. Notably, GDT emerged as a standout performer, significantly reducing the average yield prediction error by 0.091 t/ha for soybean and 0.158 t/ha for maize with respect to NTP, and concurrently improving the determination coefficient (R2) by 20.6% and 19.6% for soybean and maize, respectively. Compared with IYF, IAYF, and ILYF, GDT showed substantial improvements ranging from 3.8% to 12.7% in R2 for soybean and 3.6% to 12.7% for maize. The SHapley Additive ExPlanations (SHAP) framework showed that the enhanced vegetation index (EVI), particularly during the soybean podding and maize dough formation stages, played a crucial role in understanding the variations in interannual yield variability. These findings confirmed the importance of GDT in crop yield prediction via machine learning and could be used to facilitate future advancements in machine learning applications for yield forecasting.

Metaproteomics revealing microbial diversity and activity in the spontaneous fermentation of maize dough

Maize was spontaneously fermented and metaproteomic analysis was performed on the maize dough to investigate the profile of microbial communities. pH decreased (5.36, 4.44, and 4.42 after 24, 72, and 12 h), while lactic acid increased (0.03, 0.2, and 0.31 after 24, 72, and 120 h).The number of lactic acid bacteria (179 × 106 CFU/g) and mesophilic bacteria (213 × 106 CFU/g) was high. Based on metaproteomic analysis, Actinobacteria, Proteobacteria, and Firmicutes phyla dominated the fermentation medium, and the Actinobacteria was associated with the matrix of maize during starch degradation. Fermentation parameters (pH, lactic acid and titratable sugar) were considered to be regulated during the first 24 h of the fermentation process for ensure the microbiological safety of maize dough. Assuming that metaproteomics as culture-free methods can be an excellent tool for find mechanisms for faster optimization of a new product, is indeed a good tool for investigating fermentative microbiota.

Characterization and Functional Properties of Lactic Acid Bacteria Isolated from Fermented Maize Dough Used for the Preparation of Doklu

Lactic acid bacteria (LAB) has long been safely applied in the production of fermented foods and beverages. These bacteria are important for their contribution to food quality and also for their undeniable effects on health. In Africa, despite the abundance of isolated food sources and the diversity of identified microorganisms, the market for probiotics and functional foods based on selected local strains is almost non-existent. This paper aims to determine some technological properties of LAB isolates from fermented maize dough used for doklu production for potential application in food and probiotic products. A total of 25 LAB strains isolated from maize dough fermentation processes during doklu production were identified by 16S rDNA gene sequencing. Technological studies such as growth and acidification kinetics, diacetyl production, hydrogen peroxide production, and proteolytic activity were carried out. Their survival and growth under unfavorable conditions of temperature, salt concentration and pH were also analyzed. The isolates were identified as Pediococcus acidilactici (56%), Lactobacillus fermentum (24%), Pediococcus pentosaceus (12%) and Lactobacillus plantarum (8%). The technological properties of the LAB strains showed that 10 of them rapidly acidify the medium with pH variation (ΔpH) greater than 1 after 6 hours of fermentation. Good production of diacetyl and hydrogen peroxide, as well as good proteolytic activity, were obtained for several strains. Pediococcus acidilactici S15, S55, S56; Lactobacillus plantarum S32, S121 and Lactobacillus fermentum S44 showed the best technological properties. However, only 5 of them obtained good resistance following the various survival and growth under unfavorable conditions of temperature, salt concentration, and pH. This work has therefore demonstrated that the lactic acid bacteria involved in the natural fermentation of maize dough have interesting properties for various applications whether in the processing of food products as well as in the development of probiotic products.

