1

Valorisation of tomato processing by-product by extraction of an

oleoresin rich in lycopene

Matilde de Portugal da Silveira Henriques de Freitas1, José Santos1, Renato Carvalho 1Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal

Abstract

The main goal of this work was to study and evaluate the feasibility of the extraction of a lycopene rich

oleoresin from the by-product of the tomato processing industry. The physicochemical characterization of the

by-product (tomato pomace) and of the resulting extracts was conducted.

The available drying technologies were assessed, in order to achieve biological stabilization. An industrial dryer

was selected taking into consideration the pomace analysis results and the end-product specifications. After

careful examination of the supplier’s proposals for this equipment (suppliers A, B and C), the technical-

economical assessment of the investment was calculated, considering the proposal of the supplier A.

For economic evaluation, three scenarios were considered to estimate economic indicators. For the pessimistic

scenario, it was obtained an internal income tax (IRR) of 11% and a payback-time of 3 years. For the

intermediate scenario, the payback-time is 2 years and the IRR is 53%. For an optimistic scenario, the IRR is

308% and the investment is replaced in the first year of production.

Key-words: tomato, pomace, lycopene, oil, oleoresin, industrial dryer, extraction, extract

1. Introduction

Tomato pomace

Tomato is one of the most important crops in the

world, with an annual production estimated at 182

million tonnes per year (Food and Agricultural

Organization, 2017). Though it is widely consumed

as a fresh fruit, around one third of tomato

consumption is through processed products such

as tomato paste, tomato sauces, ketchup, etc. (Ries

et al., 1962). The revenue for the tomato

processing industry was evaluated at 5.2 billion

USD in 2017/118. (Tomato News, 2019)

The processing of tomato consists in the removal

of seeds, skins and any other hard substances.

Thus, the transformation process results in a by-

product called pomace that makes up to 2-13% of

the ripe tomato (Del Valle et al., 2006; Ventura et

al., 2009). The composition of tomato pomace

varies according to the cultivar, processing

parameters and location. Although it is currently

used as animal feed, tomato pomace represents an

underrated source for added value components.

The seeds have a considerable fat content for

vegetable oil extraction and the skins are

extremely rich in lycopene (Del Valle et al., 2006).

Lycopene

Lycopene is a red pigment carotenoid with health-

related benefits (Story et al., 2013; Gajowik et al.,

2016). It has a great antioxidant activity and a

crucial role in the biosynthesis of other

carotenoids. Over the last few years, the demand

for organic lycopene has grown due to its

anticancer, anti-inflammatory and radio protective

properties (Del Valle et al., 2006). Lycopene

(C40H56) is an unsaturated hydrocarbon, with 11

conjugated and 2 unconjugated bonds. Because of

its non-polar nature, it is insoluble in water and

soluble in organic solvents such as acetone, hexane

and petroleum ether.

2

Figure 1 – Molecular structure of lycopene isomers.

The market for lycopene rich products comprises

the food, cosmetic and pharmaceutical industries

(Carotenoids Market Size, Share & Trends, Global

Industry Report, 2025). Most common

formulations include oleoresins, crystals or

powders. Oleoresin is widely available since lipid

solubilisation enhances its bioavailability (Zelka et

al., 2001).

The red pigment accounts for approximately 80-

90% of all carotenoids in tomatoes. Lycopene is a

light and heat sensitive molecule, very susceptible

to degradation. It can assume cis and trans

configurations. The first has a greater

bioavailability and solubility and the second is

more stable (Benítez et al., 2018). In the fresh fruit,

trans configuration is more predominant but

transformation processes enhance the

isomerization to cis (Honeste et al., 2011). High

temperatures, inherent in many industrial

bioprocesses, like bleaching, pasteurization,

cooking, frying, preserving, drying and dehydration

are proven to catalyse these reactions (Xianquan et

al., 2005).

Given its economic interest for numerous

industries, studies have been conducted to

optimize the extraction from residues of tomato

production. Extraction of lycopene from tomato

pomace or skins only, with organic solvents is the

most popular method, leading to high recovery

yields. The optimization of extraction parameters

such as solvent choice, particle size, temperature,

extraction time and the existence of pre-treatment

processes, has been investigated by several

authors. Although several methods and extraction

operating conditions are described in the

literature, it is not possible to compare data due to

a wide range of parameters affecting the results.

