Nowadays, there is no cinema without popcorn. The product’s name is derived from the popping sound the grains of corn make when they are roasted.
Popcorn is therefore simply roasted corn. The dry corn contains fluid on the inside, creating steam in the grain when it is heated. So the popping and jumping of the grains during the preparation of the popcorn is caused by the expanding of the content of the grain, while the though peel does not yield. At a given moment, the peel breaks with relatively a lot of power and sound. The grains are exploded, so to speak.
Corn, Zea mays ssp. Mays, is a type of grain from Central America and belongs to the monocotyledons. So the extra food of the corn is stored in the endosperm. For the production of popcorn, the corn called popcorn is used. This is a special type of corn, which contains a lot of fluid in the grain. The white and yellow species without chaff are usually used for microwave popcorn.
There are two types of popcorn:
Large and irregular and therefore suited for salt popcorn, as salt gets stuck easily inside the irregularities.
Round shape and therefore suited for sweetened popcorn, as the coating can be spread over the popcorn equally.
Corn consists mainly out of carbohydrates. The product also contains some proteins, oil, fibres and minerals. When prepared without oil, the popcorn contains very little calories.
Nowadays, prepared popcorn is available, as well as popcorn which is easy to prepare in the microwave or grains which have yet to be roasted in the old fashioned manner.
Popcorn grows best in rich soil. The hybrid corn species, that are the cross-breeding of two inbreeding lines of species, are selected on qualities like tasteful grains, quantity of fluid in the grains and the number of grains per ear.
The corn plants are planted in such a way that harvesting can be done by means of machines. Pollination is by wind.
When the spadices have ripened, the plants are harvested as a whole by means of a combine. The combine removes the spadices mechanically, peals them and removes the grains. It is also possible to harvest the spadices directly without harvesting the entire plant. This harvesting method does less damage to the spadices and leaves the grains of corn on the spadices.
It is important that harvesting is done at the right time, because the fluid content of the corn determines whether the corn will be able to pop. It is best to harvest when the fluid content lies between 16 and 20%.
After harvesting the grains of the spadices, the corn is, depending on the harvesting method, dried naturally for 8 to 12 months in cribs. However, the drying period can be shortened by blowing hot air through holes in the bottom of the cribs. The corn is dried until the grains have reached a fluid content of approximately 13,5 to 14,0%. This fluid content is ideal for the preparation of popcorn.
In the factory, the grains of corn are removed from the spadices by means of a scalper.
Cleaning and sorting
The unwanted parts of the grains are removed by means of a de-stoner and a series of screens. The grains are then polished by means of metal brushes, to remove the chaff.
After the polishing, gravity is used to separate the good grains from the bad. The matured grains are lighter in weight, therefore the bad grains fall to the bottom of the centrifuge. This method also separates the too small grains which come from the tips of the spadix.
Any remaining dirt is then blown of the grains by means of fans. If necessary, the grains are also treated with a natural, inert fumigant, which is legally permitted to prevent decay due to insects during storage for a longer period of time.
Finally, the grains of lower quality are vacuumed up manually.
The corn is now ready to be roasted in the factory. The kernel of the grains then reaches a temperature between 200 to 240°C. There are two roasting methods:
- Dry pop
During this process, the roasting of the corn is done by means of hot air and the corn is covered with melted sugar or salt, afterwards.
- Wet pop
During this process, oil is added to the corn. This oil ( generally coco or soy oil) ensures an equal distribution of the heat during the roasting. And if sweetened popcorn is being produced, the sugar is already added before the roasting, so it can melt onto the popcorn during the roasting.
The unroasted corn can be wrapped in bags and placed in boxes after a temporary storage, without any further adjustments.
To the bags for microwave popcorn, also salt or sugar, soy oil or aroma’s are added, to create the same effect as obtained during wet popping. The microwave bags are airtight, to prevent decay due to the moisture in the air.
It is important that the unroasted corn does not dehydrate, because the grains need to have enough fluid inside to be able to pop.