GLUTEN-FREE BREAD

Abstract

The present invention generally relates to gluten-free food products. In particular, the present invention concerns gluten-free bread comprising starch-containing material and Brassicaceae seed protein. Further aspects of the invention are a process for manufacturing gluten-free bread, a gluten-free food product and a gluten-free dough.

Claims

1. Gluten-free bread comprising a gluten-free starch-containing material and between 0.5 and 15 wt. % Brassicaceae seed protein on a dry basis.

2. Gluten-free bread according to claim 1 comprising on a dry basis 0.5 to 15 wt. % Brassicaceae seed protein, 50 to 90 wt. % starch, 0 to 8 wt. % yeast, 0 to 10 wt. % sugar, 0 to 10 wt. % oil, 0 to 10 wt. % fat and 0 to 3 wt. % salt.

3. Gluten-free bread according to claim 1 wherein the starch-containing material is selected from the group consisting of maize starch, corn meal, buckwheat flour, millet flour, amaranth flour, quinoa flour, potato starch, sweet potato flour, tapioca starch, rice starch, rice flour, sorghum flour, bean flour, pea flour, pea starch, soy flour, chickpea flour, cowpea flour, lentil flour, bambara bean flour, lupin flour, chestnut flour and combinations thereof.

4. Gluten-free bread according to claim 1 wherein the Brassicaceae seed protein is obtained from seeds selected from the group consisting of Brassica napus, Brassica rapa, Brassica juncea, Brassica nigra, Brassica hirta and combinations thereof.

5. Gluten-free bread according to claim 1 wherein the Brassicaceae seed protein is selected from the group consisting of rapeseed and canola protein.

6. Gluten-free bread according to claim 1 wherein the Brassicaceae seed protein is selected from the group consisting of a protein isolate and a protein concentrate.

7. Gluten-free bread according to claim 1 which is free of agar-agar, carrageenan, gum Arabic, tragacanth, locust bean gum, guar gum, cellulose derivatives and xanthan gum.

8. Gluten-free bread according to claim 1 which is free from milk protein and egg protein.

9. Gluten-free bread according to claim 1 which is selected from the group consisting of pizza bases, focaccia and bread buns.

10. Gluten-free food product comprising a gluten-free bread comprising a gluten-free starch-containing material and between 0.5 and 15 wt. % Brassicaceae seed protein on a dry basis.

11. Gluten-free food product according to claim 10 which is a pizza.

12. Process for manufacturing gluten-free bread, the process comprising preparing a gluten-free dough comprising between 30 to 50 wt. % water and, on a dry basis, 0.5 to 15 wt. % Brassicaceae seed protein, 50 to 90 wt. % starch, 0 to 8 wt. % yeast, 0 to 10 wt. % sugar, 0 to 10 wt. % oil, 0 to 10 wt. % fat, and 0 to 3 wt. % salt; and cooking the dough.

13. Process for manufacturing gluten-free bread according to claim 12, the process comprising: preparing a gluten-free dough comprising between 30 to 50 wt. % water and, on a dry basis, 0.5 to 15 wt. % Brassicaceae seed protein, 50 to 90 wt. % starch, 0.5 to 8 wt. % yeast, 0 to 10 wt. % sugar, 0 to 10 wt. % oil, 0 to 10 wt. % fat, and 0 to 3 wt. % salt; proofing the dough at a temperature of between 25 C. and 40 C. for at least 30 minutes; and cooking the dough to form a bread.

14. Gluten-free dough for making gluten-free bread, the dough comprising between 30 and 50 wt. % water and, on a dry basis, 0.5 to 15 wt. % Brassicaceae seed protein, 50 to 90 wt. % starch, 0 to 8 wt. % yeast, 0 to 10 wt. % sugar, 0 to 10 wt. % oil, 0 to 10 wt. % fat and 0 to 3 wt. % salt.

15. Gluten-free dough according to claim 14 wherein the dough is a chilled or frozen ready-to bake dough.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0017] FIG. 1 is a photograph of different breads from the examples formed as pizza bases.

