Application of Purified MnP for the
Clarification of Juices
Apple, lemon and pomegranate were purchased from a local
fruit market and stored at 4C until use. Each of the juices
was extracted from 100 g of respective fruits using a lab
mixer grinder; the extracted pulp was filtered in muslin
cloth to obtain raw juices (100 mL). The purified enzyme (5
and 10 U/mL) was mixed with the raw fruit juices (1%, v/v)
and incubated at 45C for 1 h, under stirred condition, using
a Genei magnetic stirrer (Bangalore Genei India Pvt. Ltd.).
The reaction was terminated by increasing the temperature
of the mixture to 90C for 5 min. The MnP-free and MnP-
treated clarified juices were centrifuged at 2,200 × g for
10 min and used for the physicochemical analyses including
phenolic content estimations, decolorization tests, clarifying
of juices inspections, etc. The total phenolic content in the
juice before and after enzyme treatment was determined by
the method of Swain and Hillis (1959). The absorbance was
recorded at 725 nm in a Beckman Coulter DU 50 spectro-
photometer using gallic acid as a standard. The content of
total polyphenolics in the juice was expressed as gallic acid
equivalents in mg/L of the samples. The phenolic content in
enzyme-free treatment (control) of fruit juices served as
100%. The clarity and color of the juice, before and after
treatment with enzyme, were studied by measuring the
absorbance at 650 and 420 nm, respectively.