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Quantitative Fate of Chlorogenic Acid during Enzymatic Browning of Potato Juice
journal contribution
posted on 2013-02-20, 00:00 authored by Carlos-Eduardo Narváez-Cuenca, Jean-Paul Vincken, Harry GruppenThe quantitative fate of chlorogenic acid (ChA) during
enzymatic
browning of potato juice was investigated. Potato juice was prepared
in water without the use of any antibrowning agent (OX treatment). As a control, a potato juice was prepared in the presence
of NaHSO3 (S control). To study the composition
of phenolic compounds in potato in their native states, also a potato
extract was made with 50% (v/v) methanol containing 0.5% (v/v) acetic
acid (MeOH control). Water-soluble low molecular
weight fractions (LMWFs) and high molecular weight fractions (HMWFs)
from S and OX extracts were obtained
by ultrafiltration and dialysis, respectively. Pellets obtained after
the OX treatment and the S and MeOH controls were also analyzed for ChA content. Whereas
in the S-LMWF all ChA was converted to sulfonic acid
adducts, no free ChA was found in the OX-LMWF, indicating
its high reactivity upon enzymatic browning. Analysis of protein in
the HMWFs showed a higher content of “reacted” ChA in OX (49.8 ± 7.1 mg ChA/100 g potato DW) than in S (14.4 ± 1.5 mg ChA/100 g potato DW), as evidenced
by quinic acid release upon alkaline hydrolysis. The presence of quinic
acid in S-HMWF was unexpected, but a mass balance
incorporating the ChA content of LMWF, HMWF, and pellet for the three
extractions suggested that ChA might have been attached to polymeric
material, soluble in the aqueous environment of S but not in that of MeOH. Size exclusion chromatography,
combined with proteolysis, revealed that ChA reacted with patatin
and protease inhibitors to produce brown soluble complexes.