Sugar reduction in fruit juices

New process for the production of apple juice with reduced sugar content (-30%)

No biochemical transformations of sugars and no byproducts. The juice remains naturally. The process is based on the following approaches (see also Fig.1)

In apples, both the sugar content and the varieties of sugars are not distributed homogeneously. In the upper layers of the fruit body below the peel, the sugar content is noticably higher than in the layers below. It is also known that the apple peel contains most of the valuable substances, like polyphenols.

The first step during juice production is the separation of peel from the fruit flesh, to ensure that essential plant substances are not removed together with sugars in the consecutive steps. The peel can be separated from the flesh simply by using a technical peeling machine. Only a part of the total amount of the apples is processed in this step. In addition, only a specific fraction of the fruit flesh is used for the partial removal of sugar.

After conventional pressing of a specific part of the fruit-flesh, sugar is removed from this pressing juice via nanofiltration/diafiltration and remains in the concentrate.

The remaining peel and fruit flesh (core) are pressed together with untreated apples conventionally. This fruit juice is mixed together with the permeate of the nanofiltration (almost sugar free juice fraction). The resulting mixture is further treated conventionally to produce an apple juice of marketable quality.

In an optimized process, only around 40 % of the raw material (apples) need to be peeled and only around 30 % of the fruit-flesh (juice) is used for the separation of sugars. All kinds of apple juices (juices from concentrates, direct pressed clear juices and cloudy apple juices) can be produced based on this patented technology. According to Fig.1, with the new process the changes in phenolic compounds, flavours, acids, vitamins and minerals will be only around 10 - 15%.

The process has been tested in an industrial scale and samples are available upon request. Based on specific assumptions (production capacity 1,000,000 liters per year), the production cost increases around 5 % only.

Fig. 1: Process for production of apple juice with reduced sugar content.
Fig. 1: Process for production of apple juice with reduced sugar content.

Mechanical separation of valuable substances

Six main fractions/compounds can be considered.

peeling the apples

Most of the valuable substances, like polyphenols, vitamins etc. are preferably found to be in the peel. In the new process 100% of the apple peel are conventionally used in the juice production (see Fig. 1).

Pressing of apple flesh and nanofiltration (NF) of the flesh juice

peeled apple
apple juice

Using a nanofiltration for the separation of sugars, the following behavior can be expected.

Fig. 2 Separation characteristic of nanofitration
Fig. 2 Separation characteristic of nanofitration