Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2000-10-10
2004-03-02
Wilson, James O. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C424S489000
Reexamination Certificate
active
06699977
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to low methoxyl pectins that display pseudoplasticity and no phase separation in aqueous solution comprising at least one polyvalent cation, and processes for producing the same. In particular, the present invention is directed to low methoxyl pectins prepared from non-calcium sensitive pectins. The present invention is also directed to processes for suspending particulates using low methoxyl pectins prepared from pectins which are not sensitive to polyvalent cations such as calcium, and in particular using low methoxyl pectins prepared from non-calcium sensitive pectins (NCSP). Furthermore, the present invention relates to stabilizing particles in aqueous systems containing low methoxyl pectins prepared from non-calcium sensitive pectins.
2. Background of the Invention and Related Art
The problem encountered with drinks containing insoluble components, such as pulps, clouds, insoluble particles, essential oils, and the like, is the tendency of the insoluble components to separate, e.g., via sedimentation or creaming.
In order to maintain insoluble components in suspension, xanthan has been added to fruity drinks to raise the viscosity or alter the rheology of the drink. Xanthan, when added to aqueous solutions even at low concentrations, also exhibits very strong pseudoplasticity and pseudoplasticity at low concentration without any evidence of thixotropy. However, xanthan results in negative organoleptic perception (undesirable mouth-feel) in beverages. Thus, there is a need to provide a suspension aid that has the desired particle suspension properties of xanthan without the undesired mouth-feel.
Alginates and pectins have also been used in beverages in an attempt to suspend insoluble particles. Alginates and pectins, however, tend to undergo syneresis or phase separation during long term storage. Attempts have been made to use pectins as suspension aids with reduced syneresis properties. Pectins are complex polysaccharides having exposed reactive carboxylic acid moieties. More specifically, pectins are composed primarily of D-galacturonic acid, interrupted with sugars such as L-rhamnose. The D-galacturonic acid subunits have reactive sites. In the presence of a polyvalent cation, such as calcium (Ca
2++
), the acid moieties or reactive sites of dissolved pectin form a bridge across the calcium with the acid moieties from other nearby pectin molecules, forming a gelatinous mass.
Pectin is available as either a low methoxyl pectin (LMP) or high methoxyl pectin (HMP). Low methoxyl pectin has a degree of esterification (DE) of less than about 50% and is highly reactive with cations. High methoxyl pectin has a DE of greater than about 50% and is less reactive with polyvalent cations such as calcium.
The term “degree of esterification” is intended to mean the extent to which free carboxylic acid groups contained in the polygalacturonic acid chain of the pectin have been esterified (e.g., by methylation) or in other ways rendered non-acidic (e.g., by amidation).
The structure of the pectin, in particular the DE, dictates many of the resultant physical and/or chemical properties of the pectin. Pectin gelation also depends on the soluble-solids content, the pH and calcium ion concentration. With respect to the latter, it is believed that the calcium ions form complexes with free carboxyl groups, particularly those on LMP.
Pectin, as first extracted, has a relatively high degree of esterification of about 70-75%. Such pectin is ideal for use in jam and jellies. However, other uses require the preparation of pectins with different setting characteristics. This can be accomplished by modifying pectin to reduce the degree of esterification. One common process for achieving this is an acid hydrolysis. Alternative processes are directed to the use of alkali at low temperatures, ammonia, or purified pectin esterase.
During deesterification, the ester groups on the pectin can be removed in a random or blockwise manner. When the ester groups are removed from any galacturonic acid residues chemically or when using very specific enzymes, deesterification can occur in a “random manner.” When the ester groups are removed either at non-reducing ends or next to free carboxyl groups by a single-chain mechanism, they are referred to as being deesterified in a “blockwise manner,” as blocks of unesterified galacturonic acid units are created. The unesterified galacturonic acid units formed by blockwise deesterification are highly reactive to polyvalent cations. Pectins having such blocks are said to be “calcium sensitive.”
Pectins that have been reduced to low methoxyl pectins can gel in the presence of polyvalent cations. Calcium is the most common source of polyvalent cations for food gel applications. Gelation is due to the formations of intermolecular junction zones between homogalacturonic acid units. Because of the electrostatic nature of the bonds, pectins gels are very sensitive to conditions which can modify the environment of the carboxyl groups through which the calcium ion is linked to a neighboring pectin molecule. The gel forming ability of pectin increases with decreasing DE, and low or high methoxyl pectins with blockwise distribution of free carboxyl groups are very sensitive to low calcium levels. As the number and size of blocks along the pectin backbone increase, the sensitivity to calcium increases. However, a typical problem associated with the increasing sensitivity of a pectin to calcium is an increased tendency for the pectin to pre-gel and to display syneresis.
Amidation also increases the gelling ability of low methoxyl pectins. Amidated pectins require less calcium to gel and are less prone to precipitation at elevated calcium levels. Amide groups along the pectin backbone associate through hydrogen bonding allowing gelation at lower calcium levels.
Attempts have been made in the industry to use pectin as a suspending aid. For example, U.S. Pat. No. 5,866,190 issued to Barey discloses compositions for stabilizing a non-milk drink containing insoluble components comprising a pectin and alginate. The pectin of Barey can be amidated or non-amidated HMPs and LMPs. These compositions, however, display high levels of syneresis. It is also essential that the pectin/alginate mixture be dissolved in aqueous medium in the absence of free calcium ions or that a calcium complexing agent be used. The complexing agent is added either to the pectin/alginate solution or to the fruit juice.
EP 0 664 300 A1, and U.S. application Ser. No. 08/161,635 now U.S. Pat. No. 6,143,346 and Ser. No. 08/890,983, now U.S. Pat. No. 6,207,194to Glahn disclose the use of pectin as a suspension aid in foodstuffs, personal hygienic devices, and in cosmetics. The pectin of Glahn, however, displays an increased tendency to form gels which show high levels of syneresis.
The pectin of Glahn is HMP containing two fractions, a calcium sensitive pectin (CSP) and a non-calcium sensitive pectin (NSCP). “Non-calcium sensitive pectin” fraction refers to a fraction having a lower degree of calcium sensitivity. “Calcium sensitive pectin” fraction refers to a fraction having a higher degree of calcium sensitivity. “Calcium sensitivity” is intended to mean the ability of pectin to become viscous in solution by the addition of calcium.
Typically, commercial low methoxyl conventional (LMC) and low methoxyl amidated pectins are prepared from the unfractionated pectin (containing CSP and NCSP as disclosed in Glahn). Random deesterification by chemical methods and/or enzymatic processes is typically used to prepare low methoxyl pectin from an unfractionated pectin precursor. The resulting pectin is a mixture of low DE CSP with carboxyl blocks of increased size and number with a low DE NCSP fraction with completely random carboxyl distribution. These pectins with larger and more numerous carboxyl blocks are more sensitive to calcium, and thus display an increased tendency to form gels which show high levels of syneresis.
In view of
Chambliss Kenneth LeRoy
Forman Susan C.
Gerrish Timothy C.
CP Kelco ApS
Greenblum & Bernstein P.L.C.
Krishnan Ganapathy
Wilson James O.
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