CA1069751A

CA1069751A - Gelling and thickening agents

Info

Publication number: CA1069751A
Application number: CA224,743A
Authority: CA
Inventors: Keith Buckley; Ian E. Burrows; John R. Mitchell
Original assignee: Mars Ltd
Current assignee: Mars Ltd
Priority date: 1974-09-04
Filing date: 1975-04-16
Publication date: 1980-01-15
Also published as: US3982003A

Abstract

Abstract of the Disclosure:
Food products comprising solid foodstuff and more especially meat, meat by-products or other proteinaceous materials are contained in an aqueous phase of near neutral pH value thickened or gelled by pectic substances having a degree of esterification (methoxylation) of less than 20%. Where a rigid gel is required the pectic substance is preferably reacted with a di- or tri-valent metal ion, notably calcium ion and also with a sequestrant. The pectic substance is a natural pectin source, for example citrus peel, in which the pectic substance has the required low level of esterification, for example by enzymatic or chemical treatment of the natural material. Food products employing the thickener or gelling agent of this invention include canned meat products containing meat or meat by-product pieces in a gel or thickened gravy formed by the pectic substance, meat loaf and similar products in which the gel forms a rigid binder for the meaty material, formed products such as sausage or simulated meat pieces based on vegatable proteins, and semi-moist products based on comminuted meaty materials in which the pectic substance provides a coherent elastic texture.

Description

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...... . ' The present invention concerns food compositions and provides products in which nutritious materials, including more especially meat or other proteinaceous materials, are bound together by or contained in a gelled or thickened aqueous phase.
A variety of gelling, binding and thickenin~ agents are used in the food industry, including seaweed extracts, gelatine, modified starches, caseinates, egg albumen, and galactomannan gums, to produce such products as neat loaves,~
canned hams and pet foods. However, these materials suffer the disadvantage of being derived froM raw materia]s of relatively low availability and in several cases the annual supply is subject to the vagaries of wind and tide. In addition the materials are often expensive, partially as a result of the elaborate puri~ication procedures employed in their manufacture In contrast, the raw material sources of pectin are abundantly available since pectic substances are present within the tissues of all green land plants and are currentl~ obtained rrOm a variety of waste product, e.g. citrus pulp and peel and apple pomace.
In particular, citrus peel and similar protopectin bearing sources are available in enormous quantities. For exa~ple, in 1972-3 the state of Florida, US~, alone produced .~
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some 600,000 tons of dried citrus waste, the maJority of which is used as an animal feed. This citrus waste results from the extraction of fruit Juice from oranges, lemons and other citrus fruit and consists of the peel and pith of the fruit, which comprises some 40 - 6~/o of the whole fruit.

Although a small proportion of the peel is dried and employed in the manufacture of high- and low-methoxyl pectins the major part is used as animal feed since no other applica-tion has been found for the material. Orange peel, in p ~ticular gives problems tc the pectin manufacturer in being difficult to filter and in posse~ising high levels of enzymes which attack the pectln ~olecule.
Some thirty years ago Wilson (U.S. Patent No. 2,132,065) disclosed a method of manufacturing a crude alkaline de-esterified pectate pulp but this product does not appear to have found any ,r~-.
significant markets and is currently not manufactured.

Pectic substances are complex colloidal carbohydrate derivatives that occur in or are prepared from plants. rllhey consist predominantly of polymers of cc-D-galacturonic acid, although small amounts of neutral sugars such as rhamnose, xylose and gu~ose may occur in the main polygalacturonic acid back'oone or as side chains. The carboxyl groups of the poly~ers may be esterified with methyl groups to a greater ~6975~ .

or lesser extent and unesterified groups may be partly or completely neutralised by one or more bases. ~he water-insoluble pectic substance that occurs in plants is known as protopectin and on restricted hydrolysis yields pectinic acids ?
which contain a significant proportion of methyl ester groups, and pectins, which are those water-soluble pectinic aci-ls that are capable of forming gels with sugar and acid under suitable conditions. Pectic acid is the term applied to colloidai polygalacturonic acids that are substantially free from methyl ester groups and are formed by substantially complete h;drolysi~
of other ~ectic substances.
The gelling behaviour of pectic substances depends critically on the proportion of the galacturonic acid residues which are methox~lated. In a completely esterified material esterified with methyl groups, i.e. with a degree of esterifica-tion (D.E.) of 100%~ the methoxyl content by weight is about 15,h.
Currently available commercial pectins used for gelling applica-tions can be divided into two classes:-1. High methoxyl pectins with a D.~. above 50%, which for~
gels of the traditional jam type. ~ectins of th;s type will only form gels at pH values below 3.5 and in the presence of substances which are believed to act to dehydrate the pectin molecule. Levels of sugar above g7~L

60% are generally employed for this function though the materials such as alcohol or glycerol could be used.
High methoxyl pectins are primarlly employed as gelling agents in preserves and confectionery foodstuffs.
So-called low methoxyl pectins in which usually between ~0 ~nd 40 per cent of the galacturonic acid residues are esterified. Pectins of this type can form gels over a wider range of pH values in the absence of sugar but require the presence of divalent alkaline earth ions.
~hey have greatest stability ih the pH region 4.0 - 4.5 especially when the pectin gel is subjected to heat treatment (see British Patent No. 814,549). Low methoxyl pectins have been employed as gelling agents in food products such as dietectic jame and fruit milk ... .
. 15 desserts. Commercial low methoxyl pectins are generally prepared from high methoxyl pectins either by treatment v with acids over a very long period of time or by the action of ammonia in alcoholic systems. In the latter case the resultant pectin product will contain some ? galacturonic acid residues in which the carboxyl groups have been amidated.
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In certain cases it is desired to form gelled or thiokened food products at near neutral pH values, which have been subjected to heat treatment in order to achieve pasteuriza-tion or sterilization. The texture of the gel required may range from a firm solid jelly to a viscous gravy. Such products will generally consist primarily of meat or fish but may also consist of vegetables or other foods. It has been found that it is not possible to form satisractory thickened or gelled ; canned products at such conditions of heat treatment and p~I by~
using either high methoxyl pectins or pectins which have metho~yl contents in the range 20 - 40%. It is believed that one of the reasons for this is that pectins of these types depolymerise at high temperatures and neutral pH values and thereby lose their gelling properties.
; We have now found that if pectic substances are employed that have less than 20,b of the carboxyl groups methylated, and preferably less than 10%, the molecule appears to have sufficient heat stability to retain its gelling or thickening p~operties in products at neutral or near neutral pH values after heat treatment. Such substances may therefo~e be used as gelling or thickening agents or binders in pasteurized, zterilized, canned or otherwise heat tre~tod food products, .,; , ~.

