EP1696740A1

EP1696740A1 - A process for chemically modifying protein containing food ingredients and such ingredients

Info

Publication number: EP1696740A1
Application number: EP05814249A
Authority: EP
Inventors: Andreas Muscat
Original assignee: Blattmann Cerestar AG
Current assignee: Blattmann Schweiz AG
Priority date: 2004-11-16
Filing date: 2005-11-03
Publication date: 2006-09-06
Also published as: WO2006053642A1; DE102004055312A1

Abstract

A vital protein containing base material, such as vital gluten, which can be used as a food additive, such as a baking ingredient, is chemically modified by a thermal treatment in the presence of an aroma enhancer, such as amino acids, saccharides, or polysaccharides, or hydrolyzed proteins, resulting in an improved aroma sensation for the prepared goods whilst maintaining the vitality of the proteins.

Description

A process for chemically modifying protein containing food ingredients and such ingredients

Field of the invention

The present invention is related to improvements for the food industry, by providing a method of chemically modifying food ingredients, which contain vital proteins such as vital gluten, leading to an improved aroma of the food whilst maintaining the vitality of the proteins. The aroma improved ingredients may be used in baking ingredients, as additive for confectionary fillings or coatings, or in thickening agents, such as a roux. The present invention also relates to the resulting food ingredients and their use in various food preparations.

Background

Proteins are widely used in food industry both as primary nutritious element such as presented by protein food products such as milk, eggs, cheese, meat, fish and certain vegetables as well as a food additive, such as to improve the nutritional value of the food or the physical or sensory properties thereof. Of particular importance are non-denaturized proteins, or so called vital proteins, for which vital gluten is a typical representative.

Modern food industry is highly dependent on consumer perception and taste and requires not only consistent quality independent of the naturally varying raw materials, but also an increasing flexibility and diversity in product formulation. Organoleptic properties such as the aroma should for example not only signal freshness of baking goods such as bread, but should also signal special baking compositions having particular additives (e.g. whole grains such as sun flower seeds) or aromas. Whilst bread is an important member in the family of baking articles, others such as cakes, waffles, buns, biscuits, crackers etc. aim for the same goals of long lasting freshness impression, suitable shape and volume, pleasant taste and aroma, ease of preparation and serving, health benefits etc. Generally, such articles are based on a starchy/protein component, a liquid compound and baking aids, e.g. flour, water, salt and yeast in the case of leavened dough or baking agents in the case of batters. Whilst the process should be consistent, and often continuous, yet remain flexible, it is subject to a lot of variations due to external factors (fermentation temperature and duration, baking temperature and duration, humidity, handling,...) and internal factors (quality and proportions of the ingredients). In order to ensure the mentioned consistent quality, "improvers" may be used, which of course need not only to satisfy health and regulatory requirements, but which should not deter conscious consumers aiming at "natural" products from purchasing the product (see EP-A-1080642).

A typical improver is vital gluten, which can further be modified such as described in US-patent 4076845, relating to dry powdery gluten which has been modified for improving the baking properties by reaction with a nontoxic chelating agent, for example, sodium citrate, EDTA, phytates, or phosphates. In EP-A-0282038, gluten is described to be modified by mixing wheat flour, L-ascorbic acid, cystine and water, then giving a mechanical damage to the resulting dough-like hydrated flour mixture.

Other developments aim at improving the organoleptic properties of baking goods, in particular the flavour or aroma properties. The German utility model DE-20314608U describes various coloured and/or aromatic flours and other additives, and/or natural and/or synthetic colour and/or aroma substances compatible with food regulations to be mixed into food products, such as dumplings or rolls. In EP-A-1206913, a flavoured bread improver composition is described comprising an emulsifier, an encapsulated matrix and a co-emulsifier consisting of a blend of aroma chemicals having co-emulsifier properties. Following the teachings of EP- A-1161883, a dough system for baking articles intended to be pre-baked by the producer and then crisped up by the consumer comprises at least flour, water, leavener, bread improver ingredients, and an encapsulated amphiphilic flavour to be released during or after the last baking step at the consumer. A mixture for intensifying the browning and aroma of baked goods is described in EP-A-0937402, which is spray-applied to the surface of pre-formed baking articles so as to enhance browning and aroma. The mixture comprises ascorbic acid (or salts thereof), amino acids (isolated or as hydrolyzed protein), C-₅-carbohydrates (isolated or as roasted malt), (oligo-) phosphates and optionally (salts of) lactic acid, or a saccharine material. DE-A-19544916 relates to exposing bread products or ingredients for the preparation thereof to smoke so as to alter the flavour and to extend the shelf life of the baked product. Buckwheat flour is known to be thermally treated to enhance - inter alia - aroma and flavour by mild caramelization, as shown in FR-A-2808420. From DD-217981 , a process for the production of protein hydrolysates is known, wherein, however, the vitality of the protein is lost due to the hydrolysis, thus making it unsuitable for baking purposes.

