Table 4.
Physical propertiesa,b including the Hunter Lab color parameters and antioxidant capacitya−c determined on 57.7% equilibrated low methoxyl pectin films made without (0%) or with increasing concentrations of 53-μm sunflower seed hull powder (SP).
| Composite films (SP % w/w) | SP equilibrated at 57.7% RH | ||||
|---|---|---|---|---|---|
| 0 | 5 | 8 | 12 | ||
| Thickness (mm) | 0.113 ± 0.004A | 0.121 ± 0.006AB | 0.128 ± 0.011BC | 0.139 ± 0.006C | – |
| L (%) | 81 ± 5A | 73 ± 2B | 68 ± 2C | 65 ± 1D | – |
| a | −1.3 ± 0.7A | +0.16 ± 0.19B | +0.89 ± 0.27C | +1.42 ± 0.18D | – |
| b | +14.6 ± 0.8A | +15.9 ± 0.3B | +16.2 ± 0.3BC | +16.2 ± 0.2C | – |
| Water content (g/100 g dm) | 46.5 ± 0.2A | 44.1 ± 0.3B | 43.3 ± 0.2B | 42.0 ± 0.2C | – |
| Glass transition temperature, Tg (°C) | −80.74 | −94.64 27.81 |
−99.83 −78.90 26.59 |
−99.70 −79.74 67.39 |
−87.96 14.23 59.39 |
| Change in specific heat at the glass transition [J.g−1 (dm).K−1] | 1.359 | 1.233 2.777 |
0.788 1.326 2.363 |
0.843 1.401 2.574 |
2.381 0.075 0.05119 |
| Contact angle (°) measured at 5 s | 22 ± 3AB | 29 ± 9A, C | 24 ± 4A, C | 26 ± 3CB | – |
| Contact angle (°) measured at 60 s | 16 ± 4A | 24 ± 9A | 17 ± 4A | 22 ± 3A | – |
| WVP × 1010 (g·m−1·s−1·Pa−1) (25°C; 0%/70% RH) | 13.7 ± 0.1A | 9.2 ± 0.3B | 9.8 ± 0.1B | 9.7 ± 0.1B | – |
| DPPH3 (mg AA/100 g film) | NDA | 12.9 ± 0.6B | 27 ± 6C | 32 ± 2AB | – |
| FRAP3 (mg AA/100 g film) | 23 ± 3A | 35 ± 4B | 38 ± 1BC | 42.6 ± 0.2C | – |
The glass transition results obtained from SP are also summarized.
a
Mean and standard deviations for n = 3 (n ≥ 12 for color parameters) are reported.
b
The same capital letter as superscript of data in a given row means non-significant differences (p < 0.05).
c
Results of the DPPH and FRAP assays are expressed as L-(+)-ascorbic acid (AA), which was used as standard.
Dm, dry mass; ND, non-detectable; RH, relative humidity (Equation 1).