Bio-based biodegradable film to replace the standard polyethylene cover for silage conservation.

The research was aimed at studying whether the polyethylene (PE) film currently used to cover maize silage could be replaced with bio-based biodegradable films, and at determining the effects on the fermentative and microbiological quality of the resulting silages in laboratory silo conditions. Biodegradable plastic film made in 2 different formulations, MB1 and MB2, was compared with a conventional 120-µm-thick PE film. A whole maize crop was chopped; ensiled in MB1, MB2, and PE plastic bags, 12.5kg of fresh weight per bag; and opened after 170d of conservation. At silo opening, the microbial and fermentative quality of the silage was analyzed in the uppermost layer (0 to 50mm from the surface) and in the whole mass of the silo. All the silages were well fermented with little differences in fermentative quality between the treatments, although differences in the mold count and aerobic stability were observed in trial 1 for the MB1 silage. These results have shown the possibility of successfully developing a biodegradable cover for silage for up to 6mo after ensiling. The MB2 film allowed a good silage quality to be obtained even in the uppermost part of the silage close to the plastic film up to 170d of conservation, with similar results to those obtained with the PE film. The promising results of this experiment indicate that the development of new degradable materials to cover silage till 6mo after ensiling could be possible.

Designing a high-yielding maize ideotype for a changing climate in Lombardy plain (northern Italy).

The expected climate change will affect the maize yields in view of air temperature increase and scarce water availability. The application of biophysical models offers the chance to design a drought-resistant ideotype and to assist plant breeders and agronomists in the assessment of its suitability in future scenarios. The aim of the present work was to perform a model-based estimation of the yields of two hybrids, current vs ideotype, under future climate scenarios (2030-2060 and 2070-2100) in Lombardy (northern Italy), testing two options of irrigation (small amount at fixed dates vs optimal water supply), nitrogen (N) fertilization (300 vs 400 kg N ha(-1)), and crop cycle durations (current vs extended). For the designing of the ideotype we set several parameters of the ARMOSA process-based crop model: the root elongation rate and maximum depth, stomatal resistance, four stage-specific crop coefficients for the actual transpiration estimation, and drought tolerance factor. The work findings indicated that the current hybrid ensures good production only with high irrigation amount (245-565 mm y(-1)). With respect to the current hybrid, the ideotype will require less irrigation water (-13%, p<0.01) and it resulted in significantly higher yield under water stress condition (+15%, p<0.01) and optimal water supply (+2%, p<0.05). The elongated cycle has a positive effect on yield under any combination of options. Moreover, higher yields projected for the ideotype implicate more crop residues to be incorporated into the soil, which are positively correlated with the SOC sequestration and negatively with N leaching. The crop N uptake is expected to be adequate in view of higher rate of soil mineralization; the N fertilization rate of 400 kg N ha(-1) will involve significant increasing of grain yield, and it is expected to involve a higher rate of SOC sequestration.

Technical considerations for maize flour and corn meal fortification in public health: consultation rationale and summary.

Fortification is the purposeful addition of vitamins and minerals to foods during their industrial processing, as a way to improve the nutrition and health of populations who consume these foods. Twelve countries have mandatory maize (Zea mays subsp. Mays) flour or meal fortification. The World Health Organization (WHO) is updating evidence-informed guidelines for the fortification of staple foods in public health, including the fortification of maize flour and corn meal with iron and other micronutrients. Although there is limited experience with fortification of maize, mass fortification of maize flour with at least iron has been practiced for many years in several countries in the Americas and Africa: Brazil, Costa Rica, El Salvador, Kenya, Mexico, Nigeria, Rwanda, South Africa, Tanzania, Uganda, the United States, and Venezuela. The WHO, in collaboration with the Sackler Institute for Nutrition Science and the Flour Fortification Initiative (FFI), convened a consultation on technical considerations for fortification of maize flour and corn meal in public health in New York, New York on April 8-9, 2013 to provide input into the guideline-development process and to discuss technical considerations of the fortification processes for maize flour and corn meal.

