SK50012016A3 - Process for the preparation of a natural acid concentrate from grapes - Google Patents

Abstract

Disclosed is a method for preparing a natural acid concentrate from unripe grape berries that is stalked, ground and pressed. The sour grape juice obtained is preferred by the use of Saccharomyces cerevisiae wine yeast, thereby significantly reducing the carbohydrate content. After the fermentation step, the juice is clarified by settling and / or bentonite addition. Pyrosulphite or SO2 can also be used to improve color. To achieve a stable product, the preferential grape juice is concentrated to dry matter by 30-75% by evaporation of water at 35-100 ° C or by a combination of reverse osmosis and vacuum evaporation processes. The concentrate can be used as an oxidizer in food, ready-made meals, salads and beverages.

Description

Process for preparing a natural acid concentrate from grapes

Technical field

Manufacture of food products

BACKGROUND OF THE INVENTION

Thickened grape-based oxidants prepared from unripe grapes are not mentioned in the current literature.

White grape concentrate, which is suitable for sweetening beverages, is still on the market. The concentration value is 65 ° Brix. The concentrate also contains SO2. This product is made by vacuum evaporation from grape must.

In the current literature, oxidants are mentioned in the development of fruit-flavored products such as beverages, gelatin desserts, jams, jellies or sweets. These flavors and sweeteners are adjusted to achieve the desired taste and acidity. Lactic acid and acetic acid are most commonly used. Of natural acids, lemon juice or a concentrate thereof is used as a flavoring.

However, the taste of most products can be greatly improved by using a mixture of acidifying agents or other oxidizing agents. The use of a mixture of acidifying agents increases the taste profile. As shown in Table I, the fruits contain a mixture of acidifying agents, not just one acid. These fruits usually contain a total of 0.5 to 2.0% acid, except for tamarind, whose fiber contains a total of more than 10% acids.

Table I: Acids present in fruit

fruit Predominant acid Secondary acids Apple Malic acid (95% *) Tartaric acid, Fumaric acid apricot Malic acid (70% *) Citric acid, Tartaric acid cherry Malic acid (94% *) Tartaric acid grapes Malic acid (60% *) Tartaric acid grapefruit Citric acid Malic acid Guave Citric acid Malic acid Lime, lemon Citric acid Malic acid mango Citric acid Malic acid, Tartaric acid

orange Citric acid Malic acid peach Malic acid (73% *) Citric acid pear Malic acid (77% *) Citric acid pineapple Citric acid Malic acid raspberry Citric acid Malic acid, Tartaric acid Strawberries Citric acid Malic acid, Tartaric acid tamarind Tartaric acid Citric acid, Malic acid melon Malic acid (99% *) Fumaric acid

*% of total acids in fruits

As shown in Table I, malic acid and citric acid are the predominant acids in most fruits. What is interesting is how malic acid predominates. Even in the grapes most people associate with tartaric acid, malic acid is the dominant acid.

Description of the main acids in the food industry

Acid regulators E260 - E297 - They are dosed as additives to adjust the pH of the environment and the taste properties. These include lactic, malic, tartaric, citric, acetic, ... acidify, preserve, stabilize colors and dampen the growth of rotting bacteria. They are used in canned fruits, vegetables, jams, fruit drinks and juices.

Acetic acid (E260) - The most famous organic acids, naturally occurring in many fruits and fermented foods, found in vinegar. Acetic acid is available in liquid form and is highly corrosive at high concentrations. At present, they can be produced by FERM Entaco (natural acetic acid), or by synthesis, in foods mostly natural acetic acid is used. Acetic acid has a very intense specific pungent odor and taste, commercially used as a 6-10% solution. Acetic acid is used in many food products such as a natural preservative.

Citric acid (E330), - is a naturally occurring in fruit organic acid (first isolated from lemon), commercially produced by microbial fermentation of substrate carbohydrates. Citric acid is colorless and odorless, and exists in a crystal or crystalline form of powder, has a sharp and well pronounced acidic taste. Citric acid is well soluble in water and alcohol and is hygroscopic.

Malic acid (E296), - is a naturally occurring in fruit organic acid (first isolated from apples) and present in human metabolism (Krebs cycle), commercially produced by synthesis. DL malic acid is colorless and odorless and can exist in a crystal or granular form, has a strong acid taste very well enhancing the fruity taste, especially the citrus taste. Malic acid is well soluble in water. Limited volumes of L malic acid are commercially produced.