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For convenience, pectic substances having a D.E. below 20% will be referred to herein as "pectates", this term thus including not only the ideal case in which substantially no methoxyl groups are present but also pectinates with a D.E. below 20%. The preparation of pectates by cold alkaline hydrolysis of protopectin has been described by Wilson in United States Patent No. 2,132,065.
Aocordingly, this invention provides a food product comprising solid foodstuff and an aqueous phase, the aqueous phase having a pH value in the range of 5 to 8.5 and being thickened or gelled by a deesterified natural pectin source mRterial containlng at least 5% pectic substance having a degree of esterification below 20% and containing at least one non-toxic di- or tri-valent metal ion. Such compositions are usually heat-pasteurized or sterilized and may be contained in hermetic packages such as cans. They may exhibit the rigidity characteristic of a gel or the viscosity and, usually, pseudoplastic or thixotropic properties required of thickenel products, as described hereinafter.
The pectic substances useful for this invention are the crude natural pectin scurce~, cuoh as apple, citrus cr =ug~r }eet : : . .
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~10 source material or adding it to a substantially neutral fcod composition prior to pasteurization or sterilization may cause a reduction in the D.E. sufficient for the purposes of this ; invention.
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Thus if orange peel is ground to a small particle 1~ size, preferably neutralized to pH 7-8 with an alkali such as sodi~ carbonate, for example over a period of 30 minutes, washed to remove sugars and objectionable soluble compounds and dried, the ground product may be emploued as a thickeni~
and gelation agent in canned foods. Since the majority of the orange aronatic oonstituents and colour lies in the surface layer of the peel (the flavedo) it is desirable when using the processed peel to thicken or gel products such as meat or ~-~ - fish that the flavedo be removed prior to processing, thus , . .
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~Q~9751 lea~ing the less characteristically flavoured albedo Shaving techniques for removing the orange flavedo from the crushed orange halves are ~ell reported in the literature.
5 ~he reaction mechanisms by which the protopectin in the peel is converted into a gelling agent is not well understood. However, although this invention does not depend on any theory for its performance, one possible explanation is that enzymes liberated during the grindin~
10 of the orange peel at least partially demetho~ylate the pectin molecule, which is thought to be linked to he~icelluloses and other materials in the protopectin configuration, and hhat on subsequent heat treatment in the substantially neutral food - product further demetho~Jlation and solubilisation of the pectin occurs. We believe that the resulting pectate then ; reacts with alkaline earth ions in the food product to form a thickened ox gelled system. : :
It will be appreciated that any hydrolysis or other treatment of the pectic substance should not cause excessive reduction of its molecular weight, since this impairs its gell.ing and thickening qualities. We believe that if the de-esterification has been accomplished with an enzyme the : :
xesults characteristic of this invention can be achieved with .

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a higher D.E. than if de-esterification is accomplished by other means, presumably as a result of the sequential nature of this type of hydrolysis as opposed to the random removal of methoxyl groups along the chain when acid or alkali hydrolysis is employed. This is especially noticeable with more severe heat treatments, as in the retorting of canned products, and it may be surmised that the extent of depolymerisation of the pectate under these conditions is less in the case of enzyme de-esterified material.
Determination of the degree of esterification may be carried out by the measurement of the methoxyl content of the material and measurement of its galacturonic acid content.
Although a modification of Hin~on's saponification procedure is commonly employed to measure methoxyl content of high methoxyl pectins we have found this technique can produce inaccurate results when the samples under examination are crude protopectin sources, presumably as a result of interaction with other com-ponent5 of the source material, such as protein.
We have used both the modified saponification method and a more specific procedure based on gas solid chromatography along the lines suggested by Krop et al (Lebensm. - Wiss.u.
Technol, vol. 7, 1974, no. 1). Both methods have produced similar results for crude protopectin sources of low methoxyl content, i.e. the preferred material of the invention.
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10~9751 Modified Sa~onification Method:
A sufficient sample of finely ground dried material usually 2g., to release a maximum of 0.02g methanol) is stirred with 250 ml water and heated on a boiling water bath for 20 minutes with occasional stirring after which the mixture is macerated with a high speed stirrer. The dispersion is cooled to 20C and neutralised to pH 8.4 using a pH electrode to detect the end point, and N/10 sodium hydroxide to effect the neutralisation. 20.00 ml of N/lO NaOH is then added and, after stirring, allowed to stand for 20 minutes. 20.00~
N/lO HCl is added and the excess HCl estimated by titr~tion with N/lO sodium hydroxide solution to a pH 8.4 end-point using a pH electrode to detect the end point. ~itre = B ml.
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% methoxyl = B x 0.3104 -Weight of sample - ~ ~, ' -GSC Method: -

2 g. of finely ground dried material is stirred ~ith 100 ml water and heated on a boiling water bath for 20 minutes with occasional stirring, after which the mixture is macerated in a high speed stirrer. ~he dispersion is cooled to 20C-and 20 ml of a ~N sodiu~ hydroxide solution is added with stirring. After 20 minutes at 20C, 5 ml of 50% concentrated hydrochloric acid is stirred in and quantitatively made up to ." ' ' ' .
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200 ml with distilled water. The dispersion is allowed to stand for 10 minutes for the precipitate to settle.
The methanol content of the supernatant liquid is then determined gas-chromatographically using a similar condition to that described by Krop et al (loc. cit.) The galacturonic acid content of the sample is measured by repeàting the procedure described above up to and including the stage of standing for 20 minutes with 1N sodium hydroxide after which 20 ml of concentrated hydrochloric acid is added with stirring. 800 ml of propan-2-ol is added and the dispersion allowed to stand for 30 minutes.
The precipitated solid is f ltered off on a Buchner funnel and washed thoroughly with 60% by volume propan-2-ol in water. The solid is then dispersed in water, 10.0 ml 0.1N
sodium hydroxide is added and the solid dispersed using a high ; speed mixer. The dispersion is titrated to pH 8.4 with ~.1N
sodium hydroxide using a pH meter (~itre - A ml).