[0018] FIG. 2 is a photograph of bread made with egg white (left-hand-side) and bread with a mixture of Canola and potato protein isolates (right-hand-side). Both breads have been lightly pressed, the depression remains on the bread made with egg white.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Consequently the present invention relates in part to a gluten-free bread comprising a gluten-free starch-containing material and between 0.5 and 15 wt. % Brassicaceae seed protein on a dry basis. The term gluten-free in the current specification refers to products with less than 20 ppm gluten, which is the definition from Codex Alimentarius Standard 118-1979. The starch-containing material may be starch itself, or it may for example be a non-gluten flour such as rice flour.

[0020] Removal of gluten from bread formulations in turn reduces the protein content and therefore the nutritional value of the bread. Using Brassicaceae seed protein as a gluten replacement, rather than for example gums and emulsifiers, provides a more nutritious gluten-free bread. As Brassicaceae seeds are generally grown for their oil, Brassicaceae seeds may provide an inexpensive source of protein as a by-product of oil production. It is therefore advantageous to be able to use Brassicaceae seed protein to manufacture gluten-free bread. In addition, acceptable breads can be obtained using low levels of Brassicaceae seed protein which may reduce the cost still further compared to other gluten substitute proteins. The gluten-free bread may comprise between 0.5 and 10 wt. % Brassicaceae seed protein on a dry basis, for example between 1 and 5 wt. % Brassicaceae seed protein on a dry basis.

[0021] The main component of traditional breads is starch. In a traditional wheat-based bread the starch is contained in wheat flour and it is the formation of a gluten-starch matrix which provides the desirable texture of bread. Other typical bread ingredients are oils and fats, salt and, for yeast-fermented breads, yeast. The gluten-free bread of the invention may comprise on a dry basis 0.5 to 15 wt. % Brassicaceae seed protein, 50 to 90 wt. % starch, 0 to 8 wt. % yeast, 0 to 10 wt. % sugar, 0 to 10 wt. % oil and/or fat and 0 to 3 wt. % salt. The sugar may be in many forms, for example crystalline sucrose, molasses or honey. The oil may be, for example, a vegetable oil such as sunflower oil or olive oil. The fat may be for example butter or margarine. The gluten-free bread of the current invention may also contain other ingredients such as such as spices, fruit (such as raisins), vegetables (such as onion), nuts (such as walnuts) or seeds (such as poppy). The term starch is used in the conventional manner to refer to a carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. Starch does not contain gluten.

[0022] The starch-containing material comprised within the gluten-free bread of the invention may be gluten-free ground cereals, pulses, roots or mixtures of these. The gluten-free starch-containing material comprised within the gluten-free bread of the invention may be selected from the group consisting of maize starch, corn meal, buckwheat flour, millet flour, amaranth flour, quinoa flour, potato starch, sweet potato flour, tapioca starch, rice starch, rice flour, sorghum flour, bean flour, pea flour, pea starch, soy flour, chickpea flour, cowpea flour, lentil flour, bambara bean flour, lupin flour, chestnut flour and combinations of these. For example the starch-containing material may be a mixture of corn starch, potato starch and white rice flour, which mixture provides particularly good texture, moisture retention and final bread quality. For a darker colour, the gluten-free starch-containing material may be a mixture of corn starch, potato starch and brown rice flour. The gluten-free starch-containing material may be a mixture of tapioca starch, potato starch and rice flour. The gluten-free starch-containing material of the gluten-free bread of the invention may comprise between 30 and 50 wt. % flour. For example the gluten-free starch-containing material may contain between 10 and 30 wt. % corn starch, between 30 and 50 wt. % potato starch and between 30 and 50 wt. % rice flour. The gluten-free bread of the invention may comprise a natural source of non-starch polysaccharides such as from fruit, vegetable, cereal, pseudocereal or legume source. Adding non-starch polysaccharides fibre ingredients improves the bread texture by providing the textural attributes that would be provided by wheat fibre in conventional wheat-based bread. For example the non-starch polysaccharides may be gluten-free cereal bran, beet fibre, fruit pectin or pea fibre. To further enhance the nutritional value of the bread, the gluten-free bread of the invention may also comprise iron, folic acid, and other B vitamins.

