PROCESS OF VALORIZATION OF TOMATO POMACE

Abstract

The present invention relates to an integrated process for recovering tomato juice from tomato pomace as well as biologically dehydrating and stabilizing it. The innovative process developed involves four main steps: separation by dissolution in an aqueous matrix compatible with human feed, solid-liquid separation, filtration cake washing and thermal dehydration. The tomato juice resulting from the developed process is intended to be incorporated into the tomato concentrates of the tomato: processing industry. The dehydrated tomato pomace is a biologically stable product and can be used in ruminant and non-ruminant animal feed and as raw material for biotechnological and pharmaceutical applications.

Claims

1. Process of valorization of tomato pomace, characterized by being integrated, comprising the following sequential steps: a) Separation by dissolution in an aqueous matrix of the soluble sugars of the tomato pomace, carried out in a mixer with mechanical agitation (5), with a stirring speed ranging from 140 to 160 rpm and using an aqueous matrix, containing sugars and compatible with human feed, resulting from the washing of the filtration cakes of the tomato pomace from the filter press with membrane plates and capacity of thermal dehydration under vacuum (6), forming a suspension of tomato pomace; b) Solid-liquid separation of the tomato pomace suspension obtained in a), carried out in a filter press with membrane plates and capacity of thermal dehydration under vacuum (6) for obtaining tomato juice and filtration cakes; c) Washing of the filtration cakes obtained in b), carried out in the filter press with membrane plates and capacity of thermal dehydration under vacuum (6), through washing by forced intrusion of water; d) Thermal dehydration of the filtration cakes washed in c), carried out in the filter press with membrane plates and capacity of thermal dehydration under vacuum (6) with the use of a thermal fluid.

2. Process according to claim 1, characterized by the addition of the aqueous matrix compatible with human feed containing sugars, resulting from the washing of the filtration cakes in a ratio ranging from 0.5 to 2 kg of the washing solution per kg of dry pomace.

3. Process according to claim 1, characterized in that the residence period, of the tomato pomace in the mixer with mechanical agitation (5), is between 2 and 15 minutes.

4. Process according to claim 1, characterized in that the transportation and feed of the tomato pomace suspension to the filter press with membrane plates and capacity of thermal dehydration under vacuum (6) is carried out with a filter press feed pump of positive displacement indicated for suspensions with a solids concentration greater than 20% (9).

5. Process according to claim 1, characterized in that the filter press with membrane plates and capacity of thermal dehydration under vacuum (6) is equipped with flexible membrane plates made of material compatible with human feed.

6. Process according to claim 5, characterized in that the filter press with membrane plates and capacity of thermal dehydration under vacuum (6) is equipped with flexible membrane plates made of material compatible with human feed, alternating with plates of metal filtering surface.

7. Process according to claim 1, characterized in that the filter press with membrane plates and capacity of thermal dehydration under vacuum (6) contains polypropylene monofilament filtration screens with air permeability of between 1750 and 3500 dm.sup.3/(dm.sup.2.Math.min).

8. Process according to claim 1, characterized in that the filter press with membrane plates and capacity of thermal dehydration under vacuum (6) contains filtration nets made of material compatible with human feed with a mesh aperture of less than 1000 m.

9. Process according to claim 1, characterized in that the washing of the filtration cakes by forced intrusion is carried out with human consumption quality water in the ratio of 0.3 kg to 1.5 kg of water per kg of dry pomace, repeating the cycle of washing successively from 1 to 6 times, to a pressure not exceeding 7 bar.

10. Process according to claim 1, characterized in that the thermal dehydration of the filtration cakes uses, as thermal fluid, water at a temperature from 75 to 98 C. for a period between 60 to 360 minutes, with the filtration cakes being subjected to an absolute vacuum pressure comprised between 20 and 150 mbar.

Description

DESCRIPTION OF THE FIGURE

[0024] FIG. 1 shows the process diagram of the recovery of juice from tomato pomace and the thermal dehydration of the same. The tomato pomace obtained through the tomato concentrate producing process is stored in the conical tank (1) from which it is transported by the positive displacement pump indicated for suspensions with a solids concentration of more than 20% of the tomato pomace feed (7) to the mixer with mechanical agitation (5). After separation by dissolution in an aqueous matrix of the soluble sugars, the suspension is fed using a filter press feed pump of positive displacement indicated for suspensions with a solids concentration greater than 20% (9) into the filter press with membrane plates and capacity of thermal dehydration under vacuum (6). After the filtration, cakes are compressed by dilation under pressure of the flexible membranes of the filtration plates. The centrifugal pressure pump (10) allows the under pressure and closed-circuit circulation of the compression water of the filtration cakes. After filtration and compression of the filtration cakes, tomato juice is obtained and is then sent to the tomato juice storage tank (3). The washing of the filtration cakes is carried out with human consumption quality water stored in the water tank (2), which is pumped with the centrifugal water pump (8) into the filter press with membrane plates and capacity of thermal dehydration under vacuum (6). At the end of the cake washing operation, an aqueous matrix is obtained, after proper operation of the three-way valve (14), which is stored in the aqueous matrix storage tank for the dissolution separation step (4). The aqueous matrix is then fed with the aqueous matrix centrifugal pump (11) to the mixer with mechanical agitation (5). The dehydration of the pomace cakes is accomplished through the circulation of the thermal fluid in closed-circuit inside the filtration plates heated by the energy source (13).