- % galacturonic acid = (A + 10) x 0.9707 weight o~ sample ¦
% degree of esterification = % metho~l content x 625.5 % galacturonic acid content ,; , .
. , .,' 1~ ' , ~9751 Pectates are usually obtained as the alkali metal salt, a~d it is usually necessary for a salt of a di- or tri-valent metal to be present in the food product along with the pectate i a satisfactory gel is to be obtained.
.uch metal ions may not be necessary where only a thickening action is required, and addition of such an ion may be avoided where a metal ion is present naturally in the food product or iD the pectin source or pectate itself. The preferred metal ion iscalcium, and suitable salts for addition to the product include di-calcium phosphate dihydrate, calcium sulp~ate dihydrate, calcium citrate, calcium lactate and calcium chloride.
We have found it desirable for a sequestrant or chelating agent to be included in the product formulation, particularly where a crude protopectin source is emplo~ed, where the pectate is in the form of a di- or tri-valent metal salt or where the product naturally contains high levels of divalent or trivalent metal ions. Suitable sequestrants include sodium tripolyphosphate, sodium hexametaphosphate and trisodium citrate. Such a chelating agent will serve ~delay the formation of a gel-, permitting easier handling of the cold mix and filling, for example, into cans, and also more rapid heat penetration during pasteurization or sterilization. When meats are present an alkaline chelating will also help to .

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; counteract the decrease in pH wh-ich has been observed on ; the addition of di- or tri-valent salts to meats. ~his development of acid condition.s can also be counteracted by the addition of an alkali, such as sodium hydroxide, or an alkaline buffer.
; The amount of pectate or crude de-esterified pectin source required to form a thickened or gelled food product may vary widely. When a pure pectate is employed this may be ; present at from 0.1 to 10% by weight of the food product, bu~
~r~ 10 preferably from 0.5 to 2.0%. When a crude de-esterified pectin source is employed the level of suc~ pectin source (on a dry basis) may range from 0.1 to 20% by weight of the food product, but preferably from o. 50/o to 3%. The crude de--esterified pectin source should contain more than 5% pectin (and preferably more than 10% pectin) on a dry matter basis.
The crude de-esterified pectin source may be used in the dried form or when, for example, the user site is conveniently close to the processing station, may be used ~-- without drying" when the quantities required will depend on the solids content of the crude de-esterified pectin source.
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In accordance with the prefe-red aspect of this invention, we have found that de-esterified citrus peel is . .
surprisingly ef~ective for gelling and thickening. For .. .
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example, we found that a rneat product gelled by means of ; - 1.5% by weight orange peel was firmer than a similar product gelled with 1.0% pure pectate. This was surprising because analysis showed that the orange peel contained only 3~o pectin (expressed as galacturonic acid). The orange peel may be subjected to alkaline de-esterification but we have found that this is not an essential step for the purposes of this invention.
The dried processed peel contains some 20 - 45,b pectin (expressed as galacturonic acid), depending upon the fruit type, degree of maturity, variety, and other factors, and the remaining dry solids comprise hemi-celluloses, araban and other ballast materials. Recent nutritional thinking &
tends to the view that such cellulosic materials in the quantities contributed to the diet by such inclusion are distinctly beneficial to health. ~ further advantage of the use of crude materials such as processed peel in accordance with the invention lies in the low calorific value of this material which, together with its previously described properties, signifies its useful application in sli~ming and diabetic food stuffs where processed peel may be employed to obtain the required wa~er bindin~ properties in place of calorific water bindin~ agents s~ch as starch.

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` 1(~69751 ~hilst a variety of food ~aterials, such as ~egeta~le, fruits or sauces, can be thickened or gelleZ
- by the use of pectate or processed protopectin materials it is particularly advantageous in the case of canned meat products where the presence of the insoluble non-pectinaceous materials from the crude material, such as comminuted peel, is masked by the meat fines resulting from the heat coagulation of soluble meat proteins.
A most useful property in certain gelation systems is that of thermoreversibility. A thermoreversible gel can for present purposes be defined as a gel which has a melting point and setting point within the temperatures encountered in the preparation and utilisation of the gelled system.
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~` It has been found that the melting point and setting ~5 point in ~ccordance with the invention of pectate gels can be adjusted by increasing or decreasing the available calcium or other non-toxic di or trivalent metal ion content within the .
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food product. The availability of the calcium or other metal to interact with the ~ectate depends not only on the amount of calcium or other metal present but also on the type of metal ~;; salt employed and the type and quantity of sequestrant present in the system~
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Thus, at high levels of available calcium, food structures can be formed which æ e stable to heat processing whilst at lower levels of available calcium thermDreversible gelled or thickened systems can be obtained.
; We have also found that a thickened food product, i.e.
one in which the aqueous phase has an increased viscosity, can eit~r be produced by the direct use of relatively high levels of crude pectate sources or advantageously by the use of much lower levels ` of the crude pectate source in the presence of addRd calcium ions and sequestrant. m ese lower levels æ e at such a concentration that a coherent gel structure cannot form but instead viscous and usually pseudoplastic solutions are produced.
We have further found that if psyllium seed husk or gum is added to food product mixes containing treated orange peel an ; unexEected synergistic interaction occurs during the heat processing stage and producing in the finished product a fir-mer, tougher, more elastic gel structure than is obtained with either syst~m separately.
Psyllium seed husk and gum is derived from a group of plants belonging to the Plantago genus and is used in various pharmaceutical applications.

