DD254879A1 - PROCESS FOR CONDUCTING RED PRAYING - Google Patents

Abstract

The invention relates to a process for the enzymatic liquefaction of beetroot. According to the invention, the beets are blanched, quenched, crushed and the dye-containing juice is squeezed out. The dye-free Pressrueckstand is then pretreated with the addition of alkaline or acidic reagents at a given temperature-p H value time regime and then hydrolyzed with a cell wall degrading enzyme complex under renewed p H value setting. As enzyme complexes pectinases / macerases and optionally cellulases / hemicellulases are used. The resulting liquefied Pressrueckstand is worked up in a conventional manner and optionally mixed with the dye-containing press juice. The products according to the invention are applicable in the food industry and dietetics.

Description

Field of application of the invention

The invention relates to a process for the enzymatic liquefaction of beetroot (Beta vulgaris var. Conditiva Alef.). The liquefied beetroot products produced according to the invention can be used in the food industry and dietetics.

Characteristic of the known technical solutions

Beetroot (beetroot) is a valuable agricultural or horticultural raw material, which is mainly processed into sterilized preserves and pressed juice. Complete industrial utilization of the edible portion of beetroot has so far only been possible in lumpy form. So far, it has not been possible to enzymatically macerate or liquefy beetroot in contrast to most other types of fruit and vegetables. The causes of this difficult enzymatic vulnerability of the cell wall material of beetroot are unknown.

The juice which can be isolated by pressing beetroot with separation of the press residue has a dry matter content of more than 9%, a relatively high content of sugars and micronutrients (ζ Β, sucrose, potassium, nitrate, chloride) as well as being particularly valuable Ingredient the red dye betanin. The Betanin, which occurs in a concentration of about 1% in the dry matter, can be used in an enriched form for coloring food. Products from beetroot are attributed to certain physiological effects, for example a "blood-forming effect" or an "anti-tumor effect". A secure nutritional and dietary effect have the fibers contained in the cell wall material (cellulose, hemicelluloses, pectin, lignin). However, these are separated as pressed residue practically completely in the juice extraction.

Beetroot are only partly maceratable or liquefiable by the usual technological methods by pectinolytic enzymes (pectinases / macerases) and / or cellulolytic / hemicellulolytic enzymes (cellulases / hemicellulases). In the DD-WP 84317 it is shown that chips from beetroot are attacked only in the blanched state and with increased enzyme dose with the macerase preparation ROHAMENT P and other microbial pectinolytic enzyme preparations only to a small extent. Even when using the activated enzyme complex from red ripe tomatoes only partial macerates can be obtained. Similar results are also known from the scientific literature. Although treatment of beetroot mash increases the yield of pressed juice only slightly, the release of valuable ingredients from the plant tissue can be improved. Thus, an enzyme preparation named SPS-Ase, which possesses pectinase, pectinesterase, cellulase, hemicellulase and protease activities, has been proposed for the isolation of the dye from beetroot (DD-WP 208821 and 213240). Also in the preparation of a juice concentrate from beetroot enzymatic de-pectinization for viscosity reduction in the Preßsäften before ultrafiltration is recommended (DE-OS 3229345), on the other hand, the dye content of betanin preparations can be improved if prior to concentration of the juices or before their conversion to dry products fermentation the sugar is made by yeasts or other microorganisms (FR-PS 2399467, CS-PS 222529). Furthermore, a lactic acid fermentation of both mash and pressed juice from beetroot to improve the nutritional value is proposed (DE-OS 2001 874). In all these biotechnological processes, complete liquefaction of beetroot is neither achieved nor desired.

The currently practiced technology for obtaining juice from beetroot usually does not provide for enzyme use. The washed, blanched, cleaned and shredded beetroot are squeezed directly into pack, screw or horizontal presses. In this way, up to 80% fiber-free juice can be obtained. The Preßrückstand, which still contains a high proportion of low molecular weight ingredients and virtually all of the macromolecular constituents of the cell wall material or fiber, is discarded or used as animal feed.

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By intensive grinding or other mechanical comminution of the mash or the press residue from beetroot sedimentation-stable juice products can not be obtained.

