FIELD OF THE INVENTION

The present invention relates to a method for converting faba beans to nutritionally valuable ingredients, where faba beans are subjected to fractionation by air classification, followed by fermentation. The present invention also relates to nutritionally valuable faba bean ingredients as well as to their use in foodstuffs and animal feeds.

BACKGROUND OF THE INVENTION

There is a growing need to decrease the consumption of animal based proteins and to increase the availability of plant based proteins. Legumes, such as beans provide cheap and nutritious foods as they comprise high amounts of proteins. Faba beans may typically contain about 35-38 wt% of proteins. On the other hand faba beans also contain antinutritional factors (ANFs), which may have negative effect on the health of the individual consuming faba beans. Examples of said ANFs are tannins, lectins, trypsin inhitors, phytic acid and toxic vicine and convicine, which may cause a disease called favism, a severe hemolytic anemia. These ANFs limit the use of faba beans in foods and animal feeds.

Various methods have been suggested for the removal of ANFs, such as germination, extrusion cooking, autoclaving and toasting. Further, McKay A M, ] Appl. Bact. 1992, 72, 475-478, describes partial reduction of vicine and convicine in faba beans by growth of Lactobacillus plantarum on faba bean suspensions.

The western diet is commonly based on wheat and other gluten containing cereals. Wheat is not very nutritious and it typically comprises mainly simple carbohydrates, very little vitamins and minerals. Wheat and also other cereals and grains comprise gluten, which is a protein formed of gliadin and glutenin. The consumption of gluten may cause adverse effects in part of human population. Celiac disease is an autoimmune intolerance to gluten, resulting in the degradation of the intestinal villi and decrease in macro- and micro-nutrient absorption. A variety of symptoms, such as diarrhea, bloating, weight loss, skin rashes, spontaneous abortions etc. may occur as a result of gluten consumption. There is also a clear link between celiac disease and diabetes I and II.

The only treatment for celiac disease is life-long gluten-free diet. The amount of gluten- free products on the market increases constantly. In many cases gluten-free products are made of a single ingredient, such as rice or maize. These starch based products have much higher GI than wheat products. There are also other commercially available gluten-free products based on soy, peas, buckwheat etc. having characteristic organoleptic and rheological properties.

The speed at which carbohydrates are absorbed is expressed by the glycemic index (GI) : the higher the index is, the faster the carbohydrate absorption results and consequently insulin absorption. In the long run, this affects the insulin production process and leads to diabetes onset. Glucose has GI of 100.

Despite the ongoing research and development there is a need for a method for reducing ANFs in faba beans and provide a nutritionally valuable faba bean ingredients, suitable in foods and animal feeds.

SUMMARY OF THE INVENTION

An object of the invention is to provide a method for converting faba beans to a nutritionally valuable ingredients.

A further object of the invention is to provide new nutritionally valuable faba bean ingredients. Another object of the invention is to provide uses of the nutritionally valuable faba bean ingredients in food and animal feeds.

Thus the present invention relates to a method for converting faba beans to nutritionally valuable ingredients, where the method comprises the steps of grinding faba beans, subjecting the ground faba beans to fractionation by air classification to obtain at least two fractions, followed by fermentation of at least one fraction.

The present invention also relates to new nutritionally valuable faba bean ingredients, having decreased ANF content. The present invention also relates to new nutritionally valuable faba bean ingredients, having decreased ANF content and high protein content.

The present invention also relates to new nutritionally valuable gluten-free faba bean ingredients, having decreased ANF content.

The present invention also relates to new nutritionally valuable gluten-free faba bean ingredients, having decreased ANF content and high protein content.

The present invention also relates to uses of the nutritionally valuable faba bean ingredients in food and animal feeds.

The present invention also relates to a method for the manufacture of bread from the fab bean ingredient. Characteristic features of the invention are presented in the appended claims. DEFINITIONS

The term "ANF" refers here to anti-nutritional factors present in unprocessed faba beans, including tannins, lectins, trypsin inhitors, phytic acid, vicine, and convicine.

The term "gluten-free" means here that a product contains not more than 20 ppm of gluten.

DETAILED DESCRIPTION OF THE INVENTION

It was surprisingly found that ANFs of faba beans can be decreased to low levels, and simultaneously the amino acid profile of faba beans can be modified to more favorable amino acid profile for human food and animal feeds, with a method which comprises the steps of grinding faba beans, subjecting the ground faba beans to fractionation by air classification to obtain at least two fractions, followed by fermentation of at least one fraction.

