Introduction

Fruit juice concentrate plays an important role in making different juice products. As an essential raw material, it have huge impact on juice quality. This passage introduced the most common ways to make fruit juice concentrate, including vacuum concentrate, freeze concentration, membrane concentration and aroma recovery. By comparing these fruit juice concentrate process technology, we can figure out their advantages and weakness, so as to apply them better in juice processing.

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concentrated fruit juice

What is fruit juice concentrate?

Fruit juice concentrate is made by removing water from freshly squeezed fruit and vegetable juice. It is usually used as base stock for various food products. With less volume, it contains soluble solids of 65%-70%. Fruit juice concentrate process is a effective way to reduce packing and transportation cost. And it guarantee the consistent quality of end products. Meanwhile, with the increase of sugar and acid content, it is in favor of preservation.

To choose suitable concentration technology, quality must come first. Qualified fruit juice concentrate must retain similar color, flavor and nutrition as original fruit juice after diluted. In this regard, the concentration process must be carried out under low temperature. The most popular fruit juice process technology are vacuum concentrate method, concentration by refrigeration, membrane technology concentration. Besides, in fruit juice concentration process, aroma recovery is an influential step we can’t ignore.

fruit juice concentrate process

Vacuum concentrate method

Vacuum concentration requires heating fruit juice under low pressure so as to reduce the boiling point and let the water content evaporate rapidly. Vacuum concentration equipment is the most important and widely adopted device in fruit juice concentrate process. It can be classified into single-effect and multiple-effect concentrate device. Based on the heater structure, it includes central circulation tube evaporator, coil evaporator, rising film evaporator, falling film evaporator, plate type evaporator, scraper evaporator and centrifugal film evaporator.

Take vacuum film concentrator for example. The temperature is lower than 30-40e, sometimes even as low as 22-25e. As for heat pump concentration system, it uses the heat generated by refrigerator as heat source, and inflated refrigerants as cooling agency, representing higher heat utilization. Under the condition of high vacuum degree, the concentration temperature is lowered to 15-20e, which can protect the quality of concentrated juice.

The heat required by evaporation and concentration comes from primary steam and secondary steam. The former one is called single-effect evaporation, during which the secondary steam is condensed directly rather than used for heating. If the secondary steam is used for another heating, this process is called multiple-effect evaporation. Generally, fruit juice concentrate goes through 1-5 times evaporation, with the solid content raised up to 70%-72% from 5%-15%.

vacuum concentrate

Characteristics of vacuum concentrate

As fruit juice concentrate is conducive to storage and transportation, it is in growing demand in juice processing industry. Vacuum concentrate method can shorten the process time and preserve the fruit juice quality at the same time, compared with high temperature and normal temperature concentration. The general temperature for vacuum concentration is 35℃, the vacuum degree is 94.7Kpa. To prevent microbe production and enzyme activity under this favorable condition, we need pasteurize it ahead of time.