Heatmap and PCA-based evaluation of bioactive compounds and volatile profiles in aronia fruits under different drying methods

This study compares the bioactive compound contents and volatile profiles of products obtained from the 'Nero' variety of aronia (Aronia melanocarpa L.) fruits subjected to three different drying methods: freeze drying, vacuum drying, and hot air drying. Total phenolic content, total flavonoid content, and antioxidant activity were evaluated. The highest values were observed in the freeze-dried samples, with 67.9 mg GAEg-1 dry weight (DW), 41.7 mg CEg-1 DW, and 88.6% antioxidant activity, respectively. Vacuum drying resulted in moderate levels of bioactive compounds, while hot air drying yielded the lowest values. Volatile compound analysis, based on relative peak areas obtained from Gas Chromatography-Mass Spectrometry (GC-MS), indicated that freeze drying retained the highest levels of key aroma compounds, including hexanal (15.4%), ethyl acetate (13.9%), methyl acetate (5.7%), benzaldehyde (5.2%), 1-butanol (4.4%), linalool (3.5%), hexane (3.3%), and 2-nonanol (3.1%). The heatmap and ANOVA analyses consistently demonstrated that the drying method had a significant effect on volatile compound retention, with freeze drying identified as the most effective technique for preserving the native aroma profile. One-way ANOVA showed statistically significant differences between groups (P < 0.001). Multivariate analysis via Principal Component Analysis (PCA) revealed clear distinctions in both bioactive profiles and volatile compositions across the drying methods. Overall, freeze drying proved to be the most effective method for preserving both bioactive and volatile components in dried 'Nero' aronia fruits.