Apart from the baking industry, use of gluten or gluten containing ingredients in the food industry is well known in the context of changing physical properties, such as the rheological properties of aqueous liquids, such as confectionary fillings or coatings, sauce binder, or gravy thickener, or roux. In PCT application WO 03/61406 there is described the addition of gluten to a filling such as for confectionary items such as nutritional bars without impacting on the taste of the food item. In PCT application WO 99/046036, the use of gluten under acidic conditions as emulsification, gelling, or foaming agent is described. In US patent 5536533, the preparation of roux is described by caramelization of wheat gluten in the presence of soybean oil. However, all the above approaches do not fully resolve the desire for an enhanced aroma sensation, which is readily adjustable in intensity as well as in the type of aroma,, and which can be provided in an easy yet consistent type of application, which does not reduce the vitality of the ingredients.

Summary These desires are met by the present invention, which concerns in one aspect the chemical modification of a food ingredient containing vital proteins for an enhanced aroma sensation, and in a second aspect the materials as obtainable by such a process. In a particular embodiment it relates to chemically modified vital gluten as aroma carrier for food ingredients, in particular for baking ingredients.

Thus, the present invention is a method of chemically modifying a vital protein containing base material for a food ingredient, comprising the following steps: a) Providing a vital protein containing base material, which preferably exhibits a moisture of less than 40%, and which preferably comprises gluten as made from cereals, more preferably from wheat or spelt, and most preferably vital wheat gluten. It is further preferred, that this material contains more than about 50% protein on dry base. b) Providing an aroma enhancer capable of reacting with the vital protein base material at elevated temperatures, which is preferably selected from the group consisting of amino acids, polysaccharides, saccharides, or hydrolyzed proteins, or mixtures thereof. Preferably, the aroma enhancers are applied in a liquid form, and more preferably, they are in the form of an aqueous solution or emulsion. The aroma enhancers are preferably provided in amounts of at least 1% and typically not more than 50% by dry weight on the combined dry base of the protein containing base material and the aroma enhancer. c) Mixing the vital protein containing base material and the aroma enhancer in a mixing equipment. In a preferred embodiment, the mixing is achieved by spraying an aqueous solution or emulsion of the aroma enhancer. Preferably, the mixing is performed in a fluidized bed, or a rotary mixer. d) Thermally treating the mixture to initiate aroma ingredient creating chemical reaction, which can be of the covalent, ionic bonding, hydrogen bonding type, and which preferably is of the Maillard-reaction type. The treatment conditions should be at more than 60⁰C, can preferably be at more than 100⁰C, and are often preferred to be at more than 11O⁰C, but should be at less than 200⁰C, can preferably be at less than 180⁰C and are often preferred to be at less than 150⁰C. If desired, vacuum can be applied, which, however, should not be too strong as this might deteriorate the aroma intensity. The time for the thermal treatment should be at least 1 minute, can preferably be more than 10 minutes, and will often be preferred to be more than 15 minutes, but should be less than about 8 hours, can preferably be less than about 2 hours, and is often preferred to be less than about 60 minutes. The vital protein containing base material may comprise vital gluten, wherein the vitality of the gluten as can be determined by a Perten® Gluten Index and/or by the Bartender® Extensograph®. Preferably, the Gluten Index should be more than about 10 %, more preferably between 10 % and 80 %, and often a Gluten Index of between 30 % and 60 % will be most preferred. Applying the chemical modifications according to the present invention should not unduly change the Gluten Index so as to be outside these ranges. The "Extensograph area", should preferably not be reduced by more than 50% more preferably 25%, and most preferably essentially not at all, when comparing material prior to the mixing and after the thermal treatment. In the second aspect, the present invention is a vital protein containing food ingredient obtainable by the method as described, which exhibits a predetermined aroma effect, preferably selected from the group of nutty, fruity, meaty, spicy, or vegetable aroma sensation. The food ingredient can be used as baking ingredient, as filling or coating additive, or an emulsification, gelling, or foaming additive such as for modifying physical properties of viscous aqueous or oily food or food ingredients. In a further aspect, the present invention is a chemically modified vital gluten as aroma carrier for food ingredients and in particular for baking ingredients and premixes therefore, preferably exhibiting a Gluten Index of more than 10 %. When applying the Bartender® Extensiongraph® method, the area under the curve (corresponding to the energy required for the extension) should preferably be at least 50% of the area as established for an un-modified reference gluten material. Preferably the food such as the baking goods will exhibit an enhanced aroma sensation of the nutty, fruity, meaty, spicy, or vegetable type.

