CH631056A5 - Process for increasing the fresh natural flavour of a foodstuff and linear acetal for implementing the process - Google Patents

Description

The present invention relates to a new process for increasing the fresh natural flavor of a food product by incorporating an aldehyde naturally present in this product.

The invention also relates to linear acetals for implementing the method.

It is well known that both acetaldehyde and propion-aldehyde are found in a wide variety of fresh and prepared food products, such as fruits, meat, dairy products, baked goods and vegetables. It has been found that aldehyde is of particular importance in contributing to the flavoring effect and the freshness effect of certain food products, in particular the fruits of the lemon family and of the type of red berries. As such, it is essential in the preparation of artificial flavorings in which a freshness effect is sought. The same can be said of propionaldehyde which also contributes to the flavoring of a wide range of fruits and other foods.

Other aliphatic aldehydes, such as butyraldehyde, octylaldehyde and the like whose number of carbon atoms varies between C4 and C12, are known to impart impact and some special flavoring effects in a wide variety of aromatics corresponding to their natural presence in a wide variety of food products. For example, we find butyraldehyde in apples, strawberries, milk, fish, beef, pork, beer, bananas, blackcurrants, grapes, peaches, onions, potatoes, ginger, bread and Roquefort; 2-methyl-propanol is found in potatoes, tomatoes, bread, blue cheese, milk, cocoa, eggs, fish, beef, pork and cherries; 2-methylbutanal is found in cocoa, egg, fish, beef, beer, currant and olive; 3-methylbutar-aldehyde is found in cocoa, fish, chicken, beer, peanuts, currants, olives, peaches and mushrooms; we find valér-aldehyde in milk, tea, fish, chicken, beef, pork, beer, cranberry, currant, grapes, olive, mushroom, onion and potato. 2-ethoxypropanal is found in rum, as well as 3-ethoxypropanal; 3-methylpropanal is found in beer; 2-methylpentanal in onion; 2-ethyl-butanal in lemon and bread; hexanal in banana, lemon, soy, milk, fish, chicken, beef, lamb, tea, currant, grape, olive, melon, peach, cucumber , the

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mushroom, onion, potato, tobacco; we find heptaldehyde in lemon, redcurrant, cranberry, grapes, olive, peach and bread; octaldehyde is found in bread, carrot, olive and lemon; nonylaldehyde in bananas, lemon,

cranberry, milk, fish, beef, beer, tea, chicken, currant, melon, olive, carrot, ginger and bread; the decanal in bread, ginger, milk, fish, cocoa, beer, cucumber, grapes and lemon; undecylaldehyde in lemon, milk, fish, beef and cucumber while dodecanal is found in milk, fish, beef, lemon, grapes and cucumber; cis-6-nonenal in melon and cucumber, and phenylacetaldehyde in peach, beans, mushrooms, mint and blue cheese.

Considerable efforts have been made over the past two decades, as demonstrated by the abundant literature on the subject, to find a stable or fixed form of this aldehyde, which would only be released under the desired conditions of application and not previously. The main reason for this difficulty in fixing acetaldehyde lies in its physical characteristics, since it is a gas at room temperature (21 ° C) - that is to say under the conditions ambient normal -, that it is miscible with water and that it has a high degree of reactivity and chemical instability. This chemical instability is illustrated by its tendency to polymerize or to form paraldehyde and metaldehyde, to oxidize to acetic acid or to combine chemically with itself or with other materials in the presence of an acid or d 'a base.

To achieve the fixation of acetaldehyde, the researchers attempted to imprison it in a crystalline defect or in complexes with clathrate inclusion of a wide variety of types, including those based on oligosaccharides or monosaccharides. The inclusion complexes release acetaldehyde under conditions of use such as when a powder for dry drinks is dissolved in water.

The disadvantage of this process is that in general only a small amount of this aldehyde is fixed in stable form by these methods, which requires a large proportion of inclusion matrix relative to the aldehyde, which makes the use of aldehyde in this very expensive form. For example, US Patent No. 3,314,803 discloses a method for encapsulating acetaldehyde in a mannitol matrix. An initial acetaldehyde entrapment of 2 to 10% is carried out by drying, by spraying with a mannitol / acetaldehyde mixture. When exposed to ambient conditions, in the open atmosphere, acetaldehyde is however quickly lost in the atmosphere and in a few days its content is reduced to a maximum proportion, stable in the long term, from 1 to 2.5% . This loss of acetaldehyde from the matrix is even observed when the product encapsulated is incorporated into a food product such as a dry powder for beverage contained in a package, particularly in the presence of small amounts of water or water vapor, may be present either in the basic food product itself, or involved in normal packaging operations.