Extruded finger millet improves rheology and quality of composite maize flatbread

Rising prevalence of celiac disease is driving the consumer toward alternative gluten-free flour for staple food making. Maize flour is gluten-free and widely consumed as unleavened flatbread (FB) in India. However, the quality of FB from maize dough is poor due to lack of gluten and viscoelasticity which causes difficulty in rolling, sheeting, and puffing. Research suggests that use of extruded flour can improve both technological and the functional quality of bread made from gluten-free flour. The present study evaluates the rheological and functional properties of the composite maize dough substituted with varying concentrations of extruded finger millet (EF). The pasting characteristics and the rheological properties of the composite flour were evaluated. An increased level of EF significantly enhanced the elastic character and textural properties of maize dough. The storage modulus (Gʹ) and loss modulus (G″) of the composite dough significantly increased compared with control dough. Sensory evaluation revealed that despite slight colour changes, in composite FB, the taste was at par with control. Results suggest that incorporation of extruded EF flour has the potential of improving the rheology, techno-functional and nutritional quality of maize based FB.

Functional, thermal, pasting, and rheological properties of gluten‐free maize composite flour: Effect of moth bean flour and hydrocolloid addition

Celiac disease is triggered by the consumption of gluten-rich foods that has emerged as a major global health problem. In fact, it is now important to look for an alternate and cheap source to develop a gluten-free diet using alternative ingredients. Therefore, the aim of the study was to evaluate the effect of moth bean flour and xanthan gum addition on the functional, thermal, pasting, and rheological properties of gluten-free maize dough. The results showed that the addition of moth bean and xanthan gum increased the functional (e.g., water absorption capacity of 1.89–2.52 g/g) and thermal (e.g., gelatinization onset temperature [To: 68.55–70.55°C] and enthalpy [ΔH: 1.66–2.89 J/g]) properties, while pasting properties varied. All formulations showed more solid-elastic than viscous behavior (G′ > G″) with tan δ < 1. Thus, the study concluded that the addition of protein source and hydrocolloid to maize flour can be a potential alternative to develop gluten-free bread and buns. Novelty impact statement Gluten-free flour blends were prepared with the mixture of maize flour, moth bean flour, and xanthan gum. Gluten-free flour blends mimicked viscoelastic properties of the gluten network and structural aspects of the gluten-rich dough. Gluten-free flour blends were found to be solid elastic-like behavior (G′ > G″). Gluten-free flour blends can be used in the preparation of baked products, such as bread.

Microbial Interactions between Amylolytic and Non-Amylolytic Lactic Acid Bacteria Strains Isolated during the Fermentation of Pozol.

Pozol is a Mexican beverage prepared from fermented nixtamalized maize dough. To contribute to understanding its complex microbial ecology, the effect of inoculating on MRS-starch pure and mixed cultures of amylolytic Sii-25124 and non-amylolytic W. confusa 17, isolated from pozol, were studied on their interactions and fermentation parameters. These were compared with L. plantarum A6, an amylolytic strain isolated from cassava. Microbial growth, kinetic parameters, amylolytic activity, lactic acid production, and hydrolysis products from starch fermentation were measured. The population dynamics were followed by qPCR. L. plantarum A6 showed higher enzymatic activity, lactic acid, biomass production, and kinetic parameters than pozol LAB in pure cultures. Mixed culture of each pozol LAB with L. plantarum A6 showed a significant decrease in amylolytic activity, lactic acid yield, specific growth rate, and specific rate of amylase production. The interaction between Sii-25124 and W. confusa 17 increased the global maximum specific growth rate (µ), the lactic acid yield from starch (Ylac/s), lactic acid yield from biomass (Ylac/x), and specific rate of lactic acid production (qlac) by 15, 30, 30, and 40%, respectively, compared with the pure culture of Sii-25124. Interactions between the two strains are essential for this fermentation.

Assessment of the quality of fresh nixtamalized maize doughs with different degrees of cooking and milling: A comparison of Mixolab and RVA analyses

Fresh nixtamalized maize dough (NMD) is commonly preferred by producers as raw material for the manufacture of a diversity of nixtamalized products. Based on the application, NMD may have different particle size distributions that may limit their analysis by common methods such as RVA. In the present study, we used the Mixolab to analyze fresh NMD produced with three degrees of cooking (undercooked, adequate cooked and overcooked) and milled to produce coarse, intermediate and fine doughs. Results were correlated with starch and tortilla features in order to evaluate the prediction of pregelatinization and starch damage occurring during processing, and with the quality of the final product. RVA was used for comparison purposes. Unlike RVA curves, Mixolab showed defined peak viscosities during heating independently of the milling degree of samples. Moreover, the Mixolab parameters showed strong correlations with the starch thermal properties, crystallinity, starch damage and lixiviated amylose. More correlations were obtained among Mixolab and RVA parameters in relationship with the attributes of tortillas. Results validated that the Mixolab is an efficient and rapid strategy to discern among different cooking degrees of fresh NMD independently of the particle size distribution, and may be useful to predict the quality of tortillas.

