AU2008249175A1

AU2008249175A1 - Dietary Fibre from Plant Material

Info

Publication number: AU2008249175A1
Application number: AU2008249175A
Authority: AU
Inventors: Keith Moulds
Original assignee: BESTLAN BANANAS Pty Ltd
Current assignee: BESTLAN BANANAS Pty Ltd
Priority date: 2006-10-25
Filing date: 2008-11-24
Publication date: 2008-12-11
Also published as: AU2006233185A1

Description

00 DIETARY FIBRE FROM PLANT MATERIAL FIELD OF THE INVENTION The present invention is directed generally to the isolation of dietary fibre from plant material and particularly from plant material of the banana plant. The tn 5 invention includes a method of processing the plant material to give the dietary fibre, as well as the fibre produced by the method of processing.

C, BACKGROUND ART 00 O It has been known for quite some time that people having a diet high in i dietary fibre have lower risk of several diseases. Scientific studies continue to produce new evidence to support the need to increase dietary fibre in the diet.

Dietary fibre is the undigested remains of plant materials, particularly indigestible plant carbohydrates the non-starch polysaccharides). Fibre is found only in foods derived from plants, and all plant food provides some fibre, but the amount of fibre depends on the processing conditions. For instance, unpeeled fruit and vegetables and wholemeal or whole-grain cereal foods (which still contain the outer layers of the grain) will provide the most fibre. Brown rice can contain seven times more fibre than white rice. The exact balance of the various components of dietary fibre (cellulose, hem icelluloses, pectin and lignin) varies between foods.

Dietary fibre can be soluble or insoluble. Soluble fibre includes -glucans, pectins, gums, mucilages and some hemicelluloses. It dissolves in thile gut, to form a viscous gel that slows down the release of some nutrients, particularly thile sugar glucose, into the bloodstream; it is therefore good for diabetics. It can also reduce the risk of heart disease, by reducing blood cholesterol levels. Soluble fibre is present inll fruit, vegetables, pulses kidney beans, baked beans, lentils) and foods containing oats, barley or rye.

Insoluble fibre includes celluloses, some hemicelluloses and lignin. It has a sponge-like effect in the gut, soaking up water and swelling inll size. This effect produces a feeling of fullness and adds bulk to the gut contents, making waste matter heavier and speeding it through the large intestine, thereby reducing the risk of constipation, and possibly even cancers of the digestive system. In the colon, dietary fibre tends to increase faecal bulking due to increased water retention and the insoluble dietary 002 fibre reduces transit time. This is particularly important since the conversion of sterols to O carcinogenic polycyclic aromatic hydrocarbons is known to occur with time.

Epidemiological evidence suggests that low faecal weights are associated with an increased risk of cancer of the colon, dietary fibre may also bind toxins, bile acids and carcinogens. Cereal and grain products bread, flour, breakfast cereals, rice, pasta), especially wholemeal varieties, and fibrous vegetables carrots and celery) are primary sources of insoluble fibre.

0 0The overall nutritional balance of diets could be improved by consuming a O greater amount of high-fibre foods. However, fibre in an isolated form such as bran (the outer layers of cereal grain, which are removed when grain is milled such as in the preparation of white rice or white flour) is not the answer because bran can actually reduce the absorption of minerals. Fibre is thought to be far more beneficial if it is consumed as an integral part of food, rather than as bran supplements or fibre-containing drinks.

The Food and Drug Administration (FDA) of the United States of America, allows health claims relating to dietary fibre on food labels. Several health claims have been authorised referring to the effects of a high fibre, low fat diet in helping to lower the risk of coronary heart disease and cancer. The FDA has recently approved health claims relating to wholegrain foods and prevention of heart disease and cancers.

The prior art describes processing of plant material to a dietary fibre product in various forms. WO 2004/069143 describes the processing of plantains or bananas to give a fibre product for use in the treatment of inflammatory bowel disease.

The bananas are mashed and boiled in water, and to this mixture is added amylase to hydrolyse starch in the raw material. The libre product is optionally precipitated with ethanol.

US 6,838,099 describes the processing of corn hull to give a fibre product.

The starch and protein in the raw material are removed with an alkali treatment; enzymes are added to the material, and the fibre product is filtered.