Fumaric acid (E297), - is naturally present in living cells of a chemical compound (various fungi), also produced in human skin when exposed to sunlight and also in some fruits and vegetables. Commercially produced by chemical synthesis from malic acid. It is a crystalline, odorless substance without hygroscopic and limited solubility in water.

Lactic acid (E270) is naturally found in many fermented foods and the human body's organic acid (first isolated from sour milk), produced commercially by microbial fermentation of carbohydrate substrates. Lactic acid is normally available in liquid form (50-80% concentration), a clear colorless to pale yellow solution. It has a specific sour taste and no strong odor, giving a well balanced, less sharp and nice acidity end product. Lactic acid is very soluble in water. Lactic acid may also be available in powder form

Tartaric acid (E334) is a naturally occurring in fruit organic acid (first isolated from tartar wine stone), commercially produced as a natural step in wine making. Tartaric acid is a colorless and odorless crystal, has a strong and sharp acid taste. Tartaric acid is well soluble in water

Succinic acid (E363) is a naturally occurring dicarboxylic acid found in most fruits and vegetables. Traditionally, it is produced by catalytic hydrogenation of maleic acid and acid anhydride, can also be extracted from fruit, or has recently produced bioconversions. Odorless, colorless, white crystalline solid which has a slightly bitter and acidic taste and is soluble in water.

Phosphoric acid (E338) is an inorganic acidifier obtained by a chemical reaction from rock phosphorus. This gives a very strong acid taste in low concentrations. It is commercially available in liquid form and most often 70 to 80% of the concentration. Phosphoric acid Food grade is a colorless clear liquid.

ACID FUNCTIONALITY IN VARIOUS FOOD PRODUCTS

Product E tag Form Taste and aroma Avg H to 1% solution solubility natural features Kys.octová E 260 The liquid vinegar 2.7 high Yes Increase. flavoring; increase pH controls and microl. contamination Kys.mliečna E 270 The liquid Soft, sour taste 2.4 high Yes* Zvýš.arOmy; increase pH controls and microl. contamination Kys.jablčná E 296 solid Acid, slightly sharp 2.3 high Not Zvýš.arómy; increase pH controls and microl. contamination Kys.fumarová E 297 solid Horkokyslá 2.1 low Not Zvýš.arómy; increase pH controls and microl. contamination; raising agent. Kys.citrónová E 330 solid Strong citrus 2.3 high Yes* Zvýš.arOmy; increase pH controls and microl. contamination; chelates. agent Kys.vínna E 334 solid Sour with wine taste 2.1 low Yes* Zvýš.arómy; increase pH controls and microl. contamination; raising agent. Kys.fosforečná E 338 The liquid sour 1.6 high Not Zvýš.arómy; increase pH controls and microl. contamination Kys.jantárová E 363 solid Horkokyslá 2.6 low Yes Zvýš.arómy; increase pH controls and microl. contamination

Grapes (Vitis vinifera L.)

The main constituents of grape must are water (around 80%), sugars (10-25%, acids (4-20 g / l), tannins and phenolic components (0,1%). The must also contains minerals (3-5 g) .1-1; especially potassium and calcium salts); nitrogenous substances; enzymes; vitamins; fats, waxes, oils.

Sugars are mainly represented by glucose and fructose.

The main acids present in the grapes are malic acid and vuma, which are mainly found in the flesh. Thanks to them the juice has a fresh - fresh taste and protects it from microbial decomposition. Grapes harvested early or ripened under very cold conditions have a high malic acid content. The grape must also contains small amounts of citric, succinic, oxalic, glycolic, ascorbic and acetic acid. The tannins and phenolic components found in juice are potent antioxidants and cause browning when processed unpretentiously.

The patent literature describes a process for the preparation of an oxidant comprising fumaric acid "Acidulent containing fumaric acid and dried natural juice solids" - US Patent 4,622,227 (1986). The patent describes the preparation of an oxidant with fumaric acid and natural juice with solid particles. Fumaric acid is added in an amount of at least 50% by weight based on the acidifying agent and natural juice in an amount of 5% by weight. The oxidant may also contain a sweetener in an amount of 2%.

Grape juice contains many kinds of different microorganisms. Yeasts and yeast microorganisms are the most represented. Juice infested with diseases or rotten berries contains, in addition to yeasts and yeast microorganisms, various harmful fungi and bacteria. The amount and proportion of microorganisms depends primarily on the health of the grapes. This whole mixture of microorganisms is called the spontaneous "microflora of juice" and has a great influence on the fermentation of the must and the quality of the wine. The microorganisms found in the juice are among the lower plants and are divided into yeast, bacteria and fungi.