Other examples of inclusion matrices of Polysaccharides, described in the patents, are for example a carbohydrate complex as described in US Patent No. 3,625,709, the use of an arabinogalactan described in US Patent No. 3264114 and the use of lactose described in US Pat. No. 3,736,149. All of these methods have the disadvantage of a low degree of acetaldehyde fixation. In addition, they exhibit instability in the presence of small amounts of water or water vapor which may be encountered during storage in a non-hermetically sealed package, sufficiently permeable to allow atmospheric moisture to penetrate, or the contact with water or water vapor during normal treatment or conditioning operations.

In US Patent No. 3,767,430 describes a method for fixing acetaldehyde in a sucrose crystal matrix, but the amount of acetaldehyde is less than 0.01% and generally of the order of 0.01 to 0, 05%.

A second method for fixing acetaldehyde consists in preparing chemical derivatives which must satisfy several often contradictory requirements, including that of chemical inertness and of stability under the usual conditions of storage, the rapid release of the aldehyde. to the mixture of the preparation of the food product for the purpose of preservation and the property of not disturbing the aroma or the taste of the desired flavoring. To satisfy this latter need, the derivative and its conversion products, other than the desired aldehyde, must be relatively odorless and tasteless.

Numerous attempts to obtain suitable chemical derivatives in order to release acetaldehyde have been demonstrated in the literature. A wide variety of aldehyde derivatives have been proposed to give rise to acetaldehyde, namely carbamates, carbonates, ureides, ethylidene compounds (US Patent No. 2,305,620) and certain acetals (US Patent No. 3,857,964 ). All these derivatives have at least one of the following drawbacks: production of secondary tastes, toxicity, or stability too high to release the aldehyde in the desired food product at an appropriate rate.

The application of the well known acetals of acetaldehyde, propionaldehyde and other aliphatic aldehydes - up to dodecylaldehyde - obtained from monoalcohols such as dimethyl, diethyl, and dihexyl acetals is recognized to be impossible because of the taste of the acetal itself, which is usually unacceptably different from that of the starting aldehyde and therefore with the desired aromatization balance, in particular in the case of the aldehyde acetals in Cj- Cg. In addition, the use of alcohols to prepare such an acetal is limited to those having 1 to 5 carbon atoms, because those in C6 and more, going up to approximately Ci2, bring their own flavor and thus distort the aromatization wanted.

The present invention makes it possible to obtain aldehyde acetals derived from high molecular weight polyols or monoalcohols fulfilling the most important requirements for the stability and fixation of aldehydes in flavorings and flavored basic food products, at the same time ensuring an effect of rapid release under conditions of use and consumption. These acetals do not interfere with the desired flavoring, are stable with respect to humidity, heat and oxidation under normal conditions of storage, are capable of being incorporated into a flavoring product dry and remain stable, and they provide a higher percentage of fixed and stable acetaldehydes in a dry flavor or flavor base than has been found possible so far.

The acetals according to the invention consist of structures of type I and II below, in which the acetal is linear, that is to say in which the oxygen is not both in the same cycle, as c 'is the case in acetals of the 1,3-dioxolane or metadioxane type. In structures I and II, R and R2 may be any combination of hydrogen atoms, alkyl, alkoxy, acyl, carboxy groups or alternatively alkyl groups substituted in turn by ethers, carboxy or acyls, and R and R2 can be combined by forming a cyclic structure of the acetal type, R, must be the same as R and R2 or represent

(CH-0-C-0R4)

and n is an integer number chosen from 0 to 5, it being understood that when n = 0, R cannot represent hydrogen. R3 represents a hydrocarbon residue of Cx at approximately Cn, corresponding to the desired aldehyde minus one carbon atom, and Rs in structure II corresponds to the desired aldehyde minus two carbons. R4 is a hydrocarbon residue of up to 7 carbon atoms, corresponding to alcohols that do not have a marked taste, such as benzyl, methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, prenyl , butenyl and preferably methyl or Tethyl. R4 can also represent an acyl group derived from an acid which, released on hydrolysis, does not deform the desired flavor such as the mono-methyl ester of lactic acid or of malic acid.

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4

R

I

1 | 2? 3 (CH — OC-O-R.)

