Microbiological and biochemical changes in herby cheese during ripening

Abstract

The aim of this study was to determine and compare the microbiological, biochemical and sensory characteristics of herby cheese made with two different methods. In the first method (M1), milk and herbs were pasteurized at 65°C for 30 min, and Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris were added as starter culture at an inoculum ratio of 1.5%. In the second method (M2), the conventional cheesemaking was applied. Microbiological and biochemical changes were monitored throughout the ripening period of 90 days. Samples were taken from cheeses on days 1, 15, 30, 60, and 90. At the end of ripening, sensory characteristics of cheeses manufactured with both methods were evaluated. The obtained results suggested that most changes in pH, titratable acidity, and dry matter contents of cheese varieties were not found to differ statistically significant, but the difference in salt content was significant (P < 0.01). Total aerobic count, lactic acid bacteria, Staphylococcus aureus, coliforms, moulds, yeasts, proteolytic and lipolytic microorganism counts were lower in M1 cheese samples than those of M2 cheese samples (P < 0.01). The numbers of psychrotrophic microorganism in both cheese types were not found to differ significantly. Moreover, the results suggested that there were significant differences (P < 0.01) in the degrees of proteolysis and lipolysis of the cheese varieties. High proteolysis and lipolysis rates were monitored in the traditional cheese samples. However, there were no significant differences between the sensory characteristics of cheese samples.

Cheeses of Turkey: 3. Varieties containing herbs or spices

“…The use of raw milk in the manufacture of Otlu cheese enhanced lipolysis, due probably to the action of indigenous milk lipase [6]. The ADV value increased with the age of the cheese and the level of herbs added (Fig.…”

“…Total mean microbial counts in Otlu cheese are as high as 7.1 to 9.0 log cfu·g −1 [8,22,27] and increase with age [6,43,47]. The number of lactic acid bacteria increased during the first 30 d of ripening, then decreased to 90 d [6].…”

“…However, increasing the level of herbs caused some sensory problems in the cheese, and the best sensory scores were obtained for the cheese with 1% herb [41,45]. Higher levels of soluble nitrogen were found in the cheeses made from raw milk than those from pasteurized milk [6,48]. Tuncturk and Coskun [47] reported that proteolysis indices for Otlu cheese were higher in dry-salted cheeses than in their brined counterparts probably due to migration of some nitrogenous compounds into brine.…”

“…The number of lactic acid bacteria increased during the first 30 d of ripening, then decreased to 90 d [6]. The low pH of the cheese favours the growth of nonstarter lactic acid bacteria (NSLAB).…”

“…Yeasts and moulds are present at high numbers in Otlu cheese, e.g., 7.3 [22] or 5.2 [27] log cfu·g −1 . The numbers of yeasts and moulds decreased during ripening from 5.3 to 2.3 log cfu·g −1 [37] and 3.4 to 0 log cfu·g −1 [50]; however, some fluctuations in the growth of these organisms occur during ripening [6,47]. Counts of coliform microorganisms are high, particularly in raw milk cheeses, at the beginning of ripening, but their numbers decrease with age [6,47,50].…”