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Article

Environmental and Economic Analysis of the Production of Oregano Oil Microparticles

by
Hugo José Martins Carvalho
1,
Filipe Hobi Bordon Sosa
2,*,
Paula Quinteiro
3,
Ana Cláudia Dias
3,
Mario Antonio Torres-Acosta
4,5,
João Henrique Picado Madalena Santos
6,* and
Joyce Maria Gomes da Costa
1
1
Institute of Science and Technology, University of Federal dos Vales Jequitinhonha e Mucuri (UFVJM), Diamantina 39100-000, MG, Brazil
2
CICECO–Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
3
CESAM–Centre for Environmental and Marine Studies, Department of Environment and Planning, University of Aveiro, 3810-193 Aveiro, Portugal
4
The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Torrington Place, London WC1E 6BT, UK
5
Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, Av. Eugenio Garza Sada 2501 Sur, Monterrey 64849, Nuevo León, Mexico
6
Department of Biochemical and Pharmaceutical Technology, São Paulo University, Av. Prof. Lineu Prestes n 580 Bloco 16, São Paulo 05508-000, SP, Brazil
*
Authors to whom correspondence should be addressed.
Sustainability 2024, 16(18), 8038; https://doi.org/10.3390/su16188038
Submission received: 13 August 2024 / Revised: 10 September 2024 / Accepted: 11 September 2024 / Published: 14 September 2024
(This article belongs to the Section Bioeconomy of Sustainability)
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Abstract

:
The interest in using essential oils for biotechnological and biomedical applications has been increasing because of their unique properties, such as their roles as preservatives, antioxidants, antimicrobial agents, and therapeutic agents, with oregano oil being a notable example. However, the bioactivity and stability of oregano oil can be compromised because of its volatile nature and external factors like exposure to light, heat, or oxygen. To protect oregano oil from these adverse effects and enhance its potential, microencapsulation has been employed. Nevertheless, studies evaluating the economic feasibility of this process are still limited. In this context, this study combines an environmental impact assessment by applying the life cycle assessment (LCA) methodology and an economic evaluation of three different scenarios (A, B, and C) for the production of oregano oil microparticles by a spray dryer. In Scenario A, only modified starch was used to prepare the emulsion; in Scenario B, the modified starch was replaced with gum arabic; and in Scenario C, the gum arabic, maltodextrin, and modified starch were combined. The results indicated that Scenario B presents the best environmental performance for all impact categories analyzed (global warming, fossil resource scarcity, mineral resource scarcity, terrestrial acidification, freshwater eutrophication, and marine eutrophication). However, the composting of bio-waste end-of-life presents better environmental performance for the other scenarios (A and C). In Scenario B, the process with the lowest production cost per gram of microcapsules is the most promising for meeting the demands of the aspects analyzed.

