Fruits and vegetables are extensively processed and the residues are often discarded. However, due to their rich composition, they could be used to minimize food waste. This study aimed to develop food products based on the solid residue generated from the manufacture of an isotonic beverage. This beverage was produced based on integral exploitation of several fruits and vegetables: orange, passion fruit, watermelon, lettuce, courgette, carrot, spinach, mint, taro, cucumber and rocket. The remaining residue was processed into flour and its functional properties were evaluated. The fruit and vegetable residue (FVR) flour was incorporated with different levels (20 to 35 %) into biscuits and cereal bars. The proximate composition, microbiological stability until 90 days and consumer acceptance were analyzed. The FVR flour presented a higher water holding capacity than oil holding capacity, respectively 7.43 and 1.91 g g −1 of flour, probably associated with its high levels of carbohydrates (53 %) and fibres (21.5 %). Biscuits enriched with 35 % of FVR flour presented significantly higher fibre, ranging from 57 % to 118 % and mineral contents, from 25 % to 37 % than when only 20 % was added. Cereal bars presented about 75 % of fibres and variable mineral contents between 14 % and 37 %. The incorporation of FVR did not change the fat content. The microbiological examinations are within acceptable limits according to international regulation. The incorporation of FVR flour did not impair consumer acceptance, the sensory attributes averaged around 6. The chemical, microbiological and sensorial results of the designed products attested for an alternative towards applying and reducing agro-industrial wastes.

Edible films were developed from the solid residue of the processing of whole fruits and vegetables. The solid residue, processed into flour (FVR flour) was chemically and structurally characterized by microstructure, elemental composition, structural links, and moisture sorption isotherm. Films were prepared by casting using aqueous extracts of 8% and 10% of flour (w/w) and characterized in terms of thickness, water solubility, mechanical properties, water vapor permeability, and Fourier transform infrared (FTIR). The analysis of microstructure and elemental composition, performed on flour (mean particle size 350 μm), showed an essentially granular aspect, with the presence of fibrous particles having potassium as one of the most abundant elements. FTIR results showed similarity between the characteristic bands of other raw materials used in edible films. The sorption isotherm of FVR flour showed a typical profile of foods rich in soluble components, such as sugars. Dried films presented an average thickness of 0.263 ± 0.003 mm, a homogenous aspect, bright yellow color, pronounced fruit flavor, and high water solubility. The FTIR spectra of the edible films revealed that addition of potato skin flour did not change the molecular conformation. Moreover, the films presented low tensile strength at break when compared with fruit starch-based films.

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In order to quantify antioxidant capacity in food products, several methods have been proposed over the years. Among them, DPPH radical is widely used to determine the antioxidant capacity of different substrates. However, it is known that different types of extractants, providing different responses, can extract a variety of bioactive compounds. Besides, storage time seems to interfere in the stability of these substances. Integral use of fruits and vegetables has been proposed along the years as a means of reducing environmental pollution and give a better destination to by-products from food industries. Thus, this study aimed to evaluate the antioxidant potential of a fruit and vegetables residue flour (FVR) with sequential and non-sequential extraction, in order to evaluate its antioxidant activity and phenolic compounds. And these compounds stability during storage of 180 days. It was observed that in non-sequential extraction, water was able to reduce by 74% the radical; however, at sequential extraction process, using six different extractors, each one was able to reduce at least 40% of DPPH. The total soluble phenolic contents in sequential extraction were 22.49 ± 1.59 mg GAE/g FVR on the first day and 5.35 ± 0.32 mg GAE/g FVR after 180 days.

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This study demonstrated the potential of FVR flour for edible coating and film formulation. Practical application on acerolas constituted a motivating route to evaluate and optimize this process; however, microbiological and sensory analyses are necessary to assess the material acceptability and safety.