Variants as the origin of the pomace, the solvent

choice, time, temperature and quantification

method prevent proper comparison of values.

In addition to extensive attempts to optimize

extraction operative conditions, many have sought

to apply pre-treatment processes to tomato

pomace. The results obtained by Zuorro et al.

(2011) support the use of cell degrading enzymes

for greater lycopene recovery. Seher et al. (2013)

and Biosci et al. (2015) determined that for

extraction with ultrasounds during extraction

require less time, lower temperature and smaller

amount of solvent than a conventional organic

solvent extraction. Ho et al. (2015) verified higher

lycopene yields by extracting tomato skins with

microwaves. Domingues (2009) reports that a pre-

treatment of extrusion followed by milling

increases the total extraction yield by 9.8%, for

hexane extraction.

Due to the disadvantages of toxicity and pollution

associated with organic solvents in industry,

extraction with supercritical fluids have gained a

widespread. When comparing repair extraction by

Soxhlet method with hexane and supercritical CO2

extraction, Domingues (2009) found that the mass

extraction yield was higher for extracts obtained

with supercritical CO2, but that the lycopene

concentration was lower. Several authors have

investigated supercritical extraction; however, the

process requires the installation of expensive

equipment due to high pressures (Nobre et al.,

2012).

Oil extraction

The present study focused on the feasibility of

extraction of an oleoresin, from tomato pomace, in

an oilseed processing factory. The process

implemented is optimized for rapeseed and

soybean seeds and can be divided into four key

steps:

Seed cleaning and preparation

Oil extraction (mechanical and/or

chemical)

3

Treatment of oil/hexane miscella

Treatment of the meal

A proper preparation of the seeds is crucial to have

a successful extraction. The material’s water

content should be between 10 – 13 % (w/w) in

order to prevent deterioration and allow the

highest extraction yield (Young et al., 1994). There

is a cleaning system to remove any unwanted

foreign matter or dust, usually by sieving. For

bigger seeds, there is a milling step. After there is

conditioning, rolling process and mechanical

pressing or extrusion. To ensure percolation of the

solvent in the seeds, the material needs to be

porous, spongy and permeable. The purpose of

extrusion and pressing is to increase the surface

area and decrease the bulk density. For a good

diffusion of the solvent, the consistency of the

solids should not be too dry and granular or too

compact and wet. If this diffusion is impaired, the

solvent hold-up will increase and can originate

problems in the extraction equipment (Mulder et

al., 2011).

Extraction occurs due to successive washing of the

solids with hexane and the resulting miscella is

treated in a distillation column. The meal goes

through a Desolventizer-Toaster-Dryer (DTD) and

the hexane is partly recycled.

Industrial Dryers

Water removal from solid materials is necessary

for several reasons: reducing transportation costs,

ease sample handling, storage and achieve product

specifications. The pomace exiting the tomato

processing plant contains a high moisture content

(60 - 90% w/w), that should be reduced to 8 - 10%

(w/w) in order to achieve biological stabilization

and maximum extraction yield.

Since the separation of tomato juice from the skins

and seeds is done continuously and discharges a

high solids flow rate, the mode of operation needs

to be continuous.

The drying process should have a high evaporation

rate, be adequate for granular and friable solids,

and provide a moderate agitation of the product.

Following literature review, the most suitable

industrial dryers for this purpose are the rotary

cylinder, the tubular bundle and the fluidized bed

dryer.

The rotary cylinder dryer is widely used in the

industry due to its high evaporation rates. The

equipment is a cylinder tank that rotates with a

slight slope to promote material flow by gravity.

The injection of a hot air stream promotes a direct

heat exchange with the material (Mujumdar, A.,

Osman, P., 2006).

The tubular bundle dryer is a configuration of the

rotary cylinder. It has a similar outer shell, but the

heat transfer is indirect through several interior

bundles where the heating agent circulates.

