Craving some nuts in the morning? Don’t eat stale nuts!

Nuts have always been the first choice of snacks for many people. Eat some with oatmeal yogurt for breakfast, or a few with morning tea or afternoon tea. They can satisfy your cravings and provide nutrition. However, although everyone knows that nuts are healthy foods, rich in unsaturated fatty acids, high-quality protein, trace elements, etc., if the nuts you choose are not fresh, not only will the taste be affected, but the nutrition will also be greatly reduced. If the uneaten nuts are not stored properly, they are prone to mold and have adverse effects on human health. Therefore, nuts must be fresh. Today, let's discuss the health hazards of stale nuts.

01. Grease and oil degradation and its impact

I have done some research on cancer before, and I learned about aflatoxin, a carcinogen. If nuts are not packaged well or stored properly, they may also deteriorate and produce this substance, which almost made me give up nuts for a while. There are two main hazards of stale nuts, namely oil rancidity and mold, and both factors are harmful to health.

Oil rancidity and its effects. Rancidity refers to the oxidation reaction of oils and fats caused by external factors such as oxygen, water, light, heat, and microorganisms, which will produce volatile substances with a special odor. Rancidity can be divided into three categories: auto-oxidation, photosensitive oxidation, and enzymatic oxidation, depending on the different peroxides in the oil oxidation process. For nuts rich in oil, the main reason for rancidity is the auto-oxidation of unsaturated fatty acids due to contact with air.

So what are the effects of oil and fat rancidity on health? Current research suggests that the main hazards are substances such as peroxides and free radicals produced by oil and fat oxidation. These substances themselves can stimulate cells and accelerate cell damage. In severe cases, they may cause various diseases in the body, such as destroying the stability of the intestines and causing gastrointestinal discomfort and diarrhea [1]. Therefore, it has become a subject of much concern. The national standard GB 19300-2014 "National Food Safety Standard for Nuts and Seeds" clearly defines the oxidation value of nuts, which indicates the degree of oxidation of oils and fatty acids, and is used to determine whether food has deteriorated due to oxidation.

02. Mildew and its impact

Mildew is a common natural phenomenon, which refers to the phenomenon that food will cause mold and other microorganisms to multiply under certain temperature and humidity conditions. The main reason for this phenomenon is that microorganisms are everywhere. Once the bag is opened, microorganisms will find their way to the nuts. Nuts themselves are nutritious foods. Once the conditions are right, microorganisms will begin to proliferate. Of course, in addition to microorganisms in the air, there are also some microorganisms on the nuts themselves that are difficult to kill. In particular, some microorganisms will produce spores to increase their resistance when encountering adverse environments. As a result, the microorganisms are difficult to kill and begin to multiply once they encounter suitable conditions.

Moldy has a significant impact on nuts. Not only does it change the flavor of the nuts themselves, but it can also cause serious health problems. Common microorganisms that cause mold include the familiar Aspergillus flavus. If nuts are not properly stored, they will be contaminated by Aspergillus flavus at a certain humidity and temperature and become moldy. Aspergillus flavus will secrete aflatoxin, a highly toxic substance that can cause fever and vomiting, and in severe cases, can be life-threatening [2]. Even more troublesome is that even a small amount of intake is risky because aflatoxin is a strong carcinogen.

03. How to avoid choosing unfresh nuts?

Whether it is an oxidative rancidity or mildew problem, although there are clear testing standards in the industry, it is much more difficult for ordinary people to identify it. What we can do is naturally to choose fresh nuts, which can be judged by the production date . It is also the best way to avoid the health risks caused by these problems.

But many times, the reality is not so. The production of a bag of nuts requires a long cycle. They are planted and picked in various places, then transported to a unified production factory for processing, and then packaged and transported to all parts of the country before they reach everyone's hands. All of this requires time, which brings a huge test to the production of nut companies, that is, how to "keep fresh". In this regard, many nut companies are working hard to research new nut preservation technologies to promote the preservation of nuts.

In general, for nuts, it is best to choose products with a recent production date. On this basis, it is also very necessary to choose products from companies that have advanced technology in nut preservation and focus on the freshness and quality of nuts.

[1] Cao Jun. Study on the oxidation law and kinetics of edible oils with different fatty acid structures[D]. Nanchang University, 2015.

[2] Bai Xiaoling. Preparation and identification of monoclonal antibodies against aflatoxin B_1[D]. Inner Mongolia Agricultural University, 2009.