Objective To study the effects of two kinds of processing techniques, ultrafine grinding and spray drying, on the metabolites of apple powder. Methods Liquid chromatography-tandem mass spectrometry was used to compare the effects of ultrafine grinding and spray drying technologies on the types of metabolites, expression abundance, correlation analysis, and kyoto encyclopedia of genes and genomes (KEGG) pathways of apple powder. Results The results indicated that compared with ultrafine grinding, spray-dried apple powder had reduced particle size D[50] 3.91 μm, D[3,2] 2.62 μm, D[4,3] 5.52 μm, increased specific surface area (850.10 m2/kg), and decreased span value (2.51). Principal component analysis showed that the cumulative variance contribution rate of apple powder under these two processing technologies was 82.7%, suggesting that the processing methods had a significant influence on the metabolite composition. A total of 244 metabolites were identified, including lipids, phenylpropanoids, and benzenoids. Abundance expression showed that ultrafine grinding outperformed spray drying in retaining natural nutritional components. The sample correlation analysis and heatmaps indicated that metabolite expression in spray-dried apple powder had higher uniformity and stability. Univariate statistical analysis revealed that, compared with ultrafine grinding, spray-dried apple powder had 1172 kinds of substances upregulated and 2550 kinds of substances downregulated. Differential metabolite correlation analysis showed that different processing techniques were positively correlated with specific metabolites in apple powder, such as ginsenoside F1 and N-fructosyl pyroglutamate, and negatively correlated with salicylic acid and aspartic acid, among others. KEGG pathway enrichment analysis highlighted the most active pathway as the biosynthesis of unsaturated fatty acids. Conclusion It has been demonstrated that ultrafine grinding is suitable for the production of healthy and special nutritional food products, while spray drying is more appropriate for quick-service foods and the baking industry, laying a theoretical foundation for ensuring food safety and quality control.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |