Do sunflower seeds go bad? (+5 spoilage signs)

In this brief guide, we will address the question, “Do sunflower seeds go bad?”. We will also discuss the shelf life of sunflower seeds, how you can tell if they have gone bad, and how you can properly store them.

Do sunflower seeds go bad?

Yes. Your sunflower seeds can go bad. Over time, the oils present in sunflower seeds undergo spoilage, as a result, the lipids in the seeds begin to break down due to the oxidation process, which is increased by exposure to heat, light, and air. This results in odd tastes and a spoiled taste (1). 

What is the shelf life of sunflower seeds?

Normally, if you buy a sealed packet of sunflower seeds and store them correctly in cool and dry conditions, they can remain fresh for about one year from the production date. It’s worth emphasizing that ensuring proper storage, specifically by keeping them in a cool and dry place, is essential to maintaining their quality over a longer period. Don’t forget to check the “best by” or expiration date on the packaging, as manufacturers provide specific recommendations (2).

At room temperature, unopened sunflower seeds generally retain their quality for approximately 3 to 6 months without any significant loss (2).

Once you open the package, it’s advisable to consume the sunflower seeds within a few months to ensure they retain their freshness and delicious flavor. So, make sure to enjoy your sunflower seeds before they lose their quality.

What affects the shelf life of sunflower seeds?

Sunflower seeds have a limited shelf life, and a number of factors can affect how fresh and high-quality they are. According to science, high temperatures can hasten the lipids in sunflower seeds to breakdown, causing rancidity and off-tastes (3,4).

Sunlight and other light sources can also encourage sunflower seed oxidation, which results in the breakdown of key minerals and oils. The flavor and nutritional value of an item may decrease as a result of this oxidation process. Sunflower seeds’ nutritious value is maintained through dark storage, which slows down the oxidation process (1-3). 

Moisture absorption can also decrease the shelf life of sunflower seeds. When exposed to moisture, sunflower seeds can become a breeding ground for mold and other microbes, leading to spoilage (5). 

The lipids included in sunflower seeds are also oxidized as a result of contact with oxygen. Rancidity and a drop in quality are the results of this oxidation process. Sunflower seeds’ freshness and taste may be maintained by using airtight packing or containers to reduce oxygen exposure (2,4,6). 

How can you tell if sunflower seeds have gone bad? 

Appearance

When sunflower seeds start to go bad, you may notice changes in their appearance, like discoloration or even black patches. This happens due to the breakdown of the fats, or lipids, present in the seeds. When these fats undergo oxidation, they can create darker areas or spots on the seeds, and this discoloration is a clear sign that the seeds have undergone degradation, which can affect their taste and quality. If you spot any unusual or blackened patches on the seeds, it’s a good idea to discard them to avoid consuming rancid or spoiled seeds (7,8).

Odor

If you detect a funky or off-putting odor and taste when you check your sunflower seeds, it’s a clear scientific indication that the oils have degraded due to oxidation. This occurs when the oils in the seeds start to degrade. Scientifically speaking, the breakdown of unsaturated fatty acids in the oils produces some volatile compounds that give off a rancid or unpleasant smell and flavor (9,10). 

Flavor

When sunflower seeds are going bad, off-flavors, such as bitterness or disagreeable tastes, can emerge as a result of the breakdown of lipids and proteins. A softer or mushier consistency can come from the breakdown of proteins and the absorption of moisture, which can also cause the loss of texture and a change in mouthfeel.  Science has shown a connection between the declining seed quality and these changes in flavor and texture (8-10). 

Mold growth

If you notice any fuzzy or discolored patches on your sunflower seeds, it is an indication that molds have developed due to moisture absorption. When sunflower seeds become contaminated with moisture, they create favorable conditions for microbial growth, including molds such as Alternaria, Fusarium and Rhizopus species (11).

The presence of moisture promotes the growth of mold spores, which can multiply rapidly on the surface of the seeds. The patches can vary in color, ranging from green, blue, and white to black, depending on the type of mold present. It’s important to note that molds can produce toxins called mycotoxins, which can pose health risks if ingested (12,13).

Insects

Sunflower seeds may attract insects that feed on and infest them if they are kept in less-than-ideal circumstances or for a long time. Insects like beetles, weevils, and moths are typical pests that attack sunflower seeds that have been kept. Small holes or tunnels that form in the seeds or the development of adult insects near the stored seeds are signs that they are there (14,15).

How can you properly store sunflower seeds?

To properly store sunflower seeds, it is important to keep them in a cool, dry place, such as the refrigerator, or freezer, in airtight containers. The optimal temperature in the refrigerator should be 4 °C and 38-43 relative humidity, while the freezer can be -20 °C (2). 

Additionally, storing under these conditions and ensuring the containers are tightly sealed help prevent oxidation and the development of off-flavors. Do not forget to regularly check for signs of spoilage and discarding any compromised seeds helps maintain freshness.

What happens if you consume spoiled sunflower seeds?

There are a few potential hazards to be aware of if you ingest spoiled sunflower seeds. Spoiled seeds may contain hazardous bacteria, molds, or poisons that can cause foodborne illness. As a result, symptoms such as nausea, vomiting, diarrhea, and stomach discomfort may ensue (11,12,16).

Consuming spoiled seeds can cause food poisoning in extreme circumstances. Also, as we mentioned before, damaged seeds may have a disagreeable flavor or odor as a result of rancidity or contamination, which may cause stomach distress (4,6). To avoid or minimize any health problems, it is important to remove any damaged sunflower seeds and avoid ingesting them.

Conclusion

In this brief guide, we addressed the question, “Do sunflower seeds go bad?”. We also discussed the shelf life of sunflower seeds, how you can tell if they have gone bad, and how you can properly store them.

References

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References

1.-

Abreu LAS, et al. Deterioration of sunflower seeds during storage. Journal of Seed Science, 2013, 35, 2, 240-247.

2.-

Lima DC, et al. Storage of sunflower seeds. Revista Ciência Agronômica, 2014, 45, 2, 361-369.

3.-

Valdés García A, Beltrán Sanahuja A, Karabagias IK, Badeka A, Kontominas MG, Garrigós MC. Effect of Frying and Roasting Processes on the Oxidative Stability of Sunflower Seeds (Helianthus annuus) under Normal and Accelerated Storage Conditions. Foods. 2021, 26;10(5):944

4.-

Dunford NT. Oxidative Stability of Sunflower Seed Oil. Sunflower Chemistry, Production, Processing, and Utilization, 2015, 465-489.

5.-

Mousa KA, et al. Effect of Moisture Content on Sunflower Seed Physical and Mechanical Properties. Int J Engineering Research in Africa, 2021, 57:169-179

6.-

Şahin S, Kurtulbaş E, Toprakçı İ, et al. Determination of lipid oxidation in sunflower oil treated with several additives. Biomass Conv. Bioref. 2023, 13, 3953–3961.

7.-

Ma F, Wang J, Liu C, et al. Discrimination of Kernel Quality Characteristics for Sunflower Seeds Based on Multispectral Imaging Approach. Food Anal. Methods, 2015, 8, 1629–1636.

8.-

Wiebach, J, Nagel, M, Börner, A, Altmann, T, Riewe, D. Age-dependent loss of seed viability is associated with increased lipid oxidation and hydrolysis. Plant Cell Environ. 2020; 43: 303–314.

10.-

Harman G, Mattick L. Association of lipid oxidation with seed ageing and death. Nature, 1976, 260, 323–324.

11.-

Addrah ME, Zhang Y, Zhang J, Liu L, Zhou H, Chen W, Zhao J. Fungicide Treatments to Control Seed-borne Fungi of Sunflower Seeds. Pathogens. 2019, 27;9(1):29. 

12.-

Dijksterhuis J. The fungal spore and food spoilage. Current Opinion in Food Science, 2017, 17, 68-74

13.-

USDA. What are Mycotoxins? 2018. 

14.-

Agrawal S, Panwar R, Kumar A, Singh IK, Singh A. Seed-Infesting Pests and Its Control Strategies. In: Tiwari, A.K. (eds) Advances in Seed Production and Management. Springer, Singapore, 2020.

15.-

USDA. Stored Grain Insect Reference. 2015.