Product Development and Quality Characterization of Pulse-based Extruded Ready to Eat Snacks

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Addis Ababa University


This study was aimed to enhance the value of pulse based food products and estimate its suitability for manufacturing of extruded snack products. Response surface methodology (RSM) was implemented to study the effect of extrusion process parameter and to optimize proximate and mineral composition, phytochemicals, physical properties (expansion ratio, bulk density and specific length), functional properties (WHC, WAI and WSI), microbial load and sensory quality attributes during extrusion process. Chickpea (Desi), Haricot Bean (Nasir), Maize (Melkassa 2) and Finger Millet (Taddesse) varieties were studied for proximate composition, phytochemical content, physical properties and functional properties. By applying mixture experimental design D-optimal software formulation containing 41.1g/100g Chickpea flour,16.0g/100g Haricot Beans flour, 31.9g/100g Maize flour and 10.9g/100 of Finger Millet flour was selected as the greatest source of energy (400.561kcal) and protein (18.09g/10g). The extrusion process variables were barrel temperature (120, 140 and 160°C) and screw speed (200, 270 and 340 rpm) feed moisture (15, 16.5 and 18%) through a die diameter of 6mm. The optimum extrudate which was obtained at 120oC (barrel temperature), 340rpm (screw speed) and 15% (feed moisture content) had 16.24% protein, 6.49 % fat, 2.66 % fiber, 2.51% ash and 74.01 % total CHO and 3.38, 2.22, 15.53, 90.47mg/100g for Fe, Zn, Ca, and Mg and 38.05 % phytate and 56.34% reduction of tannins was observed in this study. The maximum water absorption index (6.017g/g) and minimum load at break (16 N) values of the extrudates from texture analyzer (LLOYD level-05) were observed at 120oC, 340 rpm screw speed and 15% feed moisture content. Sensory quality evaluation of extrudate produced at 120oC, 340 rpm screw speed and 15% feed moisture content were significantly (P<0.05) better in color (8.22 ± 0.667), appearance (8.22± 0.441) crispiness (8.44 ± 0.527) flavour (8.33± 0.50), and overall acceptability (8.33 ± 0.50). The increment in mass flow rate from 19.84g/sec to 33.82g/sec was observed due to increase in screw speed from 200 to 340 rpm. Microbiological result showed that Coliform and E. coli were not detected at all in all extrudate. The total plate count and yeast and mold count analysis was found in the safe limit according to FAO and WHO. In conclusion 120oC barrel temperature, 340 rpm screw speed and 15% moisture content have been found to be ideal operating variables for pulse-based extrudate development. Key words: - Haricot beans, finger millets, Maize, response surface methodology, mixture design, ready to eat snacks.



Haricot Beans, Finger Millets, Maize, Response Surface Methodology, Mixture Design, Ready To Eat Snacks