I

R. C — R „

R

R C R

i

X |

R

II

The acetals in accordance with structures I and II above are illustrated by way of nonlimiting example by the types shown in FIGS. 1 and 2, in which (ald) represents an alkyl residue of 1 to 12 carbons and (aie) represents an alkyl residue of 1 to 5 carbons. The acetals according to the invention can be synthesized in the presence of an acid catalyst by reaction of the appropriate vinyl ether with the desired polyol, such as for example the reaction of propylene glycol (III) with ethyl propenyl ether (IV). which gives the compound (V).

-OH

C OH

/ m

The polyols, or high molecular weight monoalcohols, found usable are propylene glycol, glycerol, lemannitol, sorbitol, neopentylglycol, pentaerythritol, monoethyl ether of diethylene glycol, hexamethylene glycol, diethyl malate or any other relatively soft monoalcohol or polyol capable of forming a linear acetal by reaction with vinyl ethers.

The structures shown in fig. 3 are additional but non-limiting types of mono or polyols which can be used. The molecular weight of the monoalcohol or of the polyol is limited in practice depending on the weight of the acetal derivative relative to the amount of acetaldehyde which must be released. The symbols (ald) and (aie) have the meanings previously mentioned for figs. 1 and 2. For the higher aldehydes (C3 to C12), the hydroxylated compound VI is reacted with the corresponding higher vinyl alkyl ether VII, as shown below, R, Rl5 R2, R4 and R5 having the above meanings:

R

-OH

VI

R

4 VII.

R

-0-

• R.

R „

VIII

In the case where a polyhydroxy compound carries vicinal OH groups, it is possible to form a 1,3-dioxolane structure of type IX and in a similar manner if the OH groups are on alternating carbon atoms, a structure 1, 3-dioxane X can result. This tendency to form cyclic acetals becomes evident if one attempts to form linear vicinal acetals such as 1,2,3-tris [(ethethoxy) ethoxy] propane.

X

Cyclic acetals such as those having the above-mentioned dioxolane or metadioxane structures are too stable at the pH of lemon drinks, such as orange juice or grapefruit juice (this pH being about 1.8 to 3.5) , to hydrolyze to an appreciable degree to give acetaldehyde. For example, the compounds of the 1,3-ethylidene glycerol and 1,2-ethylidene glycerol type do not hydrolyze in lemon drinks to an appreciable degree at room temperature.

In a literature search for processes for the synthesis of 1,2,3-tris - [(l'-ethoxy) ethoxy] propane, it has been found that this compound has never been prepared well. that we have tried several times to do so. Russian researchers have published several articles on the reaction of ethyl vinyl ether with glycerol and the reaction of trivinyl ether of glycerol with alcohols:

a) M.F. Shostakovsky et al., “Bull. Acad. Sci. ", USSR," Div. .40 Chem. Sci. ”, 137-40 (1954)

b) M.F. Shostakovsky et al., ibid. 583-7 (1954)

c) M.F. Shostakovsky et al., ibid. 313-6 (1955)

d) M.F. Shostakovsky et al, ibid. 317-20 (1955)

Thus, l, 2,3-tris - [(l'-ethoxy) ethoxy] propane XI therefore appears well 45 in the literature to have been sought but it seems that one has failed in its synthesis. It is presented as unstable, decomposing giving dioxolane XII when the ethyl vinyl ether is reacted with glycerol in acid catalysis or when the trivinyl ether of glycerol XIII is reacted with ethanol.

50

(Formulas at the top of the next page)

In the two syntheses using the trivinyl ether of glycerol and the ethyl vinyl ether of glycerol, the reaction mixtures are allowed to reach their natural temperature by combining all the reagents. The exothermic reaction raises the temperature in each case to 75-95 ° C. It has been made the surprising discovery that when the reaction temperature is kept below about 120 ° C and the vinyl ether reagent is always maintained at approximately 60 molecular equivalent relative to the moles of the reactive alcohol, by concurrent addition of alcohol and vinyl ether, the formation of the cyclic products is suppressed. Thus by simultaneous addition drop by drop of 4 mol of ethyl vinyl ether and 1 mol of glycerol in a flask containing hydrochloric acid as catalyst 65 and of a solubilizing mixture constituted by the dimethyl ether of diethylene glycol and chloride trimethylhexadecylammonium, we are able to form the compound I which had not been synthesized until now.

