Does beer spoil or “skunk” if it warms up and is cooled again?

By Dr Jorge Metri (PhD) | Reviewed by Dr Anny Manrich (PhD)
Page last updated: 01/07/2023 | Next review date: 01/07/2025
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The contents of this article are fact-based except otherwise stated within the article.

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Author bio

Dr Jorge Metri PhD is a Nutritionist with vast experience in food design with natural ingredients. He also researches sensory sciences and food quality with cutting-edge technologies like Machine Learning. He writes and reviews content on these topics.

Dr Jorge Metri’s highlights:

  • Invited Reviewer of two international scientific Journals
  • PhD in Food Science with emphasis on reduced-fat salad dressings with non-animal derived proteins at Universidad De Las Américas Puebla
  • Diploma in Artificial Intelligence at Universidad Anáhuac, México
  • Bachelor’s degree in Nutrition at the Universidad Latino

“Science shows its true impact when we make it understandable for everyone” – Dr Jorge Metri PhD.

Professional experience:

Prior to doing his PhD, Jorge Metri worked as an independent nutritionist for almost two years, focusing on sports nutrition to enhance the performance of swimmers and triathletes.

Jorge Metri has worked on several multidisciplinary research projects, including fruit processing, the production of protein-based products, spices, seasonings, jams, and artificial intelligence applied to agriculture production and food quality.

In the food technology area, Jorge Metri has contributed to improving sales and profits of two entrepreneurs of artisanal food products by reformulating their products and standardizing their processes.

Due to the high volume of food production and innovation, the food industry will need new technologies for food characterization in the next years; Jorge Metri is looking for studying such technologies, in 2022, he was selected as a finalist in the IFT FIRST 2022 Food Science event for the Sensory & Consumer Sciences Division Graduate Student Pangborn Oral Competition with the work titled: Machine Learning Models for Mayonnaise Acceptability Prediction.

Education:

  • 2018 – 2023: PhD in Food Science at Universidad De Las Américas Puebla of Puebla, México
  • 2022: Diploma in Artificial Intelligence at Universidad Anáhuac, México
  • 2011 – 2016: Bachelor’s degree in Nutrition at the Universidad Latino of Mérida Yucatán, México.

Main publications of Jorge Metri:

Conference papers:

You can view some of Dr Metri’s work below and links to his professional profiles:

LinkedIn: https://www.linkedin.com/in/jorge-metri-ojeda/ 

Research Gate:  https://www.researchgate.net/profile/Jorge-Carlos-Metri-Ojeda-2 

Google Scholar: https://scholar.google.com/citations?user=SBi5hE8AAAAJ&hl=es 

ORCID: https://orcid.org/0000-0002-7333-3688 


Dr Jorge Metri (PhD)
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Reviewer bio

Dr Anny Manrich PhD is a food Engineer with expertise in Food Technology, Natural Polymers, Edible Films, Enzymes, and Nanotechnology. She writes and reviews content on these topics.

Dr Anny Manrich’s Highlights: 

  • Research and Technology at the Brazilian Agricultural Research Corporation
  • PhD in Chemical Engineering with a focus on Biochemistry at the Federal University of Sao Carlos/ Brazil and a one-year scholarship at the Technical University of Munich/ Germany
  • Bachelor of Food Engineering at the University of Campinas/ Brazil and a one-year scholarship at the Technical University of Munich/ Germany

 

“To solve a problem, global vision and multifactorial understanding are necessary. Therefore, in addition to expertise, one should seek multidisciplinary thinking connected with science and reality” – Dr Anny Manrich, PhD.

Professional Experience: 

Dr Anny Manrich’s Experience Joining the Brazilian Agricultural Research Corporation, as soon as she completed her doctorate, 

 

Dr Anny Manrich has worked on several projects, including the more than three-year partnership project with BRF, a major food producer in Brazil. As a postdoctoral fellow. 

 

Dr Anny Manrich has also contributed to several business consultancies and research projects of the National Nanotechnology Laboratory System in areas such as food technology, fibres, films and coatings and Nanotechnology; in a very determined way, having a great team relationship, being creative and committed. 

