Patent Description:
Many food products are provided in frozen or refrigerated ready-to-cook form and many such products have texturizers, such as bread crumbs, intended to provide appealing crispiness/crunchiness to the cooked products.

In many instances, their textural qualities are difficult to reach as a result of cost optimized yields; freeze-thaw abuse; frozen or refrigerated storage; food service holding practices, including warming cabinets, steam tables and heat lamps; and cooking methods, including humidity controlled ovens and microwave reheat.

RS4-type resistant starches are chemically-modified, highly-cross-linked starches, resistant to digestion by alpha-amylase and are widely used to provide dietary fibre to a wide variety of food products, such as bread, to provide a pre-biotic fibre source for gut health. These starches may be manufactured by procedures described in <CIT> and <CIT>. Examples of RS4 resistant starches include Fibersym® (MGP), PenFibe™ RS (Penford Food Ingredients) and ActiStar® RT (Cargill) resistant starches. <CIT> describes expanded products with high protein content. <CIT> describes the production of low calorie, extruded, expanded foods having a high fiber content.

It is an object of the present invention to overcome the deficiencies of the prior art frozen or refrigerated ready-to-cook food products.

Further and other objects of the present invention will become apparent to those skilled in the art from reading the following summary of the invention and the detailed description of the embodiments described and illustrated herein.

The present invention provides novel and inventive texturizing crumb products and other cereal grain-based products utilizing resistant starch as a portion of the starch component of the product, for coating food products.

In the present invention, RS4 resistant starch, one embodiment, from wheat, is used in conjunction with high pressure short time (HPST) extrusion technology to produce textured crumb materials for coating frozen or refrigerated food products. The present invention delivers superior textural qualities to assist in withstanding the problems associated with conventional frozen or refrigerated food coatings, particularly in microwave reconstituted foods. RS4 sources may also include, among others, potato and tapioca.

Further advantages of the present invention will become apparent to those skilled in the art from reading the following detailed description of the embodiments described and illustrated herein.

The texturizing crumbs provided herein are comprised of a cereal base, such as wheat, rice or corn, and contain RS4 resistant starch up to <NUM> wt% of the formulation, in one embodiment, up to about <NUM> wt% of the formulation, in another embodiment, from about <NUM> to about <NUM> wt% of the formulation, in another embodiment, from about <NUM> to about <NUM> wt% of the formulation, in another embodiment, from about <NUM> to about <NUM>% wt% of the formulation, in another embodiment, from about <NUM> to about <NUM> wt% of the formulation, and in another embodiment, from about <NUM> to about <NUM> wt% of the formulation. HPST extrusion is required in conjunction with the RS4 resistant starch to produce crumbs of the present invention with the desired textural properties and performance in the finished product application.

HPST extrusion technology is a process whereby a food material is forced to flow, under one or more varieties of conditions of mixing, heating and shear, through a die which is designed to form and/or puff/expand the ingredients (see <NPL>). HPST extrusion-cooking is carried out in a food extruder which generates large amounts of mechanical energy and shear. Food extruders are machines in which the main operative body is one screw or a pair of screws fitted in a barrel. During baro-thermal processing (typically pressures of up to about 20MPa and a temperature of about <NUM>), the material is mixed compressed, melted and plasticized in the end part of the machine as shown in <FIG>, wherein <NUM> is the engine, <NUM> is the feeder, <NUM> is the cooling jacket, <NUM> is the thermocouple, <NUM> is the screw, <NUM> is the barrel, <NUM> is the heating jacket, <NUM> is the head, <NUM> are the dies, <NUM> is the cutter, Section I is the transport section, Section II is the compression section, and Section III is the melting and plasticizing section [(see<NPL>)]. At the exit of the extruder, the mixed ingredients are forced through openings in a perforated plate or die with a design specific to the food and are then cut to a specified size by a rotating knife (cutter).

Crumbs of the present invention have desirable textural characteristics such as crispiness, persistence of crisp and fracturability, which are retained even in coated food systems that have been subjected to a variety of stresses including freeze/thaw cycling, extended hold times and microwave reconstitution. In contrast, coating crumbs produced with a CMKD process do not retain their textural characteristics in stressed coating systems, losing crispness and becoming increasingly cohesive in these circumstances.

