Total Phenolic Concentration and Browning Susceptibility in a Collection of Different Varietal Types and Hybrids of Eggplant: Implications for Breeding for Higher Nutritional Quality and Reduced Browning

Abstract

<jats:p>Phenolic compounds have numerous beneficial effects on human health. In consequence, the development of new varieties with higher content of phenolics is of interest for the improvement of the nutritional quality of eggplant (<jats:italic>Solanum melongena</jats:italic> L.). However, the oxidation of eggplant phenolics causes browning of the cut surfaces of the fruit and reduces its apparent quality. The authors investigated the relationship among, as well as the variation and heritability of, the content of phenolics, ascorbic acid, and soluble solids; pH; and the degree of browning and color difference of the cut surface of the fruit flesh in a collection of 69 eggplant varieties. These included landraces from different origins, commercial varieties, experimental hybrids, and four accessions of the related <jats:italic>S. aethiopicum</jats:italic> L. and <jats:italic>S. macrocarpon</jats:italic> L. species. Analyses of variance revealed significant differences among the materials studied for all traits considered. The concentration of phenolics in <jats:italic>S. melongena</jats:italic> spanned a threefold range, although the highest (1122 mg·kg<jats:sup>−1</jats:sup>) and lowest (134 mg·kg<jats:sup>−1</jats:sup>) concentrations of phenolics were found in <jats:italic>S. macrocarpon</jats:italic> and <jats:italic>S. aethiopicum</jats:italic> respectively. Concentrations of ascorbic acid were very low, a mean 27 times lower than those of phenolics, and soluble solids content ranged from 3.60% to 6.60% with a pH that ranged from 5.01 to 5.93. Commercial varieties had, as a mean, a 20% lower concentration of phenolics than landraces, as well as a lower degree of browning and color difference. Positive correlations existed between phenolic concentration and degree of browning (r = 0.388) and color difference (0.477), although only 15.1% and 22.8% of the total variation in degree of browning and color difference, respectively, could be attributed to variation in phenolics. Ascorbic acid, soluble solids content, and pH were not correlated to either degree of browning or color difference. The heritability was moderate for phenolic concentration (0.50) and high for degree of browning (0.71) and color difference (0.82). The information obtained indicates that there are opportunities for the development of new varieties with a high concentration of phenolics and low or moderate browning.</jats:p>

Characterization of interspecific hybrids and first backcross generations from crosses between two cultivated eggplants (Solanum melongena and S. aethiopicum Kumba group) and implications for eggplant breeding

“…Measurements of fruit phenolics content in the parental lines confirms the occurrence of low total fruit phenolics in S. aethiopicum relative to S. melongena (Stommel and Whitaker 2003;Prohens et al 2007;Mennella et al 2010) and denote that S. melongena could be utilized for improving the phenolics content of S. aethiopicum. Low fruit phenolics in interspecific hybrids suggests dominance of the S. aethiopicum alleles.…”

“…0°20 0 11 00 W) in a completely randomized design. A completely randomized design was used instead of a block design because the plot is quite uniform and previous experiments using block designs showed no block effect (Prohens et al 2007;Muñoz-Falcón et al 2008). Plants were spaced 1 m between rows and 0.8 m apart within the row and drip irrigated.…”

“…b* 2 )) 0.5 , where DW is the distance to the pure white color. The difference between DW at 10 min (DW 10 ) and at 0 min after the fruit was cut (DW 0 ), i.e., the increase in the distance to pure white, was used as a measure of degree of browning (DB) suffered by the fruit (DB = DW 10 -DW 0 ) (Prohens et al 2007). DB data of individual fruits were used to obtain an average DB value per plant.…”

“…Lester (1986) suggested that these three species together serve mutually as secondary genepools. For example, S. melongena could be a source of variation for fruit size and shape in the gboma and scarlet eggplants and might also be useful to increase fruit phenolic antioxidant content of S. aethiopicum, which usually presents concentrations much lower than those of S. melongena (Stommel and Whitaker 2003;Prohens et al 2007).…”

The effect of grinding at various vacuum levels on the color, phenolics, and antioxidant properties of apple

“…Color changes are likely due to the onset of enzymatic browning triggered by the grinding. Prohens, Rodríguez-Burruezo, Dolores Raiǵ on, and Nuez (2007) showed that there were significant correlations amongst phenolics, color difference, and degree of browning. Nicoli, Calligaris, and Manzocco (2000) reported that browning was associated with a decrease in antioxidant activity of apples.…”