Growing concerns about the safe introduction of nanomaterials into today’s life emphasises the need to create regulatory documentation in front of characterising, using and testing them. Dr Anny Manrich worked for two years on a characterization project for nanoscale materials, with the aim of exploring their possible health effects.

 

Despite not having specific academic training in packaging or polymeric films, Dr Anny Manrich works at the Brazilian Agricultural Research Corporation in areas of edible and biodegradable films produced from agricultural waste and in the development of films with greater resistance to water, having articles published in renowned scientific journals, which demonstrates her multidisciplinary understanding and creativity. 

 

In addition, she worked for four years as a consultant to a food company to develop a line of snacks that are healthy and that add functional ingredients, physiologically active compounds that bring health benefits, made from fruits and vegetables, enabling diet improvement, disease prevention and reduction of nutritional deficiencies. 

Dr Anny Manrich participated as a member of the examination board for two Master’s exams and one PhD exam at the Department of Chemical Engineering of the Federal University of São Carlos.

Education:

  • 2001 Bachelor in Food Engineering at the State University of Campinas, Brazil
  • 1999 One year scholarship at the Technical University of Munich
  • 2004 Master in Chemical Engineering at the Federal University of São Carlos, Brazil
  • 2012 PhD in Chemical Engineering at the Federal University of São Carlos, Brazil
  • 2010 One year scholarship at the Technical University of Munich

The main publications of Dr. Anny Manrich are:

Articles

Manrich, A., Moreira, F. K., Otoni, C. G., Lorevice, M. V., Martins, M. A., & Mattoso, L. H. (2017). Hydrophobic edible films made up of tomato cutin and pectin. Carbohydrate Polymers, 164, 83-91.

Mendes, J. F., Norcino, L. B., Martins, H. H. A., Manrich, A., Otoni, C. G., Carvalho, E. E. N., … & Mattoso, L. H. C. (2020). Correlating emulsion characteristics with the properties of active starch films loaded with lemongrass essential oil. Food Hydrocolloids, 100, 105428.

Norcino, L. B., Mendes, J. F., Natarelli, C. V. L., Manrich, A., Oliveira, J. E., & Mattoso, L. H. C. (2020). Pectin films loaded with copaiba oil nanoemulsions for potential use as bio-based active packaging. Food Hydrocolloids, 106, 105862.

Manrich, Anny, et al. Immobilization of trypsin on chitosan gels: Use of different activation protocols and comparison with other supports. International Journal of Biological Macromolecules 43.1 (2008): 54-61.

Manrich, Anny; Komesu, Andrea ; Adriano, Wellington Sabino; Tardioli, Paulo Waldir ; Giordano, Raquel Lima Camargo . Immobilization and Stabilization of Xylanase by Multipoint Covalent Attachment on Agarose and on Chitosan Supports. Applied Biochemistry and Biotechnology, v. 161, p. 455-467, 2010.

Mendes, J. F., Martins, J. T., Manrich, A., Neto, A. S., Pinheiro, A. C. M., Mattoso, L. H. C., & Martins, M. A. (2019). Development and physical-chemical properties of pectin film reinforced with spent coffee grounds by continuous casting. Carbohydrate polymers, 210, 92-99..

Milessi, T. S., Kopp, W., Rojas, M. J., Manrich, A., Baptista-Neto, A., Tardioli, P. W., … & Giordano, R. L. (2016). Immobilization and stabilization of an endoxylanase from Bacillus subtilis (XynA) for xylooligosaccharides (XOs) production. Catalysis Today, 259, 130-139.

Mendes, J. F., Norcino, L. B., Manrich, A., Pinheiro, A. C. M., Oliveira, J. E., & Mattoso, L. H. C. (2020). Development, physical‐chemical properties, and photodegradation of pectin film reinforced with malt bagasse fibers by continuous casting. Journal of Applied Polymer Science, 137(39), 49178.

