Can dark chocolate go bad?

By Dr Tayse Ferreira F. Da Silveira PhD | Reviewed by Dr Tayse Ferreira F. Da Silveira PhD

Page last updated: 04/05/2023 | Next review date: 04/05/2025

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The contents of this article are fact-based except otherwise stated within the article.

Author bio

Dr Tayse has extensive experience in studying the chemical composition and stability of foods, as well as their bioactive properties.

Dr Tayse da Silveira´s Highlights:

Lecturer at the State University of São Paulo (Unesp), Brazil, for Food Engineering students
Post-doctorate in Food Science, with a one-year training period at Cirad – France.
PhD in Food Science, with a one-year scholarship at the University of Reading/United Kingdom.

Bachelor of Food Engineering at the Federal University of Pará, Brazil.

“Food Science is exciting because it touches our lives in such personal and intimate ways. Understanding food systems and gaining knowledge of how to manipulate them, helps society evolve as a whole” – Dr Tayse da Silveira.

Professional experience:

In her doctorate at the University of Campinas, Dr Tayse studied the effect of emergent preservation techniques, such as high-pressure processing, on the chemical and microbial properties of foods.

After completing her doctorate, Tayse da Silveira worked as a postdoctoral fellow in the Pharmaceutical Science Department at the University of São Paulo (USP), with a one-year training at CIRAD, Montpellier, France.

During this period, Dr Tayse worked on the development and evaluation of innovative antioxidant molecules for the preservation of fatty food products.

Dr Tayse also taught in public and private universities in Brazil for Nutrition, Food Engineering, and Enology students, always on food science and food technology-related subjects, including microbiology, milk technology, and wine-making technology.

She has also been involved in a number of studies evaluating the chemical composition and bioactive properties of food products, with emphasis on the development of analytical techniques to achieve that.

Currently, Dr Tayse works at the Centro de Investigação de Montanha (MRC), Portugal. She continues to work on the study of the chemical composition of foods, with a focus on identifying and isolating molecules with potential for application as food ingredients.

In her research, she targets molecules able to provide health and nutritional improvement, and antioxidant and antimicrobial properties (natural food additives).

She regularly publishes in high-impact, specialized scientific journals in her field, and feels encouraged to expand her knowledge domain by doing new scientific partnerships.

Education

2017 – PhD in Food Science at the University of Campinas Brazil, with a one-year training period at the University of Reading/United Kingdom.

2013 – Master’s Degree in Food Science at the University of Campinas, Brazil.

2011 – Bachelor of Food Engineering at the Federal University of Pará, Brazil.

Relevant Published work

Roschel GG, da Silveira TFF, Cajaíba LM, Ferrari RA, Castro IA. Combination of natural strategies to improve the oxidative stability of echium seed oil. Journal of Food Science. 2021;86(2):411-9.
de Moraes MR, da Silveira TFF, Coutinho JP, Souza DS, Duarte MCT, Duarte RT, et al. Bioactivity of atemoya fruits and by-products. Food Bioscience. 2021;41:101036.
Ferreira da Silveira TF, Laguerre M, Bourlieu-Lacanal C, Lecomte J, Durand E, Figueroa-Espinoza MC, et al. Impact of surfactant concentration and antioxidant mode of incorporation on the oxidative stability of oil-in-water nanoemulsions. LWT. 2021;141:110892.
da Silveira TFF, Cajaíba LM, Valentin L, Baréa B, Villeneuve P, Castro IA. Effect of sinapic acid ester derivatives on the oxidative stability of omega-3 fatty acids rich oil-in-water emulsions. Food Chemistry. 2020;309:125586.
Roschel GG, da Silveira TFF, Cajaiba LM, Castro IA. Combination of Hydrophilic or Lipophilic Natural Compounds to Improve the Oxidative Stability of Flaxseed Oil. European Journal of Lipid Science and Technology. 2019;121(5):1800459.
da Silveira TFF, Cristianini M, Kuhnle GG, Ribeiro AB, Filho JT, Godoy HT. Anthocyanins, non-anthocyanin phenolics, tocopherols and antioxidant capacity of açaí juice (Euterpe oleracea) as affected by high pressure processing and thermal pasteurization. Innovative Food Science & Emerging Technologies. 2019;55:88-96.
da Silveira TFF, de Souza TCL, Carvalho AV, Ribeiro AB, Kuhnle GGC, Godoy HT. White açaí juice (Euterpe oleracea): Phenolic composition by LC-ESI-MS/MS, antioxidant capacity and inhibition effect on the formation of colorectal cancer related compounds. Journal of Functional Foods. 2017;36:215-23.

