Polyphenols are a large group of naturally occurring plant compounds found in berries, dark honeys, herbs and some grains, measured in trade to support quality assessment and nutritional or authenticity claims.
In trade practice
Total polyphenol content is typically determined by the Folin-Ciocalteu method and reported as gallic-acid equivalents per kilogram of product. Buyers of berry concentrates, honey and herbal ingredients may request polyphenol data alongside a certificate of analysis to verify batch consistency. Suppliers should note that results vary with cultivar, harvest date and processing method, so a single reference value in a specification can be difficult to hold across seasons.
In a specification
A specification may state a minimum total polyphenol content expressed as gallic-acid equivalents per kilogram, with the analytical method named to ensure comparable results between laboratories.