1. Introduction

Encapsulation technology is widely used to protect and stabilize sensitive materials and produce ingredients suitable for food applications [1,2]. More recently, the microencapsulation technique has been widely studied, allowing for an increase in the stability of materials through coatings (wall material) that limit the interaction of substances susceptible to air, humidity, and other environmental variations [3,4]. This technique also minimizes the effects of high temperatures and reduces water activity, thus reducing microbial growth and storage and transport costs [5,6]. In addition, microencapsulation allows for the use of these compounds in foods that would be incompatible with them because of the pH or solubility of the compounds [3,7].
In the last two decades, the applications of microencapsulation have increased exponentially. Nowadays, this procedure is used in different industries, such as food (functional compounds, additives, dyes, flavors) [8], textiles [9], pharmaceuticals (vaccines) [10], cosmetics [11], and agrochemicals [12], allowing for the use of substances that would otherwise be unfeasible, such as some compounds sensitive to heat, temperature, and pH [13,14,15].
Among the main encapsulated food ingredients, essential oils stand out, as they are substances rich in organic structures and active principles. They present a chemical composition rich in aromatic constituents and terpenes, in addition to high volatility [16,17]. One of the best known is oregano essential oil, which has antimicrobial, acaricidal, antioxidant, and anti-inflammatory properties, mainly attributed to carvacrol and thymol [17,18]. The wall material and encapsulation process are applied to have a direct influence on the properties of the microparticles, such as their molecular structure (molecular weight and electrical charge), physical state (boiling and melting points), biological structure (antimicrobial activity and bioactivity), solubility and activity, surface properties, optical properties, and chemical stability (oxidation and hydrolysis) [1,19]. In general, the literature reports that the microencapsulation of these compounds results in the improved stability and antimicrobial activity of oregano essential oil [20], and the most applied method in microencapsulation is spray drying [21,22,23].
However, studies available in the literature are limited to reporting the properties and characteristics of microencapsulation [24,25,26,27]. For example, Almeida et al. [28] evaluated the microencapsulation of oregano essential oil in starch. The authors only studied the effect of operating conditions (temperature, pressure, certainty, time, proportion of EO mass/starch, and mode of depressurization), and the environmental impact was not considered. An environmental impact assessment is important because, during the process, pesticides can be transported to rivers causing water contamination and gas emissions, besides effects that contribute to the intensification of global warming [29]. So far, no LCA study has evaluated the potential environmental impacts of the production of oregano essential oil microparticles using different encapsulants. Although the production of oregano essential oil microparticles has application benefits, particularly for reducing greenhouse gas emissions, it also has potential environmental impacts that must be evaluated from the point of view of the production process [29].
In the literature, few studies report the economic viability of this kind of process [30,31,32]. The economic evaluation of processes is a remarkable tool that has been used to determine the feasibility and potential applicability of processes. The Biosolve Process (Biopharm Services, Buckinghamshire, U.K.) is an alternative to providing a model focused on economically relevant parameters [33].
Using economic and environmental analysis to study microparticle encapsulation processes can help to identify a process with low impact and cost, thus contributing to better development. In addition, it is possible to evaluate different scenarios and assess their costs and impacts on the process, allowing the development of control strategies and preventing future troubles [33].
Borges et al. [34] reported the characterization of fresh and dried basil, oregano, and thyme plants and obtained essential oils through the steam dragging method. The authors found that dried oregano leaves have the potential to obtain essential oils and enrich foods. In another study, Zheljazkov et al. [35] determined the best condition to extract essential oregano oil from leaves or buds by steam distillation. The authors studied the effect of time on the yield and composition of the antioxidant activity of oregano essential oil. The maximum yield of low-boiling constituents was reached in short distillation times (<2.5 min), whereas the concentration of other higher-boiling constituents was maximum in 5 to 20 min. The maximum yield of essential oil from steam-distilled oregano leaves could be obtained in 240 min of distillation. Additionally, the total amount of antioxidant agents also increased with higher oil yields, supporting longer distillation time application for oregano-based oil extractions.
Costa et al. [36] reported the best combination of encapsulants for the microencapsulation of oregano essential oil by spray-drying with the addition of gum arabic (GA), modified starch (MS), and maltodextrin (MA). The authors reported that the mixture of 62.5% GA and 37.5% MA was the most efficient blend, with carvacrol being the major phenolic compound in oregano essential oil with a 58% maximum concentration in microparticles. The use of GA increased the microencapsulation efficiency by up to 93%. Furthermore, MA was identified as an alternative for stabilizing oregano essential oil, resulting in good microparticles with physical properties. The combination of MA and GA allowed for increasing the microcapsule solubility in water and oil retention. Regarding the properties, the oregano essential oil microparticle showed low water activity (<0.17%), formed by a porous structure with low density, rough surface, and good encapsulation capacity.
Given the above, there is an increasing demand for the food industry to quantify the environmental and economic impacts of the production of food ingredients. Thus, the food industry needs to adapt to the most advantageous process in both aspects, requiring further studies with these analyses. In the case of producing oregano essential oil microparticles, it is essential to know their characteristics in terms of their potential and limitations and to analyze the best production option with the lowest impact on the environment. In this sense, this study assesses the potential environmental impacts and economic costs generated by the production of microparticles formulated in three different scenarios through spray drying, from the essential oil extraction stage to the emulsion preparation and the microencapsulation process of essential oil of oregano.

