WO1995010567A1 - Process for extraction of natural colours by means of bentonite - Google Patents

Abstract

Process for the extraction of colours from plants by mixing with bentonite, the plant having previously been homogenized by grinding and treatment having been given by ultrasonic means to assist the outflow of riboflavonoids.

Description

Process for extraction of natural colours by means of bentonite

The invention concerns a process for extracting colours from plants . There are well-known methods such as boiling, infusing whole plants or parts of them to obtain solutions that can be used to dye fibres.

Powders are also sold -on the market for preparing dye baths and extracts. Extracts are the most advantageous form being easy to store and use .

Extracts maintain organoleptic and dyeing characteris¬ tics intact and a sample obtained can be repeated a great many times . Extracts produce stronger and more brilliant colours as they are separated from secondary dyes.

But it is equally well known that the extracts at pre¬ sent offered for sale do not ensure colour fastness to heat and 1 i ght .

Generally speaking the chemical composition_ q__f_ powders and extracts is not s,tated, neither is there any indi¬ cation of the single components of the mixture, nor any toxicological analysis.

On the other hand there is growing interest in the en¬ vironment, in nature and in ecology.

Market requirements are increasingly directed towards natural products and colours in which the mixed compo- nents ensure stability, colour fastness, avoidance of toxicity, all to be supplied at competitive prices. The purpose of the above invention is to provide these advantages as will be explained below. Bentonite is known to be a natural mixture essentially comprising clay minerals such as marillonite and beidel- lite able to absorb large quantities of water and pro¬ ducing stable suspensions.

There is plenty of bentonite available especially in some regions . Subject of the invention is a process for continuous extraction of natural colours after a stage of homogeni¬ zing and ultrasonic treatment employing bentonites for separation of the stages containing riboflavonoids . The process is substantially carried out according to the following stages:

Homogeniza ion of the plant from which the extract is to be obtained by grinding it up and possibly adding H O. Varying the pH of the solution according to the type of plant. Ultrasonic treatment to break the cellular membranes to assist outflow of the riboflavonoids . Mixing with bentonite. The invention possesses evident advantages. An extract is obtained which, compared with-t-he- plant or with the powder, can be reproduced and is non-toxic. Use is made of raw materials that, both as regards the plants and the clays required, are amply available for an international market.

_The products obtained are better than at present and

Λ are produced at lower costs, offering both industrial and commercial advantages. Characteristics and purposes of the invention will be made still clearer by the example of its execution that is here given illustrated by a diagrammatic drawing.

Fig. I Layout of a typical production system.

The plant from which an extract is required is homogen- ized by placing it in the mill 11 of the installation ^' 10.

H O is added in the proportion of A litres of H 0 per kilo of plant .

The pH of the solution is 'brought to 8.1.

After 5-10 minutes the homogenized material passes into- an apparatus for ultrasonic treatment 12 where it remains for about 5 minutes and where the cellular membranes are broken up to assist outflow of riboflavonoids .

From the above apparatus 12 the pump 14 transfers the solution to the mixer 13 where it is mixed with bento- nite in the proportion of 1 kg. of plant material to 1 kg. of bentonite, this being done by strong shaking for about twenty minutes.

After this the mixture is left to stand and later the liquid on the surface is drawn off by the pump 15. Since the above invention has been described and explained as an example only in no way limited to this, and to show - A - its essential characteristics, it is understood that numerous variations may be made to it in accordance with industrial, commercial and other requirements ,and that it may include other systems and means without any departure from its sphere.

The application for patent rights therefore comprises any equivalent use of the concepts and any equivalent product executed and/or in operation according to any one or more of the characteris ics stated in the follow- ing claims .

Claims

C l a ims

1. Process for the extraction of colours from plants characterized in that use is made of bentonite.

2. Process as in claim 1, characterized in that it comprises the following main stages :

- homogenization of the plant by grinding,

- ultrasonic treatment of the homogenized material un¬ til the cellular membranes are broken down to assist outflow of riboflavonoids from the mixture,

- addition of bentonite to the mixture,

- removal of the liquid that rises to the surface.

3. Process as in claim 2, characterized in that H O is added during the homogeni- zing stage in the optimum proportion of 4 litres of

H O for every kilo of plant, the pH of the solution be¬ ing varied if needed according to the plant treated.

4. Process as in claim 3, characterized in that the pH is brought to 8.1.

5. Process as in claim 2, characterized in that bentonite is added to the mixture in the optimum proportion of 1 kilo of bentonite for every kilo of plant.

6. Process as in claim 2, characterized in that

- the homogenizing stage is conducted for 5-10 minutes,

- the ultrasonic treatment is given for about 5 minutes.

7. Process as in claim 2, characterized in that grinding is done in the blade mill (11), the ultrasonic treatment takes place in a special sonic apparatus ( 12), that the fluid so treated is taken by a pump ( 14) to a mixer ( 13) where" it is drawn off by a pump ( 15).