Detailed description

The present invention relates to the chemical modification of food ingredients containing vital protein for an improved aroma sensation.

Within the context of the present invention, the term "food ingredients" refers to any ingredient suitable for human diet, be it a primary nutritious element such as meat, fish, milk, cereals and the like, or be it an additive, such as seasoning, spices, sauces, and so on. In a particular aspect, the present invention relates to particular food additives, which may affect the physical properties of food elements, such as the strength or appearance of a dough, or thickness or viscosity of a sauce.

Within the context of the present invention, the term vital protein refers to proteins for which the native or original chemical structure is such that it can undergo certain changes (activity) under certain process conditions, such as moisture, temperature, pH, salt concentrations and so on. If these process conditions are maintained for a period, which is too prolonged, or at too elevated levels, the protein becomes "denaturized" or inactive. Whilst such vital proteins may be collagen, or whey proteins, a particularly useful vital protein is vital gluten, which is a mixture of naturally occurring proteins, in particular gliadin and glutenin. Vital gluten may be produced from a variety of cereals comprising vital gluten at lower levels, such as barley, buckwheat, oats, rye, semolina, or spelt, the most important source for vital gluten is wheat comprising relatively high amounts of vital gluten. Without wishing to be bound by theory, it is believed, that this property is linked to the visco-elasticity of hydrated gluten, which in turn is related to the high proportion in the polypeptide chain of glutamine and other amino acids with non-polar groups.

Within the context of the present invention, the term "aroma" relates to the olfactory sensation of smell and taste, and thus is a combined effect of aroma ingredients being received via the nose and during the eating / chewing of a tasty food. Aroma as such is subjective to the person sensing it, as well as to the circumstances under which these are sensed. Nonetheless, there is general agreement, that certain aromas are pleasant and others not. In addition, aromas can signal information to the individual, such as about content or type of the food. Thus, food producer, who aim at pleasing both sensual and psychological expectations of a user, also want to highlight composition and/or quality of their food by matching consumers aroma expectations. Whilst typically aromas are derived from natural sources, such as fragrances, spices, fruits and the like, modern food industry needs consistent quality and broad availability at reasonable cost, which is difficult to satisfy by naturally occurring materials. Henceforth the present invention provides a method for modifying vital protein containing materials, such as being functional food ingredients, such that the end user perceives an improved aroma sensation of the food. In a further aspect, the present invention is a chemically modified vital protein containing food ingredient, providing an improved aroma sensation to the user. Preferably, the food ingredient is part of the recipe for preparing the food, and the improved aroma sensation is an added benefit without the need for a further additive. The food ingredient may be used in various food preparation processes, and the vitality of the protein allows its use for baking, but also for cooking, e.g. when thickening a filling, a coating, a sauce, or a gravy or preparing a roux.