00 3 US 6,753,019 describes the processing of two or more fruit and/or 0 vegetable extracts to give a fibre product. The juice of the raw material is extracted, and the resulting solid material, when milled and dried, comprises the fibre product.

q ~US 5,622,738 describes a soluble dietary fibre comprising mainly partially hydrolysed hemicellulose, as extracted from vegetable material with alkali, and subsequent enzymolysis.

US 5,112,964 describes processing of rice bran, wheat and grain to give a 00 fibre product. The raw material is treated with amylase to hydrolyse the starch therein.

SThe hydrolysed starch forms a gel, which is removed. Further processing give the fibre product.

It should be appreciated that the mere reference of a publication is not to be seen as an acknowledgement that the publication forms part of the common general knowledge in Australia and overseas.

There would be an advantage in having a simple method of processing fruit and vegetables, the method optionally excluding chemical reaction of starch, which would give a high yield of good quality dietary fibre for human or animal consumption.

SUMMARY OF THE INVENTION It is an object of the invention to provide a dietary fibre from fruit and/or vegetable material, and a method of processing fruit and/or vegetable material to give the dietary fibre, which may overcome at least some of the disadvantages of existing technology or provide a useful or commercial choice.

In one form, the invention resides in a method of preparing a dietary fibre composition from plant material, the method comprising: a.dicing the plant material; b.subjecting the diced material to acid or alkali treatment at room temperature or elevated temperature; c.adding xylanase and/or at least one other enzyme to the treated material to give a crude composition; drying and milling the crude composition to give the dietary fibre composition.

00 4 In a second form, the invention resides in a dietary fibre composition when 0 0 prepared by the method of the first form of the invention.

In another form, the invention resides in a method of preparing a dietary fibre composition from plant material, the method comprising: a. dicing the plant material; b. subjecting the diced material to acid or alkali treatment at room temperature or elevated temperature; and 0 c. drying and milling the crude composition to give the dietary 0 fibre composition.

The plant material will typically be fruit and vegetable plant material. The fruit or vegetable plant material may comprise the fruit, stalks, stemns and roots of the plant. A suitable plant is a banana plant. In particular, green (unripe) banana fruit provide a preferred material. Also preferred are the stalks of the banana plant. Both preferred forms contain a low level of starch, which is a less desirable component of the fibre composition. In addition, the use of the stalks, which is a waste material from processing bananas, is particularly valuable with respect to adding value to waste.

The plant material can be diced in any manner with any dicing apparatus, for example a simple dicing machine or food-processing-like device can be used. It is preferred that the raw material is diced to from 2 to 20mm in size, more preferably from 4 to 10mm. While not wishing to be bound by theory, it appears that this size is optimal for retaining the structure of the plant cell walls and their components, which are the main constituents of the fibre product.

In an aspect of the invention, the raw material is subjected to a wash which may comprise hydrogen peroxide, cellobiase and xylanase. Any concentrations of these chemicals can be used. However, it is preferred that they are added at from 100 to 500ppm, more preferably at 200ppm. T'he chemicals can be added at ambient temperature, or the temperature of the mixture of raw material and chemicals can be heated. The mixture of raw material and chemicals is preferably heated for a period of time to assist in the cleaning action of the peroxide, and commencement of the digestive process by the enzymes. More preferably, the mixture of raw material and chemicals is 00 heated to about 70 0 C for about 10 minutes. The mixture can then be cooled to ambient 0 temperature, and filtered.

The diced material may be subjected to acid or alkali treatment. The acid or alkali can be any appropriate acid, for example citric acid, phosphoric acid, nitric acid; or any alkali, for example sodium or potassium hydroxide. Preferably, the alkali is sodium hydroxide, added as a solution in water. The acid is also preferably added as a solution in water. The solutions can be any useful concentration, but the solutions are 00 preferably from 0. I to 3.2% solutions.

SThe acid or alkali treatment can be at ambient temperature, or can be at elevated temperature. Preferably, the mixture comprising the diced material and the acid or alkali solution is heated for a period of time. More preferably, the mixture is heated to about 90C for from 2 minutes to 2 hours, then cooled to ambient temperature, and filtered.

In addition to xylanase, at least one other enzyme is added to this cooled and filtered mixture. The additional enzymes are preferably papain, cellobiase and cellulase. Xylanase is an enzyme which hydrolyses xylans (polysaccharides in plant cell walls); cellulase hydrolyses cellulose in plant fibres and is not found in humans; papain is a protein-cleaving enzyme derived from plants. Papain has a mild soothing effect on the stomach and aids in protein digestion. Cellobiase is a cellulase which is specific to cellobiose, a disaccharide from cellulose hydrolysis.

