Ultrasound-enhanced bio-based active packaging films derived from passion fruit waste pectin: structural evolution, property correlations, and antioxidant activity through eggshell and oleuropein integration
Bibliographic record
Abstract
Passion fruit peel, rich in natural pectin, is often discarded as agricultural waste, resulting in a significant loss of its potential value. In this study, pectin was extracted from discarded passion fruit peels and used to fabricate a multifunctional composite film Via an ultrasound-assisted casting method, incorporating eggshell powder and oleuropein as functional additives. Ultrasound treatment not only promoted the uniform dispersion of fillers, but also facilitated molecular interactions, thereby enhancing film formation and structural integrity. The molecular structure, mechanical strength, thermal stability, barrier properties, and antioxidant activity of the resulting films were systematically investigated. Through optimization experiments, the best-performing film was found to contain 2 % (w/w) eggshell powder and 1 % (w/w) oleuropein. This formulation provided the highest overall performance, achieving a tensile strength of 2.68 MPa, a water vapor transmission rate of 11.66 g/m 2 /24 h, and a DPPH radical scavenging activity of 80 %. (1) FTIR analysis revealed that Ca 2+ ions from eggshell powder formed stable ionic cross-linking networks with pectin molecules, as evidenced by the redshift of hydroxyl stretching peaks (from 3300 to 3259 cm −1 ), indicating the formation of coordination bonds. (2) When the concentration of eggshell powder ranged from 1.5 to 2.5 %, the tensile strength of the film increases of 1.77–2.68 MPa, while the water vapor transmission rate decreased of 14.31–11.66 g/m 2 /24 h, representing an 18.4 % enhancement in barrier performance. (3) The incorporation of oleuropein significantly improved the antioxidant capacity of the film in a dose-dependent manner. Specifically, 2,2-diphenyl-1-picrylhydrazyl (DPPH)radical cavenging activity increased markedly from 16 % to 80 % as the oleuropein concentration was elevated from 0.1 to 1.5 %. This progressive enhancement reflects the strong electron-donating and hydrogen-atom transfer ability of oleuropein, which can effectively neutralize free radicals and terminate chain reactions of oxidative processes. The polyphenolic structure of oleuropein provides multiple hydroxyl groups capable of interacting with reactive species, thereby amplifying the overall antioxidant response of the composite films. These findings demonstrate that the developed composite film holds great promise for active food packaging applications, providing a sustainable approach for the high-value utilization of agricultural by-products and promoting the development of eco-friendly packaging materials.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".