Course:FNH200/Projects/2021/Instant Coffee

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Nescafe instant coffee in an hourglass packaging taken by TahiraNaroth

Introduction

Instant coffee or soluble coffee is defined by the Government of Canada's Canadian General Standards Board as a "dried, water soluble powder obtained exclusively from roasted coffee". [1] Detailed requirements of instant coffee as outlined by the Food and Drug Regulations of Canada detail that instant coffee needs to dissolve in boiling water within 30 seconds, the moisture content cannot surpass 4.25% when agglomerated or 2.5% when it is not agglomerated, the caffeine content should be the same as normally brewed coffee, and caffeine can not be added or removed from regular instant coffee. [1]

Making

Just like with regular coffee, green coffee beans get turned into the aromatic brown beans that we purchase in our favorite stores or cafés via roasting. The roasting of the beans is a very important step, since specific properties such as flavors, aromas, and color are developed and affect the overall experience of the coffee as a consequence[2]. Several events that occur during roasting such as the transformation of polyphenolic constituents into a complex mixture of Maillard reactions products, as well as the formation of organic compounds resulting from pyrolysis, makes drastic changes to the chemical composition of the coffee[3]. After the roasting, coffee beans are cooled in order to stop the exothermic reactions and to prevent over-roasting, which might jeopardize the quality of the coffee. After cooling the roasted beans, they are ground, usually by multi-stage grinders. Some roasted beans end up being sold whole. Finally, the ground coffee is vacuum sealed and shipped.

Coffee Bean Roastertaken by Visitor7
Instant coffee dissolving in water taken by Northamerica1000

If the objective is producing instant coffee, another step of extraction is due after the roasting and grinding operations. The soluble solids and volatile compounds that provide the signature aroma and flavor of coffee are extracted from the coffee beans using water. Water heated to about 175 °C under pressurized conditions in-order to maintain the water as liquid, it is then used to extract all of the necessary solubles from the coffee beans. Manufacturers use both batch and continuous extractors. After extraction is done, evaporation or freeze concentration is used to increase the solubles’ concentration of the extract[4]. The concentrated extracts are then dried; freeze drying and spray drying being the most frequently used methods to produce instant coffee. Evaluations of different brands of instant coffee shows that the quality of coffee is associated with the quality of beans, variety in storage time, choice of fermentation process, roasting process, extraction of the soluble solids, and the packaging material. There are many different coffee brewing methods in the world. The most popular coffee brew preparation is by filter, but for the past few decades the consumption of espresso coffee has increased. Furthermore, in southern European countries such as Italy and Spain, the use of the moka coffee maker is much extended at the domestic level, and the plunger coffee maker is being used more often for coffee aroma lovers[5]. In each case, the technical conditions applied, such as the coffee/water ratio, water temperature and pressure, the volume of coffee prepared, and the home and store grinding, all contribute to the different chemical compositions of coffee brews[6].

Processing

Instant coffee granules inside glass cubetaken by SAM31416

After the coffee is brewed, the concentrated extracts are processed by either freeze drying or spray drying[7].

After drying, the instant coffee is packed in bulk or retail quantities[8]. The type of packaging used is discussed in further detail in the section dedicated to packaging.  

Freeze Drying

Using the freeze drying method, the coffee extract is frozen in a freezer cooled to -40 degrees Celsius and broken up into granules[7]. The granules are then sifted to create uniformity and freeze dried for 5 hours[7]. In the freeze drying process, the frozen granules are heated to 60 degrees Celsius using radiant heaters while a vacuum is maintained[7]. Sublimation occurs and water vapor is removed from the granules without the coffee being turned liquid again and the granules retain its shape[7]. This ensures coffee aromas will not be lost[7].