Fluid bed drying is extensively used in the

pharmaceutical industry, to reduce moisture

content of powders and granulates. The

equipment works through the flow fluidization

principle. The solids or pastes enter a chamber

with a perforated surface. Tot air is inserted

through the holes at high pressures to promote

drying.

Pomace fractions separation

The disparity in the chemical composition of the

seeds and skins constituting the pomace, suggests

distinct valorisation potentials.

The approaches to skin and seed separation can be

divided into wet or dry separation. The principle

for wet separation involves the mixing water to

promote skin fluctuation and seed sedimentation

based on the density of the components. Kaur et

al. (2005) developed a flotation-sedimentation

system that allows a separation efficiency of

69.17% for seeds and 48.29% for skins. Shao et al.

(2013) stated that by adding a second float-

sedimentation tank the separation efficiency can

reach 90%. For dry separation it is necessary to

dehydrate the pomace before. Methods for

recovering seeds and skins include sieving,

fluidized bed separators and/or cyclones, based on

the difference in particle size density. Shao et al.

(2015) state a recovery efficiency of 68.56% and a

purity of 82.20% and 86.11% for skins and seeds,

respectively.

Objective

4

The present work had an experimental component

in order to investigate the physical characteristics

of tomato pomace, the simulation of some

potentially critical aspects of the extraction in the

oilseed extraction plant and determination of

lycopene content in the resulting oleoresin.

2. Materials and methods

Sample and reagents

The pomace was generously supplied a tomato

processing company. The material was frozen for

ten months at -15oC. Fresh samples from this

year’s harvest were also analysed. The petroleum

ether for extractions and dilutions was from CARLO

ERBA Reagents.

Analytical procedures

Moisture content was determined by the drying

oven method, at 103±2oC. A sample of 5±0.01g was

weighted in a METTLER TOLEDO analytical balance

and placed in a Heraus oven until constant weight.

The drying curve was drawn by periodic weightings

of the pomace at 103±2oC through time. The

effects of sample agitation were assessed. The

drying temperature was chosen according to

literature data, indicating less than 10% lycopene

degradation at 110oC and no variation detected at

80oC (Singh et al., 2015; Zanoni et al., 1998; Zanoni

et al., 2000).

Bulk density was determined by the empiric

formula by weighting a sample in a graduated

beaker. The seeds, skins and fibres ratios were

determined by manual separation and weighting of

the resulting fractions. Particle size distribution

was obtained by sieving methods, in an Endecotts

12 sieve system.

The dry and wet pomace was subjected to

microbiological analysis to investigate the presence

of Salmonella bacteria. The tests were repeated

periodically over 5 months using a 1-2 Test kit from

Millipore.

A dry separation method was developed. An

elutriation system was built with an acrylic tube

and an air stream regulation system. The airstream

flow is necessary to calculate the fluid velocity (eq.

1) and achieve separation through difference in the

particle’s linear velocity (4). The airflow can be

estimated through Bernoulli’s Principle for fluid

dynamics (eq. 2 and 3).

𝑄𝑎𝑖𝑟 = 𝑣1 × 𝐴1 = 𝑣2 × 𝐴2 (1)

𝑃1 +1

2 𝜌𝑣1

2 + ℎ1 = 𝑃2 +1

2 𝜌𝑣2

2 + ℎ2 (2)

After some arrangements the following equation is

obtained:

𝑄 = 𝐴𝑜𝐶𝑓√2∆𝑃

𝜌 (3)

𝑃 – Pressure (bar)

𝜌 – Fluid density (kg/m3)

𝑣 – Fluid velocity (m/s)

ℎ – Elevation (m)

𝐴𝑜 – Orifice area (m2)

𝐶𝑓 – Drag coefficient

The rolling process was simulated in a Brabender

rolling mill, model PM-2000. The rotation velocity

was set at 25 rpm and the heating at 90oC. The

seed thickness was measured with a digital caliper

from POWERFIX.

The extrusion was achieved with a Brabender

equipment model D-4100. The operation

conditions were adjusted to replicate the factory

equipment.

The permeability tests were performed according

to a supplier’s method and are confidential. The

results are presented as the necessary time for a

certain amount of solvent to pass through a solids

layer.

