Can cashews go bad?

In this brief guide, we will answer the query, “Can cashews go bad?” and will discuss how to properly store the cashew nuts.

Can cashew nuts go bad?

Yes, cashew nuts can go bad. The formation of off-odors, the darkening of the nuts and the development of unpleasant flavor are evidence that the cashew nuts have gone bad. In addition, mold is one of the signs that your cashew nuts have gone bad.

Rancidity is due to oxidation of lipids and lead to the generation of off-flavors and degradation of colors and nutrients (1).  

How to tell if cashews have gone bad?

Expired cashew nuts may be identified by the oxidation of lipids. Nuts contain a high amount of lipids and their deterioration, occurring during long storage, leads to the formation of secondary chemical compounds, such as aldehydes and ketones, which are off-odors. 

When cashew nuts are at their height of freshness, they tend to have a pleasing scent and a creamy flavor. However, with time, the nuts will darken and develop unpleasant odors. Many volatile compounds are produced by nuts and oils during lipid oxidation and they can be easily noticed, thus they have strong characteristic odors and off-flavors (2).

Another indicator of degeneration is the development of shriveled, darker skin. Lipid oxidation can also lead to a darkening of color by the formation of melanoidins and a loss of color due to free radical destruction of conjugated double bonds (1).

In addition to rancidity, inappropriate storage conditions such as high temperatures, relative high humidity, light incidence and long-term storage can significantly influence the formation of aflatoxins in nuts. Mycotoxins are toxigenic secondary metabolites of filamentous fungi and have a cumulative effect with a risk of causing damage in the liver and kidney (4).

How to Keep Cashew Nuts Fresh Long-Term?

To keep cashew nuts fresh for a long time, it is necessary to properly store them, avoiding light, humidity and heat. Regardless of how you want to use them, you must understand how to properly store these nuts.

Because cashew nuts contain a high amount of oil in its composition, they are highly susceptible to oxidation.

Environmental conditions which may accelerate the deterioration of food include exposure to heat, sunshine, humidity and the atmosphere (oxygen) itself. In addition, these nuts lack natural protection against these causes since they are offered without their shells. Storage of kernels with their skin (testa) on also reduces oxidative rancidity as the skin or testa acts as an oxygen barrier, minimizing lipid oxidation. The use of packages with high humidity, light and oxygen barriers are useful, as well as low temperatures for the storage (2).

After purchasing cashew nuts in bulk, such as a brown bag, you should store them in an airtight container or freezer bag. As a result, less air is being exposed.

Open the plastic bag if you purchased them and place them in one of the containers listed above. For example, if they arrive in an airtight container, you may store them in the jar before and after you open them. Ideal storage conditions for nuts are generally low temperatures (from 4 to 15°C), low moisture content (around 2.5%), low relative humidity (40–60%), low oxygen concentration (< 2.5%) and dark conditions (2).

Where to store cashew?

To store cashew nuts, keep them away from moisture and from high temperatures. In most cases, pre-packaged cashew nuts may be kept at room temperature until opened. In the jar or plastic container, they are safe but keep them out of direct sunlight and other sources of heat. Storage conditions determine the shelf life of the nuts, because light incidence, high temperatures, oxygen exposure and high humidity accelerate oxidation processes of lipids (2).

The quality of the nuts only lasts a short time after the package is opened. Refrigeration or freezing is the only option if you want to keep the food fresh for longer. Cashew nuts purchased in bulk have the same fate as those purchased individually. For short-term storage, store items at room temperature; for long-term storage, place them in the refrigerator or freezer. Low temperatures slow down the reaction rates of lipid oxidation (5).

However, the exposure of nuts into moisture may accelerate the oxidation and darkening. To store cashew nuts in the refrigerator or freezer, a moisture-barrier packaging is required. For this, the best options are airtight containers or freezer bags. Using resealable bags saves room in the freezer while also being more environmentally friendly. Before closing the box, make sure to remove as much air as possible. If the original container is well-sealed and freezer-friendly, you may use it. 

Studies demonstrated that nuts stored at -20°C had better kernel quality, lower level of lipidic oxidation and a higher antioxidant activity compared with nuts stored at 0°C (3).

For how long may cashews be stored in the pantry?

In the panty, cashew nuts may be kept for 2 weeks to 6 months, depending on the characteristics of the nuts and their packaging. While an unopened oxygen and moisture-barrier packaging can preserve the nuts for many months, an opened packaging will not. 

Rancidity is more prevalent in these nuts than in other types of foods. Shelf life refers to how long an item may be stored without being rancid and losing its creamy flavor and nutritional content.

Let’s begin with a wholesale purchase of raw cashew nuts. These may be stored in the pantry for up to a month, but at 30°C for 3 weeks (2), and in the fridge for up to six months. Freeze them for long-term storage. It is important to keep them safe from humidity, thus a high water activity decreases the shelf life and develops molds or other microorganisms. Water activity is the amount of free water available in food samples that is able to take part in enzymatic, physical and chemical reactions (2).

Most cashew nuts in pre-packaged form have a “best-by” date. This also implies that the nuts may be kept in the pantry or kitchen until then, unopened. You may not have known this, but the shelf life varies greatly across merchants and manufacturers. Typically, it lasts between six months to a year, although this might vary. It’s all down to how the nuts are handled before they’re put into the package.

Once opened, the nuts should keep in the pantry for two weeks and in the refrigerator for roughly a month (6). You may freeze the cashew nuts again if you need to keep them for a longer period. If you keep the nuts in the refrigerator, they’ll likely stay longer before becoming rancid, but it’s impossible to know precisely how long.

Conclusion

In this brief guide, we answered the query, “Can cashews go bad?” and discussed how to properly store the cashew nuts.

References

1. Vieira, Samantha A., Guodong Zhang, and Eric A. Decker. Biological implications of lipid oxidation products. J. Am. Oil Chem.’ Soc., 2017, 94, 339-351.
2. Gama, Tsvakai, et al. Quality and shelf life of tree nuts: A review. Sci hortic, 2018, 242, 116-126.
3. Ma, Yanping, et al. Physiochemical Responses of the Kernel Quality, Total Phenols and Antioxidant Enzymes of Walnut in Different Forms to the Low-Temperature Storage. Foods, 2021, 10, 2027.
4. Ajith, Sabna, et al. Effect of storage temperatures and humidity on proximate composition, peroxide value and iodine value of raw cashew nuts. J Food Sci Technol, 2015, 52, 4631.
5. Guiné, Raquel PF, et al. Modelling the influence of origin, packing and storage on water activity, colour and texture of almonds, hazelnuts and walnuts using artificial neural networks. Food Bioproc Technol, 2015, 8, 1113-1125.  
6. Van Laanen, Peggy. Safe home food storage. Texas University. 2002.