Anthocyanins tend to be the main polyphenolics in purple grapes whereas flavan-3-ols (i.e. catechins) are the more abundant phenolic in white varieties. Total phenolic content, a laboratory index of antioxidant strength, is higher in purple varieties due almost entirely to anthocyanin density in purple grape skin compared to absence of anthocyanins in white grape skin. It is these anthocyanins that are attracting the efforts of scientists to define their properties for human health. Phenolic content of grape skin varies with cultivar, soil composition, climate, geographic origin, and cultivation practices or exposure to diseases, such as fungal infections. COUNT 5
QSN1 What are the most abundant polyphenolics in purple grapes? ANS1 Anthocyanins QSN2 What is the laboratory index of antioxidant strength in grapes known as?  ANS2 Total phenolic content QSN3 What content of a grapes skin can be affected by soil composition, climate, and cultivation practices?  ANS3 Phenolic content QSN4 Why causes antioxidant strength to be higher in purple grapes? ANS4 anthocyanins QSN5 What is the main phenolic in white grapes? ANS5 flavan-3-ols