Legislative frameworks for corn flour and maize meal fortification.

Corn flour and maize meal fortification can benefit the consumer when the added nutrient contents are in amounts appropriate to address nutrient gaps. Legislative instruments (standards and regulations) are needed to provide guidance to the producers and food control authorities. We reviewed a number of national standards and regulations of fortified corn flour and maize meal and identified constraints; contrary to current belief, the practice of using minimum contents or ranges of nutrients has caused confusion, misinterpretation, and conflict, and should therefore be abandoned. On the basis of the findings, a model of fortification legislation is proposed, in which the additional content and the expected average nutrient content in a final product are recommended as the main parameters for quality control and enforcement. For labeling, the average content, or one adjusted to the expected content of the product at the market, can be applied. Variation in micronutrient contents should still be checked to ensure homogeneity but with adherence to clear procedures of sampling and testing, which should be part of the standards and regulations.

Stability of key micronutrients added to fortified maize flours and corn meal.

Maize is a dietary staple in many countries. Although nutritious in many ways and a good source of energy, typical maize lacks several key micronutrients (MNs) that are often added to maize meals or flours to enhance nutritional value. Many factors affect MN stability in maize products, including uncontrolled conditions during distribution, long storage times, and MN premix composition. Consumer preparation also affects the final MN content of food. This review summarizes research relating to MN stability during processing, transport, storage, and meal preparation, focusing on those MNs most often added to maize and maize-based foods. Significant losses in B vitamins (B1, B2, B3, B6, B9, and B12) occur during manufacturing, distribution, and cooking. Added minerals (e.g., iron, zinc, calcium) are generally retained, although phytates in corn may affect bioavailability. Vitamins A and D3 are recent additions to fortification premixes for maize and are not well studied. Although there have been numerous studies of MN fortification in wheat flour, maize has not been as thoroughly examined, so recommendations are not as well supported. Future investigations should include well-designed and executed studies of the most labile MNs added to maize flours and meals, and their fate during all steps of processing, shipping, and preparation.

Global risk assessment of aflatoxins in maize and peanuts: are regulatory standards adequately protective?

The aflatoxins are a group of fungal metabolites that contaminate a variety of staple crops, including maize and peanuts, and cause an array of acute and chronic human health effects. Aflatoxin B1 in particular is a potent liver carcinogen, and hepatocellular carcinoma (HCC) risk is multiplicatively higher for individuals exposed to both aflatoxin and chronic infection with hepatitis B virus (HBV). In this work, we sought to answer the question: do current aflatoxin regulatory standards around the world adequately protect human health? Depending upon the level of protection desired, the answer to this question varies. Currently, most nations have a maximum tolerable level of total aflatoxins in maize and peanuts ranging from 4 to 20ng/g. If the level of protection desired is that aflatoxin exposures would not increase lifetime HCC risk by more than 1 in 100,000 cases in the population, then most current regulatory standards are not adequately protective even if enforced, especially in low-income countries where large amounts of maize and peanuts are consumed and HBV prevalence is high. At the protection level of 1 in 10,000 lifetime HCC cases in the population, however, almost all aflatoxin regulations worldwide are adequately protective, with the exception of several nations in Africa and Latin America.

Producción de micotoxinas por aislamientos de Aspergillus niger procedentes de muestras de maíz recogido en tres regiones portuguesas / Mycotoxin production by Aspergillus niger aggregate strains isolated from harvested maize in three Portuguese regions