[0023] Pentosans (polysaccharides composed of pentoses) have the undesirable effect in bread of binding water and preventing the dough from expanding fully, this leads to low bread volumes. Preferably the gluten-free bread of the invention is low in pentosans, for example the ratio of starch to pentosans may be greater than 30:1.

[0024] The Brassicaceae seed protein comprised within the gluten-free bread of the invention may be obtained from seeds selected from the group consisting of Brassica napus, Brassica rapa, Brassica juncea, Brassica nigra, Brassica hirta and combinations of these. The Brassicaceae seed protein may for example be rapeseed or canola protein. Canola is the Canadian oilseed crop developed primarily for the purpose of edible oil. It was naturally bred to reduce erucic acid in the oil and glucosinolates in the meal. The plants are cultivars of either rapeseed (Brassica napus) or field mustard/turnip rape (Brassica rapa). Recent cross-breeding of multiples lines of Brassica juncea have enabled this mustard variety to also be classified as a Canola variety. Canola is defined as seeds of the genus Brassica (Brassica napus, Brassica rapa or Brassica juncea) from which the oil shall contain less than 2% erucic acid in its fatty acid profile and the solid component shall contain less than 30 micromoles of any one or any mixture of 3-butenyl glucosinolate, 4-pentenyl glucosinolate, 2-hydroxy-3 butenyl glucosinolate, and 2-hydroxy-4-pentenyl glucosinolate per gram of air-dry, oil-free solid. Canola protein forms aggregates which mimic the rheological characteristics of hydrated gluten proteins making Canola protein particularly suitable as a gluten replacer in bread.

[0025] The Brassicaceae seed protein comprised within the gluten-free bread of the invention may be in the form of a protein isolate or a protein concentrate. Concentrates are typically considered to be between 40-89 wt. % protein on a dry basis, while 90 wt. % protein and above is considered as protein isolate. Protein isolates may be obtained from defatted Brassicaceae seeds by a number of extraction and purification processes, such as extraction with alkaline solution, enzymatic extraction, methods involving the formation of a protein micellar mass, salting out the protein with NaCl or combinations of these processes. Methods for obtaining Canola protein isolates are summarized by Tan [S. H. Tan et al., J Food Sci., 76, R16-R28 (2011)]. At least part of the Brassicaceae seed protein comprised within the gluten-free bread of the invention may be in its native form, for example at least 20 wt. % of the Brassicaceae seed protein comprised within the gluten-free bread of the invention may be in its native form.

[0026] Non-starch hydrocolloids are often used in gluten-free breads, acting to stabilize the bread. However, use of these materials may lead to a brittle, crumbly final texture. In addition, consumers are accustomed to the bread they eat being made from only a small number of preferably familiar ingredients and so it is beneficial that by using Brassicaceae seed protein as a gluten replacer the addition of non-starch hydrocolloids may be avoided. The gluten-free bread of the invention may be free from agar-agar, carrageenan, gum Arabic, tragacanth, locust bean gum, guar gum, cellulose derivatives and xanthan gum. The gluten-free bread of the invention may be free from modified starch; that is starch prepared by enzymatically, or chemically treating native starch, thereby altering its properties.

[0027] The gluten-free bread of the invention may comprise potato protein in addition to the Brassicaceae seed protein, for example the gluten-free bread of the invention may comprise potato protein isolate. The inventors have found that the addition of potato protein improves resistance to hardening on storage.

[0028] Milk proteins and egg proteins are used in a number of gluten-free bread recipes. Milk proteins in particular are able to build up a network structure similar to gluten. Unfortunately, some consumers are allergic to milk or egg proteins, or chose not to eat them due to their animal origin, e.g. vegans. It is therefore beneficial that, by using Brassicaceae seed protein as a gluten replacer, an acceptable bread may be obtained without the use of milk or egg proteins. The gluten-free bread of the invention may be free from milk protein and egg protein.