2. Materials and Methods

The oregano essential oil microparticles process, which was evaluated using economic and environmental analyses, was developed based on previous studies in the literature [34,35,36]. Based on these works, the proposed process consisted of three main steps. Step 1 consisted of the oregano essential oil extraction process, followed by emulsion preparation (step 2) and, finally, the spray-drying step (step 3) (Figure 1). Each of the steps is detailed below.

2.1. Extraction of Oregano Essential Oil (Step 1)

First, the oregano (Origanum vulgare) leaves were dried following the methodology described by Borges et al. [34] and the Association of Official Analytical Chemists (AOAC) methodology [37]. In this process, the humidity of the leaves was standardized to a humidity of approximately 9.4%.
After drying the leaves, the oregano oil extraction process started using the methodology and parameters described by Zheljazkov et al. [35]. The oregano leaves, together with water, were extracted with the traditional method of steam distillation using a 2 L steam distillation Clevenger-type apparatus. After an extraction time of 240 min, given the best oil yield (content) per 100 g of dry oregano leaves, the concentrated oregano essential oil and the residue of the leaves of the process were finally obtained. With this process, it was possible to obtain an average yield of 2.8 mL of oregano oil per 100 g of dried leaves. It is important to highlight that the methodology applied in this process allowed for the water to be reused in the process.

2.2. Emulsion Preparation (Step 2)

After obtaining the oregano oil, an emulsion was prepared following the methodology described by Da Costa et al. [36]. In this step, three different scenarios were considered. The choice of encapsulants was based on the methodology described by Hijo et al. [38], especially considering the wide applications of this oil in different industry sectors, such as food, pharmaceuticals, and cosmetics.
In Scenario A (modified starch + oregano essential oil), the modified starch was hydrated in distilled water for 12 h under refrigeration at 10–12 °C. Then, these ingredients were dissolved in distilled water at 60 °C using the Ultra Turrax homogenizer at a speed of 20,000 rpm for 30 min. The modified starch was added at 82 °C, maintaining homogeneity until complete dissolution of the wall materials. Subsequently, they were refrigerated to a temperature below 10 °C, at which point the oregano essential oil was added, rotating at 20,000 rpm for 5 min, until a completely homogeneous emulsion was obtained.
In Scenario B (gum arabic + oregano essential oil), the procedure was performed using the same parameters as in Scenario A; however, the encapsulating material used was gum arabic in the binding of modified starch. In Scenario C (gum arabic + maltodextrin + modified starch + oregano essential oil), first, maltodextrin (MA) and GA (gum arabic) were hydrated in distilled water for 12 h under refrigeration at 10–12 °C. Then, these ingredients were dissolved in distilled water at 60 °C using the Ultra Turrax homogenizer at a speed of 20,000 rpm for 30 min. In the second step, the modified starch was added at 82 °C, maintaining homogeneity until complete dissolution of the wall materials. Subsequently, they were refrigerated to a temperature below 10 °C, at which point the oregano essential oil was added, rotating at 20,000 rpm for 5 min, until a completely homogeneous emulsion was obtained.

2.3. Drying by a Spray Dryer (Step 3)

The last step (3) consisted of drying the formed emulsion. For this, the literature recommended using a LABMAQ Spray Dryer Brasil 1.0 MSD (Ribeirão Preto, São Paulo, Brazil), equipped with a nozzle of 1.2 × 103 m in diameter [36]. The compressed air pressure for the spray stream was set to 5 bar. The inlet and outlet air temperatures were maintained at 180 °C and 105 °C, respectively, and the feed rate was adjusted to 2.97 × 10−7 m3s−1. The air intake rate was maintained at 5.8 × 10−4 m3s−1. The powders obtained for each treatment were stored under refrigeration (4–7 °C) in glass vials protected from light and gas permeation to minimize possible changes in the material, such as agglomeration, caused by water absorption and oxidation.