Mendes, J. F., Martins, J. T., Manrich, A., Luchesi, B. R., Dantas, A. P. S., Vanderlei, R. M., … & Martins, M. A. (2021). Thermo-physical and mechanical characteristics of composites based on high-density polyethylene (HDPE) e spent coffee grounds (SCG). Journal of Polymers and the Environment, 29, 2888-2900..

Mendes, J. F., Norcino, L. B., Martins, H. H., Manrich, A., Otoni, C. G., Carvalho, E. E. N., … & Mattoso, L. H. C. (2021). Development of quaternary nanocomposites made up of cassava starch, cocoa butter, lemongrass essential oil nanoemulsion, and brewery spent grain fibers. Journal of Food Science, 86(5), 1979-1996.

Manrich, A., Martins, M. A., & Mattoso, L. H. C. (2021). Manufacture and performance of peanut skin cellulose nanocrystals. Scientia Agricola, 79.

Nascimento, V. M., Manrich, A., Tardioli, P. W., de Campos Giordano, R., de Moraes Rocha, G. J., & Giordano, R. D. L. C. (2016). Alkaline pretreatment for practicable production of ethanol and xylooligosaccharides. Bioethanol, 2(1)..

Manrich, Anny, de Oliveira, J. E., Martins, M. A., & Mattoso, L. H. C. Physicochemical and Thermal Characterization of the Spirulina platensis. J. Agric. Sci. Technol. B, v. 10, p. 298-307, 2020.

 

Book Chapter

Terra, I. A. A., Aoki, P. H., Delezuk, J. A. D. M., Martins, M. A., Manrich, A., Silva, M. J., … & Miranda, P. B. (2022). Técnicas de Caracterização de Polímeros. Nanotecnologia Aplicada a Polímeros, 614.

 

Conference Papers

Ferreira, L. F., Luvizaro, L. B., Manrich, A., Martins, M. A., Júnior, M. G., & Dias, M. V. (2017). Comparação da estabilidade de suspensões poliméricas de amido/tocoferol e quitosana/tocoferol. In: CONGRESSO BRASILEIRO DE POLÍMEROS, 14., 2017, Águas de Lindóia, SP.

Manrich, A., Hubinger, S. Z., & Paris, E. C. (2017). Citotoxicidade causada por nanomateriais: avaliação do micronúcleo. In: WORKSHOP DA REDE DE NANOTECNOLOGIA APLICADA AO AGRONEGÓCIO, 9., 2017, São Carlos. Anais… São Carlos: Embrapa Instrumentação, 2017. p. 655-658. 

Manrich, Anny, et al. Immobilization and Stabilization of Xylanase by multipoint covalent attachment on Glyoxyl Agarose Support. The 31st Symposium on Biotechnology for Fuels and Chemicals. 2009.

 

Manrich, Anny, et al. Application of immobilized xylanase on hydrolysis of soluble wood hemicelluloses after using microwave and organosolv pre-treatments. The 32nd Symposium on Biotechnology for Fuels and Chemicals. 2010.

 

You can view some of Dr Anny’s work below and links to her professional profile. 

 

Research Gate: https://www.researchgate.net/profile/Anny-Manrich-2  

 

Scopus: https://www.scopus.com/authid/detail.uri?authorId=23103497100  

 

Google Scholar: https://scholar.google.com/citations?hl=en&user=Ea9qpr0AAAAJ  

 

Linkedin: https://br.linkedin.com/in/anny-manrich-20693129

 


Dr Anny Manrich (PhD)
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In this brief article, we will address the query “Does beer spoil or “skunk” if it warms up and is cooled again?” We will explore the factors that affect beer spoilage and what happens if you warm up a chilled beer. Finally, we present brief tips on how to store your beers to avoid quality issues.

Does beer spoil or “skunk” if it warms up and is cooled again?

No, beer does not get spoiled by warming and cooling cycles. The “skunk” phenomenon is a flavor and aroma related quality defect due to oxidation (1).

Oxidation of beer can be caused by storing beer in a colorless bottle. Beer contains a lot of molecules sensitive to sunlight, so using a colorless bottle will favor the photooxidation of beer’s components (1).