Faba beans, also known as broad beans and horse beans, are understood to mean here beans belonging to the species Vicia faba L. Several sub-species have been developed, typically adapted to local weather conditions, such as Aurora, Divine, Kontu, Jogeva, Maya, Ukko etc. Faba bean is an important protein source particularly in human food in developing countries and as animal feed for pigs, horses, poultry and pigeons in industrialized countries. The protein content in faba beans may vary between 20 and 41 wt%, depending on both genetic and environmental factors.

Faba beans contain no gluten, which makes them suitable for population suffering from celiac disease or other forms of gluten intolerance. In the case of celiac disease the only form of therapy is lifelong avoidance of gluten or gluten proteins.

In the method of the invention dehulled faba beans are used as starting material. The dehulling may be carried out using any suitable dehulling method known in the field. Grinding

The faba beans (dehulled faba beans) are subjected to grinding to obtain ground faba beans. The grinding may be carried out by using any suitable grinding, milling, or pulverizing equipment, preferably using impact milling. Suitable milling devices are for example pin disc mills and the like. The grinding may be carried out for at least one pass, suitably from 1 to 3 passes. The grinding temperature can be between G-8G°C, through put 5-300 kg/h (depending on the machine) at atmospheric pressure.

In the manufacture of products in the examples the grinding was carried out by a 100UPZ pin disc mill (Hosokawa Alpine AG, Germany), with two grinding steps with the maximal speed 17800 rpm. However, similar result can be obtained with other types of mills, for example with pin disc mills equipped with two different motors, whereby one grinding step would give similar particle size distribution.

The grinding parameters are adjusted to provide ground material having desired average particle size or close to it.

In an embodiment of the invention the average particle size of the ground faba bean material after the milling is suitably about D50 = 20-100 μιη and D90 =50- 150 μιη. Fractionation by air classification

The ground faba bean material is subjected to fractionation by air classification in an air classifier or air separator where the material stream is injected into a chamber which contains a column of rising air. Inside the separation chamber, air drag on the objects supplies an upward force which counteracts the force of gravity and lifts the material to be sorted up. The materials are separated by a combination of size, shape and density. The air classification of the ground faba bean material is carried out to provide at least a coarse fraction and a fine fraction.

The coarse fraction has suitably average particle size of about D50 = 20-100 μιη and D90 = 40-150 μιη, preferably D50 = 20 - 80 μιη and D90 = 70 - 150 μιη, more preferably D50 = 20 - 30 μιη and D90 = 45 - 85 μιη, still more preferably D50 = 25 - 30 μιη and D90 = 70 - 80 μιη.

The protein content in the coarse fraction is suitably 10-35 wt%, preferably 20-25 wt%. The yield of the coarse fraction is typically 56-68 wt%. The coarse fraction is starch rich, typically it comprises from to 35-50 wt%, preferably 40-45 wt% of starch. In the air classification the content of vicine and convicine in the coarse fraction is reduced by even 68 wt%.

The fine fraction has average particle size of about D50 = 12-50 μιη and D90 = 30-85 μιη, preferably D50 = 12-25 μιη and D90 = 30-55 μιη.

The protein content in the fine fraction is suitably 59-73 wt%. The yield of the fine fraction is typically 32-44%. Higher protein content results in lower yield. Starch content in the fine fraction is typically less than 35wt%. The ANFs, particularly tannins, lectins, trypsin inhitors, phytic acid, vicine, and convicine are predominantly located in the fine fraction.

Fermentation

The coarse fraction is fermented to obtain high starch gluten-free faba bean ingredient and the fine fraction is fermented to obtain high protein gluten-free faba bean ingredient.

In the fermentation the fraction (fine or coarse) is mixed with water and the fermentation is carried out with a lactic acid bacteria. This mixture is called here fermentation dough.

Suitably the fraction is mixed with water in a ratio of about 30-50 : 50-70, preferably about 50 : 50. The starter used in the fermentation is lactic acid bacteria, suitably said lactic acid bacteria strain is selected from Lactobacillus plantarum, Lactobacillus brevis and Lactobacillus pentosus. Preferably lactic acid bacteria strains possessing beta- glucosidase activity and GAD activity are used.

The fermentation with the selected starter is carried out at a temperature of 24-37°C, suitably for 20- 60 hours, preferably for 30-50 hours.