[0025] The filter press with membrane plates and capacity of thermal dehydration under vacuum (6) may be equipped with a set of flexible membrane plates made of material compatible with human feed or with plates equipped with flexible membrane alternated with metal surface filter plates. This latter configuration allows better heat transfer by increasing the efficiency of the thermal drying.

[0026] After dehydration of the filtration cakes, the filter press with membrane plates and capacity of thermal dehydration under vacuum (6) is opened and the dehydrated pomace is conveyed for storage through the conveyor belt of the filtration cakes (12).

Example 1

[0027] A pilot test was performed with 147 kg of tomato pomace with 71% moisture as obtained at the exit of the tomato concentrate production process. The separation by dissolution in an aqueous matrix compatible with human feed, of the soluble sugars existing in the tomato pomace occurred in a mixer with mechanical agitation (5) with a stirring of 140 rpm for 7 minutes. 46 kg of the aqueous matrix resulting from the washing of the filtration cakes (obtained in a previous test) with a Brix degree of 1.3 Bx were added to the pomace in the mixer with mechanical agitation (5).

[0028] After the separation by dissolution in an aqueous matrix containing sugars, compatible with human feed, the tomato pomace suspension was fed to the filter press with membrane plates and capacity of thermal dehydration under vacuum (6) with a filter press feed pump of positive displacement indicated for suspensions with a solids concentration greater than 20% (9) at a constant pressure of 4 bar. Concave filtration plates with flexible membranes made of material compatible with human feed were used, which allowed the formation of filtration cakes with 4 cm of thickness.

[0029] Polypropylene monofilament screens with air permeability of 3279 dm.sup.3/(dm.sup.2.Math.min) were used as filter media.

[0030] After the filtration operation, 84 kg of tomato juice were obtained, with a Brix degree of 5.1 Bx and a total lipid concentration of 0.2 g/100 g, a saturated fatty acid concentration of 0.14 g/100 g, monounsaturated fatty acids of 0.02 g/100 g and polyunsaturated fatty acids of 0.03 g/100 g. These characteristics allowed the incorporation of tomato juice in the industrial process of tomato concentrate production.

[0031] The washing of the cakes was carried out by introducing 52.3 kg of human consumption quality water into the filtration chambers of the filter press with membrane plates and capacity of thermal dehydration under vacuum (6), with 3 washing cycles being performed by forced intrusion, obtaining an aqueous matrix compatible with human feed containing sugars with a Brix degree of 1.3 Bx.

[0032] The thermal dehydration was performed using hot water as the thermal fluid at 90 C. for 90 minutes by subjecting the filter cake to an absolute pressure of 80 mbar. At the end, 39.5 kg in dry mass of filtration cakes with 33% of moisture were obtained.

Example 2

[0033] A pilot test was performed with 162 kg of tomato pomace with 72% of moisture as obtained at the exit of the tomato concentrate production process. The separation by dissolution in an aqueous matrix compatible with human feed of the soluble sugars existing in the tomato pomace occurred in a mixer with mechanical agitation (5) with a stirring of 160 rpm for 6 minutes. 50 kg of the aqueous matrix resulting from the washing of the filtration cakes (obtained in the previous example 1) with a Brix degree of 1.3 Bx were added to the pomace in the mixer with mechanical agitation (5).

[0034] After the separation by dissolution in the aqueous matrix, compatible with human feed containing sugars, the tomato pomace suspension was fed to the filter press with membrane plates and capacity of thermal dehydration under vacuum (6) with a filter press feed pump of positive displacement indicated for suspensions with a solids concentration greater than 20% (9) at a constant pressure of 5 bar. Concave filtration plates with flexible membranes made of material compatible with human feed were used, alternating with plates of metal filtering surface.

[0035] This set of plates allowed the formation of filtration cakes with 2 cm of thickness. Filtration nets made of polyamide compatible with human feed with a mesh aperture of 800 m were used as filter media.

[0036] After the filtration operation, 89 kg of tomato juice with a Brix degree of 6.1 Bx and a total lipid concentration of 0.2 g/100 g, a saturated fatty acid concentration of 0.16 g/100 g, monounsaturated fatty acids of 0.01 g/100 g and polyunsaturated fatty acids of 0.02 g/100 g were obtained.

[0037] The washing of the cakes was carried out by introducing 54 kg of human consumption quality water into the filtration chambers of the filter press with membrane plates and capacity of thermal dehydration under vacuum (6), with 3 washing cycles being performed by forced intrusion, obtaining an aqueous matrix compatible with human feed containing sugars with a Brix of 1.3 Bx.

[0038] The thermal dehydration was performed using hot water as the thermal fluid at 85 C. for 180 minutes by subjecting the filter cake to an absolute pressure of 80 mbar. At the end, 43 kg in dry mass of filtration cakes with 16% of moisture were obtained. [0039] Lisbon, Jul. 2, 2018.