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Drying Methods of Coffee Extracts and Their Effects on Physicochemical Properties: A Review

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Dian Shofinita at Bandung Institute of Technology
Dian Shofinita
Dianika Lestari at Bandung Institute of Technology
Dianika Lestari
Lienda Aliwarga
Lienda Aliwarga
Lienda Aliwarga
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Giovanni Arneldi Sumampouw
Giovanni Arneldi Sumampouw
Giovanni Arneldi Sumampouw
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Drying is one of the key steps in the coffee production process. It is necessary to dry the coffee extracts to prevent microbial growth and to prolong the storage time of coffee. To this date, mechanical drying methods have been developed and employed in industries to shorten the drying time. However, these drying methods could alter the physicochemical properties of coffee and the compounds present in coffee. Therefore, it is crucial to maintain these factors in the coffee production process as they affect the stability, reconstitution, and aroma of the coffee produced. These properties are crucial as they determine the final quality of coffee. This review will focus on the effect of spray-drying, freeze-drying, and spray-freeze–drying on the physicochemical properties of coffee such as morphology, particle size, moisture content, bulk density, and compound retention. Effects on organoleptic properties are also discussed. Possible advancements to these drying methods such as the encapsulation process, the use of a porous frozen sample, and total solid enhancement of the raw material have been highlighted.
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Vol.:(0123456789)
1 3
Food and Bioprocess Technology (2024) 17:47–72
https://doi.org/10.1007/s11947-023-03067-4
REVIEW
Drying Methods ofCoffee Extracts andTheir Effects
onPhysicochemical Properties: AReview
DianShofinita1,2· DianikaLestari1,2· LiendaAliwarga1,2· GiovanniArneldiSumampouw1,2·
SekarArumAmbarwati1· KarenChristineGunawan1· AmarthyaBenignaAchmadi2
Received: 16 August 2022 / Accepted: 11 March 2023 / Published online: 11 May 2023
© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2023
Abstract
Drying is one of the key steps in the coffee production process. It is necessary to dry the coffee extracts to prevent microbial
growth and to prolong the storage time of coffee. To this date, mechanical drying methods have been developed and employed
in industries to shorten the drying time. However, these drying methods could alter the physicochemical properties of coffee
and the compounds present in coffee. Therefore, it is crucial to maintain these factors in the coffee production process as they
affect the stability, reconstitution, and aroma of the coffee produced. These properties are crucial as they determine the final
quality of coffee. This review will focus on the effect of spray-drying, freeze-drying, and spray-freeze–drying on the phys-
icochemical properties of coffee such as morphology, particle size, moisture content, bulk density, and compound retention.
Effects on organoleptic properties are also discussed. Possible advancements to these drying methods such as the encapsulation
process, the use of a porous frozen sample, and total solid enhancement of the raw material have been highlighted.
Keywords Coffee-drying· Spray-drying· Freeze-drying· Physicochemical
Introduction
Coffee is one of the crop commodities with a relatively high
economic value (Marhaenanto etal., 2015). In May 2021, all
the coffee exporting countries shipped a total of 9.8 million
60-kg bags of coffee beans worldwide (ICO, 2021). Among
over 100 species of the Coffea genus, however, Coffea arabica
(arabica) and Coffea canephora (robusta) are the most
economically important coffee species since both species
are commercially cultivated and traded (Ameyu, 2016; Dias
& Benassi, 2015; Farhaty & Muchtaridi, 2014; ICO, 2021).
The authors added that arabica coffee beans produce high-
quality coffee due to their superior aroma and flavor that affect
organoleptic properties, as opposed to robusta coffee beans
which have lower commercial value and sensory quality.
