Journal of Food Bioactives, ISSN 2637-8752 print, 2637-8779 online
Journal website www.isnff-jfb.com

Original Research

Volume 11, September 2020, pages 66-74

Influence of processing on the phenolic compounds of feijoa pulp (Feijoa sellowiana)

Figures

Figure 1.
Figure 1. Distribution of the cloud of variables and observations, obtained in the Principal Component Analysis (PCA) from the results of antioxidant activity, phenolic compounds and flavonoids of the feijoa pulp submitted to refrigeration (control), irradiation (2.0 kGy) and pasteurization (85 °C/5 min) during storage (5 °C, 28 days). Variables: FLAV = total flavonoids (mg of quercetin equivalents 100 g−1 of pulp); DPPH = DPPH radical scavenging activity (µM of trolox equivalents g−1 of pulp); TPC = Total phenolic compounds (mg of gallic acid equivalents g−1 of pulp); ABTS = ABTS radical scavenging assay (µM of trolox equivalents g−1 of pulp). Observations: C1 = control stored for 1 day; C7 = control stored for 7 days; C14 = control stored for 14 days; C21 = control stored for 21 days; C28 = control stored for 28 days; I1 = irradiated (2.0 kGy) stored for 1 day; C7 = irradiated (2.0 kGy) stored for 7 days; C14 = irradiated (2.0 kGy) stored for 14 days; C21 = irradiated (2.0 kGy) stored for 21 days; C28 = irradiated (2.0 kGy) stored for 28 days.
Figure 2.
Figure 2. Distribution of the cloud of variables and observations, obtained in the Principal Component Analysis (PCA) from the phenolic compounds identified and quantified (µg g−1) in feijoa pulp subjected to refrigeration (control), irradiation (2.0 kGy) and pasteurization (85 °C/5 min). Variables: Shik = Shikimic acid; Caff = Caffeic acid; Ella = Ellagic acid; Quer = Quercetin; Gall = Gallic acid; Quin = Quinic acid. Observations: C = refrigerated feijoa pulp (control); I = irradiated feijoa pulp (2.0 kGy); P = pasteurized feijoa pulp (85 °C/5 min).

Tables

Table 1. Antioxidant activity, phenolic compounds and flavonoids of feijoa pulp subjected to refrigeration (control), irradiation (2.0 kGy) and pasteurization (85 °C/5 min) during 28 days of refrigerated storage (mean ± standard deviation, n = 3)
 
Storage period (days)
Treatments17142128
DPPH radical scavenging activity (µM of trolox equivalents g−1 of pulp)
Control53.74 ± 8.9539.20 ± 3.7820.53 ± 2.6925.36 ± 2.7722.97 ± 2.10
Irradiation48.92 ± 2.0646.06 ± 4.3033.89 ± 1.3121.41 ± 3.4226.57 ± 0.57
Pasteurization49.61 ± 0.6937.74 ± 4.0941.84 ± 6.7039.95 ± 7.0549.60 ± 0.58
ABTS radical scavenging assay (µM of trolox equivalents g−1 of pulp)
Control42.87 ± 6.1132.89 ± 4.3834.24 ± 6.9626.98 ± 1.2028.98 ± 2.61
Irradiation39.34 ± 5.2542.21 ± 2.0547.07 ± 0.8023.72 ± 2.7531.47 ± 0.30
Pasteurization41.63 ± 1.7255.31 ± 5.3959.26 ± 6.0558.15 ± 0.5959.40 ± 0.37
Total phenolic compounds (mg of gallic acid equivalents g−1 of pulp)
Control10.21 ± 0.756.01 ± 0.845.09 ± 0.915.09 ± 0.914.98 ± 0.61
Irradiation9.75 ± 0.787.77 ± 0.286.54 ± 0.146.54 ± 0.144.23 ± 0.84
Pasteurization12.64 ± 0.4710.35 ± 1.2112.42 ± 1.1012.42 ± 1.106.20 ± 0.07
Total flavonoids (mg of quercetin equivalents 100 g−1 of pulp)
Control68.40 ± 9.3942.50 ± 1.6740.25 ± 2.2447.99 ± 5.3421.01 ± 0.47
Irradiation53.82 ± 4.7444.33 ± 7.3040.46 ± 2.0831.51 ± 3.1618.65 ± 5.99
Pasteurization58.48 ± 7.8230.89 ± 4.3629.17 ± 3.4526.74 ± 2.1213.56 ± 2.70

 

Table 2. Phenolic compounds identified and quantified (µg g−1 of pulp) in feijoa pulp subjected to refrigeration (control), irradiation (2 kGy) and pasteurization (85 °C/5 min)
 
Phenolic compoundControlIrradiationPasteurization
LQ (limit of quantification) = 6.09 10−3 mg g−1 of extract; LD (limit of detection) = 3.10 10−6 mg g−1 of extract.
1,3-Dicaffeoylquinic acidLDLDLD
1,5-Dicaffeoylquinic acidLDLDLD
Caffeic acid14.9 ± 0.00119.0 ± 0.00125.9 ± 0.001
Chlorogenic acidLQLQLQ
p-Coumaric acidLQLQLQ
Ellagic acid290.0 ± 0.004237.0 ± 0.004383.0 ± 0.003
Ferulic acidLDLDLD
Gallic acid80.1 ± 0.00477.2 ± 0.003673.0 ± 0.003
Quinic acid217.0 ± 0.007269.0 ± 0.007204.0 ± 0.006
Shikimic acid21.9 ± 0.000127.2 ± 0.00123.3 ± 0.0001
KaempferolLQLQLQ
Quercetin6.24 ± 0.0033LQ16.1 ± 0.003
RutinLQLQLQ