Crisp edible material and method of preparing same

Abstract: Crisp edible material predominantly comprising 40 to 70% pure gluten protein and starch having an amylopectin to amylose ratio ranging from 8:1 to 25:1. A method of preparing an expanded crisp food material by extruding a mixture of predominantly 40 to 70% of pure gluten protein and 30 to 60% of starch having an amylopectin to amylose ratio of from 8:1 to 25:1 and up to 30 parts water per 100 parts solids at temperatures between 100 and 150°C and drying the extrudate.

Description: Crumbed food products, ie food products having a bread crumb coating, are known in a great variety and are both prepared in the kitchen for direct consumption and in the food industry for frozen or chilled storage and distribution. Generally accepted texture requirements for crumbing materials being light, not too hard and simultaneously crisp, which properties should be little or not influenced by usual humidity conditions prevailing during usual storage and shipping. EP 319 287 (Unilever) discloses a crisp edible material comprising a high heat-set protein level (greater than 30%, preferably greater than 50%, more preferably higher than 75% by weight), and optionally from 0 to 40% by weight starch. Extrusion Cooking edited by C Mercier, P Linko and J M Harper (1989) pp 265, 276 & 277 discloses that the amylose-amylopectin ratio is important in determining properties of starch-based extruded products. A 5-20% amylose level in starch is recommended to give adequate crispness and acceptable texture. Table 1 on page 277 illustrates that waxy maize starch has a lower water absorption index compared to normal starch. It is an object of the invention to provide crisp edible material showing a combination of the above properties as well as a method of preparing this material. The invention provides thereto a crisp edible material predominantly comprising gluten and starch, comprising amylopectin and amylose, which is characterized in that the pure gluten protein content ranges from 62% to 46%, the total starch content is from 27.2% to 45.4% and the ratio of amylopectin to amylose ranges from 12:1 to 24.4:1. Such crisp materials have a long keepability under high humidity conditions. This effect and these properties are particularly advantageous when the expanded material is used as a crumbing material. In this specification and claims percentages and parts are related to weights, unless otherwise indicated. The term "gluten" in practice is ambiguous: "commercial gluten" is a product containing about one tenth starch, the bulk i.e. roughly three quarters, being a proteinaceous product or "pure gluten protein", the balance being lipid and water. Analysis of one commercial sample being as follows: gluten protein 77%, starch 9%, lipid 6% and water 7%. For clarity the expressions "commercial gluten" and "pure gluten protein" are used throughout this specification and claims. Also for clarity the total starch content is referred to. This includes the starch content of the commercial gluten plus any additional starch. For preparing crumbs several processes are in use at the moment, the best known being; preparing a dough, allowing this to be blended with any leavening agent, then baking, drying and comminuting or extruding a low moisture mixture of the aforementioned dough at increased temperature and pressure, also known as cooker-extruding, drying and comminuting. Unexpectedly an expanded food material of acceptable hardness and a high crispiness which can fairly survive usual humidity conditions can be prepared by extruding a mixture of predominantly 46 to 62% of pure gluten protein and 27.2 to 45.4% of total starch content having an amylopectin to amylose ratio of from 12:1 to 24.4:1 and up to 30 parts water per 100 parts solids, although 20 parts or less is preferred, at elevated temperatures between 100 and 150°C and in particular between 120 and 140°C and drying the extrudate. Drying is preferably effected using a gas, e.g. warm air, having a temperature not exceeding 70°C. The above preferred conditions all contribute to obtaining a less hard, crispier and better moisture resisting product. For manufacturing crumbs the product so obtained can be comminuted to the desired particle size. The invention will be exemplified in the following examples of some at this moment preferred embodiments (Examples XIII, I and IV) and some comparative compositions (Examples XII, XIV, XV, II, III, V, VI, VII, VIII, IX, X, XI). Example I 70 parts commercial gluten containing 9% wheat starch, 30 parts waxy maize starch (1% amylose and 90% amylopectin) and 20 parts total water (including water in gluten and starch) were fed into a "Clextrel" cooker-extruder driven at approximately 175 revs/min. Inside the extruder a temperature developed of between 125 and 135°C. On emerging through a nozzle having a single extrusion opening of approximately 8mm the dough expanded by 50 to 100% and set. After drying for not less than half an hour using hot air of 50-70°C the extrudate was milled. Example II to XV The process of example I was repeated, using different compositions as summarized in table A. Evaluation The products as enlisted in table A were tested for hardness/crispness immediately after cooling down to room temperature using a trained test panel, distinguishing between H = hard and unacceptable, C = crisp, H/C = a bit in between but still just acceptable and T = tough. Also the products were tested for moisture resistance by equilibrating in environments of different relative humidity. After equilibration the moisture content of the product was determined and also the brittleness properties by determining the acoustic emission using a Locan® analyzer when fracturing the product and expressing this as a percentage of the acoustic emission when fracturing the freshly prepared product. The results of these tests are summarized in Table B. For both the panel test and the acoustic emission determination the particle size for the crumb was from 2.4 to 2.8mm. In this table the following expressions are used: CGL = commercial gluten (comprising 9% wheat starch 77%, protein, 6% lipid and 7% moisture) WMS = waxy maize starch (1% amylose + 90% amylopectin and about 10% moisture) WS = wheat starch (24% amylose, 67% amylopectin and 9% moisture) texture = texture defined by an experienced consumer testing group C = crisp H = hard C/H = partly crisp/partly hard T = tough RH = relative humidity % brittleness = measured by acoustic emission in % of the emission of the fresh prepared product at 0% relative humidity. Example COMPOSITION Pure Gluten Protein Amylose Amylopectin RATIO Amylopectin:Amylose CGL WMS WS XII 100 -- -- 77 2.1 6.0 2.9:1 XIII 80 20 -- 62 1.9 22.8 12.0:1 XIV 80 10 10 62 4.2 20.5 4.9:1 XV 80 -- 20 62 6.5 18.2 2.8:1 I 70 30 -- 54 1.77 31.2 17.6:1 II 70 15 15 54 5.24 27.8 5.3:1 III 70 -- 30 54 8.7 24.3 2.8:1 IV 60 40 -- 46 1.62 39.7 24.4:1 V 60 20 20 46 6.24 35.0 5.6:1 VI 60 -- 40 46 10.86 30.4 2.8:1 VII 40 60 -- 31 1.38 56.4 40.9:1 VIII 40 30 30 31 8.31 49.5 5.6:1 IX 40 -- 60 31 15.24 42.6 2.8:1 X -- 100 -- -- 0.9 90 100:1 XI -- -- 100 -- 24 67 2.8:1 Example ACOUSTIC EMISSION (%) MOISTURE CONTENT (%) TEXTURE AT 0% RH RH 0 33 57 69 75 0 33 57 69 58 XII 100 98 98 84 9 1.9 6.1 8.3 9.3 11.7 H XIII 100 -- 93 -- 3 2.6 -- 9.7 -- 12.4 C/H XIV 100 -- 30 -- 1 2.1 -- 9.7 -- 12.6 C/H XV 100 -- 48 -- 2 2.7 -- 10.1 -- 12.8 C/H I 100 80 84 52 1 1.6 8.2 9.7 10.4 12.5 C II 100 94 53 22 1 1.7 7.9 10.9 10.5 -- C III 100 64 9 1 0 1.6 9.1 10.8 11.5 -- C IV 100 87 80 43 1 1.5 7.9 9.7 10.8 11.5 C V 100 93 42 14 1 1.6 7.1 9.3 10.2 12.5 C VI 100 96 7 2 0 1.5 8.9 10.7 11.3 13.1 C VII 100 89 36 12 1 2.6 8.9 11.2 11.6 13.6 C VIII 100 -- 50 -- 3 3.1 -- 10.5 -- 12.8 C IX 100 70 10 5 1 2.6 8.6 10.8 11.0 13.1 C X 100 86 9 4 0 2.1 9.2 12.7 13.4 14.8 T XI 100 35 3 2 1 2.2 9.0 11.7 12.2 14.2 T