Suitably the initial cell density in the fermentation dough is about 10 ⁷ CFU/g. The initial pH is suitably 6.6-6.8.

After fermentation (for example about 48 hours), the cell density of lactic acid bacteria typically ranges from 2.0 to 2.5 xlO ⁹ CFU/g. The pH values range from 4.1 to 4.6.

Acidity values typically vary after fermentation in the dough from 19 to 34 ml of 0.1 M NaOH. Lactic acid is the predominant acid, varying from 103 to 130 mmol/kg of dough, while acetic acid ranges typically from 9 to 21 mmol/kg of the dough.

In the method the amino acid profile of faba beans is modified, particularly the content of essential amino acids is increased, the most significant increased being for threonine, cysteine, valine, methionine, isoleucine, leucine, phenylalanine, histidine, tryptophan, and lysine; and for non-essential amino acid tyrosine. The total amount of free amino acids can be increased by 126% calculated by weight.

Further, the content of γ-aminobutyric acid (GABA) was increased even 44 wt%. GABA is a well-known important nutritional factor, and various scientific studies have been carried out to reveal its effects. GABA is a four-carbon non-protein amino acid, and it acts as the major inhibitory neurotransmitter of the central nervous system. Other physiological functions of GABA are induction of anti-hypertensive, prevention of diabetes, diuretic and tranquilizer effects. For example, the daily intake of 10 mg of GABA for 12 weeks is sufficient to decrease blood pressure by 17.4 Hg in hypertensive human patients. As the consequence, GABA is extensively used in pharmaceutical preparations and functional foods, such as gammalone, dairy products, gabaron tea and shochu. The fermented fractions, particularly the fermented fine fractions obtained according to the method of the Invention have a GABA content varying from 1030 to 1230 mg/kg of GABA.

In the method the coarse fraction is fermented, and the fine fraction is fermented, each separately to yield a fermented coarse fraction and a fermented fine fraction. The fermentation may be carried out in separate vessels or successively in the same vessel.

After fermentation of the coarse fraction the level of ANFs, particularly vicine and convicine can be reduced by 82% and 31 wt% (24 h fermentation) and 90% and 55% respectively (48 h). The reduction level of trypsin inhibitor was 100%, tannins 24% and phytic acid 9%.

After fermentation of the fine fraction the level of ANFs, particularly vicine and convicine can be reduced by 93% and 44 wt% (2.4 h fermentation) and 95% and 91% respectively (48 h). The reduction level of trypsin inhibitor was 87%, tannins 52% and phytic acid 36%.

Further, it was observed that the fermented fractions have reduced in-vitro starch hydrolysis index and lower glycemic index (GI) .

The fermented fractions are obtained in the form of dough (fermented dough, comprising the fermentation mixture). Optionally the dough may be subjected to drying and optional grinding to obtain flour. The drying may be carried out using methods known in the field, suitably at the temperature of 0-80°C. The dried product may be packed and stored and used later as an ingredient for the manufacture of food products and animal feeds. The dough may also be used directly without drying for the manufacture of food products and animal feeds.

Faba bean ingredient

The faba bean ingredient is obtainable by the method of the invention. The faba bean ingredient comprises the fermented fine fraction or the fermented coarse fraction or a combination thereof. The faba bean ingredient comprises not more than 60 wt% of water, preferably 30-60 wt% of water (in dough), or not more than 5 wt% (0.1-2 wt%) of water (in dried product). It comprises at least 40 wt% of the fermented fine fraction or the fermented coarse fraction or a combination thereof. It is gluten-free. According to one embodiment the protein content of the fermented coarse fraction is suitably 15-30 wt%, preferably 20-25 wt% and the starch content is suitably 60-70 wt%, preferably 50-60 wt%, calculated on dry matter. This is called here starch rich faba bean ingredient. According to another embodiment the protein content of the fermented fine fraction is suitably 50-80 wt%, preferably 59-73 wt%, calculated on dry matter. This is called here protein rich faba bean ingredient.

The fermented fractions, particularly the fermented fine fractions obtained according to the method of the invention have a GABA content varying from 1030 to 1230 mg/kg of GABA.

Use of faba bean ingredient

The fermented fractions (faba bean ingredients) may be used for the manufacture of food products and animal feeds, particularly for replacing cereal or grain products in food manufacture and in the manufacture of animal feeds.

