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.

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.

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.

[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.

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.

Understanding the potential impact of transgenic crops in traditional agriculture: maize farmers' perspectives in Cuba, Guatemala and Mexico.

Genetically engineered transgenic crop varieties (TGVs) have spread rapidly in the last 10 years, increasingly to traditionally-based agricultural systems (TBAS) of the Third World both as seed and food. Proponents claim they are key to reducing hunger and negative environmental impacts of agriculture. Opponents claim they will have the opposite effect. The risk management process (RMP) is the primary way in which TGVs are regulated in the US (and many other industrial countries), and proponents claim that the findings of that process in the US and its regulatory consequences should be extended to TBAS. However, TBAS differ in important ways from industrial agriculture, so TGVs could have different effects in TBAS, and farmers there may evaluate risks and benefits differently. To evaluate some potential impacts of TGVs in TBAS we used the RMP as a framework for the case of Bt maize in Mesoamerica and Cuba. We interviewed 334 farmers in Cuba, Guatemala and Mexico about farming practices, evaluations of potential harm via hypothetical scenarios, and ranking of maize types. Results suggest high potential for transgene flow via seed, grain and pollen; differences in effects of this exposure in TBAS compared with industrial agriculture; farmers see some potential consequences as harmful. Perceptions of harm differ among farmers in ways determined by their farming systems, and are different from those commonly assumed in industrial systems. An RMP including participation of farmers and characteristics of TBAS critical for their functioning is necessary to ensure that investments in agricultural technologies will improve, not compromise these agricultural systems.

Effects of soybean fortification on protein quality of tortilla-based diets produced from regular and quality protein maize.

The physiological development of laboratory rats fed with a typical indigenous tortilla diet was studied for two generations. The experiment compared casein control diet and five different types of diets: (1) a diet of tortillas obtained from fresh masa (FM); (2) regular tortillas produced from enriched dry masa flour containing vitamins B1, B2, niacin, folic acid, and the microminerals iron and zinc (REDMF); (3) tortillas produced from enriched dry masa flour fortified with 6% defatted soybean meal (FEDMF); (4) tortillas produced from enriched quality protein maize flour (EQPM); and (5) and, tortillas produced from enriched quality protein maize flour fortified with 3% defatted soybean meal (FEQPM). The growth of rats fed FEDMF and FEQPM diets was significantly higher (P < 0.05) in both generations than their counterparts fed EQPM, REDMF, or FM diet. Animals fed quality protein maize (QPM) tortilla had the highest protein digestibility, but the FEQPM and FEDMF diets had the highest biological value (BV), net protein utilization (NPU), and protein-digestibility-corrected EAA scores (PDCEAAS). The difference among treatments was more evident in the second-generation rats. The pregnancy rate, number of newborns/litter, litter weight, and newborn survival rate was also higher for rats fed FEDMF, EQPM, and FEQPM diets than their counterparts fed REDMF and FM.

Nutrition disorders and immunologic parameters: study of the thymus in growing rats.

OBJECTIVES: We studied the effect of a low-quality dietary protein on cellular proliferation and maturation in the thymus of growing rats over time. METHODS: After weaning Wistar rats were fed a diet containing 6.5 g/100 g of corn flour for 6, 10, 18, and 45 d (M groups). For comparison, other rats were fed a diet containing 6.5 g/100 g of casein (Cas groups), and well-nourished age-matched control rats were fed a commercial laboratory diet (C groups). Food intake, body weight, thymus weight, total number of thymocytes, and the percentages of CD43(+) and Thy1(+) thymocyte phenotypic antigen determinants were measured. RESULTS: M versus Cas and C groups showed significant differences (P < 0.01) in body and thymus weights after 6 d of feeding, and the total number of thymocytes and the percentages of CD43(+) and Thy1(+) were significantly lower after 10 d of feeding. The results indicated that consuming a cereal diet for short or long periods causes thymus atrophy in growing rats, with significant reductions in the total number of T-cells concomitant with increases in the number of immature thymocytes. CONCLUSIONS: The data showed that, in addition to low-protein concentration, low-quality dietary protein is a limiting factor in certain steps of cellular intrathymic pathways, probably related to the requirement of specific amino acids for optimal immune response.