631056

Ref.a, c

Ref. d

C x

XII

AT

Ref. d

0 ^

-0 + EtOH

-0 XIII

It has also been discovered that the analogous reaction can be successfully carried out on other polyhydroxy compounds such as propylene glycol, mannitol, sorbitol and the like, to obtain the corresponding multilinear acetals. Since materials such as mannitol and sorbitol are not soluble in ethyl vinyl ether, the reaction can be facilitated by the use of a non-reactive cosolvent for the polyhydroxylated compound, such as dimethylform amide, hexamethylphosphoric triamide. , dimethyl sulfoxide or N-methyl-2-pyrrolidone. Multilinear acetals derived from polyols constitute, as far as is known, a new class of compounds which it would not have been possible to reach by known techniques of synthesis. The synthetic method described above was used on glycerol to obtain trislinear acetal I with a yield of 31%, in mixture with acetal II, obtained with a yield of 36.4%, or on propylene glycol to obtain dilinear acetal III with a yield of 67% and on mannitol in N-methyl-2-pyrrolidone as solvent to obtain acetal IV with a yield of approximately 70%.

XIV

turned yellow. The mixture is then kept under reflux while stirring for an additional 1 hour at 40 ° C. while heating gently. After standing at room temperature for 14 h, the reaction mixture is quenched with 10 g of sodium carbonate with stirring. After having distilled it off to a pot temperature of 110 ° C and a head temperature of 56 ° C under 760 mm of mercury, the products are immediately distilled under the conditions indicated below to obtain 588 g of a yellow oil containing 51.4% of 1,2,3-tris - [(r-ethoxy) ethoxy] -propane (yield 31%) and 37.3% of 4- (l -ethoxy) ethoxymethyl- 2-methyl-1,3-dioxolane (36.4% yield):

Temp. pot 60-212 ° C

Temp. head 40-144 ° C

Empty

10-0.1 mmHg

40

The distillate is rectified on a Goodloe column of 25 mm x 30 cm, with 7 trays as follows:

(Table at the top of the next page)

The purity of the acetals is determined by gas chromatography. For the 1,2,3-tris - [(r-ethoxy) ethoxy] propane, a 180 cm x 6 mm stainless steel column is used with a filling in Chromasorb W washed with acid at 20% SE30, programmed from 135 to 220 ° C at 4 ° / min, helium flow rate 60 ml / min and for 4- (l'-ethoxy) ethoxymethyl-2-methyl-1,3-dioxo! ane, a column of 20 m of Carbowax at 20%, the other parameters remaining the same.

Spectrum and physical properties A) 1,2,3-tris [(l'-ethoxy) ethoxy] propane

25

d— = 0.9561 25

nfj = 1.4222

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Example 1:

4- (l'-ethoxy) ethoxymethyl-2-methyl-1,3-dioxolane and 1,2,3 - [(1'-ethoxy] propane

In a 2000 ml flask equipped with a mechanical stirrer,

5 ml of 36% hydrochloric acid and 1.6 ml of 50% trimethylhexadecylammonium chloride are introduced into a heating jacket, a thermometer, a condenser and two addition funnels. isopropanol. Then added simultaneously and drop by drop to 65 drop 294.4 g of glycerol (3.16 mol) and 921.6 g of ethyl vinyl ether (12.8 mol) at a proportional rate, over a period of 1 h, between 23 and 39 ° C. The reaction mixture is homogeneous at this point and is

Mp = 117 ° C at 1.0 mmHg; 102 ° C at 0.11 mmHg NMR spectrum

Methyl protons [18 H], uneven quartet having its center of gravity at ~ 1.158; monoalkoxy protons [11 H], broad multiplet having its center of gravity at ~ 3.48 S; protons dialkoxymethine [3H], large multiplet having its center of gravity at ~ 4.67 S.

IR spectrum (CC14 solution)

Strong band of C — O — C ether at 1054 cm-1.1080 cm-1.1095 cm-1, 1105 cm "1 and 1133 cm" 1 (band of maximum intensity in the spectrum).

