# Phenolic Profiling of Five Different Australian Grown Apples
## 3 Results and Discussion
### Phenolic Compounds Profile by LC-MS/MS Analysis
#### 3.4.2. Flavonoids  
A total of 52 Flavonoids were identified in the five apple samples including anthocyanins (8), dihydrohalcones (3), dihydrohalvonols (3), flavanols (9), flavones (4), flavanones (7), flavonols (10), and Isoflavonoids (8). Compound **31** (Cyanidin 3.5-O-diglucoside) and compound **33** (Delphinidin 3-O-glucosyl-glucose) were both detected in the positive mode of ionization with the precursor ions at \(m/z\) 612.1693 and \(m/z\) 628.1648, respectively. The MS/MS experiment allowed the further identification of these compounds based on the peaks after removal of the sugar moieties for both compounds [55]. Compound **36** and compound **37** were tentatively characterised as 3-hydroxyphloretin 2\({}^{\prime}\)-O-glucose and 3-hydroxyphloretin 2\({}^{\prime}\)-O-xylosyl-glucose present in negative mode of ionisation with precursor ions at \(m/z\) 451.1249 and \(m/z\) 583.1665, respectively. 3-hydroxyphloretin 2\({}^{\prime}\)-O-glucose was confirmed by fragment ions at \(m/z\) 289 [M-H-glucoseide] and \(m/z\) 273 [M-H-phloretin aglycon] [56] identified in Pink Lady, Royal Gala, Fuji and Smitten apples. Whereas, 3-Hydroxyphloretin 2\({}^{\prime}\)-O-xylosyl-glucose was identified by fragment ions at \(m/z\) 289, due to the loss of xylosyl-glucose disaccharide (132 + 162 Da) [57] observed in Royal Gala apples. Phloridzin (compound **38**) with precursor ion at [[[M-H]\({}^{-}\), \(m/z\) 435.1284], and confirmed by product ions at \(m/z\) 273 due to the loss of glucoside (162 Da) [58] identified in Pink Lady, Royal Gala, Fuji and Smitten apples. [PERSON] et al. [58] reported the presence of phloridzin in apples. Three flavanols derivatives (Compound **44**, **46**, **48**) were all detected in four samples including Pink Lady, Royal Gala, Fuji and Smitten apples. Compound **44**, **46**, **48** with negative mode of ionisation with precursor ions at \(m/z\) 577.1333, \(m/z\) 289.0706 and \(m/z\) 865.1961 were tentatively characterised as procyanidin dimer B1, (+)-catechin and procyanidin trimer C1 respectively. The compound procyanidin trimer C1 was confirmed by product ions at \(m/z\) 739, \(m/z\) 713 and \(m/z\) 695, due to the loss of heterocyclic ring fission(HRF) reaction (126 Da), loss of retro-Diels-Alder (RDA) (152 Da) and loss of H\({}_{2}\)O [59]. While the loss of phloroglucinol (126 Da) from the precursor ion confirmed the presence of procyanidin dimer B1 [60]. Whereas, (+)-catechin compound confirmed based on the fragment ions at \(m/z\) 245, \(m/z\) 205 and \(m/z\) 179, due to corresponding loss of CO\({}_{2}\) (44 Da), flavonoid A ring (84 Da) and flavonoid B ring (110 Da) from the precursor ion, respectively [50]. Previously [PERSON] et al. [61] reported the presence of (+)-catechin in apple varieties. (+)-catechin has a positive health benefit including scavenging free radicals, delaying aging and benefitting the intestinal microbes [62]. Compound **51** (hesperetin 3\({}^{\prime}\),7-O-diglucuronide) and compound **53** (narirutin) were found both in negative ionization modes based on the precuox ions at \(m/z\) 653.1361 and \(m/z\) 579.1710, respectively. Compound **51** was confirmed by the product ion at \(m/z\) 477 [M-H-glucuronide, loss of 176 Da], \(m/z\) 301 [M-H-2 glucuronide, loss of 352 Da], \(m/z\) 286 [M-H-2 glucuronide-CH\({}_{3}\), loss of 367 Da] and \(m/z\) 242 [M-H-2 glucuronide-OCH\({}_{2}\)-CHO] [63], while compound **53** was confirmed by loss of neohesperidase moiety (308 Da) [64] from the precursor ion. In our study compound **51** was identified in Smitten and Pink Lady whereas compound **53** was identified in Royal Gala and Red Delicious. To our best knowledge it was first time detected in Australian grown apples. Apigenin 7-O-glucuron (Compound **56**) and crissineol (compound **58**) were tentatively characterised in negative mode of ionisation at \(m/z\) 447.0930 and \(m/z\) 345.0962, respectively.