September 19, 2014
Updated March 2016
Lime oil is extracted from limes, the member of the citrus family. A large variety of limes are used for this. The better known varieties are Persian, Mexican, Key, and Tahitian Limes.
The production of lime oil is highly developed in Mexico. The industry is strong with Persian Limes in Veracruz state; Mexican and Persian Limes in Colima and Michoacan states; and lemons in the northeast Ciudad Victoria – Montemorelos area.
Traditionally, the industry has been centered in Tecoman in the State of Colima. However, a combination of HLB – the deadly citrus disease also known as Greening – and poor cultural practices have reduced the grove acreage to 20,000 hectares. The State of Michoacan, centered around the city of
Apatzingan, has taken the lead from Colima. They currently have maybe as much as 90,000 hectares of limes, with freshly planted groves in ample evidence.
Most of the fruit goes to the fresh fruit market. Nevertheless, packing house culls are still the lesser part of the fruit going to the oil recovery plants.
Typically distilled oil is produced. The process for producing this lime oil involves first washing the fruit. Next it goes to small expeller presses which crush the fruit and expel the juice, along with the oil. These expeller presses, known as "molinos", have continuous flighted tapered screws. Originally supplied by Brown International, the machines have gradually been improved on by Mexican manufacture.
Currently the molinos have a 7" diameter inlet, and the crushed skins and pulp come out through a 3" opening. The screws, which turn at 650 rpm, are driven by 20 hp motors.
The skins and pulp from the molinos can be fed to Vincent screw presses for further oil recovery.
Distilled oil is recovered from the liquid separated by the molinos and Vincent presses using pot stills (also called calandrias, "alambiques" in Spanish). These are built to hold a batch of 100 to 1500 gallons. They are simply stainless tanks where the juice is heated by steam. The temperature is raised to about 100C, after which the steam flow is backed off so as to maintain a level in the pot still.
The evaporated vapors flow to a condenser. This is a smaller tank, with water coils used to condense the oil and water. This condensate flows to a conical separation tank with the small end at the top. The oil floats to the top, and from there it goes to 55 gallon drums. Currently this distilled oil is going for $35 per kilo, on up.
Many years ago Vincent sold these pot still systems, especially in Haiti. The industry there is now defunct.
Processing a batch in the pot still takes several hours. Once the oil has been driven off, the remaining juice is drained off. Because it is a hot acid, stainless or fiberglass is used.
At some plants this juice is sent to a TASTE evaporator for the production of lime juice concentrate. At small oil plants it is simply sewered.
Some of these same lime processing facilities also produce cold pressed oil. Juice can be extracted prior to crushing the fruit. This juice is processed through bowl centrifuges to separate the cold pressed oil. (The remaining juice is made into concentrate using a TASTE.)
The second important source of income at an oil plant is the lime peel. This is the residue from juice and oil extraction. This peel is washed to remove the sugars, pressed to remove free water, and then dried at low temperature. The dried peel is the raw material used for pectin production by food ingredient firms such as CP Kelco, Cargill, DuPont, and FMC. The spot price paid for this peel has recently been in the range of $1,800 to $2,000 a ton.
Some of the Mexican oil plants have their own equipment for washing and drying the peel. However the small ones sell the peel, still wet, to washing and drying operations owned by the pectin producers. In the 1960's Vincent was an early developer of these wash & dry lines, working with Copenhagen Pectin (today CP Kelco).
Screw from Molino Type Press