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Although we hav~ found citrus peel particul æ ly useful in the application described, other sources of protopectin, for example apple or pe æ pomace, or sug æ beet residues, æ e also useful for the pu~poses of the invention.
The invention also provides a method of making a food product comprising the steps of: ~a) preparing a mL~ of solid foodstuff and a deesterified natural pectin source material conta mlng at least 5% pectic substance having a degree of esterification belcw 20~, said material being dissolved in an aqueous phase having a pH
value of from 5 to 8.5; and (b) causing said pectic substanwe to react with a nontoxic divalent or trivalent metal ion to form a gel in said aqueous phase, whereby to produce a gelled or thickened food product.
This process can be carried out with a variety of . - ~
foodstuffs and in a varietv of circumstances. ~or example, pectates may be employed in the production of food products in sealed packages or containers, for example cans. Such products include hams, meat loaves and pet foods, notably for dogs and cats, and also foods - comprising a thickened aqueous medium such as sbews and soups.
Although depending upon the available calcium content the pectate gel may melt belcw the temperature of retorting of the cans, the pectate medium retains its gelling properties and æ ts again on cooling.

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Pectate~ can also be used as binders to provide a firm texture in manufactured products such as sausages and the fillings of meat pies. Such products do no~ attain as high a temperature as canned foods in processing but are sub,jected to at least pasteurizing conditions. Pasteurization can be defined as the application of sufficient heat, usually at temperatures below 100 C, to effectively eliminate vegetable bacteria, whilst sterilisation is the application of heat at temperatures above 100 C to effectively eliminate both ve~etable bacteria and spores.
Further examples of the use o~ pectates as binders include the production of simulated meat or formed meat pieces which are capable of retaining their integrity, for example, when included in a canned product. Such prcducts can be 15 ~ prepared by shaping, as by extrusion, a mix of com~inuted meats or meat by-products or vegetable protein together with the pectate material and desirable sequestrant. The product may be after-treated ln a solution of alkaline earth ions.
Pectates can also be used as binders in semi-noist foods, i.e. those stabilized by the inclusion of sufficient water soluble solutes to reduce the water activity to bet~een 0.65 and 0.85 and including an anti~ycotic.
~he preferred formulations of products incorp~rating a pectate gel or thickener embodying this invention depend on the particular type of product under consideration.
In the ca.se of canned meat or meat by-products the preferred formulations include (by ~eight) 20 to 95% meat or , . ~, ,, : ~: ''' ' 1~697~ii ~ , .
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meat by products, 0.1 to 5~o pectate (or 0.1 to 10%
comminuted citrus peel on a dry basis), 0 to 5% acceptable non-toxic a~kaline earth metal compound, 0 to 5% sequestrant . ,.
and 0 to 50% water (or 50 to 95,~ moisture content in the -~ 5 product)~
Ir the case of formed meat products?including sausage, prepared by binding together comminuted meats or meat by-products, the preferred formulations include ~.:
- 40 to 95% meat or meat by-products, 0.1 to 5Y pectate (or O ~1 to 10Yo com~inuted citrus peel on a dry basis), 0 to 5%
~; a~ceptable alkaline earth metal compound, 0 to 5/o sequestrant and 20 to 50% water (or 50 to 95% moisture content in the product).
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~- In the case of simulated meat pieces produced from ,. . . .
non-meat, e.g. yegetable, proteins? the preferred formulations include 5 to 50% vegetable prot~in, 0.1 to 5% pectate (or . , 0.1 to 10% comminuted citrus peel on a dry basis) 0 to 5'~o acceptable alkaline earth metal comnound, 0 to 5% sequestrant and ., .
20 to 50C/o water (or 50 to 95% moisture in the final pieces).
The following are exanples of the practice of this invention, as applied in a variety of near neutral products and demonstrate the stabi~ity of the gelling or thickening ~ agent to hot processing. All parts and percentages are by .; . .
weight unless the context otherwise requires.
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~ , ' Example 1 Use of fresh commLnuted orange peel:
(a) Treated orange peel was prepared as follows:-5.2 Kg South African navel oranyes were passed through ascraping machine to rem~ve the flavedo. The~ were then halved and pressed to remDVe the juice. The resulting peel ~3.45 Kg) was passed through a min oe r fitted with a 3/16" plate. The ground peel was washed with 2 litres of tap water and pressed in a muslin bag. 4.16 Kg of the washed orange pulp was obtained. m e pH of the treated peel was 5.2.

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(b) Preparation of a gelled meat product:-Formula Chopped lung 150 g.
~eat offcuts ` 150 g.
l~'ater 37.5 g-Sodium tripolyphosphate 6.25 g.
Calcium sulphate dihydrate (finely ground)5.00 g.
Treated peel 150 g.
The ingredients were mixed in a bowl and sufficient sodium carbonate (ca 0.4 g) was added to bring the pll of the mix to 7.5 and allowed to stand for 2 hours to reduce the D.E
of its pectin content to less than 20%. The mixture was then filled into cans, sealed and sterilized at 24 psi for 50 minutes.
After standing overnight the cans were opened and found to con-tain an integral meat pack comprising meat pieces suspended in a firm, brittle, clear jelly. The product pH was 6Ø
Example 2 Use of dried orange peel:
(a) The dried pulp was prepared as described in Example except that following washing and pressing the ground peel was dried in a laboratory fluid bed drier at 60C. Drying proved difficult due to the adhesive nature of the ground peel and it too~ several hours to dry. The D.E. of the dried peel's pectin content was less than 20%.