The mass recovery yield was determined by

Soxhlet extraction according to the Portuguese

Norm NP EN ISO 659:1998, with petroleum ether,

at 103±2oC for 6 hours.

Extractions in Soxtec equipment were also

performed. The equipment was from FOSS, model

2050 SOXTEC Auto Extraction Unit. The chosen

program has the total duration of 70 minutes at

135oC.

For the determination of lycopene content in the

extract a UV-Vis method was developed. The

5

0

10

20

30

40

50

60

70

0 200 400 600

% H

2O

(w

/w)

time (min)

0

5

10

15

20

25

30

35

40

% (

w/w

)

Mesh opening (mm)

Figure 2 - Size distribution for pomace particles, obtained by sieving.

maximum wavelength, 𝜆𝑚𝑎𝑥, was obtained after

analysis of a diluted sample in a

spectrophotometer from Thermo ScientificTM

,

model MultiskanTM

GO. The value for molar

extinction coefficient was determined from a

calibration curve obtained by dissolving an extract

in petroleum ether. The lycopene concentration

was then calculated using the Lambert-Beer Law

(eq. 4).

𝐴 = 𝜀𝑏𝐶 (4)

𝐴 - Absorbance

𝜀 – Molar extinction coefficient (L.M-1.cm-1)

𝑏 – Optical path length (cm)

𝐶 – Concentration (Molar)

The meal obtained after Soxtec extraction and the

permeability tests was characterized for fibre (NP

EN 806868), protein (NP EN ISO 5983-2), moisture

(ME 20.04), residual oil (NP EN ISO 659:1998) and

ash content (NP ISO 5984). The results for the

analysed meal parameters were introduced in a

NIR equipment (FOSS) to initiate the calibration of

the method.

3. Results

The initial moisture content was determined by

equation 5. The drying curves are shown in Figure

2. By agitating the sample, the necessary time to

achieve 8 – 10 % H2O (w/w) decreased by 100 min.

%𝐻2𝑂 =𝑚 𝑖− 𝑚 𝑓

𝑚 𝑖× 100 = 59.9 ± 0.45 % (𝑤/𝑤) (5)

The average mass percentages for the ratios were

67% for the seeds, 33% for the skins and 1.5% for

fibres and others.

The results for bulk density are shown in Table 1.

Table 1 – Densities obtained for several pomace samples.

Description ρ (kg/m3)

Wet pomace 168.81 ± 3.39

Dry pomace (67% skins) 96.85 ± 0.96

Dry pomace (50% skins) 100.29 ± 1.99

Dry pomace (33% skins) 105.84 ± 1.96

Dry pomace (6% skins) 336.45 ± 2.72

The size distribution obtained for the pomace

particles is in the histogram of Figure 3. It was

verified that the seeds are retained between the

sieves with mesh opening of 1.41 and 3.36 mm.

All the results of the analysis for Salmonella

detection were negative. Please note that the

presence of other microorganisms was not

investigated.

The terminal velocities for the seeds (0.734 m/s)

and skins (1.958 m/s) of the pomace were

obtained by equation 10 after rearrangement of

equations 6, 7, 8 and 9.

𝐹𝑎 = 𝑃 − 𝐼 (6)

�⃗� = 𝑚. 𝑔 = 4

3𝜋𝑟3. 𝑔 =

𝜋𝐷3

6. 𝜌𝑔 (7)

Figure 3 - Drying curves for tomato pomace in oven at 1032oC, with (•) and without agitation (•).

6

33% skins 50% skins

68 % skins

6% skins

68% skins (powder)

Reference

0 20 40 60 80

Per

mea

bili

ty v

elo

city

(m

3 /(m

2.h

)

(% skins (w/w)

Figure 4 - Results for the permeability velocity.

