Cranberry (Vaccinium macrocarpon) Juice Precipitate Pigmentation Is Mainly Polymeric Colors and Has Limited Impact on Soluble Anthocyanin Loss.

Matthew R Dorris,Bradley W Bolling

doi:10.3390/antiox10111788

Abstract

Anthocyanins degrade in fruit juice during storage, reducing juice color quality and depleting the health-promoting components of juice. Common water-soluble products of anthocyanins’ chemical degradation are known, but little is known about the contribution of the insoluble phase to loss processes. Cranberry juice and isolated anthocyanins were incubated at 50 °C for up to 10 days to determine polyphenol profiles and degradation rates. Anthocyanin-proanthocyanidin heteropolymers were analyzed via Matrix Assisted Laser Desorption/Ionization (MALDI)- Time of Flight (TOF) Mass Spectrometry (MS). Formation of soluble protocatechuic acid accounted for 260 ± 10% and insoluble materials for 80 ± 20% of lost soluble cyanidin-glycosides in juice, over-representations plausibly due to quercetin and (epi)catechin in cranberry juice and not observed in the values of 70 ± 20% and 16 ± 6% in the purified anthocyanin system. Loss processes of soluble peonidin-glycosides were better accounted for, where 31 ± 2% were attributable to soluble vanillic acid formation and 3 ± 1% to insoluble materials in cranberry juice and 35 ± 5% to vanillic acid formation and 1.6 ± 0.8% to insoluble materials in the purified anthocyanin system. Free anthocyanins were below quantifiable levels in precipitate, implying most anthocyanins in precipitate were polymeric colors (PCs). PCs in the precipitate included cyanidin- and peonidin-hexosides and -pentosides covalently bonded to procyanidins. Therefore, formation of cranberry juice precipitate does not deplete a large portion of soluble anthocyanins; rather, the precipitate’s pigmentation results from PCs that are also present in the soluble phase.

Highlights

We hypothesized that anthocyanin loss processes are not well accounted for and include established degradation to hydroxybenzoic acids and precipitation; that anthocyanin loss processes differ between whole juice and a simplified system of cranberry juice anthocyanins in buffer because of the known contribution of juice matrix components [33,34,35,36,37]; and that non-specific spectrophotometric methods typically used for juice quality analysis do not accurately and completely capture anthocyanin loss processes
These values are congruent with prior literature describing cranberry anthocyanins as mainly cyanidin- and peonidin- galactosides and -arabinosides followed by glucosides [46,47,48,49,50,51,52,53]
The fate of soluble, precipitated, and hydrolysable phenolics in aged cranberry juice supports the hypothesis that anthocyanin loss processes in juice are not well accounted for and include the formation of hydroxybenzoic acids and loss to precipitation

Summary

Introduction

In addition to the benefits of regular consumption of polyphenols including reduced risk of all-cause mortality, cardiovascular disease mortality [1], certain cancers [2], diabetes [3], and Parkinson disease [4], consumption of anthocyanin-rich juices has shown benefit for chronic inflammation [5], cognitive function [6,7], and blood pressure [6] in human intervention studies. Clinical and epidemiological studies imply that increased anthocyanin and polyphenol intake may be beneficial for reducing the risk of cognitive decline, neurodegenerative diseases, and cardiovascular diseases in part, due to the antioxidant properties of these compounds [8]

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