KATINA, Kati (P.O. Box 1000, Vtt, FI-02044, FI)
LEHTINEN, Pekka (P.O. Box 1000, Vtt, FI-02044, FI)
POUTANEN, Kaisa (P.O. Box 1000, Vtt, FI-02044, FI)
KAUKOVIRTA-NORJA, Anu (P.O. Box 1000, Vtt, FI-02044, FI)
MYLLYMÄKI, Olavi (P.O. Box 1000, Vtt, FI-02044, FI)
KATINA, Kati (P.O. Box 1000, Vtt, FI-02044, FI)
LEHTINEN, Pekka (P.O. Box 1000, Vtt, FI-02044, FI)
POUTANEN, Kaisa (P.O. Box 1000, Vtt, FI-02044, FI)
KAUKOVIRTA-NORJA, Anu (P.O. Box 1000, Vtt, FI-02044, FI)
| CLAIMS: 1. A method of treating rye into a fermented rye fraction, where a desired fraction is separated from wholemeal rye and is fermented, characterized in that - the outer surface of wholemeal rye is polished by 5 - 30 %; — bran, wholemeal flour or other fraction containing nutritional fibre is separated from the polished rye grain; and - the separated fraction is treated by fermenting it into a fermented rye fraction. 2. The method according to Claim 1, characterized in that the fermented fraction is used as such as the raw material of foodstuffs, or it is dried and the dried fraction thus obtained is used as a dry ingredient as the raw material of foodstuffs. 3. A method of treating rye into a rye-based preparation, where a desired fraction is separated from wholemeal rye, is fermented and is further treated, characterized in that - the outer surface of the wholemeal rye is polished by 5 - 30 %; - bran, wholemeal flour or other fraction containing nutritional fibre is separated from the polished rye grain; - the separated fraction is treated by fermenting it into a fermented rye-based fraction; - the fermented fraction is blended into a subcomponent of a dough mixture or with carrier flour; and - a rye-based preparation is extruded or baked from the blended mixture. 4. The method according to Claim 3, characterized in that - an undried fermented fraction is blended into a subcomponent of a dough mixture, where part of the water needed in the baking process is obtained from the undried fermented bran; and - a rye-based preparation is baked from the blended mixture. 5. The method according to Claim 3, characterized in that - the fermented fraction is dried; - the dried fermented fraction is blended with starch-bearing carrier flour, preferably a baking flour mixture; and — a rye-based preparation is extruded from the blended mixture. 6. The method according to any of Claims 1 - 5, characterized in that the outer surface of the wholemeal rye is polished by 5 - 25 %, most suitably 15 - 24 %, before separating the bran, flour or other fraction. 7. The method according to any of Claims 1 - 6, characterized in that rye bran is separated from the polished rye grains. 8. The method according to any of Claims 1 - 7, characterized in that the fermentation is carried out using a lactic acid bacterial strain, yeast strain or a mixture thereof, preferably a bacterial strain of the Lactobacillus genus or the Saccharomyces cerevisiae yeast. 9. The method according to any of Claims 1 - 8, characterized in that the fermented rye fraction is blended with starch-bearing flour, so that the portion of fermented rye fraction from the dry matter of the mixture is 20 - 80 weight-%, preferably 20 - 60 weight-%, most suitably 25 - 40 weight-%. 10. A rye-based product, characterized in being manufactured by the method according to any of Claims 1 - 9, whereby it either consists of a fermented rye fraction or a fermented, blended and extruded or baked rye preparation. 11. A food product, characterized in containing the rye-based product according to Claim 10. 12. The food product according to Claim 11, characterized in containing 1 - 25 weight-% of the rye-based product according to Claim 10, which is manufactured by the method according to any of Claims 1 - 9, whereby it either contains a fermented rye fraction or a fermented, blended and extruded rye preparation. 13. The food product according to Claim 11 or 12, characterized in being a breakfast cereal, bread product, pastry product or beverage product. 14. The food product according to Claim 13, characterized in that the product is a breakfast cereal, the fibre content of which is 6 - 20 weight- % and the main source of fibre being rye. 15. The food product according to Claim 13, characterized in that the product is a bread product, the fibre content of which is between 6 - 20 weight-% and the main source of fibre being rye. 16. The food product according to Claim 13, characterized in that the product is a pastry product, which is a yeast dough-based product, the fibre content of which is 6 - 12 weight- % and the main source of fibre being rye. 17. The food product according to Claim 13, characterized in that the product is a beverage product that contains 1 - 5 weight-% of rye bran and the main source of fibre being rye. |
Field of the invention
The present invention relates to a method of treating wholemeal rye and the fractions obtained therefrom into a form suitable for foodstuffs, and to the rye-based products thus obtained and the food products further prepared therefrom.