Assessment of Butter Adulteration Practices and Associated Food Safety Issues along the Supply Chain in Traditional Communities in the Central Highlands and Southwest Midlands of Ethiopia

Butter adulteration practices and their health risks were assessed along the supply chains in the central highlands and southwestern midlands of Ethiopia. A purposive sampling technique was used to select 1,101 respondents. Based on the results of the cross-sectional study, fatty acid profiles of butter samples collected from retailers' shops were investigated to determine the extent of adulteration and understand the risks of food safety. The assessment showed that an average of 94% of the respondents were aware of practices of butter adulteration. The common butter adulterants identified include different brands of hydrogenated vegetable oils, Irish potato puree, banana pulps, melted tallow, wheat and maize dough, and buttermilk, as well as water. The practice of adulteration significantly differed (P < 0.05) along the supply chain and increased from farm markets to the retail shops. Economically motivated adulteration is the main cause and resulted in up to 50% of butter spoilage. There were significant differences among the fatty acid profiles of pure butter; retailers' butter; pure butter intentionally adulterated with hydrogenated oil, potato puree, and banana pulp; and pure hydrogenated oil. The presence of methyl oleate, gondoic acid, and eicosadienoic acid in the retailers' butter might result from adulteration with hydrogenated oils and banana pulps. The study showed the presence of multiple-stage adulteration along the supply chain that could endanger the safety and quality of local butter. Policymakers and regulatory bodies in the area can use the information to improve the safety and quality of local butter along the supply chain.

Kinetics and mathematics modeling of ochratoxin a detoxification in maize dough by Lacticaseibacillus casei subs. casei subjected to continuous and pulsed ultrasound

The Lacticaseibacillus casei subsp. casei growth and ochratoxin A removal during fermentation of maize dough were mathematically modeled using the Baranyi and statistical models of Weibull and modified Gompertz models, respectively. The effect of important detoxification parameters including temperature level (35 and 37°C), sonication duration (0, 5, 10 and 15 min) as well as continuous/pulsed ultrasound treatment was investigated. According to the obtained results, the utilization of the pulsed sonication can improve the performance of the conducted treatment in comparison to the continuous case for 15 min duration of sonication. However, for lower periods of sonication (i.e., 5 and 10 min), the continuous sonication was proved to be more efficient in detoxification process. It was observed 2°C temperature increase lead to an average 4.33 µg/kg reduction of the Ochratoxin A after 48 hr fermentation from the sonication. Practical applications Microbial decontamination may give probable elimination of mycotoxins in food products under mild conditions, therefore preventive important losses in the quality of food products. Biological degradation of ochratoxin A under pulsed and continuous ultrasound was modeled. It was observed 2°C temperature increase lead to an average 4.33 µg/kg reduction of the Ochratoxin A after 48 hr fermentation from the sonication. Therefore, biological detoxification under optimal ultrasound treatment is an effective and rapid way to degrade ochratoxin A in maize dough.