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Duration (h)

Temperature

Temperature

Vacuum (mm Hg)

Weight (g)

Acetal

pot rc)

head (C)

Linear fraction (%)

Dioxolane

Comments

0

24

23

1.8

R.R. 2: 1

2.75

124

48

0.10

1

52.2

96.3

3.25

129

48

0.08

2

50.6

99.7

3.83

155

51

0.09

3

50.4

99.9

R.R.20: 3

4.61

163

49.5

0.08

4

40.7

96.6

5.36

167

58

0.08

5

30.5

97.5

5.72

170

78

0.08

6

13.7

46.7

6.14

171

92

0.13

7

13.3

14.6

6.61

178

98

0.10

8

17.8

64.6

7.76

184

117

1.0

9

57.9

98.1

8.08

207

102

0.11

10

38.3

99.5

R.R.10: 20

8.24

210

105

0.13

11

48.2

99.8

8.5

210

108

0.11

12

56.2

99.9

8.67

211

102

0.11

13

58.1

99.9

B) 4- (1 '-ethoxy) ethoxymethyl-2-methyl-1,3-dioxolane 25

d— = 1.0073 = 1.4243

25 D

PE = 51C to 0.09 mmHg

NMR spectrum

Multiplet of acute peaks (~ 6) having its center of gravity at ~ 1.2 S, 3-methyl groups, 9 protons; large multiplet ranging from 3.1 S to 4.3 <), alkoxy protons, 7 protons; 4.66 S-centered quartet, linear acetal-methine, 1 proton; 5.01 S-centered quartet, dioxolane acetal-methine, 1 proton.

IR spectrum (Solution in CC14)

Strong ether bands C — O - Center 980 and 1200cm -1.

Example 2:

1,2-di- [(l'-ethoxy) ethoxy] propane

8 drops of 36.5% hydrochloric acid are introduced into a 250 ml flask equipped with a condenser, a static nitrogen introduction head, a mechanical stirrer and two addition funnels. , 7 ml of bis- (2-methoxethyl) ether and a drop of 50% trimethylhexadecylammonium chloride in isopropanol. 43.3 g of ethyl vinyl ether and 15.2 g of propylene glycol at 40 ° C over 23 min are then added dropwise through separate addition funnels, but simultaneously at a proportional speed. The reflux is continued for another 2 h at 40 ° C., the mixture is cooled and 0.4 g of solid sodium hydroxide is added. The product is distilled directly under vacuum in a 42 cm x 10 mm tube with the following parameters:

30

Duration (h)

Storage temperature (C)

Head temperature (C)

Vacuum (mmHg)

Fraction

Weight (g)

Product (%)

Comments

0

22

20

5

Hunted heads

1.55

82

28

0.03

1.62

85

28

0.12

1

3.1

0.2

3 ml collected

1.98

92

46

0.09

2

0.54

26

2.20

94

49

0.08

3

6.1

97

Interrupted and restarted

2.53

67

20

0.04

3.21

94

44

0.02

4

7.3

99.7

3.34

95

43

0.06

5

5.5

99.9

4.79

98

46

0.04

6

4.3

98

4.92

112

47

0.04

7

4.4

99

5.05

126

43

0.08

8

1.3

99

5.34

142

45

0.07

9

1.14

98

5.61

165

50

0.1

10

0.42

93

5.76

165

55

0.09

11

0.34

75

Yield: 29.5 g, 67.1 M.

Spectrum and physical properties 25

d— = 0.9153 n “= l, 4112 25

PE = 47: C at 0.04 mmHg NMR spectrum

Multiplet with a center of gravity at 1.18 S, 15 protons, methyl groups; large multiplet with center of gravity at 3.57 S, 7 protons,

hydrogens adjacent to oxygen; large multiplet centered at ~ 4.71 S, acetalmethine protons.

60 IR spectrum

Strong absorption of C — O — C ether between 1020 cm-1 and 1200 cm-1 with maximums of 1061 cm "1.1087 cm-1, 1104 cm-1 and 1140 cm-1.

65 Example 3:

l, 2- (l'-ethoxy) propoxy] propane

In a 50 ml flask equipped with an addition funnel, a

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magnetic stirrer, thermometer and static nitrogen introduction head, 15 g of propenyl ether, 5.1 g of propylene glycol, 6.2 g of bis- (2-methoxyethyl) ether are introduced and a drop of 50% trimethylhexadecylammonium chloride in isopropanol. 5

3 drops of concentrated hydrochloric acid are added and the mixture is stirred at 41 to 43 ° C for 3 h, cooled and left to stand at room temperature overnight. After heating at 40 ° C for a further 3 h, the mixture is quenched with 4.5 g of KOH. The product is distilled under vacuum on a small column with the following parameters:

Duration (h)

QC deposition temperature

Head temperature

CQ

Vacuum (mmHg)

Fraction

Weight (g)

Product (%)

0

23

22

0.48

49

25

0.4

2.35

83

62

0.08

1

0.42

52.5

2.42

84

63

0.08

2

1.54

95.1

2.52

89

65

0.09

3

2.36

98.9

2.69

114

64

0.05

4

1.41

98.6

Fraction 3 has the following properties: 20

NMR spectrum

Multiplet ranging from 0.7 S to 1.9 S for methyl hydrogens and ethyl hydrogens CH2-19 protons; complex multiplet ranging from 3.1 S to 4 8 having a center of gravity at ~ 3.5 8 for protons has up to only one oxygen, 4 protons; 25

multiplet (broad quintet) ranging from 4.2 8 to 4.6 8 for the hydrogens acetalmethine, 2 protons.