𝐼 = 𝜌𝑓 𝑉 𝑔 =𝜋𝐷3

6𝜌𝑓𝑔 (8)

𝐹𝑎⃗⃗ ⃗ = 𝑓 ×

1

2𝜌𝑢2 × 𝐴𝑝 (9)

𝑢𝑚 = √4 (𝜌𝑓−𝜌)𝑔 𝐷

3 𝜌 𝑓 (10)

𝐹𝑎 – drag force (kg.m.s-2

)

𝑃 – Weight force (kg.m.s-2)

𝐼 – Buoyancy force (kg.m.s-2)

𝑚 – Particle mass (kg)

𝑔 – Acceleration force, 9.8 m2/s

𝐷, 𝑟 – Diameter and radius(m)

𝜌, 𝜌𝑓 – Fluid and particle density (kg/m3)

𝑉 – Particle volume (m3)

𝑢, 𝑢𝑚 – Linear velocity of the particle (m/s)

𝐴𝑝 – Particle superficial area (m2)

𝑓 – Drag coefficient

After conducting a series of tests with the

elutriation tube, it was verified that the skins break

into smaller particles, forming a thin powder. This

powder’s linear velocity (0.791 m/s) was calculated

using equation 10. The velocity of the air flowrate

was set between 0.64 and 1.10 m/s.

The linear velocities for skins (powder form) and

seeds are very close, thus the separation through

fluidization was not achieved. Despite this, after

the elutriation step, it was possible to separate the

seeds from skins using sieve equipment.

The mil rolling resulted in a 42% seed thickness

reduction. The extrusion allowed a compaction

comparable to the industrial process.

For the permeability test, several ratios of seeds

and skins were analysed in order to verify if the

drainage of the extractor is enough. The results for

the velocities obtained are in Figure 4. All the

samples, except one, show a higher velocity than

the internal reference. The sample that showed a

lower velocity had the same skins percentage as

the original pomace exiting the tomato processing

but was replaced for powder skins instead of the

original granulometry.

The mass recovery yield, obtained with Soxhlet

extraction for the samples with different skins ratio

are presented in Table 2.

Table 2 – Mass recovery yields obtained for pomace samples with different ratios of skins and seeds.

% skins (w/w) Mass recovery yield (gext/gpomace)

68 0.102 50 0.124 33 0.137 6 0.269

The absorbance spectrum of the extracts shows

three peaks (418, 467 and 499 nm). The peak

chosen for spectrophotometric analysis was 467

nm. The molar extinction coefficient determined

by the calibration curve for the lycopene in the

extract matrix was 1.64 x 105L.M-1.cm-1. The value

is coherent with the literature.

The lycopene concentrations in the extracts are

presented in Table 3. The results indicate that the

lycopene concentration is higher for samples with

a greater skin mass percentage. The Soxtec

extraction had considerably higher lycopene

content, probably due to the reduced heat

exposure time. The effects of different storage

conditions of dry pomace, absence or presence of

light and room temperature or 4oC are also shown

in the same table. The degradation of lycopene

due to light and heat exposure is evident.

The quality parameters for the Soxtec extraction

resulting meal were introduced in the NIR

calibration program. The calibration was obtained

for five parameters (water content, residual oil,

fibre, protein and ashes) with ten samples. After

7

calibration a new sample was introduced in the

equipment and the values obtained with the

calibration equations were compared with the

laboratory results. The relative errors for these

results are presented in Table 4.

Table 4 - Relative errors of the calibration curve obtained by NIR spectrum analysis, with ten samples.

Water content

(%)

Residual oil (%)

Fibre (%)

Protein (%)

Ashes (%)

21.13 42.30 4.97 9.24 7.17

Aiming to minimize the relative error of the

calibration curves, the values for four more

samples were introduced in the program. The

errors of the results obtained by the calibration

curve decreased substantially (Table 5).

Table 5 - Relative errors of the calibration curve obtained by NIR spectrum analysis, with fourteen samples.

Water content

(%)

Residual oil (%)

Fibre (%)

Protein (%)

Ashes (%)

10.71 6.47 4.89 4.37 3.65

4. Discussion

4.1 Dryer Selection

From the results obtained for the drying curve it is

concluded that for a more efficient and

homogeneous heat transfer, material agitation is

required. Agitation of the pomace also prevents

agglomeration. In the elutriation tests carried out,

it was verified that dry skins are very friable and

breakable, and are reduced to powder, when in

contact with high air flowrates. According to the

permeability tests it was established that the

presence of fines and small particles is highly

adverse for the extraction process, decreasing the

permeability velocity of the solvent, likely to cause

drainage problems.

