Evolution of microbial counts and chemical and physico-chemical parameters in high-moisture Mozzarella cheese during refrigerated storage

Innovative Covering Liquids Stabilising Water-Fat Leachate from Fresh Mozzarella Cheese Used as Pizza Topping

This study analyses the possibility of changing the composition of the covering liquid in which mozzarella cheese is stored. The characterisation of mozzarella cheese consumed fresh and during later culinary use as a pizza topping was carried out. Mozzarella cheese from cow's milk and reconstituted sheep's milk were used for this study. The cheese was stored in whey-based covering liquid to which single or double amounts of lactose and/or citric acid (w/w) were added. The results obtained during laboratory analysis showed that the addition of lactose and/or citric acid to the covering liquid significantly impacted the mass of the cheese and the changes that can occur during later culinary use. The observed changes in the cheese during storage in the covering liquid were confirmed by the characteristics of the liquid itself. The smallest mass changes were related to cheeses stored in a covering liquid with double the amount of lactose and a single amount of citric acid. This cheese also displayed positive changes in all assessed descriptors (texture, melt, and colour). The amount of leachate from the cheese was small and occurred relatively late after unpacking and quartering. Based on the results of the study, changes made to the composition of the covering liquids can positively affect the characteristics of mozzarella cheese. Additionally, this data allows for the creation of specialised mozzarella cheeses that can pique the consumer's interest.

Mango (Mangifera indica L.) young leaf extract as brine additive to improve the functional properties of mozzarella cheese

Mango (Mangifera indica L.) has been an important plant in traditional medicine for over 4000 years, probably because of its remarkable antioxidant activity. In this study, an aqueous extract from mango red leaves (M-RLE) was evaluated for its polyphenol profile and antioxidant activity. The extract was used as brine replacement (at 5%, 10% and 20% v/v) in fresh mozzarella cheese for improving its functional properties. During storage (12 d at 4 ± °C), compositional analysis performed on mozzarella has shown a progressive increase of iriflophenone 3-C-glucoside and mangiferin, the compounds most present in the extract, with a noticeable preference for the benzophenone. At the same time, the antioxidant activity of mozzarella peaked at 12 d of storage, suggesting a binding action of that matrix for the M-RLE bioactive compounds. Moreover, the use of the M-RLE has not negatively influenced the Lactobacillus spp. population of mozzarella, even at the highest concentration.

Application of antimicrobial coating based on carboxymethyl cellulose and natamycin in active packaging of cheese

The effects of carboxymethyl cellulose (CMC)-natamycin (N; 0.05 and 0.5%) coating on the quality of high-moisture mozzarella cheese (HMMC) were examined. The cheeses were immersed in the coating solutions and then kept at 7 °C for 8 days and microbial specifications (i.e., total mesophilic count, total psychrophilic count, lactic acid bacteria, and yeast-mold), pH, weight loss, and sensory properties were examined. The results of the agar spot diffusion assay represented inhibitory effects of CMC-N coating solution on Aspergillus flavus, A. fumigatus, A. niger, Penicillium citrinum, and Candida albicans. In HMMC, the natamycin-free CMC coating caused a significant decrease (p < 0.05) in all microbial groups, while the addition of natamycin to the coating only reduced the count of mold and yeast. As a result, the coating with natamycin at 0.05 and 0.5% represented a 0.6 and 0.9 log cycle reduction in yeast-mold populations, respectively. Based on the total mesophilic count, the control samples reached the 7 log CFU/g on day 4, indicating a 4-day shelf life of HMMC, while in HMMC coated with and without natamycin this limit was achieved on the 8th day of storage, which indicates that the coatings have doubled the HMMC shelf life.

Development of "Quadrello di Ovino", a Novel Fresh Ewe's Cheese

This work was performed to produce a new soft ewe's milk cheese, namely "Quadrello di ovino" (QdO) cheese, to enlarge ewe's dairy product portfolio of South Italy, barely limited to Pecorino cheese typology. Cheese making was performed applying the technology for "Crescenza" cheese typology with some modifications. In particular, pasteurized ewes' milk was inoculated with two commercial starter formulations (SF1 and SF2) of Streptococcus thermophilus to obtain two different productions (QdO-P1 and QdO-P2, respectively). Plate counts demonstrated the ability of both starter formulations to drive the fermentation process, since S. thermophilus counts reached 109 CFU/g in both productions. Generally, the two starter formulations did not affect the chemical composition of QdO cheeses that contained, on average, 64.08% dry matter of which approximately 54.99% were fats and 36.39% proteins. Among chemical parameters, significant differences were registered for secondary lipid oxidation state (significantly lower for QdO-P2), fatty acids and volatile organic compounds (VOCs). However, the differences registered among cheese VOCs from were not perceived by the panelists who recognized both cheese productions highly similar, although QdO-P2 cheeses were mostly appreciated by the judges. This study allowed to produce a novel fresh ovine cheese with specific chemical and sensorial characteristics well appreciated by consumers.

Effect of thermoresistant protease of Pseudomonas fluorescens on rennet coagulation properties and proteolysis of milk

This study aimed to investigate the effect of different activity levels of a thermoresistant protease, produced by Pseudomonas fluorescens (ATCC 17556), on the cheesemaking properties of milk and proteolysis levels. Sterilized reconstituted skim milk powder was inoculated with the bacteria, and after incubation, centrifuged to obtain a supernatant-containing protease. Raw milk was collected and inoculated to obtain a protease activity of 0.15, 0.60, and 1.5 U/L of milk (treatments P1, P4, and P10, respectively). One sample was not inoculated (control) and noninoculated supernatant was added to a fifth sample to be used as a negative control. Samples were stored at 4°C for 72 h. After 0, 48, and 72 h, the rennet coagulation properties and proteolysis levels were assessed. The protease produced was thermoresistant, as no significant differences were observed in the activity in the pasteurized (72°C for 15 s) and nonpasteurized supernatants. The chromatograms and electrophoretograms indicated that the protease preferably hydrolyzed κ-casein and β-casein, and levels of proteolysis increased with added protease activity over storage time. The hydrolysis of α_S-caseins and major whey proteins increased considerably in P10 milk samples. At 0 h, the increase in the level of protease activity decreased the rennet coagulation time (RCT, min) of the samples, possibly due to synergistic proteolysis of κ-casein into para-κ-casein. However, over prolonged storage, hydrolysis of β-casein and α_S-casein increased in P4 and P10 samples. The RCT of P4 samples increased over time and the coagulum became softer, whereas P10 samples did not coagulate after 48 h of storage. In contrast, the RCT of P1 samples decreased over time and a firmer coagulum was obtained, possibly due to a lower rate of hydrolysis of β-casein and α_S-casein. Increased levels of protease could result in further hydrolysis of caseins, affecting the processability of milk over storage time.