The present invention is particularly useful when being applied to baking ingredients, and thus the principles of the present invention will be explained in more detail by using this application area without intending any limitation to such an application. Within the context of the present description, the term "baking" refers to the process of preparing a mixture of baking ingredients, also referred to as dough or batter, and of exposing this to dry heat, generally in an oven, whereby the structure of dough or batter changes to the one of the baked goods. Without limiting the scope of the present invention, such "baked goods" may be bread, cakes, cookies, waffles, buns, pasta, biscuits, crackers.

The mixture of baking ingredients may undergo certain process steps prior to the heating step, such as in case of leavened doughs the rising of the dough to create gases (such as carbon dioxide) so as to provide a more porous structure of the dough and of the final baked goods.

During the period of the application of the dry heat in the baking process, which is often used synonymously for "baking", a number of physical and chemical processes take place. These generally thermally induced or initiated processes will not happen simultaneously and homogeneously throughout the structure. Most pronounced and visible will be such effects on the surface of the baked goods, where most of the browning will occur. However, the heating will induce structural modification throughout the total baked goods. In vital gluten containing dough, the heating will remove water molecules entrapped in the generally water insoluble protein (here gliadin and glutenin) containing ingredients by forming a network structure having elasticity and plasticity so as to allow entrapment of gas bubbles. The baking process is stopped, when the moisture removal resulted in optimum properties of the structure with regard to tactile properties, such as being crisp at the surface and soft in the centre. In order to achieve these properties, the gluten needs to be "vital" in contrast to being denaturized or devitalized, such as would occur by long lasting heat treatment, upon which the gluten will not contribute to any rising of the dough. Without wishing to be bound by theory, it is believed, that this property is linked to the visco-elasticity of hydrated gluten, which in turn is related to the high proportion in the polypeptide chain of glutamine and other amino acids with non-polar groups.

One of the most important chemical reactions during the baking process is the development of particular aromas and flavours, such as by caramelization, and a key reaction type is generally known as Maillard reaction.

Commercial baking is frequently done in a continuous process of mixing, panning, rising, and baking of dough. It will be appreciated, that the baking process as such is quite complex, and the result will often be a compromise across the various requirements on the consumer side, such as mainly taste and appearance, and often conflicting requirements on the baker's side, such as ease or cost of production. One approach to provide more flexibility is the preparation of premixes of certain ingredients and/or additives for any of the required steps, most frequently being dry mixes of ingredients, although premixed pastes are also used. These carry the advantage of ease of application, such as eliminating separate weighing steps. A further approach is the "pre-baking", where consumers buy pre- baked articles and finish the baking under well defined conditions at their home, so as to have freshly baked goods. Out of the above mentioned "baking ingredients", the most important ingredient for baking goods are based on cereals, such as wheat, barley, rye, corn, rice, spelt, etc., in the form of whole grains, ground or milled grains, flour, etc. It may further comprise modified cereal materials, such as being hydrolysed, or extracts form cereals, such as gluten which is naturally occurring at different levels in various cereals. These materials also provide the sticking properties which hold the baking goods together.

Water is added to the baking ingredients so as to provide the appropriate dough structure, i.e. the right rheological properties. Yeast or baking agents create a porous structure by releasing carbon dioxide in the form of small gas bubbles entrapped in the dough. Salt is generally used not only for taste, but also to improve the physical dough properties. Further, there exists a plethora of other additives, often referred to as "improvers". Without limitation, such improvers may be oxidizers, such as azodicarbonamide, bromate, iodate; anti-oxidizers, such as ascorbic acid; reducers, such as cysteine, cystine, glutathione; enzymes, such as amylases, hemicellulases (pentosanases, cellulases, pectinases), lipases, galactomanases, oxidoreductases, glucoseoxidases; emulsifiers, such as diacetyl tartaric acid esters of monoglycerides (DATEM), sodium or calcium stearyl lactylates (SSL, CSL), mono- and diglycerides, polysorbates, lecithin; carbohydrates, such as saccharose, glucose, fructose, lactose, dextrine, maltodextrine; malt-ingredients, such as active malt flour, toasted malt flour, malt extract; starch, such as wheat starch, corn starch, potato starch; soy-derived products, such as soy flour, soy proteins, soy grits; thickeners and hydrocolloids, such as guarflour, locust bean gum, carboxymethyl cellulose, xanthan, alginates, etc.; milk-derived products, such as full fat milk powder, nonfat milk powder, lactoserum, whey powder, casein; vegetable and animal fats; salts, such as acetates, citrates, carbonates, sulphates, phosphates; preservatives, such as sodium di-acetate or salts of propionic or sorbic acid.

