Primary surface measurement reported
The paper reports water contact angle on the optimized alfalfa lignocellulosic extract film as part of its hydration-property characterization.
Client Citation Analysis
Green Valorization of Alfalfa into Sustainable Lignocellulosic Films for Packaging Applications
This study develops and optimizes alfalfa-derived lignocellulosic packaging films, with water contact angle measured by a Dropometer to characterize hydration behavior and film surface wettability.
At-a-Glance Summary
Dropometer attribution in the paper
The authors state that water contact angle was determined using “a Dropometer (Droplet Lab, Markham, ON, Canada)” by placing a water droplet on the film surface and recording the angle immediately.
How the surface-tension / contact-angle data were used in the study
The contact-angle data were used to describe the film’s hydrophobicity and time-dependent wetting behavior within the hydration-properties section. The authors interpreted these results together with moisture content, water solubility, and water absorption to discuss packaging suitability for moisture-insensitive foods such as fresh fruits and vegetables.
Paper Details
Title
Green Valorization of Alfalfa into Sustainable Lignocellulosic Films for Packaging Applications
Authors
Sandeep Paudel; Srinivas Janaswamy
Journal
Applied Sciences
Year
2025
Volume
15
Pages / Article
11889
License
Creative Commons Attribution (CC BY) license
Journal context
What it is
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Scopus metrics (Elsevier / Scopus rating)
CiteScore
5.5
CiteScore subject ranks
- Q1 - General Engineering
Journal Impact Factor (Clarivate JCR)
Journal Impact Factor (JCR 2024)
2.5
5-Year Impact Factor
2.7
JCR category rank
Q1 - Engineering, Multidisciplinary (44/179)
What Was Measured
Primary surface / interfacial measurement
The primary surface measurement reported with the Dropometer is water contact angle on the optimized ALE film. The paper reports 78.9 ± 2.3° at 0 s, decreasing to 69.9 ± 0.5° at 10 s, 60.9 ± 1.5° at 20 s, and 54.5 ± 0.4° at 30 s.
Supporting measurements
The study also reports tensile strength, elongation at break, water vapor permeability, color, transparency, UV–Vis–IR transmittance, absorbance coefficient, FTIR spectra, antioxidant activity, moisture content, water solubility, water absorption with kinetic-model fitting, and soil biodegradation. These measurements were used to build the overall packaging-performance profile of the optimized film.
Role of the Dropometer
The Dropometer was used for sessile-drop water contact angle measurement on the optimized alfalfa lignocellulosic extract film. In the methods section, the authors describe placing a water droplet on the film surface and recording the angle immediately; in the hydration-results section, the resulting contact-angle profile is presented at 0, 10, 20, and 30 s.
In this study, the Dropometer output was part of the hydration-property package the authors used to interpret how the optimized film wets over time and how that surface behavior aligns with packaging use for moisture-insensitive foods.
Key Findings
Optimized formulation
The study optimized the film formulation at 0.5 g ALE, 453.8 mM CaCl2, and 1.5% sorbitol. That optimized film delivered 11.2 ± 0.7 MPa tensile strength, 5.8 ± 0.9% elongation at break, and 1.2 ± 0.2 × 10−10 g m−1 s−1 Pa−1 water vapor permeability.
Moderate initial hydrophobicity
The optimized ALE film showed a water contact angle of 78.9 ± 2.3° at 0 s. The authors discuss this as part of the film’s hydrophobicity profile within the hydration-properties section.
Time-dependent wetting
The contact angle declined steadily over 30 s, from 78.9° to 54.5°. The authors attribute this decrease to the inherent absorption, spreading, and swelling behavior of biopolymers.
Hydration profile tied to lignin-containing films
The paper links the film’s hydration behavior to the retained lignin fraction, stating that lignin hinders water penetration and increases hydrophobicity. In the same hydration section, water absorption rose from 45.3 ± 1.5% at 5 min to 69.3 ± 1.0% at 120 min, with the Peleg model giving the best kinetic fit (R² = 0.9990; RMSE = 0.0179).
Packaging functionality beyond wetting
The optimized film combined hydration behavior with UV–Vis–IR light blocking, antioxidant activity, and rapid soil biodegradation, reaching over 90% biodegradation within 29 days at 24% soil moisture. The authors position this overall profile for sustainable packaging applications.
Figures & Visuals
Figure 3a — Contact-angle decay over 30 seconds
What it shows
This panel shows the optimized ALE film’s water contact angle decreasing from 78.9 ± 2.3° at 0 s to 54.5 ± 0.4° at 30 s.
Figure 3b — Water-absorption context for the wettability result
What it shows
This panel shows water absorption increasing over time to 69.3 ± 1.0% at 120 min, providing hydration context alongside the Dropometer-derived wetting data.
Figure 3c — End-of-life context for the packaging film
What it shows
This panel shows soil biodegradation progressing beyond 90% by day 29, connecting the film’s surface and hydration behavior to its biodegradable packaging use case.
Why It Matters
In this paper, the Dropometer data give a direct readout of how the optimized alfalfa film surface interacts with water over time. That matters because the study frames hydration behavior as part of packaging suitability, and the contact-angle results sit alongside moisture content, water solubility, and water absorption in the authors’ interpretation of film performance.
The broader value in the paper is application fit: the authors combine the contact-angle profile with barrier, optical, antioxidant, and biodegradation data to support alfalfa-derived lignocellulosic films as a sustainable packaging material, particularly for moisture-insensitive products and for foods that benefit from light protection.
Practical Takeaways
Wetting starts near 79°
The optimized ALE film begins with a water contact angle of 78.9 ± 2.3°, giving a clear baseline for how the surface initially presents to water.
Wetting changes quickly over 30 s
The measured decline to 54.5 ± 0.4° by 30 s shows that this is a dynamic wetting system rather than a static single-point surface result.
Surface data were interpreted with hydration metrics
The contact-angle output was most informative in combination with moisture content, solubility, and water-absorption behavior, rather than as a stand-alone number.
The result is tied to one optimized formulation
The reported Dropometer values belong to the optimized film made with 0.5 g ALE, 453.8 mM CaCl2, and 1.5% sorbitol, which is the formulation the paper carries forward into detailed characterization.
Packaging interpretation is application-specific
The authors use the surface and hydration results to support packaging for moisture-insensitive foods, while the film’s light-blocking and antioxidant properties broaden its relevance to light-sensitive and oxidation-sensitive products.