METHOD FOR EXTRACTING CAROTENOIDS FROM VEGETABLE MATTERS

Technical field

The present invention relates to a method for extracting carotenoids from vegetable matters. Background art

The byproducts of the industrial processing of some vegetable products (particularly horticultural products) are widely used; in particular, the byproducts of the processing of tomatoes (peels and seeds) are destined predominantly for zootechnical feeding, for composting and/or for disposal in a landfill. They are rich in carotenoids and in particular in lycopene, a substance of increasing cosmetic and nutraceutical interest (a neologism which combines the terms "nutritional" and "pharmaceutical" to indicate products that are derived from various nutrients which have many curative and/or therapeutic functions): investments in research into innovative methods for extracting and purifying lycopene, obtained from industrial recovery of waste material, can lead to considerable economic effects in the same primary sector.

The extraction of lycopene and other carotenoids that are commonly present in tomatoes and in their derivatives commonly occurs by using organic solvents which have a high environmental impact and obviously less than positive effects on the nutritional healthiness of the extracted products; the solvents most commonly used are: hexane, dichloromethane, acetone, ethyl acetate; they perform extraction effectively especially on lipophilic and therefore hydrophobic substances; lycopene has both the characteristics mentioned above and characteristics of poor solubility even by means of solvents such as SC-CO ₂ due to its high molecular weight (536.85 daltons), which causes problems in its diffusion through the cellulose membranes of the chromoplasts that contain it in the matrix of plant tissues.

This type of extraction technology has an interesting yield, although the extracted lycopene may be contaminated (to a minimal percentage) by the solvents used and therefore may. not be suitable for certain uses (for example for nutraceutical or pharmaceutical purposes). There are also methods for isolating lycopene from natural sources

(tomatoes and derivatives) which entail minimal degradation of the characteristics of the extract: in this manner, it is possible to obtain a natural raw material which is qualified for formulating new nutraceutical, pharmaceutical and cosmetic products. These methods are currently absolutely uneconomical, since they have extremely low yields which do not justify the provision of an appropriate industrial facility.

One of the main technical problems that has to be dealt with is linked to the rapid degradation of lycopene during storage. In particular, it is known from the existing literature that the main causes of the degradation of lycopene during tomato dehydration are isomerization and oxidation. The thermal treatment in general causes conversion from the all-trans form to various cis forms. Dehydrating fresh tomatoes by osmosis in fact causes neither isomerization nor loss of the initial lycopene; thermal treatments, instead, in addition to a total loss of lycopene, cause the appearance of cis forms associated with a decrease of the trans form.

The simultaneous presence of air increases oxidation phenomena. Disclosure of the invention The aim of the present invention is to provide a method for extracting carotenoids from vegetable matters which allows to obtain lower production costs with a satisfactory recovery of lycopene.

Within this aim, an object of the present invention is to provide a method for extracting carotenoids from vegetable matters which uses only non-toxic solvents and in particular does not require the use of

hydrocarbons.

Another object of the present invention is to provide a method for extracting carotenoids from vegetable matters in which degradation during storage is minimized. Another object of the present invention is to provide a method for extracting carotenoids from vegetable matters in which the stored vegetables are not subjected to oxidation processes caused by the presence of oxygen in the storage environment.

Another object of the present invention is to provide a method for extracting carotenoids from vegetable matters which has an extremely low environmental impact.

A further object of the present invention is to provide a method for extracting carotenoids from vegetable matters which has a bacteriostatic action on the treated substances. A still further object of the present invention is to provide a method for extracting carotenoids from vegetable matters which has a low cost, is relatively simple to provide in practice, and is safe in application.

This aim and these objects, as well as others which will become better apparent hereinafter, are achieved by the present method for extracting carotenoids from vegetable matters which consists in collecting and gathering any portions of interest of said vegetable matters which constitute the raw material, breaking down said raw material, performing an enzyme treatment with additional breakdown functions, dehydrating at least partially the broken-down compound, storing the at least partially dehydrated compound and extracting at least one carotenoid by means of cycles based on the use of supercritical CO ₂ as solvent.

Brief description of the drawings

Further characteristics and advantages of the invention will become better apparent from the following detailed description of a preferred but not exclusive embodiment of a method for extracting carotenoids from

vegetable matters, illustrated by way of non-limiting example in the accompanying drawing, wherein the only figure is a functional block diagram of the method according to the invention.

Ways of carrying out the invention With reference to the figure, the reference numeral 1 generally designates a method for extracting carotenoids from vegetable matters.