[Nixtamalization cooking characteristics of 11 maize varieties]. / Características de cocción por nixtamalización de once variedades de maíz.

In the present study, 11 maize varieties were analyzed for their nixtamalization cooking quality. The 11 varieties were grown in the same locality and in the same year. The samples were evaluated for their physical characteristics, such as moisture content averaging 13.3%, average 1000 kernel weight (312.5 g), grain hardness through density (1.28 g/ml) and percent floaters (9.5%). These data indicated that all maize varieties had a hard endosperm which is recommended for the nixtamalization cooking process. The 11 varieties were formed on the average by 5.7% seed coat, 11.5% germ and 82.8% endosperm. The low seed coat content suggest a low solids loss during processing. Cooking quality evaluation was done by applying a standard lime cooking procedure to all varieties. An average solid loss of 3.2% was measured, with 0.8% of seed coat still attached to the endosperm. Water absorption at the end of cooking was 40.8% without soaking and 46.9% at the end of soaking. Nixtamal moisture was 47.9% after soaking and only 41.5% at the end of cooking. Cooking time with soaking for 50% moisture in the grain varied from 69 to 122 minutes at 1500 meters over sea level. The cooked grain was dried with hot air and ground however, the particle size obtained was not as that in commercial nixtamalized maize flour. However, the cooking quality parameters to make dough and tortillas were acceptable, with a penetration index of hydrated flour of 178.6 mm, pH 7.97, water absorption index (WAI) of 3.23 g gel/g flour and 4.11% water solubility index (WSI). All flours from the 11 varieties of maize gave acceptable tortillas as evaluated by physical characteristics and sensory quality. However of the 11 varieties 7 including the control were superior for nixtamalization cooking quality.

Fortifación de harina de maíz con hierro a nivel artesanal de una comunidad andina del Ecuador, 1998 / Fortifación of flour of corn with iron at handmade level of an andean community of the Ecuador, 1998

Diferentes estrategias se han desarrollado para hacer frente a la anemia por deficencia de hierro (MSP, 1995; Bowley, 1997; Lofti y col., 1996; Sunny y Freire, 1997; INACG,1990). En el país, a finales del primer trimestre de 1998, el Ministerio de Salud Pública del Ecuador puso en ejecución el Programa Nacional de Fortificación de la harina de trigo con hierro y vitaminas que beneficiaría al sector de la población consumidor de este alimento (MSP, 1998). Sin embargo, una apreciable parte de los ecuatorianos son consumidores de harina de maíz, por lo que posiblemente estén marginados de estos beneficios, especialemnte las comunidades andinas productoras de este cereal, como es el caso de San José de Minas, en donde se cultiva y elbora localmente la harina de maís, qu a su vez constituye el alimento básico de las familias

Influence of dietary forage level and forage coarseness of grind on growth performance and digestive function in feedlot steers.

We conducted two trials to examine the influence of dietary forage level (FL; 16 and 8% sudangrass hay) and forage coarseness of grind (COG; ground to pass through a 2.5- vs 7.6-cm diameter screen) on growth performance and digestive function in feedlot steers fed a steam-flaked corn-based finishing diet. Thirty-two Mexican crossbred steers (297 kg) were used to determine treatment effects on growth performance during an 80-d finishing period. There were no treatment interactions (P > .10). Reducing FL increased (17%, P < .05) ADG. decreased (23%, P < .01) feed/gain, and increased (17% and 22%, P < .01) dietary NEm and NEg. Coarseness of grind did not affect (P > .10) steer performance. Treatment effects on digestive function were evaluated using four Holstein steers with cannulas in the rumen and proximal duodenum. There were no treatment interactions (P > .10) on nutrient digestibility. Forage level did not affect (P > .10) ruminal digestion of OM, N, or microbial efficiency. However, decreasing FL increased (P < .05) total tract digestion of OM (5.0%), N (5.7%), and ME (8.7%). Increasing COG increased total tract digestibility of OM (2.3%, P < .01), ADF (24.4%, P < .01); N (3.8%, P < .01), and ME (3.7%, P < .05). Increasing FL increased (P < .10) ruminal pH and decreased (P < .10) ruminal molar proportions of butyrate. Increasing COG did not influence (P > .10) ruminal pH or ruminal VFA molar proportions. We conclude that increasing coarseness of ground sudangrass may not improve the performance of feedlot steers when the forage is fed at either 8 or 16% of diet DM, although measures of ruminal and total tract nutrient digestibility may be slightly increased.