As one of the most consumed beverages globally, coffee
is on-demand because it has a unique aroma and distinct
flavor due to the complexity of its compound. Research has
so far revealed around 1000 volatile compounds present in
coffee, including aroma-active and non-aroma-active com-
pounds (Mahmud etal., 2020) Consuming coffee has been
associated with a healthy profile in consumers, reducing the
risk of disease development such as type 2 diabetes, depres-
sion, suicidal behavior, cancer, and giving positive effects
on the gastrointestinal tract and gut microbiota (de Melo
Pereira etal., 2020). Besides, coffee also increases alertness
(Purdiani, 2014).
The manufacturing processes of instant coffee powder
start with the roasting of green coffee beans, followed by a
grinding process (Huang & Zhang, 2013). The ground cof-
fee beans produced are then extracted to get their aroma and
flavor compounds. After that, the coffee extract is dried to
produce a coffee extract powder aroma and flavor of the
coffee powder affecting the customer acceptance level. Cof-
fee flavor is arguably the most paramount aspect of good
quality coffee (Sunarharum etal., 2014). Coffee processing
becomes one of the factors affecting coffee flavor as shown
in Fig.1. As a result, choosing the proper coffee powder
process becomes necessary since the key compounds in
* Dian Shofinita
shofi1988@office.itb.ac.id
1 Department ofFood Engineering, Institut Teknologi
Bandung, Jl. Let. Jen. Purn. Dr. (HC), Mashudi No. 1/Jalan
Raya Jatinangor KM 2075, Sumedang45363Bandung,
Indonesia
2 Department ofChemical Engineering, Institut Teknologi
Bandung, Jl. Ganesa No. 10, Bandung40132, Indonesia
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Drying and post-processing treatments both impact the physicochemical properties of green coffee beans, such as density [8,9], moisture content [10,11], and water activity [12]. These factors contribute to multiple benefits, including weight and volume reduction, storage and transportation costs, handling systems, grading, hulling, aroma, flavor, and texture, as well as sensory attributes [6,7]. Biochemical compounds in coffee, including caffeine, trigonelline, chlorogenic acid, and caffeic acid, impact its flavor by imparting astringency, bitterness, and aromatic formations that contribute to acidity [13][14][15]. ...
... Biochemical compounds in coffee, including caffeine, trigonelline, chlorogenic acid, and caffeic acid, impact its flavor by imparting astringency, bitterness, and aromatic formations that contribute to acidity [13][14][15]. Coffee composition undergoes a slight change or remains stable throughout post-harvest processing because enzymatic and chemical processes are influenced by the drying conditions and duration [6,7,15]. The biochemical structure of Arabica is strongly affected by variety, growing environment, altitude, and processing [16,17]. ...
... The taste of the coffee is significantly affected by the sun-drying process, which depends on climatic conditions [5]. Several researchers investigated mechanical drying techniques in industrial settings to reduce drying time [6,7]. Shofinita et al. [6] reported that a high temperature during the drying process could lead to reduced storage time and structural damage; therefore, methods of coffee drying and the operating conditions should be carefully considered. ...
Influence of Post-Harvest Processing and Drying Techniques on Physicochemical Properties of Thai Arabica Coffee
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Coffee post-processing drying eliminates moisture content, reduces fungal and microbe growth, and develops unique aroma and flavor compounds. Thai coffee producers use controlled-environment drying (CED) techniques to improve the quality and cupping scores of the coffee. This research investigated how different drying methods, including sun drying (SD), controlled-environment drying at 20-30 °C, 50-55% RH, and fast drying (FD) at 30-45 °C influenced the physico-chemical characteristics of coffee undergoing dry (DP), washed (WP), and honey (HP) processing. Results showed that true density, moisture content, water activity, color, caffeine, trigonelline, chlorogenic acid, caffeic acid, sucrose, and fructose in green coffee beans were significantly affected (p < 0.05) by both drying technique and post-harvest processing. Drying techniques and processing directly impacted the characteristics of green (GCB) and roasted coffee beans (RCB). Findings suggested a correlation between CED, SD, and FD based on the physicochemical and biochemical properties and sugar contents of both green and roasted coffee beans.
