STARCH CHARACTERIZATION OF DIFFERENT BLUE MAIZE VARIETIES.

http://onlinelibrary.wiley.com/doi/10.1002/star.201000023/abstrac

ISOLATION AND CHARACTERIZATION OF MEXICAN CHAYOTE TUBER (SECHIUM EDULE SW.) STARCH.

http://onlinelibrary.wiley.com/doi/10.1002/star.201000078/abstrac

PHYSICAL AND CHEMICAL CHARACTERISTICS OF BLUE CORN FROM TWO RACES: STARCH MORPHOLOGY.

http://www.inifap.gob.mx/SitePages/revistas/rmca.asp

Características físicas y químicas de dos razas de maíz azul: morfología del almidón

There are areas in Mexico, where local varieties of blue corn are grown (Zea mays L.), which have variability in size, density and grain hardness as well as chemical composition. Although these variables are defined by genetic factors, they also depend on farming practices, climatic conditions and soil type. The physical characteristics of corn grain are related to production and yield aspects, while its chemical composition and starch granules morphology, help to define the nutritional quality and its use in food processing. The objective of this study was to determine the physical and chemical properties of blue corn grain from two races and morphologically characterize the starch granules of the endosperm. The study was conducted at the Centre for Development of Biotic Products of the National Polytechnic Institute and the Valley of Mexico Experimental Station of the National Forestry, Agriculture and Livestock Research Institute. The samples were collected in the field with the producers, six Tabloncillo race materials at locations in Sinaloa and nine from Chalqueño race at Tlaxcala and Mexico State locations. Tabloncillo corn has small grains, higher hardness and damaged starch, and lowest levels of anthocyanins than Chalqueño corn has. The starch amount in both races was from 0.78 to 0.89 g g-1 of dry sample, and they are classified as normal because of their amylose content. The starch granules were spherical with smooth surface and a bimodal distribution (small granules were 2-8 ¿m and large granules were 16-18 um). The main differences between the two races were their grain size, floating rate and anthocyanin content.En México existen regiones donde se cultivan variedades criollas de maí­z azul (Zea mays L.), que poseen variabilidad de tamaño, densidad y dureza del grano, así­ como composición quí­mica. Estas variables si bien están definidas por el factor genético, también dependen de las prácticas de cultivo, condiciones climáticas y tipo de suelo. Las caracterí­sticas fí­sicas del grano de maí­z tienen relación con aspectos de producción y rendimiento, mientras que su composición quí­mica y la morfologí­a de los gránulos de almidón, ayudan a definir la calidad nutritiva y su uso en la elaboración de alimentos. El objetivo del trabajo fue determinar las propiedades fí­sicas y quí­micas del grano maí­z azul proveniente de dos razas, y caracterizar morfológicamente los gránulos del almidón de su endospermo. El trabajo se realizó en el Centro de Desarrollo de Productos Bióticos del Instituto Politécnico Nacional y en el Campo Experimental Valle de México del Instituto Nacional de Investigaciones Forestales Agrí­colas y Pecuarias. Las muestras fueron colectadas en campo con los productores, seis materiales de la raza Tabloncillo en localidades de Sinaloa y nueve de la raza Chalqueño en localidades de Tlaxcala y Estado de México. Los maí­ces de la raza Tabloncillo presentaron granos pequeños, mayor dureza y cantidad de almidón dañado, y menores contenidos de antocianinas, que la raza Chalqueño. La cantidad de almidón de ambas razas fue de 0.78-0.89 g g-1 de muestra seca, y por su contenido de amilosa se clasifican como almidones normales. Las formas de los gránulos de almidón fueron esféricas con superficie lisa y una distribución bimodal (gránulos pequeños 2-8 μm y grandes 16-18 μm). Las diferencias principales entre las dos razas fueron su tamaño de grano, í­ndice de flotación y contenido de antocianinas

Starch digestibility: past, present and future

In the last century, starch present in foods was considered to be completely digested. However, during the 1980s, studies on starch digestion started to show that besides digestible starch, which could be rapidly ors lowly hydrolysed, there was a variable fraction that resisted hydrolysis by digestive enzymes. That fraction was named resistant starch (RS )and it encompasses those forms of starch that are not accessible to human digestive enzymes but can be fermented by the colonic microbiota, producing short-chain fatty acids. RS has been classified into five types, depending on the mechanism governing its resistance to enzymatic hydrolysis. Early research on RS was focused on the methods to determine its content in foods and its physiological effects, including fermentability in the large intestine. Later on, due to the interest of the food industry, methods to increase the RS content of isolated starches were developed. Nowadays, the influence of RS on the gut microbiota is a relevant research topic owing to its potential health-related benefits. This review summarizes over 30 years of investigation on starch digestibility, its relationship with human health, the methods to produce RS and its impact on the microbiome

Functional study of raw and cooked blue maize flour : Starch digestibility, total phenolic content and antioxidant activity

The purpose of this study was to determine the chemical composition and antioxidant capacity of blue maize (BM) (Zea mays L.) flour and to investigate the effects of polyphenol-containing extracts and BM wholegrain flour on starch digestion under uncooked and cooked conditions; commercial white maize flour was used as control. Total phenolic content in BM flour (BMF) (164 ± 14 mg gallic acid/g of dry matter) was higher than white maize (127 ± 7 mg gallic acid/g of dry matter), and the presence of anthocyanins (2.0 ± 0.5 mg cyanidin 3-glucoside/100 g) was detected. Also, an important scavenging activity against ABTS (2,2’-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and ferric reducing power (FRAP) was determined. Extracts of BMF reduced amylase activity (>90% of inhibition). BMF showed higher slowly digestible and resistant starch contents, thus exhibiting lower predicted glycemic index than white maize. Total anthocyanins (r = −0.89 and r = −0.79, p<0.05), antioxidant capacity (r = −0.86 and r = −0.96, p<0.05), total starch (r = 0.99 and 0.92, p<0.05) and resistant starch content (r = −0.99 and r = −0.92, p<0.05) were correlated with pGI for uncooked and cooked flours, respectively. These results indicate the potential use of BMF and its phenolic-rich extract as functional ingredients to develop antioxidant and indigestible carbohydrate-rich foods with potential health benefits

Dietary fiber content, texture, and in vitro starch digestibility of different white bread crusts

Different types of white bread are sold and widely consumed worldwide. The objective of this study was to evaluate the starch digestibility in the crust of different white breads. Three popular commercial white breads were analyzed for dietary fiber (DF), thermal properties, texture, starch hydrolysis and resistant starch (RS) contents, in freshly baked and stored samples. The DF content in fresh crusts “as eaten” (6.8–7.2%) represents about 25% of the recommended daily consumption. The hardness and elasticity, RS and DF contents increased upon storage, associated with incomplete starch gelatinization and retrogradation, corroborated by the thermal analysis. The hydrolysis rate suggested that the structural arrangement of the starch components in the crust, possibly due to the low water content resulting from evaporation during baking and upon storage, restricts the susceptibility to digestive enzymes action. Consumption of bread crust may be suggested as a means to increase the DF intake