ENZYMATIC BROWNING IN MARULA FRUIT 1: EFFECT OF ENDOGENOUS ANTIOXIDANTS ON MARULA FRUIT POLYPHENOL OXIDASE

Spectrophotometric assays of marula fruit polyphenol oxidase showed a pronounced lag phase due to the presence of endogenous antioxidants. The total antioxidant capacity (TAC) was quantified in terms of the equivalent concentration of L‐ascorbic acid (L‐ASC.eq). Freeze‐dried marula fruit juice had 2960 mg L‐ASC.eq. per 100 g (pH 4.5) or 1872 mg L‐ASC.eq per 100 g of sample (pH 7.0) assayed with ABTS. The values compare with the known L‐ASC content of 2017 mg per 100 g. The vitamin C content of marula fruit accounts for about 70% of the TAC. The TAC estimate for marula fruit was 20–40 times greater than levels reported in most other fruits.