POWDER CHARACTERISTICS AND STORAGE STABILITY

The powder density of a typical standardized HM-pectin produced by alcohol precipitation is 0.70.

A typical mesh specification says: 90% through a 60 mesh (0.25 mm) sieve. The color of a commercial pectin may vary from light cream to light tan for an alcohol precipitated pectin or sometimes greenish yellow for an aluminum precipitated pectin. Apple pectins are generally darker than citrus pectins.

Commercial pectins will absorb water under most climatic conditions. Their equilibrium water content are:

9% in an atmosphere of 50% relative humidity.

12% in an atmosphere of 70% relative humidity (valid for a 150 grade HM-pectin blended from 70% pectin and 30% sucrose).

Pectins standardized with dextrose (9% water) have a higher moisture content than those standardized with sucrose (0% water) and have correspondingly higher equilibrium water contents in any atmosphere. Pectins are normally packed in vapor tight packaging labeled

STORE COOL AND DRY.

Stability

Powdered HM-pectins lose about 5% in jelly grade per year when stored at room temperature. Furthermore, HM-pectin is slowly de-esterified during storage, whereby e.g. rapid set pectin over a period of a year become a medium rapid set pectin. Degradation and de-esterification rates are more than doubles when the storage temperature is increased from 20 to

30(C. LM-pectins are more stable at storage than HM-pectins and degradation is normally not detectable over a period of a year at room temperature.

STANDARDIZATION

Pectins are standardized by the manufacturers to ensure that the users always get the same gel strength in their product and at the same point in the production process, provided the pectin is used under the same constant conditions.

High ester pectin

Commercial HM-pectins are characterized by, and standardized to, uniform "jelly grade" and gelling velocity. "Jelly grade" expresses the amount of sugar than can be gelled in a standard gel (standard composition and standard gel strength).

Various methods are used in measuring gel strength, the most common method being the SAG-method, where deformation by gravity of the demolded gel is measured. In other methods, breaking strength of the gel is determined. For specific applications the ratio between strength based on SAG-grade and strength based on breaking strength grade is of importance. In jellies, specifically confectionery jellies, a high breaking strength is required, whereas in jams the need for spreadability favors a pectin with a low breaking strength. International trade gives preference to the SAG-method developed by the US IFT in 1959 and published in Food Technology 13, 496 (1959).

The majority of HM-pectins are standardized to 150 grade USA-SAG, which means that 1 kg of standardized pectin will turn 150 kg of sugar into a standard gel (SS = 65.0%, pH = 2.2-2.4, gel strength = 23.5% SAG).

In other words:

1 kg 150 "jelly grade" pectin can set 230 kg standard jelly.

Gelling velocity of an HM-pectin jelly may be expressed as setting time or as setting temperature. None of these two characteristics are physical constants as they vary with

a) the composition of the jelly, i.e. pH, SS, pectin concentration, etc.

b) the cooling rate of the jelly.

The setting temperature of and HM-pectin jelly is defined as the temperature at which the first sign of gelation is observed. The setting time is defined as the time from the end point of the jelly preparation to the first sign of gelation.

The most commonly used method for determination of gelling velocity is the Joseph Baier method that enables gelling time and specifies the important variables as follows:

SS = 65%

pH = 2.2-2.4

Gel strength of test jelly = 23.5% SAG

Cooling rate = As obtained in a standard USA-SAG jelly glass in a 30C water bath.

The test jelly is in fact exactly the same as the one used for the USA-SAG grade determination.

Low ester pectin

LM-pectin may be graded by a method with some similarities to the USA-SAG method used for HM-pectin. The composition of the test jelly may for example be:

SS = 31.0%

pH = 3.0

Calcium concentration = 250 mg Ca/kg test jelly

or

25 mg Ca/g standardized 100 grade LM-pectin.

Jelly grade expresses the number of kg jelly of standard firmness (20.5% SAG) which can be produced from 1 kg LM-pectin. As application conditions for LM-pectin show rather wide variations, jelly grade methods are not always sufficiently relevant for the use of LM-pectin. Performance tests may be used as sole or additional test procedure.

QUALITY CONTROL

Purity determination

The "pure pectin" content is determined as percent anhydro-galacturonic acid by official method of Food Chemicals Codex (FCC), Third Edition, Washington, D.C., 1981 (incl. supplements), or as galacturonic acid by official method of FAO Food and Nutrition Paper (FNP), 52, 1992. The method involves washing of powdered pectin in a mixture of hydrochloric acid and 60% alcohol, which removes sugars and salts and converts the pectin to its acid form. If the galacturonic acid content as calculated on the acid/alcohol purified sample is low, it indicates the presence of non-uronic acid polysaccharide material in the pectin, or a pectin of low purity and often of low gelling power. Citrus pectins of high purity have a galacturonic acid content above 74%, which is the lower limit in USP XXII specifications for pectin.

Content of heavy metals in pectin is determined by official methods as published in FCC, FAO, FNP, EU Directive of 25th July, 1978 and USP XXII. A summary of various official purity specifications is shown in the table down below. Microbiological quality is determined by official methods.

Calcium reactivity

LM-pectins require a minimum calcium concentration in order to yield gels with desirable properties. At too high calcium levels, pregelation and tendency to syneresis occur. The "calcium working range" - or calcium reactivity - of a specific LM-pectin depends primarily on degree of esterification and degree of amidation., but is also influenced by degree of uniformity within and among molecules of the pectin lot.

Thus, calcium reactivity is not only controlled by proper processing conditions, but also through careful selection of suitable raw material. Calcium reactivity is evaluated in test jellies with different concentrations of calcium. The test jellies may be similar to those used for grade determination, except for calcium concentration.

FAO FOOD AND NUTRITION PAPER, 52, 1992

JECFA specifications for identity and purity of food additives, 1994; (anti-caking agents, buffering agents, salts, emulsifiers, enzymes, extraction solvents, flavoring agents and miscellaneous food additives).

FOOD CHEMICALS CODEX, Third Edition, Washington, D.C., 1981, (incl. Supplements).

EU Council Directive of July 25, 1978, laying down specific criteria of purity for emulsifiers, stabilizers, thickeners and gelling agents for use in foodstuffs (78/663/EEC) (plus Updates).

Purity specifications for pectin may be requested from any of our sales offices worldwide.

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