Economic feasibility evaluation of microfiltration of milk prior to cheesemaking.
A nonlinear programming optimization model was used to evaluate the net revenues and potential profit-ability of microfiltration (MF) prior to cheesemaking in the 3-year period 1998 to 2000, using monthly milk price and composition data. The model identifies the optimal mix of milk resources and determines if MF cheesemaking produces a higher net revenue than conventional cheesemaking that uses NDM and condensed milk for fortification. This study demonstrates the potential of this model to evaluate new technologies in cheese manufacture and improve decision making in the cheese industry. The use of MF produced higher net revenues in 30 out of the 36 mo for both Cheddar and low-moisture, part-skim mozzarella, leading to an appreciable increase in net revenue (vs. conventional cheesemaking) for both cheeses. The benefit from MF in net revenue was greater when the cream price was high. The use of 3X MF yielded the same net revenue as 2X MF. An estimate of manufacturing costs of MF vs. conventional cheesemaking was also made. To this end, the yields of products were calculated by the optimization model, while the production cost of each product was estimated from data of two economic engineering studies and a MF cheesemaking trial. The manufacturing cost of MF Cheddar was slightly higher than the manufacturing cost of conventional Cheddar. However, the benefit in net revenue from the use of MF was estimated to be higher than the difference in manufacturing costs. Moreover, some advantages in the new coproducts of MF Cheddar could outweigh its higher manufacturing cost. The relationships between prices and recoveries of coproducts required to render MF profitable were identified.
Nanofiltration Concentration Effect on the Efficacy of Lactose Crystallization
Application of nanofiltration membranes to processing sweet whey and skim milk ultrafiltration permeate increased lactose crystal yield by about 10 and 8 %, respectively, at a concentration factor of 3.0. These increases were attributed to depletion of minerals, especially monovalent cations such as sodium and potassium, by the partial demineralization effect of the nanofiltration membrane. These membranes may be incorporated into current industrial processes for producing lactose from whey and milk permeates.
Factors Affecting Nonenzymatic Browning of Process Cheese
Abstract Variations in manufacturing procedures and the composition of stirred-curd Cheddar cheese were investigated for effects on nonenzymatic browning in process cheese. Using a nongalactose-fermenting Streptococcus thermophilus culture as an adjunct to mesophiic lactic starter culture resulted in increased galactose concentration in cheese and intensified browning of process cheese. The correlation between galactose content in stirred-curd cheese and brown color intensity in process cheese was very high (r=.929). Higher salt-in-moisture ratios of stirred curd cheese were related to more intense brown color in process cheese. The high salt-in-moisture ratio probably reduced the catabolic activity of the lactic starter and resulted in more residual lactose and galactose in the cheese. Increasing available amino groups in stirred curd cheese by adding casein hydrolysate proved inconclusive. Faster cooling of process cheese from 80 to 37.7°C reduced intensity of brown color. Process cheese cooled very rapidly did not develop any brown color, regardless of sugar and salt contents. Browning may be controlled by regulating salt and by using strains of Streptococcus thermophilus that ferment galactose.