Wageningen Food & Biobased Research (WFBR) is developing an applied research project that will focus on the valorization of industrially produced pomace streams from different crops. In various agro-food production chains, pomace is a byproduct considered of very limited value and currently underutilized, despite containing valuable components with unique functionality.
The rich composition of pomaces evidently calls for higher value application and the material is potentially food-grade, thereby making a biorefinery of the material with loops back into the food chain is a viable option. Next to pomaces, fruit stones and peels can likewise be valorized for food or non-food applications. Components such as lignin and carbohydrates (e.g., cellulose and pectin) offer a wide range of applications. This would increase the value of the material and at the same time reduce the overall environmental footprint of the whole chain – circular; a win-win scenario.
Current status of pomace valorization
In the processing of olives, fruits, tomatoes, grapes and other crops, these pomaces are produced and generally consist of 20-30% of the weight of the raw material. The pomace is generally produced in large volumes at a central location, has a limited shelf life and contains a lot of water. Primary outlets are animal feed and landfill– hence, higher value applications are pursued. Several studies have been performed that focus on specific types of pomace and specific potential outlets, for examples pectin from apple pomace or valorization of tomato pomace to various outlets (Refresh project 2018). Additional technical development is still required to make the step towards industrial application.
There is a huge potential of pomace from various sources. All pomaces share a number of challenges, mostly the high-water content, short shelf life and complex matrix. When zooming in, pomace in fact always consists of three mayor constituents: skin, stones and flesh. These three major constituents can be valorized in separate routes. Stones contain oil, lignin, cellulose and protein. Skins contain pectin, cellulose and secondary metabolites, while flesh contains specific functional carbohydrates. Independent of the pomace source, generic technology is required to address the challenges highlighted above.
The separate fractions can be further valorized in specific value chains to match the specifications and needs of the end-users. Depending on these needs, specific downstream processes will be designed.
Envisioned pomace valorization routes
To develop viable sustainable pomace valorization routes WFBR is developing a public Private Partnership Project sponsored by the Dutch TKI-Agri-Food.
Some pomace streams have a high content of stones (e.g., olives, peaches and cherries) and these will be valorized focusing on lignin, cellulose, oil and protein extraction.
Pomace with a lower stone content, such as tomato pomace, will be valorized via separation of the major constituents and subsequent production of oil and protein from seeds and carbohydrates and secondary metabolites from the skins.
Pomace that consists mostly of flesh, such as apple pomace, will be valorized focusing on the specific carbohydrates. For all pomaces common issues such as shelf life, water content and preservation need to be addressed.
In all of these routes, the aim is the total use of the pomace for a proper valorization. The extraction of certain components will impact the quality of the components that remain in the pomace. Therefore, to preserve the integrity of the valuable components in the downstream process, a smart choice in the extraction route is key in designing an effective process for the valorization of each type of pomace. Moreover, the selected sequence of unit operations should take into consideration the uniqueness and the physiological characteristics of each pomace.
Impact on the footprint of the whole chain
Nowadays, pomace is mainly discarded as landfill, digested to produce biogas or directed towards animal feed. The footprint that these outlets generate on the whole chain can be significantly decreased by creating a better valorization of the specific components that can be isolated from the material. The impact on the footprint will be part of the project.
WFBR is looking for partners to support this promising development. Our aim is that all partners benefit from the research and provide additional value for society and companies. Are you a supplier of pomace, technology provider or user of functional fractions and ingredients (Food and non-Food)? Than this is your chance to collaborate with us and other committed stakeholders in the value chain and decrease your environmental impact while developing novel business opportunities.