IR spectrum (beef foot oil)

Strong ether bands C — O — Center 950 cm-1 and 1200 cm-1 with 30 maximums at 973, 1034, 1065 and 1132 cm-1.

Example 4:

1,2,3,4,5,6-hexa- [(l'-ethoxy) ethoxy] hexane

In a 250 ml flask fitted with an introduction head 35

of static nitrogen and of a magnetic stirrer, 18.6 g of mannitol, 100 ml of N-methylpyrrolidone and 64.8 g of vinyl ether are introduced. 10 drops of concentrated HCl are then added and the mixture is stirred at 22-28 ° C for 4.5 h and allowed to stand overnight. The following day, an infrared spectrum of a suitably treated sample reveals the practical absence of any absorption band of hydroxyl and C — O — C ether. The reaction mixture is poured with stirring into 750 ml of water containing an excess of NaOH and it is extracted twice with 150 ml portions of hexane. Each extract is washed with two 750 ml portions of water. The combined organic phases are dried over a mixture of sodium carbonate and solid sodium sulphate and evaporated in vacuo to about 10 mmHg, which gives 59 g of crude oil. Distillation is carried out on a short-path microcolumn under the following conditions:

Load: 19 g of crude + 0.2 g of Na2C03

Time

(h)

Pot temperature

CQ

Head temperature

CQ

Vacuum (mmHg)

Fraction

Weight (g)

0

55

22

0.5

0.35

185

170

0.5

1

-

1.35

182

175

0.6

2

0.2

1.62

184

176

0.6

3

0.4

1.65

185

176

0.6

4

2.3

1.70

186

176

0.6

5

0.7

1.77

187

178

0.6

6

4.4

1.80

180

174

0.6

7

1.5

1.83

182

174

0.5

8

0.8

1.89

186

176

0.5

9

3.1

1.75

184

175

0.5

10

1.9

IR spectrum (solution in CC14)

Broad band weak at 3500 cm-1 indicating some free hydroxyls; strong bands of C — O — C ether extending between 990 cm -1 and 1200 cm -1 with maximums at 1044.1082 and 1136 cm-1.

NMR spectrum (CC14 solution, TMS reference)

Unsymmetrical quartet ranging from 1.0 S to 1.48 with center of gravity at ~ 1.25 8, methyl protons, 34.5 protons (theory 36); large multiplet ranging from 3.2 8 to 4.0 8 having a center of gravity at ~ 3.6 8, hydrogens and substituted carbons not monoalkoxy, 20 protons; large complex multiplet ranging between 4.45 and 5.1, having its center of gravity at ~ 4.75, acetalmethine protons, 5.5 protons (theory 6.0). A spectrum produced in CDC13 reveals that the ratio of methyl protons / alkoxy / acetalmethine is

33.9 / 20 / 5.9. An exchanged spectrum d4-MeOD changes the ratio to 32.8 / 20 / 5.7, while a spectrum changed with dö-DOAC reveals that the ratio changes to 34.9 / 20 / 5.9. Oximation analysis of the hydrolyzed acetal at pH 3.5 in the presence of hydroxylamine indicates 96.4% of the theoretical acetaldehyde to be released, which indicates that not more than 20% of the 6th hydroxyl of the molecule is free OH.

Example 5:

A lemon drink is prepared at around 23 ° C, combining 6s 8 drops of a 1% solution of orange flavor in 95% ethanol and 14 ml of lemon syrup, bringing the volume up with water to that of a container of approximately 114 g of water. The orange flavor consists of orange terpenes containing 5% by weight of acet-

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8

aldehyde. The lemon syrup is prepared by adding 4.51 of a 67.5% solution of sucrose in water, 14 ml of a 25% by weight solution of sodium benzoate in water and 44 ml of citric acid 50% in water. The pH of this syrup is normally around 3.1. A third drink is prepared using orange terpenes containing 12% of 4- (l'-ethoxy) -ethoxymethyl-2-methyl-1,3-dioxolane as the orange flavor.