Object of the invention

The aim of the invention is to overcome the identified shortcomings of a whole fruit processing of beetroot and show conditions of a pretreatment of the cell wall material or Preßrückstandes that allow complete liquefaction of the entire edible substance.

Explanation of the essence of the invention

The invention has the object of demonstrating process conditions under modification of the currently customary technology, in which it is possible to change the cell wall material or the pressing residue of beetroot so that they can be enzymatically completely macerated or liquefied.

It has now been found that this is achieved when the substantially dye-free Preßrückstand beetroot first with the addition of alkaline or acidic reagents at temperatures between 20 and 100 ⁰ C, preferably from 50 to 90 ⁰ C, during an exposure time of 0 , 25 to 24 hours, preferably between 0.5 and 2 hours, and pretreated at pH values greater than 8.0 or less than 2.0 and then, after a pH adjustment to 4.0 to 8.0, is preferably hydrolysed to 4.5 to 6.5, with a cell wall degrading enzyme complex of pectinases / macerases and optionally cellulases / hemicellulases at temperatures of 20 to 60 ⁰ C, whereupon the resulting liquefied pressed residue in a conventional manner pasteurized or sterilized, happens and optionally mixed with the dye-containing pressed juice

Sodium or potassium hydroxide solutions and sodium carbonate solutions are preferably used as alkaline reagents, and dilute mineral acids, preferably hydrochloric acid, can be used as acidic reagents. Suitable pectolytic enzymes are endo-type pectin polymerases, polygalacturonase (EC 3.2.1.15), pectin lyase (EC 4.2.2.10) and pectate lyase (EC 4.2.2.2.). The presence of pectin esterases (EC 3.1.1.11) is not required if pretreatment has occurred at strongly alkaline pHs. Particularly suitable as hydrolysing cellulolytic enzymes are cellulase preparations which have high C-r and C "activities as well as hemicellulose (araban, galactan, xylan, clucomannan, galactomannan, xyloglucan) cleaving activities.

The decisive step of the invention is a strongly alkaline or strongly acidic chemical pretreatment of the press residue from beetroot prior to enzymatic liquefaction. It has been found that the effect of the pretreatment can be enhanced if this takes place at elevated temperatures. At the same time, the effectiveness of the pretreatment according to the invention increases with increasing pH above pH 8.0 or with decreasing pH below pH 3.0 and with increasing exposure time.

Prior to the chemical pretreatment according to the invention is advantageously carried out the pre-cleaning (washing), blanching, peeling and crushing the beetroot. The pre-cleaning must be carried out gently, so that the tubers are mechanically not damaged as possible, so that premature discharge of the dye ("bleeding") is avoided., Blanching is required to inactivate disturbing plant-own enzymes.

Subsequently, the crushed, z. B. shredded beetroot squeezed in the usual pressing system and optionally with water nachextraiert in a known manner. The pressed juice contains most of the betanins and especially the soluble minerals, low molecular weight compounds, proteins and carbohydrates.

It is known that the valuable red dye of beetroot is unstable at elevated temperature or at high pH changes. The separation and separate work-up of the dye-containing pressed juice allows both a renewed mixing with the liquefied Press residue to a liquid whole fruit product as well as its separate further processing to a dye preparation in a conventional manner. In addition, it is possible by the steps according to the invention, the high proportion of nitrate and optionally further undesirable ingredients from the pressed juice in a known manner, for example by ultrafiltration or dialysis, separate.

It has proven useful after such cleaning steps to concentrate the juice in a vacuum.

After the separation of the pressed juice and the chemical pretreatment of the press residue according to the invention from beetroot under the alkaline or acidic conditions, the pretreated product is partially neutralized to a pH at which the enzymes can exert their effect. If the essential active components of the enzyme preparations, polygalacturonates and / or pectin lyase and cellulases / hemicellulases are, should be adjusted to a pH as possible between 4.0 and 5.0. If, on the other hand, pectate lyase is used, the pH should be above 6.0. An excessively high pH in the enzymatic liquefaction in the presence of pectate lyase is impossible because most commercially available cellulase / hemicellulase preparations are only slightly active at pH values above 6.5. It has surprisingly been found that the pressing residue of beetroot chemically pretreated according to the invention can be macerated completely with pectinolytic and cellulolytic / hemicellulolytic enzymes or liquefied to form hysteria. According to VORAGEN and PILNIK (Liquid Fruit, 48, p. 261 [1981]), maceration is understood to mean a limited pectin degradation, mainly of the middle lamella, by the action of polygalacturonase or pectate lyase. Here, the compact plant tissue is broken down into single cells or cell aggregates to viscous macerate. In contrast, the process of liquefaction in addition to degradation of the pectin by polygalacturonase (possibly in combination with