2.4. Environmental Assessment

When the industrial production of oregano oil microparticles is envisaged, it is important to develop an efficient process and also to evaluate the environmental impact of the proposed process. In this context, life cycle assessment (LCA) was applied following the ISO 14040 standard [39] with the objectives of assessing the potential environmental impacts of the production of oregano oil microparticles and understanding the effect of using different encapsulants. LCA consists of the compilation and evaluation of the inputs, outputs, and corresponding environmental impacts of a product throughout its life cycle, i.e., from raw material acquisition to production and up to end-of-life (EoL).
The following scenarios for the production of oregano oil microparticles were analyzed:
  • The production of oregano essential oil (OEO) microparticles using modified starch (MS) during the emulsion preparation stage;
  • The production of OEO microparticles using gum arabic (GA) during the emulsion preparation stage;
  • The production of OEO microparticles using MS, GA, and maltodextrin (MD) during the emulsion preparation stage.
In all scenarios, extraction of the essential oil, preparation of the emulsion, and microencapsulation stages were assessed. The extraction of the essential oil and microencapsulation process resulted in the production of biowaste, i.e., oregano leaves, and oil waste and leads to encapsulant losses. Two EoL (end-of-life) alternatives of the biowaste—landfilling and composting—were considered for each scenario. LCA includes the production of oregano, MS, GA, MD, tap water, packaging, and electricity. Data on the number of raw materials, tap water, packaging, electricity consumed by the equipment used, and biowaste were obtained during the experiment and from equipment catalogs (Table 1). Data for oregano cultivation were collected from a similar crop available in the Ecoinvent database [40], adapted for the typical tillage of an oregano crop in Brazil based on expert knowledge.
Data on the impacts of GA production and packaging, including its transport, were collected from Harmand et al. [41], Sarr et al. [42], and Wernet et al. [40]. GA is imported from Senegal; therefore, the type of transport used and the distances traveled are shown in Table 2. Inventory data were taken from the Ecoinvent database [40].
Data on the inputs and outputs of MD were sourced from Smrcková et al. [43], and the impacts of each flow were obtained in Ecoinvent [40]. Data on the impacts of MS, electricity generation (Brazil profile), Kraft paper to pack the microencapsulated essential oregano oil, and biowaste treatment were sourced from the Ecoinvent database [40].
The ReCiPe 2016 midpoint method from the Hierarchist perspective [44] was used to translate environmental emissions and resource extraction into environmental impacts. The impact categories selected for analysis comprise global warming (GW) (equivalent to the carbon footprint), fossil resource scarcity (FRS), mineral resource scarcity (MRS), terrestrial acidification (TA), freshwater eutrophication (FE), and marine eutrophication (ME). GW was selected because of its relevance in the evaluation of global climate change effects. The remaining impact categories were selected to obtain a comprehensive and consistent environmental assessment of oregano oil microparticles. The impacts derived from the production of 1 g of oregano essential oil microparticles were calculated with SimaPro software20 based on the respective amounts of inputs and outputs presented in Table 1 multiplied by the respective impact factors for each impact category considered (e.g., mass of greenhouse gas emissions expressed as carbon dioxide equivalent (CO2 eq) per mass of product).

2.5. Economic Evaluation

Production costs were calculated based on a methodology published before [45]. Briefly, the modeled processes relied on the basis presented in Figure 1 and Table S1. To obtain production costs, 4 cost categories were fulfilled (capital contribution, materials and consumables, labor, and others—which mainly encompass waste management and utilities). The quantity of materials needed per batch was calculated and extrapolated to different amounts of oregano (between 1 to 1000 kg) leaves processed based on the scenarios presented in Figure 1. This work was based only on the equipment needed for the capital contribution (Table 3). To determine the cost of the equipment required, the cost of several scales was collected, and regression equations were calculated. Then, according to the amount of oregano leaves to be processed, the equipment cost was adjusted accordingly.
Additionally, to estimate the capital contribution per batch, the total sum of equipment cost was considered as a bulk amount to estimate a loan payment with 10 years (with each year having 300 operative days) and a 12% interest rate. For labor and the “others” categories, their contributions were based on reports that approximated 15% and 4% of the total production costs, respectively [46]. The complete data used for the economic modeling can be found in Table 3. These data provided a production cost per batch, which was converted to a production cost per gram of microcapsules (final mixture of oregano essential oil + corresponding encapsulating materials) by using the product generated at the end of a batch in each scenario.
A sensitivity analysis was performed using the average of the material prices as a base scenario with the worst and best scenarios being the average plus or minus one standard deviation (between the lowest and highest prices included in Table 3, respectively. The last section comprises a return analysis using as a base Equation (1).
R = P r o d u c t   C o m m e r c i a l   P r i c e × P r o d u c t   g e n e r a t e d   − ( P r o d u c t i o n   C o s t × C o s t   M u l t i p l i e r )
Equation (1) allows for determining a potential profit (or return) assuming a commercial price for the product of interest and the amount of product generated. Negative cash flows were determined by the product costs calculated here and an additional term named “cost multiplier” to capture the possibility that actual production costs are higher or lower than calculated. Given the current state of the development of the microcapsule developed in this work, we decided to modify Equation (1) to identify the necessary commercial price of the product and obtain a return equal to zero. This modification generated the threshold price that this development must aim to achieve given the current development. To further enhance the impact of this analysis, a cost multiplier was included ranging from 5-fold higher to lower than the calculated production costs.

