Méthode de Détection des Laits Susceptibles de Produire des Fromages à Saveur Fruitée

A fruity flavour note is traditionally regarded as a defect in cheese varieties such as Cheddar (Bills et al. 1965; McGugan et al. 1975; Horwood et al. 1987). However, fruitiness is an attribute of other cheese varieties such as Parmesan and Parmigiano Reggiano (Dumont et al. 1974; Meinhart & Schreier, 1986). It is well accepted that esters such as ethyl butanoate and ethyl hexanoate cause the fruity flavour described as apple-like or pineapple-like in raw milk and cheeses (Bills et al. 1965; Engels et al. 1997; Friedrich & Acree, 1998). The development of fruity flavour is often attributed to the esterification of free fatty acids and ethanol by esterases from lactic acid bacteria and psychrotrophic pseudomonads (Hosono et al. 1974; Morgan, 1976).

The Flavor, Volatile Acidity, and Soluble Protein of Cheddar and other Cheese

Raw milk cheeses

Simplification of a complex microbial antilisterial consortium to evaluate the contribution of its flora in uncooked pressed cheese

In this study, a comprehensive and comparative analysis was conducted on Italian Asiago-PDO cheese obtained from two different dairies named Dairy I and Dairy II using industrial and natural fermented milk, respectively. The analysis encompassed the evaluation of chemical composition, the succession of the microbiota during manufacture and ripening, and proteolysis mainly focusing on free individual amino acid (FAA) profiles. A metagenomic approach was used to investigate the cheese microbiome functionality. Differences in gross chemical composition were more evident during ripening, with Dairy II showing higher variability within batches. The microbiota varied significantly between the two dairies and ripening stages. The choice of starter culture shaped the microbiota during production and affected the microbial diversity of non-starter lactic acid bacteria (NSLAB) originated from the raw milk during ripening. Peptide chromatographic profiles and FAA concentrations increased as ripening progressed, with Dairy I showing higher production of FAA. Functional analysis of the metagenomes linked species to specific amino acid metabolism/catabolism pathways. The amino acid metabolism pathways, particularly those related to aromatic amino acids, lysine, and branched-chain amino acids, were affected by the presence of specific NSLAB species, which differed between the two dairies. The results obtained in this study reveal the impact of starter culture on peculiar cheese microbiota assemblies, which selectively targets amino acid pathways, providing insights into the potential flavor and aroma characteristics of Asiago-PDO cheese.

PurposeThe objective of this study is to evaluate the quality of Coalho cheese produced using two different strains of Lactococcus spp. that were isolated from artisanal Coalho cheese in Bahia, Brazil.Design/methodology/approachThree different batches of cheeses were produced using lactic acid Lactococcus spp. strains named “LA‐02”, “RE‐02” and “Blend” (LA‐02 plus RE‐02). To study the quality of these products the paper uses quantitative descriptive analysis (QDA), a test of acceptability and an analysis of physical‐chemical parameters.FindingsFor the flavor attribute, the highest acceptabilities were for LA‐02 (7.38) and Blend (6.92). The panelists found that 13 attributes were important to describe Coalho cheese. The Blend cheese was characterized by its yellow color, hardness, consistency, chewiness, typical Coalho cheese aroma and flavor. The LA‐02 cheese was characterized by its acid flavor, homogeneity and softness. All the samples analyzed showed values of moisture and fat that were in line with Brazilian legislation.Practical implicationsCoalho cheese is a typical Brazilian artisanal cheese that is normally produced with raw milk, even though legislation does not allow this. Pasteurization of the milk used to produce cheeses guarantees the microbiological safety of the product and, in this case, the cheese needs the addition of lactic acid bacteria in order to improve the sensorial quality and to give typical characteristics.Originality/valueCoalho cheese, as produced in the artisanal form, is widely appreciated for its sensorial characteristics. The Coalho cheese proposed in this research retains the typical sensory characteristics by using different strains of Lactococcus spp. that were isolated from artisanal Coalho cheese but according to the specification of good manufacturing practices (GMP).

