Determination of (Total) Phenolics and Antioxidant Capacity in Food and Ingredients

Phenolic compounds and other antioxidants are of interest since they have the potential to stabilize food products against lipid deterioration and may have beneficial health effects. Thus, there is a demand to measure phenolic compounds in food products and to evaluate the antioxidant capacity of individual food constituents, extracts, and ingredients. Assays described in this chapter are of four types: (total) phenolics assays, hydrogen atom transfer-based antioxidant capacity assays, single electron transfer-based antioxidant capacity assays, and accelerated lipid oxidation assays. Methods to determine the total phenolic contents of food products such as the Folin-Ciocalteu assay are unspecific and do not, depending on the overall composition of the food product, necessarily reflect the phenolic contents. Therefore, wherever possible, it is advised to study individual phenolic compounds by using various chromatography approaches. This chapter includes cautions regarding the types of antioxidant capacity assays used to screen compounds for delaying lipid oxidation and potential health benefits.