Optimization of ethanol production using newly isolated ethanologenic yeasts

Yeasts are important microorganisms used for ethanol production; however, they are not equally efficient in the amount of ethanol production under different environmental conditions. It is, therefore, necessary to screen for elite strains to utilize them for commercial production of these commodities. In this study, yeasts were isolated from different Ethiopian traditional fermented alcoholic beverages (teji, tella, shamiata and areqe tinisis), milk and ergo, teff and maize dough, soil and compost, flowers, and fruits to evaluate their potential use for ethanol fermentation process. Isolates were screened for efficient ethanol production and the selected ones were identified using phenotypic and genetic characters using D1/D2 region of LSU rDNA sequence analysis. The yeast isolates were evaluated based on their growth and fermentation of different carbon sources. Response surface methodology (RSM) was applied to optimize temperature, pH and incubation time using central composite design (CCD) in Design-Expert 7.0.0. A total of 211 yeasts colonies were isolated of which 60% were ethanologenic yeasts (ethanol producers) and 40% were non-ethanol producers. The yeast population detected from various sources was in the range of 105CFU from traditional foods and beverages to that of 103CFU from fruits and soil samples. The data also showed that the number of colony types (diversity) did not correlate with population density. The highly fermentative isolates were taxonomically characterized into four genera, of which 65% of the isolates (ETP37, ETP50; ETP53, ETP89, ETP94) were categorized under Saccharomyces cerevisiae, and the remaining were Pichia fermentans ETP22, Kluyveromyces marxianus ETP87, and Candida humilis ETP122. The S. cerevisiae isolates produced ethanol (7.6-9.0 g/L) similar with K. marxianus ETP87 producing 7.97 g/L; comparable to the ethanol produced from commercial baker's yeast (8.43 g/L) from 20 g/L dextrose; whereas C. humilis ETP122 and P. fermentans ETP22 produced 5.37 g/L and 6.43 g/L ethanol, respectively. S. cerevisiae ETP53, K. marxianus ETP87, P. fermentans ETP22 and C. humilis ETP122 tolerated 10% extraneous ethanol but the percentage of ethanol tolerance considerably decreased upon 15%. S. cerevisiae ETP53 produced ethanol optimally at pH 5.0, 60 h, and 34oC. pH 4.8, temperature 36oC, and 65 h of time were optimal growth conditions of ethanol fermentation by K. marxianus ETP87. The ethanol fermentation conditions of P. fermentans ETP22 was similar to S. cerevisiae ETP53 though the ethanol titer of S. cerevisiae ETP53 was higher than P. fermentans ETP22. Therefore, S. cerevisiae ETP53, K. marxianus and P. fermentans ETP22 are good candidates for ethanol production.

Streptococcus infantarius 25124 isolated from pozol produces a high molecular weight amylopullulanase, a key enzyme for niche colonization

Abstract Pozol is a beverage made with maize dough that is prepared after boiling the kernels in limewater, causing a decrease in soluble sugars, with starch being the main fermentable carbohydrate in the dough. Previously, Streptococcus infantarius ssp. infantarius 25124 (Sii-25124) was identified as the most amylolytic bacteria isolated in this product. Analysis of Sii-25124 amylolytic enzymes revealed two amylases, a cytoplasmic α-amylase of 55.7 kDa and an extracellular amylopullulanase of 246.3 kDa, with two catalytic domains, one typical of an α-amylase and another typical of a pullulanase/glycogen debranching enzyme. Characterization of the joint activity of both enzymes using Sii-25124 cell lysate supernatant demonstrated stability between 30 °C and 45°C, and pH stability in a range between 6.8 and 8.0. The joint activity of Sii-25124 amylases showed a fast production of reducing sugars when starch was used as the substrate. In contrast, reducing sugar production from amylopectin was lower, but it steadily increased throughout the reaction time. The amylopullulanase produced by Sii-25124 hydrolyzes the starch in the dough to produce low molecular weight oligosaccharides, which may be transported into Sii-25124 cells, so that intracellular α-amylase hydrolyzes them to mono- and disaccharides. Amylopullulanase production by Sii-25124 could be an example of a specialized enzyme that successfully dominates starchy food fermentation.

