Influence of Acidification Method on Composition, Texture, Psychrotrophs, and Lactic Acid Bacteria in Minas Frescal Cheese

Abstract

The suitability of carbon dioxide (CO2) addition to milk for the manufacture of rennet-coagulated Minas Frescal cheeses was evaluated. The objectives of this work were to evaluate the influence of milk carbonation on Minas Frescal textural, microbiological, and physicochemical parameters as a method of acidification. A control (pH 6.8), two CO2-treated, and two lactic acid-treated (pH 6.4 and 6.0) cheeses were produced and evaluated. Milk preservation promoted the multiplication of lactic acid bacteria in cheeses produced by both processes. The use of lower pH milk showed higher effectiveness over psychrotrophs, proteolytic, and lipolytic psychrotroph counts on the first days of storage, extending the lag phase. From 12 days on this pH, inhibition effect over psychrotrophs was severely reduced, especially in CO2-treated cheeses, where a difference of 1.52 log (day 4) was reduced to 0.23 log (day 12) when comparing treatments of pH 6.0 to 6.4. Cheeses produced with CO2 showed higher hardness, regardless of pH. Moisture and pH decreased with time due to syneresis and the production of lactic acid, respectively. Significant differences were found in fat, protein, and ash contents. Cheeses treated with CO2 showed higher protein/fat proportions. According to the results of this work, CO2-treated thermized milk can be satisfactorily used in the manufacture of Minas Frescal cheese, showing psychrotroph inhibition equivalent to that with added lactic acid and improved hardness.