Antecedentes. En todo el mundo se considera que el maíz es uno de los cereales más vulnerables a las micotoxinas. Dos de las asociadas con más frecuencia a este cereal son las fumonisinas y la ocratoxina A. Se sabe que A. niger produce ocratoxina A, que suele estar presente en el maíz. Sin embargo, recientemente, se ha descrito que A. niger puede producir fumonisinas, principalmente fumonisina B2. Objetivos. El objetivo del presente estudio fue aislar las cepas de Aspergillus niger a partir de muestras de maíz provenientes de la siega en tres regiones agrícolas portuguesas y detectar la producción de fumonisina B2 y ocratoxina A. Métodos. Se obtuvieron 95 muestras de maíz de la siega en estas regiones, se sembraron en placas y se aislaron todas las cepas de Aspergillus sección Nigri observadas. Se caracterizaron morfológicamente las cepas y se determinó la producción de micotoxinas mediante cromatografía líquida de alto rendimiento con detección de fluorescencia. Resultados. Se aislaron un total de 270 cepas de Aspergillus sección Nigri de 73 muestras (77% de las muestras). Se observó que alrededor del 14% de las cepas producían ocratoxina A, mientras que aproximadamente el 39% producían fumonisina B2. Conclusiones. No pudo identificarse una asociación entre la producción de estas dos micotoxinas y no pudimos extraer conclusiones sobre si la presencia de cepas de A. niger aumentará el riesgo de contaminación del maíz por fumonisinas, en especial por fumonisina B2(AU)

Background. Maize is considered one of the crops more susceptible to mycotoxins in the world. Two of the mycotoxins commonly associated with maize are fumonisins and ochratoxin A. Aspergillus niger is a known producer of ochratoxin A and is easily found in maize. Recently, however, A. niger has been reported to produce as well fumonisins, mainly fumonisin B2. Aims. The aim of this study was to isolate A. niger strains from maize samples collected in three Portuguese maize growing regions and to detect the production of both fumonisin B2 and ochratoxin A. Methods. Ninety five maize samples were collected, plated, and all observable Aspergillus section Nigri strains were isolated. Strains were morphologically characterized and mycotoxin production was determined by HPLC-FD. Results. Isolations resulted in a total of 270 strains of black Aspergillus from 73 samples (77% of the samples). About 14% of those strains were found to produce ochratoxin A and 39% of the strains were found to produce fumonisin B2. Conclusions. An association between the production of these two mycotoxins could not be found and no conclusions could be taken whether the presence of A. niger aggregate strains will increase the risk of maize contamination with fumonisins and more specifically with fumonisin B2(AU)

Effect of applying inoculants with heterolactic or homolactic and heterolactic bacteria on the fermentation and quality of corn silage.

This study examined the effect of applying different bacterial inoculants on the fermentation and quality of corn silage. Corn plants were harvested at 35% DM, chopped, and ensiled in 20-L mini silos after application of (1) deionized water (CON) or inoculants containing (2) 1 × 10(5) cfu/g of Pediococcus pentosaceus 12455 and Propionibacteria freudenreichii (B2); (3) 4 × 10(5) cfu/g of Lactobacillus buchneri 40788 (BUC); or (4) 1 × 10(5) cfu/g of Pediococcus pentosaceus 12455 and 4 × 10(5) cfu/g of L. buchneri 40788 (B500). Four replicates of each treatment were weighed into polyethylene bags within 20-L mini silos. Silos were stored for 575 d at ambient temperature (25°C) in a covered barn. After silos were opened, aerobic stability, chemical composition, and yeast and mold counts were determined. The DNA in treated and untreated silages was extracted using lysozyme/sodium dodecyl sulfate lysis and phenol/chloroform and used as a template for a conventional PCR with primers designed on the 16S rRNA gene to detect the presence of L. buchneri in all silage samples. Acetic acid concentration was greater in B2 silages versus others (6.46 vs. 4.23% DM). Silages treated with BUC and B500 had lower pH and propionic acid concentration and greater lactic acid concentration than others. The B500 silage had the greatest lactic:acetic acid ratio (1.54 vs. 0.41), and only treatment with BUC reduced DM losses (5.0 vs. 14.3%). Yeast and mold counts were less than the threshold (10(5)) typically associated with silage spoilage and did not differ among treatments. Consequently, all silages were very stable (>250 h). Aerobic stability was not improved by any inoculant but was lower in B500 silages versus others (276 vs. 386 h). The conventional PCR confirmed the presence of similar populations of L. buchneri in all silages. This may have contributed to the prolonged aerobic stability of all silages.

