Worldwide more than 40% of the vegetables produced ends up as waste. In white asparagus production, the overall wastage can even go up to 55%. Effective valorization of this waste stream, including lower stem, peels, misshaped and damaged spears, will promote full crop use and close the cycle of our food production chain. A potential application of this source is in the production of dried foods. The dried asparagus powders available to the food industry, however, present poor retention of key flavour components and artificial flavours are added. Therefore, the objective of this research is to redesign the commercial drying process that will result in a higher quality dried asparagus powder without added artificial flavours.

Approach

Different drying methods will be applied, including freeze-drying, tray drying and spray drying. Asparagus buds (see figure 1) will be dried as a whole, in addition, split-stream processing will be investigated in which the juice and fibrous fraction are processed separately and recombined later in the process. It is hypothesized that the juice fraction will contain the most important precursors for the key flavour components. The juice fraction will, therefore, be spray dried and the fibrous fraction will be dried via the conventional tray drying method. White asparagus is selected as demonstrator crop in this project, but also other vegetables e.g. tomato and bell pepper are in scope.

Figure 1 Conversion of raw material into high-end products

This project is in collaboration with the PhD project at the laboratory of Plant Physiology which aims to unravel the flavour formation. Consequently, samples prepared in our lab will be analysed with GC-MS and LC-MS at Plant Physiology. Other partners in the project are ISPT, Unilever, Teboza, Coöperatie DOOR and TNO.