Citation: Machado, J.S.; Pieracci, Y.; Carmassi, G.; Ruffoni, B.; Copetta, A.; Pistelli, L. Effect of Drying Post-Harvest on the Nutritional Compounds of Edible Flowers. Horticulturae 2023, 9, 1248. https://doi.org/10.3390/ horticulturae9111248 Academic Editor: Michailidis Michail Received: 31 October 2023 Revised: 13 November 2023 Accepted: 17 November 2023 Published: 20 November 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). horticulturae Article Effect of Drying Post-Harvest on the Nutritional Compounds of Edible Flowers Jean Santos Machado 1,2 , Ylenia Pieracci 3 , Giulia Carmassi 1 , Barbara Ruffoni 4 , Andrea Copetta 4, * and Laura Pistelli 1,5 1 Department of Agriculture Food Environment, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy; jeansmachado@ufpr.br (J.S.M.); giulia.carmassi@unipi.it (G.C.); laura.pistelli@unipi.it (L.P.) 2 Postgraduate Program in Sciences (Biochemistry), Federal University of Paraná, Av. Cel. Francisco H. dos Santos 100, Curitiba 81530-000, Brazil 3 Pharmacy Department, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; ylenia.pieracci@phd.unipi.it 4 CREA—Research Centre for Vegetable and Ornamental Crops, Corso Inglesi 508, 18038 Sanremo, Italy; barbara.ruffoni@crea.gov.it 5 Interdepartmental Research Center, Nutraceuticals and Food for Health, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy * Correspondence: andrea.copetta@crea.gov.it Abstract: The post-harvest techniques are the most critical point to ensure the quality of edible flowers (EFs) and to keep the bioactive metabolites available for human nutrition. The different species of EFs also represent a problem in improving their consumption with safety. The present study focused on the description of the effects of the commonly used drying treatments in the phytonutritional composition of four species of EFs, Callianthe megapotamica, Callianthe striata, Nemesia strumosa and Salvia elegans. The bioactive metabolites and antioxidant activity were determined after freeze-drying (FD) and hot-air-drying (HA) treatments in comparison to fresh flowers. All EFs showed different mineral/trace compositions with potassium as the main element and 70–86% water loss. Both post-harvest treatments increased all the metabolites and antioxidant activity in each species. C. striata with FD treatment had the highest content of primary and secondary metabolites. N. strumosa has the highest ascorbic acid content with the HA treatment. All species had significant antioxidant activity, increasing with FD for C. striata while HA is more recommended for the other species. The post-harvest techniques are able to preserve and increase the bioactive metabolites and must be chosen according to each EF species. Keywords: Abutilon; antioxidant activity; Callianthe; Nemesia; polyphenols; Salvia 1. Introduction Complete edible flowers (EFs) or their parts, commonly the petals and sepals, have been used since ancient times around the world to add color and flavor to various food preparations. They can be enjoyed fresh, either on their own or incorporated into salads and desserts [1]. In addition to their visual appeal, EFs boast a rich phytonutritional composition that includes minerals, vitamins, proteins, carbohydrates, polyphenols, pigments and a low fat concentration. All of these components contribute to a natural and healthy nutritional profile [2,3]. The different species of EFs have different phytochemical composition, for example, the pansy has greater quantities of water, proteins and dietary fiber in its tissues than the snapdragon [4]. The global market of EFs is promising and attractive with a great potential to increase in terms of horticulture farms, traditional producers and the food industry, as well as to enhance the visual aspects, nutritional aspects and quality of human food consumption [2,3]. All over the world, the EFs that can be purchased in the supermarket are those deriving from annual or perennial herbaceous plants that can easily be grown in pots; however, Horticulturae 2023, 9, 1248. https://doi.org/10.3390/horticulturae9111248 https://www.mdpi.com/journal/horticulturae