Safe composition levels of transgenic crops assessed via a clinical medicine model.

Substantial equivalence has become established as a foundation concept in the safety evaluation of transgenic crops. In the case of a food and feed crop, no single variety is considered the standard for safety or nutrition, so the substantial equivalence of transgenic crops is investigated relative to the array of commercial crop varieties with a history of safe consumption. Although used extensively in clinical medicine to compare new generic drugs with brand-name drugs, equivalence limits are shown to be a poor model for comparing transgenic crops with an array of reference crop varieties. We suggest an alternate model, also analogous to that used in clinical medicine, where reference intervals are constructed for a healthy heterogeneous population. Specifically, we advocate the use of distribution-free tolerance intervals calculated across a large amount of publicly available compositional data such as is found in the International Life Sciences Institute Crop Composition Database.

[Medical and biological safety assessment of genetically modified maize strain MIR604].

The results of toxicologo-hygienic examinations, which were conducted within the framework of integrated medical and biological assessment of genetically modified rootworm Diabrotica spp.-protected maize event MIR604, are presented. Analysis of morphological, hematological, biochemical parameters and system (sensitive) biomarkers has not confirmed any toxic effect of maize event MIR604.

[Medical and biological safety assessment of genetically modified maize event MIR604].

There are presented the results of genotoxicologic, immunologic and allergologic examinations which were conducted within the framework of integrated medical and biological assessment of genetically modified rootworm Diabrotica spp.-protected maize event MIR604. Analysis of damages of DNA and structural chromosome aberrations, assessment of the allergenic potential and immunoreactive properties has not confirmed any genotoxic, allergenic and immunotoxic effect of maize event MIR604.

Evaluation of the lime-cooking and tortilla making properties of quality protein maize hybrids grown in Mexico.

Eleven experimental and three commercial white quality protein maize (QPM) hybrids and two regular endosperm controls were planted at Celaya, Guanajuato, Mexico with the aim of comparing grain physical characteristics, protein quality, lime-cooking and tortilla making properties. All genotypes were planted under irrigation using a density of 80,000 plants/ha and fertilized with 250 kg N-60 P-60 K per hectare. When compared with the controls these QPM genotypes had lower test (77.4 vs. 76.5 kg/hL) and 1,000 kernel weights (327 vs. 307 g), softer endosperm texture (2.5 vs. 1.8 where 1 = soft, 2 intermediate and 3 hard endosperm), lower protein (10.0 vs. 8.0%), higher nixtamal water uptake after 30 min lime-cooking (50.0 vs. 53.1% moisture) and lower pericarp removal scores. The lower thousand-kernel weight and softer endosperm texture observed in the QPM genotypes lowered the optimum lime-cooking time as estimated with regression equations. Most QPM genotypes had higher amounts of lysine, tryptophan and albumins/globulins when compared with the controls. QPMs HEC 424973, HEC 774986 and HEC 734286 had the best grain traits for nixtamalization and therefore the best potential for industrial utilization. The commercial use of these QPM hybrids should benefit Mexicans who depend on tortillas as the main staple.

Relationship between structural and biochemical characteristics and texture of corn grains.

