LC for Characterizing Qualitative Traits in Blood Oranges

Scientists from the Department of Agriculture, Food and Environment at the University of Catania (Italy) and the Plant Science and Microbiology Department of Miguel Hernández University (Alicante, Spain), conducted an investigation of the accumulation of primary and secondary metabolites, including bioactive compounds, to characterize the qualitative traits of blood oranges at the time of harvest. Simple sugars were identified and quantified by liquid chromatography (LC), and organic acids, polyphenols, and flavonoids by spectrophotometric analysis. A paper presenting their finds was recently published in Foods (1).

Blood sweet oranges (Citrus sinensis (L.) Osbeck) differs from blond oranges primarily by the presence of red color in the flesh of the fruit and the peel. This pigmentation is associated with the presence of anthocyanins, water-soluble pigments that belong to the larger family of phenols. The amount of these pigments is remarkably influenced by several factors, including cultivar, rootstocks, maturity stage, site of cultivation, and climatic conditions (2-5). While the consumption of blood oranges has increased in recent years, especially in Europe (6), they are cultivated only in a few citrus-producing countries such as Italy (historically the main blood orange-producing country in Europe) and Spain (where cultivation has increased to the point that they are now the European country producing the most), where climatic conditions favor the biosynthesis of the red pigment (6-11).

The experiment on the evolution of the maturation of blood oranges was carried out in three different sites situated in Spain and Italy, with four varieties of orange present in all three plots (Tarocco Rosso, Tarocco Scirè, Moro, and Sanguinelli), and a fifth sampled only in plots 1 and 3 (Tarocco Ippolito). Thirty representative pooled fruits from each variety for each plot were sampled, collected, individually weighed, measured, and then used for juice extraction. Individual organic acids and sugars were quantified using three juice samples for each variety as described by a previous study (12). Briefly, one milliliter of the centrifuged juice was passed through a filter and then injected into a high-performance liquid chromatography (HPLC) system (1).

In the article, the authors state that their work demonstrates the effect of environmental conditions on the primary and secondary metabolites of different blood orange varieties was demonstrated. Different accumulations of sugars and organic acids were observed in the three plots studied, with the genotypes in plot 3 accumulating the highest content of single sugars and ascorbic acid. Regarding pigmentation, Moro and T. Ippolito reached the highest anthocyanin content in plots 1 and 3, while Moro and T. Rosso had the highest amounts in plot 2, supporting the prevalent role of the genotype in the pigmentation of blood oranges. The effects of the environment on juice biochemical compounds and antioxidant activity were confirmed as well. Overall, Moro and Sanguinelli confirm their suitability for juice extraction due to the high pigmentation, with Tarocco lines being more adaptable for fresh consumption (1).

Blood oranges in a basket. © magic_cinema - stock.adobe.com

References

1. Modica, G.; Legua, P.; La Malfa, S.; Gentile A.; Continella, A. Qualitative Traits and Antioxidant Properties of Blood Oranges Are Affected by the Genotype and the Climatic Conditions. Foods 2024, 13 (19), 3137. DOI: 10.3390/foods13193137

2. Ferlito, F.; Nicolosi, E.; Gentile, A.; Lo Piero, A.R.; Squadrito, M.; Continella, A. Responses of Four Winegrape Varieties to Managed Water Stress and Partial Defoliation in an Arid Environment. Vitis 2014, 53, 73–80.

3. Lo Piero, A.R.; Puglisi, I.; Rapisarda, P.; Petrone, G. Anthocyanins Accumulation and Related Gene Expression in Red Orange Fruit Induced by Low Temperature Storage. J. Agric. Food Chem. 2005, 53, 9083–9088.DOI: 10.1021/jf051609s

4. Lana, G.; Modica, G.; Las Casas, G.; Siracusa, L.; La Malfa, S.; Gentile, A.; Sicilia, A.; Distefano, G.; Continella, A. Molecular Insights into the Effects of Rootstocks on Maturation of Blood Oranges. Horticulturae 2021, 7, 468. DOI: /10.1016/j.jfca.2021.104246

5. Modica, G.; Pannitteri, C.; Di Guardo, M.; La Malfa, S.; Gentile, A.; Ruberto, G.; Pulvirenti, L.; Parafati, L.; Continell, A.; Siracusa, L. Influence of Rootstock Genotype on Individual Metabolic Responses and Antioxidant Potential of Blood Orange cv. Tarocco Scirè. J. Food Compos. Anal. 2022, 105, 104246. 10.1016/j.jfca.2021.104246

6. Simons, T.J.; McNeil, C.J.; Pham, V.D.; Suh, J.H.; Wang, Y.; Slupsky, C.M.; Guinard, J.X. Evaluation of California-Grown Blood and Cara Cara Oranges Through Consumer Testing, Descriptive Analysis, and Targeted Chemical Profiling. J. Food Sci. 2019, 84, 3246–3263. DOI: 10.1111/1750-3841.14820

7. Continella, A.; Pannitteri, C.; La Malfa, S.; Legua, P.; Distefano, G.; Nicolosi, E.; Gentile, A. Influence of Different Rootstocks on Yield Precocity and Fruit Quality of ‘Tarocco Scirè’ Pigmented Sweet Orange. Sci. Hortic. 2018, 230, 62–67. DOI: 10.1016/j.scienta.2017.11.006

8. Cebadera-Miranda, L.; Domínguez, L.; Dias, M.I.; Barros, L.; Ferreira, I.C.; Igual, M.; Martínez-Navarrete, N.; Fernández-Ruiz, V.; Morales, P.; Cámara, M. Sanguinello andTarocco (Citrus sinensis [L.] Osbeck): Bioactive Compounds and Colour Appearance of Blood Oranges. Food Chem. 2019, 270, 395–402. DOI: 10.1016/j.foodchem.2018.07.094

9. Habibi, F.; Guillén, F.; Serrano, M.; Valero, D. Postharvest Treatment with Glycine Betaine Enhances Chilling Tolerance of Blood Orange Fruit by Increasing Antioxidant Defence Systems and Osmoregulation During Cold Storage. Sci. Hortic. 2022, 305, 111352. DOI: 10.1016/j.scienta.2022.111352]

10. Legua, P.; Modica, G.; Porras, I.; Conesa, A.; Continella, A. Bioactive Compounds, Antioxidant Activity and Fruit Quality Evaluation of Eleven Blood Orange Cultivars. J. Sci. Food Agric. 2022, 102, 2960–2971. DOI: 10.1002/jsfa.11636

11. Caruso, M.; Ferlito, F.; Licciardello, C.; Allegra, M.; Strano, M.C.; Di Silvestro, S.; Russo, M.P.; Paolo, D.P.; Caruso, P.; Las Casas, G.; et al. Pomological Diversity of the Italian Blood Orange Germplasm. Sci. Hortic. 2016, 213, 331–339. DOI: 10.1016/j.scienta.2016.10.044

12. Legua, P.; Forner, J.; Hernández, F.; Forner-Giner, M. Physico-Chemical Properties of Orange Juice from Ten Rootstocks Using Multivariate Analysis. Sci Hortic. 2013, 160, 268–273. DOI: 10.1016/j.scienta.2013.06.010