DOI: 10.3303/CET2291042 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Paper Received: 10 January 2022; Revised: 11 March 2022; Accepted: 13 May 2022 
Please cite this article as: Herrera T., Parejo V., Gonzalez-Delgado A., 2022, Chemical and Process Inherent Safety Evaluation of Avocado Oil 
Production (laurus Persea L) in North Colombia, Chemical Engineering Transactions, 91, 247-252  DOI:10.3303/CET2291042 
  

 CHEMICAL ENGINEERING TRANSACTIONS  
 

VOL. 91, 2022 

A publication of 

 

The Italian Association 
of Chemical Engineering 
Online at www.cetjournal.it 

Guest Editors: Valerio Cozzani, Bruno Fabiano, Genserik Reniers 

Copyright © 2022, AIDIC Servizi S.r.l. 

ISBN 978-88-95608-89-1; ISSN 2283-9216 

Chemical and Process Inherent Safety Evaluation of Avocado 

Oil Production (Laurus Persea L) in North Colombia 

Tamy Herrera, Vianny Parejo, Ángel González-Delgado* 

Nanomaterials and Computer-Aided Process Engineering Research Group (NIPAC), Chemical Engineering Department, 

Faculty of Engineering, University of Cartagena, Cartagena 130015, Colombia  

agonzalezd1@unicartagena.edu.co   

The largest production of Creole avocado in Colombia is found in the north zone, mainly in the Montes de María 

region, but due to weather conditions, the presence of pests, or transportation routes, a high percentage of the 

production is damaged. As a way to take advantage of the fruit not suitable for exportation, it is possible to 

obtain different products such as avocado oil, since this fruit contains around 30 % of crude oil. Accordingly, it 

is necessary to evaluate the oil production process from a safety point of view. The Inherent safety index, or ISI, 

allows a global measurement of safety in the early design stages of chemical processes. To carry out the 

process safety analysis, the risks associated with the use of chemical substances were first identified, 

determining their index of toxicity, corrosion, flammability, explosiveness, and the chemical reactions if 

necessary. Second, the risks of the process were evaluated, taking into account the equipment involved, 

manufacturing material, temperatures, and pressures that are handled. An Inherent safety index of 17 points 

was obtained, which indicates that the process is safe despite working with substances such as hexane and 

sodium hypochlorite and using equipment such as ovens and distillation columns. 

1. Introduction 

Industrial development and population growth have led to the need to seek more sustainable energy sources 

such as biomass (Ahmad et al., 2021).  Colombia produces more than 500,000 tons of avocado, of diverse 

varieties, which places the country in the top third positions of worldwide production (Sánchez, 2021). The 

Bolivar department cultivates avocados of the Creole-Antillean variety mainly in the Montes de Maria region due 

to its climatic conditions (Ministerio de Agricultura, 2018). In recent years, avocado plants deterioration has been 

observed for fungi appearance in cultivation area; besides, harvesting transportation has been affected for roads 

poor condition. This fruit is sensitive to climatic conditions, suffering enzymatic darkening in pulp, whereby, 

industrially pulp is used to obtain cosmetic purposes oil, for example as present in figure 1 (Burbano, 2019). 

The use of these types of biomass becomes interesting to obtain value-added products through biorefinery 

schemes, mitigating the adverse environmental effects caused by the disposing methods (Poveda-Giraldo et 

al., 2021). 

Some of the techniques used for oil extraction involve the presence of solvents, enzymes, the application of 

centrifugation or pressure. The solvents used correspond to hexane, ether, chloroform, acetonitrile, benzene, 

and ethanol. Solvent extraction increases the yield by carrying out simultaneous extractions in parallel. 

Generally, the process is carried out at the boiling point of the solvent for a long time. (Corzzini et al., 2017). 