Using Differential Scanning Calorimetry (DSC), RS4 containing crumbs of the present invention exhibit glass transition temperatures (Tg) between about <NUM> to about <NUM>, even at a moisture level of about <NUM>%, which is consistent with moisture levels present in the outer layers of coated food items subjected to stress such as freeze/thaw cycling or microwave reheat. The glass transition is associated with "glassy" textural attributes such as crispiness and fracturability. The magnitude of Tg is reflected in the heat flow change or ΔCp of the sample. CMKD processed crumbs or crumbs produced using the HPST extrusion process of this invention, but without RS4 content, do not exhibit glass transition states at this moisture level.

When examined by Scanning Electron Microscopy (SEM) with <NUM> to 1000X magnification, RS4 containing crumbs of the present invention show a predominantly gelled and amorphous matrix due to the high shear of HPST extrusion. Intact resistant starch granules are sitting upon this matrix (see Figures land <NUM> to <NUM>). Crumbs produced in a HPST extrusion process but without RS4 do not show intact starch granules (see <FIG>, <FIG>, <FIG> and <FIG>). CMKD processed crumbs exhibit a large amount of intact starch granules, although embedded within a dough matrix of proteins, lipids and hydrocolloids (see <FIG>).

Cooked viscosity profile analysis using a Rapid-Visco Analyzer (RVA) identifies the degree to which starch granules, in this case within the crumb, are able to swell and rupture in a high moisture environment when heated to about <NUM>. <FIG> and <FIG> show differences in cooked viscosity profiles of HPST extruded and CMKD processed crumbs. RS4 crumbs of the present (see <FIG>) show high initial cold viscosities prior to heating, associated with highly gelatinized starch. The subsequent and relative low peak is associated with residual pasting potential and influenced by the intact RS4 starch granules. CMKD processed crumbs (see <FIG>) exhibit low cold viscosities due to the limited water holding capacity of the intact starch granules. During the heating phase, the starch granules of the CMKD processed crumbs take in water, swell, generate a significant viscosity peak and then rupture. The difference in water holding capacity on heating between HPST extruded RS4 crumbs and the CMKD processed crumbs has important effects on the cooked textural characteristics.

In a coated food product, long term freezer storage or freeze/thaw cycling has a water pumping effect, transferring moisture from substrate and inner coating layers to the outside layer. The HPST extruded RS4 containing crumbs of the present invention readily release this moisture without altering the state of the intact resistant starch granules, which themselves have poor water holding capacity. This results in improved textural properties upon cooking due to the ability of the crumbs of the present invention to undergo a glass transition under elevated moisture levels. Upon cooking CMKD processed crumbs, moisture is readily absorbed and held as the starch granules swell. The moisture is trapped within the crumb matrix and the glass transition is negated, resulting in poor textural properties exhibited as a soft and cohesive mass, so often associated with freezer storage abuse or microwave reconstitution.

This Example illustrates the use of RS4 resistant wheat starch in texturizing crumbs through HPST extrusion using a Wenger TX85 model, in accordance with the present invention.

Texturizing crumbs were made by extruding the mixture through a Wenger TX85 pilot extruder. The twin-screw extruder was configured with an L/D ratio of <NUM> and double cut-flight elements within the last three zones. The extrudate was particulated and the crumb products generated under varying shear conditions as influenced by die configuration, dry feed rate, added moisture, location of water addition and extruder RPM. These conditions influenced motor load and head pressure as shown in Table <NUM>.

Trials W120523-<NUM> and <NUM>-<NUM> contained no RS4 wheat starch. Although they were run under significantly different shear conditions, neither exhibited glass transition nor showed evidence of intact starch granules as seen by SEM (see <FIG> and <FIG>). The wheat flour base of trials W120523-<NUM> and <NUM>-<NUM> underwent a complete melt and formed an amorphous structure on cooling.

With the addition of <NUM> and <NUM>% RS4 wheat starch, in accordance with an aspect of the present invention, the SEM shows intact starch granules (see <FIG>) and the glass transition becomes evident even at <NUM>% moisture. These RS4 formulations exhibit a clear Tg between about <NUM> to about <NUM> with ΔCp increasing with the level of RS4.

W120525-<NUM> and W130416-<NUM> were both run with the same front, but different back die designs, the former with <NUM>% greater open area compared to the latter. This resulted in W130416-<NUM> experiencing significantly more shear, as indicated by the head pressure, and the subsequent crumb exhibiting glass transition. W120525-<NUM> did not undergo glass transition.

