Biosynthesis and Processing of Fatty Acids

### **Chapter 1**

Oleochemical Processing Technology: From Process Engineering and Intensification Techniques to Property Models for the Exploitation of Residual Marine Oils

*Alicia Román-Martínez*

#### **Abstract**

A review of the efforts done in process engineering aspects, such as process optimization and process intensification of residual oils processing, are described and discussed. It should be emphasized that the important characteristics of marine oils be determined for a good process design practice, especially, the quality attributes of the residual oil as a raw material. Finally, some property prediction models that have been proposed are indicated. All these aspects: 1) novel process engineering tools, 2) quality characterization, and 3) property models, are important for sustainable products and processes implementation in a circular economy.

**Keywords:** lipid processing, lipid characterization, lipid property models, marine oils, marine oil processing

#### **1. Introduction**

Lipids are an indispensable part of the diet and participate in numerous important biological functions. Products obtained from lipid sources (e.g., animal, vegetable fats, and oils) have gained relevance in the last two decades as the need for healthier food products or the growing interest in biofuels, among others, have increased. Consequently, the processing of fats and oils has been of vital importance throughout the history of humanity [1]; lipids have been used since time immemorial, mainly for food purposes, although there are other recent applications, such as paints, lubricants, personal care products, and (bio)fuels, as well as in animal feed [2]. The increase in the variety of lipid products and population growth have caused the annual demand for fats and oils to practically double since the end of the 1990s worldwide. The total production volume for the 12 most important oils was around 90.5 million metric tons in the year 2000, while it is currently estimated at 207.5 million tons per year [3].

On the other hand, it is known that food production systems in general represent around 20–30% of the consumption of natural resources worldwide [4]. Therefore, it has become essential to consider a change toward sustainable systems at all stages of the design and implementation of processes, which implies that they have the capacity to meet the present needs of society without compromising those of future generations. As in most human activities, in the oleochemical industry, there is a continuous effort to reduce overall production costs and, more recently, to mitigate environmental impact, meet consumer needs and promote social progress [5].

In order to address these challenges, the concept of circular economy (CE) was developed to transform productive activities from a linear perspective to a circular one, increasing efficiency in the use of resources, as shown in **Figure 1** [6, 7]. Optimal use of available resources prolongs their functionality and value, promotes production patterns with cycle closure, and thus reduces waste generation [8]. This implies, among other activities, the recycling and reuse of biomass sources, and organic waste to generate various products and materials, including food, chemicals, biopolymers, fuels, and bioenergy [9, 10].

In this context, numerous proposals have been made to exploit oil/lipid-based feedstocks that could lead to waste utilization and valuable products [11–13]. Among these, waste from the fishing industry has attracted great interest as it is a source of minerals, proteins, and fats with high potential for use [14]. About 30–40% of the fish is consumed fresh, while the rest is processed for marketing and other purposes [15]. However, not all parts of the fish are consumed, as substantial parts (e.g., fish oil) are often wasted. The processing of these marine oils, in addition to offering the possibility of obtaining biofuels, can be used to extract and refine commercial by-products of high nutraceutical value, such as tocopherols, sterols, and omega-3 (ω-3) fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) [16].

These polyunsaturated fatty acids (PUFAs) from the omega-3 family have received particular attention due to their unique health benefits. Epidemiological studies conducted in the 1970s indicated a remarkably low incidence of death from ischemic

#### **Figure 1.**

*General diagram of the life cycle of products with a circular economy approach. Adapted from [6].*

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*

heart disease in Eskimos from Greenland, as well as in Japanese and Turkish coastal populations with diets rich in fish constituents [17, 18]. Since then, numerous biochemical and biomedical investigations have been published in relation to the effects of these fatty acids, whose consumption is critical for physical and mental health, and playing an important role in infant brain and eye development [19, 20].

To obtain the benefits of this family of lipids, the World Health Organization (WHO) and the North Atlantic Treaty Organization (NATO) recommend a daily intake of 200 to 500 milligrams of EPA and DHA [21]. According to the UK Scientific Advisory Committee on Nutrition Guidelines (2004), and the Dietary Guidelines Advisory Committee Report (2005) published by the Department of Health and Human Services of the United States, it is recommended to consume at least two servings of fish in the diet per week [22].

However, these recommendations are hardly met. In 2010, the global mean intake of ω-3 fats from marine sources was 163 mg/day, with huge regional variations; only in 45 of the 187 countries, the average consumption was greater than 250mg/day, while in 100 countries there is a very low consumption (<100 mg/day), generally in regions of Africa, Asia, and Latin America, representing the 66.8% of the world adult population [23].

This situation has led to the rapid growth of the ω-3 supplement industry from marine oils. At the beginning of the last decade, only about 5% of the world's fish oil production was destined for the extraction of its ω-3 content for use as ingredients and dietary supplements, while the remaining fraction was discarded or used for fish farming or aquaculture (food for raising fish) [19]. Currently, the consumption of marine oils is expanding due to the recognition and dissemination of their beneficial properties, and this demand is expected to continue growing, with the world market for ω-3 reaching around 6955 million dollars for the year 2022 [24]. Therefore, the recovery and transfer of these important nutrients from the sea to the human food chain, within the circular economy approach, is a relevant opportunity to promote economic growth, environmental protection, and human health in general.

In addition to the increase in demand, progress in the investigation of methodologies for the extraction, purification, and stabilization of ω-3 fish oil has made significant progress in recent decades, although its application has not been widely extended on a large scale in the industry due to the challenge it represents. Marine oils are complex mixtures of fatty acids with variable chain lengths and degrees of unsaturation, which makes their separation difficult [25]; in addition to being highly susceptible to deterioration processes, such as thermal oxidation and enzymatic hydrolysis [26].

Additionally, unlike the chemical industry, the development of the oleochemical industry has not had such rapid progress in terms of modeling thermo-physical properties and development of adequate computational tools for the design, analysis, and optimization of processes related to lipids, coupled with the lack of integration of sustainable aspects [27–29]. Marine oil processing involves a variety of stages, from the extraction and recovery of crude oil to the refinement and modification of the final product. Typical unit operations include fluid transport, heat transfer, and separation processes, such as adsorption, phase separation, crystallization, filtration, chemical synthesis (interesterification, hydrogenation), and vacuum steam distillation, among others [25, 30].