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(b) Preparation of a ~elled meat proAuct Chopped lung 15,b Siuulated meat 1~/o Meat offcuts 22.5%
Tripe 2.5 Ground bone 5.~/o Sodium tripolyphosphate 1.25,' Calcium sulphate dihydrate 1.0%
Treated peel 3.0%
Dye solution o.~%
Caramel 0. 5%
~ater 38.95~o The ingredients were mixed together, filled into cans, sealed and sterilized in an autoclave at 24 psi for 1 hour. After standing over~i~ht the product was found to consist of a firm meat pack containing pocke~s of a firm ~ -brittle jell7. Little or no orange aroma or taste w~s evident. mhe product ?H was 5.85.
Exa~le 3 Use of al~ treated orar.~e ~eel: -(a) 11.56 Kg of whole Californian oranges were scraped to remove the flave~o, halved and pressed to rer~ve the fruit juice. The 4.91 Kg peel obtained was passed through -- _ r ", ' : ' ' ~ ' a mincer fitted with a 3/16" plate, washed with 3 Kg water and pressed.
2.5 Kg water t~as added to the pressed peel and the pH was adjusted to 8.5 by the addition of 55 g of sodium carbonate. The slurry ~as allo~ed to stand at room temperature for 18 hours and then pressed in a muslin bag. The de-watered peel ~tas then dried at 60C in a fluid bed drier and coarsely ground. The pectin content of the treated peel was 1~/o. The alkali treatment was found markedly to assist de-watering of the peel.
(b) Preparation of a ~elled meat product Chopped lung 14.1,b Fibrous meat 7 . 8%
Simulated meat 7.0%
Offal;méat 3.9~o ; Ground bone 5. 7%
Meat offcuts 12.0%
Tripe 7- 3/
Water 9 9/
Sodium tripol~phosphclte 1. 1,b Calcium sulphate dihydrate 0. 9~o Caramel 0.4~io ) Dye solution 0. ~h ) ~reated peel - 2. 7% ) Gra~J
Water 25. 7% ) ,.

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The treated pee~ was mixed thoroughly with the cararr.el, dye and water and then added to a mi~ of the other ingredients. After thorcugh mixing the product was filled into cans, sealed and sterilized at 24 psi for 1 hour.
After standing overnight the product was found to consist of an integral, fir~ meat pack with pockets of clear firm brittle jelly. The product pH was 6.6.
E m_le 4 Use of al!ali-treated ora~ge ~eel with reduced calcium and 19 seaucstrant le~els:
The dried alkali treated orange peel, described in F,xample 3, was used in the following meat mix preparation:
Chopped lung 20,6 Simulated meat 10~h , Meat~,offcuts 20%
Tripe 5%
Ground bone 5%
~ater ' 5C~o Calcium sulphate 2H20 0.25ch Treated peel 2.0,~ ' Gravy:
. Sodium tripcl~phosphate 0.5,o Cara~el 0.5%
Dye solution 0.3%
Treated peel 1.0~o Water 30.~5,Co ', ' . ' ' , ,' , , ' _ 25 _ . .
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. . ' ': . ~, ; " ' -- `--~6975i The gra~ was prepared by Mixing the gravy in~redierlts, other than the treated peel, together and heating to 90C and then adding the trcated peel with vigorous stirring. After 3 minutes the viscous gravy was added hot to the meat mix and mixed thoroughly.
The product ~iY. was filled into cans, sealed and autoclaved at 24 psi for 1 hour. After standing overnig,ht the appearance of the product was found to be similar to that described in Example 3.
Examp]e 5 Use of alkali-treated oran~re ~eel as a thickener with no rent:
The dried alkali treated orange peel described in Example 3 was used in the followin~ meat mix preparation:
Chopped lung 305' Ground meat 30%
Water 10,b Gravy:
Treated peel 35' Caramel 0. 550 Dyestuff solution 0. 350 Water 26.20~?

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~06~7Sl The treated peel was added to the cold water, which - co~tai.ned cara~el and dyestuff solution~ and after 3 minutes mixi.ng the resulting slurry was mixed with the meats and remaining water. The mix was then filled into cans, sealed and autoclaved at 24 psi for 1 hour. After standing over-night the product was found to be a non-integral pack consisting o~ swollen meat chunks suspended in a viscous thick glossy gravy The product pH tlas 6.3.
Examnle 6 Use of dried l~ali-treated oran~e Peel ~ith seauestrant -but no ad(i~d calcium ions:
The dried alkali-treated orange peel described in : Example 3 was used to prepare the following meat mix:
Chopped lun~ 30,S
Ground meat 30C~b Water - 20C,b ; Treated peel 2,' - Grav~ mix:
Dried ground orange peel - 1,~
Sod.iu~ tripol~phosphate 0.25~o Caramel 0.5%
Dyestuff 3~
Water 25 . 95b ~ ' .

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The gra~3 mix ingredients were ni.xed and brought to the boil, and then added to the meat mix. After further nixing the mixture was filled into cans, sealed and auto-claved at 24 psi for 1 hour. After standing overnight the j product was founl to consist o a firm integral meat pack containing pockets of a clear soft brittle jelly particularly on the pack surface. The product pH was 6.5.
Exam~le Use of dried, alkali-treated ~ra~efruit peel:
South African grapefruits were hal~ed, squeezed to remove the julce and ground in a mincer fitted with a . ~ , . .