Aflatoxins in maize dough and dietary exposure in rural populations of Togo

Aflatoxins are produced by fungi Aspergillus flavus and A. parasiticus which are found, among others, in sub-Saharan African countries in the tropical climate. Aflatoxins pose food safety challenges for many countries. They affect agricultural products, particularly cereals and are harmful to human. We investigated aflatoxin levels in maize dough, an ethnic maize-based food product, commonly consumed in Togo. The study also assessed health risks through dietary intake exposure of the rural populations in Togo. Seventy (70) samples from households in the southern rural region were collected and analyzed. Results showed that aflatoxins were present in approximately 76% of the samples tested and the levels ranged from 1.1 to 75.9 μg/kg. Aflatoxin B1 (AfB1) was generally the major contributor to total aflatoxins. Based on the results of a food consumption survey, children were the most exposed groups with an average exposure to AfB1 of maize dough ranging from 72.3 to 72.9 ng/kg pc/j to 700.8–701.2 ng/kg. bw/day for children, 61.9–62.4 to 463.1–463.4 ng/kg bw/day for women and 45.4–45.8 to 452.8–453.1 ng/kg bw/day for men. The assessment of an excess risk of liver cancer associated with AfB1 through the consumption of maize dough in the southern rural population of Togo was up to 57.85 per 100,000 children and 38.23 per 100,000 adults per year. The implications of these findings in the development of pathways and policies in reducing the total dietary exposure are discussed.

Tolerance to acid and alkali by Streptococcus infantarius subsp. infantarius strain 25124 isolated from fermented nixtamal dough: Pozol. Studies in APT broth

Pozol is a beverage prepared with maize dough made after boiling the kernels in limewater. This pretreatment could act as a selective force that shapes the starter microbiota, with microorganisms able to survive the fermentation. Since Streptococcus infantarius subsp. infantarius (Sii) dominates in pozol, we evaluated the effect of acid and alkali stresses on strain Sii-25124 in commercial APT broth as a first attempt to assess its adaptation capacity. Results suggest that Sii-25124 has adaptative advantages to pH changes that possibly contribute to its persistence even after the acidification of the dough. Its cardinal pH values were 4.0 and 11.0, with an optimum between 6.6 and 8.0. It showed alkali tolerance unlike other pozol Sii strains. Adaptation at pH 4.0, 10.0 and 11.0, compared with non-adapted cells, induced acid tolerance enhancing survival at pH 3.6 (P < 0.05); a 2 min heat shock at 62 °C induced alkali tolerance response enhancing survival at pH 10.5 (P < 0.05). The up-regulation of dnaK, groEL, ptsG and atpB was observed during 5 h of exposition at pH 3.6, 4.0 and 10.0, showing similar expression rates after induction by acid shock or alkaline stress. Changes of atpB were more evident having almost five-fold induction during long-term stress.

Efecto de la adición de antocianinas a masa de maíz azul sobre color, textura y capacidad antioxidante de tortilla

Introduction: Anthocyanins of maize in microcapsules (MC) can be added in maize dough to modify color and antioxidants in tortillas and derivatives. Objective: To evaluate the addition of anthocyanins of maize in MC or extract (EL) to blue-purple maize dough on color, texture, total soluble phenols (TSP), total anthocyanins content (TAC) and antioxidant capacity (AC) of maize tortillas. Methodology: Different concentrations (0.5, 0.75 and 1.0 %) of MC or EL anthocyanins were added to bluepurple maize dough (Bolita). Blue tortilla made with Chalqueño maize (traditional) was used as reference for color and AC. Results: The tortilla with 0.75 and 1.0 % MC had red-purple hue, and with EL the tortilla showed red-orange hues. When cooking the tortilla, it lost 39 to 49.1 % of anthocyanins, regardless of how anthocyanins were added to the dough (MC or EL). The hardness of the tortilla increased with addition of anthocyanins in EL, but not in MC. The addition of anthocyanins increased TAC and TSP. AC of the tortilla in the pigment treatments was higher (P ≤ 0.05) compared to the control and reference. Study limitations: Results may change depending on the blue-purple maize grain used. Originality: There are no reports of similar studies. Conclusions: The addition of low amounts of anthocyanins (&lt; 2 mg) to the blue-purple maize dough produces tortillas similar in color to traditional blue maize tortillas, and with higher AC.