Within this context, the decision-making set when designing a plant, also called "process synthesis," must balance the criteria of sustainability and incorporate the circular economy within the design, for which different tools and technologies have been

developed. Among them, process intensification (PI) may be a promising engineering approach. PI is considered as any novel equipment, processing technique, or method that, compared to conventional ones, offers a substantial improvement in the efficiency and/or performance of manufacturing (bio)chemical products [31]. Another complementary definition suggests an optimization of the basic functional principles of chemical processes (momentum, heat, and mass transfer) in the design of operations [32].

A wide range of applications and developments in the oleochemical industry can be considered intensified, as shown in **Table 1**. For example, nano-neutralization seeks to integrate degumming and neutralization operations to reduce the number and size of equipment, as well as the dosage of necessary reagents and the generation of waste [34]. Companies, such as Alfa Laval® or Unilever®, have developed strategies to improve the configuration of the process and the operating parameters in order to optimize the removal of impurities depending on the nature and quality of the oil [33]. Microwave irradiation has been used to improve the efficiency of biodiesel production, reducing reaction time with energy savings of up to 44% [35]. Similarly, ultrasound-assisted transesterification of various vegetable oils has proven to be effective by increasing the contact surface between the alcohol/oil phases, improving mass transfer and reducing the amount of catalyst needed for biodiesel production [36, 54], as well as ethyl esters of fish oil [37].


#### **Table 1.**

*Some process intensification (PI) options with reported applications in the oleochemical industry.*

#### *Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*

Other strategies include oil extraction or fatty acid separation using supercritical fluids [40], membrane technology for impurity filtration [38], or PUFA concentrate [39, 55], in addition to enzymatic alternatives for different reactions [51, 52].

Evaluating different process alternatives (conventional or intensified) from a sustainable perspective normally requires multi-objective or multi-criteria decisionmaking that must often consider antagonistic criteria, that is, when deciding to prefer one, the other criteria are affected; consequently, you are forced to make more informed and, therefore, better decisions. In these problems, there is not usually a single optimal solution and it is necessary to use a decision-making methodology to be able to differentiate the alternatives and prioritize the possible solutions.

To achieve this goal, the life cycle analysis (LCA) can be a very helpful tool, since it involves metrics that characterize the environmental impact of a product or process in all its stages, from the extraction of the raw material to the final disposal of waste [56], which obviously allows integrating the concept of circular economy within the process design [57]. There are several studies that demonstrate the potential application of LCA in oleochemical systems [58]. Additionally, the use of mathematical optimization methodologies allows evaluating these multi-criteria indicators in a robust way, as well as implementing of this set of strategies in software or process simulators [59, 60] in order to speed up the decision-making process.

**Table 2** presents a synthesis of different studies carried out on the design of processes involving lipids, and the tools or approaches addressed in each one. It is possible to observe that there is rarely a comprehensive vision of the strategies or indicators that would allow achieving an optimal sustainable process (e.g., there are few studies that address the evaluation of social metrics, a pillar of sustainability as important as the economic or the environmental). Therefore, the proposal of systematic methodologies that involve the mathematical evaluation of alternatives through a balance of sustainable indicators is vital for the design of processes in the context of the circular economy. The integration of these approaches together with social aspects, such as risk analysis and the opportunity to mitigate the nutritional deficiencies of vulnerable communities (by valorizing the sources of ω-3), complement a promising strategy that would allow the generation and evaluation of robust alternatives of processing aimed at the development of a more sustainable industry.

#### **2. Marine oil processing**

The processing of plant seeds or animal tissues into edible oils can be divided into four sets of operations: extraction, refining, conversion or modification, and stabilization [77, 78]. Oil extraction consists of pressing the material or matrix to separate the crude oil from the protein-rich solids or moderately pressing it with solvent, usually hexane. The defatted solids are known as cake or flour. The oil obtained is considered "crude" because it contains undesirable components, such as pigments, phospholipids, free fatty acids, and unpleasant flavors and odors, so it must be refined to remove these contaminants, and thus obtain a high-quality edible oil. Refined oils consist mainly of triacylglycerides (>98%) that can be subsequently modified through processes, such as hydrogenation, winterization, fractional crystallization, or interesterification, whose objective is to obtain properties different from the original oil, such as the conversion of liquid oil into semi-solid fats or the fatty acid concentrate of interest (e.g., ω-3). The stabilization of the final product to suit the needs of the consumer depends on the use that it will have. Plasticizing and tempering are



*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*


#### **Table 2.**

*Examples of different approaches and tools used in lipid process design.* operations designed to stabilize mixtures used in margarines and shortenings, while nutraceutical oils used as supplements usually undergo encapsulation or microencapsulation processes to prevent deterioration and facilitate their consumption or incorporation into other food products [79].

#### **2.1 Extraction methods**

The method chosen for oil extraction depends on the nature of the raw material, as well as the capacity of the industrial plant [80]. Particularly, for fish oil, it is obtained in most cases through the "wet-rendering" process, which consists of heating or "cooking" fresh fish with steam to break the cellular structure, and then pressing to separate the particles, liquid, and solid fractions. The solid fraction is dried to produce fishmeal.

The liquid fraction contains water, oil, and minor amounts of suspended solid material. This liquid is processed using centrifuges and decanters to remove solids and separate the water from the oil, which is stored for later use as crude oil. The water fraction is evaporated and recirculated to the solid fraction before drying [81].

Other traditional methods for its extraction include enzymatic hydrolysis, autolysis, dry rendering, solvent (hexane) extraction, and more recently innovative and ecologically friendly methods, such as supercritical fluid extraction, enzyme extraction, and extraction using ultrasound or microwaves have been used [40].

#### *2.1.1 Storage and preservation of crude oil*

It can be considered that the processing of oil starts from the storage tanks since the quality and performance are affected by the conditions in which it is stored. In particular, it is desired to avoid increases in free fatty acids, oxidation products, color changes, and contamination by insoluble impurities.

In general, tanks should store oil at room temperature (<25°C), or cooler when practical and possible. It is recommended to use containers made of stainless steel that presents the least possibility of iron contamination, for example, coated food-grade stainless steel (316). It is critical to have completely sealed tanks, as well as to fill the upper space with nitrogen to displace the air and avoid its contact with the oil since PUFAs in particular are prone to oxidation phenomena, as will be described later [26, 82].