The texture of corn grains is a fundamental characteristic for the industry as well as for grain producers and processors. To further understand the mechanisms involved in grain hardness, contrasting corn cultivars for grain hardness and protein quality were evaluated. The cultivars were Cateto L237/67 (hard endosperm and low protein value), QPM BR 451 (semi-hard endosperm and high protein value); Bolivia-2 (floury endosperm and low protein value), and Opaque-2 (floury endosperm and high protein value). Evaluations were carried out at 10, 20, 30, 40, 50, and 60 days after pollination in developing corn grains and in the mature grain. In developing grains, evaluation consisted in the determination of the area, percentage of starch granules, distribution of starch granules, and protein bodies in the endosperm. In mature corn grains, the parameters evaluated were: density, percentage of total proteins, levels of lysine and tryptophan, and banding pattern of zeins. The results indicate that the higher physical resistance of corn grains from the cultivars analyzed is influenced by the high percentage of total proteins, high synthesis of 27-kDa zeins, presence of protein bodies, and perfect organization of starch granules in the endosperm, independent of their sizes.

Determination of fumonisins B1 and B2 in corn by liquid chromatography/mass spectrometry with immunoaffinity column cleanup: single-laboratory method validation.

A single-laboratory method validation was conducted to establish the effectiveness of an immunoaffinity column cleanup procedure followed by liquid chromatography/mass spectrometry (LCIMS) for the determination of fumonisins B1 and B2 (FBI + FB2) in corn. The test portion is extracted with acetonitrile-methanol-water (25 + 25 + 50). The extract is filtered, diluted with phosphate-buffered saline solution, and applied to an immunoaffinity column. FB1 + FB2 are removed with methanol and directly determined by reversed-phase LC with MS detection using selected-ion monitoring of 2 characteristic ions in each case. Test portions of blank corn samples were spiked with a mixture of FB1 + FB2 to give total levels of 200 and 500 ng/g, respectively. Recoveries of both FB1 and FB2 from spiked samples averaged 90.4-101%. Based on results for spiked raw corn (triplicates at 2 levels), the relative standard deviation for repeatability ranged from 2.8 to 7.1%. The accuracy of the method was demonstrated by analysis of Food Analysis Performance Assessment Scheme (FAPAS) test material. The method was also applied to a small survey of processed corn products such as corn chips, cornflakes, and popcorn.

[The effect of consuming quality protein maize or conventional maize on the growth and morbidity of malnourished Nicaraguan children 1 to 5 years of age]. / Efectos de la ingesta de maíz de alta calidad de proteína (QPM) versus maíz convencional en el crecimiento y la morbilidad de niños nicaragüenses desnutridos de 1 a 5 años de edad.

Quality protein maize (QPM), with twice the amount of tryptophan and lysine than conventional maize, has improved the nutritional status of severely malnourished children. This double-blind clinical study evaluated the impact of QPM on the growth and morbidity of mild and moderately malnourished children. In a Nicaraguan day care center, 48 children 1 to 5 years old who were malnourished (> 2 indicators with < -1 Z for weight-age, height-age or weight-height) were identified and randomly assigned to consume for 5 days/week for 3.5 months a snack prepared with QPM or conventional maize. QPM positively influenced children's growth: weight (0.80 vs. 0.19 kg gained from baseline to endline between the QPM and conventional maize groups, respectively), height (2.02 vs. 1.23 cm in QPM vs. conventional) and Z score for weight-age (0.17 vs. -0.26 Z in QPM vs. conventional) and height-age (0.06 vs. -0.23 Z in QPM vs. conventional). When other factors that could affect growth with respect to weight, height, weight-age Z score and height-age Z score were controlled for, the intervention group (QPM > conventional) was a statistically important factor (P < 0.01). The QPM snack, however, had no effect on the incidence of diarrheal episodes or respiratory infections. In conclusion, QPM improves the nutritional status of pre-school children who are mild or moderately malnourished but has no effect on the incidence of diarrheal episodes or respiratory infections.

Mycotoxicological quality evaluation of corn samples used by processing industries in the Northern region of Paraná State, Brazil.