Faba bean ingredients may be used for replacing for example flour partly or totally, such as semolina (wheat), soy, barley, rye and oat flours in food manufacture, particularly in the manufacture of protein ingredients, protein concentrates, vegetarian protein sources, meat analogs, cheese analogs, bakery products, such as bread, cakes, pizza, pastry products, confectionery products, and the like, pasta products, snacks, such as extruded snacks, puffed snacks, breakfast cereals, such as extruded cereals, puffed cereals and the like.

Preferably the protein rich ingredient is used for providing high protein products. Protein rich products and gluten-free products may be produced, having improved nutritional properties, where at least 20 % of the energy value of the food is provided by protein. The fermented fractions (faba bean ingredients) may also be used for the manufacture of animal feeds, such as granules, pellets etc.

The fermented fractions (faba bean ingredients) may easily be processed using conventional food and animal feed processing methods, such as extrusion etc, Unprocessed faba beans contain ANFs that can lower the nutritional value of faba bean products or in some cases have even more severe effects. Combined air classification and fermentation with lactic acid bacteria not only reduces the ANFs but also increases the amount of essential amino acids and gamma-a minobutyric acid (GABA), a nonprotein amino acid, possessing well-known physiological functions such as neurotransmission, induction of hypotension, diuretic and tranquilizer.

For example high protein bread and pasta can be produced from the faba bean ingredients obtained according to the method of the invention, and said products may be gluten-free and have low GI, depending on the optional ingredients used in their manufacture.

Method for the manufacture of a bread product

The invention also relates to a method for the manufacture of a bread product, comprising the steps where a mixture is formed of 50-70 wt% of protein rich faba bean ingredient, 30-50 wt% of a starch source and 1-6 wt% of sugar source calculated on total flour weight, leavening agent, 0-0.8 wt% of salt, 0-1 wt% of a gelling agent, 0- 05 wt% of an emulsifier, and 0 - 50 wt% of water, calculated from the total weight of the mixture, the mixture is agitated to form a composition, and baking the composition to bread. The amounts of protein rich faba bean ingredient and starch source are calculated on dry basis.

Particularly the mixture is formed of a) 50-70 wt% of protein rich faba bean ingredient comprising 50-80 wt% of proteins and not more than 60 wt% of water, 30-50 wt% of a starch source and 1-6 wt% of sugar source, where the amounts are calculated on total flour weight; and b) of leavening agent, 0-0.8 wt% of salt, 0-1 wt% of a gelling agent, 0-0.5 wt% of an emulsifier, and 0 - 50 wt% of water, calculated from the total weight of the mixture. In the case the water content of the protein rich faba bean ingredient is too low for baking, water may be added to the mixture. The baking is carried out with baking methods known as such.

The total flour weight refers here to the total weight of flours and faba bean ingredients.

Part of the protein rich faba bean ingredient, suitably 30-50 wt% of the protein rich faba bean ingredient may be replaced with one or more of other flour or ground nuts, said other flour being selected from wheat, rye, barley buckwheat, oat, corn, rice, quinoa, millet and the like. In the case gluten-free products are manufactured only gluten-free flours are used. Thus the protein rich faba bean ingredient may additionally comprise one or more of other flour or ground nuts.

The starch source is selected from maize starch, starch rich faba bean ingredient, rice starch, quinoa starch, millet starch, oat starch, potato starch and barley starch.

The leavening agent (raising agent) means one or more of yeast, sodium bicarbonate (baking soda), baking powder, and bacteria used for leavening. The leavening agent may be used in amounts of 1-6 % calculated from flour weight. If yeast or bacteria is used the composition is fermented at a temperature from 20 to 38°C.

The sugar source means here sugar, sucrose, syrup, honey, fruit juices and the like.

The gelling agent means here guar gum, agar agar, xanthan gum, locust bean gum, gum acacia, xanthan gum, gum Arabic, tara gum, hydroxypropylmethyl cellulose, psyllium fiber and gelatin.

The emulsifier may be an emulsifier used as additive in baking, such as commercial emulsifier blends, suitably comprising diacetyl tartaric acid ester of mono- and triglycerides, with calcium carbonate as carrier.

Additionally optional shortening, such as butter, edible oil etc may be added.

Formation of stable solid foam structure (eg bread) and an elastic food matrix (eg. pasta) from the faba bean ingredients may further be improved by the use of texturizing agents such as gums and enzymes in production steps.

As the faba bean ingredients obtained according to the method of the invention have a GABA content typicaliy varying from 1030 to 1230 mg/kg of GABA, a bread made with 100 g of processed faba bean flour (faba bean ingredient flour) and of the final weight of 160g ca. (considering a dough yield of 160, for instance), we have 10 mg of GABA in less than 20g of bread, which is a very high value.

