Enhanced microstructural and metabolic transformations of Gardenia jasminoides ellis via high-humidity hot air impingement blanching: Implications for improved drying rate and product quality

As a plant with both medicinal and edible properties, Gardenia jasminoides Ellis ( GJE ) holds significant commercial value in the health supplement market. However, the "dual barriers" formed by waxy layers and internal protective membranes lead to a low drying rate, presenting critical challenges for postharvest processing of GJE . To address this, this study employed a novel pretreatment technology, high-humidity hot air impingement blanching (HHAIB), for GJE . The mechanism of how HHAIB affects the drying characteristics and physicochemical quality was investigated from multiple perspectives. Results demonstrated that HHAIB-treated samples exhibited softened texture and porous microstructures compared to unblanched and hot water-blanched samples. This structural reorganization altered water distribution patterns and hydrogen bonding interactions, facilitating conversion between immobilized and free water, thereby reducing drying time by 16.58 % ( p < 0.05). Concurrently, HHAIB for 90 s significantly increased geniposide, crocin I, and chlorogenic acid content by 18.17 %, 20.55 %, and 280 %, respectively ( p < 0.05), exhibiting a redder and brighter color, which is more likely to gain consumer preference. UPLC-MS/MS coupled with metabolomics revealed significant metabolic profile differences between HHAIB-treated and unblanched samples ( p < 0.05), with differential metabolite counts increasing with prolonged blanching. Crucially, significant enrichment in phenylpropanoid biosynthesis ( p < 0.0003) was observed at 90 s—a critical route for synthesizing chlorogenic acid and other bioactive compounds. Overall, HHAIB remodulates microstructure, enhances bioactive retention, and accelerates drying, offering an eco-friendly, high-quality processing method for GJE . • HHAIB reduced the drying time by 16.58 % than unblanched GJE . • HHAIB exhibited better bioactive compounds and color retention than HWB. • HHAIB improved drying rate by altering the microstructure and moisture state. • HHAIB enhanced chemical quality by activating metabolic pathway synthesis. • HHAIB-90 s was optimum according to efficiency and quality of GJE .