[0029] The gluten-free bread of the invention may be in various forms. The gluten-free bread may be leavened (aerated) or unleavened. It may be leavened by a number of different processes including the use of naturally occurring microbes, the addition of yeast, the addition of chemical leavening agents such as baking powder and baking soda, or high-pressure artificial aeration during preparation and/or baking. Western-style yeast-leavened bread with a very aerated structure is particularly difficult to make without the functionality of gluten, so it is beneficial that, by using Brassicaceae seed protein as a gluten replacer, an acceptable bread of this type may be obtained.

[0030] The gluten-free bread of the invention may have a high volume for its weight. For example the gluten-free bread of the invention may have a volume greater than 2.0 cm.sup.3/g, for example greater than 2.5 cm.sup.3/g, for example greater than 2.8 cm.sup.3/g, for further example greater than 3.0 cm.sup.3/g.

[0031] The gluten-free bread of the invention may be selected from the group consisting of pita bread, white bread, brown bread (e.g. made with endosperm and 10% bran), whole-grain bread (with non-gluten containing grains), roti, chapatti, naan, matzo, sourdough bread, flatbread and crisp bread. The gluten-free bread of the invention may be selected from the group consisting of pizza bases, focaccia and bread buns.

[0032] The gluten-free bread of the invention may be comprised within a gluten-free food product. For example the gluten-free bread may be sliced and placed around a filling as a sandwich, it may be in the form of croutons in soup, it may be as breadcrumbs coating a piece of meat or it may be the bread component of a bread and butter pudding. The gluten-free food product comprising the gluten-free bread of the invention may be a pizza.

[0033] In another aspect, the invention provides a process for manufacturing gluten-free bread, the process comprising preparing a gluten-free dough comprising between 30 to 50 wt. % water and, on a dry basis, 0.5 to 15 wt. % Brassicaceae seed protein, 50 to 90 wt. % starch, 0 to 8 wt. % yeast, 0 to 10 wt. % sugar, 0 to 10 wt. % oil and/or fat, and 0 to 3 wt. % salt and cooking the dough. The dough may be cooked by baking or any other of the methods known for cooking bread such as steaming, frying or microwaving. The term gluten-free dough means that the dough contains less than 20 ppm gluten. For example, none of the components of the dough may comprise gluten.

[0034] For breads leavened with yeast, a proofing step may be introduced. Proofing (also called proving) is the final dough-rise step in a yeast-fermented dough before baking, and refers to a period when the bread is left to rise. The process for manufacturing gluten-free bread may comprise preparing a gluten-free dough comprising between 30 to 50 wt. % water and, on a dry basis, 0.5 to 15 wt. % Brassicaceae seed protein, 50 to 90 wt. % starch, 0.5 to 8 wt. % yeast, 0 to 10 wt. % sugar, 0 to 10 wt. % oil and/or fat, and 0 to 3 wt. % salt, proofing the dough at a temperature of between 25 C. and 40 C. for at least 30 minutes and cooking the dough to form a bread.

[0035] In a further aspect, the invention provides a gluten-free dough for making gluten-free bread, the dough comprising between 30 and 50 wt. % water and, on a dry basis, 0.5 to 15 wt. % Brassicaceae seed protein, 50 to 90 wt. % starch, 0 to 8 wt. % yeast, 0 to 10 wt. % sugar, 0 to 10 wt. % oil and/or fat and 0 to 3 wt. % salt. Recent years have shown a growth in supermarkets and roadside service stations having small in-store bakeries which bake bread on the premises. Many of these in-store bakeries use ready-to-bake doughs, so the employees of the bakery do not need to prepare the bread dough themselves. Pre-made bread dough is also available for consumers to purchase and bake bread conveniently at home. Such ready-to-bake dough may be chilled or frozen to both prevent the growth of spoilage organisms and to prevent any bread yeast present from fermenting in storage. Chilled food is typically maintained at temperatures between 2 and 8 C. in storage and transit, while frozen food is typically maintained below 18 C. The gluten-free dough of the invention may be a chilled or frozen ready-to bake dough. For example the chilled or frozen ready-to bake dough may form the base of a chilled or frozen un-baked pizza.