3. Results and Discussion

3.1. Environmental Assessment

The results of the environmental impacts are expressed per 1 g of the produced oregano essential oil microparticles, allowing a direct comparison of the scenarios studied. Figure 2 and Table S2 shows the relative contribution of each stage to the total impacts. Overall, regardless of the EoL alternative, Scenario B presents the lowest impacts for all the impact categories, followed, in this order, by Scenario C and A. The comparison of the EoL alternatives of biowaste shows that, for all scenarios, composting presents lower environmental impacts for ME and GW, reaching a reduction of around 17% for ME (due to lower emissions of nitrate and ammonium to water) and around 7% for GW (due to lower emissions of methane and nitrous oxide to air) compared with landfilling. However, composting increases TA by around 4% (because of higher ammonia emissions) in comparison with landfilling. For the remaining impact categories, the impacts of biowaste landfilling and composting are similar.
For all scenarios and EoL alternatives, both essential oil extraction and the microencapsulation stages (Figure 2) are particularly relevant for all impact categories other than ME with contributions ranging from 38% (Scenario C with landfilling and composting alternatives for FRS) to 55% (Scenarios A and B with composting for TA) and from 35% (Scenario C with composting for TA) to 50% (Scenario B with composting for FE) of the total impact, respectively. For ME, essential oil extraction is the main contributor, ranging from 86% (Scenario A with landfilling) to 96% (Scenario B with composting) of the total impact. As observed by previous authors, FE and ME are intrinsically connected to the kg amount of P and N generated and were found to be present in vegetable oil extraction studies [47,48].
Figure 3 shows that for all scenarios, electricity consumption, mainly during the microencapsulation stage, has the most relevant share for all impact categories except ME, presenting contributions in those categories that range from 66% to 92% of the total impact. Oregano cultivation is also important for MRS in Scenario A, with a contribution of 11% of the total impact, and for TA in all scenarios, contributing around 23% of the total impact because of the application of organic fertilizers to oregano crops. For GW, biowaste landfilling is also relevant in Scenario A, with a contribution of 17% of the total impact. For FE, this latter EoL alternative in Scenario C presents a contribution of 8% of the total impact. For ME, the main contribution comes from oregano cultivation, with an average of 80%, mainly because of the use of organic fertilizers during oregano growth, which leads to emissions of nitrate to water from fertilizer leaching. Furthermore, the biowaste disposed at landfills contributes around 18% of this impact category.

