Manufacture and characterization of acid-coagulated fresh cheese made from casein concentrates obtained by acid diafiltration.

This study aimed to investigate the production of acid-coagulated fresh cheese by using slightly acid diafiltered (DF) microfiltered (MF) casein concentrates (8% protein). Three different acidifying agents were tested during DF: carbon dioxide, lactic acid, and citric acid. Fresh cheese was manufactured using acid-DF casein concentrates, or casein concentrates DF with just water, and compared with cheese manufactured using MF casein concentrates without DF. The fresh cheeses were characterized for composition, rheological, and sensorial properties. Acid-DF casein concentrates improved acidification kinetics during cheesemaking and reduced casein leakage to cheese whey, compared with cheese from regular MF casein concentrate. Among the rheological properties investigated in this study, the storage modulus of the fresh cheese was higher when DF of the casein concentrate was performed with nonacidified DF water or when DF water was acidified with citric acid. However, fresh cheese made from casein concentrate diafiltered with DF water acidified by citric acid was most liked in a sensory ranking test.

Minor acidification of diafiltration water using various acidification agents affects the composition and rennet coagulation properties of the resulting microfiltration casein concentrate.

Cheese made from microfiltration (MF) retentate may suffer from textural defects due to a high Ca concentration. The reduction of colloidal minerals by the acidification of milk before MF at pH below 6.0 has been well documented in the literature. This process, however, creates less valuable side streams to the MF process and induces changes in the casein micelles that negatively affect their coagulation properties. The objective of this study was to determine whether a minor reduction in pH by using different acidifiers in the diafiltration (DF) water could induce changes in composition and renneting properties of the MF retentate. A 2-stage filtration process was used, with the first designed to increase the casein concentration to 8% and the second to slightly reduce the casein concentrate by 0.1 pH unit by DF, without influencing the total protein concentration. Four acidifying agents were tested during DF: lactic acid, hydrochloric acid, citric acid, and carbon dioxide. Diafiltration with water was used as a reference. At the start of DF, the retentates of acid DF had a slightly reduced pH, with an average of 0.09, whereas the pH of the reference retentate increased by an average of 0.07 unit. The reference retentate regained its starting pH by the end of DF. The carbonated retentate gradually increased in pH during processing, whereas the pH of the lactic, hydrochloric, and citric acid retentates remained constant. The permeate from the lactic acid and carbonated treatments had a reduced whey protein content compared with the reference. The total P and inorganic phosphate were lowered in the retentate by using carbonation. The total amount of Mg and Na were lowered in the retentate by using citric acid. The ionic Ca content in the retentate increased with use of lactic or hydrochloric acid. The type of acidifier used reduced the rennet clotting time. Combined acidified diafiltration with a slight reduction affects the permeate composition and improves the retentate clotting time despite the minimal mineral modification.