Changes in chokeberry (Aronia melanocarpa L.) polyphenols during juice processing and storage

Area of Science:

• Food Science
• Nutritional Chemistry
• Agricultural Science

Background:

• Chokeberries are rich in polyphenols, including anthocyanins, proanthocyanidins, hydroxycinnamic acids, and flavonols.
• The stability and fate of these valuable compounds during juice processing and storage are not well understood.

Purpose of the Study:

• To determine the stability of key polyphenols in chokeberry juice throughout processing and 6 months of storage.
• To quantify losses and identify factors affecting polyphenol retention in chokeberry juice.

Main Methods:

• Analysis of anthocyanins, total proanthocyanidins, hydroxycinnamic acids, and flavonols at different processing stages (pressing, thermal treatment).
• Monitoring polyphenol levels during 6 months of juice storage at 25 °C.
• Assessing changes in polymeric color values during storage.

Main Results:

• Flavonols, proanthocyanidins, and hydroxycinnamic acids showed higher retention than anthocyanins.
• Major losses of polyphenols occurred during seed and skin removal post-pressing.
• Thermal treatments significantly degraded anthocyanins, increasing protocatechuic acid and phloroglucinaldehyde.
• Anthocyanins declined linearly during 6 months of storage, forming polymeric structures.

Conclusions:

• Chokeberry juice processing, particularly thermal treatments and seed/skin removal, leads to significant anthocyanin degradation.
• While other polyphenols are relatively stable, anthocyanin losses reduce the juice's potential health benefits.
• Understanding these stability issues is crucial for optimizing chokeberry juice production and preserving its nutritional value.