Comparação entre leites estável e instável não ácido na produção de queijo Tipo Grana: Avaliações físico-química, sensorial e microbiológica durante a maturação

Abstract

Milk can become unstable due to a reduction in pH caused by lactose fermentation, thus being classified as acid milk. There are also cases where milk presents normal pH and acidity but remains unstable, characterizing it as non-acid unstable milk (LINA). LINA is rejected by dairies due to the alteration in the structure of casein micelles, which destabilize with heat, causing protein precipitation during thermal processing. In cheese production, coagulation is necessary, so lower milk stability may not affect the process. In the manufacture of hard cheeses, calcium chloride (CaCl2) is added to increase the soluble calcium content in milk, which aids in the formation of the cheese mass, and if not added, coagulation will be slow and incomplete. Thus, the objective of this study was to produce grana-type cheeses with LINA and stable milk, with and without the addition of CaCl2, to determine the influence of LINA on the physicochemical characteristics and whether. In the milk, the alcohol test (72, 74, and 76% (v/v)), titratable acidity, total bacterial count, somatic cell count, pH, thermal stability, total and ionic calcium, total proteins, % of fat and lactose, total dry extract, defatted dry extract, and electrical conductivity were carried out on the samples of LINA and stable milk (LE). In the cheeses, yield, physicochemical and microbiological characteristics, total calcium, ripening indices, color, texture, and sensory evaluation were determined. LINA showed lower protein content (3.32 g/100g) and lactose (4.90 g/100g) compared to LE (3.54 g/100g and 5.21 g/100g respectively) and higher fat content (4.32 g/100g), total calcium (222.5 mg%) and ionic (0.1283 g/L) when compared with stable milk (3.62 g/100g, 163.5 mg% and 0.0824 g/L respectively). The physicochemical characteristics were similar to LE, with the only difference being the electrical conductivity of the milk (5.61 mS in LE and 5.78 mS in LINA) due to the higher ionic calcium content present in this milk. LINA interfered with the characteristics of the cheeses, as well as the addition of CaCl2 in the formulation. The cheeses produced with LINA had lower pH values (5.19 with CaCl2 and 5.18 without CaCl2), higher acidity (0.98 with CaCl2 and 0.82 without CaCl2), and lower moisture content (28.52 with CaCl2 and 29.27 without CaCl2), when compared to the cheeses produced with LE. The microbiological characteristics of all the evaluated cheeses were within the standards required by legislation. LINA interfered with the texture profile of the cheeses, making them harder when produced with CaCl2 and less hard when produced without CaCl2. The sensory analysis showed that all the produced cheeses received a good overall impression (scores higher than 7.0), good acceptance (above 70%), and purchase intention from the evaluators (most evaluators would likely buy them). Thus, it is concluded that LINA can be used to produce hard cheeses of the Grana type, and its higher ionic calcium content can replace CaCl2 in the formulation.