A NOVEL ENZYMATIC MACERATION TREATMENT TO ENHANCE THE PHENOLIC CONTENT OF APPLE JUICE
Special Symposium - Innovations in Food Technology (LMC Congress)
Innovations in Food Technology - Poster Session (Food - P2)
Keywords: Apple juice, Phenol compounds, Proteases, Effective diffusivity, Mass transfer.
In the industrial preparation of apple juice, pectinases are added in order to make it easier to extract the juice from the pulp and increase the juice yield during the pressing step. Transfer of phenolic compounds from apple mash to the juice is restrained by the complex polysaccharide matrix forming the apple cell walls, including pectins, cellulose, and protein. The use of enzymes able to catalyze the degradation of these structures could help increase the release of phenols entangled in the cell wall or those contained in the cell vacuoles. To assess the latter hypothesis, a 23 experimental design with 4 repetitions in the central point has been performed in order to study the effects on the phenol content of the juice of different dosages (from 0 to 0.2% ml/100g apple mash) of three commercial enzyme preparations: the cellulase Celluclast 1.5L and the two proteases Enzeco and Sumizyme AL, all of them from Aspergillus niger strains. A dosage of 0.05% Enzyme/apple mash w/w of Pectinex Smash was added to the apple mash over the enzymatic maceration in all the experiments, taking it as a control. Evolution of viscosity was followed during the enzymatic maceration as a measurement of the sugar degradation. In the experiments including cellulases, viscosity decrease was ~20% higher than in the no-cellulase ones. Proteases did not seem to have a particular effect on sugar degradation. Regardless of the enzymatic treatment applied, no variations were detected in the apple juice yields. No differences in the content of phenols of extracts were observed after 20 min of enzymatic treatment. At this time, the lowest level corresponded to the control and the one with just Celluclast 1.5L, whose phenolic content was 144 mg eq gallic acid/l. The highest level corresponded to the experiments in which just Sumizyme AP or Sumizyme AP + Enzeco were employed, with a phenol increase of 25% compared to the control
An apple juice sample treated with just the pectinase (control) and another one to which Sumizyme AP was added during the maceration were subjected to HPLC analysis. The chromatograms bore out the results previously obtained by Folin-Ciocalteau phenol analysis. The same type of phenolic compounds were obtained by both treatments, but in a higher amount when Sumizyme AP was employed. Two main groups of phenolics could be detected: 1) Phenolic acids (chlorogenic acid) and flavanols (epicatechin, procyanidins). The presence of different kinds of phenolic compounds in the juice with time was studied by comparing the values of the effective diffusivities related to each kind of phenolic compound and results will be presented. From all these data it was possible to conclude that protease treatment of apple mash induced significantly increased release of phenols into apple juice.
Presented Thursday 20, 13:30 to 14:40, in session Innovations in Food Technology - Poster Session (Food - P2).