3.2. Economic Analysis

The first analysis was performed to contrast the three options of microencapsulation processes developed in this work. Figure 4 shows the results of this contrast. The process with the lowest production cost per gram of microcapsules is the one based solely on GA. This is a consequence of the increased amount of product generated from this process option. Even though GA is the most expensive material used in the construction of microcapsules, the low amounts employed together with the increased amount of product generated give it an advantage over the other processes. Moreover, when using MS alone, the yield is lower than the combination of the three materials, thus increasing production costs per gram of the final product. Additionally, when using the three materials simultaneously, the yield is higher and the amount of each material is reduced, which decreases the costs as well.
Additionally, Figure 4 shows that the production cost for all process options (as the only difference among them is the materials used and the amount of product) tends to stabilize relatively at a low amount of processed oregano leaves. This indicates that for future developments maintaining the current conditions, the production cost will vary minimally at larger scales. Given the unit operations employed in these processes (dilutions and mixing), production yields can be maintained at large scales similar to their laboratory counterparts.
The second analysis consisted of generating different scenarios using a range of prices for the materials employed here. This consisted of using the average plus/minus one standard deviation calculated from the range of values for each presented in Table 3. To emphasize the potential of the economy of scales, the results are presented as the difference between the production costs per batch calculated using the worst scenario (average plus one standard deviation) and the best scenario (average minus one standard deviation). These results are presented in Figure 5.
Given the elevated price of gum arabic, the potential range of variation is also greater, which resulted in it having a deeper impact on the range of production costs per batch. Given the results presented here, it is important that the negotiated material prices remain low when designing larger processes. Ultimately, this can benefit a company’s finances. Although its impact cannot be seen easily when considering a production cost per unit mass of product, when changed to a batch basis, this phenomenon becomes relevant.
Lastly, using Equation (1), the potential commercial price needed for the microparticles to obtain a return equal to zero was calculated for the GA-based process. Additionally, five multipliers for the production cost were employed—0.2X, 0.5X, 1X (base production cost), 2X, and 5X. The inclusion of the multipliers helped to observe the impact of having a higher or lower production cost in practice. Moreover, given the structure of the equation, this multiplier can also be applied in an opposite manner to the production objective (i.e., an increase of 5X of the production cost will be equivalent to a decrease of 5X—or the 0.2X multiplier—in the product titter). This calculation provided the threshold needed to obtain a positive income. Additionally, this served as a guide to determine what needs to be done to reduce the threshold. The results are presented in Figure 6.
The general trend is similar to the behavior described by the production cost per gram in Figure 4. Moreover, it is critical that the variations in the mentioned multipliers have a very deep impact on the estimated commercial price. Given the current developments, and using the base conditions, an approximate commercial price of USD 2.2 per gram of microcapsules is needed, but this can be improved to USD 0.44 if the actual production cost is decreased five times. To accomplish this the GA-based process needs to improve by developing a more efficient extraction of the essential oil and the microencapsulation process in the spray dryer. This economic evaluation helped provide guidance for future developments and a framework to direct future investments and resources.

4. Conclusions

The environmental impact of the industrial scale-up of the emulsion and oregano oil microencapsulation process was assessed with LCA, considering three distinct production scenarios and two EoL alternatives (landfilling and composting). The LCA results indicate that Scenario B (production of oregano microencapsulation particles using GA during the emulsion preparation stage) presented the best environmental performance for all the impact categories analyzed. Nevertheless, within this scenario, biowaste composting at the EoL presented a better environmental performance for ME and GW, and no relevant difference between these two EoL alternatives was observed for the remaining impact categories. The results of the economic analysis showed that production costs tended to stabilize relatively at low quantities of processed oregano leaves.
Overall, combining economic and environmental analysis in the context of microencapsulation reveals that it is important to consider both types of factors when making decisions about the use of this technology in order to achieve a sustainable and balanced outcome.
Research on the stability and quality of microparticles by spray drying should be further investigated. However, recent studies have shown trends that can improve production such as the use of different encapsulation methods, variation in operational conditions, and the influence of new encapsulants.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/su16188038/s1. The supplementary data are composed of two tables: Table S1: Inputs and outputs from the production of 2.5 g of maltodextrin used in Scenario C, and Table S2: Life cycle assessment results for the production of 1 g of oregano essential oil microparticles in the three scenarios analyzed and end-of-life alternatives of the biowaste.

Author Contributions

H.J.M.C.: methodology, investigation, and data curation; F.H.B.S.: conceptualization, methodology, investigation, data curation, writing—original draft, and visualization supervision; P.Q.: conceptualization, methodology, investigation, and data curation; A.C.D.: conceptualization, methodology, investigation, and data curation; M.A.T.-A.: conceptualization, methodology, investigation, and data curation; J.H.P.M.S.: conceptualization, data curation, writing—review and editing, supervision, and funding acquisition; J.M.G.d.C.: writing—review and editing, supervision, and funding acquisition. All authors have read and agreed to the published version of the manuscript.

