Specialized pectin blends selected for reduced sugar foods; benefits include whiter color, more resilient gel, and clearer solutions.
For example, in low-fat dairy products that are increasing in popularity due to their "healthy" image, a high-methoxyl pectin (HM) can be used as a stabilizer during the heat treatment of yogurt. In the preparation of gelled neutral products such as flan and dairy desserts, a low-methoxyl pectin (LM) is recommended.
Pectin is a natural carbohydrate present in combination with cellulose in plant cell walls. Although all plants contain pectin in different amounts, the most widely used source of pectin is fruits (e.g., dry apples and citrus peel). In unripe fruit, pectin is present as protopectin, which is insoluble in water. During ripening, an enzymatic action transforms the protopectin into water-soluble pectin. This pectin can be transformed into de-esterified pectic acid. The degree of esterification (DE, or sometimes DM for degree of methoxylation) plays an important role in pectin's functionality and divides pectins into HM and LM groups having very different characteristics.
Pectin production involves four principal steps: 1) extraction from plant material, 2) purification of the extracts via several filtration steps, 3) precipitation of pure pectin from the extracts, and 4) standardization. Pectin with a DE higher than 50% (more methoxyl groups than free acid groups) are classified as HM, and those with a DE of less than 50% are called LM. HM vs LM application A minimum amount of heat (in the range of 180-212 F) will make HM pectin functional. In addition, a TSS level of approximately 65 is required for the formation of limited crystallization resulting in gel structure. And, pH (ranging from 2.9-3.5) is the third parameter influencing gel structure. Gels obtained from HM pectins are not thermo-reversible.
An application suggested for HM pectin would be beverage concentrates, where the pectin is used to form a gel that breaks down on the addition of juice and yields a pulp-like texture.
De-methoxylation by acid hydrolysis on either the raw material or on the pectin extract is used to produce low methoxyl pectin. Two types of LM pectins have been developed: conventional LM pectin and amidated LM pectin. Conventional LM pectins require the addition of calcium salts in order to gel, but are more flexible than HM pectins with respect to the amount of solids needed for gel formation. TSS can range from 30-50% and pH should be 3.0-3.3.
Amidated LM pectin does not require addition of calcium salts for gelling. These gels have better heat-reversible properties than conventional LM pectins, exhibit less syneresis, and are more transparent. A major supplier also has developed a pectin blend--consisting of amidated LM pectin, a buffer, and citric acid--for use in instant desserts. The addition of hot water results in a soft gel with a consistency of mousse or yogurt.
The application of pectin in the manufacturing of jellies, jams, and marmalades is one of the oldest and most important of the fruit processing industry. Whereas the fruit gives flavor and identity to the product and the sugar adds sweetness, pectin is the gelling agent. In jams with a TSS higher than 60%, perfect gellation is obtained by using HM pectin. However, LM pectins have been used recently to yield a creamier and more spreadable consistency. Below 60%, LM pectins must be selected for effective gelling.
Other food applications for pectin could include sugar-free gelatin desserts (e.g., cherry-flavored); low-calorie, sugar-free, no-juice jellies (e.g., strawberry); low-calorie with added fruit juice, and sugar-free jellies (e.g., grape or apple).
More information on CESAPECTIN HM, LM, and Blend Pectins is available from TIC Gums, Inc., 4609 Richlynn Dr., Belcamp, MD 21017.
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|Author:||Duxbury, Dean D.|
|Date:||Dec 1, 1992|
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