High-energy alkaline milling as a potential physical and chemical cornstarch ecofriendly treatment to produce nixtamalized flours.

In this study, hard corn grains were nixtamalized (alkali-heat treatment) by a high-energy ball mill to investigate the effects on its physicochemical, textural, and microstructural properties. Ball milling modifies the structure and properties of cornstarch. The gelatinization peak of starch was evidenced and thermal and pasting properties were significantly affected. With regard to rheological properties, the viscosity peak increased from 2454 cP in traditional nixtamalized flour to 4294 cP in high-energy milling treatments with 1.4% of Ca(OH)2 and 20% moisture content, C1.4, while enthalpy ranged from 3.5 to 0.34 J/g, respectively. High-energy milling influenced the Fourier-Transform InfraRed Spectroscopic (FT-IR) patterns. All of the samples of the corn-grain starches presented the typical A-type X-ray diffraction pattern. The crystallinity of starch from CG showed a lower intensity in peaks 2θ ~ 15 and 23° compared with starch from WG and YG. The textural properties of the masas were influenced, adhesiveness was reduced, but cohesiveness was increased by the addition of Ca(OH)2. In the structural characterization by E-SEM, the control presented a greater amount of agglomerated starch granules, followed by the high-energy milling treatments. The results suggest that high-energy alkaline milling could be a potential physical and chemical method to modify corn-starch properties and obtain nixtamalized products.

Effect of High-Energy Milling on Bioactive Compounds and Antioxidant Capacity in Nixtamalized Creole Corn Flours.

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-ß-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.

Physico-chemical, thermal, and rheological properties of nixtamalized creole corn flours produced by high-energy milling.

High-energy milling (HEM) was used to produce nixtamalized corn flours, the traditional nixtamalization process was used as a control. Four creole grains were stone-milled, adjusted to an appropriate moisture content and calcium hydroxide concentration and milled using HEM. The physicochemical, thermal, and rheological characteristics of the flours and corn masas were affected by the HEM process. Negritas and Ahualulco creole grains nixtamalized by HEM showed similar viscosity profiles as a control. HEM reduced the gelatinization enthalpy compared to control and raw flours. Diffractograms showed changes in the crystalline structures and FT-IR demonstrated different regions for lipids, proteins, and carbohydrates in all control and treated grains. The texture of corn masas revealed significant differences according to the grain type. ESEM analysis showed smaller particles of HEM flours compared to those of the control. HEM could be a faster, non-pollutant, energy-saving, alternative nixtamalization process.

Physicochemical, thermal, and rheological properties of nixtamalized blue-corn flours and masas added with huitlacoche (Ustilago maydis) paste.

The aim of this work was to evaluate the effect of the addition of huitlacoche paste to nixtamalized blue-corn flours (NBCF) on the physicochemical, thermal, and rheological properties of masas. Raw blue maize was nixtamalized (hydrothermal alkalinized process), then was wet-milled in a stone mill, masa was dehydrated, pulverized and sieved to obtain NBCF; commercial nixtamalized blue-corn flour (CNBCF) was used as a control. Huitlacoche paste in concentrations of 3, 6, 9, 12, 15, and 18% was added to nixtamalized flours. Characteristics of the blue grain showed its great effects on water absorption, viscosity, and masa cohesiveness; the addition of huitlacoche significantly influenced adhesiveness, water-absorption, color, and the rheological properties (p < 0.05). Values between 0.03 and 0.083 kg-force resulted in masas with optimal adhesiveness. The inclusion of huitlacoche paste can be achieved with a maximal addition of 9% in NBCF for an industrial process and could comprise a new industrialization alternative.

Phytophthora capsici epidemic dispersion on commercial pepper fields in Aguascalientes, Mexico.

Chili pepper blight observed on pepper farms from north Aguascalientes was monitored for the presence of Phytophthora capsici during 2008-2010. Initially, ELISA tests were directed to plant samples from greenhouses and rustic nurseries, showing an 86% of positive samples. Later, samples of wilted plants from the farms during the first survey were tested with ELISA. The subsequent survey on soil samples included mycelia isolation and PCR amplification of a 560 bp fragment of ITS-specific DNA sequence of P. capsici. Data was analyzed according to four geographical areas defined by coordinates to ease the dispersal assessment. In general, one-third of the samples from surveyed fields contained P. capsici, inferring that this may be the pathogen responsible of the observed wilt. Nevertheless, only five sites from a total of 92 were consistently negative to P. capsici. The presence of this pathogen was detected through ELISA and confirmed through PCR. The other two-thirds of the negative samples may be attributable to Fusarium and Rhizoctonia, both isolated instead of Phytophthora in these areas. Due to these striking results, this information would be of interest for local plant protection committees and farmers to avoid further dispersal of pathogens to new lands.

Chemical and biochemical changes in prickly pears with different ripening behaviour.

Chemical and biochemical changes were studied in ripening prickly pears from three Opuntia morphospecies with different ripening behaviour: Naranjona (O. ficus-indica), Blanca Cristalina (Opuntia sp.), and Charola (O. streptacantha), of early, intermediate, and late ripening, respectively. At fullyripe stage (commercial maturity), Blanca Cristalina showed the biggest fruits, the hardest texture, and its pulp had the highest protein content. There were no significant differences among morphospecies in pH or total soluble solids in fully ripe fruits. The three species exhibited considerable levels of vitamin C, dietary fibre, and minerals such as calcium, iron, and zinc. Protein expression was analysed in pulp and skin from every species at physiological and commercial maturity. Some proteins appeared at both stages, while many others expressed differentially. This study evaluated prickly pear components important for human nutrition and health, and provided basic information on pricky pear ripening, with a view to its control and to improving shelf life.