- 3/16" plate. The 814 g of ground peel so obtained was washed with tap water and pressed to remove excess water1 500 ml.of water was added to form a slurry and its pH was adjusted ro~ 4.6 to 8.5 b~ the addition of 11 g of sodium carbonate. The slurry was allowed to stand at room .
temperature for 18 hours and then pressed free of excess liquid, washed once with tap water, re-pressed and then dried in a fluid bed air dricr at 60C. The treated peel, having a pectin content with a D.E. below 2~, was ground to a fine powder and used in the following meat mix:-.'' ' " ' ' ' .
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Chopped lung 25%
. Ground meat - 15%
Fibrous meat 10%
Meat offcuts 10%
Water 10%
Sodium tripolyphbsphate1. 25/~o Calcium sulphate dihydrate 1.0 ,~
Graw:
-Treated peel 3.0%
Caramel 0. 5~o Dye solution 0.3%
Water 23 . 95%
The trcated peel was dispersed in the cold water containing the caramel and dye solution and this 'gravy' was added to the;~ther meat ~ix ingredients with thorough . mixing. The mix was filled into cans, sea~ed and auto-claved at 24 psi for 1 hour. After standing overnight, the product was found to consist of a firm, integra~ pac with a surface layer of a soft, brittle jelly. ~he product p~ was 6.2. The product had a meaty aroma with ..
only slight overtones of grapefruit. . :~

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Exam],e_8 Dried le~on peel was prepared from South African '~ lemons in the sa.me manner as described for grapefruit in "' Exanple 7. A meat product, prepared using the drled lemon peel in the sa~e manner as described in Example 7 , ~as found ~ to consist of a firm, integral ~eat pack with a surface layer .- of soft, brittle jelly. The product pH was 6.2 and it had - a. slight aroma of lcmons.
Exam~le 9 , 10 Use of ora~ eel with s~llium seed husk Dried orange peel was prepared as described in ~" Example 6 except that a drying temperature-of 90C was ..
employed. Powdered psyl ium seed hus'r~ was purchased from .. . .
a cornmercial sourcje. These materials ~ere used to prepare the,following gelled meat product:
. Meat mix:
'~' - Formed ~eat ' 3 . 7Yo - Textured vcgetable protei.n 26. 3%
. . Ground bone 9.3Yo , 20 , Meat offcuts 13.8C~o . Tripe 9- 3Yo ~dded water ' 4. 7~o Calciu~ sulphate dihydrate 0.3%
'Psylliu~ seed hus~ 0.5%
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c`Jra~ nix Dye solutiGn 0.5%
Caramel~ 9~
Sodium tripolyPhosPhate 0.5%
. 5 Water29.1~
Treated peel 1.0%

.~ The various lngredieIIts of the meat mix were combined together, and the gravy mix after being heated to 95C was added and mixed in thoroughly. The mixture was ., .
filled into cans and sterilized at 24 psi for 1 hQur. After . cooling and standing overnight the product was found to consist of a rigid meat pack embedded in a firm, tough - elastic gel.

. The product gel was firmer and tougher.than those obtained when using either psyllium seed husk or treated `. orange peel separatel~.

. Exam~le lO
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`.` (a) PreParation o~ treated oran~e peel.
i .
10 Kg of South African Navel oranges were halved, 20 squeezed to remove the juice an~ then passed through a mincer fitted with a 3/16" plate. The ground peel was : . washed with tap water, pressed, slurried in water and sufficient anhydrous sodiu~ carbonate was added with mixing :' .

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to raise the pH to 9Ø The slurry was allowed to stand . for 18 hours and was then pressed, washed, pressed and .~ ro3.1er dried. The roller dried flakes were ground lnto a fine powder. The yield was 520 g. and the D.E. of the pectin content below 2~,'.
; (b) U ~ in formed meat Pieces.
. - .
Formulation:
; Treated peel 1.6%
Water 31.7%
Sodium tripolyphosphate 0. 2%
; Non-fibrous meat offcuts 63;3%
- Dye soluticn 1.3% ~
Caramel 1. 9%, . ~ .
- ;. The sodium tripoly?hosphate, dye and caramel :-15 were. dissolved in the water which had been raised to boiling . point. Treated peel, prepared as at (a) above, was added : with vigorous stirring and the solution was intimately ~.
;. mixed with the non-fibrous meat. The mixture was extruded in ball-shaped pieces into a.10o calcium chloride solutlon and 20 allowed to stand for 4 hours.
The firm pieces were then removed, washed in water and autocl.aved in cans at 24 psi for 1 hour in the presence of minced meats.
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After being cooled, the contents of the can were ex~.~li.ned and the formed meat pieces were found to .. i have the fir~.ness and internal texture of lung.
.. ExamPle 11 ., .
Use in sirulated meat l)ieces.
Formulation:
Water 65.3,~
Caramel 2.~/o . Dye solution 1.5% .:
,~ 10 Sodium tri.polyphospha.te 0.'~/o Devital wheat gluten 28.~/o : ~reated peel 2.6%
.: The caraAmel, dye solution, sodium tripoly~hosphate ;
.. ~ and treated peel (prepared a.s described in Exa~ple 14), was heabed in the water to boiling point and the devital wheat gluten was added with vigorous stirring.
. The mix was poured into a tray and allowed to cool.
After standing for one hour the solidified mass was cut into ~-" pleces and processed with gelling agent solution in cans :~. 20 . at 24 psi for 1 hour.
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After bein~ cooled the simulated meat pieces were found to have retained their shape and to have a fir~ but rather brittle texture similar to that of cooked kidney.
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~ 0 69 ~ This-e~ample de~onstrates the usefulness of i .
- treated peel in binding together denatured protein materials, which possess no ag,regation ~roperties, into a coherent mass.
Exam~le l2 Use in fish/meal loaf ~roduct (a) I'hole Spanish Valencia oranges were scraped to ,~ remove the flavedo, halved and pressed to remove the fruit ; juice. 1 Kg of the albedo obtained was passed through a '~
mincer fitted with a 4 mm plate and mixed with 12 g. of "~ anhydrous sodium carbonate for 30 minutes. The albedo was , pressed in a muslin bag and then mixed, for 5 mlnutes, with an equal weight of water. This was then re-pressed in a muslin bag and after mincing through a 2 mm plate the albedo : . . ~ . . .was dried on a roller drier operating ar 80 psi. It was , obse'rved that roller dried material was much more bland in flavour and less yellow in colour than hot air dried ~aterial.
The D.E. of this naterial was 10C,b.
(b) The treated peel was then used as an alternative gclling agent for compa~ison with a cereal binder in a fish/
'. meat loaf product.
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:, f,' t,ereal Forznulation Meat byproducts 92 parts Whitefish 370 Poultry byproducts 186 Cereal 375 ^ - Brine . 63 .. - . . Whole blood 322 ~ Water 77 :~ .
Cod liver oil 26 ' 10 Milk protein source 65 Dye solution 19 Caramel 7 Treated Pe~1 Formulatlon Meat byproducts 92 parts .;.. . 15 Whitefish . 37 Poultry byproducts 186 :.:., .,.~ , .
. Treated peel 94 Sodium tripolyphosphate 10 . Whole blood322 Water 1051 . Codliver oil 26 ,... .
~: Milk protein source 65 .. Dye solution 19 Caraz3el 7 .. ~ .
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In each case, the ingredients were mixed to~ether, heated to the boil and held at this temperature for 5 minutes. ~he mix was filled into cans, which were then seamed and sterilized in an autoclave.