In the preliminary research which led to determining the steps of the method 1 and to the characteristics linked to the conditions and duration of said steps, industrial derivative products (pulps and concentrates) as well as waste from the industrial processing of tomato, having a higher than average degree of moisture and color, were analyzed in order to better assess the yield and difficulties in operation. The purpose of this research was to determine an ideal technology for extracting lycopene.

The makeup of the carotenoids that are present in tomatoes and in their derivatives is substantially as follows: lycopene 85-90% of the total; α, β, Y, ξ carotene, phytoene, phytofluene, neurosporene and lutein (in decreasing order of percentage on the total).

The distribution of the main pigments (lycopene and carotene) in the fruit follows this pattern: lycopene is concentrated (>90%) proximate to the tissues of the pericarp, while carotene is more concentrated in the tissues that constitute the seed spaces of the berry and in any case in the endocarp thereof.

In order to optimize the content of lycopene and of the other carotenoids that are present in the final dry powder, it is possible to use conveniently raw materials that originate from cultivars or varieties for industrial use with a high content of carotenoids (especially lycopene).

The extraction method 1 consists in collecting and gathering any portions of interest of said vegetable matters which constitute the raw material; in particular, it can be convenient to associate with industrial processing waste 3 (such as for example peels and seeds) a certain amount

of fresh tomato 4 (and/or respective derivatives, such as pulps, preserves and the like).

In practice, the purpose of this collection is to provide a heterogeneous mix 5 of peels, seeds, pericarp tissue and other derivatives of tomatoes.

The collection and gathering step 2 also comprises an optional preliminary selection thereof which is intended to reject the portions with a low content of carotenoids and/or select vegetable products which belong to a cultivar which is particularly rich in the carotenoid that one wishes to select.

This heterogeneous mix 5 must then be subjected to a breakdown step

6, which consists in completely breaking and homogenizing,, by shredding, the vegetable matrix (the mix 5) in order to obtain a substantially creamy derivative 7 with an average particle size substantially not greater than 1 mm.

The creamy derivative 7 must then be subjected to an enzyme treatment 8 which has additional breakdown functions.

The enzyme treatment step 8 can comprise a preliminary placement of the creamy derivative 7 (optionally with the addition of water for better processability) in a hermetic tank, with subsequent introduction therein of a preferably pectolytic enzyme (as an alternative, enzymes of the cellulose type may also be suitable for treatment in analysis) which facilitates cell breakdown.

According to an embodiment which is particularly effective from a practical and application viewpoint, the hermetic tank is under continuous agitation: this practice can be achieved by using a tank which is controlled by a suitable agitator or industrial vibrating device.

Positively, it is preferable to maintain within the hermetic tank an atmosphere which is modified by means of suitable streams of nitrogen N ₂ . The pectolytic enzyme that is used generally in the enzyme treatment

step 8 is of the type of pectinase and is typically present with a concentration between 10 and 250 mg of enzyme per kilogram of vegetable matrix: in particular, optimum results are achieved with concentrations between 50 and 150 mg/kg. The enzyme treatment step 8 is performed generally by keeping the temperature substantially between 30 and 80 ⁰ C (according to a preferred solution of application, from 40 to 60 ⁰ C) for a time generally comprised between 1 and 5 hours (preferably approximately 3 hours).

After enzyme breakdown 8, a step 9 for at least partial dehydration of the broken down compound 10 is convenient.

The dehydration step 9 comprises typically a first cycle 11 , known as dewatering cycle, to eliminate a certain fraction of the water, for example by centrifugal separation, and a second drying cycle 12.

The liquor, i.e., the liquid removed from the broken down compound 10 being treated during the centrifugal separation 11 of the dewatering cycle, is conveyed toward the hermetic tank within which the enzyme treatment 8 occurs: in practice, since this liquid is particularly rich in enzymes, it is convenient to recycle it in order to utilize fully the enzymes being used. One possible system for industrial centrifugation (decanter) used in the method 1 is constituted by a GEA/Westfalia/Alfa Laval/Pieralisi decanter with a δ RPM of 15-20, an RPM rate of 4500 and a ratio between input solid and liquid of 1/3 (of course, other similar apparatuses can be used instead of the one cited here). At the output of the decanter, the solid cake 11a that is obtained typically has a moisture content of approximately 70% and a high content of carotenoids.

According to a first embodiment, the drying cycle 12 is of the type known as fluid bed drying, in which the air temperature is comprised typically between approximately 130 and 180 ⁰ C (in particular, the best

results are achieved with a temperature comprised between 140 and 160 ⁰ C).