Likewise, extraction with solvents is ideal for the production of oils for cosmetic use (Serpa et al., 2014). In this 

study, the assembly of an avocado processing plant (Laurus Persea L) for the production of oil will be evaluated 

from the point of view of process safety, obtaining a product with added value. For this, the chemical reactions 

of the process must be taken into account, the reagents used to identify characteristics of the substances such 

as flammability, corrosivity, explosivity, and toxicity. In addition, an inventory of equipment must be carried out 

and the construction material of the same must be considered. These characteristics of the process are identified 

to assign a score to each one of them, allowing to determine the inherent safety of the avocado oil production 

process from the pulp of this fruit. 

 

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Figure 1: Potential value-added products obtainable from Creole-Antillean avocado. 

2. Materials and methods  

The avocado oil plant was modeled based on scientific literature data collection, the information was used to 

simulate a large-scale solvent extraction process; stages, streams, and operating conditions are described 

below. 

2.1 Process description 

For this process, the solvent oil extraction method is applied using hexane. As shown in figure 2, first of all, raw 

material is washed in a sodium hypochlorite solution coming from stream 2; the impurities and contaminants 

present in the fruit are removed from the process in this washing stage. Once the avocado is clean, the peel is 

pulled out and carried to the washing stage; in the washing step, the remaining pulp is recovered from the peel 

(stream 13). In the next stage, the seed is separated from the pulp; the pulp (stream 7), is conducted to the 

homogenization stage and the seed is washed to obtain a clean seed and a pulp-water mixture (stream 10).  

 

 

Figure 2: Process flow diagram of Creole-Antillean avocado oil extraction. 

The pulp obtained from the extraction stage is mixed with the remaining pulp from the washing stage and the 

mixture is homogenized, then, the pulp is led to the drying stage where excess water and moisture are removed 

before extraction. This operation occurs at 1 bar of pressure and 70 °C in order not to degrade the pulp (Ariza 

Ortega et al., 2011). In the extraction stage, hexane was used to obtain oil from the pulp; the mixture is 

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centrifuged to remove the suspended solids, which leaves the process as waste. The oil-solvent mixture goes 

to a flash distillation where the oil is separated as the desired product of hexane, which is condensed, and a 

fraction is recirculated to the extraction stage. The crude oil is cooled down to a storage temperature of 25 °C 

to preserve its properties (Robayo, 2017). 

2.2 Inherent safety index (ISI) 

Calculations for Inherent Safety Index (ISI) are based on the riskiest process performance, considering the worst 

substances chemical interaction, structure, and process variables, due to intrinsic safety is impacted by process 

equipment and the properties of the chemical substances implicated in the process. This indicator evaluates the 

potential inherent hazard related to the industrial chemical process at a conceptual design phase (Meramo et 

al., 2020). Therefore, the sum of the Chemical Inherent Safety Index (ICI) and the Process Inherent Safety Index 

(IPI) represents the Total Inherent Safety Index (ITI) as shown in Eq. (1) (Moreno et al., 2021). 

 

𝑰𝑻𝑰 = 𝑰𝑪𝑰 + 𝑰𝑷𝑰 (1) 

 
𝑰𝑪𝑰 =  𝑰𝑹𝑴,𝒎𝒂𝒙 + 𝑰𝑹𝑺,𝒎𝒂𝒙 + 𝑰𝑵𝑻,𝒎𝒂𝒙 + (𝑰𝑭𝑳 + 𝑰𝑬𝑿 + 𝑰𝑻𝑶𝑿) 𝒎𝒂𝒙 + 𝑰𝑪𝑶𝑹,𝒎𝒂𝒙 

                           

(2) 

𝑰𝒑𝒊 = 𝑰𝒊 + 𝑰𝑻,𝒎𝒂𝒙 + 𝑰𝑷,𝒎𝒂𝒙 + 𝑰𝑬𝑸,𝒎𝒂𝒙 + 𝑰𝑺𝑻,𝒎𝒂𝒙  (3) 

The Chemical Inherent Safety Index contains chemical factors listed in Eq. (2), determined separately for each 

substance in the process. The variables included are Heat main reaction (IRM,max), Heat of side reaction (IRS,max), 

Chemical interaction (INT, max), Flammability (IFL,max), Explosiveness (IEX,max), Toxic exposure (ITOX,max), 

Corrosiveness (ICOR,max). (Meramo-Hurtado et al., 2021). The Process Inherent Safety Index includes 

parameters of the process itself, such as Inventory (Ii), Process temperature (IT, max), Process pressure (IP,max), 

Equipment safety (IEQ,max), Safe process structure (IST,max), Eq. (3).  Table 1 shows the safety parameters score.  