Out of a team of 5 professional specialists, 4 considered that the difference in flavor was small between the drinks, and the fifth judged that the drink fortified by the generator was better on a blind selection basis. In a new trial, the next day, with freshly brewed beverages, tried for 20-30 min of mixing, only one in five of the specialists was

capable of identifying the fortified drink on the basis of a blind selection.

5 Example 6:

Essaia)

Lemon drinks are prepared in the same way as in Example 5 using, in drink No. 1, an unfortified orange flavor, in drink No. 2, the same orange flavor but fortified. with 7.5% of 4- (l'-ethoxy) ethoxymethyl-2-methyl-1,3-dioxolaneet, in drink N ° 3,7,0% of l, 2,3-tris [(r-ethoxy ) ethoxyJpropane. We asked 4 professionals to classify the drinks in order of freshness, we get the following results:

Trial duration * '

Classification

Assayer 1

1-2 min

Drink 2> Drink 1> Drink 3

Assayer 2

2 min

Drink 2> Drink 1> Drink 3

Assayer 3

~ 2 mins

Drink 3> Drink 1> Drink 2

Assayer 4

~ 10 mins

Drink 2> Drink 3> Drink 1

* Time interval between mixing and tasting.

This test shows a predominant preference for fortified drinks.

Trial b)

Two orange drinks are prepared by the method described for test a, in which a fortified orange flavor is compared with 8% of 1,2,3-tris - [(1 '-ethoxy) ethoxy] propane to a drink without acetaldehyde or generator. As in Examples 5 and 6a, the drinks are prepared at room temperature, that is to say approximately at 23C. About 2 min after the preparation of the drinks, the 4 professionals declare that their preference goes to drinks fortified by the generator because of its fresh fruit effect.

Try)

Two orange flavored drinks are prepared as in test b. One drink has a flavor of fortified orange with 8% 1,2,3-tris- (1 '-ethoxy) ethoxy] propane and the other has no generator or acetaldehyde. The water used to prepare the drinks is pre-

25 cooled to 10 ° C and flavoring oil in 1% alcohol is added to the drink after mixing the lemon syrup. The 4 professionals still find the fortified drink in the generator 2 min after mixing it preferable as regards its effect of freshly squeezed juice. 2 professionals find the effect noticeable within 30 minutes.

Example 7:

Study of the hydrolysis of various acetals Test a)

35

4- (1 '-ethoxy) ethoxymethyl-2-methyl-1,3-dioxolane

The above-mentioned acetal (0.224 g) is dissolved in 50 ml of sulfuric acid diluted to pH 3.0. The absorption of the solution is measured by ultraviolet spectroscopy at 275 X, which gives the following results compared to the theoretical generation of this aldehyde. This test indicates that practically only the linear acetal portion of this molecule is released at this pH and at this temperature:

Duration

Trial 1

Trial 2

Trial 1

Trial 2

(min)

(theory 0.197)

(theory 0.175)

2

0.050

0.012

25.4

6.9

4

0.072

0.04

36.5

22.9

10

0.116

0.1

58.9

57.1

20

0.164

0.14

83.2

81.1

30

0.193

0.15

98.0

85.7

Trial b)

solubilized using 10% ethanol, the acetal indicated is subjected to 1,2,3-tris-1 (1-ethoxy) ethoxy] propane hydrolysis under various pH conditions.

In a similar way to test a, except that the acetal is The results are collated below:

Absorption

% of acetaldehyde generated

Duration

Trial 1

Trial 2

Trial 3

(min)

(pH 3)

(pH 3.5)

(pH3)

Trial 1

Trial 2

Trial 3

(theory

(theory

(theory

(PH3)

pH 3.5)

(pH 3)

0.297)

1.75)

0.35)

1

-

-

0.058

-.

