The production of high quality juices or juice concentrates from coloured fruits is a complex task with a multiplicity of parameters which have an effect on the final quality. atech innovations gmbh, a German manufacturer of ceramic membranes, and the Swiss engineering company Unipektin AG have developed a filtration process by which intensely coloured juice concentrates with stable clarity can be produced from coloured juices. The new process not only improves the product but also provides savings in production costs.
Amongst other fruits, blackcurrants, redcurrants, raspberries, sour cherries, strawberries and elderberries are used for the production of coloured juices. The juices won from these fruits are used predominantly for mixed drinks such as apple/cherry, in red lemonade, as colourant in other foodstuffs or in functional drinks. Furthermore the physiological effectiveness of the ingredients is highly valued for e.g. its tumour-inhibiting, cardiovascular-stimulating and cholesterollowering characteristics. The colour of coloured juices and concentrates made from them is a desired quality characteristic. It should be characteristic of the fruit, intense - and in regard to storage - stable. Browning caused by oxidation lowers the quality. The often expensive raw material demands an especially costeffective juice recovery and thus a successful synthesis of quantity (juice yield) and quality (colour yield and colour stability). For predetermined raw material and plant technology the processing parameters, mechanical stress and thermal and enzymatic treatment are variable and can be adapted to the respective fruit. All measures are aimed at winning sufficient juice with the best colour yield from expensive raw material without endangering the subsequent juice stability with excessive extraction methods.
The Use of Ceramic Membranes in the Fruit-Juice Industry to produce intensely coloured, brilliant and stable juices