AU2948892A

AU2948892A - Cereal extracts

Info

Publication number: AU2948892A
Application number: AU29488/92A
Authority: AU
Inventors: Roderick Norman Greenshields; Artis Llywelyn Rees
Original assignee: Unilever Bestfoods North America
Current assignee: Unilever Bestfoods North America
Priority date: 1991-11-16
Filing date: 1992-11-16
Publication date: 1993-06-15
Anticipated expiration: 2012-11-16
Also published as: WO1993010158A1; AU670420B2; AU2933592A; WO1993010157A1; RU2119758C1; TJ201B

Description

CEREAL EXTRACTS

This invention relates to a process for producing cereal extracts.

The use of corn bran extracts as bulking agents in 5 food products is well-known. US 4927654 discloses a process for producing hemicellulose extracts from delignified plant fibres, such as corn bran, by extracting the plant fibres with sodium hydroxide solution and acidifying the resulting mixture to 0 precipitate a first hemicellulose fraction. A second hemicellulose fraction is precipitated from the resulting filtrate by the addition of ethanol.

The present invention provides a process for producing 5 two novel extracts from cereal-derived material.

Accordingly, the present invention provides a process for producing a hemicellulose-based cereal extract comprising the steps of: 0

(i) milling cereal material;

( ii) suspending the milled material in an aqueous liquid; (iii) treating the resulting suspension with an 5 alkali;

(iv) lowering the pH of the treated suspension to from 5 to 7 ; and (v) separating the solid and the liquid in the resulting mixture. 0

The cereal material is preferably milled (either in wet or dry form) to a particle size of from 50 to 250 μm e.g., 80 to 180 μm. The aqueous liquid in which the milled cereal material is suspended is preferably c water but may also be a solution or a suspension of other substances in water provided that this does not adversely interfere with the subsequent steps in the process. The suspension preferably contains from 5 to 10% (e.g., 8%) dry weight/volume of milled corn bran 5 and may be formed at ambient temperature.

The cereal material is preferably cereal husk or bran and may be obtained from cereals such as maize, corn, barley, wheat, rice or oats, or malt or malt culms. -JO Preferably the cereal material is corn bran. The milled material may be air classified or sieved to removal starch and may comprise starch removed by suitable enzyme treatment, for example, with diatase (alpha- or beta-amylase) .

15

Many alkalis may be used to effect the alkaline treatment step (step (iii)) of the process e.g., metal hydroxides such as sodium and potassium hydroxides or metal carbonates such as sodium or calcium carbonate.

20 Preferably, potassium hydroxide (e.g., in the form of a solid) is added to the suspension to provide a concentration of not less than 4% w/v of KOH. The mixture may be stirred to dissolve the potassium hydroxide. This is accompanied by a colour change to

2 bright yellow or orange. The mixture is preferably heated to from 70° to 80°C for from V_ to 2 hours in order to effect maximum extraction or until a rapid increase in viscosity is noticed. The reaction mixture is then adjusted to a pH of from 5 to 7 (e.g.,

•3 neutral pH) with an. acid (e.g., dilute or concentrated hydrochloric acid). This may be accompanied by a visible paling in colour and "clouding" of the material. The extract is preferably separated from the insoluble material by filtration through a coarse 5 filter (e.g., grade 0 sintered glass at lab scale/5-50 μm plastic mesh on larger scale) with the application of partial vacuum or by centrifugation.

The insoluble material may be washed in situ on the filter with warm water to give the desired degree of extraction. Extraction by this process typically yields 45-55% of the dry weight of the material.

The extract may be purified in the following manner:

1 Extracts and washings are combined and diluted such that the total dissolved solids are in the region of 2.5% w/v.

2 The diluted extract is applied to a tangential flow ultrafiltration apparatus. (Under the following conditions during a pilot scale trial).

Starting volume 100 litres Membrane area 6 m² Membrane configuration parallel tubes Membrane type polysulphone 15,000 mwco Average flux rate 9 to 10 litres m^~2.h^-1 Run time 85 min

The concentrated retentate was diluted with 30 1 of water and the operation repeated three times before the solids content of the filtrate approaches zero.

Further decolourisation and deodorisation may be achieved by passing the diluted desalted filtrate over a carbon column containing Anthrosorb for odour removal and Norit C for colour removal.

The extract which at this stage is quite viscous may be dried by freeze drying, vacuum drying or spray drying. The extract is essentially an alkali-soluble complex hemicellulose mixture.

The extract may be used as a bulking agent or a thickening agent (e.g., in food products) and has adhesive properties.

A second cellulose-containing extract may be obtained by the following process. The extract may be produced as an insoluble bleached cellulose residue of alkaline extracted cereal material (e.g., cell walls of maize bran) and may contain other insoluble biopolymers besides cellulose.

In a further embodiment, therefore, the present invention provides a cellulose-containing extract produced by the process comprising the steps of:

(i) milling cereal material; (ϋ) suspending the milled cereal material in an aqueous liquid; (iii) treating the resulting suspension with an alkali; (iv) lowering the pH of the treated suspension to from 5 to 7;

(v) separating the solid and liquid in the resulting mixture, (vi) washing the solids; and (vii) drying the washed solids.

