Abstract
In this work, the effects of different combinations of lactic acid bacteria (LAB) on the growth of coagulase-positive staphylococci (CPS) and Escherichia coli were evaluated during ripening of 23 curd cheeses, and their subsequent behavior during the manufacture and storage of pasta-filata cheeses was characterized. Three groups of cheeses were prepared in total: first, control cheeses from raw milk without LAB addition; further pasteurized milk cheeses with LAB, CPS and E. coli intentional inoculation; and finally, raw milk cheeses with LAB added. The aim was to compare the effect of LAB from starter culture, and also in combination with native LAB, and to evaluate the LAB effect as a group, and further to suggest the culture with the best inhibitory potential. Based on the results, counts of CPS increased over 24 h in control curd cheese by 1.76 ± 0.56 log CFU/g. On the other hand, in raw milk cheeses with the addition of starter culture, the increase in CPS counts by 0.76 ± 0.87 log CFU/g was noticed. Counts of E. coli increased during the first 24 h of curd manufacture by 3.56 ± 0.41 log CFU/g in cheeses without LAB addition. Contrary to this, using of LAB cultures resulted in an increase in E. coli counts by only 1.40 ± 1.07 log CFU/g. After steaming at 63.6 ± 1.9°C for 7.2 ± 2.1 min (temperature of heated acidified curd was 54.9 ± 1.7°C), CPS decreased by 0.58 ± 1.12 log CFU/g, and E. coli decreased by 1.23 ± 0.97 log CFU/g in all cheeses, regardless of LAB addition. Finally, during storage of cheeses at 6 ± 0.5°C for 28 days, the levels of E. coli in control cheeses and in raw milk LAB-enriched cheeses reached levels of 2.07 ± 2.28 log CFU/g and 1.20 ± 0.85 log CFU/g, respectively. In addition, the counts of CPS at the end of storage met the criteria of EU Commission Regulation (EC) No. 1441/2007 (2007) (less than 4 log CFU/g) in all manufactured cheeses with added LAB culture, while in the control raw milk cheeses, a level of 3.80 ± 1.22 log CFU/g was observed. Regarding the culture used, the best microbiological inhibitory effect in 28-day-old cheeses was reached by the combination of Fresco culture with Lacticaseibacillus rhamnosus GG, and the best sensory properties were judged to be those for cheeses manufactured with Culture A. A moderate negative effect of storage on overall sensory acceptance was noted, according to the final evaluation of overall acceptability of pasta-filata cheeses. The most satisfactory overall acceptability after 28 days of storage at 6°C was reached for cheese with the addition of culture A.
Highlights
The pasta-filata cheeses include a wide range of cheeses originating primarily in the northern Mediterranean region: e.g., Italy, Greece, the Balkans, and Turkey
To study the effect of lactic acid bacteria (LAB) presence on microbiological and sensory quality of pasta-filata cheeses, we prepared 23 cheeses divided into 3 groups as specified in Table 1: 5 cheeses from raw milk without any added LAB culture, 8 cheeses made from pasteurized milk with intentional inoculation of S. aureus and/or E. coli and LAB culture and 10 cheeses from raw milk with addition of different LAB cultures
Traditional raw milk cheeses are of great importance to maintain national heritage and tend to display greater variability, and strong and unique sensory properties compared with cheeses from pasteurized milk (Pappa et al, 2019); the usage of raw milk carries a potential health risk (Verraes et al, 2015)
Summary
The pasta-filata cheeses include a wide range of cheeses originating primarily in the northern Mediterranean region: e.g., Italy, Greece, the Balkans, and Turkey They have become global favorites as ingredients in a variety of foods, especially pizza (Albenzio et al, 2013). In Slovakia, the manufacture of pasta-filata type cheeses: e.g., Parenica, Oštiepok, Zázrivské vojky, Zázrivský korbácik, and Oravský korbácik, is of great importance to preserve national gastronomic heritage, and they are designated for the Protections of Geographical Indications (PGI) (2005) (EC No: SK/PGI/005/0485/19.07.2005). They are produced from lump cheese, which is manufactured from raw milk in Slovakian upland cottages immediately after milking. The lumps are steamed at 60–70◦C in hot water for 5–10 min, cooled (usually in salty water) and shaped (Licitra et al, 2018)
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