Description of prior art
Wholemeal rye, particularly the husk layer of rye, contains a lot of fibre and bioactive compounds. Numerous international studies have proven that the outermost layers of rye grains (the bran) decrease the risk of contracting, for example, cardio-vascular diseases or adult-onset diabetes, and associated health statements are being prepared. Thus, an interest to use rye and its husk layers, in addition to conventional bakery products, also in new types of grain applications, such as extrusion products, has increased to a great extent even in cuisines that conventionally use wheat, such as in the U.S.A. Exploitation of conventional rye (wholemeal flour or bran), for example in extrusion products can be difficult due to the strong (bitter) taste of rye and its poor technological properties: an extrusion product containing conventional wholemeal rye or bran has a strong and often bitter flavour of rye and a hard and chewy texture.
Bran is a good starting point for developing nutritionally valuable and tasty grain-based products with good textures (Katina, K; Laitila, A; Juvonen, R, et al.: FOOD MICROBIOLOGY, Volume 2, No. 2, pp. 175-186, published in 2007).
Thus, one problem of the rye products conventionally used as foodstuff is that they either are soft or hard breads (of the crisp rye-bread type); and in geographical areas, where the inhabitants are accustomed to consuming wheat bread, the taste of the products is sometimes perceived as too strong and bitter. Brief description of the invention
It is an object of the present invention to provide a new rye-based product, which gives the food products containing it a more pleasant taste and texture than previously.
Particularly, it is an object of the present invention to provide a new fermented rye-based product from the parts of rye that are rich in nutritious fibre and bioactive compounds, which product further gives the foodstuff containing it a more pleasant taste and texture than previously.
Thus, the present invention relates to a method of treating rye, wherein the desired fraction is separated from wholemeal rye and is further treated. The invention also relates to food products that contain the preparation thus obtained.
More precisely, the methods according to the present invention are characterized in what is stated in the characterizing parts of Claims 1 and 3.
The rye-based product according to the present invention, in turn, is characterized in what is stated in Claim 10, and the food product according to the invention is characterized in what is stated in Claim 11.
In the invention, components that impair the flavour, taste and technical properties are mechanically removed from the rye grains. By removing the pericarp and testa layers of the surface parts, which are bitter and microbiologically impure, the taste of the rye is improved and the number of microbes inherently found in the grain is decreased. The falling number of the polished grain becomes higher than that of unpolished grain. The microbial load of the rye surface and their toxic metabolites are almost fully removed, when the polishing degree of the grain exceeds 11 % (G. Bennett and J. Richard, Influence of processing on Fusarium mycotoxins in contaminated grains, Food Technol. 50 (1996) (5), pp. 235 - 238). In the invention, the polished rye grain thus obtained is further treated by a mechanical and microbiological treatment. Detailed description of the preferred embodiments of the invention
The present invention relates to a method of treating rye, wherein bran, wholemeal flour or other fraction containing nutritious fibre is separated from wholemeal rye or polished rye grains, after which the separated fraction is treated by fermentation. In this way, a fermented rye-based fraction is obtained.
According to a preferred embodiment of the invention, the outer surface of the wholemeal rye is polished by 5 - 30 %, preferably 5 - 25 %, more preferably 15 - 24 % before separating the desired fraction(s). The polishing is optionally followed by one or more cycles, where the grains are milled and the obtained flour is classified according to which fraction sizes are to be separated from the rye.
The fermentation is preferably carried out using lactic acid bacteria, yeast or a mixture thereof.