Spray Drying

Alternatively, in the spray drying method, concentrated coffee is pumped and sprayed using an atomizer into fine droplets into a chamber with hot, dry air that is between 200 to 300 degrees Celsius[7]. The water evaporates due to the hot air. The dried coffee granules are then collected at the bottom of the spray dryer as the moist air is rerouted out of the machine[7]. A higher temperature creates higher quality powder, but if the temperature is too high, the powder will degrade[7]. Spray drying coffee creates a very fine powdery dust that is processed in an additional step called agglomeration[9]. The dust-like instant coffee is processed in a roasting drum where it is slightly rehydrated using an agglomerating fluid, which is a concentrated aqueous coffee solution[9]. The solution increases the moisture content of the instant coffee, which causes the particles to stick together and form larger granules[9]. This improves the solubility of instant coffee in water[9].

Lost aromatic compounds will sometimes be added back into spray dried instant coffee[10]. Before percolation, the coffee aroma is combined with steam and concentrated. This aromatic gas can then be sprayed onto the instant coffee to recover the lost aroma[10]. Alternatively, the instant coffee can be placed with roasted coffee so the instant coffee absorbs the aroma of the roasted coffee[10].

Spray Drying vs. Freeze Drying

Due to the high temperatures necessary when coffee is spray dried, some of the aromatic compounds are lost in comparison to freeze drying. Freeze drying is expensive because it requires cold temperatures and low pressure to be maintained. However, when freeze dried instant coffee is considered to be higher quality due to the flavour and aroma[11]. Overall, the entire process of freeze drying is more energy intensive, costly, and takes longer than spray drying[11]. Laboratory testing of antioxidant activity showed that spray dried coffee has higher levels of antioxidant activity than freeze dried coffee[12].

Aroma

A coffee's aroma is created by its volatile components that come in contact with the olfactory membranes in three different time-intensity profiles. The first burst has high volatility, which is released directly into the gas phase without getting dissolved. The “burst” of aroma peaks at around 20 sec then decrease rapidly[13]. The second set of compounds were present in the initial bursts but then remained stable. These are the “core” of aroma. Finally, the “mature” aroma increases over the entire 5 min and lasts for a long time[13]. Since the aroma is the release of flavorful compounds from coffee into the air, fresh instant coffee obtains a stronger aroma than old instant coffee. A higher temperature of processing leads to more aroma loss. Generally the higher quality of bean with a lower temperature during processing create a better final taste and aroma (i.e. flavour) of the instant coffee[13].

Packaging

Instant coffee in tin cans taken by Alfvanbeem

Various packaging are used to extend the shelf life of instant coffee while retaining its quality. Modified atmosphere packaging uses nitrogen gas to flush and displace oxygen in the coffee bag before filling it [14]. This inhibits the growth of spoilage-causing and disease-causing microorganisms. Moisture and oxygen barriers of packaging are critical for preserving the quality of instant coffee. For instance, tin, plastic and glass containers have a large headspace volume, which will be filled with air once open, resulting in a high level of moisture and oxygen absorption[15]. Lowering the amount of oxygen in contact with the coffee powder is the determining factor in reducing the rate of oxidation during storage, which is also discussed in the customer preference section below. Triplex bags, in comparison, are less rigid. Its flexibility allows consumers to reshape triplex bags reducing the surface-to-

Instant coffee in a triplex bag taken by Tifb

volume ratio while using. A smaller surface area of the powder will be exposed to the headspace air. This makes triplex bags a more suitable packaging material for instant coffee based on moisture and oxygen intake[15]. Equally important, protection against heat and light preserves the quality of instant coffee. Both heat and light will increase the speed of undesirable chemical reactions that might occur during storage. Triplex bags, made of aluminum, and tin cans both provide an absolute light barrier and high heat barrier[14]. Whereas plastic and glass containers allow light to penetrate through, but acquire the advantage of seeing the products inside. As a result, triplex bags provide better quality protection during long-term storage than rigid plastic, tin and glass containers, while plastic and glass have the advantage of seeing through the container.