According to a second embodiment, the drying cycle 12 is of the type known as drum drying, in which the steam temperature is comprised typically between approximately 10 and 160 ⁰ C (in particular, the best results are achieved with a temperature comprised between 120 and 140

⁰ C).

According to a third embodiment of particular interest in practice and in application, and therefore a preferred embodiment, the drying cycle 12 is of the type known as belt drying, in which the air input temperature is comprised typically between approximately 65 and 110 ⁰ C (in particular, the best results are achieved with a temperature comprised between 75 and 95 ⁰ C).

At the end of the dehydration step 9, a step 13 is performed for storing the at least partially dehydrated compound 14.

The step 13 for storing the compound 14 provides for its arrangement within an appropriately provided hermetic container, which is adapted to prevent the exchange of air and the access of light.

The material stored in the step 13 is then subjected to the actual extraction 15 of at least one carotenoid by means of cycles based on the use of supercritical CO ₂ as solvent.

The step 15 for extracting at least one carotenoid (particularly lycopene) by means of cycles based on the use of supercritical CO ₂ as solvent consists in compressing the carbon dioxide by means of a suitable pump above its critical pressure, in heating it above its critical temperature in a respective heater, producing supercritical CO ₂ : at this point, it is possible to subject to a stream of supercritical CO ₂ the vegetable matter previously subjected to the initial steps of the method 1 to extract the carotenoid 16 of interest: this may be present in the form of oleoresin with a high concentration of said carotenoid.

According to an applicative embodiment of particular practical interest, between the breakdown step 6 and the enzyme treatment step 8 there is an intermediate step for suspending in water the creamy derivative 7 obtained with the breakdown, with a ratio of creamy derivative 7 to water comprised between 3/2 and 1/2 (in particular, excellent results are achieved with a ratio of 2/3 and 1).

Although supercritical fluids are very hot and industrial extraction must consider the cost of production and of the corresponding safety and protection of the environment, CO ₂ is an ideal supercritical fluid for extraction, because it is inexpensive, can be obtained easily and has a lower critical temperature and pressure than other fluids, as well as a lower latent heat of evaporation. The main advantages of supercritical CO ₂ are listed hereafter.

The extraction capacity of supercritical CO ₂ depends on the density of the liquid, on the operating conditions (pressure and temperature), which can change its solvent properties and provide selective extraction. Since permeability is high, the extraction time can be considerably shorter than required in the process for extraction with an ordinary solvent.

CO ₂ is odorless, non-toxic, does not damage the ozone layer and does not contaminate the end products and the environment. As a consequence of its limited or nonexistent toxicity, the residual material can be recycled without any treatment.

The operating temperature is close to ambient temperature, particularly suitable for the treatment of heat-sensitive substances, which would be broken down by using thermal treatments. The high efficiency of extraction and the quality of the resulting product, moreover, cannot be achieved with other extraction methods.

Supercritical CO ₂ is inexpensive, does not burn and does not explode, eliminating the typical danger of extraction with organic solvents (hydrocarbons).

The use of supercritical fluids (SFE, Supercritical Fluid Extraction) to find alternatives to classical extraction methods gives a prominent role to carbon dioxide, which in the supercritical phase assumes the characteristics of a nonpolar solvent and is comparable to n-hexane; with this method it is therefore possible to extract nonpolar compounds from solid matrices. The advantage of this technique is that at the end of the extraction, the solvent, carbon dioxide, is removed in the form of gas, allowing to recover the concentrated extracted compounds.

Tests for industrial pretreatment to make the lycopene content present in the products being considered available for extraction by SC CO ₂ (SCFE) have been performed on a representative sample of product originating from the tomato processing industry.

The process for extraction with SC CO ₂ has an extremely low environmental impact and does not entail, as already mentioned, the production of wastewater or byproducts to be disposed of, and it is possible to contain at negligible values the consumption of CO ₂ during the process.

The treated raw material and the extracted product are further free from any contaminant due to the process (organic solvents or others) and indeed are partially "purified" by the treatment, since CO ₂ in the supercritical phase also has a bacteriostatic action.

The efficiency of the supercritical extraction process depends on the chemical-physical characteristics of the matrix being treated: the presence of water in fact has a negative effect on the solvent power of carbon dioxide.

It has thus been shown that the invention achieves the intended aim and objects.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

All the details may further be replaced with other technically equivalent ones.

In the exemplary embodiments shown, individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other exemplary embodiments.

Moreover, it is noted that anything found to be already known during the patenting process is understood not to be claimed and to be the subject of a disclaimer.

In practice, the materials used may be any according to requirements without thereby abandoning the scope of the protection of the appended claims.