15F-31 |
Double-screw extrusion of tuna, corn flour or wheat flour blends under optimum operational conditions |
H. J. Kim1, B. K. KIM2, and K. C. Rhee1. (1) Food Protein Research and Development Center, Texas A&M University, Cater Mattil Hall, College Station, TX 77843-2476, (2) Department of Food Engineering, Dan Kook University, San-29, Anseo-Dong, Cheonan, 330-714, South Korea Incorporation of fish could introduce inherent foreign flavor and inferior texture when it is extruded with other ingredients. Tuna, which is one of the world's most popular fish, may be a good candidate to be incorporated into extruded products. Nutritious snacks at reasonable cost could be developed using low-grade tuna flesh and cereal ingredients. To determine the extrusion conditions for a plant-scale double-screw extruder to produce snack-type foods using tuna-cereal ingredients and characterize the products. The feed was formulated with corn or wheat flour and tuna at 3, 6, and 10% (w/w) substitution levels. The flesh of skipjack tuna (Euthynnus pelamis) used for canning was chopped before mixing with other ingredients including water. The operating conditions for the extruder (Wenger Model TX-52) were 10 mm nozzle diameter, 190 rpm screw speed, 120oC process temp, and 1,900 psig process pressure. Expansion ratio (ER), bulk density (BD), fracture characteristics (FC), hardness, proximate composition, and color of extrudates were analyzed. No serious problem was experienced through the operation, even using feed material of 10% tuna at 13% moisture content. The extrudates ranged 8.3-14.5% in protein and 0.5-0.8% in ash, along with much less fat contents. Corn flour showed higher ER and lower BD values than wheat flour. The incorporation of tuna, up to 6%, caused increased expansion of the product until ER dropped again at 10%. FC and hardness were of similar tendency to ER, especially evidenced with wheat flour which inherently expanded less. As the tuna content increased, the extrudate turned lighter (corn), darker (wheat), reddish (wheat) or greenish (corn) while yellow tone remained less affected. Extrusion of tuna and cereal is a promising approach to produce low-cost, nutritious snacks of milder flavor. This technology could exploit the use of relatively low grade tuna flesh not used for canning.
Session 15F, Product Development
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