The prepared fermented rye-based fraction can be used in foodstuffs either as such, or it can be used as an intermediate product and further treated into a product that has a different texture, whereby the fermented fraction is blended into a partial component of a dough mixture, or it is blended with carrier flour, preferably wheat flour, to an appropriate concentration, such as a concentration of 20 - 80 % by weight, preferably 20 - 60 % by weight, most preferably 25 - 40 % by weight, and a crisp rye-based product is formed from the obtained mixture by extruding or baking, which as a consequence of this treatment has a particularly crisp and satisfying texture compared with conventional rye products.
The crisp rye-based preparation thus obtained is extremely well suited to be used in foodstuffs. The preparation mainly differs from the above-mentioned fermented fraction as to its texture. Both preparations (both the fermented rye-based fraction and the fermented, blended and extruded or baked preparation) have the advantageous taste properties enabled by the present invention.
According to a preferred embodiment, the undried fermented fraction is either blended into a subcomponent of the dough mixture, where part of the water required by the baking process is obtained from undried, fermented bran, and the rye-based preparation is baked from the blended mixture, or the fermented fraction is dried, blended with starch-bearing carrier flour, preferably a baking flour mixture, and the rye-based preparation is extruded from the blended mixture.
Despite its positive health image, the international commercialization of rye definitely requires considerable modification of both the taste and technological properties of rye or its fractions, particularly the fibre-bearing husk fractions, more particularly the bran.
The present invention consists of mechanical, thermo-mechanical and biotechnical operations and processes, where the fractioning and fermenting technology that modifies the taste can, when so desired, be combined with an extrusion process that forms the texture. The fibre content and bioactivity of such a rye extrusion product are also high.
In particular, the bran portion of rye contains a lot of fibre. In Nordic nutrition, rye generally provides a lot of fibre. Rye is rich in vitamins B, magnesium, potassium, iron, zinc, copper and manganese. The bran portion of rye, again, is rich in bioactive compounds, such as lignanes, alkyl resorcinols, phenolic acids, phytosterols, tocopherols, and tocotrienols and folates. However, people in the rest of the world are not accustomed to the taste of rye products in the same way as they are in the Nordic Countries.
Sour dough fermentation is a biotechnical process, which makes possible to influence, for example, the said taste, texture and amount of bioactive components of bread. It can be used to decelerate the absorption of starch and to increase the availability of minerals. In the present invention, fermentation is used for strengthening the aroma typical of rye or the taste profile of products made of rye by changing the fermentation parameters.
The natural lactic acid bacteria and enzymes of rye are concentrated in the outer parts of the grain; the bran, in particular, and they have a high impact on the result of fermentation, which can be modified, among others, by the polishing degree of the grain, by grinding the polished grain, and by the separation process of bran from the milled, polished rye. The manufacture of bran by fine grinding and air classification methods decreases the concentration of bitter phenolic surface layers, which when fine-ground, are mainly discharged to the fine fraction of classification, when the parameters are adjusted correctly. According to a preferred embodiment of the present invention, milling and classification are thus used in the preparation of the rye-based preparation, particularly fine grinding and air classification, for removing the finest fractions from the treated rye fractions. According to this embodiment, particles with a diameter of less than 0.1 mm are separated from the fractions; preferably particles with a diameter of less than 0.2 mm, and most preferably those with a diameter of less than 0.3 mm.
