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Peanut Butter Packaging Process

Planting and harvesting

Peanut harvest

Due to weather conditions, peanuts are usually planted in Spring. The peanut comes from a yellow flower which bends over and infiltrates the soil after blooming and wilting, and the peanut starts to grow in the soil. Peanuts are harvested from late August to October, while the weather is clear. This weather allows for dry soil so that when picked, the soil do not stick to the stems and pods. The peanuts are then removed from vines and transported to a peanut shelling machine for mechanical drying. After cropping, the peanuts are delivered to warehouses for cleaning, where they are stored unshelled in silos.

Shelling

The most important thing about shelling is to remove the shell of peanuts with the smallest damage to the seed. The moisture of the unshelled peanuts is controlled to avoid excessive frangibility of the shells and kernels, which in turn, reduces the amount of dust present in the plant. After, the peanuts are sent to a series of rollers set specifically for the batch of peanuts, where they are cracked. After cracking, the peanuts go through a screening process where they are inspected for contaminants.

Roasting

During the dry roasting process, peanuts can be dried by either the batch or continuous method. In the batch method, peanuts are heated in large quantities in a revolving oven at about 426.6℃.  Next, the peanuts in each batch are uniformly held and roasted in the oven at 160℃ for about 40 to 60 minutes. This method is good to use when the peanuts differ in moisture content. The continuous method is different from the batch method. In the continuous method, a hot air roaster is used instead of an oven. The peanuts continuously pass through a hot air roaster in a rocking motion. This allows for even roasting of the peanuts. Also, this method can lower spoilage rate; it doesn't require much labor-intensive, and therefore, many large industries prefer to use continuous method in the dry roasting process. A photometer indicates the completion of dry roasting.

Cooling

After dry roasting, peanuts are removed from the oven as quickly as possible and directly placed in a blower-cooler cylinder. There are suction fans in the metal cylinder that can pull a large volume of air through, so the peanuts can be cooled more efficiently. The peanuts will not be dried out because cooling can help retain some oil and moisture. The cooling process is completed when the temperature in the cylinder reaches 30℃.

Blanching

After the kernels have been cooled down, the peanuts will undergo either heat blanching or water blanching to remove the remain seed coats. Compared to heat blanching, water blanching is a new process. Water blanching first appeared in 1949.

Heat Blanching

Peanuts are heated by hot air at 280 degrees Fahrenheit (137.3 degrees Celsius) for not more than 20 minutes in order to soften and split the skins. After that, the peanuts  are exposed to continuous steam in a blanching machine. The skins are then removed using either bristles or soft rubber belts. After that, these skins are separated and blown into waste bags. Meanwhile, the hearts of peanuts are segregated through inspection.

Water Blanching

After the kernels are arranged in troughs, the skin of the kernel is cracked on opposite sides by rolling it through sharp stationary blades. While the skins are removed, the kernels are brought through a one minute hot water bath and placed on a swinging pad with canvas on top. The swinging action of the pad rubs off the skins. Afterward, the blanched kernels are dried for at least six hours by hot air at 120 degrees Fahrenheit (48.8 degrees Celsius).

After blanching, the peanuts are screened and inspected  to eliminate the burnt and rotten peanuts. A blower is also used to remove light peanuts and discoloured peanuts are removed using a colour sorting machine.

Grinding

After blanching the peanuts are sent to grinding to be manufactured into peanut butter.  The peanuts are then sent through two sizes of grinders. The first grinder produces a medium grind, and the second produces a fine grind.  At this point, salt, and a vegetable oil stabilizer are added to the fine grind to produce the peanut butter.  This adds flavour and allows the peanut butter to stay as a homogenous mixture.  Chopped peanuts may also be added at this stage to produce “chunky” peanut butter.

Packaging

Before packaging, the peanut butter must first be cooled in order to be sealed in jars.  The mixture is pumped into a heat exchanger in order to cool it to about 48.8 degrees Celsius.  Once cool, the peanut butter is pumped into jars and vacuum sealed.  This vacuum sealing rids the container of oxygen so that oxidation cannot occur, preserving the food. The jars are then labelled and set aside until crystallization occurs. The peanut butter is then packaged into cartons distributed to retailers, where they are stored at room temperature and sold to consumers.