[0036] Those skilled in the art will understand that they can freely combine all features of the present invention disclosed herein. In particular, features described for the products of the present invention may be combined with the process of the present invention and vice versa. Further, features described for different embodiments of the present invention may be combined. Where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred to in this specification. Further advantages and features of the present invention are apparent from the figure and non-limiting examples.

EXAMPLES

[0037] For examples 1 to 6, gluten-free bread comprising Brassicaceae seed protein was compared to a standard wheat flour bread recipe, two commercial gluten-free bread mixes and a negative control. For each recipe, two 250 g loaves were baked in loaf tins and 200 g was formed into a pizza base.

Example 1

Standard Bread with Wheat Flour

[0038] The following ingredients were mixed in a Hobart mixer with a hook element until complete development (dough forms thin film when stretched).

TABLE-US-00001 Ingredient g wheat flour 600 Water 400 Yeast 15 Sugar 10 Salt 10 sunflower oil 30 Total 1065

[0039] The dough was proofed for 30 minutes in a temperature controlled cabinet set at 37 C. and 85% relative humidity, then baked in an oven for 30 minutes at 180 C. The finished bread had a moisture content of 43%.

Example 2

Commercial Gluten-Free Bread Dr Schr

[0040] A gluten-free bread mix was purchased from a supermarket Dr Schr bread mix. The mix contains rice flour, potato starch, sugar, thickeners (hydroxypropyl methyl cellulose, locust bean gum), salt, mono- and diglycerides of fatty acids. The bread-making procedure indicated on the pack was followed. Water was added to the dry ingredients and mixed in a Hobart mixer with a hook element for 5 minutes.

TABLE-US-00002 Ingredients g Dr Schr bread mix 500 Water 500 Yeast 10 Salt 5 sunflower oil 6 Total 1021

[0041] The dough was proofed for 30 minutes in a temperature controlled cabinet set at 37 C. and 85% relative humidity, then baked in an oven for 50 minutes at 200 C. (to be consistent with the on-pack instructions). The finished bread had a moisture content of 53%.

Example 3

Commercial Gluten-Free Bread aha

[0042] A gluten-free bread mix was purchased from a Migros supermarket aha Gluten-free flour mix. The mix contains rice flour, potato starch, buckwheat flour, corn flour, corn starch, fructose and guar gum. The bread-making procedure indicated on the pack was followed. The following ingredients were mixed in a Hobart mixer with a hook element for 8 minutes.

TABLE-US-00003 Ingredients g aha flour mix 500 Water 350 Yeast 7 Sugar 5 Salt 7.5 sunflower oil 26 Total 895.5

[0043] The dough was proofed for 25 minutes in a temperature controlled cabinet set at 37 C. and 85% relative humidity, then baked in an oven for 35 minutes at 200 C. (to be consistent with the on-pack instructions). The finished bread had a moisture content of 43%.

Example 4

Gluten-Free Bread with Brassicaceae Seed Protein

[0044] Canola protein isolate (Isolexx91.4% protein) was purchased from BioExx Specialty Proteins Ltd. The following ingredients were used to form a bread.

TABLE-US-00004 Ingredients g Canola protein isolate (Isolexx) 15 Water 421 corn starch 117 potato starch 234 white rice flour 234 Yeast 15 Sugar 10 Salt 10 sunflower oil 30 Total 1086

[0045] The canola protein isolate was dispersed in 200 g of the water and the sunflower oil was added. The other dry ingredients were then mixed in a Hobart mixer and the canola dispersion was gradually added, followed by the remaining water (to allow adjustment of the mix consistency if required). The dough was proofed for 40 minutes in a temperature controlled cabinet set at 37 C. and 85% relative humidity, then baked in an oven for 30 minutes at 190 C. The finished bread had a moisture content of 44%, a canola protein isolate content of 2.5 wt. % on dry basis and a starch content of about 80 wt. % on a dry basis.

[0046] The recipe was repeated, but with tapioca starch replacing corn starch. This also gave good results, and provided improved resistance to staling.

Example 5

Negative Control

[0047] Example 4 was repeated but with no canola protein isolate present. The finished bread had a moisture content of 44%.

