EXTRUSION PROCESS USING PREGELATINIZED STARCH TO PRODUCE PUFFED/EXPANDED FOOD PRODUCT

BACKGROUND OF THE INVENTION

The invention relates to a process for manufacture of extruded foods that may contain heat sensitive ingredients and/or ingredients associated with reduced expansion.

SUMMARY OF THE INVENTION

One aspect of the invention is an extrusion process for producing a puffed food. The process comprises: (1) providing a feed composition that comprises pre-gelatinized starch and at least one heat sensitive ingredient, such as fiber, protein, vitamins, omega 3 fatty acids, choline, flavors or sugars, and (2) extruding the feed composition through an extruder that comprises at least one die. The feed composition comprises sufficient water to plasticize the composition in the extruder, and the barrel temperatures are below about 6O ⁰ C. In some embodiments, the feed composition also comprises starch that is not pre- gelatinized. In one specific embodiment of the invention, the feed composition comprises 25-75% pre-gelatinized starch; 25-75% heat sensitive materials, and the balance starch that is not pre-gelatinized, on a dry weight basis.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Puffed foods with heat sensitive ingredients or ingredients that retard puffing in typical extrusion processes can be produced with pre-gelatinized starches under low temperature extrusion processing, e.g. the barrel temperature of all zones can be controlled under 60 ⁰ C. The use of instant or pregelatinized starch allows the puffing and the process parameters, including screw configuration, produce the fine cell structure consistent with a high quality product. The low temperature extrusion allows the incorporation of proteins, vitamins, flavors or other ingredients that would be degraded in a typical extrusion process.

The puffed products are fabricated from cooked farinaceous doughs that comprise, and optionally can consist essentially of 1) a pre-gelatinized starch or flour (e.g., an instantized starch or flour), which can comprise instantized starch granules or fragments of

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starch granules, typically in an amount of about 25% to about 75% of the overall composition by dry weight, 2) dried heat sensitive ingredients such as fiber, protein, vitamins, omega 3 fatty acids, choline, flavors or sugars, typically in an amount of about 20% to about 45%, by dry weight, and 3) a starch flour or powder, such as tapioca starch powder, corn flour, rice flour or wheat flour, which have sufficient water to plasticize the dough inside of extruder. This water may also include liquid forms of heat sensitive ingredients.

Suitable pre-gelatinized starches, heat sensitive ingredients, ingredients that can retard expansion and starch flours are known. For example, suitable pre-gelatinized starches include STA-SLIM ^® 150 tapioca starch and X-PAND'R ^® waxy starches, both of which are available from Tate & LyIe (Decatur, Illinois).

The novel extrusion process hydrates the pre-gelatinized starch inside of an extruder. The viscous pre-gelatinized starch forms a matrix that embeds heat sensitive ingredients or ingredients that can retard expansion Because of the high viscosity of the pre-gelatinized starch matrix, pressure at the die face builds, creating a puffing force that when released to atmosphere (going through the die), results in expansion of the matrix. To prevent degradation of heat sensitive ingredients or ingredients that can retard expansion the extruder barrel temperature can be controlled under 60 ⁰ C . The screw shearing zone is set up adjacent to last barrel that is next to the die (zone 5), and the vent is set up at the same zone (5) to release air and moisture. The fine cell structure of the puffed product is obtained because dough flow, in the last zone (6), is laminar when traversing the die holes.

The degree of puffing of the extrudate is as the same as "normal" extrusion processing.

EXAMPLES 1) Ingredients and Formula a. Prototype formulas (A, B, and C)

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(Pet = %) b. Each formula was dry blended in the ribbon blender, respectively, for extrusion processing.

2) Extrusion Processing a. Extruder: Buhler Twin Screw Extruder BCTL-42 model, available from the Buhler Group, Buhler AG 9240 Uzwil, Switzerland b. Extruder Screw Configuration Setting Up

c. 2 dies of 3.5 mm in diameter convergent die d. Extrusion Processing

i. Temperature profile of the extruder for each formula

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Product Zone 6 Zone 5 Zone 4 Zone 3 Zone 2 Tern ⁰ C Tem ^c C Tem ^c C Tem ^c C Tem ^c C Tem ^c C

Formula A 127 42 19 15 15 15

Formula B 133 42 18 23 23 24

Formula C 109 42 25 23 23 22

ii. Extruder Processing Parameters

The cutter speed was 1000 rpm for all runs. (SME = specific mechanical energy)

iii. Puffs Physical Attributes

3) Post Extrusion Processing

All the extrudates from extruder were dried in the convection oven at 200 ⁰ F for 20 minutes.

The preceding description is not intended to be an exhaustive list of every possible embodiment of the present invention. Persons skilled in the art will recognize that modifications could be made to the embodiments described above which would remain within the scope of the following claims.