2025.04.19
Nut history
Nuts are a type of dried fruit consisting of a seed (edible part), a hard shell (stiff and woody layer), and a protective covering (outer layer). These products are a good source of nutrients, including proteins, vitamins, minerals, unsaturated fatty acids which are the main part of unsaturated fats and are liquid at room temperature, bioactive compounds such as polyphenols that act as antioxidants to protect the body against damage, fibers, and more. Four types of nuts that fit precisely into this definition include chestnuts, hazelnuts, walnuts, and pecans (a type of tree nut with a crisp texture and sweet taste, richer than walnuts and with higher nutritional value). However, the term "nut" often has a broader meaning and includes legumes such as peanuts, seeds such as flax seeds, sunflower seeds, sesame, and more, and drupes such as almonds, pecans, pistachios, walnuts, and more. Nuts have been an important part of the human diet for thousands of years. These edible seeds have deep roots in human history and culture. The discovery of each of these nuts has a different story and their journey begins from different corners of the world.
Archaeological excavations have shown that nuts have been an important part of the human diet since about 780,000 years ago. Evidence obtained from a swamp includes 7 types of nuts, including wild almonds, spiny water lilies, blue chestnuts, and two subspecies of oak and pistachio, along with stone tools used to crack them. Among these, pistachios and blue chestnuts were similar to the types of nuts found today in the Far East (a region in East Asia and parts of Southeast Asia) and Northern Europe. In addition, archaeological evidence shows that special stone tools were used to crack nuts. These tools, called nut-cracking stones, have indentations resulting from cracking a large amount of hard nuts. Early Native Americans placed the nuts in these indentations and cracked them using another stone called a hammer stone. The kernels of the cracked nuts were eaten whole, or ground to make nut flour and butter. Also, the shells of the nuts were used as fuel after removing the kernels.
Almonds, as one of today's most popular nuts, have a history that goes back to ancient Mesopotamia and the Mediterranean. Historians say that almonds were among the first cultivated plants and have been found at excavation sites in Cyprus and Greece. In addition, cashews are native to South America, especially Brazil, and from there have been transferred to other tropical regions, including India, Africa, and Southeast Asia. This nut, which was initially ignored due to its poisonous shells, eventually became popular in the world due to its delicious kernels. Walnuts have long been a symbol of wisdom and intellect. In ancient Greece, it was considered brain food, and the Romans believed that walnuts could improve mood and the set of mental abilities controlled by different parts of the brain such as attention, concentration, memory, mental flexibility, etc. Evidence shows that the oldest remains of walnuts were discovered in Iraq and date back to 50,000 BC. The Greeks and Romans had a great interest in walnuts. England played an important role in the trade and distribution of walnuts throughout the Mediterranean during a period of history. English ships carried walnuts from producing regions to other places. Due to this prominent commercial role, walnuts are known as English walnuts. Walnuts were brought to California from Spain in the 18th century by Franciscan priests, and today this state accounts for a large part of the global walnut production. Pistachios also have a history that goes back more than 7,000 years. This nut was used by emperors and sultans. Hazelnuts, also known as filberts, have a rich history in European culture and cuisine. In a manuscript found in China, hazelnuts are among the five sacred foods that God gave to humans. Later, hazelnuts found a special place in confectionery and became a staple ingredient in products such as Nutella and praline (chocolate combined with nuts and caramel). The nut industry in Iran is an ancient industry that dates back thousands of years and forms an important part of Iranian agricultural life. Nuts have long been one of the most popular and common foods among Iranians, especially among urban dwellers. These delicious snacks have not only adorned gatherings and evenings but have also had a special place in religious celebrations and ceremonies. The widespread prevalence of nuts among different classes of society and their high consumption in traditional gatherings have boosted the nut-selling profession and the prosperity of this trade in the ancient cities of Iran. Old nut sellers, with their glamorous and decorated shops, added a spectacular appearance to the markets. They arranged all kinds of nuts with unique taste in special trays and dishes and artistically created a charming scene for passersby.
Global consumption rate of nuts
Considering an annual growth of 5.50%, the global nut market value will reach $70.23 billion in 2025. In other words, it is predicted that the nut market will continue to grow steadily and reach much higher revenues by 2030. In addition, the average per capita consumption (the average amount of consumption of a commodity by each person in a society in a certain period of time) in the nut market is expected to reach 1.2 kg per person in 2025. Increasing awareness of the health benefits associated with nut consumption, due to the presence of various vitamins, antioxidants, proteins, etc., has significantly increased nut consumption.