The installation of the dryer must be done at the

premises the tomato processing factory. Due to

the seasonality of the campaign and subsequent

processing of the tomato, it would be beneficial to

install the dryer in the oil extraction company and

investigate the use of other agricultural wastes

with an unmatched harvest season. However,

there were no agribusiness companies in the

proximities with by-products of interest. If it is

decided to buy repairs from other companies, the

processing time is coincident so the sizing of the

dryer would be another, more expensive and

larger. In addition to these factors, the

transportation cost would be much higher due to

the weight inflated by the high water content.

Several suppliers were contacted and the received

proposals analysed. The proposal A was for a

tubular bundle dryer, the proposal B was for a

fluidized bed dryer and proposal C was for a rotary

cylinder dryer. For the selection, several factors

were considered, bearing in mind the

characteristics of the pomace analysed, and the

features of the types of dryers considered. A

weighting factor between 1 and 10 was assigned to

each criteria (Table 6) to assess the received

proposals:

1. Investment and installation cost

2. Utilities consumption

3. Electricity consumption

4. Maintenance/Cleaning

mglycopene/100goleor

Fresh pomace Soxtec

68% skins (w/w) 112.0

Fresh pomace Soxhlet

6% skins (w/w) 4.1

33% skins (w/w) 48.0

50% skins (w/w) 62.1

6 % skins (w/w) 85.2

Frozen pomace Soxhlet

6% skins (w/w) 3.7

33% skins (w/w) 24.7

50% skins (w/w) 48.9

68% skins (w/w) 59.4

68% skins (w/w), 5-month storage, 4oC

absence of light 63.0

68% skins (w/w), 5-month storage, room temperature, absence

of light

35.4

68% skins (w/w), 5-month storage, room

temperature, presence of light

20.9

Table 3 - Lycopene concentration on the resulting extracts.

8

5. Process continuity

6. Robustness

7. Process flexibility

8. Area required for instalment

9. End-product specifications and quality

10. Moderate and effective agitation

11. Evaporation rate

12. Adequate for heat sensitive products

13. Unit assembly and installation

Table 6 - Weighting factors assigned to each criteria for ranking the drying technologies under study.

Criteria Weighting

factor Proposal

A Proposal

B Proposal

C

1 9 10 7 1

2 8 1 1 10

3 6 10 1 3

4 8 6 1 10

5 10 10 2 10

6 6 8 5 10

7 7 8 1 10 8 8 6 1 6

9 7 10 7 8

10 9 10 1 4

11 8 10 1 8

12 8 10 10 10

13 5 10 5 1

Total score

99 828 321 706

Proposal A

The dryer proposed by supplier A is a tubular

bundle dryer, with indirect heat transfer. The pipes

are arranged in a star configuration supported by

an axial rotating shaft in the centre of the cylinder.

The heating agent is saturated steam. The

equipment includes a cyclone for water and dust

removal. This removal is achieved with a moderate

air stream, which suggests minimum skins

breakage. It also has fire prevention equipment,

ensuring the safety of the process. The investment

cost is the lowest of the three proposals and the

utility costs only slightly higher.

Since the heat supply is indirect and the steam and

fines removal rate is moderate, this is the most

favourable alternative for drying.

Proposal B

Proposal B is the fluidized bed type. Combustion

gases, from a burner, are injected through a

perforated surface. This dryer separates the skins

from the seeds and has the lowest evaporation

rate (as it has no capacity for drying the removed

skins). The supplier suggests total skin separation,

achieved by incorporating two cyclones. The area

required for the fluidization chamber and the two

cyclones is too high, a limiting factor at the factory.

The supplier recommends reuse of skins by

incorporation into pastes and sauces as a

thickening agent. However, this system is not

permitted by the tomato processing factory quality

and legal specifications.

Proposal C

The proposal from supplier C is a rotary cylinder

dryer. Heat transfer is direct and is achieved by

passing a flue gas stream at high counter current

temperatures.

