A portion of the water is removed from the fruit as it evaporates. The concentrated juice can be considered a concentrated sugar acid solution. With this in mind and the low pH of the fruit, the puree and juice concentrates are not suitable as substrates for bacteria that are potentially harmful to human health.
There are basically two concentration systems:
The thick stock and the syrupy juice are concentrated by a Fruit Juice Production Line forced circulation evaporator in which the product is forced to be heated by a tubular heat exchanger by a suitable centrifugal circulation pump to release water vapor in the evaporation chamber.
The evaporator is a multi-effect system under vacuum, in which the steam produced in one effect is used for the next effect of protecting the product and generating new steam, starting from the highest temperature allowed by the product, up to the lowest temperature, usually At around 42 - 45 °C. The system also has the advantage of significantly reducing active steam consumption.
For clear juice, the evaporator is always multi-effect, but the so-called "falling film type" in which the product flows rapidly along the wall of the vertical heat exchanger, which wall is heated in the outer casing by steam from the previous effect. The advantage is that the heating rate is very fast, the residence time in the evaporator is shorter than that of the forced circulation type, so the product quality is better maintained.
In connection with the evaporation process, it is possible to retain the volatile aroma of the fruit which would otherwise disappear in the condensed water.
Only fresh juice, not rotten fruit, produces a good aroma. If rotten fruit is used, the amount of ethanol in the aroma will increase rapidly, resulting in a decrease in quality.
In order to obtain the fragrance, the secondary condensate is recovered from the evaporator and sent to the aroma recovery plant.
The unit consists of two main components: a boiler, condensate from the evaporator is heated in the boiler to produce steam, and a fractionation column for separating the vapor into an aromatic concentrate and a poor aromatic stripping liquid. The system concentrates the aroma in a ratio of 1:150 - 1:200 compared to the condensate feed. The aroma storage must be placed at low temperatures.
Storage of semi-finished fruit
Storage of semi-finished fruit can be carried out in a 200 microliter volume box by the following procedure:
The product is sterilized by tube-in-tube heaters prior to packaging for use in sauces, paste products or plate heat exchangers to prevent clear or turbid juices, provided that the fiber content is less than 5%.
Heating is done by superheated water, rather than direct live steam to avoid thermal stress. Tube-in-tube technology provides uniform and reasonably fast heating because the product flows in a thick film, allowing "two sides" for heat exchange.
After cooling, the sterilized product is sent to a dedicated filling machine with one or two filling heads. The filling head depends on the required output to fill the multi-layer bag in a controlled real-time steam environment, avoiding the environment. Pollution.
Fruit processing obviously depends on the rows of materials and the desired end product.
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