The enzymes can be added in any amount, but are preferably added from 0.1 to 5% of the dry weight of the mixture.

The mixture containing the enzymes can be held at ambient temperature, or can be at elevated temperature. Preferably, the mixture is heated for a period of time.

More preferably, the mixture is heated to 60'C for form I minute to 2 hours, then cooled to ambient temperature.

The final mixture is milled to a fine powder to give the dietary fibre composition of the invention.

In an alternative embodiment, the invention resides in a method for producing a powdered fibre material from plant material. The method is explained with 00 6 particular reference to the production of fibre from the banana plant including banana O skins, green bananas, ripe bananas, stalks and combinations of these. The pseudostem of the banana plant is a particularly preferred raw material.

In a preferred embodiment, the process includes the steps of Itn 5 i. collecting waste banana plant material; ii. size reduction of the waste banana plant material which can be achieved by crushing, chopping, cutting or dicing; 00 O iii. blanching the waste banana plant material in an ascorbic acid mix at approximately 3000 ppm which has been heated to 90'C and in which the war 1 0 material is soaked for approximately 3 minutes; iv. a water removal step which can be accomplished by draining, centrifuged in or pressing the excess water from the product using rollers for example; v. a drying step in which the intermediate product is dried for a period of time at elevated temperature of approximately 80 to 100C; vi. cooling the product to approximately 180 at which time the product has a moisture content of approximately 3 to 6%; vii. milling the intermediate product, preferably using a hammer mill to produce the size of the intermediate product to as low as approximately 50 to 80 P; and packing in moisture resistant transfer bags.

Not all of the above steps are required in all applications.

The above steps produce a fibre powder with a light tent colour and which is almost tasteless. The apartment yield ratio is 20:1. A typical banana fibre analysis per 100 g includes the following; Dietary Fibre Total 56.3% Protein 3.7% Fat 2.2% Carbohydrates 24.1% 00

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z 00 tq ©o Starch 21% Ash Potassium 7800 mg (approximately 1.5 times RDA) The process works best with the raw banana plant pseudostems, which have been approximately I to 2 inches above the level of the soil and below the level of the leaves. This pseudostem is normally a waste product on a typical banana plantation.

Some pseudostems may be up to 12 feet tall and have a circumference of approximately 18 inches.

As a result of the above process, contaminants such as fertilisers, chemicals, heavy metals and pesticides that might otherwise reside in the pseudostem are removed.

There may be a predecessor step utilising a washing process of the raw stem in order to remove any residual soil. The second step is typically a crushing step with crushing rollers which squeeze up to 90% of the water fromrn the stem. This process is typically assisted by prior size reduction of the pseudostem to small portions. The aim from the crushing process is to have an output of a semidry fibrous string like material is capable of being further size reduced and crushing to bring the water content to a level where the stringy mass feels dry to the touch.

The next step is typically one in which the stringy mass is cut into links to be moved into a vat of ascorbic acid prepared to approximately 3000 ppm with a pH of approximately 3.2 to 3.8.

The following step is one in which he ascorbic acid solution is heated and possibly agitated as the mass moves through the bathing steps (of which there are usually two). The masses treated by steam bathing or blanching avoiding oxidisation at this point.

The heat applied is approximately 82 to 900 to which they material is exposed for approximately 3 minutes.

00 There may sometimes be a Further size reduction step prior to a liquid O removal step in which the acid and water mix including any contaminants are removed from the intermediate product again to the point where the product feels dry to touch.

(Ni Typically a drying step follows in which heat is applied for approximately 2 hours at approximately 82.

A cooling step in which the intermediate product is cooled to approximately 18'C typically follows.

(Ni 00 0 The intermediate product is being preferably milled reducing it to a particle size of approximately 1.5 mm. The material is then further milled to reduce particle size to approximately .3 mm or 50 to 80 p depending upon the original pseudostemrn types and required output.

