Brian Cliette

Understanding Rancidity: Foods High in Polyunsaturated Fats and How to Store Them

Ever wondered why some foods spoil faster than others? It’s all about the fats they contain. Foods high in polyunsaturated fats are notorious for going rancid quickly. These fats, while beneficial to our health, are sensitive to heat, light, and oxygen, making them prone to spoilage.

Foods High in Polyunsaturated Fats

When it comes to spoiling the meal, polyunsaturated fats are the main culprits. These types of fats are more vulnerable to heat, light, and oxygen, which accelerates the spoiling process.

So, what are the common foods high in polyunsaturated fats? Let’s dive into that now.

Walnuts, fish like salmon, canola oil, and soybeans are some of the food items that contain high levels of polyunsaturated fats. You might notice these foods going rancid quicker than others due to their fat composition. Sunflower seeds and flax seeds are also rich in these delicate fats.

Here’s a brief breakdown:

Food Item Polyunsaturated Fat Content
Walnuts 13.4g per ounce
Salmon 4.0g per 4 ounces
Canola Oil 8.1g per tablespoon
Soybeans 7.7g per half cup

These numbers clearly show that foods high in polyunsaturated fats are often part of our daily diet. It’s important, therefore, to store and prepare these foods properly to avoid rapid spoilage.

While choosing cooking oils, also consider those with a high smoke point and greater resistance to rancidity. Olive oil and avocado oil can make smarter choices as they are primarily made of monounsaturated fats, which are more stable than their polyunsaturated counterparts.

These choices can help extend the shelf life of foods. But, remember that proper food storage like refrigeration and using airtight containers to limit exposure to oxygen can make a significant difference in how long these foods stay fresh. You see, there are simple, effective ways to keep our food safe from premature spoilage. So, take the initiative and make smarter dietary choices to ensure longer food freshness and preserve the nutritional benefits of your meals.

Understanding Rancidity and Polyunsaturated Fats

Before delving deeper into the list of foods that spoil faster due to high levels of polyunsaturated fats, it’s essential to comprehend why this happens. Rancidity refers to the undesirable change in flavor, color, and aroma of food products caused by oxidation or hydrolysis.

When it comes to fats, there are two main types: saturated and unsaturated. Polyunsaturated fats, which fall under unsaturated fats, contain more than one unsaturated carbon bond or double bond in their molecule. They consist of essential fats that the body can’t make and need to be included in your diet, for instance, omega-3 and omega-6 fatty acids.

While these polyunsaturated fats offer numerous health benefits, they are susceptible to oxidation due to their chemical structure. The process of oxidation causes the breakdown and loss of these fats, leading to the unpleasant changes in taste, smell, and color – commonly referred to as rancidity.

Now that you have a good understanding of how rancidity and polyunsaturated fats are related, you’re probably wondering how to identify and prevent this occurrence. For starters, in storing these foods, always aim for cool, dark, and dry storage conditions. Another tip, when selecting cooking oils, opt for those with high smoke points and resistance to rancidity, such as olive oil and avocado oil.

Consider the way inside a grocery store or market. The outer edges are generally where you’ll find fresh produce, meats, and dairy products – foods that spoil faster. This encourages regular restocking, ensuring the supply is always fresh. Now, isn’t that smart design?

In the following sections, I’ll further break down the list of foods higher in polyunsaturated fats. This knowledge will empower you to make more informed choices when it comes to your dietary decisions. After all, it’s not just about what you eat; it’s about how and when you eat it.

Factors that Contribute to Rancidity

There are three primary factors that contribute most prominently to the rancidity of foods high in polyunsaturated fats: exposure to air, light, and heat.

Exposure to air plays a critical role in food rancidity. Oxygen from the air reacts with the fatty acids in foods, triggering oxidation. This process leads to the production of foul-smelling compounds which give rancid foods their distinctive off-putting smell and taste.

Darkness is ideal for storing food because exposure to light, particularly UV light, can accelerate oxidation. It’s important to know that it’s not just sunlight that contributes to this chemical reaction. Indoor lights, especially fluorescent lights, also emit UV light. So, if you’re storing food in a clear container, it’s best to choose a dark cupboard or pantry, rather than leaving it exposed on the counter.

Heat is another enemy of foods high in polyunsaturated fats. When these fats are heated, they start to decompose and release malodorous compounds – this is known as thermal oxidation, a process that occurs regardless of whether the food is being cooked or merely stored in a hot environment.

When it comes to protecting your food from those damaging factors, choosing the right storage conditions can make a huge difference. Ideally, foods high in polyunsaturated fats should be stored in a cool, dark and dry place. This is why these foods often have storage instructions to help you maximize their shelf life.

Contrary to what you might think, your refrigerator may not be these foods best friend. The average refrigerator is designed to preserve a range of different foods, but storing foods high in polyunsaturated fats in it might lead to the softening of fruits or the wilting of vegetables.