#### **2.2 Oil refining**

Refining generally refers to the removal of non-triacylglycerol fatty materials, as well as pretreatment and deacidification or neutralization operations. Consumers typically want mild or neutral-flavored, light-colored, and oxidatively stable oils, so the goal is to remove impurities that may cause the product to have an off-color or offflavor or cause harmful metabolic effects for human consumption.

Edible oils can be refined through chemical or physical processes. Each method has its own specific advantages, and the use of one or the other depends on quite a bit on the quality and type of oil involved. In chemical or alkaline refining, caustic soda is used to neutralize the free fatty acids in the oil, while in physical refining this stage is skipped, removing these acids (to a lesser extent) by single-stage distillation during the process of deodorization. In general, when the acidity of the oil exceeds approximately 2%, chemical refining is carried out, while for lower values, physical refining is


#### **Table 3.**

*Industrial oil refining methods. Adapted from [33, 80, 83].*

carried out, provided that the quality of the oil allows it [83]. **Table 3** presents the main characteristics, advantages, and disadvantages of these refining approaches.

Regardless of the approach, refining is a set of operations designed in such a way as to minimize the loss of "neutral" oil and maximize the availability of beneficial components. The traditional process [33] includes the stages of degumming, neutralization, bleaching, deodorization, and in some cases, winterization (although the latter is considered a PUFA concentrate method). Each stage is important to remove the different impurities [84].

Evolution in the ω-3 fatty acid market has led to the development of new processes for treating marine oils, designed to preserve these acids, while reducing impurities. In some cases, these processes were initially expensive, but due to the evolution of this market, they are now considered conventional processes [16]. The processing steps and the compounds removed by them can be summarized in **Table 4**.

#### **2.3 PUFA modification and concentrate**

Oil modification processes involve a substantial change in their physical behavior and structural properties, unlike the previously discussed refining processes where their effect is aimed at removing impurities and improving organoleptic properties, as well as nutritional value [1]. Chemical modifications offer the possibility of changing the properties of fats and oils within wide ranges, making them suitable for many uses.

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*


#### **Table 4.**

*Stages of oil processing and the main impurities removed in each one [16].*

Two main modification technologies are generally considered in the edible oil industry:

	- a. Interesterification: General term for reactions between an ester and fatty acid, alcohol, or other esters, although it can only describe ester-ester exchanges or randomization of oils and fats by alkaline or enzymatic catalysis.
	- b. Transesterification: Term used for ester-ester exchanges, including acidolysis and alcoholysis. It is mostly used to describe reactions of oils with methanol or ethanol for the production of biodiesel or ethyl esters.


**Table 5.**

*Techniques for the concentration and purification of omega-3 fatty acids. Adapted from [16, 86].*

Once their properties have been modified, there are additional steps that can be used to convert refined marine oils into concentrates and relatively purified esters or fatty acids into ω-3 fractions (**Table 5**).

Many of these processes described above can be adapted, combined, or in some cases improved through the use of enzymes [25, 52]. The use of simple processes based on green chemistry, low pressures, and methods that avoid toxic solvents and high temperatures have been positioned to replace conventional methods for the extraction, purification, and stabilization of marine oils rich in ω-3 fatty acids [19].

#### **3. Analysis of oils and quality parameters**

Regardless of where they come from, oils and fats are similar in terms of the effects of the aforementioned impurities on processing and final product quality. Therefore, it is necessary to determine certain key analytical values to be able to modify or establish the process conditions in order to obtain a product of satisfactory quality [1]. Each analysis provides specific information to the manufacturer, as well as to future consumers.

#### **3.1 Analytical characterization**

Tests that are important to consider in determining the quality and handling of crude fish oil (or any oil) are as follows:

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*


#### **3.2 Composition of marine oils**

Particularly for fish oils, the constitution and proportion of its lipid components depend on the extraction process, the species, and the geographical and environmental conditions; hence, the emphasis on carrying out an adequate characterization that allows obtaining information about the composition of fatty acids and their physicochemical properties, which can give an idea of the quality of the oil and its nutritional value, important considerations for a subsequent design of oil processing according to the desired product.

For this type of oil, triacylglycerides occupy the largest proportion (90%); the moisture content and the percentage of free fatty acids vary according to the extraction treatment and storage conditions, these being around 0.5–1% and 2–5%, respectively [81]. The amount of phospholipids can vary from 1 to 1.5%, and in terms of the content of the unsaponifiable fraction (sterols, tocopherols, pigments, alcohols, and hydrocarbons), it is normally less than 2%, although it can constitute up to 8% of the oil under certain seasonal and feeding conditions [93].

The fatty acid profile allows a chromatogram to be obtained from which the type and content of fatty acids belonging to saturated, monounsaturated fatty acids or PUFAs is determined. The profile of fish oils is known to be complex, varying by marine species. There are fatty acids that occur in trace amounts and some are generally common to all species. For example, high contents of PUFAs have been found in tuna oil (35% w/w) [94], in cod liver (18% w/w), and anchovies (16.5% w/w) [95].


#### **Table 6.**

*Ranges of fatty acid profiles of some fish oils determined by gas-liquid chromatography (expressed as percentages of total fatty acids). ND = not detected, defined as <0.05%. NA = not available; ω3 = omega-3 series, ω6 = omega-6 series, ω7 = omega-7 series, ω9 = omega-9 series [95].*

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*

While the monounsaturated fatty acids, oleic acid (C18:1) is the most abundant, and as for the saturated ones, large amounts of myristic acid (C14:0) and palmitic acid (C16:0) can be found in almost all the species analyzed [94].

It is important to mention that the positional distribution of the different types of fatty acids in the glycerol molecule of triacylglycerides, especially, the ω-3 PUFAs, has a strong influence on digestion and absorption in the human body, as well as on its oxidative stability [96]. In marine oils, DHA is generally found in the sn-2 position, while EPA can be found in any position of the glycerol molecule [97]. **Table 6** below presents a comparison of the fatty acid profile of oils from different fish species reported by the CODEX Alimentarius Commission of the World Health Organization.

Regarding specific tuna oils, various authors in different locations have reported relatively similar fatty acid profiles. The percentages of PUFAs vary from 28 to 44%, with DHA being the most abundant, followed by EPA and, to a much lesser extent, DPA [94, 95, 98]. Oleic acid represents the highest percentage of monounsaturated, and of the saturated, myristic acid stands out.

