Blueberry

• The blueberry bush (Vaccinium corymbosum) belongs to the Ericaceae family.
• It is native to North America (Rodriguez-Saona, 2019).

PHYSICAL AND ORGANOLEPTIC CHARACTERISTICS

• The blueberry is a small round fruit. Its epidermis is covered with a hydrophobic surface with a matt appearance, composed of the cuticle and an epicuticular wax. The thicker this hydrophobic surface, the better the fruit retains its physical and nutritional qualities during harvesting and storage (Sapers, 1985).
• The skin (epidermis + hydrophobic surface) is blue and the flesh yellowish white (Michalska, 2015).
• The blue colour of the skin is due to the presence of anthocyanins. At least 14 anthocyanins and 3 acetylated anthocyanins have been quantified, with delphidin 3-galactoside, petunidin 3-galactoside and malvidin 3-galactoside being the most represented (Cho, 2004). Chlorogenic acid, also present, is a co-pigment that intensifies the colour of the anthocyanins (Mazza, 1990).
• Conversely, the “absence of colour” of the flesh is characterised by the virtual absence of anthocyanins (Lee, 2006).
• During ripening, the blueberry becomes less and less acidic, with a titratable acidity that decreases. Malic acid is the predominant organic acid, responsible for the acidity of the fruit (Castrejón, 2008).
• The content of proanthocyanidins, responsible for the bitter taste of unripe fruits, also decreases with ripening (Zifkin, 2012).
• Ripe blueberry has a sweet taste, the intensity of which varies according to the cultivar (Mennella, 2017). This sweetness is due to the presence of sucrose, but also fructose, galactose and glucose (Montecchiarini, 2018).
• Concerning the aroma of blueberries, more than 120 volatile compounds have been listed (Sater, 2020). Among them, 1-penten-3-ol, hexanal, (E)-2-hexenal, (E)-2-hexen-1-ol, and linalool are thought to play significant roles. During ripening, the average amount of all volatile compounds increases (Gilbert, 2013).

COMPOSITION CHARACTERISTICS (excluding macronutrients, vitamins and minerals)

• Blueberry contains polyphenols: flavonoids (proanthocyanidins and flavonols), phenolic acids (gallic, syringic, vanillic and hydroxycinnamic acids) and stilbenes derivatives The polyphenol content can be up to 304 mg/100 g of fresh fruit, depending on the cultivar and ripeness. They are mainly present in the outer layers (the skin and just under the epidermis). Only a small amount is found in the flesh (Michalska, 2015).
• While anthocyanin content increases with ripening, the contents of proanthocyanidins, flavonols and hydroxycinnamic acids, a family of phenolic acids, decrease (Castrejón, 2008; Zifkin, 2012). The ripe fruit therefore contains mostly anthocyanins with a content of up to 495 mg/100 g of fruit (Michalska, 2015).
• The polyphenols present have antioxidant and protective activity, believed to provide many health benefits. They possess the following activity:
  • Protection against lipid peroxidation and other types of oxidative damage;
  • Protection against DNA mutations, which hinder their transformation into cancer cells;
  • antitumour;
  • anti-inflammatory;
  • immunomodulatory;
  • neuroprotective;
  • prevention of cardiovascular pathologies;
  • prevention of obesity and diabetes;
  • antimicrobial (Silva, 2018).
• Blueberry also contains a notable amount of organic acids, such as malic acid, citric acid and ascorbic acid or vitamin C, which is also known as a powerful antioxidant (Castrejón, 2008; Silva, 2018).