Microbiological, sensory, and physicochemical quality of curd cheeses originating from direct sales

Curd cheeses are characteristic elements of the dairy assortment, mainly in Central and Eastern European countries, and constitute a numerous and diverse group of dairy products. The aim of the study was to assess the physicochemical, microbiological, and sensory quality of curd cheeses available in marketplaces in Lublin, where they were purchased through direct sales from producers.

The research material was household-produced curd cheese purchased 4 times (at 2-week intervals) from three producers. The physicochemical parameters (i.e., the total protein and fat content, active acidity, and titratable acidity) were determined in the cheeses. Microbiological assays were performed to evaluate the total number of bacteria (on milk agar), the number of yeasts and molds (on Sabouraud medium), and the number of coliform bacteria (on MacConkey medium). A general sensory evaluation was performed by a five-person panel, who assessed the appearance and color, texture, flavor, and aroma of the samples.

The cheeses exhibited significant differences in their protein and fat contents, but these values were within the allowable limits. Most of the evaluated cheeses had normal levels of active and titratable acidity; substantially lower titratable acidity and higher pH values were detected only in the samples from supplier A. The total number of bacteria in the curd cheese samples was high (3.2×10⁸ colony-forming units [cfu]×g^-1 cheese) and varied substantially (from 3.6×10⁷ to 8.6×10⁸ cfu×g^-1). The growth of Gram-negative bacterial colonies on MacConkey medium was observed in the samples from suppliers B and C (5.5×10³ and 1.7×10⁴ cfu×g^-1, respectively), which is an undesirable phenomenon. The number of colonies cultured on Sabouraud medium and identified as yeast-like microorganisms ranged from 1.8×10⁴ (product from supplier A) to 4.9×10⁵ cfu×g^-1 (cheese from supplier C). The scores in the sensory evaluation of the tested curd cheeses were low. The highest mean scores were achieved for appearance and color (4.25-4.45 points). Conversely, flavor and aroma received the lowest score (3.17 points). The highest scores for both the overall assessment and each parameter separately were awarded to the curd cheese produced by supplier A.

Our results suggest poor hygienic conditions during milk collection and processing, as well as during the distribution of these dairy products. Altogether, the purchase of products from direct sales may be associated with risks related to poor consumer health and food quality.