The controlled fermentation of both polished and unpolished rye bran increases the content of folate as well as the content of extractible phenolic compounds and ferulic acid. The alkyl resorcinols increase, when the fermentation is carried out on native rye grain, but decrease when the fermentation is carried out on polished rye grain. In both cases, the amount of soluble pentosans increases in a fermentation of 12 - 14 hours at 25 °C. The relief of microbial load by polishing has an effect on the population of microbes of the yeast fermentation (Katina, K; Laitila, A; Juvonen, R, et al.: FOOD MICROBIOLOGY, Volume 24, No. 2, pp. 175 - 186, published in 2007). According to an embodiment, whole rye is used as the raw material of fermentation and it is preferably further treated after the fermentation according to the invention, particularly by extrusion, whereby a crisp product is obtained, which is suited for a snack product, for example. The crisp extrudate of whole rye thus obtained has a mildly sour, intensive flavour and aftertaste. In the present invention, the fermentation is carried out under typical conditions that correspond to the fermentation of grain, for example at 25 °C, preferably with a lactic acid bacterial strain, yeast strain or a mixture of several strains, such as a mixture of various lactic acid bacterial strains, a mixture of various yeast strains or a mixture containing one or more bacterial strains and one or more yeast strains. The lactic acid bacterial strain more preferably used comprises a strain of the Lactobacillus genus and the yeast strain comprises Saccharomyces cerevisiae yeast. The bacterial strain most suitably used is the bacterial strain of the Lactobacillus genus. The fermentation time is preferably 10 - 24 hours, more preferably 12 - 14 hours, and most preferably about 12 hours. The method according to the invention considerably improves both the taste and the technological properties of rye, which is why the fermented rye-based product provided by the method is suitable for the raw material of new types of rye-based foodstuffs. These foodstuffs include breakfast cereal, bread products, pastry products, other rye snacks and beverage products, preferably breakfast cereal and rye snacks.
Thus, the food product according to the invention contains the rye-based product prepared by the method according to the invention, i.e., the fermented rye-based fraction, which is manufactured by separating, from wholemeal rye, the bran, wholemeal flour or another fraction of the husk layers of the grain, and by fermenting the separated fraction and by optionally drying the fermented fraction, blending it with starch-bearing carrier flour and extruding the mixture thus obtained. The separation stage of the desired fractions can optionally also be preceded by the polishing stage of the outer surface of wholemeal rye. The food product preferably contains 1 - 25 weight- % of the rye-based product thus obtained, more preferably 5 - 25 weight- %, and most suitably 10 - 20 weight- %. According to a preferred embodiment of the invention, the main fibre source of these food products is rye. In addition:
- the fibre content of the breakfast cereal is 6 - 20 weight-%, preferably 10 - 18 weight- %;
- the fibre content of the bread product is between 6 - 20 weight-%, preferably 10 - 18 weight-%, and it has properties corresponding to wheat/mixed wheat bread as to its colour, taste and texture;
- the pastry product (of a brioche type) is a confectionery product with a yeast dough base and a fibre content of 6 - 12 weight-%, preferably 8 - 10 weight-%, its taste and texture not considerably deviating from corresponding conventional confectionery products; and
- the beverage product contains 1 - 5 weight-% of rye bran.
In addition to the rye-based product according to the invention, these food products may contain other ingredients that are conventionally used in the manufacture of foodstuffs, particularly nutritional ingredients, such as those containing fibre, protein, vitamins and trace elements. The following, non-limiting examples describe the invention and its advantages. Examples
Example 1 - fermentation and extrusion of wholemeal rye: the effect of fermentation on the taste components Commercial wholemeal rye flour was used as the raw material. The flour was fermented and the fermented flour was extruded using an APV MPF 19/2 twin-screw extruder, which in addition to the forward screw elements had 9 blocking screw elements and 10 stirring disc elements. The temperature of the zones in the extrusion was 140 °C, the material feed was 50 g/min and the nozzle was a 3 mm nozzle. The moisture content of the extrudate was 19 %.
The extruded product was dried by a blast drier and the volatile compounds, which described the quality that could be sensed, were determined. A reference comprised an extrudate that was made of untreated rye, which was harder.
Example 2 - polishing of rye, separation and treatment of fractions Whole rye grains were polished by a grinding machine of the Rattinger Machinery, which functions on a vertical axis. The device comprises seven grinding stones, which are surrounded by a screen plate at a distance of 12 mm from the grinding stones. Air is blown through the screen mesh, keeping the screen mesh open. The degree of polishing is adjusted by adjusting the dwell time of the grains in the device, i.e., the flow velocity of the grains from the inlet of the device to its outlet. The capacity of the device is about 1000 kg/h. Before polishing, the moisture content of rye was increased by about 2-3 %.