Influence of dough sheeting, flour pre-gelatinization and zein inclusion on maize bread dough functionality

Developing tropical countries need simple technologies to enable the production of bread from locally produced cereals, such as maize and sorghum. However, current gluten-free bread making technology relies heavily on the addition of additives, which results in products that are nutritionally inferior to wheat breads. Hence, this study investigated the technologies of flour pre-gelatinization and dough sheeting plus addition of commercial zein to improve maize dough functionality and bread quality. A strong and cohesive maize flour dough could be produced as a result of uniform incorporation of a 30% of pre-gelatinized maize flour through repeated dough sheeting. Pre-gelatinized starch acts as a hydrocolloid and the dough viscosity was probably increased through the hydroxyl groups of the hydrocolloidal structure enabling more interactions with water molecules. The dough still lacked extensibility. However, extensibility and gas-holding were significantly improved by additionally incorporating an α-zein viscoelastic mass above its glass transition temperature into the dough during sheeting. The zein fibrils appeared to entrap the maize flour particles. Zein inclusion also improved bread crumb cell structure and increased loaf volume somewhat. However, the crumb cell walls were much thicker than in wheat bread and comprised clumps of starch granules.

Lactic Acid Fermentation of Arabinoxylan From Nejayote by Streptococcus infantarius ssp. infantarius 25124 Isolated From Pozol.

Streptococcus infantarius ssp. infantarius 25124 (Sii-25124) is a lactic acid bacterium (LAB) isolated from pozol, a refreshing beverage prepared by suspending fermented nixtamal (a thermal and alkali-treated maize dough) in water. Although Lactobacillus are the predominant strains in fermented doughs, such as sourdoughs, and non-nixtamalized fermented maize foods, the pozol microbiota is markedly different. This may be the result of the nixtamalization process, which could act as a selective force of some strains. Sii-25124 has been reported as the main amylolytic LAB in pozol; starch is the primary carbon source on nixtamal since monosaccharides and disaccharides are lost during nixtamalization; however, non-amylolytic LAB counts are higher than amylolytic LAB in pozol after 24-h fermentation suggesting that another carbon source is being used by the former bacteria. Hemicellulose (arabinoxylan in maize) becomes available via nixtamalization and is subsequently metabolized by LAB. The aim of this work was to determine whether this bacterium is able to use arabinoxylan as the only carbon source in a defined medium containing arabinoxylan extracted from either nejayote (wash water produced during nixtamal preparation), or beechwood xylan. Xylanase activity in the presence of nejayote arabinoxylan (135.8 ± 48.7 IU/mg protein) was higher than that of beechwood (62.5 ± 19.8 IU/mg protein). Other enzymatic activities, such as arabinofuranosidase and acetyl esterase, were also detected, suggesting the adaptation of the bacterium studied to nixtamal dough. It was concluded that Streptococcus infantarius 25124 isolated from pozol was able to use arabinoxylans, which are present in nixtamal dough, so fermentation does not depend exclusively on free sugars and starch.

Application of apigeninidin-rich red sorghum biocolorant in a fermented food improves product quality.

BACKGROUNDThe ‘clean label’ trend is pushing the food industry to replace synthetic colorants with plant‐based colorants. However, technological efficacy and undesirable side effects restrict the use of plant‐based colorants in industrial applications. This research studied the production of fermented maize dough coloured by apigeninidin‐rich red sorghum biocolorant, as practised for centuries in West Africa, as a model to assess the impact of the biocolorant on nutritional and sensorial quality of foods.RESULTSA 3‐day fermentation of a dyed maize dough (containing 327 µg g−1 dry matter of apigeninidin) by Pichia kudriavzevii and Lactobacillus fermentum led to a degradation of 69% of the apigeninidin content, causing a clearly visible colour difference (ΔE*00 17.4). The antioxidant activity of fermented dyed dough (DD) increased by 51% compared to fermented non‐dyed dough (NDD). However, the phytate dephosphorylation and volatile organic compound concentrations were lower in DD than in NDD. This suggests a lower mineral solubility and change in the sensory quality of fermented DD.CONCLUSIONApigeninidin extract from sorghum leaf sheaths proved to be a bioactive red biocolorant with potential in fermented foods. The formation of new antioxidant compounds needs further investigation, as does the impact on the development of volatile compounds. © 2018 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evaluation of xylan as carbon source for Weissella spp., a predominant strain in pozol fermentation