Funding

The authors would like to acknowledge the Portuguese Foundation for Science and Technology (FCT)/MCTES for the financial support to CESAM (UIDP/50017/2020+UIDB/50017/2020+LA/P/0094/2020) through national funds. Paula Quinteiro, Ana Cláudia Dias and Filipe Hobi Bordon Sosa also thank FCT/MCTES for contracts CEECIND/00143/2017, CEECIND/02174/2017 and CEECIND/07209/2022, respectively. The authors also wish to thank FAPEMIG (Project Universal APQ-03329-16), CAPES, CNPq and the Institute of Science and Technology (UFVJM) for supporting this study.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in the study are included in the article/Supplementary Materials, further inquiries can be directed to the corresponding authors.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Process diagram of oregano essential oil microparticle production considering 3 different scenarios. Scenario A: modified starch + oregano essential oil; Scenario B: gum arabic + oregano essential oil; Scenario C: gum arabic + maltodextrin + modified starch + oregano essential oil.
Figure 1. Process diagram of oregano essential oil microparticle production considering 3 different scenarios. Scenario A: modified starch + oregano essential oil; Scenario B: gum arabic + oregano essential oil; Scenario C: gum arabic + maltodextrin + modified starch + oregano essential oil.
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Figure 2. The relative contribution of (■) microencapsulation, (■) preparation of the emulsion, and (■) essential oil extraction stage within the process to the total impacts. Acronyms: GW = global warming; FRS = fossil resource scarcity; MRS = mineral resource scarcity; TA = terrestrial acidification; FE = freshwater eutrophication; ME = marine eutrophication.
Figure 2. The relative contribution of (■) microencapsulation, (■) preparation of the emulsion, and (■) essential oil extraction stage within the process to the total impacts. Acronyms: GW = global warming; FRS = fossil resource scarcity; MRS = mineral resource scarcity; TA = terrestrial acidification; FE = freshwater eutrophication; ME = marine eutrophication.
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Figure 3. Relative contribution of the inputs and outputs for the life cycle assessment results. Acronyms: GW = global warming; FRS = fossil resource scarcity; MRS = mineral resource scarcity; TA = terrestrial acidification; FE = freshwater eutrophication; ME = marine eutrophication.
Figure 3. Relative contribution of the inputs and outputs for the life cycle assessment results. Acronyms: GW = global warming; FRS = fossil resource scarcity; MRS = mineral resource scarcity; TA = terrestrial acidification; FE = freshwater eutrophication; ME = marine eutrophication.
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Figure 4. The contrast of the production cost per gram of microcapsules for the 3 options analyzed at different amounts of processed oregano leaves.
Figure 4. The contrast of the production cost per gram of microcapsules for the 3 options analyzed at different amounts of processed oregano leaves.
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Figure 5. Impact of having different costs for materials for the 3 process options analyzed (MS, GA, and MS + GA + MD). Data represent the difference between the highest and lowest production costs calculated on each production scale.
Figure 5. Impact of having different costs for materials for the 3 process options analyzed (MS, GA, and MS + GA + MD). Data represent the difference between the highest and lowest production costs calculated on each production scale.
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Figure 6. Results for the return analysis determining the necessary commercial price for the microcapsules in order to obtain a return equal to zero. Different lines show the results at different multipliers for current production costs. The Y-axis is presented on the logarithmic scale to simplify the presentation.
