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Introduction

Peanut butter is a traditional household item in which many families grew up with as a staple food in their diet. Many consume peanut butter for its flavor and texture, but some prefer peanuts on their own as a dietary choice. In the United States of America, peanut butter must be at least 90% peanuts or else it is deemed as peanut spread. In Canada however, there is no regulation regarding the percentage of peanuts allowed to be called peanut butter. In 2002, it was estimated that the average American child ate 1,500 peanut butter and jelly sandwiches before their high school graduation. From the original peanut butter, there are now a wide variety of flavors and products available for purchase. Some of these include: natural, chocolate, crunchy, smooth, unsweetened, whipped, extra creamy, light and addition of honey. Peanut butter’s usage is seen mostly in candies, sandwiches, snacks, cookies in the form of peanut butter coatings (cost approximately one-third as much as chocolate coatings), and cake fillings. Kraft peanut butter and Adam’s 100% Natural Creamy Unsalted Peanut Butter are prime examples of commercial and natural peanut butter products that are commonly purchased on a daily basis.

History

The creation of peanut butter dates back to the 15th century when the Aztecs used to mash roasted peanuts into a paste, the first known case of what we call peanut butter today. However, there are many influential people in the making of the modern peanut butter that has been a tradition in western cultures for over a hundred years.  In 1884, Marcellus Gilmore Edson of Canada invented peanut paste by crushing roasted peanuts together using two hot surfaces. Eleven years later (1895), cereal pioneer Dr. John Harvey Kellogg invented a version of peanut butter, where he was able to process raw peanuts creating the spread. Peanut butter however was first introduced at the St. Louis World’s fair in 1904. Twenty seven years later (1931), chemist Joseph Rosefield prevented peanut butter’s nature to separate by the addition of hydrogenated vegetable oil in which he named product ‘Skippy.’ Despite the given history of the product, the official title of peanut butter inventor was given to George Washington Carver. Even though he did not create peanut butter, he did suggest over 300 uses for peanuts. During the first two world wars, peanut butter had become a source of healthy and delicious protein, but nowadays, peanut butter has a multitude of different uses in hundreds of different recipes; becoming an influential food source in many households.  

Harvesting

Peanut Harvester

In order for peanut butter to be made, the peanuts must first be harvested from the plant that they grow on, which is a green bush-like plant that produces yellow flowers. The flowers on the peanut plant would wilt over until they are on top of the soil and the flowers would bore into the ground, thus starting the maturation process underground. The peanut plants are typically seeded in the springtime (April-May) and harvested in late summer to the beginning of fall (late August to early October). They are harvested by mechanical pickers and then transported to processing plants to be shelled and dried.

Processing

Heating Process

Before peanut butter can be made, the peanuts need to be shelled and all of the leaves, vines, and pods must be removed before processing. The peanuts would be placed in between a set of rollers that are specific to the size of the peanut in order to crack the shells. Once the shells are cracked off, they would be shaken and dried in order to get rid of excess material such as dirt and rocks. Once the peanuts are isolated from the excess material, a machine called a size grader separates the peanuts into different troughs depending on the size and quality of the peanut. After the initial processing is done, they are taken into trucks and delivered to manufacturers organized by their size. In order to maintain the quality of the peanuts, they must be refrigerated if the product is out for more than 60 days. Manufacturers would dry roast the peanuts once they are received by one of two methods: batch or continuous. The batch process takes place by distributing 400 pounds of peanuts in a rotating oven and heating them to about 425°C. The continuous method is done by heating the peanuts to 160°C for 40-60 minutes until they are roasted evenly. The reason there are two methods is because some manufacturers believe that the continuous method is more efficient and less labor intensive, while others believe the batch method is better able to cater to different levels of moisture in the peanuts.