Also, proteins of protein containing materials can be added, in particular also gluten as such in order to improve dough properties.

The present invention aims at an improvement for the food industry by providing an easy way for improving the aroma sensation of the produced goods, such as of baked goods.

In contrast to many approaches for enhancing the aroma sensation for baking articles, the present invention separates the creation of flavours from the baking process as such. Because of the complexity of the baking processes, it is presently often the case, that other baking parameter like consistency, shape, volume or crispness of the baked article determine the baking process, thereby not providing optimal conditions for the aroma to develop its full potential. This applies also to the case, when aroma additives are used, even if these are specially treated such as being encapsulated. Further, the aroma additives are often added in relatively small quantities, and hence it may be difficult to mixed these homogeneously into the dough or batter.

This becomes even more pronounced, if a particular type of aroma is desired, which is not typically occurring as a result of the baking process. Examples of such aroma types are nutty, fruity, meaty, spicy, or vegetable flavours.

Henceforth, it is an important element of the present invention to create aroma delivering substances independent from the final baking process in the oven. Thus, substances are selected, which are able to enhance the aroma sensation, and which are capable of forming chemical bonds with a protein containing base material as a baking ingredient.

Whilst there exists a very wide array of such substances, these substances must be compatible with the requirements generally set up for foodstuff, and preferably with regulatory requirements for foodstuff, such as the US FDA requirements, or the Schweizer Lebensmittelverordnung etc..

Particularly suitable aroma enhancers are, without limitation, saccharides, such as mono-, di-, oligo-, or poly-saccharides, such as saccharose, starch, maltodextrine, inverted fluid sugar and inverted sugar-syrup, glucosesyrup, glucose-fructosesyrup, and fructose-glucosesyrup, dried glucosesyrup, dried glucose-fructosesyrup, dried fructose-glucosesyrup, dextrose, fructose, lactose, maltose, gelating sugar, vanillin sugar, vanilla- sugar, caramel sugar, burned sugar, hydrolysates such as from degradated polysaccharides and molasses of sugar beets or sugar cane.

Also very suitable aroma enhancers are amino acids, such as L-arginine and resp. hydrochlorides, L-cystine and resp. hydrochlorides, L-histidine and resp. hydrochlorides, L-isoleucine and resp. hydrochlorides, L-leucine and resp. hydrochlorides, L-lysine and resp. hydrochlorides, L-cysteine and resp. hydrochlorides, L-methionine, L-phenylalanine, L-threonine, L- tryptophane, L-tyrosine, L-valine, L-carnitine and resp. hydrochlorides, taurine, cytidin-5'-monophosphate and resp. sodium salts, uridin-5'- monophosphate and resp. sodium salts, adenosin-δ'-monophosphate and resp. sodium salts, guanosin-5'-monophosphate and resp. sodium salts, inosin-5'-monophosphate and resp. sodium salts and also protein hydrolysates e.g. from yeast or molasses.

In order to enhance Maillard-type reactions or to provide a catalyzing function further additives such as vitamins and minerals may be added to the enhancers, of course under the proviso, that these ingredients also satisfy the requirements generally set up for foodstuff, and preferably also the regulatory requirements for foodstuff, such as the US FDA requirements, or the Schweizer Lebensmittelverordnung etc..

