Development of Bio-Composites with Enhanced Antioxidant Activity Based on Poly(lactic acid) with Thymol, Carvacrol, Limonene, or Cinnamaldehyde for Active Food Packaging
Abstract
:1. Introduction
2. Materials and Methods
2.1. Materials
2.2. Experimental Procedure
2.3. Quantification of the Active Ingredients in the PLA Matrix
2.4. Analytical Techniques
2.5. Mathematical Modeling of the Release Rate Profiles
3. Results
3.1. Quantification of the Active Ingredinets in the PLA Matrix and Characterization of the Chemical Structure of the Composites Prepared
3.2. Thermal Properties
3.3. Release Profiles of the Active Compounds from the Polymer Matrix and Study of the Process Kinetics
- Samples are considered isotropic of similar shape and with equal initial active compound concentration.
- The effective diffusion coefficient through the samples is constant.
- There is no resistance to the mass transfer of the active compound from the external surfaces of the samples.
- The active compound is uniformly distributed in the samples.
3.4. Antioxidant Properties
4. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Experiment # | Code | Thymol (wt%) | Carvacrol (wt%) | Limonene (wt%) | Cinnamaldehyde (wt%) |
---|---|---|---|---|---|
1 | PLA | 0 | 0 | 0 | 0 |
2 | PLA-5Th | 5 | 0 | 0 | 0 |
3 | PLA-10Th | 10 | 0 | 0 | 0 |
4 | PLA-5Ca | 0 | 5 | 0 | 0 |
5 | PLA-10Ca | 0 | 10 | 0 | 0 |
6 | PLA-5Lim | 0 | 0 | 5 | 0 |
7 | PLA-10Lim | 0 | 0 | 10 | 0 |
8 | PLA-5Ci | 0 | 0 | 0 | 5 |
9 | PLA-10Ci | 0 | 0 | 0 | 10 |
10 | PLA-ThCaLim | 3.33 | 3.33 | 3.33 | 0 |
11 | PLA-ThCaCi | 3.33 | 3.33 | 0 | 3.33 |
12 | PLA-ThLimCi | 3.33 | 0 | 3.33 | 3.33 |
13 | PLA-CaLimCi | 0 | 3.33 | 3.33 | 3.33 |
14 | PLA-ThCaLimCi | 2.5 | 2.5 | 2.5 | 2.5 |
Code | Preparation Method | Initial Loading of the Active Ingredient (wt%) | Loading Capacity (wt%) | Encapsulation Efficiency (%) |
---|---|---|---|---|
PLA | 0 | n.d. | 0 | |
PLA-5Th | Melt mixing | 5 | 3.6 ± 0.1 | 72 ± 3 |
PLA-10Th | Melt mixing | 10 | 6.8 ± 0.2 | 68 ± 2 |
PLA-5Th | Solution casting | 5 | 4.9 ± 0.1 | 98 ± 2 |
PLA-10Th | Solution casting | 10 | 9.5 ± 0.2 | 95 ± 2 |
PLA-5Ca | Solution casting | 5 | 4.8 ± 0.1 | 97 ± 3 |
PLA-10Ca | Solution casting | 10 | 9.6 ± 0.2 | 96 ± 2 |
PLA-5Lim | Solution casting | 5 | 4.6 ± 0.1 | 92 ± 2 |
PLA-10Lim | Solution casting | 10 | 9.0 ± 0.3 | 90 ± 3 |
PLA-5Ci | Solution casting | 5 | 4.7 ± 0.2 | 94 ± 4 |
PLA-10Ci | Solution casting | 10 | 9.7 ± 0.1 | 97 ± 1 |
Material | Tg (°C) | ΔCp (J/g·°C) | Tm1 (°C) | Tm2 (°C) | Tcc (°C) | ΔHcc (J/g) | ΔHf (J/g) | Xc (%) |
---|---|---|---|---|---|---|---|---|
PLA | 58.4 | 0.43 | 147.4 | 155.1 | 107.7 | 26.34 | 27.53 | 29.6 |