Yeast is the cause of alcoholic fermentation of juice. They get into the juice from grape berries. The juice contains many genera and species of yeast, the most important of which is the genus Saccharomyces, which includes the noble yeast.

Saccharomyces cerevisiae belongs to the genus Saccharomyces. In pure culture, they are also called cultural yeasts. They are oval to elisive in shape and they ferment glucose, fructose, sucrose, amltose, galactose and arafinose to 1/3; do not ferment lactose. They produce 10-15% by volume of alcohol, at least 16-18%. This species is also mentioned in the literature under the synonym Saccharomyces vini; Saccharomyces ellipsoideus and Saccharomyces cerevisiae, var. ellipsoideus-.

SUMMARY OF THE INVENTION

The subject of the invention is a grape food acid-concentrate of natural acids with a high content obtained by concentrating grape juice from unripe grapes in a mixture or separately.

Unripe bunches of grapes of different varieties are shredded, the berries are ground and then pressed. The resulting grape juice, which is cloudy, has an acidic taste, a pH value of 2.4-3.2 and a refractometric dry matter of 8-15%. The yield of such unripe berries ranges from 55 to 70%, depending on the grape variety.

The resulting grape juice is clarified by settling and / or by the addition of bentonite. Pyrosulfite or SO2 can also be used to improve color.

The clarified juice is prefermented with Saccharomyces cerevisiae wine yeast, which significantly reduces the content of simple carbohydrates. The fermentation is carried out at a temperature of 12-30 ° C and stirring occasionally. By reducing the carbohydrate concentration to the desired value After fermentation, we obtain acidic grape juice with a carbohydrate content of 1 to 5%.

To achieve a stable product, the grape juice is concentrated to dryness by 30-75% by evaporating water at 35-100 ° C or by using a combination of reverse osmosis and vacuum evaporation. The resulting concentrate has a pH of from 2 to 2.7 and a refractometric dry matter of 60 75%. A acid content 20 - 35%

DETAILED DESCRIPTION OF THE INVENTION

Example 1:

The bunches of grapes of the Irsai Oliver variety were used. The fringes were chipped in a screw chopper, the berries were ground in a roller grinder, and the juice was then pressed on a Lancman water press.

120 l of grape juice were thus obtained from 200 kg of unripe grapes of the Irshai variety. This gave a yield of 60%. It was cloudy and slightly sour in taste. The pH of the fresh juice was 2.9 and the refractometric dry matter was 12%.

Fresh juice was fermented using Saccharomyces cerevisiae yeast at 30 ° C for 72 hours. The carbohydrate content of the grape juice before fermentation was 11% and decreased to 1.5% after fermentation. After settling, the preferred acid grape juice was clarified by microfiltration.

601 fresh juice was heated in a vacuum evaporator and evaporated at 75 ° C and concentrated to 65% refractometric solids. The resulting concentrate has a distinctly acidic taste, a slight caramel flavor, and a dark brown color with a final concentration of acids (28%) expressed as tartaric acid.

Example 2:

Bunches of grapes of the Bianca variety were used. The fringes were chipped in a screw chopper, the berries were ground in a roller grinder, and the juice was then pressed on a Lancman water press.

120 l of grape juice were obtained from 180 kg of unripe grapes. This yielded a yield of 66%. The pH of the fresh juice was 2.6 and the refractometric dry weight was 10%.

Fresh juice was fermented using Saccharomyces cerevisiae yeast at 32 ° C for 72 hours. The carbohydrate content of the grape juice before fermentation was 9.5%, after fermentation it was reduced to 1%.

Subsequently, the juice was clarified by the addition of bentonite and filtered on an alluvial filter.

The filtered juice was pre-concentrated to 22% refractometric solids using reverse osmosis and concentrated to 65% refractometric solids in a vacuum evaporator at a evaporation temperature of 45 ° C. The resulting concentrate has a distinctly acidic taste, a fruity flavor and a light green-brown color with a final concentration of acids (31%) expressed as tartaric acid.

The process described above for the production of thickened sour juice has been verified on a pilot scale of 500 liters of must. It is easy to implement under industrial conditions.

The prepared grape oxidant product is useful for acidifying various drinks and for flavoring food and ready meals.

Industrial usability

Claims (1)

Process for the preparation of a concentrate of natural acids from grapes, characterized in that the acid squeezed juice of different grape varieties in a mixture or separately to reduce the carbohydrate content is fermented using Saccharomyces cerevisiae yeast and the preferred juice is clarified and concentrated to dryness by 30-75% at 35 100 ° C or a combination of reverse osmosis and vacuum evaporation processes.