Table 1: Safety parameters score. 

Chemical Inherent Safety Index 

Symbols IRM,max IRS,max INT, max IFL,max IEX,max ITOX,max ICOR,max 

Score (0-4) (0-4) (0-4) (0-4) (0-4) (0-6) (0-2) 

Process Inherent Safety Index 

Symbols Ii IT,max IP,max IEQ,max 

(0-4) OSBL 

IEQ,max IST,max 

Score (0-5) (0-4) (0-4) (0-3) ISBL (0-5) 

The flammability parameter is measured by boiling point and flashpoint, the minimum temperature for the 

substance solvent to ignite or burn. (Ahmad et al., 2020). Explosiveness reports the tendency of a gas to form 

an explosive mixture with air, which is described by lower explosion limits (LEL). Toxic exposure is classified as 

health hazards determined in terms of Threshold Limit Value (TLV) in ppm units, scaled in Permissible Exposure 

Limits issued by the Occupational Safety and Health Administration in the United States (OSHA, 2019). 

Corrosiveness indicator is defined by construction material, if carbon steel is plenty a cero score is assigned. 

Process Inherent Safety Index is measured regarding process operation and equipment. For the inventory sub-

index, it is necessary to quantify material to be stored using mass flows streams. The temperature scale was 

selected on basis of material strength and threat to humans. Pressure parameters are indicated to fill strength 

vessel requirements. Furthermore, Equipment safety aims to prevent the possibility that a piece of equipment 

is unsafe. The process plan area is separated into onsite and offsite areas; the onsite area refers to the battery 

limits area (ISBL) for substantial equipment in a small section, and offsite areas are concerned to outside battery 

limits area (OSBL), which refers to a large inventory scattered in a space location (Heikkilä, 1999). 

3. Results and discussion  

3.1 Chemical Inherent Safety Index (Ich) 

Sub-indexes IRM,max and IRS,max represents the chemical reaction indicator for main and side reactions. In crude 

avocado oil extraction, no reaction took place, and therefore, these indicators have a 0 score just as the INT, max 

that considers the unwanted reactions from process substances with materials in the plant area and n-Hexane 

low reactivity. Flammability, explosiveness, and toxicity are parameters considered to identify hazardous 

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material, for avocado oil obtention using a solvent. The component with the greatest risks for the process was 

hexane employed in the extraction stage, among other substances within the process shown to be secure due 

to their non-flammability, non-toxicity, and non-explosiveness nature (Zuorro et al., 2021). 

Table 2:  n-Hexane hazardous indicators. 

Components Flash point Boiling point Explosively TLV Storage 

Units ° C ° C % ppm Material 

Hexane -23 68.5 7.7 50 steel, aluminium 

 

Table 2 shows information from the safety data sheet of the hexane. In the flammability parameter, the boiling 

point is a measure of the risk involved (Heikkilä, 1999); hexane was classified as very flammable with a flash 

point lower than zero. Explosiveness denotes the inclination of components to form an explosive mixture in air, 

related to upper and lower explosion limits, classifying hexane as not much explosive among 0-20 % values. 

Moreover, toxicity indicator is applied in an industrial context in order to protect employees at work. To close the 

chemical index, corrosiveness was defined regarding the selected material for equipment construction; 

considering that mild steel corrosion by fatty acids is negligible at ambient temperature (Chong, 2004), no special 

material is required for process equipment. 

3.2 Process Inherent Safety Index (Ips)  

Crude avocado oil plant processing capacity was estimated at 10,604.70 t/y of avocado to produce 1,000.66 t/y 

of crude avocado oil. The inventory sub-index is the total inventories of all process vessels, from inventory is 

calculated the total quantity of material to be stored, as shown in table 3. 

