Physicochemical Characterization Of a Third- Generation Snack Produced By Extrusion Process From Blue Corn Flour And Corn Starch.

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1 TOPIC: Functional Foods FF-76 Physicochemical Characterization Of a Third- Generation Snack Produced By Extrusion Process From Blue Corn Flour And Corn Starch. Camacho-Hernández, I.L. 1,2, Navarro-Cortez, R. 2, Ochoa-López, M.E. 2, Aguilar-Palazuelos, E. 2, Zazueta-Morales, J.J. 2., Gómez-Aldapa, C. 1, Gallegos-Infante, J.A. 1, Rocha-Guzmán, N E. 1, González-Laredo, R.F Doctorado en Ciencias en Ingeniería Bioquímica, Instituto Tecnológico de Durango. Durango, Durango, México., Boulevard Felipe Pescador # 1830 Oriente, CP 34080, Durango, Durango. 2 Maestría en Ciencia y Tecnología de Alimentos, Universidad Autónoma de Sinaloa, Culiacán, Sinaloa, México. *Direct inquiries to autor Camacho-Hernández I.L. lcamachoh@gmail.com Introduction Snack industry encompasses a variety of markets, they are widely consumed in Mexico regardless of social status and age, being salty and spicy snacks the most consumed. Snacks produced by extrusion technology have technical, quality, versatility, and cost advantages. From extruded snacks third generation snacks have highlighted. In Mexico, corn and corn starch are the main raw material for production of snacks and there are several races that have natural pigments in their composition such as anthocyanins, which are considered safe for human consumption and can be used as nutraceutical additives. In addition, it has been suggested that anthocyanins can prevent oxidative damage caused by active oxygen radicals in living systems. Ingestion of these natural pigments can contribute to health of some sectors of the population. The aim of this study was to evaluate the effect of temperature ( C) and feed moisture (20-34%) on physicochemical and structural properties of extruded third-generation snacks expanded by microwave, made from integral blue corn (Zea mays L.) flour and corn starch. The products were produced using a laboratory extruder with a rectangular die output area of 1.5x20 mm and a central composite rotatable design were used for analysis and optimization of the data.the mixture utilized was 65% integral blue corn flour and 35% corn starch. Physicochemical and functional characteristics were determined on products extruded and expanded by microwave. physicochemical characteristics were expansion index (EI), penetration force (PF) and specific mechanical energy (SME), functional property was anthocyanin content. Materials and Methods Extrusion process Extrusion experiments were performed using a laboratory-scale single screw extruder. The barrel had three sections with independently controlled electric heaters and a 2:1 compression ratio. A rectangular die with an internal dimension of mm. Screw speed was 80 rpm and the die temperature was 75 C. Temperature and feed moisture used in the extrusion process, were set according to the experimental design. The extruded material was cut into approximately 2.5 cm, these were dried at room temperature for 24 h at moisture content between 9-13%, and stored in polyethylene hermetic bags for further analysis. The blue corn (Zea mays L.) flour was mixed with corn starch in a 65:35 ratio and added monoglycerides 0.1%, to improve the appearance of the extruded product. Flour samples used during the extrusion process were adjusted to the feed moisture from 20 to 34% according to the experimental design. A laboratory mixer (Kitchen Aid, Model K5SS, Michigan, USA) at low speed was used. Expansion of pellets The pellets were expanded using a conventional microwave oven (LG brand, model R-501CW), with a power of 900 W and Hz, 26 sec. 732

2 Physicochemical Methods Expansion index (EI) Expansion index was determined according to the methodology reported by Penfield and Campbell (1990) (7) and Boischot and others (2003) (3) and (7). It was reported as the ratio of the volume of expanded products and the volume of the unexpanded pellets. Thirty replicates were taken per treatment. Penetration force (PF) Was determined in expanded products, using a penetrometer Chatillon model TCD 200 (Vienna Court, Lammas Road, Godalming, Surrey, UK). A flat tip cylindrical probe of 2 mm diameter was used with a penetration depth of 3mm and a rate of descent of 0.83mm.s -1. Thirty replicate were taken and the values per treatment were reported in Newton (N). Specific mechanical energy (SME) Was calculated using the values for torque (T, Nm), speed screw (s, rpm) and feed rate (F, g/min); SME= (2p x T x s) / F, Batterman and others (1999) (2). SME is defined as the net mechanical energy input divided by the mass flow rate required by the extruder to turn the screw. Anthocyanins content Was carried measuring the absorbance of ethanolic extracts at ph 1.0 Abdel-Aal y Hucl (1999) (1). A ground sample (1g) was weighed in a centrifuge tube and 8 ml of acidified ethanol (ethanol and HCl 1.0N, 85:15, v/v) was added. The solution was mixed and adjusted to ph 1 with 4N HCl. The resulting solution was shaken for 30 min, readjusted to ph 1 if necessary. The tube was centrifuged at 3220 rpm for 30 min, and the supernatant was poured into a 25 ml volumetric flask and made up to volume with acidified ethanol. Absorbance was measured at 535 nm against a reagent blank. Anthocyanin content per sample (mg/kg) was calculated as cyanidin 3-glucoside: C = (A/e) (vol/1,000) MW (1/sample wt) 10 6 where C is anthocyanins content (mg/kg), A is absorbance reading, e is molar absorptivity (cyanidin 3-glucoside = 25,965 cm 1 M 1 ), vol is total volume of anthocyanin extract, and MW is molecular weight of cyanidin 3-glucoside = 449. Statistical analysis Response surface methodology (RSM) was used to predict the experimental behavior of data using a central composite rotatable experimental design with α=1.414 Table 1. Factors were barrel temperature (T) and feed moisture (FM). The data analysis was tried using the Design Expert (8) version statistical software. Results and Discussion Statistical analysis showed values R 2 adjusted values =0.76. The parameters EI and PF showed lack of fit, Table 2. All the responses, EI, PF, SME and anthocyanins content were significantly, influenced by the interaction barrel temperature-feed moisture (p< 0.001). 733