Blanching the Peanuts

After the heating process, the peanuts are removed and cooled as soon as possible in order to ensure that all of the peanuts are cooked at similar conditions and time. Immediately they are placed in a large metal cylinder where cool air is blown onto the peanuts by a suction fan. The next step is to remove the skins of the peanuts by two different types of blanching; water and heat. Heat blanching is where the peanuts are exposed to 137°C for a minimum of 20 minutes in order to crack the skins. After they are cooled, they are put into a continuous stream with brushes and rubber belts through a blancher to remove the skins off of the peanuts. Water blanching is where the peanut is placed into a trough full of water and then are rolled onto tiny blades that cut the skins off from the peanut. After this process takes place, they are given a scalding hot water bath while on a conveyor belt, and then placed on a special pad that removes the skins completely. The peanuts are then dried by air with a temperature of 50°C for at least 6 hours. After blanching, they are inspected and the damaged or burnt peanuts are removed, ensuring all of the peanuts have good quality and appearance.

Grinding

The next process the peanuts would undergo is grinding.  The grinding mill is used to break down the peanuts into 2 stages. The first stage would produce a medium grind, whereas the second stage would produce a finer, butter-like grind which uses fast paced blades, using cutting and shearing actions on the peanuts.

For smooth commercial peanut butter made by Kraft for example, the addition of salt, hydrogenated oil stabilizer and dextrose are fed into the grinder simultaneously with the peanuts, along with other ingredients. Natural peanut butters, such as Adams 100% Natural Peanut Butter on the other hand, would not have any other ingredients added to it besides the peanuts. The grinder is kept at a constant pressure in order to prevent air bubbles. The stabilized peanut butter is then cooled in a rotating refrigerated cylinder until it is to be packaged.

Ingredients

Peanuts

Ingredients added to peanut butter may vary depending on what flavour is desired (e.g. chocolate, honey) and how the manufacturer wants to maintain nutritional quality, stability, and appearance. For natural peanut butters, no stabilizers or emulsifiers are added as peanuts are the only ingredients listed to create the product.  For commercial peanut butters, such as Kraft, peanuts, corn maltodextrin, sugar, soybean oil, salt, hydrogenated vegetable oil (cottonseed and grapeseed oil), monoglycerides and diglycerides are added to the product. Here, corn maltodextrin was used as a thickening agent (stabilizer) while monoglycerides and diglycerides were used as emulsifiers for emulsion (mixture of two phases which are not naturally soluble or miscible). Oils are usually added for its ability to work well alongside other fats; promoting a better flavor. The additional ingredients added to common commercial peanut butters are frequently used as flavor enhancers to the product.

Packaging & Preservation Methods

There are a few different methods on how peanut butter can be packaged. If a facility had liquid nitrogen available, it was sometimes added into the peanut butter jars where the liquid would eventually evaporate; removing oxygen in the process. The most common method however is the automatic packaging into glass or plastic jars to be then capped and labeled. To prevent oxidation, vacuum packaging is the most frequently used method in junction to the automatic packaging as it is relatively inexpensive in comparison to the use of liquid nitrogen.

Storage

Texture of Peanut Butter

Storage can have a tremendous impact on the quality of the peanut butter. Normally, natural peanut butters are stored at room temperature but after opening, refrigeration is needed to reduce separation. Commercial peanut butters, such as Kraft, can be kept at room temperature before and after opening of the product.

Separation

Commonly what occurs during storage is separation. A layer of liquefied oil from the peanut butter tends to form on the top of the product. In order to maintain a uniform mixture as much as possible, the addition of an emulsifier (e.g. monoglycerides and edible lipids) would assist in doing so. The emulsifier would create a crystalline structure so when the peanut butter is cooled, the structure would entrap the available oil, resulting in the prevention of separation from the ground peanut particles.

Storage Temperature

In addition to separation, the storage temperature is also critical, especially for natural peanut butter. From past experiments, natural peanut butter displayed stability and a relatively low microbial count during storage. It was seen at 10°C, a natural peanut butter exhibited a similar texture to commercial products up until the 8th week as well as without huge losses in oxidative stability until the 12th week. At higher storage temperatures however, such as 25°C and 35°C, the oxidative stability was shortened rapidly to only 4 weeks of storage. Similar results of most natural peanut butter should follow suit as what was found in the fore mentioned experiment.