#### **3.3 Lipid deterioration**

Fats and oils can undergo different deterioration processes that, in addition to reducing the nutritional value of the food, produce volatile compounds that impart unpleasant odors and flavors. The degree of deterioration depends on the type of fat or oil, the handling given to it [99], and the storage conditions, being the most affected oils of marine origin, followed by vegetable oils and finally animal fats, due to the fact that the first they contain a greater amount of PUFAs prone to the deterioration [1]. Some examples are:


Fats have a certain resistance to oxidation processes depending on the initial natural content of antioxidant and/or prooxidant substances. Oxidation is slow until this resistance is overcome, at which point it accelerates rapidly. To delay these processes, it is possible to add natural or synthetic antioxidants to the oil, which help reduce oxidation through different mechanisms: inactivation of pro-oxidant metals through chelation, elimination of free radicals by phenolic compounds (tocopherols, BHT, and BHA), or removal of simple O2 species by compounds, such as astaxanthin [101].

#### **3.4 Quality requirements**

The quality of oil can be defined based on parameters established by various international organizations or regulations, as well as by the use that will be given to the oil. In the case of edible oils destined for concentrated supplements of ω-3, it is suggested to take into account the parameters described below in **Table 7**, in order to ensure a safe product for the consumer, as well as to establish restrictions and conditions that may be included in the time of process design.

#### **4. Models of thermodynamic and physicochemical properties of lipids**

As has already been described, vegetable and animal oils are mixtures of lipids, mainly fatty acids in the form of triacylglycerides, phospholipids, and unsaponifiable matter, among others. Therefore, the composition and proportion of these compounds vary significantly according to the source of origin, having a direct impact on the


**Table 7.**

*Guide to quality parameters and potential areas of problems or disadvantages. Adapted from [81, 95, 102].*

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*


#### **Table 8.**

*Main characteristics of marine oils in general [93].*

physicochemical properties and the appropriate design of the processing applied to the oil to obtain products suitable for use and consumption by humans [81].

Lipids are not commonly tabulated in property databases, and their polyfunctional structure requires a careful model analysis [103]. Properties, such as melting and boiling temperature, density, viscosity, and liquid-vapor equilibrium data, have been experimentally reported for different sources of oils and fats, the most studied being those of vegetable origin. However, the wide range of lipid species and the enormous number of different configurations that fatty acids can have in the triacylglyceride molecule make it difficult to fully characterize all properties of a given species. It is possible to take some general characteristics (**Table 8**) for a preliminary process design.

As not, all the properties of the lipids of interest have been determined in the literature and due to the difficulty, cost and time consumption involved in carrying out complete experimental studies, it is possible to resort to property prediction methods using mathematical models. In particular, group contribution (GC) methods have been widely used to complement the information available for process design [104].

#### **4.1 Group contribution methods**

The use of GC methods is based on the structural information of the molecule to predict specific properties; each substance is considered to be formed by the union of suitably defined structural groups, and each one of them is assigned a certain value as a contribution to said property, assuming that it is the same in every compound where it is present. The property of the pure compound is a function of the frequency in which these groups appear and their contributions. In principle, they are additive methods, where the contributions of each group toward property are added to obtain the approximate final value of the property [104–106].

Various prediction methods with GC for physical and thermodynamic properties with a focus on pure lipid compounds have been developed by various authors, among which those reported in **Table 9** stand out.


*Nomenclature: Tc: critical temperature, Pc: critical pressure, Vc: critical volume,Tb: boiling temperature,Tm: melting temperature, ΔH°*f*: standard enthalpy of formation (298 K), ΔG°*f*: standard Gibbs free energy (298 K), C°p: heat capacity, ΔHv: enthalpy of vaporization, ΔSv: entropy of vaporization, ΔHm: enthalpy of fusion, ρL: liquid density μL: liquid viscosity, Pvp: vapor pressure.*

#### **Table 9.**

*Examples of group contribution methods used in lipids and organic compounds in general.*

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*

The range of application and the reliability of these methods depend on several factors [124]:


Another challenge with GC methods is that the selected property model may not have all the necessary parameters, such as groups and/or their contributions, for a specific property, so it is necessary, for the construction of the database of properties, to evaluate these factors when selecting the prediction methods to use. It is important to take into account that, as the number of carbon atoms and unsaturation in the molecule increases, the properties reported in the literature are scarce, so, although it is essential to have predictive models for these cases, the accuracy in the estimation of the properties can decrease, due to the sensitivity that these properties have with the exact conformation of the molecule [104].

#### **5. Conclusions**

The revaluation of waste and by-products, mainly in the food and oleochemical industries, is a fundamental part of the necessary transition toward a more sustainable and circular economic model. The future development of the industry must not neglect social issues and must focus on providing quality and accessible products to the communities that cooperatively represent the workforce and progress of humanity. In conclusion, the revaluation of food waste (fish oil) in a circular economy approach is an opportunity to close the link between food, water, and energy, as well as to incorporate the sustainable perspective to human progress.

#### **Note**

Figures and Tables are original from their authorship.

#### **Author details**

Alicia Román-Martínez Universidad Autónoma de San Luis Potosí, Facultad de Ciencias Químicas, San Luis Potosí, México

\*Address all correspondence to: alicia.romanm@uaslp.mx

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*

#### **References**

[1] Hamm W, Hamilton RJ, Desmet GC. Edible Oil Processing. 2nd ed. New Jersey: Wiley-Blackwell; 2013

[2] O'Brien RD. Fats and Oils. Formulating and Processing for Applications. 3rd ed. Boca Raton: CRC Press; 2008

[3] USDA. United States Department of Agriculture. 2019. Disponible en: www. fas.usda.gov (Consultado: April 2, 2020)

[4] Nonhebel S. On resource use in food production systems: The value of livestock as "rest-stream upgrading system." Ecological Economics. 2004;**48** (2):221-230

[5] Thomas A, Trentesaux D. Are intelligent manufacturing systems sustainable? Studies in Computational Intelligence. 2014;**544**:3-14

[6] Silk D, Mazzali B, Gargalo CL, Pinelo M, Udugama AI, Mansouri SS. A decision-support framework for techno-economic-sustainability assessment of resource recovery alternatives. Journal of Cleaner Production. 2020;**266**(121854):1-18

