At the initial of storage time, the content of vitamin C of MFclarified
pineapple juice was 26.32 ± 1.32 mg/100 mL. This value
was slightly less than that found in the fresh pineapple juice
(28.67 ± 1.8 mg/100 mL). The results indicated that MF is an effective
method that retains vitamin C in pineapple juice. Vitamin C
content sharply decreased (P < 0.05) during the first month of the
storage (Fig 6), presumably, due to the complete degradation of
L-ascorbic acid while the dehydroascorbic acid can still be maintained
in the juice. Choi et al. (2002) found similar results when
they studied the ascorbic acid retention in blood orange juice during
refrigerated storage. The researchers found, that the L-ascorbic
acid completely degraded within 5 weeks. In the present study, the
reduction of vitamin C content stored at 6 months and at 4, 27 and
37 C of clarified pineapple juice were 60.7%, 70.3% and 74.8%,