Claims: Crisp edible material predominantly comprising gluten and starch including amylopectin and amylose characterised in that the pure gluten protein content ranges from 62% to 46%, the total starch content is from 27.2% to 45.4% and the ratio of amylopectin to amylose ranges from 12:1 to 24.4:1. Material according to claim 1, characterised in that the material is expanded. A method of preparing an expanded food material comprising extruding a mixture mainly consisting of starch and gluten in the presence of water at elevated temperature, characterised in that predominantly 46 to 62% of pure gluten protein and 27.2 to 45.4% of starch having an amylopectin to amylose ratio ranging from 12:1 to 24.4:1 is mixed together with up to 30 parts water per 100 parts solids and extruded at a temperature between 100 and 150°C. The method of claim 3 characterised in that the mixture is extruded at a temperature between 120 and 140°C. The method of claim 3 or 4 characterised in that up to 20 parts water per 100 parts solids are used. The method of claim 3, 4 or 5, characterised in that the starch is predominantly waxy maize or waxy rice starch. The method of any one of claims 3 to 6, characterised in that the expanded material after extrusion is dried using a gas having a temperature not exceeding 70°C.

Inventors: DAVIES ALAN, HENDERSON JOHN ANDREW, INGMAN SIMON, DAVIES, ALAN, HENDERSON, JOHN ANDREW, INGMAN, SIMON, DAVIES, ALAN, UNILEVER RESEARCH COLWORTH LAB., INGMAN, SIMON, UNILEVER RESEARCH COLWORTH LAB.
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1993
Main classification: A23L1
IPC codes: A23J3, A23L1