Variations in Products

There are a multitude of different types of peanut butter on the market that can be separated into two distinct categories; commercial peanut butter and natural peanut butter. The type of peanut butter that is chosen to be consumed would differ in: the ingredients added (as mentioned before), texture (e.g. creamy, crunchy, and chunky textures), oiliness, storage, spread ability, and to a lesser extent, flavor. Natural peanut butters only consist of peanuts, and thus oil separation from the peanuts is likely to occur, causing the less dense oil to rise to the top of the peanut mixture. Natural peanut butter must therefore be manually stirred once opened, and stored at temperatures of at least 10°C. On the other hand, commercial peanut butter is a homogenized mixture and has partially or fully hydrogenated oil added to it to prevent oil separation from occurring; therefore can be stored at room temperature. Because of the absence of partially or fully hydrogenated oil in natural peanut butter, the product would be less smooth and more difficult to spread. Flavors may also differ between the two peanut butter types as commercial butters tend to have the addition of salt and sugar. Despite the differences between the types of peanut butter, whether commercially based or naturally based, the macronutrient content per serving remains remarkably similar.

Nutritional Benefits & Risks

Possible Nutritional Benefits

Depending on how much one consumes peanut butter, the product can present positive but also negative dietary impacts on the human health. It has been shown that peanut butter, nuts, and vegetable fat consumption can lead to a risk reduction of benign breast disease. There was a study from the Washington University School of Medicine that displayed girls between 9 to 15 years of age who consumed peanut butter and nuts frequently were 39% less likely to have benign breast disease by the age of 30.

Peanut Butter Cookies

In addition to benign breast disease, the consumption of peanut butter and nuts has the potential to lower the risk of type 2 diabetes in women. Having peanut butter and other nut products in the diet can also lower caloric intake and be used as a possible replacement to meat and refined grain products.

In a Harvard study, it has been highlighted that having small daily servings of peanuts and peanut butter would help lower the risk of coronary heart disease, obesity, and gallbladder disease.

Salmonella Risk

A potential issue regarding peanut butter however is Salmonella. Even though thermal processing is usually applied to these types of products with the expectation of the elimination of Salmonella, contamination through repacking and as an ingredient for other foods may still occur after the production of the food. The reason for the possible survival of Salmonella is the food products may not be exposed to conditions sufficient enough to destroy pathogens at the moment of consumption. Cross-contamination is also a tremendous concern regarding peanut butter as well as nearly all other food products.

In baking for example, survival of Salmonella in peanut butter cookies continuously decreased by increasing temperature based on a log scale. In terms of numerical values, baking the cookies for 10 minutes resulted in a minimum reduction of Salmonella of 4.8 log. Cookies baked within 13 and 14 minutes displayed a reduction between 5.2 to 6.2 log while ones baked for 15 minutes had no detectable Salmonella present. Proper baking of peanut butter cookies and other baked goods is essential in reducing Salmonella as much as possible.

Allergy Concerns

Peanuts are a major allergy concern as they are considered one of the ten priority food allergens. Experiencing an allergic reaction may result in: red and itchy skin, swelling, trouble breathing, speaking or swallowing, paleness, cramps and many more. It is also uncommon for affected children to outgrow their peanut allergies as it has been found only about 20% do so.

Experiments however have shown promise in reducing the allergen. The addition of phenolic compounds (a mixture of soluble and insoluble complexes with proteins) was seen to be able to extract most of the peanut allergen known as Ara h 1 and Ara h 2. This was done in the means of a reduction of IgE (an antibody that is responsible for activating allergic reactions) binding by the phenolic compounds. Peanuts and its other derivatives (like peanut butter) still remains a popular allergy in children unfortunately.

Conclusion

Peanut butter has been around for thousands of years, known for its versatility in various recipes regarding its flavor and contribution towards nutritional value to the diet of its consumers. Popularity of the product sky rocketed as a snack item with 94% of Canadians having it in their household in 2015. Although commercial peanut butter products contributes similar nutritional benefits to that of natural peanut butters, it can also be poor to one’s health if consumed in excess from the added sugar and food additives. With natural peanut butter having its sole ingredient being only peanuts, one is able to obtain full nutritional value without the fear of added ingredients that could be harmful. Consumers’ preference tends to be commercial peanut butter for its better flavor, texture, and low maintenance rather than natural peanut butter as it must be refrigerated, stirred before consumption and is less sweet. Canada has contributed to the development of the peanut butter known today and has become a traditional food in Western cultures around the world.