The contamination of bulk samples of cow’s raw milk (<I>n</I> = 491) by psychrotrophic lipolytic bacteria (PLiBC), total count of psychrotrophic bacteria (PBC) and mesophilic bacteria (TBC) was monitored for two years on eight dairy farms and the correlations among these groups of bacteria were analysed. An increase in TBC, PBC and PLiBC and in the values of free fatty acids (FFA) was tested experimentally in three milk samples in relation to time (analyses were done in 24-hour intervals until 96 hours) and storage temperature of milk samples (4; 6.5 and 10°C). Bacterial contamination of milk was determined by culture methods in accordance with IDF standards, the values of FFA were determined by an extraction-titration method. These mean values were determined in the set of samples (<I>n</I> = 491): PLiBC 659 CFU/ml, PBC 2 932 CFU/ml and TBC 18 932 CFU/ml. A high correlation was proved between values of PBC and PLiBC (<I>r</I> = 0.87; <I>P</I> < 0.001) while the correlation between TBC and PBC (<I>r</I> = 0.65; <I>P</I> < 0.001) and between PLiBC and TBC (<I>r</I> = 0.59; <I>P</I> < 0.001) was on a medium level. The proportional index <I>p<sub>I</sub></I> for PLiBC/PBC was 0.20, for PLiBC/TBC 0.03 and for PBC/TBC 0.16. In seasonal dynamics a statistically significant difference (<I>P</I> < 0.001; <I>P</I> < 0.05) between the increased values of TBC in the summer season was proved compared to the winter and spring season. The differences in the seasonal variation of PBC and PLiBC values were not significant. Experimental investigation of an increase in the values of tested parameters showed that at temperatures of milk sample storage 4 and 6.5°C TBC did not exceed the permissible hygienic value (100 000 CFU/ml) even after 96 hours while at 10°C it amounted to 90 000 CFU/ml after 48 hours and the limit for TBC was exceeded several times after 96 hours. PBC, which is not inhibited by cold storage to such a large extent, did not exceed the hygienic limit value for PBC (50 000 CFU/ml) even after 96 hours when milk samples were stored at 4°C, but at 6.5°C after 72 hours and at 10°C already after 48 hours the values 6 and 20 times higher, respectively, than the hygienic limit were recorded. A similar trend was observed in PLiBC, which exceeded the hazardous limit (43 000 CFU/ml) at 6.5°C after 96 hours and at 10°C already after 48 hours whereas at 4°C the limit value was not exceeded even after 96 hours. The content of FFA also increased in relation to the storage time and temperature of milk samples but in comparison with the increase in the tested groups of microorganisms the increase in FFA showed a higher correlation with storage time compared to storage temperature. A medium correlation was calculated between PLiBC and/or PBC and FFA content (<I>r</I> = 0.52; <I>r</I> = 0.57; <I>P</I> < 0.001).

Mexican Chihuahua Cheese: Sensory Profiles of Young Cheese

Simultaneous determination of aflatoxin M1, ochratoxin A, zearalenone and α-zearalenol in milk by UHPLC–MS/MS

Bioconservation of artisanal raw goat milk cheese produced with lactic acid bacteria of the genus Lacticaseibacillus spp.

Changes in the volatile profile of a raw goat milk cheese treated by hydrostatic high pressure at different stages of maturation

Artisanal and experimental Pecorino Siciliano cheese: Microbial dynamics during manufacture assessed by culturing and PCR–DGGE analyses

Listeria monocytogenes is a Gram positive facultative intracellular organism and food borne infective agent that can effect severely to humans and animals. Listeria monocytogenes primarily causes infectious disease such as meningitis, septicemia, and meningoencephalitis that leads to 20 to 25% of death rate in humans. Ingestion of L. monocytogenes contaminated food such as meat, eggs, dairy products, fruits and vegetables leads to serious infectious disease Listeriosis. Most common sources of L. monocytogenes transmission are raw milk, dairy products and dairy plant contaminated by sick farm animals and rarely from the contaminated environment. Bacteriophages specific for Listeria monocytogenes may have a potential role in elimination of sources of contamination. This study was designed to isolate L. monocytogenes specific bacteriophage for lysing the isolate of L. monocytogenes from raw milk using fraser broth. Gram staining, hemolysis test on sheep blood, catalase test and sugar fermentation test were used to confirm colonies grown on plate. The colonies were further streaked on trypticase soy yeast extract and showed white shiny glass like appearance. Isolation and confirmation of bacteriophages was performed by plaque assay method. Abundant of phages are analyzed in sewage water which are vulnerable and extremely flexible host for the presence of Listeria phages. The overall results showed that out of 500 samples of raw milk from five different dairy farms 100 each, 80%, 60%, 32%, 54%, 85% were positive from dairy farm 1, 2, 3, 4, 5 respectively. Five sewage samples were subjected to plaque assay and lysate was prepared. The plaques formed by phages appeared in the form of spherical zone which varies in size and showed lysis of L. monocytogenes. The number of PFU from phage lysate was ranging from 1×103 to 1×106 and estimate plaque size was 0.2±0.5. These results demonstrate application of phages in food industry. Phages can be used individually or in combination as well for the treatment of bacterial infections by targeting cell lysis due to its lytic potential.

Background: Foodborne infections like Listeriosis cover several disorders and are a worldwide public health emergency. Listeria monocytogenes has been isolated from various foodstuffs, including milk and fishes. MALDI-TOF mass spectrometry technique is known for its rapid and accurate identification of bacterial organisms. Methods: In the current research, a total of 360 samples comprising raw milk (130), milk products (125) and freshwater fishes (105) were screened for the detection of pathogenic Listeria species by using the USDA method. The recovered Listeria isolates were characterized using conventional set of biochemical analysis along with sugar fermentation tests and further confirmed by MALDI-TOF MS. The virulent nature of pathogenic Listeria isolates was also assessed by in vitro tests like hemolysis on blood agar, CAMP and PI-PLC assay. Result: In current study, on screening 360 animal origin food samples, three isolates were recovered from raw milk samples and identified as Listeria monocytogenes indicating an overall prevalence of Listeria monocytogenes to the tune of 0.83%. Excellent correlation was observed with identification of Listeria species using conventional phenotypic tests and advanced molecular tool Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) technique. The results depict dependability of advanced technique for rapid and reliable identification of Listeria species.

Characterisation of Egyptian Ras cheese. 2. Flavour formation