Fatty acid composition in relation to chilling susceptibility of blood orange cultivars at different storage temperatures

Anthocyanin in blood oranges: a review on postharvest approaches for its enhancement and preservation

Anthocyanin concentration is considered an important fruit quality index of blood oranges and has gained popularity among consumers due to its antioxidant capacity, therapeutic properties, and prevention of some human diseases. Anthocyanin biosynthesis occurs in the cytoplasmic face of the endoplasmic reticulum by multi-enzymes complexes through the flavonoid pathway. Polyphenoloxidase (PPO) and β-glucosidase (anthocyanase) are the enzymes responsible for anthocyanin degradation. Blood oranges are cold-dependent for anthocyanin biosynthesis and accumulation, and thus, the low temperature of storage can enhance anthocyanin concentration and improve internal fruit quality. In addition, anthocyanin accumulation can be accelerated by postharvest technologies, either physical treatments or chemical elicitors. However, low temperatures can induce chilling injury (CI) incidence in blood oranges. Postharvest chemical elicitors treatments can enhance anthocyanin accumulation and prevent CI. This review provides the most updated information about postharvest tools modulating the anthocyanin content, and the role of enhancing and preserving pigmentation to produce blood orange with the highest quality standards.

Exogenous Application of Glycine Betaine Maintains Bioactive Compounds, Antioxidant Activity, and Physicochemical Attributes of Blood Orange Fruit During Prolonged Cold Storage

Exogenous application of glycine betaine (GB) was evaluated on bioactive compounds, antioxidant activity, and physicochemical attributes of blood orange fruit cv. Moro at 3°C for 90 days. Vacuum infiltration (30 kPa) of GB was applied at 15 and 30 mM for 8 min. Parameters were measured after 1, 30, 60, and 90 days of storage plus 2 days at 20°C to simulate the shelf-life period. GB treatments significantly reduced weight and firmness losses in "Moro" blood orange fruit during cold storage. GB treatment maintained a higher concentration of organic acids (citric, malic, succinic, and oxalic acids) and sugars (sucrose, glucose, and fructose), especially for the higher GB doses (30 mM). During storage, GB treatments enhanced total anthocyanin concentration, total phenolic content, and total antioxidant activity. With respect to enzyme activities, the application of exogenous GB showed increases in catalase (CAT), ascorbate peroxidase, superoxide dismutase, phenylalanine ammonia-lyase, while suppressing the polyphenol oxidase activity. Overall, the most effective treatment was 30 mM GB leading to maintaining bioactive compounds, antioxidant activity, and quality in "Moro" blood orange fruit during long-term storage. The positive results would permit the use of GB as a postharvest tool to maintain the quality attributes of blood orange fruit.

Physicochemical Changes, Peel Colour, and Juice Attributes of Blood Orange Cultivars Stored at Different Temperatures

Changes in physicochemical traits, peel colour, and juice attributes of four blood orange cultivars (‘Moro’, ‘Tarocco’, ‘Sanguinello’, and ‘Sanguine’) were evaluated during 180 days at 2 and 5 °C plus 2 days at 20 °C for shelf life. ‘Tarocco’ had the lowest weight and firmness losses at both temperatures during storage. Titratable acidity (TA) at 5 °C was higher than 2 °C, with ‘Sanguinello’ and ‘Tarocco’ showing the highest and lowest TA, respectively. Juice content decreased during storage at both temperatures, although ‘Sanguinello’ had the highest juice content among the tested cultivars. Peel colour parameters including L* (lightness), b*, hue angle (h°), and chroma (C*) decreased during cold storage, while a* and citrus colour index (CCI) increased in all cultivars at both temperatures. The order for CCI was ‘Tarocco’ > ‘Moro’ > ‘Sanguinello’ > ‘Sanguine’. Overall, prolonged storage at 5 °C was considered as optimum temperature for all cultivars, although ‘Sanguinello’ cultivar had a better aptitude for the citrus juice industry.