Efecto de la extrusión-cocción en la formación de almidón resistente.

El objetivo de este estudio fue evaluar la formación de almidón resistente y propiedades físicas en harinas obtenidas después del proceso de extrusión-cocción y almacenamiento a baja temperatura. Se utilizó almidón de maíz nativo para el proceso de extrusión con un diseño experimental de 5 niveles y tres variables temperatura, velocidad de tornillo y humedad, produciendo 20 experimentos estudiados con metodología de superficie de respuesta para conocer el efecto de estos en las variables en índice de absorción de agua (IAA), índice de solubilidad en agua (ISA), cantidad de almidón resistente (AR) y propiedades térmicas como entalpia (ΔH) y temperatura de gelatinización Tg). La respuesta de superficie para IAA fue un máximo a 112.4 °C, 269 rpm y 27.4 % humedad, la respuesta para el ISA fue un punto silla a 204.7 °C, 282 rpm y 71 % humedad, el AR generó un mínimo a 102.4 °C, 253 rpm y 29 % de humedad, para la ΔH se generó un punto silla a 98.5 °C, 244 rpm y 48 % de humedad, la Tg dio un punto silla a 102.4 °C, 265 rpm y 32 % de humedad. El valor máximo de AR fue de 1.14 g / 100 g

Determination of Phenolic Compounds in Blue Corn Flour (<i>Zea mays</i> L.) Produced and/or Metabolized by <i>Colletotrichum gloeosporioides</i> in a Fermentation Process

Phenolic compounds are secondary metabolites produced by plants, and their study has been increased in recent years due to their ability to improve human health. The aim of this work was the determination of phenolic compounds presents in blue corn flour before and after a fermentation process, where different proportions were used of blue corn (Zea mays L.) flour and Czapek Dox culture medium (90 mL of culture medium with 10 g of blue corn flour, 80 mL of culture medium with 20 g of blue corn flour and 70 mL of culture medium with 30 g of blue corn flour) and were fermented at 3 different times (20, 25 and 30 days) with the Colletotrichum gloeosporioides fungus. A determination of the phenolic compounds was carried out with five standard solutions, which were cyanidin 3-glucoside (CYA), pelargonidin 3-glucoside (PEL), chlorogenic acid (CLA), quercetin (QRC) and cinnamic acid (CA). The obtained results showed the presence of CA and PEL. The most abundant phenolic compound in the fermented samples was CLA over the naturally occurring compounds in blue corn, which are CYA and PEL. QRC was the phenolic compound with the lowest concentration in blue corn flour samples fermented with Colletotrichum gloeosporioides

Physicochemical properties of frozen tortillas from nixtamalized maize flours enriched with β-glucans

AbstractEffects of different β-glucan concentrations in maize flour on the properties of frozen maize tortillas were evaluated. Masa (dough), pre-cooked (PTs), frozen (FTs), thawed (TTs), and cooked tortillas (CTs) were made and analyzed. Moisture content of masa and tortillas significantly decreased as β-glucan concentration increased; however, the water absorption capacity (WAC), ice melting enthalpy, and frozen water in FTs increased. Texture and color of the masa, PTs, and CTs as well as sensory analysis showed differences only between tortillas with 0% and 4% β-glucans. β-glucans did not affect the texture of CTs. Soluble fiber increased by over threefold and fivefold in tortillas with 2% and 4% β-glucans, respectively, than in those without β-glucans. This result was consistent with the observed structural changes in tortillas, showing an increase in high-fiber aggregates with increasing β-glucan concentration. Tortillas with 2% β-glucans showed acceptable physicochemical, functional, and sensory properties, but over three times the soluble fiber. Therefore, it is possible to obtain frozen tortillas with high fiber content and increase their shelf life for subsequent cooking while maintaining good properties

Anthocyanins and Functional Compounds Change in a Third-Generation Snacks Prepared Using Extruded Blue Maize, Black Bean, and Chard: An Optimization

The effect of extrusion cooking on bioactive compounds in third-generation snacks (TGSE) and microwave-expanded snacks (MWSE) prepared using black bean, blue maize, and chard (FBCS) was evaluated. FBCS was extruded at different moisture contents (MC; 22.2–35.7%), extrusion temperatures (ET; 102–142 °C), and screw speeds (SP; 96–171 rpm). Total anthocyanin content (TAC), contents of individual anthocyanins, viz., cyanidin-3-glucoside, malvidin-3-glucoside, pelargonidin-3-glucoside, pelargonidin-3-5-diglucoside, and delphinidin-3-glucoside chloride, total phenolic content (TPC), antioxidant activity (AA), and color parameters were determined. TAC and individual anthocyanin levels increased with the reduction in ET. ET and MC affected the chemical and color properties; increase in ET caused a significant reduction in TPC and AA. Microwave expansion reduced anthocyanin content and AA, and increased TPC. Extrusion under optimal conditions (29% MC, 111 rpm, and 120 °C) generated products with a high retention of functional compounds, with high TAC (41.81%) and TPC (28.23%). Experimental validation of optimized process parameters yielded an average error of 13.73% from the predicted contents of individual anthocyanins. Results suggest that the TGSE of FBCS obtained by combining extrusion and microwave expansion achieved significant retention of bioactive compounds having potential physiological benefits for humans

Physicochemical Changes and Resistant-Starch Content of Extruded Cornstarch with and without Storage at Refrigerator Temperatures

Effects of extrusion cooking and low-temperature storage on the physicochemical changes and resistant starch (RS) content in cornstarch were evaluated. The cornstarch was conditioned at 20%–40% moisture contents and extruded in the range 90–130 °C and at screw speeds in the range 200–360 rpm. The extrudates were stored at 4 °C for 120 h and then at room temperature. The water absorption, solubility index, RS content, viscoelastic, thermal, and microstructural properties of the extrudates were evaluated before and after storage. The extrusion temperature and moisture content significantly affected the physicochemical properties of the extrudates before and after storage. The RS content increased with increasing moisture content and extrusion temperature, and the viscoelastic and thermal properties showed related behaviors. Microscopic analysis showed that extrusion cooking damaged the native starch structure, producing gelatinization and retrogradation and forming RS. The starch containing 35% moisture and extruded at 120 °C and 320 rpm produced the most RS (1.13 g/100 g) after to storage at low temperature. Although the RS formation was low, the results suggest that extrusion cooking could be advantageous for RS production and application in the food industry since it is a pollution less, continuous process requiring only a short residence time