Customer Preference for Aesthetics

On top of packaging for the best processing and storage, it is important to take into account customers preferences. In order for customers to experience the problems of storage and processing they must be first bought. Marcela Lika Kobayashi recruited five focus group sessions to discuss their opinions on packaging[16]. Interestingly enough many customers' preferences of instant coffee interfere with the best packaging methods meaning that many coffee makers must weigh the options of customers preferences and what is best for the coffee itself. Benković et al.’s[15] paper found that triplex bags that have layers of aluminum and tin were better for preserving the instant coffee in both the metrics of moisture and oxygen barriers and in stopping light and heat. This is the opposite of what consumers of Kobayashi’s study stated that they rather glass jars that were square or hourglass shaped[16]. This is the opposite of what Benković et al’s paper suggested due to the lack of transparency, higher surface area to be affected by the light and greater likelihood for moisture and oxygen to leak through. Though brand loyalty will aid some companies to retain customers but it has been demonstrated that it will dissipate once there are undesired characteristics [16]. Customers liked to see dark and granulated coffee to be present in transparent packaging. Bright colours, especially gold, red and brown were preferred. A way that companies may be able to attract customers with suboptimal packaging is by using the preferred labelling. Bright background colors with pictures of coffee cups with steam were rated positively by the groups. The brought colours allowed for contrasts for clearly listed labels and preparation instructions[16].

Health Effects

Even though instant coffee is more processes than brewed coffee, there are still many benefits. A study done by Tena Niseto et al. in 2012 [17]showed that certain antioxidant levels might be higher in instant coffee than in brewed, possibly due to the processing methods. It also contains less caffeine than regular coffee with 30-90 mg of caffeine compared to 70-140 mg respectively, beneficial for people who wish to cut back of their caffeine levels [18]. The one downside of coffee is that Hanna Mojska and Iwona Gielecińska in 2013[19] found that instant coffee contains up to twice as much acrylamide, a potentially harmful chemical that may cause nervous system damage and increased risk of cancer. That said, the amount of acrylamide in coffee is much lower than harmful levels so the risks are low[18].

Exam Question

Question: There are 2 methods creating instant coffee, which one results in higher quality instant coffee?

Options: (choose one)

A. Drum drying

B. freeze drying

C. spray drying

D. tray drying

E. sun drying.

Answer: B. The two methods of freeze drying and spray drying are mainly used to create instant coffee. Due to the ability to create granules that can be easily dissolved in water. Freeze drying results in more high quality coffee because the temperature is lower than that of spray drying. A higher temperature of processing leads to more aroma loss.




We expect our fellow students to know this, because it is a form of drying which we learned about in Module 8.