The insoluble material obtained from alkali extraction of the hemicellulosic material after step (v) may be resuspended in water to give a from 2 to 5%, preferably from 2.5 to 3.0% w/v, suspension in water. The pH is adjusted to 12.2-12.5 preferably by adding 40% w/v potassium hydroxide solution.

>^*¥ After raising the temperature (e.g., to from 70 to

75°C) in an indirectly heated vessel, hydrogen ? 5 peroxide (e.g., 30 vol or 10 vol) is added preferably in an amount such that the peroxide is present at an amount of from 15 to 20% dry wt/dry wt insoluble material. The temperature is maintained, with gentle stirring, at the elevated temperature (such as from 70 10 to 75°C) for from 2 to 5 hours (e.g. , 3-4 hours). Allowance should be made in the capacity of the vessel for up to 20% foaming on addition of peroxide. The suspension may be stored for some days at this stage without loss or damage.

15

Following the reaction with peroxide, the pH of the suspension is lowered to below 7 (e.g., from 5.5 to 6.0) with an acid such as hydrochloric acid. Solubilised material is preferably removed by

20 filtration under partial vacuum. (Grade 0 sintered glass filter on laboratory scale, 5-50 μm plastic mesh on larger scale).

The insoluble material may then be washed on the 25 filter with water, preferably with at least 3 volumes of water. The washed material may be stored aseptically , or suspended and spray dried.

This extract can be used as a bulking agent in 30 foodstuffs but also possesses lipomimetic properties.

The present invention thus allows the production of -_- both an insoluble polysaccharide and an alkali soluble polysaccharide which may be used as food ingredients.

Claims

Claims

1 A hemicellulose-based cereal extract produced by the process comprising the steps of:

(i) milling cereal material;

(ii) suspending the milled cereal material in an aqueous liquid; (iii) treating the resulting suspension with an alkali; (iv) lowering the pH of the treated suspension to from 5 to 7 ; and (v) separating the precipitated solids and the liquid in the resulting mixture.

2 A cereal extract as claimed in claim 1, wherein the cereal material is husk or bran.

3 A cereal extract as claimed in claim 1 or claim 2, wherein the cereal is corn.

4 A cereal extract as claimed in claims 1 to 3 , wherein the suspension formed in step (ii) contains from 5 to 10% dry weight/volume of milled cereal material.

5 A cereal extract as claimed in claims 1 to 4 , wherein in step (i) the cereal material is milled to a size of from 50 to 250 μ , preferably 80 to 180 μm.

6 A cereal extract as claimed in claims 1 to 5, wherein step (iii) comprises the addition of potassium hydroxide in an amount such that the mixture contains potassium hydroxide at a concentration of at least 4% weight/volume and maintaining the mixture for a time and at a temperature until a rapid increase in the viscosity of the mixture occurs.

7 A cereal extract as claimed in claim 6, wherein the mixture is maintained at from 70 to 80°C for from 1^₂ to 2 hours.

8 A cereal extract as claimed in claims 1 to 7 , wherein the separation in step (v) is effected by

10 filtration.

9 A cereal extract as claimed in claims 1 to 8 , wherein the process further comprises the steps of:

■J (vi) purifying the separated liquid; and (vii) drying the purified liquid.

10 A cereal extract as claimed in claim 9, wherein the liquid is purified by ultrafiltration and, 0 optionally, treatment with activated carbon.

11 A cereal extract as claimed in claim 9 or claim 10, wherein the purified liquid is dried by freeze drying, vacuum drying or spray drying. 5

12 A cellulose-containing cereal extract produced by the process comprising the steps of:

(i) milling cereal material; 0 ( ϋ) suspending the milled cereal material in an aqueous liquid; (iii) treating the resulting suspension with an alkali; (iv) lowering the pH of the treated suspension to from 5 to 7; (v) separating the precipitated solids and the liquid in the resulting mixture, (vi) washing the solids; and (vii) drying the washed solids.

13 A cereal extract as claimed in claim 12, wherein between steps (v) and (vi) the process further comprises the steps:

(a) resuspending the separated solids in an aqueous liquid;

(b) raising the pH of the resulting suspension;

(c) treating the mixture with hydrogen peroxide;

(d) lowering the pH of the mixture to below 7; and (e) separating the solids from the mixture;

14 A cereal extract as claimed in claim 13, wherein in step (a) the suspension contains from 2 to 5% w/v separated solids.

15 A cereal extract as claimed in claim 13 or claim 14, wherein in step (b) the pH of the suspension is raised to from 12 to 13 by the addition of potassium hydroxide solution.

16 A cereal extract as claimed in claims 13 to 15, wherein in step (c) hydrogen peroxide is added in an amount to give from 15 to 20% weight hydrogen peroxide/weight insoluble material and the mixture maintained at from 70 to 80^βC for from 2 to 5 hours.

17 A cereal extract as claimed in claims 13 to 16, wherein in step (d) the pH of the mixture is lowered to from 5.5 to 6.0 with hydrochloric acid. 18 A cereal extract as claimed in claims 13 to 17, wherein in step (e) the solids are separated from the mixture by filtration.