High Added Value Products from Agroindustrial Residues: Study on Microfibrillated Cellulose for Food Applications

Waste composition range from simple sugars to complex polysaccharides such as starch, cellulose, and hemicellulose, including more complex sources such as lignin, lipids, and proteins. This composition suggests its use as raw materials that can potentially be valued by different techniques and used as resources for new food additives, leading to economic and environmental benefits. In this work, the extraction and production of microfibrillated cellulose (MFC) as the way forward to valorise agroindustrial residues. The high surface area and aspect ratio, rheological behaviour, water absorption and absence of cytotoxic and genotoxic properties of MFC studied in the present study facilitate its use in food applications as stabilizing and texturizer agent. This work has two main goals: The first goal is the production of MFC using a method based on the combination of green chemical and mechanical pre-treatment of the feedstock followed by a disintegration process of the cellulose obtained from agroindustrial residues. The results revealed that the different MFC obtained have a quality comparable with commercial MFC, which is reported by the determination of the Quality Index (QI). QI values between 50 and 63 are obtained with the agroindustrial subproducts tested. The MFC was also characterized using several techniques such as FTIR, SEM and TGA. The second goal is the MFC validation as thickener agent in food (mayonnaise, peach nectar, strawberry syrup and puree apple). First, a rheological study was carried out to observe the MFC thixotropic behaviour. Second, to evaluate techno-functional properties in-vivo, MFC was compared in terms of functionality with the seven additives commonly used in the industry: tare gum, xanthan gum, guar gum, carrageenan, pectin, agar and gelatine. The results revealed that the sample with 0.1% MFC exhibited a reduced thixotropic behavior compared to the other samples (1, 1.5 and 2%). Compared with commercial gums, MFC exhibits the highest water activity (0.87 ± 0.00) and the most alkaline pH value (10.10 ± 0.01). In the in vivo dietary models, thermal stabilization values after 15 min at 85 °C indicate that gums perform better than MFC and carrageenan in mayonnaise stabilization. This study also reveals that gums are more effective in stabilizing the cloud, while gelatine or MFC-containing samples exhibit a higher cloud volume after 30 min of stabilization. Notably, the cloud suspension of peach nectar with MFC-containing sampl