You can view some of Dr Tayse´s work below and links to her professional profile:

ResearchGate: https://www.researchgate.net/profile/Tayse-Ferreira?ev=hdr_xprf

Scopus: https://www.scopus.com/authid/detail.uri?authorId=55901968900

Google Scholar: https://scholar.google.com/citations?user=l4zi0d8AAAAJ&hl=pt-PT

Linkedin: https://www.linkedin.com/in/tayse-ferreira-a2311947/

Dr Tayse Ferreira F. Da Silveira PhD

View More north_east

Reviewer bio

Dr Tayse has extensive experience in studying the chemical composition and stability of foods, as well as their bioactive properties.

Dr Tayse da Silveira´s Highlights:

Lecturer at the State University of São Paulo (Unesp), Brazil, for Food Engineering students
Post-doctorate in Food Science, with a one-year training period at Cirad – France.
PhD in Food Science, with a one-year scholarship at the University of Reading/United Kingdom.

Bachelor of Food Engineering at the Federal University of Pará, Brazil.

Professional experience:

In her doctorate at the University of Campinas, Dr Tayse studied the effect of emergent preservation techniques, such as high-pressure processing, on the chemical and microbial properties of foods.

During this period, Dr Tayse worked on the development and evaluation of innovative antioxidant molecules for the preservation of fatty food products.

In her research, she targets molecules able to provide health and nutritional improvement, and antioxidant and antimicrobial properties (natural food additives).

She regularly publishes in high-impact, specialized scientific journals in her field, and feels encouraged to expand her knowledge domain by doing new scientific partnerships.

Education

2017 – PhD in Food Science at the University of Campinas Brazil, with a one-year training period at the University of Reading/United Kingdom.

2013 – Master’s Degree in Food Science at the University of Campinas, Brazil.

2011 – Bachelor of Food Engineering at the Federal University of Pará, Brazil.

Relevant Published work

Roschel GG, da Silveira TFF, Cajaíba LM, Ferrari RA, Castro IA. Combination of natural strategies to improve the oxidative stability of echium seed oil. Journal of Food Science. 2021;86(2):411-9.
de Moraes MR, da Silveira TFF, Coutinho JP, Souza DS, Duarte MCT, Duarte RT, et al. Bioactivity of atemoya fruits and by-products. Food Bioscience. 2021;41:101036.
Ferreira da Silveira TF, Laguerre M, Bourlieu-Lacanal C, Lecomte J, Durand E, Figueroa-Espinoza MC, et al. Impact of surfactant concentration and antioxidant mode of incorporation on the oxidative stability of oil-in-water nanoemulsions. LWT. 2021;141:110892.
da Silveira TFF, Cajaíba LM, Valentin L, Baréa B, Villeneuve P, Castro IA. Effect of sinapic acid ester derivatives on the oxidative stability of omega-3 fatty acids rich oil-in-water emulsions. Food Chemistry. 2020;309:125586.
Roschel GG, da Silveira TFF, Cajaiba LM, Castro IA. Combination of Hydrophilic or Lipophilic Natural Compounds to Improve the Oxidative Stability of Flaxseed Oil. European Journal of Lipid Science and Technology. 2019;121(5):1800459.
da Silveira TFF, Cristianini M, Kuhnle GG, Ribeiro AB, Filho JT, Godoy HT. Anthocyanins, non-anthocyanin phenolics, tocopherols and antioxidant capacity of açaí juice (Euterpe oleracea) as affected by high pressure processing and thermal pasteurization. Innovative Food Science & Emerging Technologies. 2019;55:88-96.
da Silveira TFF, de Souza TCL, Carvalho AV, Ribeiro AB, Kuhnle GGC, Godoy HT. White açaí juice (Euterpe oleracea): Phenolic composition by LC-ESI-MS/MS, antioxidant capacity and inhibition effect on the formation of colorectal cancer related compounds. Journal of Functional Foods. 2017;36:215-23.

You can view some of Dr Tayse´s work below and links to her professional profile:

ResearchGate: https://www.researchgate.net/profile/Tayse-Ferreira?ev=hdr_xprf

Scopus: https://www.scopus.com/authid/detail.uri?authorId=55901968900

Google Scholar: https://scholar.google.com/citations?user=l4zi0d8AAAAJ&hl=pt-PT

Linkedin: https://www.linkedin.com/in/tayse-ferreira-a2311947/

Dr Tayse Ferreira F. Da Silveira PhD

View More north_east

In this short article, we are going to answer the question, “can dark chocolate go bad?” We will also pour some light on the storage and shelf life of dark chocolate. Moreover, we will tell you the ways to check the freshness of your dark chocolate.

Can dark chocolate go bad?

Yes, dark chocolate can go bad either beyond its shelf life or if it has been exposed to incorrect storage.

Dark chocolate is composed of cocoa mass, some sugar, cocoa butter, and lecithin. It does not take milk. Other ingredients like nuts or dry fruits can be present.

The limitation in the shelf life of chocolate can be due to diverse factors: fat bloom, sensory changes, and sugar bloom [1].

The low moisture of dark chocolate and products makes them microbiologically safe and stable at room temperature [1].