Typical speeds for this type of dryer are around 3

m/s for co-current and 2 m/s counter current

dryers. These speeds translate into very high gas

flow rates, higher than those used in the

elutriation process. The probability of breaking the

skins and forming very small particles is very high.

This criteria is crucial, as it was verified in the

permeability tests that the formation of fines is

highly unfavourable for the process.

This dryer, despite having slightly lower operating

costs, has higher investment costs. Before the

development of this project, drying was done with

a dryer of this type. However, the risk of fire was

very high and the selling price of the dried pomace

was very low as it was intended for animal feed.

Decision

With the results obtained, concerning the

characterization of tomato pomace, and the

reproduction of the pre-treatment existing in

oilseed extraction company, the necessary

conditions for the decision of the dryer were met.

Mandatory criteria for selection are process

continuity, moderate agitation of the material so

as not to create fines but also no agglomeration,

reduced plant space, operating costs and

investment value, lycopene degradation, water

evaporation rate and the volumetric capacity

appropriate to the process.

9

From the analysis of Table 6 and data collected in

the experimental part, it was concluded that the

most appropriate proposal was from supplier A, a

tubular bundle dryer.

5. Economical analysis

To analyse the economic viability of the project

some assumptions were made:

Investment in dryer of proposal A

Investment in a cleaning system

Investment in three heat recovery systems to

increase steam output from boilers

Transportation and installation costs of

industrial equipment (dryer, cleaning system

and three heat recovery units) calculated using

literature factors (Walas et al., 2012)

Consumption of utilities are identical to those

discriminated by supplier A

Utility prices are internal values

Shipping costs from B to A are internal values

For processing operating costs were

considered internal values

The extraction process yield was the average

yield of the oilseed extraction factory

The oil degumming process was not

considered (crude oil)

Taxes - 21%

Cash flow update rate - 10%

Price of meal obtained by interpolation of the

prices of soybean and rapeseed, in relation to

the protein content

Lifetime of purchased industrial equipment is

8 years

Three scenarios were considered:

1st

scenario - the minimum price of the

oleoresin for a payback time of 3 years, was

calculated using the Solver function of

Microsoft Excel (pessimistic)

2nd scenario – the price for the oleoresin was

considered to be identical to price market of

olive oil

3rd

scenario – the market value of the

oleoresin was accounted as 10% of the selling

price of tomato seed oil

Table 7 - Economic indicators resulting from the 8 year economical analysis for three scenarios.

1st

scenario

2nd

scenario

3rd

scenario

Payback-time (years)

3 2 1

Investment Return Rate (IRR)

11% 53% 308%

Economic valuation is a very important segment in

determining the feasibility of implementing

industrial equipment. The data presented was

based on estimates and therefore do not

accurately represent reality.

From the results of the economic analysis

presented, it is concluded that the project allows

the valorisation of a by-product, with reasonable

payback-time and that it is an attractive

investment with low associated risks.

6. Conclusions

The main objective of this work was to study the

suitability of the extraction process of a by-product

of a tomato processing company, in the facilities of

a plant optimized for the extraction of oilseeds.

After extensive review of the laboratory results it

was possible to scrutinize the proposals of the

three dryer suppliers contacted. It was concluded

that the steam tube dryer (proposal A) was the

best option. As the current steam production is

limiting, the implementation of heat recovery

plants in three of the installed boilers was

considered. In order to ensure the safety and

efficiency of the process, it was considered

installation of a pre-cleaning system for the dried

pomace.

The rolling and extrusion steps allowed simulating

the pre-treatment installed at the seed processing

factory. The permeability tests with tomato

pomace (68% w/w skins) indicate sufficient

drainage in the extractor. The extractions and

subsequent mass yield and lycopene analysis

indicate that is possible to achieve a high value

product with considerable recovery yield from an

unused by-product.

The economic analysis, although many

assumptions have been considered, made possible

10

to calculate indicators of project viability. For the

three scenarios studied, payback time and internal

rate of return (IRR) values were considered

attractive for the project progress. For the

pessimistic scenario an IRR of 11% and a 3 year

payback time were obtained, for the intermediate

scenario the IRR was 53% and the payback time is

2 years and for the optimistic scenario the payback

time was in the first year and the IRR obtained was

308%.

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