Nuts, seeds and oils are a great source for minerals, vitamins, phytochemicals, antioxidants and fatty acids. Nuts and seeds are the building blocks of their respective plants. Everything that plant needs is contained in the nut or seed. This is why they are so powerful for us. They do however also have antinutrients. In order to protect themselves from predators while awaiting their growth, seeds have a barrier around them. This causes a bitter taste and might actually leach nutrients from your body if you eat them. Therefore you should always soak your nuts and seeds for 12 hours before eating them. This allows the protective barrier to break down. All you have to do is place them in water. Also, they should be kept in an environment that is away from heat, light and oxygen. These three things will cause the quality fats to break down.
You must also always be aware of allergies to nuts. Fungus might grow on them while in storage as well.
Now that we have a basic understanding of fats, we must discuss cooking oils. There are an incredible amount of oils on the shelves at the store. A quick list includes:
Vegetable, soy, cocunut, olive oil, sesame, canola/rapeseed, avocado, nut oils (walnut, macadamia, almond), butter, ghee (clarified butter), corn oil, safflower, sunflower, flax seed, peanut oil and grapeseed oil. So which do you use and when? Here are a few
Grapeseed oil – This oil has no flavor, is greenish in color and has a high smoke point which makes it ideal high heat applications such as stir-frying, deep frying and roasting vegetables.
Canola/Rapeseed oil – This oil is from Canada. Given that name instead of rapeseed for obvious reasons. This oil was historically highly laden with genetically modified organisms (GMO’s) however you are now able to find it unrefined and organic. It is a good source of Omega 3 fatty acids and is also good for higher heat such as stir-frying and deep frying. It can also be used in baking. It is mostly a monounsaturated fat. It is processed at a high heat which can reduce the health benefits of the product.
Olive oil – Olive oil is a monounsaturated oil. Everyone typically sees it as a healthy oil. There are two main kinds of Olive Oil: extra virgin and olive oil. Extra virgin is good in situations where you are using lower heat to cook or not cooking at all (light sauteing, salad dressings), and olive oil would be used in medium heat applications. Olive oil should be green in color and should have a taste. The oils you use should be an ingredient in your foods.
Cooking Temps for oils
Higher Temps (375 F and up) – Ghee, cocunut, butter, avocado, grapeseed (medium-high heat sauteeing), canola oil (medium-high), macademia (medium-high),
Medium Temps (325 F) – Nut oils, canola, sesame, olive oil, corn, safflower, sunflower, soy
Low Temps (212 F) – all of the above
No heat – toasted sesame oil, flax seed (keep this in the refridgerator)
Labeling is very important with oils. Due to the fact that oils are fats and that light, oxygen and heat are enemies of fats which will cause them to go rancid it is very important to look at the labeling on the packages. Labels include things such as unrefined , cold pressed/expeller press , chemical extraction and refined. Unrefined and cold pressed are very good. It means that there has not been any sort of chemical process done to the oil. Cold press/expeller press ensures that the temperatures have been kept at a minimum allowing the highest quality oil with the lease amount of rancidity due to heat. Chemical extraction could potentially have hexanes from the extraction process in it and refined oils have some of the nutritious benefits removed from them. However refined oils will be able to be used in higher heat cooking applications.
Update: this is a great article a out cooking oils and cholesterol. At the least it explains why one MUST use the proper oil for the proper heat.