However, improper storage, processing, and packaging – for example, poor hygiene and moisture gain – may encourage microbial contamination and growth.

If non-chocolate ingredients are incorporated, such as nuts and waffles, extra concerns are introduced.

These products can be a source of contamination, as well as they easily absorb moisture under inadequate storage conditions, favoring microbial development.

How long does dark chocolate last?

Pure dark chocolate may survive up to two years if wrapped in foil and stored in a cool, dark, dry place [1].

If other ingredients – like nuts, raisins, and waffles – are incorporated, the shelf life will reduce to about one year.

The reason is that these extra components add spoilage factors to the chocolate, for example, they undergo fat oxidation and moisture pickup [1].

How does chocolate go bad?

Here are the main transformations taking place when dark chocolate goes bad.

Fat bloom: visibly recognized as a whitish superficial layer on chocolate accompanied by loss of surface gloss, the fat bloom is nothing more than fat crystallization on the surface of the chocolate.

Factors leading to fat bloom include storage at temperatures higher than 18°C, melting of chocolate followed by recrystallization, and inadequate processing conditions [2].

Sensory changes: chocolate is high in fat, so one sign that it has gone bad is rancidity caused by fat oxidation. Although dark chocolate is rich in antioxidants, over time, fat oxidation is inevitable.

Other sensory changes comprise stale favor, hardness, crumbliness, and loss of superficial gloss.

Chocolates incorporated with nuts may experience extra rancidity because nuts are usually rich in unsaturated fat. They can also lose texture due to moisture pickup.

Sugar bloom: means the crystallization of sugars on the surface of the chocolate, and is caused by moisture absorption.

Any of these signs can harm your health, they are just quality markers.

Although microbial growth is unlikely, incorrect storage conditions may somehow promote it. Therefore, upon any manifestation of mold, which shows a cotton appearance on the surface of the chocolate, discard the chocolate immediately.

What are the factors affecting the shelf life of dark chocolate?

The main factors affecting the shelf life of dark chocolate are product composition, storage conditions, and packaging.

Dark chocolate bars may last for up two years if well stored, but the presence of other ingredients, like raisins, nuts, and waffles, reduces this time by about half, after which sensory quality drops significantly [1].

Raisins will dry out, nuts become rancidity and gain moisture, as well as waffles.

According to reports in research, humidity, and temperature are key factors to protect the chocolate from many quality-associated issues, such as sugar crystallization, melting, and fat bloom [1].

Storage at 18°C and below is recommended to avoid fat bloom [2].

Last but not least, the use of appropriate packaging is most important in maintaining the quality of the products and achieving the required shelf life. The package must serve as a barrier to water vapor permeability.

In absence of an effective wrap for chocolate, products will tend to lose or soak up moisture. The buildup of moisture on the surface could then lead to mold growth on products [1].

How to Keep Chocolate Safe?

Chocolate should be kept in a dark, cool, dry area.

It’s OK to keep it in the cupboard or a kitchen cabinet; it doesn’t need to be refrigerated. After you’ve opened the bag, make sure it’s properly wrapped before putting it away.

Adequate stock conditions protect the chocolate from heat (which promotes melting, fat bloom, and fat oxidation); moisture (which causes texture loss and sugar crystallization; and light (which can favor fat oxidation).

The optimum shelf life is at temperatures of about 18 °C or less [1,2]. According to studies, in general, the lower the temperature, the lower the bloom risk [2].

if the temperature rises to 30°C, it isn’t a huge problem, but the chances to occur fat bloom are increased.

Above this temperature, chocolate is partially melted, and upon recrystallization, the fat bloom is very likely to take place [2].

Hold the bar far from any heat sources while storing it, since heat may melt the chocolate.

After you’ve opened the bar, cover the chocolate in the aluminum foil that came with it, or seal up the bag if it’s resealable.

Can I get sick from eating dark chocolate?

Unfortunately, yes, you can. Although chocolate is considered a safe and stable product due to its low moisture and high flavonoid contents, over the past years, many related outbreaks have been reported worldwide [3].

Morasi and others [4] highlighted in a recent study that pathogens like Salmonella ssp. can survive drastic processing conditions and endure strongly adverse ambient of low-moisture foods, including chocolate.

They reported that S. Eastbourne, a species of salmonella, survived in dark chocolate for up to 9 months at 20°C.

The authors also drew attention to the contamination of chocolate ingredients, such as nuts, peanuts, and almonds, which could take pathogenic microorganisms to chocolates.

The surviving bacteria will wait in the low-moisture product until favorable conditions come up, after which they develop quickly.

Therefore, is not a good idea to eat chocolate that you obviously see has been badly stored, for instance, exposed to moisture or mild heat.

If contaminated, these conditions are perfect for salmonella and other pathogens to grow.

Conclusion

In this short article, we answered the question, “can dark chocolate go bad?” We also poured some light on the storage and shelf life of dark chocolate. Moreover, we told you the ways to check the freshness of your dark chocolate.