[7] Udugama IA, Petersen LAH, Falco FC, Junicke H, Mitic A, Alsina XF, et al. Resource recovery from waste streams in a water-energy-food nexus perspective: Toward more sustainable food processing. Food and Bioproducts Processing. 2020;**119**:133-147

[8] Ghisellini P, Cialani C, Ulgiati S. A review on circular economy: The expected transition to a balanced interplay of environmental and economic systems. Journal of Cleaner Production. 2016;**114**(7):11-32

[9] Maina S, Kachrimanidou V, Koutinas A. A roadmap towards a circular and

sustainable bioeconomy through waste valorization. Current Opinion in Green and Sustainable Chemistry. 2017;**8**:18-23

[10] Munir MT, Soheil S, Udugama IA, Baroutian S, Gernaey KV, Young BR. Resource recovery from organic solid waste using hydrothermal processing: Opportunities and challenges. Renewable and Sustainable Energy Reviews. 2018;**96**:64-75

[11] Perederic OA, Mansouri SS, Appel S, Sarup B, Woodley JM, Kontogeorgis GM. Process analysis of Shea butter solvent fractionation using a generic systematic approach. Industrial & Engineering Chemistry Research. 2020;**59**:9152-9164

[12] Sharma YC, Singh B, Madhu D, Liu Y, Yaakob Z. Fast synthesis of high quality biodiesel from "waste fish oil" by single step transesterification. Biofuel Research Journal. 2014;**1**(3):78-80

[13] Venkata Mohan S, Nikhil GN, Chiranjeevi P, Reddy CN, Rohit MV, Kumar AN. Waste biorefinery models towards sustainable circular bioeconomy: Critical review and future perspectives. Bioresource Technology. 2016;**215**:2-12

[14] Jayathilakan K, Sultana K, Radhakrishna K, Bawa AS. Utilization of byproducts and waste materials from meat, poultry and fish processing industries: A review. Journal of Food Science and Technology. 2012;**49**(3): 278-293

[15] Eslick GD, Howe PRC, Smith C, Priest R, Bensoussan A. Benefits of fish oil supplementation in hyperlipidemia: A systematic review and meta-analysis. International Journal of Cardiology. 2009;**136**(1):4-16

[16] Bimbo AP. The production and processing of marine oils. In: Breivik H, editor. Long Chain Omega-3 Specialty Oils. The Oily Press Bridgwater England; 2007. pp. 77-109

[17] Dyerberg J, Bang HO. Haemostatic function and platelet polyunsaturated fatty acids in Eskimos. The Lancet. 1979; **314**(8140):433-435

[18] Farooqui AA. Beneficial Effects of Fish Oil on Human Brain. 1th ed. New York: Springer Science; 2009

[19] Ciriminna R, Meneguzzo F, Delisi R, Pagliaro M. Enhancing and improving the extraction of omega-3 from fish oil. Sustainable Chemistry and Pharmacy. 2017;**5**:54-59

[20] Lands WEM. Fish, Omega-3 and Human Health. 2nd ed. New York: AOCS Press; 2005

[21] Kris-Etherton PM, Harris WS, Appel LJ. Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. Circulation. 2002;**106**(21):2747-2757

[22] Yashodhara BM, Umakanth S, Pappachan JM, Bhat SK, Kamath R, Choo BH. Omega-3 fatty acids: A comprehensive review of their role in health and disease. British Medical Journal. 2009;**85**(March):84-90

[23] Micha R, Khatibzadeh S, Shi P, Fahimi S, Lim S, Andrews KG, et al. Global, regional, and national consumption levels of dietary fats and oils in 1990 and 2010: A systematic analysis including 266 country-specific nutrition surveys. The BMJ. 2014;**348** (g2272):1-20

[24] Grand View Research. Omega 3 Market Size, Share & Trend Analysis Report By Type (EPA, DHA), By Source (Marine, Plant), By Application (Supplements & Functional Foods, Pharmaceuticals, Infant Formulas),

By Region, and Segment Forecasts, 2020-2028. (Industry Analysis Report). 2019

[25] Rubio-Rodríguez N, Beltrán S, Jaime I, Diego SM De, Sanz MT, Carballido, JR. Production of Omega-3 polyunsaturated fatty acid concentrates: A review. Innovative Food Science and Emerging Technologies. 2010;**11**(1):1-12

[26] Tena N, Lobo-Prieto A, Aparicio R, García DL. Storage and preservation of fats and oils. In: Encyclopedia of Food Security and Sustainability. Vol. 2. Elsevier Inc.; 2018. pp. 605-618

[27] Damaceno DS, Perederic OA, Ceriani R, Kontogeorgis GM, Gani R. Improvement of predictive tools for vapor-liquid equilibrium based on group contribution methods applied to lipid technology. Fluid Phase Equilibria. 2018; **470**:249-258

[28] Díaz-Tovar CA, Gani R, Sarup B. Lipid technology: Property prediction and process design/analysis in the edible oil and biodiesel industries. Fluid Phase Equilibria. 2011;**302**(1–2):284-293

[29] Perederic OA, Cunico LP, Kalakul S, Sarup B, Woodley JM, Kontogeorgis GM, et al. Systematic identification method for data analysis and phase equilibria modelling for lipids systems. The Journal of Chemical Thermodynamics. 2018;**121**: 153-169

[30] AOCS. Introduction to the Processing of Fats and Oils. Champaign, Illinois: American Oil Chemists' Society; 2003a

[31] Stankiewicz A, Drinkemburg AAH. Process intensification: History, philosophy, principles. In: Stankiewicz A, Moulijn JA, editors. Re-Engineering the Chemical Processing Plant. 2004. pp. 1-32

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*

[32] Freund H, Sundmacher K. Towards a methodology for the systematic analysis and design of efficient chemical processes. Part 1. From unit operations to elementary process functions. Chemical Engineering and Processing: Process Intensification. 2008;**47**(12):2051-2060

[33] Alfa Laval Inc. Multiple Choice for Fats and Oils Refining: Alfa Laval Degumming and Neutralization Solutions. Sweden. 2010 Report; 2010

[34] Svenson E, Willits J. Nano Neutralization. In Green Vegetable Oil Processing. New York: AOCS Press; 2014. pp. 147-157

