Efeito do processamento na atividade antioxidante do grão de amaranto (Amaranthus cruentus L. BRS-Alegria)

As características nutricionais, funcionais e agrícolas do amaranto são responsáveis pelo aumento do interesse por este alimento nas últimas décadas. O grão pode ser cozido, estourado, torrado, extrusado ou moído para ser consumido. Foi avaliado o efeito destes processamentos na atividade antioxidante do grão de amaranto, através das determinações do teor de fenólicos totais e da atividade antioxidante in vitro por dois métodos: inibição da oxidação lipídica pelo sistema \03B2-caroteno/ácido linoléico e índice de atividade antioxidante pelo aparelho Rancimat®. Os processamentos reduziram em média o teor de fenólicos totais do grão de amaranto de 31,7 para 22,0 mg de equivalentes de ácido gálico/g de resíduo seco. Observou-se que o extrato obtido por etanol do grão torrado foi o único a apresentar menor índice de atividade antioxidante (IAA) em relação ao grão cru (1,3 v 1,7). Os processos de extrusão, torração e explosão não alteraram a capacidade de inibição da oxidação lipídica (IOL) do amaranto (55 por cento). Já o cozimento aumentou o IOL (79 por cento), o que pode ter ocorrido devido ao maior tempo de processamento sob alta temperatura (100ºC/10min). Os métodos mais comuns de processamento do grão de amaranto ocasionaram redução do teor de fenólicos totais, no entanto a atividade antioxidante do estourado e do extrusado, avaliada pelos dois métodos, foi semelhante ao do grão cru. O grão de amaranto tanto cru como processado apresenta potencial antioxidante. Polifenóis, antocianinas, flavonóides, tocoferóis, vitamina C e compostos gerados na reação de Maillard podem estar relacionados à atividade antioxidante deste grão

Potential of Amaranthus cruentus BRS Alegria in the production of flour, starch and protein concentrate: chemical, thermal and rheological characterization

BACKGROUND: Amaranth is a little-known culture in Brazilian agriculture. Amaranthus cruentus BRS Alegria was the first cultivar recommended by Embrapa for the soil of the Brazilian scrubland. In order to evaluate the potential of this species in the production of flour, starch and protein concentrates, the latter products were obtained from A. cruentus BRS Alegria seeds, characterized and compared with the products obtained from the A. caudatus species cultivated in its soil of origin. RESULTS: The seeds of A. cruentus BRS Alegria furnished high-purity starch and flour with significant content of starch, proteins, and lipids. The starch and flour of this species presented higher gelatinization temperatures and formed stronger gels upon cooling compared with those obtained from the A. caudatus species. This is due to their greater amylose content and a difference in the composition of the more important fatty acids, such as stearic, oleic and linoleic acids, which indicates that they have greater heat stability. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and differential scanning calorimetry revealed the presence of albumins, globulins, glutelins and prolamins in the protein concentrate, which was obtained as a byproduct of starch production. CONCLUSION: Amaranthus cruentus BRS Alegria has potential application in the production of flour, starch and protein concentrates, with interesting characteristics for use as food ingredients. (C) 2010 Society of Chemical Industry

Comparison of properties of native and extruded amaranth (Amaranthus cruentus L. - BRS Alegria) flour

The aim of this study was to compare some of the properties of native and extruded amaranth flour obtained under mild and severe extrusion conditions. The chemical composition of the flours was similar. Flours obtained by both extrusion processes presented high solubility in water, low values of L* (luminosity) and an absence of endothermic peak on the DSC method. Water absorption, retrogradation tendency, final viscosity and the viscous behavior by rheology analysis were also studied. The results indicate that extruded flours have a good potential as an ingredient for food exposed to heat treatment at a high temperature and mechanical shear, for use in instant meal products. On the other hand, original flour properties are comparable to those of amaranth starch, which exhibits similarly high quality paste stability, low solubility in water, and elastic behavior, and could be used as a substitute for raw flour in a range of food formulas. (C) 2011 Elsevier Ltd. All rights reserved.

