Table 2.
Total phenolic content in collected ripe date fruit samples that reported in the studies included in this systematic review and meta-analysis (n = 22).
| No. | Studies | Number of cultivars | Storage period/temperature before analysis | Extraction solvents | Moisture |
Total Phenolic Content |
||
|---|---|---|---|---|---|---|---|---|
| mean ± SD (median ± range) % |
mean ± SD (median ± range) mg GAE/100 g FW |
mean ± SD (median ± range) mg GAE/100 g DW |
Min. (cultivar) * Max. (cultivar) Max.:Min. ratio mg GAE/100 g DW |
|||||
| 1 | Mansouri et al., 2005 | 7 | NA*/−18 °C | Methanol (80%) | NA | 4.64 ± 2.15 (3.91 ± 5.87) |
5.8 ± 2.69 (4.89 ± 7.34) |
3.11 (Tazizaout) 10.45 (Tantbouchte) 3.36 |
| 2 | Allaith, 2008 | 7 | 1 day/4 °C | Distilled water | NA | 304.0 ± 44.44 (301.0 ± 126.0) |
380.0 ± 55.55 (376.25 ± 157.5) |
312.5 (Suffry) 470.0 (Mabroom) 1.5 |
| 3 | Abbas et al., 2008 | 8 | NA/4 °C | Methanol (80%) | NA | 10.41 ± 23.81 (1.76 ± 68.36) |
0.93 (Jiroft) 69.29 (Kharak) 74.51 |
|
| 4 | Biglari et al., 2008 | 8 | NA/4 °C | Methanol (80%) | NA | 21.61 ± 48.40 (4.60 ± 138.46) |
2.89 (Jiroft) 141.35 (Kharak) 48.91 |
|
| 5 | Saafi et al., 2009 | 4 | NA/−20 °C | Methanol (50%) | NA | 281.08 ± 111.70 (233.59 ± 238.31) |
351.35 ± 139.63 (291.99 ± 297.88) |
261.78 (Kentichi) 559.66 (Allig) 2.14 |
| 6 | Al-Turki et al., 2010 | 15 | NA/−20 °C | Acetone (80%) | 17.4 ± 3.4 (16.1 ± 10.0) |
352.47 ± 63.37 (335.0 ± 217.0) |
426.05 ± 72.15 (392.27 ± 219.11) |
328.98 (Khalasa (USA)) 548.09 (Gur) 1.67 |
| 7 | Singh et al., 2012 | 3 | NA/−40 °C | Methanol (80%) | NA | 220.0 ± 22.61 (231.0 ± 41.0) |
194.0 (Khasab) 235.0 (Fardh) 1.21 |
|
| 8 | Mrabet et al., 2012 | 11 | 1–2 months/4 °C | Acetone (70%) | NA | 106.28 ± 57.44 (94.48 ± 192.36) |
132.85 ± 71.8 (118.1 ± 240.45) |
36.2 (Rochdi) 276.65 (Deglé Nour) 7.64 |
| 9 | El Arem et al., 2012 | 4 | NA/−20 °C | Methanol (50%) | NA | 240.23 ± 62.42 (230.80 ± 129.5) |
300.28 ± 78.03 (288.5 ± 161.87) |
231.13 (Gasbi) 393.0 (Khalt Dhabi) 1.7 |
| 10 | Benmeddour et al., 2013 | 10 | NA/−40 °C | Acetone (60%) | NA | 493.15 ± 310.85 (309.97 ± 729.02) |
225.57 (Deglet Nour) 954.59 (Ghazi) 4.23 |
|
| 11 | Kchaou et al., 2013** | 6 | NA/−20 °C | Distilled water | 26.4 ± 3.2 (25.8 ± 9.0) |
169.58 ± 42.32 (165.45 ± 122.5) |
230.74 ± 58.17 (236.17 ± 168.86) |
133.17 (Zehdi) 302.03 (Bejo) 2.27 |
| NA/−20 °C | Methanol (88%) | 175.30 ± 62.71 (154.42 ± 178.41) |
238.53 ± 85.99 (208.85 ± 245.25) |
156.35 (Zehdi) 401.6 (Bejo) 2.57 |
||||
| NA/−20 °C | Methanol (50%) | 207.87 ± 57.07 (202.24 ± 146.07) |
281.44 ± 73.34 (273.79 ± 201.44) |
199.44 (Baydh El Hamam) 400.88 (Bejo) 2.01 |
||||
| NA/−20 °C | Acetone (70%) | 317.61 ± 137.12 (302.77 ± 377.05) |
430.22 ± 183.85 (405.43 ± 507.36) |
276.11 (Baydh El Hamam) 783.47 (Bejo) 2.84 |
||||
| NA/−20 °C | Ethanol (100%) | 72.19 ± 14.78 (72.82 ± 39.09) |
98.51 ± 22.36 (97.64 ± 55.3) |