[35] Ding H, Ye W, Wang Y, Wang X, Li L, Liu D, et al. Process intensification of transesterification for biodiesel production from palm oil: Microwave irradiation on transesterification reaction catalyzed by acidic imidazolium ionic liquids. Energy. 2018;**144**:957-967

[36] Stavarache C, Vinatoru M, Maeda Y. Aspects of ultrasonically assisted transesterification of various vegetable oils with methanol. Ultrasonics Sonochemistry. 2007;**14**(3):380-386

[37] Armenta RE, Vinatoru M, Burja AM, Kralovec JA, Barrow CJ. Transesterification of fish oil to produce fatty acid ethyl esters using ultrasonic energy. Journal of the American Oil Chemists' Society. 2007;**84** (11):1045-1052

[38] Manjula S, Subramanian R. Membrane technology in degumming, dewaxing, deacidifying, and decolorizing edible oils. Critical Reviews in Food Science and Nutrition. 2006; **46**(7):569-592

[39] Ghasemian S, Sahari MA, Barzegar M, Gavlighi HA. Concentration of Omega-3 polyunsaturated fatty acids by polymeric membrane. International

Journal of Food Science and Technology. 2015;**50**(11):2411-2418

[40] Ivanovs K, Blumberga D. Extraction of fish oil using green extraction methods: A short review. Energy Procedia. 2017;**128**:477-483

[41] Ferdosh S, Sarker ZI, Norulaini N, Oliveira A, Yunus K, Chowdury AJ, et al. Quality of tuna fish oils extracted from processing the by-products of three species of neritic tuna using supercritical carbon dioxide. Journal of Food Processing and Preservation. 2015;**39**(4):432-441

[42] Fiori L, Volpe M, Lucian M, Anesi A, Manfrini M, Guella G. From fish waste to Omega-3 concentrates in a biorefinery concept. Waste and Biomass Valorization. 2017;**8**(8):2609-2620

[43] Riha V, Brunner G. Separation of fish oil ethyl esters with supercritical carbon dioxide. Journal of Supercritical Fluids. 2000;**17**(1):55-64

[44] Oterhals Å, Kvamme B, Berntssen MHG. Modeling of a short-path distillation process to remove persistent organic pollutants in fish oil based on process parameters and quantitative structure properties relationships. Chemosphere. 2010;**80**(2):83-92

[45] Rossi P, Grosso NR, Pramparo M, Del C, Nepote V. Fractionation and concentration of Omega-3 by molecular distillation. In: Bradley TG, Vargas FP, editors. Eicosapentaenoic Acid: Sources, Health Effects and Role in Disease Prevention. 1st ed. Billerica, MA: Nova Biomedical; 2012. pp. 177-203

[46] Solaesa ÁG, Sanz MT, Falkeborg M, Beltrán S, Guo Z. Production and concentration of monoacylglycerols rich in omega-3 polyunsaturated fatty acids by enzymatic glycerolysis and molecular distillation. Food Chemistry. 2016;**190**: 960-967

[47] Bernal JL, Martín MT, Toribio L. Supercritical fluid chromatography in food analysis. Journal of Chromatography A. 2013;**1313**:24-36

[48] Dołowy M, Pyka A. Chromatographic methods in the separation of long-chain mono- and polyunsaturated fatty acids. Journal of Chemistry. 2015;**2015**:1-20

[49] Fagan P, Wijesundera C. Rapid isolation of Omega-3 long-chain polyunsaturated fatty acids using monolithic high performance liquid chromatography columns. Journal of Separation Science. 2013;**36**(11): 1743-1752

[50] Grace & Co., W. R. TRISYL® Silica Gel for Refining Edible Oil. 2011. Disponible en: www.grace.com/food-andbeverage/en-US/edible-oil-refining-aids

[51] Feng X, Patterson DA, Balaban M, Fauconnier G, Emanuelsson EAC. The spinning cloth disc reactor for immobilized enzymes: A new process intensification technology for enzymatic reactions. Chemical Engineering Journal. 2013;**221**:407-417

[52] Xu X. Engineering of enzymatic reactions and reactors for lipid modification and synthesis. European Journal of Lipid Science and Technology. 2003;**105**(6):289-304

[53] Yan X, Zhao X, Ma G, Dai L, Du W, Liu D. Enzymatic ethanolysis of fish oil for selective concentration of polyunsaturated fatty acids (PUFAs) with flexible production of corresponding glycerides and ethyl esters. Journal of Chemical Technology and Biotechnology. 2018;**93**(8): 2399-2405

[54] Stavarache C, Vinatoru M, Nishimura R, Maeda Y. Fatty acids methyl esters from vegetable oil by means of ultrasonic energy. Ultrasonics Sonochemistry. 2005;**12**(5):367-372

[55] Linder M, Matouba E, Fanni J, Parmentier M. Enrichment of salmon oil with n-3 PUFA by lipolysis, filtration and enzymatic re-esterification. European Journal of Lipid Science and Technology. 2002;**104**(8):455-462

[56] Carvalho A, Mimoso AF, Mendes AN, Matos HA. From a literature review to a framework for environmental process impact assessment index. Journal of Cleaner Production. 2014;**64**:36-62

[57] Lewandowski M. Designing the business models for circular economytowards the conceptual framework. Sustainability. 2016;**8**(1):1-28

[58] Khatri P, Jain S. Environmental life cycle assessment of edible oils: A review of current knowledge and future research challenges. Journal of Cleaner Production. 2017;**152**:63-76

[59] Lutze P, Román-Martinez A, Woodley JM, Gani R. A systematic synthesis and design methodology to achieve process intensification in (bio) chemical processes. Computers and Chemical Engineering. 2012;**36**(1):189-207

[60] Mota B, Gomes MI, Carvalho A, Barbosa-Povoa AP. Towards supply chain sustainability: Economic, environmental and social design and planning. Journal of Cleaner Production. 2015;**105**:14-27

[61] Yee KF, Tan KT, Abdullah AZ, Lee KT. Life cycle assessment of palm biodiesel: Revealing facts and benefits for sustainability. Applied Energy. 2009; **86**:S189-S196

[62] Othman MR, Repke JU, Wozny G, Huang YL. A modular approach to

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*

sustainability assessment and decision support in chemical process design. Industrial & Engineering Chemistry Research. 2010;**49**(17):7870-7881

[63] Landucci G, Nucci B, Pelagagge L, Nicolella C. Hazard assessment of edible oil refining: Formation of flammable mixtures in storage tanks. Journal of Food Engineering. 2011;**105**: 105-111