Example 6

[0048] The specific volume after baking and cooling to room temperature was measured by a laser scanner (BVM, Perten Instruments) as the average of two measurements. The texture of the different breads was assessed using a TA-HD texture analyser, using a Texture Profile Analysis macro (compression with a cylindrical probe, the pre-test and post-test speed was 2.0 mm/s, test speed was 1.0 mm/s, distance 8 mm and the load cell was 5 kg). The hardness after baking and cooling to room temperature of bread slices of 2 cm thickness was assessed as the force in Newtons needed to produce a deformation of 40% of the initial height. The measurement was repeated 6 times and the average of the 5 closest was taken. Results are shown in the table below.

TABLE-US-00005 Specific volume Hardness Example cm.sup.3/g Force[N] std dev 1 Wheat flour 4.13 1.9 0.1 2 Dr Schr 2.98 1.9 0.3 3 Aha 1.53 29.8 4.9 4 Canola protein 3.03 1.4 0.3 5 Negative Control 2.72 2.7 0.1

[0049] The specific volume is linked to the capacity of the dough to retain gas cells created during mixing and expanded during fermentation (proofing). This is an important function of gluten proteins in a gluten-containing bread. The bread made with wheat flour had the highest specific volume. Of the gluten-free breads, the highest specific volume was the gluten-free bread made with canola protein (a Brassicaceae seed protein) which was comparable to the gluten-free bread made with commercial Dr Schr bread mix (containing locust bean gum, cellulose derivatives and emulsifiers).

[0050] The hardness of the bread is linked to the porosity of the structure and the thickness of cell walls. Gluten-based breads usually have a higher porosity and thinner cell walls, leading to a softer texture. Of the breads tested, the gluten-free bread made with canola protein was the softest.

[0051] As can be seen in FIG. 1, the gluten-free bread made with canola protein has a macroscopic structure similar to that of the wheat bread.

Example 7

Gluten-Free Bread with Brassicaceae Seed Protein and Potato Protein

[0052] The following ingredients were used to form a bread.

TABLE-US-00006 Ingredients g Canola protein isolate (Isolexx) 10 Potato protein isolate 5 Water 421 corn starch 117 potato starch 234 white rice flour 234 Yeast 15 Sugar 10 Salt 10 sunflower oil 30 Total 1086

[0053] Potato protein was obtained from Solanic (Potato Protein Isolate 306). The canola protein isolate and potato protein isolate were dispersed in 200 g of the water and the sunflower oil was added. The other dry ingredients were then mixed in a Hobart mixer and the protein dispersion was gradually added, followed by the remaining water (to allow adjustment of the mix consistency if required). The dough was proofed for 40 minutes in a temperature controlled cabinet set at 37 C. and 85% relative humidity, then baked in an oven for 30 minutes at 190 C.

[0054] For comparison, the same recipe was made up but with egg white powder as the protein.

TABLE-US-00007 Ingredients g Egg white powder 15 Water 421 corn starch 117 potato starch 234 white rice flour 234 Yeast 15 Sugar 10 Salt 10 sunflower oil 30 Total 1086

[0055] The egg white powder was made up in 200 g of the water and the sunflower oil was added. The other dry ingredients were then mixed in a Hobart mixer and the protein dispersion was gradually added, followed by the remaining water (to allow adjustment of the mix consistency if required). The dough was proofed for 48 minutes in a temperature controlled cabinet set at 37 C. and 85% relative humidity, then baked in an oven for 30 minutes at 190 C.

[0056] The gluten-free bread made with canola and potato protein had a good bread texture, similar to that obtained with wheat flour and a specific volume of 2.95 cm.sup.3/g. The bread made with egg white had a strong taste, rather like an egg-white omelet, and a sticky texture, not desirable in bread. It had a specific volume of 2.49 cm.sup.3/g. After pressing the bread gently with fingers, the canola and potato protein bread sprang straight back, whereas the depression in the surface of the bread made with egg remained (FIG. 2). This confirmed that egg white proteins do not have the required functionality to produce a gluten-free bread with a texture similar to that of a gluten containing bread.