  1. ↑ 1.0 1.1 Canada. (2014) Instant coffee Canadian General Standards Board.
  2. ↑ Hernández, J., Heyd, B., & Trystram, G. (2008). "On-line assessment of brightness and surface kinetics during coffee roasting." Journal of Food Engineering, 87(3), 314–322. https://doi.org/10.1016/j.jfoodeng.2007.12.009
  3. ↑ Solange I. Mussatto & Ercília M. S. Machado & Silvia Martins & José A. Teixeira (16 March 2011). "Production, Composition, and Application of Coffee and Its Industrial Residues" (PDF). Food Bioprocess Technol (2011) – via Springer Science+Business Media, LLC 2011. line feed character in |title= at position 51 (help)
  4. ↑ EPA (13 May 2010). "Coffee" (PDF). United States Environmental Protection Agency.
  5. ↑ Pérez-Martínez, M., Caemmerer, B., De Peña, M. P., Cid, C., & Kroh, L. W. (2010). "Influence of brewing method and acidity regulators on the antioxidant capacity of coffee brews." Journal of agricultural and food chemistry, 58(5), 2958–2965. https://doi.org/10.1021/jf9037375
  6. ↑ Andueza, S., Maeztu, L., Pascual, L., Ibanez, C., de Peña, M. P., & Cid, C. (2003). "Influence of extraction temperature on the final quality of espresso coffee". Journal of the Science of Food and Agriculture. line feed character in |title= at position 49 (help)CS1 maint: multiple names: authors list (link)https://doi.org/10.1002/jsfa.1304
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 Mussatto, S. I., Machado, E. M. S., Martins, S., & Teixeira, J. A. (2011). "Production, Composition, and Application of Coffee and Its Industrial Residues." Food and Bioprocess Technology, 4(5), 661–672. https://doi.org/10.1007/s11947-011-0565-z
  8. ↑ GEA solutions for instant coffee production. (2021)." GEA Engineering for a Better World. "https://www.gea.com/en/solutions/instant-coffee-plant.jsp
  9. ↑ 9.0 9.1 9.2 9.3 US 3615669, Hair, Eddy; Cody, Robert; Mclain, Aubrey “Process for Agglomerating Instant Coffee”, issued 1971.
  10. ↑ 10.0 10.1 10.2 Food Tech Notes (August 30, 2020). “Instant Coffee Manufacturing Process”. Retrieved 9 August 2021.
  11. ↑ 11.0 11.1 Padma Ishwarya, S., & Anandharamakrishnan, C. (2015). "Spray-Freeze-Drying approach for soluble coffee processing and its effect on quality characteristics." Journal of Food Engineering, 149, 171–180. https://doi.org/10.1016/j.jfoodeng.2014.10.011
  12. ↑ Ghirişan, A., & Miclăuş, V. (2017). "Comparative study of spray-drying and freeze drying on the soluble coffee properties." Studia Universitatis Babeș-Bolyai Chemia, 62(4), 309–316. https://doi.org/10.24193/subbchem.2017.4.26
  13. ↑ 13.0 13.1 13.2 Zanin, R. C., Smrke, S., Kurozawa, L. E., Yamashita, F., & Yeretzian, C. (2020). "Novel experimental approach to study aroma release upon reconstitution of instant coffee products." Food Chemistry, 317, 1-9. https://doi.org/10.1016/j.foodchem.2020.126455
  14. ↑ 14.0 14.1 Ohl, D. (2021, June 9). 4 "Factors to consider when Selecting Coffee Packaging." Viking Masek.https://vikingmasek.com/packaging-machine-resources/packaging-machine-blog/4-factors-to-consider-when-selecting-coffee-packaging
  15. ↑ 15.0 15.1 15.2 Benković, M., Srečec, S., Špoljarić, I., Mršić, G., & Bauman, I. (2015). "Fortification of instant coffee beverages - influence of functional ingredients, packaging material and storage time on physical properties of newly formulated, enriched instant coffee powders." Journal of the science of food and agriculture, 95(13), 2607–2618. https://doi.org/10.1002/jsfa.6989
  16. ↑ 16.0 16.1 16.2 16.3 Kobayashi, M. L., & Benassi, M. D. T. (2015). "Impact of Packaging Characteristics on Consumer Purchase Intention: Instant Coffee in Refill Packs and Glass Jars." Journal of Sensory Studies, 30(3), 169–180. https://doi.org/10.1111/joss.12142
  17. ↑ Niseteo, T., Komes, D., Belščak-Cvitanović, A., Horžić, D., & Budeč, M. (2012). "Bioactive composition and antioxidant potential of different commonly consumed coffee brews affected by their preparation technique and milk addition." Food Chemistry, 134(4), 1870–1877. https://doi.org/10.1016/j.foodchem.2012.03.095
  18. ↑ 18.0 18.1 Bjarnadottir, A. (2019, October 08). Instant Coffee: Good or Bad? Retrieved from https://www.healthline.com/nutrition/instant-coffee-good-or-bad
  19. ↑ Mojska, H., & Gielecińska, I. (2013). "Studies of acrylamide level in coffee and coffee substitutes: influence of raw material and manufacturing conditions." Roczniki Panstwowego Zakladu Higieny, 64(3), 173–181.
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