Crumbs containing RS4 (W120525-<NUM>, W130416-<NUM>), in accordance with an aspect of the present invention, exhibited crispy and fracturable textures in a coated chicken nugget application where the product was subjected to freeze/thaw cycling and microwave reheat. The counterpart non-RS4 crumbs offered little or no textural contribution in the same stressed conditions and were described as soft and cohesive.

This Example illustrates the use of RS4 wheat starch in texturizing crumbs made by HPST extrusion using a Wenger TX85 model extruder with alternate cereal bases; corn and rice, in accordance with the present invention.

All trials contained RS4 wheat starch and exhibited clear glass transitions and evidence of intact starch granules under varying shear conditions (see <FIG>). W120525-<NUM> and W130417-<NUM> rice-based formulations showed a significant difference in head pressure. Although the latter had the lower level of RS4 wheat starch and higher shear, the starch survives these conditions. The onset of the rice glass transition was delayed when compared to corn.

In finished product application on chicken nuggets subjected to freeze/thaw cycling and microwave reheat, rice-based crumbs with RS4 wheat starch, in accordance with an aspect of the present invention, exhibited light crispy textures with little cohesion, while the corn-base with RS4 wheat starch, also in accordance with an aspect of the present invention, provided some crisp/crunch with moderate cohesive character. Rice and corn-based controls without RS4 provided little or no texture in the abused conditions.

This Example illustrates the use of a RS4 wheat starch in texturizing crumbs made by HPST extrusion using a commercial scale Wenger TX144 model extruder, in accordance with the present invention.

Crumbs were made by extruding the mixture through a Wenger TX144 extruder. The twin-screw, <NUM> head extruder was configured with an L/D ratio of <NUM> and double cut-flight elements within the last two zones. The extrudate was particulated and the crumb products generated under varying shear conditions as influenced by added moisture and extruder RPM. These conditions influenced motor load and head pressure as seen in Table <NUM>. Operating parameters for a commercial extrusion process were scaled-up from the Wenger TX85 pilot trials and did not require as wide a range of study.

As is evidenced by DSC and RVA analysis, both wheat and rice RS4 containing formulations, in accordance with aspect of the present invention, exhibited glass transitions and RS4 starch granule integrity supported by depressed cooked peak viscosities versus their non-RS4 controls (see <FIG>).

KB <NUM> and KB <NUM>, in accordance with aspect of the present invention, offered improved textural properties versus non-RS4 crumbs (KB <NUM> and KB <NUM>) in a coated chicken nugget application subjected to storage abuse and microwave reheat. The wheat based KB <NUM> provided a harder, crunchier texture versus the lighter crisp texture of the rice-based KB <NUM>. Formal sensory results against CMKD process control are presented in Example <NUM>.

This Example illustrates the use of RS4 resistant wheat starch, in combination with alternate starches, in texturizing crumbs made by HPST extrusion using a Wenger TX85 model as in Example <NUM>.

In this comparison, trials were run under similar conditions, focusing on the effect of alternate starches. These high amylose starches, with some resistance character, did not perform the same as the RS4 types under abuse conditions in coating crumb application. SEM analysis shows an amorphous matrix, but with no intact starch granules. The high amylose rice starch Remy B7 showed good textural and visual attributes on its own or in combination with RS4, but only under non-abused conditions. The RVA cooked peak viscosity analysis shows elevated peaks in the crumbs containing only added high amylose starch (see <FIG>). This indicates greater swelling capacity and the subsequent moisture retention upon heating within these coating crumbs, affecting negatively their textural qualities.

This Example illustrates the use of RS4 resistant wheat starch in texturizing crumbs within a CMKD process, the process as described in <CIT>.

RS4 wheat resistant starch within the CMKD process does not exert the same effect on analytical results or performance characteristics as in the HPST extrusion process. Survival of intact native starch granules has the greatest influence and significantly masks any performance enhancement by the RS4 starch. No glass transition is observed with the RS4 addition. The RVA cooked peak viscosity (see <FIG>) shows the elevated peak as produced by native starch (KB <NUM>) and its depression as affected by the dilution with RS4 in the CMKD process (KB <NUM> A/B). Although the depressed peak is characteristic of HPST extruded crumbs made with RS4 in accordance with the present invention, the lack of any cold viscosity in the CMKD processed crumbs with RS4 indicates native starch granules are still intact, embedded in the dough matrix, available to swell and retain moisture during the cook cycle of the coated product.