In order to create a desired aroma sensation, one or several of these ingredients may be combined in various ratios. For example, in order to arrive at a nutty flavour, dextrine, dextrose, saccharose, and L-cystein hydrochloric monohydrate may be used. In order to arrive at a meat flavour, dextrose, saccharose, L-cystine, L-methionine, taurine and L- cystein hydrochloric monohydrate may be used. In order to arrive at a vegetable flavour, dextrine, dextrose, saccharose, L-lysine and L- aspargine may be used. The ingredients can be put together to create the aroma enhancer in various forms. When a dry mixing is performed, care should be taken that good mixing is ensured, and differences in density or particle size should be considered. A preferred execution relates to a liquid application, more preferably to the ingredients being dissolved, emulsified, or dispersed in water, thereby even further enhancing ease of application. Whilst strongly dependent on the particular ingredients, typical concentrations for the totals of aroma enhancer ingredients in the aroma ingredient solution (which encompasses in the present context also emulsions and dispersions) are more than about 1 % by dry weight and mostly less than 50% by dry weight of the total solution. The solution can be prepared at moderately increased temperatures, which should, however, not exceed 95°C. The aroma enhancer ingredients can then be applied to a vital protein containing base material. This can be any vital protein containing material, which is compatible with the baking process, and with food requirements. Preferably, the vital protein containing base material has a protein content of at least 50% by weight, on a dry basis, as can be determined by the method for "Determination of Protein by Near Infrared Reflectance (NIR) Spectroscopy", as issued be the International Association for Cereal Science and Technology (ICC, Vienna), as ICC Standard No. 159. It is further preferred, that the protein containing base material is an ingredient which is used in the baking process for other purposes. Thus it can be the total of the flour used for the baking, or it can be a portion of the flour, which is treated with the aroma enhancers. It can be also any protein containing "baking improver" such as described hereinabove. Particularly preferred protein containing baking ingredients contain proteins from cereals, such as glutens, milk proteins such as caseins, and more preferred is gluten, such as can be produced in known processes from cereals, such as wheat, rye, barley, or spelt. The protein containing base material is not necessarily but often in a dry form, having a moisture content of less than 40% by weight, as can be determined by conventional vacuum supported drying at 105⁰C for 3 hrs.

The combination of the aroma enhancing ingredients with the protein containing ingredients can be performed in conventional mixing equipment provided it allows even distribution. As the protein containing ingredient is generally in an excess amount, it is mostly better to add the aroma enhancing ingredients thereto. This can be done in a continuous process or in batch process. Without limitation, the protein containing ingredient can form a fluidized bed, to which the aroma enhancer can be added, possibly in a dry form but preferably in liquid form as a fine spray. The equipment can also be rotary mixer, such as of the so called Lόdige type or extruder mixer. If water is used as carrier for the aroma ingredients, care should be taken, that it is not added too quickly or too localized so as to avoid lumping or stickiness. Typically, per one part of protein containing ingredient, 0.01 to 1.0 parts of aroma ingredient solution can be applied. Also during this step, the temperature should preferably not exceed 95°C.

The mixture of the aroma enhancing ingredients with the protein containing material is then subjected to a thermal treatment at elevated temperatures so as to allow chemical reaction between the two materials. The treatment conditions should be at more than 60⁰C, can preferably be at more than 100⁰C, and are often preferred to be at more than 110⁰C, but should be at less than 200⁰C, can preferably be at less than 18O⁰C and are often preferred to be at less than 15O⁰C. If desired, vacuum can be applied, which, however, should not be too strong as this might deteriorate the aroma intensity. The time for the thermal treatment should be at least 1 minute, can preferably be more than 10 minutes, and will often be preferred to be more than 15 minutes, but should be less than about 8 hours, can preferably be less than about 2 hours, and is often preferred to be less than about 60 minutes. The required conditions will depend on the desired aroma, and it will be a regular experimental effort to optimize the conditions for the various mixtures.

The thermal treatment can be performed in a similar equipment as described for the mixing hereinabove, optionally the equipment for the two steps can be the same. In a particularly preferred execution of the process one reactor of the Noredux type, as known from Blattmann Cerestar, Switzerland, is used.

The chemical reaction taking place between the vital protein and the aroma enhancer is important, which can be of the covalent, ionic bonding, hydrogen bonding type. An important type of reaction is of the so called "Maillard-type" well known as such to a skilled person. Maillard reactions are generally referred to when a carbonyl group of a reducing sugar (aldose) reacts with a free amino group of a protein or an amino acid and leads to very complex reaction products, often exhibiting intensive smells. The resulting material will exhibit a particular odour, generally without a significant change in other properties of the vital protein containing base material. In the following, this is - without intending any limitation to the invention - further explained and exemplified in the context of vital gluten as protein containing base. In particular, if the protein containing base material comprises vital gluten, this vitality is at least to a large extent maintained during the described treatment. Thus, the aromatized protein containing baking ingredient can be used in conventional baking processes neither without significant changes thereof, nor of the properties of the resulting baking product except that it carries - or develops even further - the aroma.