Potential risks in nuts, especially bulk nuts
- Use of artificial colors in nuts
Colors add variety and attractiveness to food, which increases its consumption. However, the use of food colors should not be to cover up product defects or deceive the consumer. In recent years, the consumption of artificial colors has increased in some products such as nuts. Although the use of certain artificial colors is permitted in some food products, the use of artificial colors in nuts is prohibited. For this reason, the use of artificial color causes the produced nut sample to be considered a non-consumable sample. Only naturally colored nuts are allowed and consumable. Some sellers add artificial color to old and stale nuts that may have changed color (pale, dark, spotted, etc.) to make them look beautiful. Stale nuts are nuts that have been stored for a long time since harvesting or processing, which can vary depending on the type of nut and storage conditions. Factors such as high heat and humidity, direct sunlight, and poor ventilation can cause faster spoilage of nuts. Usually, the substances used to color nuts are based on the use of heavy metals. These metals may have harmful effects on human health, such as causing chronic (long-term) kidney diseases, neurological disorders, damage to the respiratory system, fetal damage during pregnancy, birth defects, growth problems, liver damage, cancer, and more. In addition, colored nuts, depending on the type of color, may cause digestive tract allergies (such as abdominal pain and cramps, vomiting, etc.) in consumers.
- Roasting stale nuts
Stale nuts may have changes in taste such as bitterness, spiciness, etc., odor and etc., or have mold (a type of fungus that is often seen as spots of different colors, including green, gray, black, etc.), pests (presence of small and large holes on the nuts), etc. When storage of nut is prolonged, the possibility of the growth of mold increases. In addition, the fat in nuts, especially nuts such as walnuts, almonds, and pistachios, changes its state and develops an unpleasant taste if it is stale and spoiled. In nut supply centers, products that are stale or pest-infested may be roasted to improve their taste, aroma, and create a crisp texture. Roasting nuts hides their staleness and means exposing the product to heat. The improved taste, aroma, and color of roasted nuts are due to compounds that result from the reaction of the amino acid asparagine and natural sugar (such as glucose) in the kernels. This phenomenon causes the nuts to turn brown and occurs when the roasting temperature is above 120 degrees Celsius. During this reaction, a harmful substance called acrylamide may be formed. Almonds are more prone to acrylamide formation than other nuts because they contain more of the amino acid asparagine. Consumption of stale nuts can lead to complications such as food poisoning, liver damage, digestive problems (such as nausea, vomiting, diarrhea, and abdominal pain), increased risk of heart disease, Alzheimer's, damage to the nervous system, immune system disorders, inflammation, increased risk of cancer, and more.
- Use of polishes in nuts
Some nut shops use glossy wax-like substances, including natural waxes such as carnauba wax (E903), shellac (a type of natural resin secreted by an insect) and etc., to increase shelf life and create an attractive and shiny appearance in nuts, especially in stale nuts. These polishes, if used continuously and for a long time, can cause digestive problems, allergies, liver damage, and more.
- Mycotoxins (fungal toxins) in nuts
Mycotoxins are toxic compounds produced by some fungi such as Aspergillus spp., Penicillium spp., and Fusarium spp. These toxins can usually grow in products such as nuts. The presence of aflatoxin (a type of fungal toxin) in nuts is a major concern for consumers and regulatory organizations. Factors such as lack of product care during growth and before harvest, improper harvesting methods, and post-harvest processes (drying, packaging, storage, transportation, etc.) may affect the presence of aflatoxins. In addition, climate changes (such as changes in temperature and humidity) can also provide a favorable environment for fungal growth and aflatoxin production. Fungi such as Aspergillus flavus, A. parasiticus, A. nomius, etc., can produce aflatoxins in products such as pistachios, peanuts, walnuts, almonds, hazelnuts, etc. The 4 main types of aflatoxins include aflatoxin B1, aflatoxin B2, aflatoxin G1, and aflatoxin G2. Strict regulations for aflatoxins have been implemented by many countries to increase the safety of nuts as high-risk contaminated food products. Mainly, these regulations have been significant for the export and import of nuts worldwide. In addition, regulatory programs in countries have been implemented regarding public health risks associated with aflatoxin consumption through the consumption of various nuts. Ochratoxins (a type of fungal toxin) also have 3 main types, ochratoxin A, ochratoxin B, and ochratoxin C. Ochratoxin A is produced by fungi such as A. ochraceus and Penicillium verrucosum in some nuts and etc. The level of ochratoxins in nuts is usually lower than aflatoxins. Aflatoxin contamination of kernels is a serious threat. A strong correlation between aflatoxin consumption and the occurrence of cancer has been confirmed. The International Agency for Research on Cancer (IARC) has categorized aflatoxins in Group 1. Aflatoxin B1 is a toxin that can cause birth defects in the fetus, genetic mutations in DNA (hereditary material), alter the function of the immune system, and prevent the growth of cells (the smallest unit of life in the body) or tissues, which this effect can be very harmful in growing children and adolescents. Ochratoxin A has also been classified by the International Agency for Research on Cancer as a possibly carcinogenic substance for humans and in Group B2.
