# More pectin increased tensile strength in experimental cactus films

> A study of freeze-dried cactus powder and pectin found higher tensile strength in selected blends, while the pectin-only control remained stronger. The films were hydrophilic, and the authors call for food-storage trials and quantitative degradation tests.

URL: https://foodradar.org/opuntia-and-pectin-films-show-improved-strength-but-remain-water-sensitive-in-lab-tests
Language: en
Author: FoodRadar Editorial
Published: 2026-10-15T20:50:05.019775+00:00
Updated: 2026-10-22T23:42:13.644Z
Source publication date: 2026-09-23
Category: Packaging
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## Four cactus blends were compared with a pectin control

Increasing the amount of pectin raised tensile strength in experimental films made with whole Opuntia ficus-indica cactus pads, a study in Plant Foods for Human Nutrition reports. The blends remained weaker in tension than the pectin-only control. The researchers blended and freeze-dried the pads to obtain a powder, using the whole material rather than extracting its mucilage separately.

The four blends each contained 2 g of cactus powder and 0.5, 1.0, 1.5 or 2.0 g of pectin, designated F1 to F4. Glycerol was used as a plasticizer at 30% by weight of total solids. The control contained 2 g of pectin and glycerol without cactus powder. Preliminary cactus–glycerol formulations without pectin were too brittle for further characterization.

## Strength and elongation differed between formulations

Tensile strength increased from 2.62 MPa in F1 to 8.69 MPa in F3, with no significant difference between F3 and F4. The pectin-only control reached 15.23 MPa, significantly above every blend. The control had the lowest elongation at break, 1.86%, compared with 10.30% for F1 and 12.46% for F2. The supplementary methods specify three replicate mechanical tests per formulation, with formulation differences assessed by analysis of variance and Tukey’s test at p \< 0.05.

Film thickness increased from 0.137 mm in F1 to 0.177 mm in F4 as the formulations’ solids content rose. The authors note that thickness was not independently controlled and may have contributed to differences in mechanical and water-vapour properties. They also identify the absence of a full proximate composition analysis of the cactus powder and pectin as a study limitation.

## All films had hydrophilic surfaces

Water-contact angles across the five formulations ranged from 30.29° to 39.39°, below the 90° threshold used to describe a hydrophobic surface. Moisture content ranged from 25.11% to 35.98%. The authors relate the films’ sensitivity to water to the hydrophilic character of their components and suggest low-moisture foods as a possible application. They call for studies with real food models and different storage conditions to establish suitability.

Adding cactus powder made the films darker and more opaque than the control. Opacity did not differ significantly between the four cactus blends. The authors suggest that greater opacity could help protect light-sensitive foods, while limiting applications that require transparency.

## Soil and seawater tests monitored disintegration

In the soil test, 2 × 2 cm samples were buried 5 cm deep in mesh baskets and retrieved for photography every two days. Adhering soil prevented reliable mass-loss measurements, so the assessment was qualitative. The authors report extensive disintegration of F1 and F2 by day 12 and residues no longer visually distinguishable from the surrounding soil for all formulations by day 28.

For the seawater test, 1 × 1 cm samples were placed in 50 mL of collected seawater and continuously agitated at 150 rpm. The methods describe agitation until complete solubilization, and the main text reports complete disintegration within two hours and 55 minutes. The authors say standardized quantitative tests, including controlled mass-loss measurements, carbon-dioxide evolution or ASTM/ISO biodegradation assays, are needed to determine degradation kinetics.

## Sources and rights

- [Characterization of Films Based on Opuntia ficus-indica and Pectin](https://doi.org/10.1007/s11130-026-01570-5?utm_source=foodradar.org&utm_medium=referral&utm_campaign=editorial&utm_content=opuntia-and-pectin-films-show-improved-strength-but-remain-water-sensitive-in-lab-tests-en). Plant Foods for Human Nutrition (Dordrecht, Netherlands). Júlia Matos Coqueiro, Júlia Marques Brandão, Stefanny Pereira Atanes, Sibele Santos Fernandes and Deborah Murowaniecki Otero (2026). Characterization of Films Based on Opuntia ficus-indica and Pectin. Plant Foods for Human Nutrition 81,122,published online 23 September 2026. DOI:10.1007/s11130-026-01570-5. © The Author(s) 2026. CC BY 4.0. Editorial adaptation and translation: FoodRadar. [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/?utm_source=foodradar.org&utm_medium=referral&utm_campaign=editorial&utm_content=opuntia-and-pectin-films-show-improved-strength-but-remain-water-sensitive-in-lab-tests-en-license).

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