Figure 6. Results for the return analysis determining the necessary commercial price for the microcapsules in order to obtain a return equal to zero. Different lines show the results at different multipliers for current production costs. The Y-axis is presented on the logarithmic scale to simplify the presentation.
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Table 1. Inputs and outputs from the production of 1 g of oregano essential oil microparticles for the three scenarios analyzed.
Table 1. Inputs and outputs from the production of 1 g of oregano essential oil microparticles for the three scenarios analyzed.
Stages UnitScenario AScenario BScenario C
Essential oil extractionInputs
Oreganosg137.478.4117.6
ElectricityWh579.6330.8496.2
Outputs
Oregano essential oilg0.90.50.8
Oregano waste to landfillg37.621.532.2
Water vapor in the airg98.956.584.7
Preparation of the emulsionInputs
Modified starchg8.8-2.5
Gum arabic (GA)g-5.12.5
Maltodextrin (MD)g--2.5
Tap waterg171.798.0147.0
ElectricityWh68.026.258.2
Outputs
Emulsiong88.550.575.8
MicroencapsulationInputs
ElectricityWh708.0404.0606.1
Kraft paperg0.10.10.1
Outputs
Oil encapsulated microparticlesg1.01.01.0
Wasteg8.74.67.3
Water vapor in the airg78.844.967.4
Wastewater unpollutedg92.9253.0379.55
Table 2. Transport profile for gum arabic (GA) used in Scenarios B and C.
Table 2. Transport profile for gum arabic (GA) used in Scenarios B and C.
MaterialDistance (km)Transport Mode
GA from plantation to port of Dakar, Senegal150Lorry (16–32 t)
GA from the port of Dakar, Senegal, to the port of Rio de Janeiro5144Transoceanic ship
GA from port of Rio de Janeiro to Minas Gerais640Lorry (16–32 t)
Table 3. Data used to perform the economic evaluation. The data include equations to estimate costs of equipment, materials from different sources, labor, and others.
Table 3. Data used to perform the economic evaluation. The data include equations to estimate costs of equipment, materials from different sources, labor, and others.
Cost CategoryItemCost Data
Equipment
OvenUSD 258 per 30 L size
Steam distiller P r i c e   U S D = − 0.001 × X 2 + 5.4604 × X + 590.66
X = Amount of steam required in liters
RefrigeratorUSD 262 per 240 L size
Homogenizer P r i c e   U S D = 1087.8 × L n Y + 602.09
Y = Mixture of material for microencapsulation and OEO
Spray dryer P r i c e   U S D = 3224.4 × e 0.0039 * Y
Y = Mixture of material for microencapsulation and OEO
Materials (All prices in USD per kg)
Oregano leaves15–25 (Niu Zhi Natural Species)
Modified starch0.33–0.34 (shorturl.at/hxzA3)
0.5–1.5 (shorturl.at/uKL36)
Gum arabic11–29 (shorturl.at/blsuO)
11–19 (shorturl.at/pKS16)
6–15 (shorturl.at/jvCMS)
11–29 (shorturl.at/cvBEV)
Maltodextrin0.44 (shorturl.at/hjlCV)
1.66 (shorturl.at/nyHL5)
0.45–0.7 (shorturl.at/uxIKU)
0.35–0.4 (shorturl.at/iuEJX)
Water (distilled and for steam)0.96
Labor-
Fixed at 15% of total cost
Others-
Fixed at 4% of total cost
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Carvalho, H.J.M.; Sosa, F.H.B.; Quinteiro, P.; Dias, A.C.; Torres-Acosta, M.A.; Santos, J.H.P.M.; da Costa, J.M.G. Environmental and Economic Analysis of the Production of Oregano Oil Microparticles. Sustainability 2024, 16, 8038. https://doi.org/10.3390/su16188038

AMA Style

Carvalho HJM, Sosa FHB, Quinteiro P, Dias AC, Torres-Acosta MA, Santos JHPM, da Costa JMG. Environmental and Economic Analysis of the Production of Oregano Oil Microparticles. Sustainability. 2024; 16(18):8038. https://doi.org/10.3390/su16188038

Chicago/Turabian Style

Carvalho, Hugo José Martins, Filipe Hobi Bordon Sosa, Paula Quinteiro, Ana Cláudia Dias, Mario Antonio Torres-Acosta, João Henrique Picado Madalena Santos, and Joyce Maria Gomes da Costa. 2024. "Environmental and Economic Analysis of the Production of Oregano Oil Microparticles" Sustainability 16, no. 18: 8038. https://doi.org/10.3390/su16188038

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