- Pesticide residues in nuts
Pesticides used in agricultural activities to achieve high productivity have benefits such as preventing insect damage to products. When pesticides are used excessively and improperly in an agricultural area, they can enter the soil and product and cause food contamination. Pesticide residues in nuts are a major concern because nuts may be exposed to various chemical toxins during different stages of production, from tree growth to processing and packaging. The most important pesticide residues in nuts include organophosphates (such as chlorpyrifos and diazinon), pyrethroids (such as deltamethrin and cypermethrin), carbamates (such as carbaryl), DDT, and other chlorinated toxins (banned toxins), etc. When the amount of pesticide that people receive by consuming other foods is considered, people can be exposed to acute (short-term) and chronic health risks from pesticide residues. The accumulation of harmful residues of plant pesticides in food can lead to health risks such as neurotoxicity, endocrine disruption, reproductive problems, possible increased risk of cancer, etc. Exposure to pesticides, especially for children and pregnant women, poses serious health risks. Children are particularly more vulnerable, and pesticides are a common cause of poisoning in them.
- Bacterial contamination in nuts
Nuts may be contaminated by pathogenic bacteria. Some harmful bacteria such as Salmonella and Escherichia coli may be present in raw nuts, as nuts may fall to the ground during harvest, and if the soil is contaminated with these bacteria, there is a possibility of transferring these contaminations to the nuts, or contact with a contaminated hand surface can transfer microbial contaminations to the nuts. Salmonella bacteria are considered a target microorganism in the study of tree nut contamination due to their long-term resistance and high heat tolerance in dry environments. Salmonella outbreaks have been associated with raw almonds, pistachios, pecans, etc. Other pathogenic bacteria that may be associated with contaminated nuts include Bacillus cereus, Clostridium botulinum, Clostridium perfringens, Cronobacter, Listeria monocytogenes, Staphylococcus aureus, etc. These bacterial contaminations can endanger a person's health. Consumption of Salmonella-contaminated nuts can lead to food poisoning, the symptoms of which include severe diarrhea, abdominal pain, fever and chills, dehydration, especially in children and the elderly, etc. Escherichia coli can also cause serious problems such as bloody diarrhea, kidney damage, etc. In addition, consumption of Listeria-contaminated nuts can cause high fever and body aches, severe headache, brain infection in people with weakened immune systems, miscarriage in pregnant women, etc.
- Salt in nuts
Salt is commonly an authorized additive in nut production, used to enhance flavor and extend shelf life. However, some producers use excessive amounts of salt, exceeding authorized levels, to further improve taste and etc. Long-term, excessive consumption of salted nuts can lead to high blood pressure, kidney damage and other health issues.
- Starch in nuts
Another permitted additive in nut production is starch, which can be obtained from potatoes, wheat, rice, etc. Starch is used as a binding agent in flavored or coated nuts (such as coated peanuts) so that spices and flavorings adhere better to their surface. In some cases, starch is used in the coating of fried or baked nuts to create a crisper texture. In addition, starch helps absorb excess moisture and prevents nuts from sticking together, which helps maintain product freshness. Some of these nuts may be coated with starches containing gluten (a type of protein found in wheat, barley, etc.). This type of starch can cause adverse reactions in celiac patients. Celiac disease is a chronic autoimmune disorder in which the body's immune system reacts to gluten. In people with celiac disease, consuming gluten causes the immune system to attack the lining of the small intestine and damage the intestinal villi. These villi play an important role in absorbing nutrients, so damage to them can lead to malnutrition and digestive problems.
Points to consider when buying and storing nuts
1- When buying nuts, it is better to choose raw nuts, which have a longer shelf life than roasted, polished, etc. nuts. If desired, you can roast the raw nuts in small quantities before consumption.
2- Many of us buy shelled nuts because they are more accessible and easier to use, but if you are looking for a higher quality nut with a longer shelf life, choosing nuts with shells is a better option.
3- If your hands and mouth are stained when consuming sunflower seeds, pistachios, almonds, and other nuts, it indicates the use of chemical colors in their preparation. For sunflower seeds, black chemical color may be used, or colored pistachios may have a very yellow and shiny shell or a dyed red kernel. In addition, if you put some nuts in your fist and wait a little, then empty the nuts and see if your hand is stained, then the nuts giving color to your hand is a sign of unsanitary conditions. Therefore, it is better to choose nuts with natural color when buying.
4- To reduce the risks of nut contamination with mycotoxins and increase consumption safety, avoid buying nuts that have unpleasant odors, abnormal spots, mold, etc. In addition, store nuts in a dry, cool place away from moisture and direct sunlight or heat. For longer shelf life, you can store nuts in the refrigerator or freezer.
5- For individuals with celiac disease, the consumption of raw nuts represents a safer dietary option. However, should they elect to roast the nuts, it is advisable to employ a low-heat method prior to consumption