Storage effect on the acceptability of snacks made of pure amaranth and blends of amaranth and corn or chickpea

Snacks made by extrusion cooking of pure amaranth flour or mixtures of 80 per cent amaranth flour and 20 per centcorn grits or chickpea flour were developed to replace the traditional commercial ones with improved nutritional and functional quality. Pure amaranth snacks and the blended ones were flavored with salty and sweet flavors and evaluated for acceptability using a 9-point hedonic scale. The good acceptance observed for either salty or sweet flavored snacks indicated that they have characteristics to compete with similar commercial products. Acceptability of salty snacks increased with storage time at room temperature in BOPP (polypropylene bi-guided) packs whereas slightly decreased for the sweet ones. This type of storage proved to be very efficient for the conservation of the salty product and also suitable for the sweet ones

Effect of glutamate and inosinate on sensory and instrumental texture of extruded products

Expanded products have been developed by extrusion of non-conventional highly nutritious raw materials such as amaranth and chickpea blended with bovine lung. As sensory acceptance of these snacks is restricted, this study aimed at improving their texture, through the addition of monosodium glutamate (MSG) and disodium inosinate (IMP) flavor enhancers to the feeding material, or to the flavor added after the extrusion. Sensory and mechanical analyses showed that both enhancers affected texture, assessed by sensory and instrumental methods. Addition of IMP together with MSG to the chickpea-based snacks presented the best results. This beneficial effect was not observed in the amaranth-based snack, suggesting that IMP and MSG can favorably impact texture of extruded products depending on the amount and type of protein present

Amaranth bars enriched with fructans: acceptability and nutritional value

Amaranth bars enriched with fructans: acceptability and nutritional value. There is an increasing appeal for convenience foods with potential health benefits to the consumer. Raw materials with high nutritional value and functional properties must be used on the development of these food products. Amaranth is a gluten-free grain with high nutrition value. Inulin and oligofructose are prebiotic ingredients presenting effects as the enhancement of calcium absorption. Amaranth bars enriched with inulin and oligofructose were developed in the flavors: banana, Brazilian nuts and dried grape, coconut, peach, strawberry and wall nut. The proximate composition were determined and compared to commercial cereal bars, available in traditional (n=59), light (n=60), diet (n=8), with soy (n=10) and quinoa (n=1) categories. Amaranth bars present mean global acceptance values from 6.3 to 7.6 on a 9-point hedonic scale, nutritional advantages as compared to commercial cereal bars (caloric reduction and higher levels of dietary fiber). Although amaranth is an unknown raw material in Brazil, it shows good potential to be used in the manufacturing of ready-to-eat products. As they are gluten free, these amaranth bars are also an alternative product for celiacs, also contributing to the enhancement of calcium absorption, a problem frequently observed in these patients.

Effects of processing methods on amaranth starch digestibility and predicted glycemic index

Amaranth has attracted a great deal of interest in recent decades due to its valuable nutritional, functional, and agricultural characteristics. Amaranth seeds can be cooked, popped, roasted, flaked, or extruded for consumption. This study compared the in vitro starch digestibility of processed amaranth seeds to that of white bread. Raw seeds yielded rapidly digestible starch content (RDS) of 30.7% db and predicted glycemic index (pGI) of 87.2, the lowest among the studied products. Cooked, extruded, and popped amaranth seeds had starch digestibility similar to that of white bread (92.4, 91.2, and 101.3, respectively), while flaked and roasted seeds generated a slightly increased glycemic response (106.0 and 105.8, respectively). Cooking and extrusion did not alter the RDS contents of the seeds. No significant differences were observed among popped, flaked, and roasted RDS contents (38.0%,46.3%, and 42.9%, respectively), which were all lower than RDS content of bread (51.1%). Amaranth seed is a high glycemic food most likely because of its small starch granule size, low resistant starch content (< 1%), and tendency to completely lose its crystalline and granular starch structure during those heat treatments.

Effect of processing on the antioxidant activity of amaranth grain

Effect of processing on the antioxidant activity of amaranth grain. Amaranth has attracted increasing interest over recent decades because of its nutritional, functional and agricultural characteristics. Amaranth grain can be cooked, popped, toasted, extruded or milled for consumption. This study investigated the effect of these processes on the antioxidant activity of amaranth grain. Total phenolic content and in vitro antioxidant activity were determined according to two methods: inhibition, of lipid oxidation using the beta-carotene/linoleic acid system and the antioxidant activity index using the Rancimat (R) apparatus. The processing reduced the mean total phenolics content in amaranth grain from 31.7 to 22.0 mg of gallic acid equivalent/g of dry residue. It was observed that the ethanol extract from toasted grain was the only one that presented a lower antioxidant activity index compared with the raw grain (1.3 versus 1.7). The extrusion, toasting and popping processes did not change the capacity to inhibit amaranth lipid oxidation (55%). However, cooking increased the inhibition of lipid oxidation (79%), perhaps because of the longer time at high temperatures in this process (100 degrees C/10 min). The most common methods for processing amaranth grain caused reductions in the total phenolics content, although the antioxidant activity of popped and extruded grain, evaluated by the two methods, was similar to that of the raw grain. Both raw and processed amaranth grain presents antioxidant potential. Polyphenols, anthocyanins, flavonoids, tocopherols, vitamin C levels and Maillard reaction products may be related to the antioxidant activity of this grain.