Table 3:  Inventory sub-index calculation. 

Equipment  Flow (t/y) Inventory (t) 

Avocado wash 32,259.00 3.68 

Peel separation 11,967.36 1.37 

Pulp separation 10,018.42 1.14 

Seed washing 2,953.33 0.34 

Peel washing 6,148.95 0.70 

Water separation 6,852.40 0.78 

homogenization 8,006.02 0.91 

Drying 8,006.02 0.91 

Oil extraction 5,383.62 0.61 

Oil centrifugation 5,383.62 0.61 

Distillation hexane 4,649.57 0.53 

condensation hexane 3,539.43 0.40 

Oil cooling 1,000.67 0.11 

Total  12.12 

 

 

Figure 3: Inherent Safety Index for Creole-Antillean avocado oil extraction. 

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The temperature and pressure sub-index were decided according to the process operations conditions; the 

maximum temperature predicted was 70 °C at the dryer and distillation stage. Plant pressure operation is 1 bar 

for most stages; therefore, pressure conditions do not represent any risk. The equipment safety index, was 

considered ISBL area due to a distillation and drying stage that requires an oven; therefore, the assigned score 

is the maximum equivalent to 4. For the process secure structure sub-index, the process was classified as 

probably unsafe (Guillen, 2016), equal to 3. Inherent safety analysis results developed for avocado oil extraction 

are present in figure 3 for each safety index. 

3.3 Total Inherent Safety Index (ITI) 

Results revealed that process is safe under the evaluated parameters, which is below the score recommending 

for a safe or neutral process corresponding to a score of 24 (Meramo et al., 2019). Table 5 shows the score for 

chemical and process sub-index.  

Table 5: Inherent Safety Index for Creole-Antillean avocado oil extraction. 

Index Score 

ICH 8 

IPS 9 

 

Total Inherent Safety Index (ITI) of 17 for the crude avocado oil plant is higher than that reported by González et 

al. (2021) to evaluate the crude palm oil production under the inherent safety parameters, obtaining a score of 

11, showing a safe process with the highest risk in the process equipment safety sub-index due to a boiler and 

dryer implementation (González et al., 2021). Both processes are considered as safe, coinciding in process 

equipment safety sub-index with the maximum score; however, they diverge in the total safety index, the above 

is due to the particularity of each process, the extraction method used and solvent application in the extraction 

of crude oil from avocado.  The process safety is necessary to support decision-making and prevent the 

degradation systems (Santos et al., 2019). Safety assessment is a valuable approach for hazard control and 

decreases its magnitude, which can be incorporated into every design and operation stage; however, 

employment inherent safety at process selection and conceptual design yields the greatest outcomes, achieving 

essential performance integrating environment, health, and safety (Khan and Amyotte, 2004). 

4. Conclusions 

The inherent safety analysis of crude avocado oil large-scale extraction using hexane was performed in this 

work. Results indicate that for a 10,604 t/y processing capacity plant, the process is inherently safe achieving a 

total inherent safety index score of 17, outcome below the set point for a neutral or safe process. Assessment 

displays an un-balanced rating for chemical and process safety inherent indexes. Operational conditions and 

thermodynamics of the reactions do not represent major concerns for the inherent safety of this process, 70 °C 

and 1 bar of pressure, do not represent any danger. However, flammability and equipment safety are risk areas 

in this process. It is important to consider that process may be inherently safe regarding one criteria, but 

unreliable from a different point of view.  In the chemical sub-index, a proper selection of construction materials 

can prevent safety problems caused by the corrosive properties of substances and process streams. Otherwise, 

the safe process structure sub-index relates process security from an engineering perspective, reporting how 

well unit operations perform together and how they must be commanded and connected; besides, quantifying 

inventory is imperative, because as a plant becomes larger, hazard potential is extensive. For future works, 

studies can contemplate applying sustainability analysis considering the economic, and exergetic variables used 

to assess this process design from different criteria. 

Acknowledgments 

The authors would like to acknowledge University of Cartagena for providing equipment and software to 

conclude this work. 

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