PLA-10 Th | 56.6 | 0.30 | 146.8 | 154.4 | 109.1 | 23.93 | 25.16 | 29.7 |
PLA-10 Ca | 55.1 | 0.43 | 148.1 | 154.5 | 111.4 | 24.34 | 25.28 | 30.0 |
PLA-10 Lim | 54.8 | 0.33 | 147.5 | 153.7 | 111.3 | 23.74 | 24.94 | 29.5 |
PLA-10 Ci | 50.0 | 140.4 | 150.1 | 103.0 | 23.72 | 24.68 | 29.2 | |
PLA-ThCaLim | 56.2 | 0.24 | 146.5 | 154.2 | 107.5 | |||
PLA-ThCaCi | 52.3 | 0.34 | 146.7 | 152.0 | 104.9 | |||
PLA-ThLimCi | 49.5 | 0.58 | 147.5 | -- | 111.3 | |||
PLA-CaLimCi | 54.2 | 0.54 | 147.0 | 152.8 | 109.0 | |||
PLA-ThCaLimCi | 49.4 | 0.34 | 145.6 | -- | 107.4 |
Thymol | Carvacrol | |||||||
---|---|---|---|---|---|---|---|---|
Temperature (°C) | Df (10−6 cm2/s) | Ds (cm2/s) | f | R2 | Df (10−6 cm2/s) | Ds (cm2/s) | f | R2 |
50 | 0.04 | 10−13 | 0.72 | 0.997 | 0.04 | 10−13 | 0.60 | 0.988 |
100 | 0.4 | 10−10 | 0.72 | 0.948 | 0.4 | 10−10 | 0.60 | 0.968 |
122 | 0.9 | 10−9 | 0.72 | 0.939 | 1.2 | 10−9 | 0.60 | 0.962 |
142 * | 1.8 | 10−8 | 0.73 | 0.991 | 2.3 | 3 × 10−8 | 0.68 | 0.986 |
165 | 5.0 | 1.8 × 10−7 | 0.72 | 0.992 | 4.0 | 2 × 10−7 | 0.72 | 0.989 |
Ln (D0(cm2/s)) | Ea (kJ/mol) | R2 | |
---|---|---|---|
Carvacrol | |||
Fast | 0.805 ± 0.162 | 47.9 ± 1.5 | 0.9962 |
Slow | 25.20 ± 2.03 | 148.8 ± 6.5 | 0.9925 |
Thymol | |||
Fast | 0.866 ± 0.582 | 48.2 ± 1.8 | 0.9941 |
Slow | 23.63 ± 1.67 | 144.4 ± 5.3 | 0.9946 |
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Siddiqui, M.N.; Redhwi, H.H.; Tsagkalias, I.; Vouvoudi, E.C.; Achilias, D.S. Development of Bio-Composites with Enhanced Antioxidant Activity Based on Poly(lactic acid) with Thymol, Carvacrol, Limonene, or Cinnamaldehyde for Active Food Packaging. Polymers 2021, 13, 3652. https://doi.org/10.3390/polym13213652
Siddiqui MN, Redhwi HH, Tsagkalias I, Vouvoudi EC, Achilias DS. Development of Bio-Composites with Enhanced Antioxidant Activity Based on Poly(lactic acid) with Thymol, Carvacrol, Limonene, or Cinnamaldehyde for Active Food Packaging. Polymers. 2021; 13(21):3652. https://doi.org/10.3390/polym13213652
Chicago/Turabian StyleSiddiqui, Mohammad Nahid, Halim Hamid Redhwi, Ioannis Tsagkalias, Evangelia C. Vouvoudi, and Dimitris S. Achilias. 2021. "Development of Bio-Composites with Enhanced Antioxidant Activity Based on Poly(lactic acid) with Thymol, Carvacrol, Limonene, or Cinnamaldehyde for Active Food Packaging" Polymers 13, no. 21: 3652. https://doi.org/10.3390/polym13213652
APA StyleSiddiqui, M. N., Redhwi, H. H., Tsagkalias, I., Vouvoudi, E. C., & Achilias, D. S. (2021). Development of Bio-Composites with Enhanced Antioxidant Activity Based on Poly(lactic acid) with Thymol, Carvacrol, Limonene, or Cinnamaldehyde for Active Food Packaging. Polymers, 13(21), 3652. https://doi.org/10.3390/polym13213652