Pozol is a traditional Mexican refreshing acid beverage made of hot-alkali treated and fermented maize dough. It has been demonstrated that non-amylolytic lactic acid bacteria as Weissella sp. are important in this process. The aim of this work was to study Weissella spp. strains isolated from pozol from the carbon source perspective. For this purpose, Weissella confusa L9, W. confusa L17, W. confusa Snc40, W. paramesenteroides 3a and W. cibaria 3LA were studied. All the microorganisms were able to metabolize xylose; they also showed β-glucosidase and β-galactosidase activities. The ability to grow in xylan was tested; all the strains showed maximum growth at 24 h but W. confusa L9, W. confusa L17 and W. confusa Snc40 grew from 7.09 to 8.66, 7.08 to 7.84 and 7.26 to 7.94 Log CFU/ml, respectively. W. confusa L9 growth in partially hydrolyzed xylan was evaluated. The evolution of xylooligosaccharides throughout the fermentation was performed. Xylose accumulation was observed (0.28–0.28 mg/ml at 24 h). A preference for xylobiose and xylotriose was observed. β-xylosidase activity was found in W. confusa L9 since consumption of xylooligosaccharides by this microorganism was demonstrated. Hemicellulose is therefore an alternative carbon source sustaining pozol fermentation.

Effect of Different Corn Processing Techniques in the Nutritional Composition of Nixtamalized Corn Tortillas

Maize in the form of tortilla plays an important role in the diet of Mexican population, with a per capita consumption of 157 g/day. The two main methods for tortilla are the traditional method, which uses maize dough or masa made in the ancient manner; and the industrial method, which uses industrially-processed maize flour. Both methods are based on the alkaline-processing of maize known as nixtamalization. Chemical profiles of maize tortillas were analyzed. Samples were collected between 2012 and 2013 in three lots, one every six months, from four retail shops at 16 municipalities of Mexico City; tortillas made of maize flour were obtained from two supermarkets of four municipalities. Composition changed according to raw materials and production method. Samples made with nixtamal dough showed lower contents of moisture, of about 5%, and absence of thiamine and riboflavin than nixtamal flour. Differences in carbohydrates and iron, 0.5% more in case of iron, may be caused by maize phenotype; while differences in crude fat 1% more, dietary fiber 0.5% more, thiamine, and riboflavin are due to additives added by manufacturers; however, concentration of vitamins and minerals in the final product were below theoretical values. In case of calcium, 100% more in maize dough tortillas is due to lime amount added on each method or amount of broken grain processed. Regarding on effect of sampling, contents of protein and crude fat remained constant on dough tortillas regardless of sample collection and these were consistently higher than maize flour tortillas over time, 0.3% and 1%, respectively, which is due to maize phenotype. On flour-made tortillas, fat and dietary fibers were also constant since maize flour manufacturers add additives and nutrients to obtain certain rheological characteristics and nutritional content on maize flour tortillas.

Textural, chemical and sensorial properties of maize tortillas fortified with nontoxic Jatropha curcas L. flour

ABSTRACTHunger and malnutrition still affecting part of the Mexican population, for whom the tortilla is a staple food. However, maize tortillas are high in calories but deficient in proteins; therefore, studies have been conducted to fortify tortillas, with protein-rich nonconventional sources. This study examines the physicochemical and rheological characteristics of dough and maize tortillas fortified with nontoxic Jatropha curcas flour. Fortified maize doughs were prepared with 0%, 5%, 10%, 15% and 20% J. curcas nontoxic flour, which contains 55% protein. Tortillas were made and their chemical profile and tortilla quality were quantified and subjected to sensorial analysis. Rheological characteristics of dough were slightly modified but the protein in the tortillas increased 10.8% with treatment T20. They did not change in color, were soft, and consumer acceptance was not affected. It is concluded that nontoxic J. curcas flour is an excellent option for increasing the protein value of tortillas.