, 5 ' After being cooled the cans were opened and the products compared. The treated peel formulation product was found to be an integral meat loaf pacK similar in firmness ' to the cereal formulation pack but with an improved aroma and appearance.

Example 13 .
' This example is intended to demonstrate the relation-.
," ship between the degree of esterification of treated peel s~pl~
. . . . .
and their ability to produce thickened gravies after heat sterilisation. ,Three sa~ples of treated orange peel were . . ~. , . .~ .
1,5 prepared as described in ~xample i2 except that in the first .; sample no sodium carbonate was added, in the second 10 ~. , ' sodium carbonate was a,dded and in the third 15 g. sodium ,",, " carbonate was added to the' orange albedo after mincing,.

' The degree of esterification of'the three sa~ples ; , . . . was determihed as previously described and the following '," results obtained~

Sam~le De~rce of Est~rification , ~ . , .

106975~
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Oven baked~ formed meat chunks were prepared from , ': meat offals and binding agcnts according to formulations and procedures commonly employed in the food indust~y. Three gravies were prepared using the 3 treated peel samples by ~` heating to the boil the ingredients of the following for~ulation Treated peel 0.7 parts Caramel 1.6 ~ -' Dye solution 1.1 Sodium tripoly-phosphate 0.5 3 Water ~ 96.1 ,` 45 parts by weight of the formed meat chunks and ,' 55 parts by weight of the appropriate gravy were mixed ,' 15 together, filled into cans, sea-red and sterilized in an - autoclave. After cooling and opening the products were examined subjectively and in addition objective viscosity - measurements were ~ade on the product gravies.
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;' 20 Sam~le A~pearance Visco~ity b,~r Brookfi~ld ' Visco~-~e~*~lT
'' ' ' moclel ~in~
`,' s?eed 1 2 1 Formed,meat chunks in a lar~e `' 5 volume of watery brown liquid . 100 cps . .
- 2 For~ed meat chunl:s in a moderate volume of viscous bro:rn liouid 1225 cps 3 For~ed meat'chun~s in a low volume ' of very viscous brown liquid 1750 cps - * Trade ~rk , - 3~ -r--~06975~

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Ex~ml-~ e_14 Use in (Pel~ed meat products The three samples Or treat,ed orange peel described in ~xample 13 were used to compare l;heir ab~lity ln the preparation of gelled meat products.
~:- Product ~`ormula Formed meats 26.2 parts . Textured vegetable protein 2,4 . Tri.pe 8.5 Beef offal 19.3 Ground bone .4.5 . : Water 7.1 Gravy , 31.7 .: - :
' ~ . Grav~ Fornula :, Trea~ted peel 4.7 parts ~; Sodium tripolyphosphate 1.6 . ' Dye solution .' 0.8 , ., ~ .
.~i CaraMel 1.1 : . .
... Water 90.6 ~ .20 . Calcium hydroxide 0.3 ..... ..
~ Potasslum chloride 1.0 "'- ' - .
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` 1~)69'7Sl The gravy ingredients were mixcd toGether and heated to the boil. The appropriate quantity was then mixed with the other ingredients and the mixture fillcd into cans, seamed and sterilized in an autoclave. Af~er being cooled the cans were opened and the appearance noted:~
Sample Product A~earance ; 1 Very soft pack, collapsing on re~oval from the can, consisting of Meat pieces in a thin watery gravy.
2 Firm integral pack with a clear glossy firm gel.
3 Similar to Sample 2 except that the gel was slightly firmer.
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Example 15 15 Use in sausa~es ~
~ Beef sausages were prepared uslng a conventional - rusk component and also with this component replaced with a solution of treated peel (Sample 2 in Example 13~ and sodium tripolyphosphate according to the formulations given below:-2~ Standard Treated Peel Beef flank 56. 25C,b 56. 25~o Water 25 . ~b . 39 . 34C~b Rusk 1~ . 75/~o _ - Treated peel - 1.4~' Sodium tripolyphosphate - 2.94-S~
Seasoning To taste To taste .: .
: .

., r ' , In order to prepare the sausages the beef flank was coarsely minccd before bowl chopping, in the standard : ex~mple, with the water and rusk to a coarse paste. ?~n the treated ~ecl exa~ple the treated. peel and sodium .~ tripolyphosphate was heated in the water to the boiling point and then cooled to room temperature, before bowl choppi.ng with the meat to a coarse paste, The mixes were . stuffed into a sausage s'~in and links prepared.

. After frying in fat for the same temperatur~ and .
time it was found that the treated peel sausages were firmer, uicier and had much more meat flavour than the standard rus sausages.

.~ EY.ample 16 Use in Semi.~Moist Dog Food Formula~ion A: Meat offcuts ?5.8,' :i~ Su~ar 31.0%
?
. Water 12.6Yo Glycerol monostearate 0.4C~o . . Beef fat - 6.4,~
Citric acid 0.2,' - Butylated hydroxyanisole 0.0~/o Propylene glycol 3.9%
Dye solution 0.1Yo .. . .