Pectinesterase) and / or by pectin lyase to a partial hydrolysis of the cellulose by reaching cellulases. Depending on the degree of dissolution of the cell wall material fully liquefied products of different viscosity are obtained. In this hydrolysis, however, a complete decomposition of the cellulose polysaccharides into glucose and cellooligosaccharides is not sought. As already stated, the enzymatic processes of maceration or liquefaction in beetroot that can be carried out in almost all other types of fruit and vegetables are not readily achievable. It must be assumed that the cause of this complicated enzymatic vulnerability lies in the structural peculiarities of the red-beet cell wall polysaccharides.

It has been shown that in the chemical pretreatment of beetroot according to the invention, substantial changes take place in the pectin component. The hydrolysis of the methyl ester bonds ("deesterification") of the pectin with liberation of methanol with simultaneous formation of free carboxyl groups in the galacturonan molecules takes place particularly under strongly alkaline conditions. As a result of the consumption of lye in this reaction, the originally set pH shifts in the press residue Towards the neutral point, partial or extensive deacetylation of the pectin occurs.The pectin substances in beetroot are relatively highly acetylated.The maximum degree of acetylation in pectin can be 2. In this case, all free hydroxyl groups on the carbon atoms are 2 and 3 of each galacturonic acid unit in the pectin molecule is esterified with acetic acid REXOVA-BENKOVA and coworker (Collect.

Chem. Commun. 42, p 3204 [1977]) found in model experiments that with increasing degree of acetylation, the hydrolysis rate of pectic acid with polygalacturonase greatly reduced. The degree of acetylation of the pectin component in beetroot is around 1, as our own studies showed.

The degree of acetylation was determined by means of the hydroxanoic acid method according to Mc COMB and Mc CREADY (Analyt Chem 29, page 819 [1957]). After pretreatment, the degree of acetylation is lowered to values between 0.7 and less than 0.3. There is a direct correlation between the degree of acetylation of the pectin after the pretreatment and the effectiveness of the pectinases and cellulases in the subsequent enzymatic treatment. Alkaline pretreatment is more effective in terms of deacetylation. On the other hand, a decrease in the degree of acetylation could not be effected by lactic acid fermentation.

It is essential that a partial or extensive enzymatic hydrolysis of the pectic substances in the middle lamellae and primary cell walls of the cell wall material is the prerequisite for the cellulose in the inner cell wall layers subsequently being depolymerizable by cellulolytic / hemicellulolytic enzymes.

After liquefaction, the inactivation of the enzymes takes place and optionally a fine pass of the product. The liquefied cell wall material can be further processed into secondary products. For example, mixing with the separately processed dye concentrate to sedimentation stable, pulpy, drinkable whole fruit products.

In addition, the liquefied press residue can be used without mixing the dye-containing pressed juice as a food additive or as a dietary fiber in dietetic preparations.

The method according to the invention is explained in more detail below by the exemplary embodiment:

embodiment

Washed beetroots are blanched for 10 min in a boiling water bath, then peeled and roughly grated into a mash. By means of a screw press, from 10 kg of this mash, 4.601 juice is separated, which has a dry matter content (TM) of 11.0%, a pH of 6.71 and an extinction of 0.480 (at 540 nm in a dilution of 1: 100) , The press residue stirred with warm water is squeezed again (9.851, TM = 5.8%, pH = 6.94 and extinction = 0.204). The juices are combined and concentrated in vacuo to 2.0 oil (TM = 50.1, pH 5.80, and absorbance = 1.90). The largely dye-free cell mass Preßrückstand (3.70 kg) is stirred with 2.801 water and divided into 5 portions of 1.30 kg each. After addition of 50 or 25 ml of 2N hydrochloric acid (Experiments A and B) or of 50 or 100 ml of 2N sodium hydroxide solution (Experiments E and D) or without addition (Experiment C) is 1 h at 7O ⁰ C under pre-treated with occasional stirring. Subsequently, the pretreated products are adjusted to a pH of about 4.5, made up with water to 1.50 kg and 1 h at 45 ⁰ C with 1% of Mazerasepräparates ROHAMENT P and 2% of a highly active Cellulasepräparates treated. After inactivation of the enzymes in the boiling water bath, the intermediates thus prepared are characterized (Table 1).

