Plant-derived biopolymers, such as cellulose, starch, lignin, pectin, are interesting because of their wide availability. Other than virgin vegetation or crops, a source of biopolymers can be represented by food waste. Fruits, vegetables, roots and tubers constitute half of all wasted food. Turning this organic waste into raw materials for bioplastics has a positive environmental impact: reduced CO2 release from food disposal, drop of fossil fuels consumption, and less non-biodegradable polymers dispersed into the ecosystem. The usability of biopolymers as processable and stable matrixes forming films for packaging or bags is nontrivial. Obtaining pure biopolymers from food waste is extremely challenging since their strong interconnection and crystallinity, requiring time and multiple and costly purification steps. Furthermore, the waste is a complex and variable mixture of different plants and fruits each with a specific composition and hierarchical organization. A more recent and cost-effective approach has been the use of non-treated, whole plant waste powders as raw materials, which are then hydrolyzed and/or thermally treated before film casting. Avoiding the extraction step allows not only to save time and money, but also to directly create a composite material, retaining all the macromolecules originally present in cell walls and potentially exploiting all their peculiarities. In order to optimize and generalize this approach it is fundamental to have a simple and fast routine to determine the composition of the vegetable waste. In this perspective, it is important to notice that all plants and fruits share the same six basic components (the big six): cellulose, hemicellulose, pectin, lignin, polyesters and starch. Thus, a simple classification of the waste can be done just determining the quantity of the big six. In this contribution, we will report on the algorithm we are developing combining 13C CPMAS NMR and 1H TD NMR for a fast determination of the vegetable waste composition based on the spectral properties of the pure components (Figure 1).

Development of a method to determine the composition of vegetable waste based on NMR

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