Without wishing to be limited by theory, the pseudostem contains water carrying cells and the above-mentioned process will typically target these water carrying cells and maintain their structural integrity whilst undergoing various size reduction and contaminant removal steps. By maintaining the water carrying cells of the pseudostem intact and present in a powder of approximately 50 to 80 p, the fibre powder has particular advantages. In particular, the ability of the fibre powder to assume a variety of aspects by adding different additives such as minerals, guarana, or flavouring. The process has been trialled on other plant materials such as wheat, Apple and citrus but it has been found that the fibres resulting from these raw materials take on or have leftover characteristics from the plant material used as a raw material. The banana pseudostem fibre is bland and has fewer leftover characteristics. The banana pseudostem fibre is also particularly stable with a good "mouth feel".

In order that the invention may be more readily understood and put into practice, one or more preferred embodiments thereof will now be described.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a stem and bananas as used in an aspect of the invention.

Figure 2 shows partially diced raw material (banana plant).

Figure 3 shows finished fibre composition.

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DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

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z Having broadly described the invention above, a non-limiting example of the dietary fibre, its synthesis, and its efficacy, will now be given.

Example 1: Preparation of the Dietary Fibre Stalks of the banana plant are washed with hydrogen peroxide, cellobiase and xylanase (200ppm). The mixture is heated to 70 0 C for 10 minutes. The mixture is then cooled to ambient temperature and filtered.

00 O The filtrand is diced into pieces of 4-10mm. The diced material is mixed C with citric acid aqueous solution) at 90°C for between 2 minutes and 2 hours, then cooled to ambient temperature. The material is filtered.

Xylanase, papain, cellobiase and cellulase of the dry weight) are added to the filtrand. The mixture containing the enzymes is heated to 60°C for between 1 minute and 2 hours, then cooled to ambient temperature, and filtered.

The filtrand is milled to a fine powder to give the dietary fibre composition of the invention.

Example 2: Comparative Bread Preparation The following results indicate the efficacy and attractiveness of the fibre composition of the invention.

METHOD

The following ingredients were used to bake two loaves of bread. Loaf A was prepared incorporating the dietary fibre of Example 1. Loaf B was prepared using conventional ingredients. Both loaves were baked under identical conventional conditions.

Ingredient Amount (LOAF A) Amount (LOAF B) White All Purpose Flour 784 1000 Yeast 25 Water 665 656 Salt 21 21 00 1 Sugar 50 O Milk 20 Shortening 40 SDietary fibre 106 Total 1711 1812

RESULTS

00 The resultant loaves of bread had the same mass, although Loaf A had IOOg less ingredients. This is beneficial because bread is usually sold on mass.

Loaf A had a more golden colour than Loaf B. The visual appeal of products such as bread is very important for sales.

Loaf A had less air pockets than Loaf B. This is also an important feature for sales.

It is clear from the foregoing that the invention provides a simple and efficient method of producing dietary fibre from fruit or vegetable material. In addition, use of the dietary fibre in edible products gives a superior product with known health benefits.

The foregoing embodiments are illustrative only of the principles of the invention, and various modifications and changes will readily occur to those skilled in the art. The invention is capable of being practiced and carried out in various ways and in other embodiments. It is also to be understood that the terminology employed herein is for the purpose of description and should not be regarded as limiting.

The term "comprise" and variants of the term such as "comprises" or "comprising" are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required.

Any reference to publications cited in this specification is not an admission that the disclosures constitute common general knowledge in Australia.

Claims

2. The method of claim I, wherein the plant material comprises fruit or vegetable material and particularly banana plant material.
3. The method of claim 1, wherein the plant material is waste from fruit or vegetable processing.
4. The method of claim 3, wherein the waste is banana plant stalks. The method of any one of claims 1-4, further comprising, prior to dicing the plant material: washing the plant material with a solution of hydrogen peroxide, cellobiase, and xylanase of from 100 to 500ppm; heating the washed material to from 50 to 100 0 C for from 2 to 20 minutes; and cooling the material to ambient temperature.
6. The method of claim 5, further comprising, after enzyme addition at step heating the crude composition to from 40 to 80 0 C for from 1 minute to 2 hours; cooling the crude composition to ambient temperature; and washing the crude composition with water.
7. The method of claim 6, wherein the plant material is diced to from 2 to 00 12 0 O
8. The method of claim 7, wherein the alkali is a sodium hydroxide solution O of from 0.1 to and the acid is citric, phosphoric or nitric acid solution of from 0. 1 to
9. The method of any one of claims 1-8, wherein the at least one other enzyme is papain, cellobiase, cellulase or a combination thereof. A dietary fibre composition when prepared by the method of any one of claims 1-9. 00 I I. A dietary fibre composition prepared from banana plant stalks.