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The capabilities of tyrosinase and peroxidase to activate tyrosine residues of wool fibres and to catalyze crosslink formation between peptides derived from a wool protein hydrolyzate were investigated. Peroxidases were able to catalyse oxidation of wool fibres corresponding to 35–40% of the tyrosine residues located on the wool surface or 2% of the tyrosine residues in the wool fibre. Similar fibre surface modification was detected with tyrosinase and a fungal peroxidase using x-ray photoelectron spectroscopy. Tyrosinase did not show detectable activation of fibres measured as oxygen consumption. Tyrosinase was, however, able to crosslink peptides of 3–10 kDa derived from enzymatically hydrolysed wool fibres. Surprisingly, no crosslinking was detected with peroxidase.

West Indian cherry (Malpighia glabra L.) and pineapple (Ananas comosus (L.) Meer)juice clarification by cross-flow UF, using polysulphone hollow fiber and ceramic tubular membranes with, respectively, nominal molecular weight cut off values of 100kDaltons and average pore diameters of 0.01mm, were studied. The influence of enzymatic treatment using enzyme concentrations of 20, 100 and 300mg/L, a time of 90min and a temperature of 40oC for depectinization was verified. The juices were then clarified in a laboratory scale filtration unit, with an effective filtration area of 0.12m2 for the polysulphone hollow fiber membrane and of 0.005m2 for the ceramic tubular membranes. The influence of enzymatic treatment on viscosity, turbidity and total pectin of the juice, before ultrafiltration, is reported. Membrane performance was evaluated in terms of flow rate and clarity of the permeate. The permeate flow rate of depectinized pineapple juice was higher (30 - 60%) for both membranes. Depectinized West Indian cherry juice presented a lower permeate flow rate for the polysulphone hollow fiber membrane. The increase in permeate flow rate, with the use of the 300mg/L and 100mg/L enzyme concentration was not significant, so it is economically advantageous to ultrafilter depectinized juice, treated with an enzyme concentration of 20mg/L.

West Indian cherry (Malpighia glabra L.) and pineapple (Ananas comosus (L.) Meer)juice clarification by cross-flow UF, using polysulphone hollow fiber and ceramic tubular membranes with, respectively, nominal molecular weight cut off values of 100kDaltons and average pore diameters of 0.01mm, were studied. The influence of enzymatic treatment using enzyme concentrations of 20, 100 and 300mg/L, a time of 90min and a temperature of 40ºC for depectinization was verified. The juices were then clarified in a laboratory scale filtration unit, with an effective filtration area of 0.12m² for the polysulphone hollow fiber membrane and of 0.005m² for the ceramic tubular membranes. The influence of enzymatic treatment on viscosity, turbidity and total pectin of the juice, before ultrafiltration, is reported. Membrane performance was evaluated in terms of flow rate and clarity of the permeate. The permeate flow rate of depectinized pineapple juice was higher (30 - 60%) for both membranes. Depectinized West Indian cherry juice presented a lower permeate flow rate for the polysulphone hollow fiber membrane. The increase in permeate flow rate, with the use of the 300mg/L and 100mg/L enzyme concentration was not significant, so it is economically advantageous to ultrafilter depectinized juice, treated with an enzyme concentration of 20mg/L. Foi estudada a clarificação através da ultrafiltração por flow rateo cruzado, dos sucos de acerola (Malpighia glabra L.) e Abacaxi (Ananas comosus (L.) Meer), usando membranas de polisulfona fibra oca e tubular cerâmica com peso molecular de corte de 100kDaltons e diâmetro médio de poro de 0,01mm, respectivamente. A influência do tratamento dos sucos, com concentrações de enzima de 20, 100 e 300mg/L, tempo de tratamento de 90min a temperatura de 40ºC, foi verificada, e então os mesmos foram clarificados numa unidade de ultrafiltração com uma área efetiva de 0,12m² para a membrana de polisulfona e de 0,005m² para membrana cerâmica. A influência do tratamento enzimático foi avaliada em termos da viscosidade, turbidez e pectina total do suco, antes da ultrafiltração. Os desempenhos das membranas foram avaliados em termos de flow rate permeado e claridade do permeado. O flow rate permeado do suco de abacaxi tratado foi mais alto (30 - 60%) para ambas as membranas do que para o suco natural. O suco de West Indian cherry despectinizado apresentou flow rate permeado menor para a membrana de polisulfona. O aumento de flow rate, observado com 300mg/L e 100mg/L de enzima não foi significante, concluindo-se que é vantajoso o tratamento com uma concentração de enzima de 20mg/L.

The effect of blanching, post-harvest refrigerated (4C) storage and enzyme treatment with poly-galacturonase on the microstructure of Spartan apple juice was examined by thin sectioning and negative staining transmission electron microscopy. Particles were categrized as granules (3-54 nm), spheres (20-368 nm) and aggregates (12-2519 nm). Enzyme treatment with polygalacturonase significantly decreased granule size (P < 0.01). Storage of apples significantly decreased both granule size (p < 0.01) and aggregate length (p < 0.05) and also resulted in a web-like aspect in the microscopic appearance of juice particulate. The web-like aspect of the particulate was removed either through enzyme treatment with polygalacturonase or by blanching. Blanching of puree significantly increased granule (p < 0.05) and sphere size (p < 0.01) while significantly decreasing aggregate length (p < 0.01). In addition, blanching stabilized suspended particulate by what appeared to be the formation of a protective colloid which prevented particle aggregation through electrostatic repulsion.