The application to food ingredients other than baking ingredients can essentially be the addition of the aroma modified ingredient to foodstuff, where e.g. the use of gluten is beneficial for its physical properties or at least not detrimental thereto. Such physical properties can be rheological properties of viscous food, such as viscosity or flow behaviour of aqueous or oil based liquids or pastes. Thus, it can be used for cooking, e.g. when thickening a sauce or gravy or preparing a roux, or for confectionary fillings or coatings. For example, the aroma enhancement may allow to replace - at least partially - nuts in such fillings.

The vitality of gluten can be assessed by various test methods, such as published by the International Association for Cereal Science and Technology (ICC, Vienna). The reduction of gluten vitality through a process respectively the absence of such a reduction, can be determined by any of the^' these tests, wherein generally a bread is prepared and baked under standard conditions. For example, the volume of bread loafs can be measured via putting each loaf into a defined volume tester and measuring rape seeds needed to fill the empty space of the defined volume. The loaf volume can be determined via recalculation.

A very useful method standardized by ICC to determine the gluten strength and vitality is ICC-standard No.114, determining the water absorption as well as the extension properties of dough via area measurement by using a standardized equipment as the Brabender® Extensograph® as available by Brabender OHG, Germany. After standardized preparation of a dough, it is stretched until rupture in the Extensograph®. The force exerted is measured and recorded. Upon evaluation of the graphs, the Extensogram area before and after the treatment according to the present invention will be reduced by less than 50%, more preferably by less than 25%, and most preferably will show no significant reduction in the area.

A further useful test method relates to the determination of the Gluten Index, as described in ICC standard No 155 (wheat flour) and No 158 (wheat whole meal). If the material to be evaluated is whole grain, this should be ground, such as by using a laboratory hammer type mill. Gluten separated from whole wheat meal or wheat flour by the Glutomatic® equipment, or equivalent, such as the Glutomatic® 2015 as commercially available from Perten® Instruments, AB, Sweden, is centrifuged to force wet gluten through a specially constructed sieve under standardized conditions. The total weight of the gluten is defined as gluten quantity. The percentage of wet gluten remaining on the sieve after centrifugation is defined as the Gluten Index. If the gluten is very weak (or exhibits a very low vitality), all of the gluten may pass through the sieve, and the Gluten Index is 0; for extremely strong gluten, where nothing passes through the sieve, the Index is 100. Preferably, the Gluten Index should be more than about 10 %, more preferably between 10 % and 80 %, and often a Gluten Index of between 30 % and 60 % will be most preferred. Applying the chemical modifications according to the present invention should not change the Gluten Index to be outside these ranges. The Gluten Index in combination with the Extensograph® describes the vitality of a gluten type very well. Whilst these tests have been described in the context of specific type of flour (triticum aestivum), the skilled person will readily apply the principles to other types.

In addition, further ICC methods, such as ICC method No.115

(Brabender® Farinograph®), determining the water absorption as well as the consistency, i.e. the torque when dough is mixed under constant speed), or ICC method No. 121 (using the Alveograph® to determine the resistance of the dough to stretching and its extensibility) can be used to determine dough properties.

Example 1

A solution was made with following composition (table 1) at a temperature of 62°C.

Table 1

This solution was sprayed as a fine spray at 50°C with a valve speed of 2.5 litre per hour on 1000 g of gluten and mixed for about 10 minutes in a Lόdige 5 litre size mixer.

300 grams of each preparation were heated under a vacuum (97 mbar) to remove the condensate water preventing gelation of the starch in a Rotavapor type Bϋrchi RE 111 at 11O⁰C up to 150° C for about 15 to 60 minutes according to temperature program of the Rotavapor at a speed of 5°C / min until 60⁰C are reached, followed by a 1 minute holding period, then at 2.5 °C/min until the end temperature was reached. The thermal treatment times at final temperature at the respective temperatures are shown in table 2.