Based on fungal and fumonisin contamination of 870 freshly harvested samples, the quality of corn used by processing industries in the Northern region of Parana State, Brazil (2003 and 2004 crop-year) was evaluated. Sampling was carried out for each crop at two points in the production chain, i.e. at reception by the processors and at the pre-drying step. Corn samples were more frequently contaminated with Fusarium sp. (100%) and Penicillium sp. (84.1-95.3%) than Aspergillus sp. (5.6-19.8%). Fumonisin B(1) (FB(1)) was detected in all samples from the two points in both crop-years. FB(1) levels ranged 0.02-11.83 microg g(-1) in the reception and 0.02-10.98 microg g(-1) in the pre-drying samples of the 2003 crop. Samples from the 2004 crop showed FB(1) levels ranging 0.03-12.04 microg g(-1) in the reception and 0.06-7.74 microg g(-1) in the pre-drying samples. FB(2) levels ranged 0.02-5.25 microg g(-1) in the reception and 0.01-7.89 microg g(-1) in the pre-drying samples (2003 crop-year). In samples from the 2004 crop, FB(2) levels ranged 0.02-6.12 microg g(-1) in the reception and 0.05-3.47 microg g(-1) in the pre-drying samples. Low fumonisin levels were detected in most corn samples used by processors in the Northern region of Parana State, showing a decreasing trend in fumonisin contamination over the years.

Relationship between structural and biochemical characteristics and texture of corn grains

The texture of corn grains is a fundamental characteristic for the industry as well as for grain producers and processors. To further understand the mechanisms involved in grain hardness, contrasting corn cultivars for grain hardness and protein quality were evaluated. The cultivars were Cateto L237/67 (hard endosperm and low protein value), QPM BR 451 (semi-hard endosperm and high protein value); Bolivia-2 (floury endosperm and low protein value), and Opaque-2 (floury endosperm and high protein value). Evaluations were carried out at 10, 20, 30, 40, 50, and 60 days after pollination in developing corn grains and in the mature grain. In developing grains, evaluation consisted in the determination of the area, percentage of starch granules, distribution of starch granules, and protein bodies in the endosperm. In mature corn grains, the parameters evaluated were: density, percentage of total proteins, levels of lysine and tryptophan, and banding pattern of zeins. The results indicate that the higher physical resistance of corn grains from the cultivars analyzed is influenced by the high percentage of total proteins, high synthesis of 27-kDa zeins, presence of protein bodies, and perfect organization of starch granules in the endosperm, independent of their sizes.

Effects of extraction conditions on improving the yield and quality of an anthocyanin-rich purple corn (Zea mays L.) color extract.

Purple corn (Zea mays L.) is a rich and economic source of anthocyanin colorants and functional ingredients. However, high levels of anthocyanin-rich waste are generated during processing, reducing the yields and increasing the costs of the final product. This waste has been associated with anthocyanin complexation with tannins and proteins. Our objective was to evaluate anthocyanin extraction methods to reduce purple corn waste. Different solvents (water, 0.01%-HCl-acidified water, and 0.01%-HCl-acidified ethanol), temperatures (room temperature, 50, 75, and 100 degrees C), and times of exposure to the solvents were investigated. Acetone (70% acetone in water) extraction was used as control. Anthocyanins, total phenolics, tannins, and proteins in extracts were measured by the pH differential, Folin-Ciocalteu, protein precipitation, and BCA assay methods. Qualitative analyses were done by HPLC coupled to a PDA detector and SDS-PAGE analysis. Water at 50 degrees C achieved the highest yield of anthocyanins (0.94 +/- 0.03 g per 100 g dry corncob) with relatively low tannins and proteins, comparable to the anthocyanin yield obtained by 70% acetone (0.98 +/- 0.08 g per 100 g dry corncob). Extending the extraction time from 20 to 60 min and using consecutive reextraction procedures reduced anthocyanin purity, increasing the yields of other phenolics. A neutral protease was applied to the extracts and effectively decomposed the major protein that was believed to contribute to the development of anthocyanin complexation and waste generation. Extraction time, consecutive reextraction procedures, and enzyme hydrolysis should be considered for high yield of anthocyanins and waste reduction.