Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Flavor per se – or containing flavor or flavor improver of...
Reexamination Certificate
2000-07-19
2002-05-14
Wong, Leslie (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Flavor per se, or containing flavor or flavor improver of...
C426S573000, C426S650000, C549S435000
Reexamination Certificate
active
06387431
ABSTRACT:
The present invention relates to dicarboalkoxy dioxolanes and a citral release preparation containing these compounds.
Aldehydes represent an important class of flavor compounds that are ubiquitous in nature. This class of compounds is also of great value for providing consumer products with additional flavors or odors. However, the high reactivity of aldehydes such as citral can represent a major stability problem in the final product. The chemical properties of aldehydes and their reactivity towards nucleophiles are characterized by the terminal carbonyl group. Aldehydes are easily reduced to the corresponding alcohols, oxidized to carboxylic acids and undergo addition reactions such as also condensation. Due to the conjugated double bond unsaturated aldehydes have a strong tendency to polymerization. Such polymerisation can already take place during a longer storage period. Furthermore, unsaturated aldehydes can also undergo 1,4-addition reactions with sulfur leading to numerous impact flavor compounds (K.-H. Engel, R. Tressl, J. Agric. Food Chem. 1991, 39, 2249).
Citrus oils being a good source for a series of important aldehydes like aliphatic C
7
-C
12
aldehydes, citral and citronellal are used in a wide variety of applications. Citral, a mixture of geranial and neral, is one of the key impact components of citrus oils, and can be either isolated from natural raw materials such as lemon grass or can be synthesized e.g. starting from isoprenol. Besides natural citral, which is frequently preferred for its harmony, standardized synthetic citral is generally used in low cost bulk products. Synthetic citral is an important synthetic ingredient for flavors with a total consumption of about 100 tons in 1985 and an annual production of several thousand tons in the US [P. Z. Bedoukian, in Perfumery and Flavouring synthetics, Allured Publishing, Wheaton (1986), pp. 16-18].
Citral plays also a major role in the formulation of alcoholic and non-alcoholic beverages of the citrus type. These citrus beverages have typically a relatively low pH value in the range of 2-4. The stability of citral under these acidic conditions, e.g. aqueous lemon beverages, lemon oil emulsions etc., has been well investigated (H. Friedrich, B. A. Gubler, Lebensm.-Wiss. u. Technol. 1978, 11, 215-218; ibid. 1978, 11, 316-318). It has been shown that citral is degraded via a series of cyclization and oxidation reactions leading to a variety of compounds like p-cymene, p-cresol, carvone and p-methylacetophenone being responsible for the off-flavor in citrus beverages (K. Kimura, H. Nishimura, I. Iwata, J. Mizutani, J. Agric. Food Chem. 1983, 31, 801-804; P. Schieberle, W. Grosch, Z. Lebensm. Unters. Forsch. 1989, 189, 26; E. J. Freeburg, B. S., G. A. Reineccius, J. Scire, Perfumer & Flavorist 1994, 19, July/August, 23-32).
According to a current principal strategy aldehydes are stabilized in consumer products by admixing with a matrix that slows or prevents release of the aldehydes until the product is pyrolized, heated, mascicated or wetted. As an alternative, the aldehydes may be covalently bound to auxiliary components to form higher molecular weight molecules of low volatility. The aldehyde is then released upon pyrolysis, heating or solvolysis. Acetals have also been used as vehicles to covalently bind aldehyde flavorants. For example, U.S. Pat. No. 4,296,137 describes the use of 1-ethoxy-1-ethanol acetate as a flavor or fragrance enhancer of a wide variety of consumable materials. U.S. Pat. No. 4,280,011 describes the use of acetals as aldehyde generators in food applications. U.S. Pat. No. 3,625,709 discloses food flavoring and aroma enhancer compositions consisting of acetaldehyde combined with carbohydrates. These compositions release acetaldehyde when combined with hot or cold water. EP-A1-0 501 645 describes the preparation of tartrate acetals or ketals as flavor-releasing additives for smoking compositions which, under smoking conditions, release volatile aldehyde or ketone flavors into the smoke. U.S. Pat. No. 5,144,048 describes dicarboalkoxy dioxolane derivatives as precursors which release an odorant molecule. They are useful in tobacco, cooked food and chewing gum.
Since all these methods for stabilizing labile aldehydes are well known, it seemed obvious to test citral dimethyl acetal and citral propylene glycol acetal as possible citral precursors (A. Sharama, S. Nagarajan, K. N. Gurudutt,
J. Agric. Food Chem
. 1998, 46, 654-656). However, these compounds are rapidly hydrolized in aqueous solutions and in acidic aqueous alcoholic and non-alcoholic beverages. Due to their short half lives these compounds cannot be considered as useful for a consumer product and the instability of citral in acidic aqueous alcoholic and non-alcoholic beverages remains still unsolved.
This problem is solved by the present invention which provides dicarboalkoxy dioxolane derivatives of formula I:
wherein R
1
and R
2
are the same or different and stand for H, straight or branched alkyl, alkenyl, cycloalkyl, aryl, aralkyl.
It has been surprisingly found that the dicarboalkoxy dioxolanes of formula I, contrary to citral dimethyl acetal and citral propylene glyco acetal (A. Sharama, S. Nagarajan, K. N. Gurudutt,
J. Agric. Food Chem
. 1998, 46, 654-656), have much longer half lives in acidic aqueous alcoholic and non-alcoholic beverages. In contrast to citral dimethyl acetal and citral propylene glyco acetal the half lives of the dicarboalkoxy dioxolanes of formula I are within a useful range for a consumer product. Surprisingly, the dicarboalkoxy dioxolanes of formula I release citral (geranial and neral) over a prolonged time. It is further surprising that the release rate can be modulated by varying the ester groups R
1
and R
2
. Small groups R
1
and R
2
give raise to short half lives, whereas bulkier groups and longer alkyl chains give rise to dicarboalkoxy dioxolanes of formula I with long half lives. Hence, using citral release preparations with different release profiles can be designed. This is especially useful for acidic aqueous alcoholic and non-alcoholic beverages with varying shelf lives. E.g. a citral release preparation with a short half life is suitable for an instant beverage, whereas a citral release preparation with a long half life is more suitable for a ready to consume beverage with a certain shelf life.
The compounds of formula I are not limited to any particular stereoisomer and all possible stereoisomers are included within the scope of the invention.
The compounds of formula I are useful in consumer products, such as food products, especially in aqueous, alcoholic and non-alcoholic beverages of the citrus type. They stabilize the citral character of these products by releasing citral over a prolonged period. The release preparations are especially useful for instant beverages prepared by admixing dry beverage powders with water.
The citral release preparation may comprise a single dicarboalkoxy dioxolane derivative of formula I or a mixture of several dicarboalkoxy dioxolane derivatives of formula I. The preparations of the invention may also include (additional) flavors. The dry preparations are stable. After contact with water the flavors are released from preparation immediately, whereas the compounds of general formula I release citral slowly. Due to their long lasting citral taste, the resulting beverages are preferred to beverages without the citral release preparation.
The citral release preparations of the present invention are used in consumer products to provide the characteristic impression of citral over a prolonged period of time. The citral release preparation can be used in combination with citral, they can partially substitute citral usually present in lemon/lime or other flavorings and they can completely replace citral in a flavoring. Preferably the release preparations are used in combination with citral.
The release preparations of the present invention may be powders and may be prepared by methods known to the skilled in the art. The release preparatio
Givaudan SA
Wong Leslie
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