TY - JOUR
T1 - Stability of total phenolic concentration and antioxidant capacity of extracts from pomegranate co-products subjected to in vitro digestion
AU - Fawole, Olaniyi Amos
AU - Opara, Umezuruike Linus
N1 - Publisher Copyright:
© 2016 The Author(s).
PY - 2016/9/13
Y1 - 2016/9/13
N2 - Background: Co-products obtained from pomegranate juice processing contain high levels of polyphenols with potential high added values. From value-addition viewpoint, the aim of this study was to evaluate the stability of polyphenolic concentrations in pomegranate fruit co-products in different solvent extracts and assess the effect on the total antioxidant capacity using the FRAP, DPPH and ABTS+ assays during simulated in vitro digestion. Methods: Pomegranate juice, marc and peel were extracted in water, 50% ethanol (50%EtOH) and absolute ethanol (100%EtOH) and analysed for total phenolic concentration (TPC), total flavonoids concentration (TFC) and total antioxidant capacity in DPPH, ABTS+ and FRAP assays before and after in vitro digestion. Results: Total phenolic concentration (TPC) and total flavonoid concentration (TFC) were in the order of peel>marc>juice throughout the in vitro digestion irrespective of the extraction solvents used. However, 50% ethanol extracted 1.1 to 12-fold more polyphenols than water and ethanol solvents depending on co-products. TPC and TFC increased significantly in gastric digests. In contrast, after the duodenal phase of in vitro digestion, polyphenolic concentrations decreased significantly (p<0.05) compared to those obtained in gastric digests. Undigested samples and gastric digests showed strong and positive relationships between polyphenols and the antioxidant activities measured in DPPH, ABTS+ and FRAP assays, with correlation coefficients (r 2) ranging between 0.930-0.990. In addition, the relationships between polyphenols (TPC and TFC) and radical cation scavenging activity in ABTS+ were moderately positive in duodenal digests. Conclusion: Findings from this study showed that concentration of pomegranate polyphenols and the antioxidant capacity during in vitro gastro-intestinal digestion may not reflect the pre-digested phenolic concentration. Thus, this study highlights the need to provide biologically relevant information on antioxidants by providing data reflecting their stability and activity after in vitro digestion.
AB - Background: Co-products obtained from pomegranate juice processing contain high levels of polyphenols with potential high added values. From value-addition viewpoint, the aim of this study was to evaluate the stability of polyphenolic concentrations in pomegranate fruit co-products in different solvent extracts and assess the effect on the total antioxidant capacity using the FRAP, DPPH and ABTS+ assays during simulated in vitro digestion. Methods: Pomegranate juice, marc and peel were extracted in water, 50% ethanol (50%EtOH) and absolute ethanol (100%EtOH) and analysed for total phenolic concentration (TPC), total flavonoids concentration (TFC) and total antioxidant capacity in DPPH, ABTS+ and FRAP assays before and after in vitro digestion. Results: Total phenolic concentration (TPC) and total flavonoid concentration (TFC) were in the order of peel>marc>juice throughout the in vitro digestion irrespective of the extraction solvents used. However, 50% ethanol extracted 1.1 to 12-fold more polyphenols than water and ethanol solvents depending on co-products. TPC and TFC increased significantly in gastric digests. In contrast, after the duodenal phase of in vitro digestion, polyphenolic concentrations decreased significantly (p<0.05) compared to those obtained in gastric digests. Undigested samples and gastric digests showed strong and positive relationships between polyphenols and the antioxidant activities measured in DPPH, ABTS+ and FRAP assays, with correlation coefficients (r 2) ranging between 0.930-0.990. In addition, the relationships between polyphenols (TPC and TFC) and radical cation scavenging activity in ABTS+ were moderately positive in duodenal digests. Conclusion: Findings from this study showed that concentration of pomegranate polyphenols and the antioxidant capacity during in vitro gastro-intestinal digestion may not reflect the pre-digested phenolic concentration. Thus, this study highlights the need to provide biologically relevant information on antioxidants by providing data reflecting their stability and activity after in vitro digestion.
KW - By-product
KW - DPPH
KW - Pepsin
KW - Polyphenols
KW - Pomegranate
KW - Value-addition
UR - http://www.scopus.com/inward/record.url?scp=84987625578&partnerID=8YFLogxK
U2 - 10.1186/s12906-016-1343-2
DO - 10.1186/s12906-016-1343-2
M3 - Article
C2 - 27618992
AN - SCOPUS:84987625578
SN - 1472-6882
VL - 16
JO - BMC Complementary and Alternative Medicine
JF - BMC Complementary and Alternative Medicine
IS - 1
M1 - 358
ER -