Optimizacija tehnološkog procesa proizvodnje napitaka od enzimski hidrolizovanog permeata mleka | Beverage processing optimization of enzyme hydrolyzed milk permeate

Valuation of the permeate as a by-product of the dairy industry is of great ecological, economic and technological importance. The aim of the PhD thesis is the development of the technological process of refining permeate, as a by-product obtained after ultrafiltration of milk during the production of feta cheese and fresh cheese. The possibility of enzymatic hydrolysis of the lactose in the permeate using the enzyme βgalactosidase isolated from Kluyveromyces lactis in a concentration of 0.1, 0.3 and 0.5 g / 100 g at a temperature of 20°, 30° and 40° C was examined. Changes in the content of lactose, D-galactose and D-glucose at intervals of 60 minutes were monitored. A special stage of the research included mathematical modeling and kinetics of lactose hydrolysis in the permeate under the influence of β-galactosidase and application of hydrolyzed permeate in the production of dairy products under the selected formulation. A technological process of producing a beverage on the basis of hydrolyzed permeate with the addition of fruit bases was suggested. Quality and durability parameters were determined for drinks during the 60 days of storage. Addition of the enzyme β-galactosidase at a concentration of 0.1 g /100 g for 60 minutes at a temperature of 40° C a 100 % degree of hydrolysis of lactose is achieved, present in the permeate. With a higher concentration of enzyme, 0.3 g /100 g or 0.5 g /100g, at the same temperature, the same effect can be achieved in 20 minutes. By examining the kinetics of lactose hydrolysis the first order kinetics was confirmed. Generally high coefficients of determination show good correspondence between the experimental results and the mathematical model of the first order reaction. Values range from 0.974 (at a temperature of 20° C) up to over 0.990 (at temperatures 30° C and 40° C) at a an enzyme concentration of 0.1g /100g. Beverages produced from hydrolyzed permeate are lactose-free and fat-free products. More than half of the total sugar content in all Dragana Ilić-Udovičić Doktorska disertacija VIII beverages consists of glucose: 50.16 % - forest fruit beverage, 50.42 % -beverage orange/carrot, 54.65 % beverage multivitamin and 55.13 % - beverage red fruit. The highest vitamin C content after production was in a beverage with the addition of fruit base multivitamin (0.3972 mg/100g), followed by forest fruit (0.2887 mg/100g) and orange/carrot (0.1999 mg/100g). Beverage samples with multivitamin and forest fruits showed the highest value of antioxidant activity after production. During the storage period there is a reduction of DPPH values. The smallest decrease was in the beverage with orange/carrot (decreased 17 %), and the biggest in the beverage with forest fruit (39 %). The content of polyphenols in analyzed samples ranges from 53.78 to 120.38 mg GAE/L depending on the type of beverage and added fruit base. Overall it can be concluded that the applied technological process gives beverages of stable physical and chemical content during the 60 days of storage, of high nutritional value and low energy.