Processing of faba beans with the method of the invention results in high protein gluten- free breads with improved nutritional profile, textural and sensory properties compared to control soy flour based bread. One of the challenges in gluten-free breads is to have high volume, elastic texture with a slow starch retrogradation rate. Processed faba bean flour bread has larger volume, bigger and more uniform air cells and they are softer compared to bread produced with soy flour. Processing of the faba beans further improves the structure (more elastic texture) and slows down starch staling rate. Fermentation has a big impact on the nutritional profile. It increases the amount essential amino acids as well as produces GABA.

Additionally, a significant reduction in the starch hydrolysis rate (HI) may be achieved which is extremely important in providing low glycemic responses. The HI value for processed faba bean bread is lower than that that for unprocessed faba bean bread and soy bread.

The invention will now be illustrated with the following examples, where the present invention has been described herein with reference to specific embodiments.

It is, however clear to those skilled in the art that the methods and products may be varied within the scope of the claims.

Examples Example 1

Manufacture of gluten-free bread

Bread is manufactured from unprocessed faba bean flour containing 30 wt% of protein (control I=maize starch : unprocessed faba bean flour 50: 50), from soy flour (control II=maize starch : soy flour 60 :40) and processed faba bean ingredient (flour) containing 40.3 wt% of protein, with maize starch : processed faba bean ingredient (flour) 50 : 50. Soy flour is used for control purposes. The manufacture is carried out in a conventional manner using baker's yeast as the leavening agent. The emulsifier is a commercial emulsifier blend. In following Table 1 the compositions and amount of ingredients are presented . Table 1. Ingredients used in bread samples

Bread manufactured from processed faba bean flour is obtained having improved hardness, cohesiveness, springiness, gummines and chewiness properties in view of control breads.

Starch hydrolysis index (HI) and calculated glycemic index (GI) of the above breads and white wheat bread and rye bread as further controls are presented in Table 2 below. The expected GI is calculated from in vitro HI values using the following formula : Expected GI = 8.198 + 0.8262x HI

Table 2. In vitro HI and calculated GI

In vitro (HI) Expected GI

White wheat bread 100 90.8

Rye bread 83.6 77.3

Control I 85.3 78.7

Control II 85.9 79.2

Faba bread (proc.) 74.9 70.1 Example 2

Determination of antinutritional factors

Antinutritional factors in faba bean flour, in its fractions and in the respective incubated controls and processed samples were determined and they are presented in following table 3.

Table 3. Anti-nutritional factors in faba bean flour, in its fractions and in the respective incubated controls and fermented samples.

Vicine Reduction Convicine Reduction Trypsin Reduction Condensed Phytic acid

(mg/g dm % of (mg/g dm % of inhibitor % of tannins (eq (mg/g dm

±SD) vicine ±SD) convicine activity (TI trypsin cat/lOOg ±SD)

(n = 3) (n = 3) unit/mg dm inhibitor dm ±SD) (n = 2)

±SD) (n = 2) activity (n = 3)

Faba bean 11.46±0.22 6.24±0.14 2.09±0.09 17.13± 1.30 22.89± 1.30 flour

Incubated 7.76±0.12 3.62±0.10 2.36±0.12 23.08±2.99 23.40± 1.09 faba bean

flour control

Fermented 0.67±0.01 94.2 0.56±0.01 91.0 0.91±0.04 56.5 13.71±0.79 23.88±0.35 faba bean

flour

Protein rich 15.85±0.15 8.54±0.15 4.23±0.69 19.62±0.64 32.49±0.55 fraction

Incubated 12.41±0.13 6.91±0.14 4.09±0.19 31.10±2.34 33.46±0.17 protein rich

fraction

control

Fermented 0.77±0.01 95.2 0.77±0.01 91.0 0.57±0.02 86.6 14.92±0.40 36.23±0.74 protein rich

fractions

Starch rich 5.17±0.07 2.71±0.05 0.47±0.09 13.54±0.34 8.27±0.92 fraction

Incubated 3.31±0.03 1.50±0.02 0.92±0.00 16.80±0.70 8.63±0.68 starch rich

fraction

control

Fermented 0.47±0.01 90.8 1.22±0.02 54.9 ND* 100 12.80±0.07 8.50±0.67 starch rich

fraction

5 *ND = not detected