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Abstract: The developmental changes of carbohydrates, organic acids, amino acids and phenolic compounds in ‘Honeycrisp’ apple flesh were investigated using GC–MS and HPLC. A total of 12 carbohydrates, 8 organic acids, 20 amino acids, and 18 phenolic compounds were identified and quantified. Each metabolite showed characteristic changes during fruit development, but in general, concentrations of most sugars and sugar alcohols either increased or remained unchanged whereas concentrations of most organic acids, amino acids and phenolic compounds decreased with fruit development, indicating that most sugars and sugar alcohols are synthesised and/or accumulate at a faster or similar rate relative to fruit growth whereas organic acids, amino acids and phenolics are synthesised and/or accumulate at a slower rate relative to fruit growth. On a whole fruit basis, the content of most metabolites increased with fruit development. In the flesh of mature ‘Honeycrisp’ apple, fructose and sucrose and sorbitol are the major sugars and sugar alcohol; malic acid is the major organic acid; aspartic acid, asparagine, glutamic acid, proline, threonine and γ-aminobutyric acid are the major amino acids; and procyanidin B1, procyanidin B2, chlorogenic acid, catechin and epicatechin are the major phenolic compounds, respectively. [Copyright &y& Elsevier]

To investigate the effects of relative air humidity (AH) on ‘Fuji’ apple ( Malus domestica Borkh.) peel phenolic compounds and pigment coloration, the bagged fruits were bags moved and then exposed to high AH and low AH conditions, respectively. Cyanidin-3-galactoside, the main anthocyanin compound in apple, and 17 other types of phenolic compounds were detected and their concentrations were also compared between high and low AH treated apple peels. We observed that the removal of bags and subsequent re-exposure to sunlight could significantly decrease the concentrations of syringic acid, caffeic acid, ρ-coumaric acid, and quercetin-3-rhamnoside, but increase the concentrations of ferulic acid, quercetin-3-galactoside, quercetin-3-glucoside, quercetin-3-rutinoside, and cyanidin-3-galactoside. Furthermore, high AH samples had higher concentrations of chlorogenic acid, ferulic acid, epicatechin, quercetin-3-rutinoside, and cyanidin-3-galactoside than low AH samples as they were in the similar temperature conditions. These results suggested that high AH conditions could significantly improve coloration and the eating quality of fruits. [ABSTRACT FROM AUTHOR]

Highlights: [•] Phenolic extract from apple peel of ‘Golden Delicious’ can scavenge H2O2. [•] Anthocyanin contributes more to H2O2 scavenging than other phenolic compounds. [•] Less anthocyanin might be used to scavenge H2O2 in vivo than in vitro. [Copyright &y& Elsevier]

Highlights: [•] Responses of phenolics to fruit bagging and the following bag removal were studied. [•] Fruit bagging lowered the phenolic compounds concentration in apple peels. [•] The bag removal increased the concentrations of most phenolic compounds. [•] The compounds responded differently to fruit bagging and the following bag removal. [Copyright &y& Elsevier]