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... Although traditional drying methods (including sun exposure and air circulation) are simple and easy to use, excessive drying time can lead to excessive loss of volatile components in the sample, affecting the sample flavor and this drying method is easily limited by environmental conditions [11,12]. Therefore, it is necessary to develop new drying methods to improve the drying quality of ginger slices. ...
... The results of the analysis were shown in Table 3. The ginger under different drying conditions contained a variety of substances, with 55 different types of VOCs identified and 18 peaks not identified, including alcohols (12), aldehydes (12), ketones (11), alkenes (11), esters (4), and others (5). The Gallery Plot plug-in in LAV software was used to quantitatively analyze the difference in VOCs in ginger that had undergone different drying methods, as shown in Figure 8b; each row represents a sample and each column represents a volatile component. ...
... The results of the analysis were shown in Table 3. The ginger under different drying conditions contained a variety of substances, with 55 different types of VOCs identified and 18 peaks not identified, including alcohols (12), aldehydes (12), ketones (11), alkenes (11), esters (4), and others (5). The Gallery Plot plug-in in LAV software was used to quantitatively analyze the difference in VOCs in ginger that had undergone different drying methods, as shown in Figure 8b; each row represents a sample and each column represents a volatile component. ...
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... Several compounds have effects on the organoleptic properties of coffee, such as chlorogenic acids (CGAs) [4], trigonelline, and caffeine. CGAs gives bitterness, sour and astringency, aroma formation, and has a role in coffee pigmentation post-roasting [5,6], while trigonelline has a role in volatile compound formation during roasting, producing aroma compounds like pyridines, pyrroles, and pyrazine, which contributes to 24 % of total volatile compounds [7]. But the main bioactive compound desirable in coffee is caffeine, which is the alkaloid compound giving coffee its characteristic bitterness, astringency, and aftertaste [8]. ...
... Some even preferred the flavor of decaffeinated coffee over the non-decaffeinated one [60]. In terms of aroma, decaffeinated coffee does not differ significantly from non-decaffeinated coffee, although regular coffee mainly possesses pyrazine-derived compounds while decaffeinated coffee tends towards furan-derived compounds [7,31,60,63,104]. ...
Effects of different decaffeination methods on caffeine contents, physicochemical, and sensory properties of coffee
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Coffee consumption could provide various benefits for human health, but also could contribute to several health problems. The growing trend of coffee consumption has created a rising demand for decaffeinated coffee that is safe for consumers with low caffeine tolerance. Decaffeination process, however, can result in the alteration of several properties of coffee which affect overall coffee taste. This review discussed current decaffeination methods such as water decaffeination, solvent decaffeination, supercritical decaffeination, and biodecaffeination which includes their mechanisms, benefits, and drawbacks as well as their effect in the physicochemical and sensory characteristics of coffee. Solvent decaffeination has showed potential improvements in the future such as the incorporation of membrane and ultrasonic technology. In addition, the mathematical model for caffeine diffusion has been arranged according to Fick’s second law of diffusion, based upon spherical and rectangular coordinates with several assumptions. Further research should be aimed to maintain the properties of coffee after decaffeination process. Furthermore, utilizing new solvents that are safe and non-toxic will potentially be favorable research in the development of decaffeination methods in the future.
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... Coffee producers are encouraged to adopt cutting-edge dehydration methods and processing technology to streamline operations, ensure consistent quality, reduce waste, and meet consumer demands. Furthermore, advancements in these areas can contribute to improved sustainability standards within the coffee industry by reducing energy, water usage, and environmental impact, including greenhouse gas emissions [7]. ...
