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Fresh-cut leaf vegetables, salad
Recent research shows that most people eat too little vegetables and fruit. To stimulate their consumption for example vegetables and fruit salads are made. These salads contain fresh vegetables and/or fruit and are easily used. These products are already processed by the producer and are ready to be eaten. In processing the vegetables and fruit it is important that the natural characteristics like crispness, color, aroma
and taste are preserved.
The vegetables that are delivered are often manually pretreated. In this pretreatment the bruised parts, the outer leafs of for example lettuce, and extraneous matter like leafs of carrots and leek are removed.
Removing the heart of lettuce
In the processing of lettuce and cabbage the heart is removed. The heart is very hard and has a different taste. It can be removed manually as well as mechanically. When this is done mechanically the head is placed in a holder. The heart is cut off the head by means of a knife in the shape of a funnet.
Afterwards the vegetables are cut in the desired size. The cutting process can happen both manually and mechanically. The vegetables can be cut mechanically by transporting them through rotating knives. It is important that the knives are very sharp. When the knives are sharp the cutting surface is better which damages the cells less. Damaged cells may decay.
The cut vegetables have still to be disposed of sand. The vegetables can be washed by flotation, drums or crate washing (with smaller amounts).
When the vegetables are washed by flotation they are brought into a container with water. Extraneous parts are removed from the vegetables by the current. In order to cause more friction, air is brought into the container from the sides. During the washing process the sand sinks to the bottom while lighter particles start floating. These floating parts can be removed with a flycathcer. A flycatcher is a circle with the same width as the washingunit and it contains large openings. The circle turns on the surface of the water and takes up the light particles. When the ligth particles are in the circle they are transported to the side, outside the washing unit. Flotation washing can happen in a continous process. In drum washing the vegetables are put into a big drum. The drum is partially put under water. When the drum is turned the vegetables are rinsed due to the friction with the water, the sides and the friction between the vegetables themselves. Brushes can be applied in the sides of the drum to increase the friction. Drum washing is especially fit for solid vegetables. In crate washing the vegetables are put in the crate in a tank
with water. Due to the current of the water the vegetables are washed. With crate washing smaller amounts of products are washed.
To improve the storlage life and quality of the vegetables they are lightly dried. The drying process can happen by centrifuging, vibrating or vacuum drying.
Centriguging means that the vegetables are put in a drum or in a special crate centrifuge. Because the drum rotates very fast the water is hurled outside through a perforated side.
By knocking one knocks of the water from the vegetables. Via an open conveyor the water is further drained away.
By vacuum drying the water is sucked from the vegetables.
In a salad several kinds of vegetable are often mixed. Mixing can happen in a drum with edges in its sides. The vegetables are mixed when the drum is turned with the desired amount. Mixing can happen in batch or continuous.
Normally vegetables are packed in plastic bags. The desired amount is put into bags and the bags are sealed afterwards. The packing happens ofen with a specific gas composition, which increases the storage life. It is important that the gas composition contains a limited amount of oxygen. A lower percetage of oxygen than is in the air increases the storage life. Packing without oxygen causes decay. The vegetables still breath and need oxygen. When vegetables are vacuum packed the crispy structure is damaged.