Table 2

Each of the four preparations has been assessed by sensory evaluation, whereby each showed a different intensity of smell, similar to breadcrumb, nuts or toasted bread.

Example of bread preparation

Four different breads with modified taste by using the four gluten- preparations, according to Table 2, were prepared. The composition is set forth in Table 3, where each component is indicated as a percentage of the total wheat flour (percentage on a total flour basis). The dry components were followed by the water with a temperature of about 25°C.

Table 3

These compositions were placed in a Herbst mixer with a bowl attachment and mixed for 10 minutes. The dough was placed in a plastic bowl and allowed to rest for 70 minutes at room conditions. 500 grams of dough were separated and placed in a 0.9 litre aluminium bakery form. The raw bread was baked in an electric oven (WTB Binder) at 21O⁰C for 40 minutes.

A comparative bread (Sample 5) was made with 2 % of commercially available vital wheat gluten (VWG) instead of the aroma modified gluten. Six hours after the baking process the breads were compared for their volume, and each bread was cut through the middle and evaluated. The results are summarized in Table 4.

Table 4

Henceforth, the modified gluten samples exhibited improved sensory properties without negative impact on other properties as the volume.

Claims

1. Method of chemically modifying a vital protein containing base material for a food ingredient, comprising the steps of a) - providing a vital protein containing base material; b) - providing an aroma enhancer capable of reacting with said vital protein base material at elevated temperatures; c) - mixing said vital protein containing base material and said aroma enhancer in a mixing equipment; d) - thermally treating said mixture for more than 1 minute, but less than 8 hours at more than 6O⁰C and but less than 200°C to initiate an aroma creating chemical reaction.

2. Method of chemically modifying a vital protein containing base material according to claim 1 , wherein said vital protein containing base material comprises vital gluten, preferably from cereals, more preferably from wheat or spelt.

3. Method of chemically modifying a vital protein containing base material according to any of claims 1 or 2, wherein said vital protein containing base material has a moisture content of less than 40% by weight.

4. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 3, wherein said vital protein containing base material comprises at least 50% by dry weight of protein.

5. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 4, wherein said aroma enhancer is selected from the group consisting of amino acids, polysaccharides, saccharides, or hydrolyzed proteins, or mixtures thereof.

6. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 5, wherein said aroma enhancer is added at a level of more than 1% on a dry weight basis of said vital protein containing base material and said aroma enhancer.

7. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 6, wherein said aroma enhancer is in liquid form, preferably an aqueous solution or emulsion.

8. Method of chemically modifying a vital protein containing base material according to claim 7, wherein said aroma enhancer is applied in liquid form at a concentration of at least 1 % on the weight basis of said vital protein material and liquid carrier.

9. Method of chemically modifying a vital protein containing base material according to any of claims 7 or 8, wherein said aroma enhancer in liquid form is sprayed onto the vital protein containing base material.

10. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 9, wherein said mixing is performed in a fluidized bed or a rotary mixer.

11. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 10, wherein said thermal treatment is performed for more than 15 minutes, preferably less than 2 hours.

12. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 11 , wherein said thermal treatment is performed at temperatures of more than 100⁰C, preferably more than 110⁰C.

13. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 12, wherein said thermal treatment is performed at temperatures of less than 180⁰C.

14. Method of chemically modifying a vital protein containing base material according to claim 13, wherein said thermal treatment is performed at temperatures of less 150⁰C.

15. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 14, wherein said aroma creating chemical reaction is of covalent, ionic, or hydrogen bonding type.

16. Method of chemically modifying a vital protein containing base material according to any of claims 1 to 15, wherein said aroma creating chemical reaction is of the Maillard-type.

17. Vital protein containing food ingredient obtainable by a method according to any of the preceding claims.

18. Vital protein containing food ingredient obtainable by a method according to claim 17 exhibiting a predetermined aroma effect, preferably selected from the group of the nutty, fruity, meaty, spicy, or vegetable aroma type.

19. Vital protein containing food ingredient according to claims 17 or 18 for use as baking ingredient or in a baking premix.

20. Vital protein containing food ingredient according to claims 17 or 18 for being used to adjust rheological properties of viscous food, preferably for being used in gravy thickening or for a roux or confectionary filling or coatings.