In my next section, I’ll provide a breakdown of which foods are most likely to go rancid due to their high level of polyunsaturated fats. I’ll share some helpful and easily applicable tips, helping you keep these foods fresher for longer, thus, making your diet healthier.

Foods Prone to Rancidity Due to Polyunsaturated Fats

It’s essential to understand that certain foods are more prone to rancidity than others, majorly due to their high content of polyunsaturated fats. Polyunsaturated fats are particularly vulnerable to oxidation. It’s this oxidation process that can lead the food to go rancid.

Some classic examples of foods high in polyunsaturated fats include:

  • Flaxseed and flaxseed oil
  • Fish and fish oil
  • Chia seeds
  • Walnuts
  • Soybean oil
  • Sunflower oil
  • Corn oil

The polyunsaturated fats present in these foods make them prone to rancidity if not stored appropriately. Additionally, some of these foods, such as oils, could darken and develop a bad odor or taste if they’ve become rancid.

However, it’s not just these foods you need to be cautious with. Here’s a breakdown of some consumer-favorite items that are high in polyunsaturated fats and are therefore more likely to go rancid:

Food Item Polyunsaturated Fat Content (per 100g)
Almonds 12.2 g
Brazil nuts 15.3 g
Pine nuts 34.1 g
Fried chicken 13.5 g
Egg yolk 16.1 g

These foods are notorious for oxidation and production of foul-smelling compounds when exposed to improper storage conditions. So, always remember to store these items in a cool, dark, and dry place.

It’s not all doom and gloom though. With the right storage techniques and regular checks, you can keep the freshness of these nutrient-packed foods intact. Later in this article, I’ll share more tips on how to keep these kinds of foods fresher for longer. And remember, a little awareness can go a long way in ensuring you’re eating fresh, healthy, and safe food.

Storage and Handling Tips to Prevent Rancidity

Knowing how to store and handle high-polyunsaturated fat foods can significantly decrease the rancidity rate. With proper measures, it’s possible to prolong their shelf life and retain their nutritional quality. Here are some tried-and-true tips:

Keep it Cool: Store your polyunsaturated fat-rich foods in a cool setting. This slows down the oxidation process and consequently, rancidity. For instance, oils such as flaxseed oil should be stored in the refrigerator.

Darkness Matters: Light, particularly sunlight with its piercing UV rays, can spur on oxidation. I’d suggest storing these foods in a dark place or using opaque containers. Dark glass bottles work great for oils and seeds.

Dry Environment is Best: Moisture can wreak havoc on these foods by encouraging microbial growth. A dry place such as a pantry or cabinet fittingly suffices for storage.

Seal it Right: Exposing these foods to air accelerates oxidation. So, I’d recommend keeping them in tightly sealed containers when not in use. Vacuum-sealed bags or containers with airtight lids are your best bet.

Use it Timely: Simply put, don’t let these foods sit on the shelf for too long. The fresher the food, the lower the odds of it going rancid.

Next, let’s delve into an equally crucial factor when it comes to dealing with polyunsaturated fats – cooking. Understanding the role of heat, methods of cooking, and smoke points of different oils will further equip us to avoid rancidity and enjoy the benefits these foods have to offer. And so, we’ll discuss Cooking Tips for Handling High-polyunsaturated Fat Foods in our following section.


I’ve walked you through the connection between polyunsaturated fats and rancidity. Foods like flaxseed, fish, chia seeds, and certain oils are particularly susceptible. Even fan favorites like almonds, Brazil nuts, pine nuts, fried chicken, and egg yolks aren’t immune. It’s crucial to store these foods properly to avoid spoilage. Remember – cool, dark, dry, and sealed is the way to go. Use them promptly to enjoy their best taste and nutritional value. In the end, it’s not just about knowing which foods are likely to go rancid. It’s also about how you handle and store them. Stay tuned for my next post where I’ll share some handy cooking tips for these high-polyunsaturated fat foods.

What is the relationship between rancidity and polyunsaturated fats?

Polyunsaturated fats are more susceptible to oxidation, which can lead to rancidity. Certain foods high in these fats tend to go rancid more quickly.

What are some examples of foods high in polyunsaturated fats?

Flaxseed, fish, chia seeds, various oils, almonds, Brazil nuts, pine nuts, fried chicken, and egg yolks are all high in polyunsaturated fats and more likely to go rancid.

How can I store foods to prevent rancidity?

Store foods high in polyunsaturated fats in a cool, dark, and dry environment. Make sure they are tightly sealed to prevent exposure to oxygen, and use them in a timely manner.

What will be discussed in the next section of the article?

The next section of the article will provide cooking tips for handling high-polyunsaturated fat foods to prevent rancidity and keep them fresher for longer.

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About me

My name is Brian Cliette; I help brands and entrepreneurs find sustainable paths to sales growth on the social internet.

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