Whereas in experiment C a high proportion of non-passable residue remains and in experiment B only a partial digestion is achieved, it is possible after an intensive acidic (experiment A) or alkaline pretreatment (experiments E and D) of the cell mass of beetroot, this subsequently completely liquefied with suitable enzyme combinations. From the conditions chosen here, the alkaline pretreatment proves to be effective. The intermediate is fluid, while the intermediates D and Aviskos or highly viscous-mazeratartig. This is also evident in the flow times of 50 ml of intermediate product from the flow cup according to DIN 53211 (nozzle 3 mm).

From a proportion of the non-passed intermediates, an alcohol-insoluble substance (AUS) is prepared containing the insoluble in 65Vol .-% ethanol and macromolecular constituents. In the AUS, the water binding capacity is determined by the capillary suction method according to BAUMANN (G-I-T.-Fachz., Lab. 11, S. 540 [1967]) and the degree of acetylation. As the proportion of non-passable residue, the flow time, the yield of AUS and the water binding capacity show (Table 1), there is a relationship between the achieved Entacetylierung by the chemical pretreatment and the enzymatic digestion of the cell wall material of the Pressrückstandes.

Table 1

Characterization of enzymatically treated cell mass intermediates from beetroot (after acidic or alkaline pretreatment)

Experiment pH value after intermediate after enzymatic treatment

Pre-treatment - non-passable lung residue

A B C D

1.4 2.4 7.2 9.2 11.2

0 28.8

50.4 0 0

Flow time Yield Acetyherungs- WBK OUT Degree [g of water / [min / 50 ml] [%] 100g Pro domestic product] 17.10 2.35 0.68 19.34 n.d. 2.80 0.84 27.67 n.d. 3.27 0.87 44.63 3.18 2.27 0.51 17.55 0.23 1.81 0.30 - 8,43

AUS = alcohol-insoluble substance; WBK = water binding capacity;

n. b. = Not determinable due to excessive viscosity.

When mixing the intermediates A, D and E with 40 ml of the juice concentrate sedimentation stable whole fruit products are obtained with different viscosity.

Claims (3)

claims: 1. A process for the enzymatic liquefaction of beetroot after previous gentle blanching, peeling and crushing of beetroot and squeezing the dye-containing η juice and separate workup of Preßrückstandes, characterized in that the substantially dye-free Preßrückstand initially with the addition of alkaline or acidic acting reagents at temperatures between 20 and 10O ⁰ C, preferably from 50 to 90 ° C, during an exposure time of 0.25 to 24h, preferably between 0.5 to 2 h, and at pH greater than 8.0 or pretreated less than 2.0 and then after a pH adjustment to 4.0 to 8.0, preferably 4.5 to 6.5, with a cell wall degrading enzyme complex of pectinases / macerases and optionally cellulases / hemicellulases at temperatures from 20 to 60 ⁰ C hyrdoiysiert, whereupon the resulting liquefied pressed residue in a conventional manner pasteurized or sterile isiert, happened and optionally mixed with the dye-containing press juice. 2. The method according to claim 1, characterized in that as alkaline-acting reagents preferably dilute sodium and potassium hydroxide solution and sodium carbonate solution and as acidic reagents diluted mineral acids, preferably hydrochloric acid, are used. 3. The method according to claim 1, characterized in that as pectinases / macerases pectin of the endo-type, preferably polygalacturonase, pectin lyase and / or pectate, and as cellulotytic enzymes cellulases, preferably with high C ₁ - and C _x activity, and hemicelluloses cleaving enzymes of microbial origin can be used.