1. Field of the Invention
The present invention relates to an extruded food product and a new method and apparatus for preparing such extruded food product, and more particularly to a new extruder line comprising an extruder and conveyor system of the invention for preparing an extruded food product that is wide in all cross-section dimensions.
2. Background of the Prior Art
Foods that are sold as snack products enjoy wide popularity with consumers. Typical examples of snack food products are potato chips, corn chips, corn puffs, and the like. Generally, snack foods are consumed as a source of pleasure, rather than nourishment. Thus, the aesthetic appeal of such snack foods is paramount. Shape, size, and color, as well as the general appearance and taste of a snack food product are very important to the market success of a snack food. A further characteristic that improves market appeal in a snack food is its texture, or crunch.
Manufacturing food products by cooking and extruding the ingredients in a cooking food extruder is well known in the art and is commonly used in the manufacture of snack foods. In order for the food ingredients to cook properly, the ingredients must be evenly heated in the extruder barrel and continually mixed by the extruder screw(s) to obtain a homogenous and uniformly shaped product. The intense pressure and high temperatures within the extruder causes the starch within the food material to gelatinize and cook.
Extruders in the food-processing field are sold as single or dual units, and are selected based on the particular food application. The screws of the dual and single screw extruders include segments with helical flights referred to as "feeding elements" for transporting the food ingredients toward the die plate and include other segments with kneading and mixing lobes, referred to in the art as "paddles." By mixing and extruding a food product in the extruder barrel, the food product is more homogeneous.
In general, dry ingredients in prescribed proportions are blended and then introduced to a cooking extruder, possibly with water and/or other ingredients. The blending step may involve the addition of liquid ingredients to dry ingredients to adjust the moisture level. Through a combination of shear, pressure, and heat of the extruder, the starch within the food is gelatinized. The final shape of the food product is formed by rapid expansion when the cooked ingredients exit the cooking extruder through a number of orifices in a die plate, e.g., by moving from a confined zone of high pressure to an unconfined zone of much lower pressure, i.e., the atmosphere. Upon discharge from orifices in the die plate of the extruder into the atmosphere, the extrudate rapidly expands to its final form and is then cut into discrete lengths by a rotating cutter positioned adjacent the extruder die head. The length of the cut pieces is a function of the speed of the cutter rotation and the speed of extruding.
One type of snack food that can be made by cooking extruders is the French fried potato, or French fry. This snack food is made by blending potato and corn, or any other starch based grain, and processing the blend in a cooking extruder. The addition of oil and spice occurs after the drying step. In known prior methods of processing French fries, the maximum cross-sectional dimensions that have been achievable, while maintaining significant extruded food product crunch and shape uniformity, are less than 0.3 inch.times.0.4 inch. When extruding starch based grains, it is generally known that as the cross-sectional dimensions of the extruded food product increases the food product cell size (size of air pockets in the formed extruded food product) also increases, which decreases the desirable crunchy texture of the food product. It is recognized that a crunchy, uniformly shaped, French fry of increased size, generally called a "steak fry," may be more attractive to many purchasers. Even "small" increases in size, for example, a steak fry with a cross-section equal to 0.5 inch.times.0.5 inch, while maintaining significant crunch and shape uniformity, would be significant in this highly competitive field.
Two patents discussed briefly below disclose extruders and methods for producing extruded snack food products. U.S. Pat. No. 3,925,563, entitled Preparing An Extruded Puffed Snack Product, discloses a die plate in FIGS. 2 and 3, having a series of plus (+) shaped orifices (37) for extruding a food product that subsequently expands to a square cross section. The apparatus and method disclosed in the '563 patent produces a snack food having a cross sectional shape with each side of the square being less than 0.33 inches.
U.S. Pat. No. 4,985,262 is for a Process for Preparing A Snack Product. The '262 patent discloses a process for coating an extruded fannaceous-based French fry with a combination of flour, aqueous liquid, and oil. However, the invention of the '262 patent describes an irregularly shaped product having cross sectional dimensions in the range of only 0.30-0.40 inches.
Using currently available extruders and extruder assembly lines, attempts at increasing the length of each cross-section side of rectangular extruded food products, for example, results in a highly undesirable extruded snack food product. As the die orifice size is increased to form ever-larger extruded food products, the expanded extrudate formed is highly inconsistent in shape, weight and density. It was also found that when a large extruded food product (extrudate) was cut immediately adjacent the die plate discharge end as is the normal practice in the art, the ends were crimped, causing the resulting product to have an extremely undesirable shape and look.
With the foregoing in mind, it becomes a general object of the present invention to provide an extruder line for preparing an extruded food product that is wide in all cross-sectional dimensions.
It is also an object of the present invention to provide an extruded food product that has cross sectional dimensions of more than 0.40 inches per side of a rectangular extruded food product.
It is a further object of the present invention to provide a crunchy extruded snack food product that has cross sectional dimensions of approximately more than 0.5 inches per side of a rectangular extruded food product.
It is another object of the present invention to provide an extruded food product that is uniform in cross sectional shape and uniform in length of piece.
It is another object of the present invention to provide an extruder having an expansion chamber within the extruder die head for providing an increase in volume of food mix immediately preceding the extruder die plate.
It is yet another object of the present invention to provide an extruder line having an extruder with a discharge feed element immediately preceding the expansion chamber of the present invention for providing an increase in volume of food mix at the exit end of the extruder barrel.
It is a further object of the invention to provide an extruder line having a conveyor system for conveying the extrudate strands through ambient air to cool and solidify the extrudate.
It is another object of the invention to provide an extruder line having an air nozzle to cool and solidify the extrudate.
These and other objects will become more apparent from the following disclosure and claims.