Rolando J. González

Mycotoxins inactivation by extrusion cooking of corn flour

Aims: To evaluate the effects of the extrusion cooking process on the inactivation of mycotoxins in corn flour.

Effect of extrusion conditions on physicochemical and sensorial properties of corn-broad beans (Vicia faba) spaghetti type pasta.

Corn-broad bean spaghetti type pasta was made with a corn/broad bean flour blend in a 70:30 ratio, through an extrusion-cooking process (Brabender 10 DN single-screw extruder with a 3:1 compression ratio). The effect of temperature (T=80, 90 and 100°C) and moisture (M=28%, 31% and 34%) on the extrusion responses (specific consumption of mechanical energy and pressure) and the quality of this pasta-like product (expansion, cooking-related losses, water absorption, firmness and stickiness) was assessed. The structural changes of starch were studied by means of DSC and XRD. The extrusion-cooking process, at M=28% and T=100°C, is appropriate to obtain corn-broad bean spaghetti-type pasta with high protein and dietary fibre content and adequate quality. The cooking characteristics and resistance to overcooking depended on the degree of gelatinisation and formation of amylose-lipid complexes. The critical gelatinisation point was 46.55%; beyond that point, the quality of the product declines.

Development of naturally activated edible films with antioxidant properties prepared from red seaweed Porphyra columbina biopolymers.

The aim of this work was to study the physicochemical and antioxidant properties of phycobiliproteins-phycocolloids-based films, obtained from mixtures of two aqueous fractions extracted from Porphyra columbina red seaweed, one enriched in phycocolloids (PcF) and the other in phycobiliproteins (PF). Films with different ratios of PF:PcF (0, 25, 50, 75, 100% [w/w]) and without plasticizer addition were prepared by casting. PcF films had excellent mechanical properties (tensile strength ∼50MPa, elongation at break ∼3% and an elastic modulus ∼17.5MPa). The addition of PF to formulations exerted a plasticizing effect on the PcF matrix, which was manifested in moisture content, water solubility and mechanical properties of the resulting films but not in its water vapour permeability. The antioxidant capacity (TEAC) of the PcF films was significantly increased by the addition of PF and a direct relationship between TEAC and the total phenolic compounds (r(2)=0.9998) and R-phycoerythrin (r(2)=0.9942) was observed.

Chemical composition, nutritional and antioxidant properties of the red edible seaweed Porphyra columbina

Abstract Proximate composition, fatty acids and amino acid profiles and nutritional (chemical score, protein digestibility, PDCAAS and mineral dialyzability) and antioxidant properties (TEAC, DPPH and power reduction) from Porphyra columbina were evaluated. Total dietary fiber (48.02 ± 1.13 g/100 g dry weight) and protein (24.61 ± 0.21 g/100 g dry weight) were the two most abundant components in this seaweed. The main saturated and unsaturated fatty acids were C16:0 and C20:5 (n−3), respectively. The limiting amino acid was tryptophan with a chemical score of 57%. Protein digestibility was 74.33 ± 3.0%. Porphyra columbina has high mineral content with good Na/K relationship and medium value of potential mineral accessibility (P, Ca and Zn dializability: 18.75 ± 0.01, 17.62 ± 0.16 and 16.70 ± 0.44, respectively). The highest antioxidant properties were obtained with an acetone/water extraction system. This work provides important information about chemical composition and nutraceutical new properties of P. columbina.

Effects of extrusion conditions on physical and nutritional properties of extruded whole grain red sorghum (sorghum spp)

Abstract In order to analyze the effects of extrusion temperature (T: 164, 182, 200 °C) and grits moisture content (g/100 g sample) (%M: 14, 16.5, 19) on textural and physicochemical properties of red sorghum extrudates, whole grain flour was extruded according to a factorial experimental design. The higher values for specific mechanical energy consumption (1006.98 J/g) and expansion (3.36) were obtained at 164 °C–14%M and for sensorial hardness at 164 °C–19%M. While for specific volume, the highest value (10.41 cm3/g) was obtained at 200 °C–14%M. Water solubility and water absorption were directly related with T and inversely with M. Microscopic observation of the samples indicates that the greatest cooking degree was obtained at 200 °C–4%M and the lowest at 164 °C–19%M. Extrusion at 182 °C–14%M allows obtaining an expanded product with good properties. Proximal composition did not show statistically significant differences with raw sample. Extruded sample showed a 25.4% reduction of available lysine and a 31% increase in protein digestibility.

Physico-chemical and cooking characteristics of some rice varieties

Some physicochemical and cooking characteristics corresponding to different varieties and commercial samples of rice were analysed. Some mechanical properties determined by both, the viscoelastograf and the Instrom Universal Food Testing Machine were also analysed. Gelatinization time (Gt), gelatinization endotherm and amylose content were determined. The results showed that there was a very good correlation between gelatinization temperature and Gt, while no noticeable correlation among others phsycochemical characteristics was observed. Regarding the mechanical properties, both methods permited to show significant differences among most of the samples. However, when the samples order obtained with hardness (Instrom) values was compared with that corresponding to firmness (Viscoelastograf) values, some discrepancies were observed. This could be attributable to the number of grains and the cooking time used in each method. There was good linear correlation between hardness and amylose content. On the contrary, none of the viscoelastograf parameters are correlated well with amylose. An interesting point was that the slope of the regression line obtained between firmness and cooking time could be utilised as a measure of cooking resistance of each sample and was related to the rate of water absorption.

