Gherkin

The fruits of the pickle have an average length/thickness ratio of about 3:1. They are more or less long and triangular in shape. In general, preference is given to smooth fruits, without spines and with a uniform color.

The pickle is indigenous to warm regions. The annual plant can form up to 3 meters of long square-shaped stems. In Western European greenhouse agriculture these stems are forced to grow around tensioned wires.
The flowers are unisexual. Historically, cross-fertilization was needed, but nowadays there are parthenocarpic varieties, which can bear fruit without pollination. The pickles will contain little to no seeds.

The pickles are sorted as follows:

The world's largest pickles are used to make so-called ‘sour bombs’. Moreover, the pickle can be seen in the form of a rolmops, a rolled herring containing a pickle.

Pickle production

Harvesting

Pickles are able to grow in any type of soil, provided that the soil structure and the water supply are sufficient. Preference will be given to well-drained soil with a high humus content.
Cultivation may take place in the garden or in a greenhouse. The yield of a greenhouse grown crop is 5 to 10 times higher than crops grown in regular soil. Moreover, the fruits can be harvested in a greenhouse from July to October. However, the majority of the pickles is grown outside of greenhouses.
Regular picking is important, stimulating the plant to produce new fruits. When the pickles grow larger, more energy is required from the plant. This will reduce the number of pickles that can be harvested.

Processing

The processing of the pickles can be done in two ways. These two methods will be discussed separately.

Processing into sweet and sour pickles

For the production of sweet-sour pickles, pickles from the categories A to C are used. When pickles from category E are being packed, the pickles are pierced in advance. This prevents gas forming.

First, the pickles are washed in brush washers or drum washers. After this, they are bottled in glass or cans, which have been treated with acid-resistant paint and already contain the necessary herbs, such as yellow mustard seeds, onion and bay leaf. After the filling of the pickles with the aid of a hand loading table or band filling machine, a covering liquid is added. This covering liquid consists of water, vinegar, salt, sugar and optionally aromatic spices. In order to avoid spoilage after opening, a small amount of preservatives may be added. The jars and cans are then sealed. The jars have ventilating lids, which are also acid resistant.

In order to fully conserve the product, it is pasteurized in a pasteurization tunnel. In general, pasteurizing is done at a temperature of 80 to 82°C. The pasteurization time can be controlled by adjusting the speed of the belt, so that sufficient microorganisms are killed and the product will remain crispy. After pasteurization the conserves are rapidly cooled.

Processing into salted pickles

When there is supply surplus of pickles, the excess pickles are fermented in large tanks, prolonging their shelf life. All pickles are washed before processing, just like the pickles that are processed into sweet-sour pickles. After this, the pickles go through a puncture machine, which punctures a number of holes into the pickles, ensuring that the salt is absorbed quickly into the pickles.

The pickles are put in tanks with about 6% of brine to ferment. The salt slows down the growth of undesirable microorganisms, while the lactic acid bacteria can continue to do their work. In addition, the salt triggers the cells to release their moisture and stimulates the growth of lactic acid bacteria, which uses the sugars from the cell fluid as a power source.

The fermentation can be caused by the lactic acid bacteria already present on the pickles, or by means of a pure culture. In case the pure culture method is used, the pickles first have to be washed with water that contains 100 to 150 ppm of chlorine, killing off any bacteria that are naturally present. This controlled fermentation enables better quality control of the pickles.

The fermentation lasts approximately up to 4 to 6 weeks, in which sugars are converted by lactic acid bacteria to lactic acid and carbon dioxide. This process produces 0.5 to 0.8% lactic acid. After fermentation, the salt content is increased weekly by 3% until a salt content of 15% has been reached, which, together with the lactic acid, ensures sufficient preservation.

The temporary preserved pickles are desalted before they can be processed further into sour pickles (see the first method) or piccalilli. Desalting is done by placing the pickles in running water for about two days.

Storing

The last step of the pickle production process is labeling the jars or cans, which then can be stored outside the refrigerator for a long period of time.

Food Safety & Hygienic Design

With products that have a relatively high acidity (pH < 4.6), microbial spores cannot develop into vegetative (alive) microorganisms that can grow and spoil or seriously contaminate the product. Sterilization, the inactivation of spores, is therefore unnecessary. Because of the use of an acidic covering liquid, a mild pasteurization is sufficient to kill off any vegetative cells, and combined with rapidly cooling of the product this also has less of an influence on the flavour.

The acidity level of the covering liquid or the combination of sour and salt in the salted pickles, only allow the acid-producing lactic acid bacterium to eventually develop. This makes the product more microbially stable from an earlier stage on.

The production equipment and machinery must be of a GMP-class. This means that the machinery and equipment must be visibly clean before use. In case that the machinery cannot be emptied fully (and set aside clean and dry), the machinery has to be thoroughly cleaned and disinfected before the production process can start again. Cleanable to a microbial level (hygienic design) is not necessarily required for this process. A light microbial contamination should not be a problem.

The washing off of the salt has to be done at a low temperature and with clean water. In case of recirculation, this part of the process must be hygienically designed.

After closing the packaging, the product undergoes a heat treatment. However, this is not a license to be less careful during the pre-processing phase or cleaning the processing equipment less frequently or not fully. Large amounts of heat-stable toxins, coming from microorganisms, may still be toxic after sterilization, and pose a threat to the health of the consumer.