3 Table 1. Experimental design of blue maize extrusion. Independent Variables Treatment Coded Actual X 1 X 2 Temperature ( C) Feed Moisture (%) Table 2. Statistical analysis for responses variables in blue maize extrusion. Response R 2 Adjusted CV(%) Fvalue p of (model) Lackof-fit EI <0.001 <0.001 PF <0.001 <0.001 SME < ANTHOCYANINS < CV=Coefficient of variation; EI=Expansion index; PF=Penetration force; SME=Specific mechanical energy. Expansion index (EI) Figure 1A shows the EI graph, the range of values was from 1.91 to 4.80; the minimum value was obtained at 99 C and 27% of feed moisture and the higher value was obtained at 120 C and 20% of feed moisture. EI values decrease with decreasing or increasing the extrusion temperature, especially at low feed moisture values. On the other hand, generally the EI increases with feed moisture this behavior may be related to the degree of gelatinization starch. Penetration force (PF) Figure 1B shows PF experimental values within a range of 8 to 45.5 N. The higher value of PF was obtained at 105 C and 22% feed moisture and the lowest value was obtained at 120 C and 19.93% feed 734

4 moisture. This result may be related to the degree of starch gelatinization, dietary fiber present in the corn, and the interactions between lipids and proteins the grain of corn. A Figure 1. Effect of barrel temperature and feed moisture on expansion index (A) and penetration force (B) of third generation snacks expanded by microwave oven. B Specific mechanical energy (SME) Figure 2A shows SME decreased as temperature increased, as well as feed moisture increased. A decrease in EME is indicative of a decrease in the severity of the process by the water effect lubricating. The experimental values of SME were within a range of 80.4 to J/g, the minimum value of SME was obtained at 120 C and 34.07% feed moisture and the higher value was obtained at maximum temperature of 105ºC and 22% feed moisture. This result is consistent with Chang and others (1999) (6), who reported that an increase in barrel temperature decreased the product viscosity inside the extruder and the SME decrease. Anthocyanins content The anthocyanins content in the mixture without extruding was mg / kg and the anthocyanins content in blue corn meal was 379 mg / kg, this value is similar to that reported by Del Pozo-Insfran and others (2007) (4) in blue corn of the same variety. The experimental values of anthocyanins content obtained in the different treatments were in the range of to 82.3 mg/kg, these values were obtained in temperature and feed moisture of 105ºC and 22%, 135ºC and 32% respectively, Figure 2B. According to obtained data there was a decrease from 70 to 85% anthocyanins compared to the mixture without extruding, similar results were reported by Camire and others (2000) (5), this authors extruded corn with concentrated blueberry and grapes, finding a loss of anthocyanins of 70% for samples with grape and 90% for blueberry samples. 735

5 A B Figure 2. Effect of barrel temperature and feed moisture on specific mechanical energy (J/g) (A) and anthocyanins content (B) of third generation snacks expanded by microwave oven. Conclusions The mathematical model used in data analysis was appropriate for the evaluated responses. According to data obtained in this research project, it is feasible to use integral blue corn flour as raw material for the manufacture of a third-generation snack with acceptable physicochemical properties. More studies are necessary to evaluate nutraceutical characteristics of third generation snacks made from blue corn flour and starch, as well as an analysis sense to know the opinion of the consumer. References 1. Abdel-Aal, Young JC, Rabalsky I Anthocyanin composition in black, blue, pink, purple and red cereal grains. J Agric Food Chem 54(13): Batterman-Azcona SJ, Lawton JW y Hamaker BR Effect of specific mechanical energy on protein bodies and a-zein in corn flour extrudates. Cereal Chem. 76: Boischot C, Moraru CI, Kokini JL Factors that influence the microwave expansion of glassy amylopectin extrudates. Cereal Chem 80(1): Del Pozo-Insfran D, Serna-Saldivar OS, Brenes CH, Talcott ST Polyphenolics and antioxidant capacity of white and blue corns processed into tortillas and chips. Cereal Chem 84(2): Camire ME, Camire A, and Krumhar K Chemical and nutritional changes in foods during extrusion. Crit rev food Sci Nutr 29(1): Chang YK, Martínez-Bustos F, Park TS, Kokini JL The influence of specific mechanical energy on cornmeal viscosity measured by an on-line system during twin-screw extrusion. Braz J Che Eng 16(3): Penfield MP, Campbell AM Experimental Food Science. In: Academic Press Inc, editors. 3 rd Edition. USA: California. p: