Dear Colleagues,

In recent years, there has been an increasing amount of interest in recovering bioactive compounds from agricultural, forestry, and food industry wastes, aiming to reduce their environmental impact and simultaneously improve the sustainability of economy and society. The recovery of these compounds involves several steps, where the extraction technique is one of the most important techniques. Furthermore, due to their recognized health properties, such as antioxidant, antimicrobial, and anti-inflammatory activities, the recovered compounds can be incorporated in food, cosmetic, and pharmaceutical products, giving them an extra value.

Despite the large number of publications on the extraction of bioactive compounds from agro-food wastes, there is still a great deal of interest in the topic and a lack of papers regarding the incorporation of the obtained natural extracts.

This Special Issue welcomes research articles and reviews that could fill the gap between research and industrial applications, addressing the new advances in biowaste valorization for novel product application. Manuscripts devoted to the extraction of bioactive compounds from agro-food wastes and their chemical and safety characterization are also welcome. Particular attention will be given to manuscripts that demonstrate the application of the obtained extracts in new products and evaluate their effect.

An integrated approach to the challenge of sustainable food systems: adaptive and mitigatory strategies to address climate change and malnutrition (https://www.nibio.no/en/projects/systemic).

Dr. Manuela M. Moreira
Dr. Francisca Rodrigues
Prof. Dr. Cristina Delerue-Matos
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Foods is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• food waste valorization
• bioactive compounds
• green extraction techniques
• safety assessment
• food applications
• non-food applications

Title: Natural antioxidant extracts from vineyard pruning residues obtained by subcritical water extraction: bioactive composition and safety evaluation
Authors: Manuela M. Moreira1,*, Olena Dorosh1, Ana Margarida Silva1, Clara Grosso1, Elsa F. Vieira1, Francisca Rodrigues1, Virgínia C. Fernandes1, Andreia F. Peixoto2, Cristina Freire2, and Cristina Delerue-Ma
Affiliation: 1REQUIMTE/LAQV, Instituto Superior de Engenharia do Instituto Politécnico do Porto, Rua Dr. António Bernardino de Almeida, 431, 4249-015 Porto, Portugal 2REQUIMTE/LAQV, Departamento. de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal
Abstract: Biomass represents a natural source of valuable components with potential application in many industries. Recently, it has been demonstrated that vineyard pruning residues can be used as a potential source of bioactive compounds, namely polyphenols. In this study, a central composite design was used to optimize the total phenolic content and antioxidant activity (by FRAP and ABTS assays) of vine-canes from Touriga Nacional variety. Subcritical water extraction (SWE) was employed, and the independent parameters studied were extraction temperature (150-280 °C) and time (20-50 min). The optimal extraction conditions were 33 min and 280 °C, revealing a high total phenolic content (229 ± 23 mg gallic acid equivalents/g dw), as well as a high antioxidant activity by FRAP and ABTS assays (228 ± 20 and 236 ± 11 mg ascorbic acid equivalents/g dw, respectively). The optimal extract also displayed strong in vitro neuroprotective effects, inhibiting several brain enzymes involved in neurodegeneration: acetylcholinesterase (IC50 = 290.5 µg/mL), butyrylcholinesterase (IC50 = 244.0 µg/mL), tyrosinase (IC50 = 1459.0 µg/mL) and monoamine oxidase B (~53.4 % of inhibition at 1000 µg/mL). The phenolic composition determined by HPLC-DAD revealed the presence of compounds belonging to different families, with gallic acid (118 ± 6 mg/100 g dw), catechin (468 ± 23 mg/100 g dw) and quercetin (153 ± 8 mg/100 g dw) being the major contributors to the demonstrated antioxidant properties of the produced vine-cane extracts. The extracts were evaluated regarding the presence of 14 organochlorine pesticides and the absence of these compounds was confirmed. The results proved that SWE can be a useful extraction technique for obtaining phenolic compounds from vineyard pruning residues, which can be further safely applied to food or cosmetic industries creating an added value to this residue.

Title: From waste to resource: valorization of food manufacturing residues through engineered hydrochar and biochar for environmental and clean energy applications-A comprehensive review
Authors: Silvia Escudero-Curiel; Alba Giraldez; Marta Pazos; Ángeles Sanromán
Affiliation: Universidade de Vigo
Abstract: Agri-food residues or by-products have increased their contribution to the global tally of unsustainably generated waste. These residues, due to their physicochemical properties, are increasingly being recognized as valuable products within the principles of zero waste and circular economy advocated by different government entities. Consequently, they are utilized as raw materials in other industrial sectors, such as the notable case of environmental remediation. Thermochemical valorization of these residues yields carbonaceous materials known as hydrochar and biochar, which find efficient, cost-effective, and satisfactory results in applications in various environmental contexts such as removing pollutants from wastewater or green energy generation. Engineered hydrochar and biochar can be designed or tailored to enhance or improve their performance in these mentioned applications. This study aims to conduct a systematic review to synthesize the key characteristics defining these residues and their corresponding hydrochar and biochar. Additionally, the types of modifications implemented in recent years to enhance their capacity and performance for applications will be examined, along with providing future perspectives in this field based on the conducted review.