Primary surface measurement reported
Water contact angle (WCA) was measured on the ACR control film and nine ACR-carrageenan composite films, with reported values ranging from 74.7 ± 0.4° for ACR to 60.9 ± 0.1° for ACR-l1.5%.
Client Citation Analysis
Biodegradable films based on alfalfa cellulosic residue and carrageenan blends for sustainable food packaging
This study developed biodegradable alfalfa cellulosic residue–carrageenan films and used dropometer-based water contact angle measurements to compare how carrageenan type and loading changed film hydrophilicity within a broader packaging-property evaluation.
At-a-Glance Summary
Dropometer attribution in the paper
The methods state: “The water contact angle was measured using a dropometer by placing a water droplet and recording the resulting angle.”
How the surface-tension / contact-angle data were used in the study
The contact-angle data were used to compare how iota-, kappa-, and lambda-carrageenan changed film hydrophilicity across concentration series and to interpret the films’ water absorption behavior in the packaging study.
Paper Details
Title
Biodegradable films based on alfalfa cellulosic residue and carrageenan blends for sustainable food packaging
Authors
Sandeep Paudel and Srinivas Janaswamy
Journal
Sustainable Food Technology
Year
2026
Volume
4
Pages / Article
1633–1647
DOI
https://doi.org/10.1039/d5fb00872g
License
Creative Commons Attribution 3.0 Unported Licence
Journal context
What it is
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How to read it
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Scopus metrics (Elsevier / Scopus rating 2024)
CiteScore 2024
3.6
CiteScore subject ranks (CiteScore 2024)
- Q2 - Food Science (180/404).
- Q3 - Analytical Chemistry (89/160).
SNIP 2024
1.208
SJR 2024
0.839
Journal Impact Factor (Clarivate JCR)
Journal Impact Factor (JCR 2024)
5.3
JCR category rank
Q1 - Food Science & Technology
What Was Measured
Primary surface / interfacial measurement
The paper reports water contact angle (WCA) for the ACR control and the ACR-i, ACR-k, and ACR-l films at 0.5%, 1.0%, and 1.5% carrageenan levels. Reported WCA values decrease across the film set from 74.7 ± 0.4° for ACR to 60.9 ± 0.1° for ACR-l1.5%.
Supporting measurements
The same film matrix was also characterized for tensile strength, elongation at break, water vapor permeability, moisture content, water solubility, water absorption and kinetics, color, UV-Vis-IR transmittance, FTIR, antioxidant activity, and soil biodegradation. These measurements were used alongside WCA to interpret the films’ mechanical performance, moisture interaction, light-blocking behavior, and biodegradation behavior.
Role of the Dropometer
The dropometer was used during film characterization to place a water droplet on each film and record the resulting contact angle. The reported output is WCA in degrees for the ACR control and each ACR-carrageenan formulation, with the values compiled in Table 2.
Within the paper’s workflow, these measurements provided the wettability comparison across carrageenan type and concentration that the authors used to discuss hydrophilicity and its relationship to water absorption.
Key Findings
Carrageenan lowered the contact angle across the film set
WCA decreased from 74.7 ± 0.4° for the ACR control to values between 70.5 ± 0.4° and 60.9 ± 0.1° in the composite films. The authors interpret this shift as increased hydrophilicity after carrageenan addition.
Lambda-carrageenan produced the lowest reported WCA
Among the reported formulations, ACR-l1.5% showed the lowest WCA at 60.9 ± 0.1°. Within the lambda series, WCA decreased from 70.5 ± 0.4° at 0.5% to 65.0 ± 1.2° at 1.0% and 60.9 ± 0.1° at 1.5%.
Wettability tracked with stronger water uptake
The more hydrophilic films also showed higher water absorption at 120 minutes. The ACR control reached 152.0 ± 0.2%, while ACR-l1.5% reached 173.9 ± 0.9%, which the paper discusses alongside the hydrophilic character introduced by carrageenan.
The same formulations combined lower WCA with higher strength
Across the same ACR-carrageenan matrix, tensile strength increased from 16.9 ± 0.4 MPa for ACR to 29.9 ± 1.5 MPa for ACR-l1.5%, while WCA moved downward across the composite set. In the paper’s overall interpretation, carrageenan reinforced the films while also making them more hydrophilic.
Contact-angle results sat within a broader packaging-property screen
The WCA data were interpreted together with water solubility, water absorption kinetics, WVP, UV-Vis-IR transmittance, antioxidant activity, and biodegradation. That made wettability one of the property axes used to compare the ten film formulations for sustainable food-packaging use.
Figures & Visuals
Figure 1 — Workflow context for the contact-angle study
What it shows
On page 3, the experimental overview shows the ACR/carrageenan film-making workflow and lists water contact angle among the characterization outputs used for the film matrix.
Figure 2 — Shared formulation matrix for property comparison
What it shows
On page 5, Fig. 2 presents tensile strength, elongation at break, and WVP across the same ACR, ACR-i, ACR-k, and ACR-l formulations whose WCA values are reported in Table 2.
Figure 3 — Wettability-linked water uptake behavior
What it shows
On page 7, Fig. 3 shows water-absorption curves for the control and carrageenan-containing films, providing the moisture-interaction context discussed alongside the WCA results.
Figure 4 — Optical behavior of the high-carrageenan films
What it shows
On page 8, Fig. 4 shows UV-Vis-IR transmittance and absorption-coefficient data for the higher-carrageenan films, complementing the same formulation comparisons used in the contact-angle analysis.