CMKD processed crumbs with RS4 show no significant improvement in crispiness, fracturability or persistence in a stressed coating application on chicken nuggets compared to the KB <NUM> control without RS4 and negligible texture when compared to HPST extruded RS4 containing crumbs of the present invention. Additional textural comments focused on an increased chalkiness character in CMKD processed crumbs containing RS4.

This Example describes the finished product textural performance of HPST extruded crumbs containing RS4 resistant wheat starch, in accordance with the present invention, against control crumbs manufactured in a CMKD process.

The crumbs were applied in a coating sequence to chicken nuggets using a multi lamination pilot process. Both par-fry/freeze and par-fry/cook/freeze processing scenarios were investigated to expand versatility for reheat from frozen; oven or microwave. The reheated nuggets were evaluated by a panel of professional tasters. Both stressed and non-stressed reheated nuggets were evaluated for their textural qualities. The stressed versions had undergone freeze-thaw conditions of either a <NUM>-cycle freeze/thaw for <NUM> hours at <NUM> and subsequent re-freeze to -<NUM>, or one cycle of <NUM> hours at <NUM> with subsequent re-freeze to -<NUM>. Further comparisons were also made against products held under continuous frozen storage with no further abuse.

<FIG> compare the textural performance in a commercial retail (oven cooked) application of fully expanded crumbs produced from formulations containing RS4 resistant wheat starch with wheat (W120525-<NUM>, <NUM>% RS4), corn (W120525-<NUM>, <NUM>% RS4) or rice (W120525-<NUM>, <NUM>% RS4) flour bases, in accordance with the present invention, against those produced in a CMKD process with wheat flour (KB <NUM>). Control nuggets for each sample were not stressed, while stressed nugget samples underwent <NUM> freeze/thaw cycles. Crumbs of the present invention with wheat resistant starch generally maintained or improved in crispiness and persistence with reduced cohesiveness after freeze/thaw abuse while KB <NUM> decreased in crispiness and persistence. Amongst crumb samples with RS4 resistant wheat starch, the rice based crumb had the best overall texture after freeze/thaw abuse, followed by wheat and corn.

Tables <NUM> and <NUM> summarize the results of formal texture analysis of chicken nuggets with HPST extruded commercial scale produced KB <NUM> (<NUM>% RS4), in accordance with the present invention, and CMKD processed KB <NUM> after a <NUM> minute hold post cooking and <NUM> freeze/thaw cycles. Results were scored on a <NUM>-point hedonic liking scale for several textural attributes.

KB <NUM>, in accordance with the present invention, was significantly preferred for overall texture and for crispiness in both the <NUM> minute held and freeze/thaw abused scenarios. Panelists described the KB <NUM> as crispy and glassy with slight cohesion, while KB <NUM> comments described it as denser, less crispy and more cohesive.

<FIG> and Table <NUM> summarizes sensory results comparing textural attributes of chicken nuggets in a commercial retail application after freeze/thaw abuse and microwave oven reheat.

Commercial scale HPST extruded RS4 resistant wheat starch containing crumbs KB <NUM> (wheat base, <NUM>% RS4) and KB <NUM> (rice base, <NUM>% RS4), in accordance with the present invention, were compared against CMKD processed KB <NUM> as a control. Both KB <NUM> and KB <NUM> had significantly better crispiness and persistence versus the control. The wheat based KB <NUM> was preferred overall for texture. Additional texture panelist comments identified KB <NUM> as the driest coating with crispy/crunch character, KB <NUM> with a lighter crisp, and the control KB <NUM> as soft, wet and more cohesive.

Claim 1:
A textured crumb product, formed by high pressure short time (HPST) extrusion, wherein the product comprises up to <NUM> wt% RS4 resistant starch, and a cereal base, and wherein the HPST method comprises:
(a) mixing, compressing, melting and plasticizing the ingredients for producing the textured crumb product in the end part of an extruder;
(b) forcing the mixed ingredients through openings in a perforated plate or die; and
(c) cutting the product with a rotating knife;
and wherein the textured crumb product exhibits:
(i) a glass transition temperature from <NUM> to <NUM> at a moisture level of <NUM>% using differential scanning calorimetry; and
(ii) a predominantly gelled and amorphous matrix with intact resistant starch granules sitting on the matrix when examined under scanning electron microscopy with <NUM> to <NUM> magnification.