72.21 (Kentichi) 127.51 (Bejo) 1.77 |
||||
| Average | 188.51 ± 58.63 (183.99 ± 170.58) |
255.89 ± 78.66 (246.44 ± 234.82) |
168.28 (Baydh El Hamam) 403.1 (Bejo) 2.4 |
|||||
| 12 | Ghiaba et al., 2014 | 5 | NA/4 °C | Methanol (80%) then Ethyl acetate (50%) | NA | 14.55 ± 5.14 (13.42 ± 13.55) |
9.50 (Tafezauine) 23.05 (Tamjhourt) 2.43 |
|
| 13 | Lemine et al., 2014 | 6 | NA/4 °C | Methanol (80%) | NA | 548.92 ± 99.33 (568.50 ± 255.6) |
405.5 (Tenterguel) 661.1 (Tijib) 1.63 |
|
| 14 | Al-Najada and Mohamed, 2014*** | 2 | 1 day/4 °C | Methanol (80%) | NA | 182.5 ± 38.89 (182.5 ± 55.0) |
228.13 ± 48.61 (228.13 ± 68.75) |
193.75 (Khalas) 262.5 (Shishi) 1.35 |
| 6 months/4 °C | Methanol (80%) | 244.0 ± 62.2 (244.0 ± 88.0) |
305.0 ± 77.78 (305.0 ± 110.0) |
250.0 (Khalas) 360.0 (Shishi) 1.44 |
||||
| 12 months/4 °C | Methanol (80%) | 292.5 ± 17.7 (292.5 ± 25.0) |
365.63 ± 22.1 (365.63 ± 31.25) |
350.0 (Khalas) 381.25 (Shishi) 1.09 |
||||
| Average | 239.67 ± 39.59 (239.67 ± 56.0) |
299.58 ± 49.5 (299.58 ± 70.0) |
264.58 (Khalas) 334.58 (Shishi) 1.26 |
|||||
| 15 | Shahdadi et al., 2015 | 2 | NA/NA | Methanol (80%) | NA | 753.30 ± 41.72 (753.30 ± 59.0) |
723.80 (Jiroft Kalute) 782.80 (Bam Mazfati) 1.08 |
|
| 16 | Hemmateenejad et al., 2015 | 12 | NA/4 °C | Methanol (80%) | NA | 328.89 ± 39.57 (324.54 ± 147.48) |
411.11 ± 49.46 (405.67 ± 184.35) |
313.44 (Khanizi) 497.79 (Karoot) 1.59 |
| 17 | Haimoud et al., 2016 | 7 | NA/4 °C | Methanol (80%) | NA | 4.36 ± 1.45 (4.51 ± 4.47) |
2.06 (Biraya) 6.53 (Ali Ourached) 3.17 |
|
| 18 | Hamza et al., 2016 | 1 | NA/4 °C | Ethanol (80%) | 10.5 | 142.51 | 159.28 |
159.28 (Deglet Nour) |
| 19 | Bouhlali et al., 2017 | 8 | NA/−20 °C | Methanol (80%) | 25.1 ± 5.4 (23.2 ± 14.5) |
466.26 ± 70.78 (494.15 ± 205.21) |
331.86 (Bouskri) 537.07 (Bousrdon) 1.62 |
|
| 20 | Hachani et al., 2018** | 5 | NA/NA | Methanol (80%) | 18.6 ± 9.2 (14.6 ± 22.3) |
36.67 ± 19.80 (32.18 ± 49.47) |
20.38 (Tamazouchete) 69.85 (Takarboucht) 3.43 |
|
| NA/NA | Acetone (70%) | 14.53 ± 2.45 (14.48 ± 6.66) |
11.13 (Tamazouchete) 17.79 (Agaz) 1.60 |
|||||
| Average | 25.6 ± 10.28 (22.93 ± 26.96) |
15.76 (Tamazouchete) 42.72 (Takarboucht) 2.71 |
||||||
| 21 | Haider et al., 2018 | 10 | NA/NA | Methanol (95%) | 21.7 ± 3.6 (22.9 ± 11.7) |
87.0 ± 44.26 (85.22 ± 124.7) |
26.93 (Ko-Herba) 151.63 (Karblian) 5.63 |
|
| 22 | Souli et al., 2018 | 10 | NA/−20 °C | Methanol (100%) | NA | 110.62 ± 8.87 (111.05 ± 25.50) |
138.28 ± 11.09 (138.82 ± 31.88) |
123.25 (Horra) 155.13 (Deglet Nour) 1.26 |
*
Min.: minimum value; Max. maximum value, NA: Data is not available in the study, GAE: Gallic acid equivalents, FW: Fresh weight, DW: Dry weight.
**
Total phenolic content was reported for the same date fruit cultivars that extracted by using more than one solvent.
***
Total phenolic content was reported for the same date fruit cultivars that exposed for three different storage periods.