ELABORACIÓN DE PAN SIN GLUTEN CON HARINAS DE ARROZ EXTRUDIDAS ELABORATION OF BREAD WITHOUT GLUTEN FROM EXTRUDED RICE FLOURS

Abstract The technological behavior of extruded rice flours from seven genotypes, using a baking test to elaborate bread without gluten, was studied comparing them with the performance of the same samples without extrusion treatment. Rice flours were extruded using two levels of hydration: 15 and 30%. Baking tests were carried out with such hydration levels to obtain, in different mixtures, the same consistency before baking. Bread quality was evaluated by assessing sensory attributes using a trained panel. When no-waxy rice flour was 100% replaced in the recipe by the same flour but extruded with 15% moisture, bread volume was improved 22% and crumb structure quality 120%. Nevertheless, when rice flours of waxy genotypes, extruded at moisture level of 15% or 30% were used in the formulation, volume improved 41% and crumb structure 142%. These waxy genotypes are then especially suitable for making bread without gluten. Resumen Se estudió el comportamiento, en la elaboración de pan sin gluten, de siete genotipos de arroz cuyas harinas fueron tratadas por extrusión y se comparó con las mismas harinas sin extrudir. Las harinas de arroz fueron extrudidas en laboratorio con dos niveles de humedad: 15 y 30%. La panificación se llevó a cabo con la hidratación necesaria para mantener la mezcla batida a consistencia constante. Los panes fueron evaluados por sus atributos sensoriales a través de un panel entrenado. Cuando en la formulación se reemplazó totalmente la harina de arroz no-waxy sin extrudir por la misma harina extrudida con 15% de humedad, mejoró el volumen del pan en un 22% y la estructura de la miga en un 120%. A su vez, cuando se reemplazó con harinas de genotipos waxy extrudidas tanto a 15% como a 30% de humedad estos atributos de calidad fueron significativamente mejores, creciendo el volumen en un 41% y la estructura de la miga en un 142%. Por lo tanto, estos genotipos waxy con tratamiento por extrusión resultan especialmente aptos para la elaboración de pan sin gluten. Palabras clave: Panificación, enfermedad celíaca, genotipos de arroz

Soaking and extrusion effects on physicochemical parameters, phytic acid, nutrient content and mineral bio-accessibility of whole rice grain

Abstract A combination of soaking and extrusion processes of whole rice grain was studied. The effects of temperature (35–55 °C) and time (24–48 h) of soaking treatment on phytic acid (PA), protein and ashes losses using a factorial design were evaluated. Taking into account ash, protein and PA losses, whole rice was soaked 24 h at 45 °C and extruded using a Brabender single screw extruder. Effects of extrusion temperature (160–190 °C) and moisture content (14–19 g/100 g) on product characteristics were evaluated using surface response methodology. Values corresponding to the different responses were: Expansion (1.64–3.28), Specific Volume (5.68–11.06 cm3/g), Water absorption (3.41–4.43 mL/g) and Solubility (45.44–66.20 g/100 g). The content of PA was reduced from 740.09 to 163.47 mg/100 g (77%) after both processes, resulting in a higher mineral bio-accessibility, and a 7.3% decrease of protein digestibility. Total soluble phenolics and trolox equivalent antioxidant capacity (TEAC) were affected according to the treatment. Both treatments were important to obtain a nutritionally improved whole grain product.

Effects of popping and extrusion processes on some hydration properties of amaranth

The effects of popping and extrusion processes on some of the hydration properties of Amarantus cruentus, which had already been degermed and dehulled, are discussed. Response surface methodology was used to analyse the effect of process variables (temperature and moisture) on hydration properties, evaluated by water solubility (S) and by amylographic retrogradation (R) . Results show that precooked flours obtained by popping have a very high suspension consistency with low or intermediate S, while those obtained by extrusion have very high S but a much lower suspension consistency. The high S values for extruded samples are even higher than those for extruded waxy types of cereals. The effects of the variables on each response depend on each case. S increases as temperature (T) and moisture (M) increase in both processes, although in extrusion, a maximum value was observed at 200 oC and about 15% M. On the other hand, an inverse variable effect is observed for R; a minimum value is observed with extruded samples at about 14% M and for the whole T range, while a typical saddle-shaped surface is obtained for popped samples, with maximum values found at about 14 % and 18 % M for the two extreme T values, the highest and lowest, respectively. Another interesting effect is that the S-R pair values corresponding to popped samples do not fit the correlation between S and R, normally found with extruded samples. We can conclude that with the application of both processes it is possible to obtain precooked flours that have a wide range of hydration properties.

Iron and zinc availability and some physical characteristics from extruded products with added concentrate and hydrolysates from bovine hemoglobin.

Abstract Four hydrolysates were obtained from bovine hemoglobin concentrate (BHC) and used to fortify extruded maize products. Extrusion was carried out with a Brabender single-screw extruder. Physicochemical properties from extruded products were measured. The iron availability was estimated by the dializability method, which measures the mineral dialyzed after a double digestion simulating physiological processes. The physicochemical properties of the extruded products were not affected by fortification, with the exception of total soluble solids. The enzymic hydrolysis increased the iron dializability with respect to the substrate. The highest value of iron dializability corresponded to the more hydrolysated sample. Extruded products fortified with BHC hydrolysates showed higher iron dializability than those fortified with BHC. However, iron dializability corresponding to BHC is lower than that expected from heme iron. Therefore, heme-iron availability is low when it is determined in the absence of meat proteins, and hydrolysis could increase potential iron availability.