Table 2.
Effect of, and interactions between, year, production system (organic (ORG) vs. conventional (CON), production region (South Africa (RSA) vs. the Mediterranean (MED)) and table grape type (red vs. white) on the dry matter content (DM), sugar content (SC) of pulp/juice, total phenolic content (TPC), total antioxidant activity (TAA; DPPH and ABTS assays) and total anthocyanin content (TAC) in grape samples from a UK supermarket survey (4-factor ANOVA, the values presented are means ± SE).
| Factors | Dry Matter Content % |
Sugar Content (SC) | Total Phenolic Content (TPC) mg GAE kg−1 |
Antioxidant Activity (TAA) | Total Anthocyanin Content (TAC) |
|||
|---|---|---|---|---|---|---|---|---|
| (Pulp) Brix° |
(Juice) Brix° |
DPPH µmol TE g−1 |
TEAC µmol TE g−1 |
mg cyan kg−1 | mg mal kg−1 | |||
| Year (Yr) | ||||||||
| 2015 (n = 292) | 19.5 ± 0.1 | 17.6 ± 0.1 | 17.8 ± 0.1 | 1583 ± 36 | 78 ± 2 | 7.7 ± 0.3 | 48 ± 4 | 51 ± 4 |
| 2016 (n = 118) | 19.7 ± 0.3 | 17.7 ± 0.2 | 17.9 ± 0.2 | 1551 ± 44 | 77 ± 3 | 5.1 ± 0.4 | 45 ± 6 | 48 ± 7 |
| Production system (PS) | ||||||||
| ORG (n = 210) | 19.8 ± 0.2 | 17.7 ± 0.1 | 17.9 ± 0.2 | 1689 ± 42 | 78 ± 2 | 7.7 ± 0.4 | 39 ± 3 | 41 ± 3 |
| CON (n = 200) | 19.3 ± 0.2 | 17.6 ± 0.1 | 17.8 ± 0.1 | 1452 ± 37 | 77 ± 2 | 6.2 ± 0.3 | 56 ± 6 | 59 ± 6 |
| Production region (PR) | ||||||||
| RSA (n = 220) | 19.8 ± 0.2 | 17.9 ± 0.1 | 18.0 ± 0.1 | 1481 ± 32 | 72 ± 2 | 6.3 ± 0.3 | 48 ± 4 | 51 ± 5 |
| MED. (n = 190) | 19.3 ± 0.2 | 17.3 ± 0.2 | 17.7 ± 0.2 | 1681 ± 49 | 85 ± 3 | 7.7 ± 0.4 | 46 ± 5 | 49 ± 5 |
| Grape type (GT) | ||||||||
| red (n = 174) | 20.6 ± 0.2 | 18.3 ± 0.1 | 18.5 ± 0.1 | 1827 ± 42 | 104 ± 2 | 7.1 ± 0.4 | 98 ± 6 | 103 ± 6 |
| white (n = 236) | 18.8 ± 0.2 | 17.2 ± 0.1 | 17.3 ± 0.1 | 1386 ± 34 | 59 ± 1 | 6.9 ± 0.4 | 10 ± 1 | 11 ± 1 |
|
ANOVA p-values |
||||||||
| Main effects | ||||||||
| Yr | NS | NS | NS | NS | NS | <0.0001 | NS | NS |
| PS | 0.0179 | NS | NS | <0.0001 | NS | 0.0008 | 0.0001 | 0.0001 |
| PR | 0.0270 | 0.0014 | NS | 0.0002 | <0.0001 | 0.0002 | NS | NS |
| GT | <0.0001 | <0.0001 | <0.0001 | <0.0001 | <0.0001 | NS | <0.0001 | <0.0001 |
| Interactions * | ||||||||
| Yr:PS | NS | NS | 0.0797 | 0.0005 | NS | 0.0363 | NS | NS |
| Yr:PR | NS | NS | NS | 0.0327 | NS | <0.0001 | 0.0244 | 0.0237 |
| Yr:GT | 0.0453 | NS | NS | 0.0306 | <0.0001 | NS | NS | NS |
| PS:PR | NS | 0.0233 | 0.0305 | NS | NS | NS | NS | NS |
| GT:PS | NS | NS | NS | NS | NS | NS | <0.0001 3 | <0.0001 3 |
| GT:PR | NS | NS | NS | 0.0004 1 | <0.0001 1 | NS | NS | NS |
| Yr:PR:GT | 0.0858 | NS | 0.0112 2 | NS | 0.0155 2 | <0.0001 2 | 0.0003 | 0.0004 |
| PS:PR:GT | NS | 0.0300 4 | 0.0204 4 | NS | NS | 0.0036 4 | 0.0438 | 0.0434 |
| Yr:PS:PR:GT | NS | NS | NS | NS | NS | NS | 0.0187 5 | 0.0188 5 |
GAE, Gallic acid equivalent; TE, Trolox equivalent; cyan, cyanidin 3-glucoside equivalent; mal, malvidin 3-glucoside equivalent; p-values in italic are for trends (0.1 < p < 0.05); p-values in bold are significant (p < 0.05). * only interactions for which significant results were detected are shown; 1 see Table 3 for interaction means ± SE; 2 see Table 4 for interaction means ± SE; 3 see Table 8 for interaction means ± SE; 4 see Table 4 for interaction means ± SE; 5 see Table 10 for interaction means ± SE.