[64] Morais S, Mata TM, Martins AA, Pinto GA, Costa CAV. Simulation and life cycle assessment of process design alternatives for biodiesel production from waste vegetable oils. Journal of Cleaner Production. 2010;**18**(13):1251- 1259

[65] Lee S, Posarac D, Ellis N. Process simulation and economic analysis of biodiesel production processes using fresh and waste vegetable oil and supercritical methanol. Chemical Engineering Research and Design. 2011; **89**(12):2626-2642

[66] Tran NN, Tišma M, Budžaki S, McMurchie EJ, Gonzalez OMM, Hessel V, et al. Scale-up and economic analysis of biodiesel production from recycled grease trap waste. Applied Energy. 2018; **229**:142-150

[67] Schmidt JH. Life cycle assessment of five vegetable oils. Journal of Cleaner Production. 2015;**87**(C):130-138

[68] Banchero M, Kusumaningtyas RD, Gozzelino G. Reactive distillation in the intensification of oleic acid esterification with methanol - a simulation case-study. Journal of Industrial and Engineering Chemistry. 2014;**20**(6):4242-4249

[69] Likozar B, Pohar A, Levec J. Transesterification of oil to biodiesel in a continuous tubular reactor with static mixers: Modelling reaction kinetics,

mass transfer, scale-up and optimization considering fatty acid composition. Fuel Processing Technology. 2016;**142**: 326-336

[70] Martín M, Grossmann IE. Simultaneous optimization and heat integration for the coproduction of diesel substitutes: Biodiesel (FAME and FAEE) and glycerol ethers from algae oil. Industrial and Engineering Chemistry Research. 2014;**53**(28):11371-11383

[71] Diaz-Tovar CA, Ceriani R, Gani R, Bent S. Systematic methodology and property prediction of fatty Systems for Process Design/analysis in the oil and fat industry. Brazilian Journal of Chemical Engineering. 2010;**27**(03):401-412

[72] Shabbir Z, Tay DHS, Ng DKS. A hybrid optimisation model for the synthesis of sustainable gasificationbased integrated biorefinery. Chemical Engineering Research and Design. 2012; **90**(10):1568-1581

[73] Jones M, Forero-Hernandez H, Zubov A, Sarup B, Sin G. Superstructure optimization of Oleochemical processes with surrogate models. Computer Aided Chemical Engineering. 2018;**44**(1):277-282

[74] Kamarden H, Kidam K, Hashim H, Hassim MH, Shahlan SS, Ngadi N, et al. Process simulation of integrated palm oil mill, refinery and oleochemical processes. IOP Conf. Series. Materials Science and Engineering. 2018;**458** (012062):1-6

[75] Barr WJ, Landis AE. Comparative life cycle assessment of a commercial algal multiproduct biorefinery and wild caught fishery for small pelagic fish. International Journal of Life Cycle Assessment. 2018;**23**(5):1141-1150

[76] Sotoft LF, Rong B, Christensen KV, Norddahl B. Process simulation and

economical evaluation of enzymatic biodiesel production plant. Bioresource Technology. 2010;**101**(14):5266-5274

[77] Akoh CC, Min DB. Food Lipids: Chemistry, Nutrition and Biotechnology. 2th ed. New York: Marcel Dekker Inc.; 2002

[78] Gupta MK. Practical Guide to Vegetable Oil Processing. 2nd ed. Elsevier Inc: AOCS Press; 2017

[79] Lee SJ, Ying DY. Encapsulation of fish oils. In: Garti N, editor. Delivery and Controlled Release of Bioactives in Foods and Nutraceuticals. Sawston, Cambridge: Woodhead Publishing Limited; 2008. pp. 370-403

[80] Bhosle BM, Subramanian R. New approaches in deacidification of edible oils - a review. Journal of Food Engineering. 2005;**69**(4):481-494

[81] Bimbo AP. Guidelines for characterizing food-grade fish oil. Inform. 1998;**9**(5):473-483

[82] GOED. GOED best practice guidelines: oxidation control (Reporte 2017). 2017

[83] Blanco-Rodríguez P. Diseño de una planta piloto de refinación de aceites vegetales. (tesis de pregrado). España: Universidad de Cádiz; 2007

[84] Bonilla-Mendez JR, Hoyos-Concha JL. Methods of extraction, refining and concentration of fish oil as a source of omega-3 fatty acids. Corpoica Ciencia y Tecnologia Agropecuaria. 2018;**19**(3): 645-668

[85] Mensink RP, Zock PL, Kester ADM, Katan MB. Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: A

meta-analysis of 60 controlled trials. American Journal of Clinical Nutrition. 2003;**77**(5):1146-1155

[86] Yves H, Korma SA, Ali AH, Tuyishime MA, Habinshuti I, Abed SM. Extraction, refining and purification of ω-3 PUFA through different Techniques – A review. American Journal of Food Science and Nutrition Research. 2016;**4**(1):18-26

[87] International Standards Organization. ISO 5555:2001. Animal and vegetable fats and oils - Sampling. 2001

[88] AOCS. Official method Ca 5a-40. Sampling and analysis of commercial fats and oils: Free fatty acids. American Oil Chemists' Society. 2009a

[89] AOCS. Official method Cd 18-90. Sampling and analysis of commercial fats and oils: Anisidine value. American Oil Chemists' Society. 2003b

[90] AOCS. Official method Cd 8b-90. Sampling and analysis of commercial fats and oils: Peroxide value. American Oil Chemists' Society. 2003d

[91] AOCS. Official method Cd 1d-92. Sampling and analysis of commercial fats and oils: Lodine value of fats and oils cyclohexane-acetic acid method. American Oil Chemists' Society. 2003c

[92] AOCS. Official method Ce 1b-89. Sampling and analysis of commercial fats and oils: Fatty acid composition of marine oils by GLC. American Oil Chemists' Society. 2009b

[93] Young FVK. The Chemical & Physical Properties of crude fish oils for refiners & Hydrogenators. Fish oil bulletin. International Fishmeal and Fishoil Organization (IFFO). 1986;**18**: 1-18

*Oleochemical Processing Technology: From Process Engineering and Intensification… DOI: http://dx.doi.org/10.5772/intechopen.106439*

