CONTROL of ENZYMATIC BROWNING IN RAW FRUIT JUICE BY FILTRATION and CENTRIFUGATION

Abstract

Filtration and centrijkgation w r e investigated as means ofpreventing enzyntatic broming in minimally processed fiuit juices. Ihe cqacity of raw apple, grape and pear juices to undergo browning was associated with particulate fractions that could be removed by jiltration with Bentonite andor diatomaceous earth, microjiltration or ultrafiltration, depending on the commodity and cultivar. C e s trifugation prevented browing in pear juice and in Granny Sznith, Golden Delicious, and Red Delicious but not Mchtosh apple juice, provided that fim was excluded and the relative centrifigal firce was suflcient. A method fir the preparation of nonbrowning, cloudy juices by recombination ofjuice supernatant or ultrajiltration permeate with particulates, heat-treated to inactivate polphenol oxidase, was investigated. 'Mention of brand or firm names does not constitute M endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned. 3end correspondence to: G. M. Sapers, Eastern Regional Research Center, ARS, U.S. Department of Agriculture, 600 E. Mermaid Lane, Philadelphia, PA 19118.

Chitosan Enhances Control of Enzymatic Browning in Apple and Pear Juice by Filtration

“…Chitosan treatments were effective in controlling enzymatic browning in pear juice, which, like McIntosh apple juice, also had not responded to filtration with CAFA (Sapers, 1991). A treatment level of 400 ppm was required with Anjou juice, irrespective of chitosan source (data for Protan Low Viscosity, Protan Extra High Viscosity and Sigma chitosans not shown).…”

“…AS REPORTED previously (Sapers, 1991), McIntosh apple juice was subject to rapid browning, even if partially clarified by addition of CAFA and filtration through Whatman No. 541 paper (Table 1).…”

“…RAW JUICE samples (300-500 mL represented 4-6 fruits) were prepared from ripe Granny Smith, Golden Delicious and McIntosh apples and Anjou, Bartlett and Bose pears, as described previously (Sapers, 1991). Ascorbic acid (500 ppm for Granny Smith and 1100 ppm for the other cultivars) and 0.1% Sigma Antifoam A (Sigma Chemical Co., St. Louis) were added during juicing to control browning during the application of chitosan treatments.…”

“…Filtration treatments (other than micro-or ultrafiltration) were ineffective unless preceded by addition of Bentonitem and/or Celitem, a diatomaceous earth. Filtration with Celite Analytical Filter Aid (CAFA) prevented browning of juice of Granny Smith, Red Delicious and Golden Delicious apples, but both filter aids were required to control browning in the juice of McIntosh apples and Bartlett and Bose pears (Sapers, 1991). Chitosans, biopolymers derived from shellfish chitin, have been proposed as "fining" agents for apple juice (Soto-Peralta et al, 1989;Boguslawski et al, 1990) and as coagulants for suspended solids in vegetable (Bough, 1975), seafood (No and Meyers, 1989), and other processing wastes (Knorr, 1984).…”

Fruit Manufacturing

“…While ascorbic acid-6-fatty acid esters showed Pierpoint (1966) antibrowning activity in juice, ascorbic acid-2-phosphate (AAP) and -triphosphate was effective for cut fruit surfaces. Sapers (1991) infiltrated ascorbic acid-2-phosphate (AAP) and ascorbic acid into apple tissue to control browning. Cinnamate and benzoate inhibited browning in juice, but induced browning when applied to cut surfaces.…”