Table 5.
Quantification and bioaccessibility percentage of the phenolic compounds of SPD and MEC.
| Phenolic compounds | SPD | MEC | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Non-digested | Gastric | Bioaccessibility | Intestinal | Bioaccessibility | Non–digested | Gastric | Bioaccessibility | Intestinal | Bioaccessibility | |
| phase | (%) 9 | phase | (%) | phase | (%) | phase | (%) | |||
| TSPC 1 | 0.93 ± 0.02b | 0.86 ± 0.02a | 93.03 | 0.84 ± 0.02a | 90.47 | 0.60 ± 0.01b* | 0.50 ± 0.01a* | 84.10 | 0.72 ± 0.01c* | 120.14 |
| 2,4-dihydroxybenzoic acid (i1)2 | tr | tr | – | tr | – | tr | tr | – | tr | – |
| 2,4-dihydroxybenzoic acid (i2)2 | tr | tr | – | tr | – | tr | tr | – | tr | – |
| 2,4-dihydroxybenzoic acid (i3)2 | tr | tr | – | tr | – | tr | tr | – | tr | – |
| 4-hydroxybenzoic acid (i1)3 | 4.35 ± 0.18 b | 5.93 ± 0.17 c | 136.52 | 2.24 ± 0.35 a | 51.51 | 4.71 ± 0.07 b | 1.31 ± 0.12 a,* | 27.97 | tr | – |
| 4-hydroxybenzoic acid (i2)3 | tr | tr | – | tr | – | tr | tr | – | tr | – |
| Vanillic acid4 | 4.33 ± 0.07b | 6.27 ± 0.42c | 144.93 | 2.59 ± 0.07a | 59.82 | 5.87 ± 0.14b* | 0.74 ± 0.09a,* | 12.65 | nd | – |
| Total hydroxybenzoic acids | 8.68 ± 0.12b | 12.21 ± 0.60c | 140.62 | 4.83 ± 0.41a | 55.68 | 10.57 ± 0.21b* | 2.06 ± 0.21a* | 19.47 | tr | – |
| Caffeic acid5 | tr | tr | – | tr | – | tr | tr | – | tr | – |
| Trans-ferulic acid6 | 175.22 ± 3.26a | 227.06 ± 9.13b | 129.66 | 178.10 ± 1.60a | 101.68 | 102.70 ± 2.79c* | 91.15 ± 4.63b* | 88.81 | 78.17 ± 5.90a* | 76.64 |
| Cis-ferulic acid6 | 3.09 ± 0.08a | 4.96 ± 0.34b | 160.81 | 5.09 ± 0.33b | 164.94 | 2.28 ± 0.30b | 1.61 ± 0.12a* | 70.91 | 1.63 ± 0.01a* | 72.09 |
| Total hydroxycinnamic acids | 178.31 ± 0.08a | 232.02 ± 0.34c | 130.12 | 183.19 ± 0.33b | 102.74 | 104.98 ± 0.30c* | 92.76 ± 0.12b* | 88.36 | 79.80 ± 0.01a* | 76.01 |
| Apigenin-6-C-arabinoside-8-C-hexoside(i1)7 | tr | tr | – | tr | – | tr | nd | – | nd | – |
| Apigenin-6-C-arabinoside-8-C-hexoside(i2)7 | 3.12 ± 0.18a | 4.02 ± 0.06b | 129.23 | 3.06 ± 0.07a | 98.32 | 2.05 ± 0.01* | tr | – | tr | – |
| Apigenin-6-C-arabinoside-8-C-hexoside(i3)7 | 7.12 ± 0.58a | 9.15 ± 0.02b | 128.88 | 8.19 ± 0.37ab | 115.13 | 4.81 ± 0.05c* | 0.31 ± 0.11a* | 6.40 | 1.01 ± 0.07b* | 21.09 |
| Apigenin-6-C-arabinoside-8-C-hexoside(i4)7 | tr | tr | - | tr | – | tr | tr | – | tr | – |
| Total flavones | 10.24 ± 0.75a | 13.17 ± 0.07b | 128.97 | 11.25 ± 0.45a | 110.01 | 6.86 ± 0.04c* | 0.31 ± 0.11a* | 4.49 | 1.01 ± 0.07b* | 14.79 |
| Vanillin8 | 0.08 ± 0.01a | 0.44 ± 0.01c | 583.65 | 0.33 ± 0.06b | 424.35 | 0.26 ± 0.02* | tr | – | tr | – |
| Total hydroxybenzaldehydes | 0.08 ± 0.01a | 0.44 ± 0.01c | 583.65 | 0.33 ± 0.06b | 424.35 | 0.26 ± 0.02* | tr | – | tr | – |
Data are mean values ± standard deviation of three replicates. Different lowercase letters in the same row indicate significant differences between means in different digestion phases (one-way ANOVA, post-hoc Duncan's test, p ≤ 0.05).
denotes significant differences among wheat derived ingredients in the same phases of digestion (one-way ANOVA, post-hoc Duncan's test, p ≤ 0.05). SPD, hydrolyzed WB spray-dried at 130°C; MEC, hydrolyzed WB spray-dried at 130°C and microencapsulated with Pisane C9; i, isomer; nd, non-detected; TSPC, total soluble phenolic compounds; tr, traces. 1g/100 g gallic acid equivalents. 2mg/100 g 2,4-dihydroxybenzoic acid (linearity range 0–3.75 μg/mL, R2 = 1). 3mg/100 g 4-hydroxybenzoic acid (linearity range 0–3.75 μg/mL, R2 > 0.99). 4mg/100 g vanillic acid (linearity range 0.47–3.75 μg/mL, R2 > 0.98). 5mg/100 g caffeic acid (linearity range 0–2.77 μg mL, R2 > 0.99, LOD = 0.16 μg mL, LOQ = 0.47 μg/mL). 6mg/100 g ferulic acid (linearity range 0–25 μg/mL, R2 = 1, LOD = 0.04 μg/mL, LOQ = 0.12 μg/mL). 7mg/100 g vicenin-2 (linearity range 0–25 μg/mL, R2 = 1, R2 = 1, LOD = 0.02 μg/mL, LOQ = 0.05 μg/mL). 8mg/100 g vanillin (linearity range 0–3.75 μg/mL, R2 = 1). 9Bioaccessibility expressed as percentage was calculated as the ratio of free phenolic compounds released from food matrix during digestion and the initial content of free phenolic compounds in the wheat ingredients before digestion (values over 100% are indicative of increase in the bioaccessible amount of phenolic compounds in each digestion phase).