Impact of Protein- and Polysaccharide-Based Edible Coatings and Citric Acid as a Natural Antioxidant on the Quality Parameters, and Image Analysis, of Freeze-Dried Jerusalem artichoke (Helianthus tuberosus)

The aim of this study was to evaluate the effects of protein-based (zein) and polysaccharide-based (carboxymethylcellulose, CMC) edible coatings and citric acid (CA) applied prior to freeze-drying on the quality parameters of Jerusalem artichoke (Helianthus tuberosus L.) slices from ‘Albik’ and ‘Rubik’ cultivars. Freeze-drying increased inulin extraction efficiency (57–61 g 100 g−1 vs. 44–45 g 100 g−1 in fresh samples). In the ‘Albik’ cv., CMC and CA coatings significantly minimized L-ascorbic acid losses, with a 10–20% reduction vs. control. For the same cultivar, enhanced polyphenol retention was observed (up to 13%) when CA coating was applied, while the use of zein reduced vitamin C content in both cultivars. Sensory analysis (PCA, 92.4% variance) revealed that CMC improved appearance, texture, and overall acceptability, while zein imparted an off-taste, odor, and fragility. Image texture analysis showed elevated parameters (e.g., HMean) post freeze-drying, with CA inducing the greatest structural changes and zein yielding samples most similar to raw material. Machine learning classification (quadratic/linear SVM, 10-fold CV) achieved 91.5% (‘Albik’) and 81.9% (‘Rubik’) accuracy, perfectly distinguishing raw slices (100%). These findings demonstrate that CMC and CA coatings optimize bioactive retention, sensory quality, and textural differentiation in freeze-dried Jerusalem artichoke, supporting their application in functional food production.