Influence of flake density on the feeding value of steam-processed corn in diets for lactating cows.

Four primiparous Holstein cows (112 d in lactation) with cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square design. Dry-rolled (DR) corn (density .52 kg/L) was compared with stream-flaked (SF) corn processed to three flake densities: .39, .32, and .26 kg/L. The basal diet contained (DM basis) 43.4% alfalfa hay, 39.5% corn (DR or SF), 2.2% yellow grease, 9.6% cane molasses, .7% sodium bicarbonate, and 4.6% protein-mineral supplement. Steam flaking increased DM intake (P < .01). There were no treatment effects on ruminal pH (P > .10). Ruminal molar ratios of acetate and propionate were lower (P < .01) for SF than for DR corn and declined (linear component, P < .01) as flake density decreased. Ruminal digestibility of OM was not affected (P > .10) by corn processing. Ruminal starch digestibility increased (linear component, P < .05) as flake density decreased. Ruminal ADF digestibility was decreased by SF (P < .01); this effect was exacerbated by degree of processing (linear component, P < .05). Ruminal N efficiency (duodenal nonammonia N/N intake) was greater (P < .10) for SF than for DR corn because of an improved (P < .10) microbial efficiency. Steam flaking at all densities increased postruminal digestibility of OM (42.4%, P < .01), starch (84.9%, P < .01) N (13.6%, P < .01), and lipid (11.8%, P < .05). Total-tract digestibilities of OM, N, starch, DE and ME were greater (15.2, 11.5, 25.2, 14.9, and 20.0%, respectively, P < .01) for SF (mean of the three densities) than for DR corn. Total-tract digestibility of starch increased (linear component, P < .10) with degree of processing. However, this effect was offset by decreased (linear and quadratic components, P < .05) ADF digestibility. Steam flaking improved the feeding value of corn for lactating cows by improving diet acceptability and digestibility of lipid, starch, and N. Steam flaking increased the estimated NEl of corn by 33%. Optimal flake density probably is between .32 and .39 kg/L.

Comparación de métodos para medir la dureza del maíz (Zea mays L.) / Comparison of methods for determining corn hardness (Zea mays L.)

La dureza del maíz es una propiedad intríseca importante del grano. En la actualidad existe controversia acerca de cuál métodos es el más adecuado para evaluar ese grado de dureza, por lo que en el presente trabajo se compararon algunos métodos para medición de dureza, con la finalidad de identificar el más apropiado. Se empleó, para el caso, una población de maíz con un rango de dureza de suave a duro. Los métodos sometidos a prueba fueron: textura de endospermo (TE), índice de perlado (IP), índice de flotación (IF), densidad (D), reflectancia en el infrarojo (NIR), peso hectolítrico (Ph) y tiempo de molienda en el durómetro Brabender (TDB). El métodos del IF resultó ser el más adecuado para determinar la dureza del grano de maíz; además de presentar bajos coeficientes de variación, permitió establecer una buena diferenciación entre los maíces de endospermo suave, intermedio y duro. El TDB y NIR no se encontraron adecuados para estimar la dureza del grano debido a que acusaron alta variabilidad en los resultados. El Ph y D mostraron dificultad para diferenciar entre maíces de endospermo intermedio y suave