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B: Treated pecl as Example 14 1~.9~o ; Sodium tripolyphosphate 1. 3~/o Dicalcium phosphate 3 . 6%
Potassium sorbate 0./~' ~ Vitamin supplement 1.~o .. . .
- The ingredients of the 'A' mix were mixed together and heated to boiling ?oint. After boiling for 10 minutes the mix weight was adjusted to the original weight by the addition of boiling water and the mixed ingredients of the 'B' mix were added with vigorous stirring. l~he entire mixture was then placed in a tray, a]lowed to cool, cut into chunks and sealed into plastic bags.

'`; The product had a pH of 6.5 and a firm, chewey texture and a pleasant meaty flavour without the usual unpleassnt soya aroma and taste which are present when in conventional products soya grits and flour are used to - achieve the blnding effect.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of making a food product comprising the steps of: (a) pre-paring a mix of solid foodstuff and a deesterified natural pectin source mate-rial containing at least 5% pectic substance having a degree of esterification below 20%, said material being dissolved in an aqueous phase having a pH value of from 5 to 8.5; and (b) causing said pectic substance to react with a non-toxic divalent or trivalent metal ion to form a gel in said aqueous phase, whereby to produce a gelled or thickened food product.

2. A method according to claim 1 wherein said aqueous phase has a pH
value of from 6.0 to 7.5.

3. A method according to claim 1 wherein said aqueous phase also con-tains a Plantago plant product selected from psyllium seed husk and gum.

4. A method according to claim 1 employing from 0.1 to 20% of the natur-al pectin source material by weight of the eventual product.

5. A method according to claim 1 wherein the foodstuff is animal protein material in an amount of 40 to 95% of the product, the pectin source material is comminuted citrus peel in an amount of 0.1 to 10% of the product and the product contains up to 5% non-toxic alkaline earth metal pound and O to 5% sequestrant and has a moisture content of 50 to 95%; the pec-tic substance of said peel forming with said moisture a gel bonding together said comminuted protein material into a coherent mass.

6. A method according to claim 1 of making a canned food product com-prising solid foodstuff including meats or meat by-products, an aqueous phase having a pH value in the range 5 to 8,5, and a quantity of a deesterified nat-ural pectin source containing pectic substance having a degree of esterifica-tion below 20% and containing at least one non-toxic di- or tri-valent metal ion, said pectic substance conferring on said aqueous phase when cold a gelled or thickened quality.

7. A method according to claim 5 wherein from 20 to 95% animal protein material is employed.

8. A method according to claim 1 wherein the foodstuff is vegetable pro-tein in an amount of 5 to 50% of the product, the pectin source material is comminuted citrus peel in an amount of 0.1 to 10% of the product and the pro-duct contains up to 5% non-toxic alkaline earth metal compound and 0 to 5%
sequestrant and has a moisture content of 50 to 95%; the pectic substance of said peel forming with said moisture a gel bonding together said vegetable protein into coherent formed pieces.

9. A method according to claim 1, wherein there are also added water soluble solutes and an antimycotic, the eventual food product being stabilised by the inclusion of sufficient of said water soluble solutes to reduce its water activity to between 0.65 and 0.85.

10. A method of making a food product comprising the steps of: (a) dissolving a deesterified natural pectin source material containing at least 5% pectic substance having a degree of esterification below 20% in an aqueous phase to confer on said aqueous phase when cold a gelled or thickened quality;
(b) preparing a mix including solid foodstuff and said aqueous phase; (c) causing said pectic substance to react with at least one non-toxic di-valent or tri-valent metal ion contained in said foodstuff, aqueous phase or pectin source material whereby to form a gel in said aqueous phase; and (d) cooling said mix to obtain a food product having a pH value in the range 5 to 8.5.

11. A method according to claim 10 including the step of causing said pectic substance to react with at least one alkaline earth metal ion contained in said foodstuff, aqueous phase or pectin source whereby to form the gel in said aqueous phase.

12. A method according to claim 11 including the step of dissolving a non-toxic di-valent or tri-valent metal compound and a sequestrant in said aqueous phase.

13. A method according to claim 10 including the steps of: heat treat-ing the mix and allowing the mix to cool and set said aqueous phase to a firm gel.

14. A method according to claim 13 wherein said heat treatment comprises sterilization of said mix within a sealed container.

15. A method according to claim 10 including the preliminary steps of comminuting a natural pectin source and treating said pectin source to reduce the degree of esterification thereof to below 10% to form said pectin source material.

16. A method according to claim 15 wherein said natural source comprises citrus peel and the preliminary steps include substantially removing the flave-do from said peel.

17. A method of making a canned meat product comprising the steps of removing the flavedo from pectin-containing citrus peel; comminuting said peel; reducing the esterification of said pectin in said comminuted peel to below 20%; preparing a mix containing meat or meat by-products, an aqueous phase, and the citrus peel; causing the pectate in said peel to react with a non-toxic di-valent or tri-valent metal ion contained in said meat or meat by-products, aqueous phase or citrus peel, filling said mix into containers and sealing them; retorting said filled and sealed containers to sterilize the contents thereof; and cooling said containers, thereby causing said aqueous phase to set to a gel having a pH value between 5 and 8.5.

18. A method according to claim 10 including the additional steps of shaping said mix containing said pectic substance; gelating said shaped mix while maintaining said shape; and introducing pieces of said shaped gelled mix into containers.

19. A method according to claim 18 wherein said pieces are filled into cans together with other foodstuff; said cans are sealed; said sealed cans are sterilized; and said sterilized cans are cooled, whereby the gelled con-dition of said pieces is restored without substantial impairment of their integrity.

20. A food product comprising solid foodstuff and an aqueous phase, the aqueous phase having a pH value in the range of 5 to 8.5 and being thickened or gelled by a deesterified natural pectin source material containing at least 5% pectic substance having a degree of esterification below 20% and containing at least one non-toxic di- or tri-valent metal ion, whenever made by the method claimed in claim 1 or 10, or by an obvious chemical equivalent thereof.