-

16.6

9

631,056

Absorption

% of acetaldehyde generated

Duration

Trial 1

Trial 2

Trial 3

(min)

(pH3)

(pH 3.5)

(pH 3)

Trial 1

Trial 2

Trial 3

(theory

(theory

(theory

(pH 3)

pH 3.5)

(pH 3)

0.297)

1.75)

0.35)

2

0.033

-

0.061

11.1

17.4

4

0.083

-

0.090

27.9

-

25.7

5

-

0.046

-

-

26

-

10

0.202

0.077

0.173

68.0

44

49.4

20

0.285

0.121

0.260

95.6

69

74.3

25

-

-

0.280

-

-

80.0

30

0.307

0.15

-

103.0

86

-

37

-

0.158

-

-

90

-

Try)

In a manner similar to test a, the 1,2-di- (l'-ethoxy) propane is subjected to hydrolysis at various pHs in dilute sulfuric acid:

Absorption

Duration

Trial 1

Trial 2

Trial 3

Trial 4

Trial 5

Trial 6

(min)

(pH3)

(pH 3.1)

(pH 3.2)

(pH 3.4)

(pH 3.5

(pH4)

(theory

(theory

(theory

(theory

(theory

(theory

0.354)

0.347)

0.358)

0.35)

0.356)

0.366)

1

0.03

0.03

0.03

2

0.07

0.07

0.055

0.017

- •

0.005

4

0.15

0.145

0.114

0.041

0.068

0.012

10

0.33

0.327

0.274

0.128

0.125

0.034

20

-

-

-

0.252

0.209

0.076

30

-

-

-

0.030

0.255

0.119

40

-

-

-

-

-

0.155

Acetaldehyde generated (%)

1

8.5

8.6

8.4

-

-

2

19.8

20.2

15.4

4.9

-

1.4

4

42.4

41.8

31.8

11.7

-

3.3

10

93.2

94.2

76.5

36.6

-

9.3

20

-

-

~ 100

72.0

58.7

20.8

30

-

-

-

85.7

71.6

32.5

40

-

-

-

-

-

42.3

R

3 sheets of drawings

Claims (13)

631,056 2 1. Method for increasing the fresh natural flavor of a food product by incorporating an aldehyde to replace or supplement the aldehyde naturally present in this product, characterized in that this aldehyde is added in the form of a generator aldehyde chosen from the class consisting of: a) linear acetals of formula: R I R-i C-Ro I? 3 (CH-OC —OR4) n R-i C — Ro i R n being an integer between 0 and 5, b) vinyl ethers of general formula: Ì1 R— C —R9 I 0 \ CH / CH \ * 5 the substituents R, Rj, R2, R3, R.t and Rs in these formulas having the following meanings: R and R2 represent any combination of hydrogen, alkyl groups, alkoxy groups, acyl groups, carboxy groups and alkyl groups which are themselves substituted, R and R2 can be combined in a cyclic acetal structure, R, has the same meaning as R and R2, except that: when n = o, R cannot represent hydrogen, R3 is a hydrocarbon residue of 1 to 11 carbon atoms, R4 is a hydrocarbon residue of 1 to 7 carbon atoms, and Rs represents hydrogen or a hydrocarbon residue of 1 to 9 carbon atoms, this aldehyde generator being capable of releasing the desired aldehyde under the conditions of use. 2. Method according to claim 1, characterized in that the aldehyde generator is incorporated in a fruit-flavored drink. 3. Method according to claim 1, characterized in that the aldehyde generator is the product of the reaction between glycerol and ethyl vinyl ether. 4. Method according to claim 1, characterized in that the aldehyde generator is 4- (r-ethoxy) ethoxymethyl-2-methyl-l, 3-dioxolyne. 5. Method according to claim 1, characterized in that the aldehyde generator is l, 2-di [(l'-ethoxy) ethoxy] propane. 6. Method according to claim 1, characterized in that the aldehyde generator is a vinyl ether. 7. Method according to claim 1, characterized in that the aldehyde generator is 1,2,3-tris [(r-ethoxy) ethoxy] propane. 8. Method according to claim 1, characterized in that the aldehyde generator is l, 2,3,4,5,6-hexa - [(l'-ethoxy) ethoxyjhexane. 9. Linear acetal for implementing the method according to claim 1, characterized by the general formula: R I ■ r1-Ç-r2 Ro I (CH-O-C-OR4) n Ri-C-R., 1 2 R wherein the substituents have the meanings given in claim 1. 10. Linear acetal according to claim 9, characterized in that it consists of l, 2-di [(l'-ethoxy) ethoxy] propane. 11. Linear acetal according to claim 9, characterized in that it consists of l, 2,3-tri [(l'-ethoxy) ethoxy] propane. 12. Linear acetal according to claim 9, characterized in that it consists of l, 2,3,4,5,6-hexa [(l'-ethoxy) ethoxy] hexane. 13. Linear acetal according to claim 9, characterized in that it consists of l, 2-di [(l'-ethoxy) propoxy] propane.