What characterizes the “skunk” in beer?

The “skunk” off-flavor is described as moldy, cabbagey, cardboardy, and sour flavors, this flavor profile is caused by the decomposition of iso alpha acids in beer (2,3). 

Iso alpha acids are contained in the hops used during beer production, they are responsible for bitterness, aroma, and some astringent sensations in beer; however, they are very sensitive to light (3).

When iso alpha acids are decomposed by light, they turn into 3-methylbut-2-ene-1-thiol, a chemical compound that provides the stale and skunk flavor (3). 

The 3-methylbut-2-ene-1-thiol is a very potent flavor, a beer needs around 4 ng/L (around 0.000001 mg per liter of beer) for you to notice the skunk flavor (2).

On the other hand, other factors like temperature and vibrations can affect the flavor of beer (usually caused during transportation); in this case, storing beers at high temperatures (>45 °C) can cause the conversion of alcohol to aldehydes, which in high concentrations, can produce aging flavors and even staling off-odors (3,4).

What are the Factors Affecting Beer Spoilage?

There are several factors influencing beer spoilage, they can be categorized in biological and non-biological factors (2). 

The biological spoilage of beer is caused by bad hygiene or contamination with bacteria or yeast that causes further metabolic changes in beer (2). 

Lactic acid bacteria, fungi, and acetic acid bacteria are the main microorganisms that cause beer spoilage, they can create different acids like lactic or acetic acids, or even produce toxins like mycotoxins (in the case of fungi) (2).

The common non-biological factors that affects beer quality are (2): 

  • Turbidity due to insufficient filtration (but some beer types are turbid).
  • Bitterness or taste alteration by conditions at any processing point: mashing, boiling, filtering, hops addition, fermentation.
  • Skunk flavor due to photooxidation. 
  • Weak or too persistent foam due to low or high protein content, respectively.

Are There any Quality Defects by Warming up and Cooling Beer Again?

Yes, if beer is chilled and warmed again, then it is stored at room temperature for long time periods, the beer can get hazy. The haze caused by warming up chilled beers is caused by complexes between proteins and polyphenols contained in beers (3).

Hazy beers are not spoiled per se, you can consume it because there is no flavor or aroma changes. Probably hazy beers will not get a strong foam, because foam is dependent on proteins (3).

What are the Best Storage Practices for Beer?

The best storage practices for beer are using opaque bottles and keeping it at a constant temperature (room temperature or cooled) (2,3). 

The opaque bottles can be green, brown, or black, the opaqueness will reduce the exposure of beer to sunlight, and it will prevent the skunk phenomenon (2,3).

In the case that your beers are in a colorless bottle, keep them in a dark place to avoid their exposure to sunlight. Keeping your beers in a dark place will prevent skunk phenomenon (2,3).

If your beers are already chilled, maybe the best option is keeping them in the refrigerator to avoid haze. However, if you do not have problems with a hazy beer, you can warm it to room temperature (2,3).

Conclusion

In this brief article, we addressed the query “Does beer spoil or “skunk” if it warms up and is cooled again?” We explored the factors that affect beer spoilage and what happens if you warm up a chilled beer. Finally, we presented brief tips on how to store your beers to avoid quality issues.

References

  1. Habschied K, Košir IJ, Krstanović V, Kumrić G, Mastanjević K. Beer polyphenols—bitterness, astringency, and off-flavors. Beverages, 2021;7(2):38.
  1. Stewart GG. Beer shelf life and stability. In: Subramaniam P, editor. The Stability and Shelf Life of Food. Elsevier; 2016. p. 293–309.
  1. Aguiar D, Pereira AC, Marques JC. The influence of transport and storage conditions on beer stability—a systematic review. Food Bioproc Tech, 2022;15(7):1477–94.
  1. Paternoster A, Jaskula-Goiris B, De Causmaecker B, Vanlanduit S, Springael J, Braet J, et al. The interaction effect between vibrations and temperature simulating truck transport on the flavor stability of beer. J Sci Food Agric, 2019;99(5):2165–74.

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