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This comprehensive study delves into advanced dehydration techniques and processing technologies in the realm of coffee manufacturing. It offers a comparative analysis of these techniques, specifically focusing on green coffee beans and instant coffee production. The examination encompasses the pivotal steps of grading, roasting, grinding, extraction, and dehydration, which form the core of the coffee manufacturing process. In the context of instant coffee production, two primary dehydration methods, spray-drying and freeze-drying, are scrutinized for their roles in water removal from coffee extracts and slurries and their impact on final product quality and efficiency. This study emphasizes the significance of dehydration processes as the linchpin of manufacturing optimization, considering their prominence in coffee production plants. Furthermore, the research extends to investigate the diverse extraction techniques, additional processes, and critical technologies, such as agglomeration, used in the production of coffee instant powder. Quality control, life cycle analysis, and assurance are scrutinized to provide insights into the overall sustainability of coffee manufacturing. The examination also explores the environmental impact, byproducts, and nuanced properties of coffee powder across different production systems. In essence, this review serves as a valuable resource for industry professionals, researchers, and coffee enthusiasts, offering a holistic understanding of advanced coffee dehydration techniques and their impact on quality, efficiency, and sustainability in the context of both green coffee beans and instant coffee production.
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... FSE also presented a significant caffeine content of 1.91 %. This is a very relevant value comparable to that of dry coffee extracts, in which this compound ranged from 1.50 to 3.98 % (Shofinita et al., 2023). Caffeine is known to stimulate the central nervous system and to improve cognitive and physical performance. ...
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Prebiotic demand is increasing due to growing concerns about human gut health and well-being. Recently, agri-food by-products have been explored as a potential source of prebiotic ingredients. This study analysed the chemical composition of a freeze-dried coffee silverskin extract (FSE) and evaluated its impact on Lacticaseibacillus paracasei subsp. paracasei BAA-52 ATCC growth. The FSE was obtained by multi-frequency multimode modulation ultrasonic vibration. Soluble dietary fiber accounted for 15.2 % of the extract, being mainly composed of uronic acids (58 mol%) and glucose (13.4 mol%). HPLC-DAD-MS-ESI+ and HPLD-DAD analyses revealed a phenolic-rich composition (mainly caffeoylquinic acids), as well as the presence of caffeine, and 5-hydroxymethylfurfural. The probiotic was incubated in De Man, Rogosa, and Sharpe broth supplemented with different concentrations of the FSE (1–4 %, w/v). The 2 % and 4 % (w/v) concentrations significantly enhanced L. paracasei subs. paracasei growth and decreased the pH of the medium, indicating its potential as a prebiotic ingredient.
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... Drying processes for commercial instant coffee usually reduce its water content by less than 5% by mass. The remaining composition of the blend is a mixture of carbohydrates, proteins, flavor oils, phosphates, and melanoidins (Gloess et al., 2013;Khan et al., 2021;Shofinita et al., 2024). ...
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Background Coffee is one of the beverages consumed the most worldwide since ancient times. Previously, coffee used to be consumed due to its stimulating effect stemming from caffeine and its distinctive taste. In recent years, it has gone beyond being just a hot drink containing stimulating agents and has started to be consumed with the awareness about its positive effects on health. The compounds of coffee bearing antioxidant potential can be listed as caffeine, chlorogenic acids, caffeic acid, coumaric acid, nicotinic acid, ferulic acid, trigonelline, cafestol, and kahweol. Scope and approach While it is reported that coffee impacts a range of chronic diseases including obesity, cancer, neurodegenerative and cardiovascular diseases due to the caffeine, chlorogenic acids, and diterpenoid alcohol it contains and that further research is needed in this respect, coffee is also related to a reduced risk of autoimmune diseases. This review aims to elaborate on the relationship between coffee consumption and the immune system. Key findings and conclusions In addition, it has been highlighted in recent years that the above-mentioned compounds of coffee stimulate the immune system thanks to their antioxidant and anti-inflammatory effects. The positive effects of coffee on the immune system stem from caffeine, chlorogenic acids, kahweol, cafestol and similar compounds it contains. Particularly caffeine and polyphenols are considered as the main agents nourishing coffee with immunomodulatory characteristics depending on the daily dose of consumption.
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