Optimized production of plant-derived juices and purees with minimal impact on quality aspects

Project Details


Main research question/goal
The aim of this project was to develop new technological possibilities in the production of juices for Flemish fruit and vegetable processing companies. The aim was to increase the quality (taste, color, etc.) of their current products (juices) or to develop innovative products (new recipes, nutrient preservation, textures and more). In doing so the companies will differentiate their products from their competitors. Specifically, by optimizing the various state-of-the-art process steps (and their connection), juices or purees can be produced with maximum quality retention. The project is carried out in close contact with a group of interested companies. They have chosen to focus on apple juice and kale puree.

Research approach
This project differs from other research projects by studying combinations of process technologies. The researchers use Inert Gas (IG) milling and Low Oxygen (LO) pressing in combination with High Hydrostatic Pressure (HPP), Pulsed Electric Field (PEF) and Radio Frequency (Pasteurization) as  conservation technologies. The IG-LO technology is optimized for both types of end product (apple juice and kale puree), HPP and PEF for apple juice and HPP and RF for kale puree. After the optimization step, IG-LO technology is combined with the pilot scale pasteurization technologies per product. The novel conservation technologies are compared with conventional thermal pasteurization. Additionally, a cost-benefit analysis is carried out, which enables the companies to immediately assess the economic viability of these technologies.


Although several initiatives were started in recent years to bring targeted knowledge development and dissemination on the use and application possibilities of innovative grinding, pressing and preserving technologies to food companies, their industrial implementation remains limited in Flanders. In the meantime, the results of HighQJuice project are available. For the apple juice, the combination of spiral filter press and classic thermal pasteurization resulted in a nice bright yellow color that was preserved during storage. Just like the PEF treatment, the classical thermal pasteurization resulted in a good inactivation of the PPO and POD enzymes. That was less the case with the HPP treatments. PEF treatment in turn resulted in the highest Vit C content in the juice. The juice stability in the HPP treated juices was also less good due to residual PME activity during storage. In summary, it can be said that the combination of spiral filter press and classical thermal pasteurization is the best combination for the production of long-lasting juices.


For the kale, different process intensities of a traditional thermal treatment were compared with an RF treatment. Through analyses of color, texture, taste and enzyme activity, the impact of the processing was mapped. The most intensive classical heat treatment at 128 °C resulted in the least attractive puree. There was little difference between treatment at 90 °C with the traditional approach or via RF, only some differences were measurable in the aroma profile.

The Flemish fruit and vegetable processing companies now have more concrete process information at their disposal to tackle the targeted production of juices and purees, with maximum quality retention (taste, color, etc.). Product differentiation through the use of new technology is within reach.

Effective start/end date1/10/1630/04/19