[94] Suseno SH, Sri Hayati S, Izaki AF. Fatty acid composition of some potential fish oil from production centers in Indonesia. Oriental Journal of Chemistry. 2014;**30**(3):975-980

[95] FAO. Standard for Fish Oils. Food and Agriculture Organization of the United Nations. Codex Alimentarius Commission Report STAN 329-2017. 2017

[96] Schuchardt JP, Hahn A. Bioavailability of long-chain omega-3 fatty acids. Prostaglandins Leukotrienes and Essential Fatty Acids. 2013;**89**(1):1-8

[97] Zhang H, Shen Y, Zhang Y, Li L, Wang X. Regiospecific analysis of fatty acids and calculation of triglyceride molecular species in marine fish oils. BioMed Research International. 2018; **2018**:1-7

[98] Carvajal AK, Mozuraityte R. Fish oils: Production and properties. Encyclopedia of Food and Health. 2016: 693-698

[99] Oterhals Å, Vogt G. Impact of extraction, refining and concentration stages on the stability of fish oil. In: Food Enrichment with Omega-3 Fatty Acids. Sawston, Cambridge: Woodhead Publishing; 2013. pp. 111-129

[100] Ismail A, Bannenberg G, Rice HB, Schutt E, Mackay D. Oxidation in EPA and DHA rich oils: An overview. Lipid Technology. 2016;**28**(3–4):55-59

[101] Laguerre M, Lecomte J, Villeneuve P. Evaluation of the ability of antioxidants to counteract lipid oxidation: Existing methods, new trends and challenges. Progress in Lipid Research. 2007;**46**(5):244-282

[102] Omegavia. How to Buy the Best Fish Oil Supplements – Part 3: Freshness. 2022. Disponible en https://omegavia. com/best-fish-oil-supplement-3/

[103] Cunico LP, Ceriani R, Sarup B, O'Connell JP, Gani R. Data, analysis and modeling of physical properties for process design of systems involving lipids. Fluid Phase Equilibria. 2014;**362**: 318-327

[104] Cunico LP, Hukkerikar AS, Ceriani R, Sarup B, Gani R. Molecular structurebased methods of property prediction in application to lipids: A review and refinement. Fluid Phase Equilibria. 2013; **357**:2-18

[105] Diaz-Tovar CA, Mustaffa AA, Hukkerikar A, Quaglia A, Sin G, Kontogeorgis G, et al. Lipid processing technology: Building a multilevel modeling network. Computer Aided Chemical Engineering. 2011;**29**: 256-260

[106] Pereira E, Meirelles AJA, Maximo GJ. Predictive models for physical properties of fats, oils, and biodiesel fuels. Fluid Phase Equilibria. 2020;**508** (112440):1-20

[107] Lydersen AL. Estimation of critical properties of organic compounds. In: College Engineering University Wisconsin, Engineering Experimental Station, Report 3. Madison, WI: April; 1955

[108] Ambrose D. The correlation and estimation of vapor–liquid critical properties. I. Critical temperatures of organic components. The Journal of Chemical Thermodynamics. Teddington, UK. 1978;**10**(8):765-769

[109] Klincewicz KM, Reid RC. Estimation of critical properties with group contribution methods. AIChE Journal. 1984;**30**(1):137-142

[110] Chein-Hsiun T. Group-contribution estimation of critical temperature with only chemical structure. Chemical Engineering Science. 1995;**50**(22): 3515-3520

[111] Joback KG, Reid RC. Estimation of pure component properties from group contributions. Chemical Engineering Communications. 1987;**57**(1–6):233-243

[112] Constantinou L, Gani R. New group contribution method for estimating properties of pure compounds. AICHE Journal. 1994;**40**(10):1697-1710

[113] Gani R, Marrero J. Groupcontribution based estimation of pure component properties. Fluid Phase Equilibria. 2001;**183**:183-208

[114] Kolská Z, Ruzicka V, Gani R. Estimation of the enthalpy of vaporization and the entropy of vaporization for pure organic compounds at 298.15 K and at Normal boiling temperature by a group contribution method. Industrial & Engineering Chemical Research. 2005; **44**:8436-8454

[115] Kolska Z, Kukal J, Zábranský M, Ruzicka V. Estimation of the heat capacity of organic liquids as a function of temperature by a three-level group contribution method. Industrial & Engineering Chemical Research. 2008; **47**:2075-2085

[116] Ceriani R, Gani R, Meirelles AJA. Prediction of heat capacities and heats of vaporization of organic liquids by group contribution methods. Fluid Phase Equilibria. 2009;**283**(1–2):49-55

[117] Ceriani R, Gonçalves CB, Coutinho JAP. Prediction of viscosities of fatty compounds and biodiesel by group contribution. Energy and Fuels. 2011; **25**(8):3712-3717

[118] Ceriani R, Gani R, Liu YA. Prediction of vapor pressure and heats of vaporization of edible oil/fat compounds by group contribution. Fluid Phase Equilibria. 2013;**337**:53-59

[119] Zeberg-Mikkelsen CK, Stenby EH. Predicting the melting points and the enthalpies of fusion of saturated triglycerides by a group contribution method. Fluid Phase Equilibria. 1999; **162**:7-17

[120] Moorthy AS, Liu R, Mazzanti G, Wesdorp LH. Estimating thermodynamic properties of pure triglyceride systems using the triglyceride property calculator. Journal of the American Oil Chemists' Society. 2016;**94**(2):187-199

[121] Wittig R, Lohmann J, Gmehling J. Vapor-liquid equilibria by UNIFAC group contribution. 6. Revision and extension. Industrial and Engineering Chemistry Research. 2003;**42**(1): 183-188

[122] Magnussen T, Rasmussen P, Fredenslund A. Unifac parameter table for prediction of liquid-liquid equilibria. Industrial and Engineering Chemistry Process Design and Development. 1981; **20**(2):331-339

[123] Gmehling J, Li J, Schiller M. A modified UNIFAC model. 2. Present parameter matrix and results for different thermodynamic properties. Industrial and Engineering Chemistry Research. 1993;**32**(1):178-193

[124] Hukkerikar AS, Sarup B, Ten Kate A, Abildskov J, Sin G, Gani R. Groupcontribution + (GC +) based estimation of properties of pure components: Improved property estimation and uncertainty analysis. Fluid Phase Equilibria. 2012;**321**:25-43

#### **Chapter 2**