The rye grains were polished 24 % using this equipment. The polished rye grains were milled by the UPZ 100 mill of Hosokawa- Alpine and a 0.3 mm screen at 18000 rpm. The flour was classified by British Rema at 3500 rpm and 220 m 3 /h. The first classification yielded 32 % of bran fraction, calculated from unpolished rye grain. This bran was milled again by the UPZ 100 mill of Hosokawa- Alpine and a 0.3 mm screen at L8000 rpm. The Hour was classified by British Rema at 3500 rpm and 220 m 3 /h. A bran fraction was thus obtained, the yield of which was 17.2 % of polished rye grain, i.e. 13 % of unpolished rye grain.
The rye bran was fermented with yeast or a mixture of yeast and Lb. brevis at a temperature of +20 °C for 16 h. The fermented rye bran was dried in a freeze-drier. 30 % of bran fermented in the extrusion process, where the amount of bioactive compounds was increased, was blended with wheat flour that modifies the texture, and 0.9 % of salt was added to the mixture. The mixture was extruded using APV MPF 19/25 twin-screw extrusion at a moisture of 19-23 % at a temperature of 130 °C, by a 3 mm nozzle, the rotational speed of the screws being 350 rpm. A crisp and light extrudate with advantageous properties was provided when the extruder load was over 70 %. No bitterness characterized of rye was noticed in the taste.
Simultaneously, a reference test was carried out on unfermented rye bran. Under the same conditions, the reference bran was more bitter than the fermented extrudate made of polished rye. The product of the invention had a higher folate content (55 g/100 g), while the folate content of the unfermented reference product was clearly lower (30 g/100 g). A snack product was made of the product, which provided a product with a crisp texture, which was easy to eat. It is easy to change its shape and texture.
Example 3 - polishing and fermenting of rye and its use in baking Whole rye grains were polished by a grinding machine of the Rattinger Machinery, which functions on a vertical axis. The device comprises seven grinding stones, which are surrounded by a screen plate at a distance of 12 mm from the grinding stones. Air is blown through the screen mesh, keeping the screen mesh open. The degree of polishing is adjusted by adjusting the dwell time of the grains in the device, i.e., the flow velocity of the grains from the inlet of the device to its outlet. The capacity of the device is about 1000 kg/h. Before polishing, the moisture content of rye was increased by about 2-3 %. The rye grains were polished by this equipment so that 24 % of the mass of the grains was removed. The polished rye grains were milled using the UPZ 100 mill of Hosokawa- Alpine and a 0.3 mm screen at 18000 rpm. The flour was classified by British Rema at 3500 rpm and 220 m 3 /h. The first classification yielded 32 % of bran fraction, calculated from unpolished rye grain. This bran was milled again by the UPZ 100 mill of Hosokawa- Alpine and the 0.3 mm screen at 18000 rpm. The flour was classified by British Rema at 3500 rpm and 220 m 3 /h. A bran fraction was thus obtained, the yield of which was 17.2 % of polished rye grain, i.e. 13 % of unpolished rye grain.
Water was added to the rye bran and it was fermented with S. cerevisiae yeast at a temperature of +20 °C for 23 h. In reference fermentation, unpolished bran was fermented under the same conditions. After the fermentation, the pH of the polished, fermented bran was 4.7 and its acid value 6.3. The corresponding values in reference fermentation were 5.3 and 11.5.
The extruded, fermented bran was added to the baking process of conventional wheat bread on a level of increase of 20 % (20 % of flour was replaced with bran). The reference that was used comprised unfermented polished bran and unpolished bran as such and when fermented. The specific volume and hardness were determined for finished loaves of bread on the day of baking and after 3 days of storage. A sensory assessment was also conducted on the bread. The volume of the reference bread (polished or unpolished rye bran) was 3.8 - 3.9 ml/g. When using unpolished, fermented bran, the volume was 4.0 ml/g. The volume of bread containing polished, fermented rye bran was 4.5 ml/g; therefore, an improvement of 12 % in the specific volume of the bread was obtained by the combination process. The softness of fresh bread also improved by 25 , when using the fermented, polished bran in the baking, compared with the reference bread. The fermented bread had a colour similar to wheat bread and its taste was assessed as being mild and not tangy.