M.E. Tornadijo

Characterization of Prato cheese, a Brazilian semi-hard cow variety: evolution of physico-chemical parameters and mineral composition during ripening

Abstract The evolution followed by the overall chemical composition, physico-chemical parameters and the main mineral and trace elements during the ripening of 18 batches of artisanal Prato cheese was studied. This cheese is characterised for its high total solids values (69.15±3.79 g/100 g), as well as low NaCl values (1.03±0.56 g/100 g) which were lower than those described for the majority of other cows milk cheeses studied. Its lactose content disappeared after the first month of ripening, without observing any significant variations in pH values during ripening. The Ca, P, Zn and Mn contents showed a significant decrease ( p

Survival of Enterobacteriaceae during processing of Chorizo de cebolla, a Spanish fermented sausage

Chorizo de cebolla is a popular semi-dry fermented sausage from Galicia (NW of Spain). The survival of Enterobacteriaceae was investigated in three batches of C. de cebolla (one of them hand made and the other two manufactured industrially). The maximum count of Enterobacteriaceae was obtained in each lot after 2 days of the raw sausage mix being stuffed and from then on it started to decrease until it disappeared in the fourth week of ripening in one of the batches manufactured industrially and after 6 weeks in the other. In the artisanal sausages the counts practically decreased exponentially until the third week of ripening, increasing in the following week before again decreasing until the end of ripening, though they never disappeared. Escherichia coli, Serratia odorifera and Enterobacter intermedius were the only species isolated during the curing process of the hand made sausages, E. coli being the dominant species. In the industrial ones a higher number of species were isolated, with the predominance of E. coli and Hafnia alvei.

Characterization and biochemical changes during the ripening of a Spanish craft goat's milk cheese (Armada variety)

The gross and mineral composition, and some physico-chemical parameters were determined in 15 batches of Armada goats milk cheese (a Spanish craft variety), as well as in the milk used for its manufacture. Some biochemical changes during the ripening process have been also investigated. The milk used in the elaboration of Armada cheese had higher lactose, fat, protein and ash contents than previously reported by other authors, whilst iron content was lower than recent results for goats milk from other countries. Armada cheese showed a high total solids content and a low NaCl and ash content. Water activity (Aw) values decreased progressively during ripening, reaching very low final values (0.895 on average). Lactose disappeared almost completely within the first 7 days of ripening, when the cheese had the lowest pH values (about 4.50). l-Lactic acid dominated in the curd, but during the ripening process both isomers (d- and l-) tended to balance. Variations in mineral content during ripening were only found for magnesium, calcium, phosphorus and zinc: they showed a significant reduction in the first days of ripening coincidental with a decrease in pH values.

Proteolytic and lipolytic changes during the ripening of a Spanish craft goat cheese (Armada variety)

The proteolytic ad lipolytic changes during the ripening process were investigated in four batches of Armad goats milk cheese (an artisanal variety produced in the North of Spain), by determining the classical nitrogen fractions, caseins and their degradation products, free amino acids, as well as the acidity of the fat, thiobarbituric aicd number and free fatty acids

Microbiological and physico-chemical changes in Genestoso cheese, a Spanish acid curd variety, throughout ripening

Abstract The aim of this work was to study the microbiological and physico-chemical changes in four batches of Genestoso cheese (two ripened in autumn–winter and the other two in spring–summer) throughout manufacture and ripening. In general, the pH decreased more quickly in the cheeses manufactured in spring which, moreover showed values lower in aw and higher in salt/moisture content. The highest counts of aerobic mesophilic bacteria, presumptive lactococci and presumptive leuconostoc were reached in 2 day old cheeses. Lactobacilli and fungic flora became predominant with ripening. The counts of enterococci differed between the batches, but in general the maximum counts in kanamycin aesculin azide were obtained after ripening for 2 or 7 days. The counts on mannitol salt agar were very low and disappeared in the first days of ripening. Enterobacteriaceae were not detected after 15 days of ripening in the cheeses manufactured in spring nor in the 7 day old cheeses of an autumn batch.

Microbiological study of León raw cow-milk cheese, a Spanish craft variety

The levels of several microbial groups (aerobic mesophilic flora, aerobic psychrotrophic flora, lactic acid bacteria, Micrococcaceae, enterococci, Enterobacteriaceae, and molds and yeasts), and some biochemical parameters were investigated during the manufacture and ripening of four batches of León cow cheese produced from raw milk without the addition of starter cultures. The study of the microbial characteristics of this cheese constitutes the first step towards the establishment of a starter culture which would allow the making of a product both more uniform and safer from the point of view of health. The total microbial counts were high throughout the elaboration and ripening. Almost all the microbial groups reached their maximum counts in curd and afterwards dropped throughout the ripening process. The greatest drop was shown by Enterobacteriaceae, which had disappeared after 3 months of ripening. Lactic acid bacteria were the major microbial group, reaching counts similar to the total aerobic mesophilic flora at all sampling points. Lactococcus lactis subsp. lactis dominated in milk (62.5% of the isolates obtained in de Man-Rogosa-Sharpe (MRS) agar at this sampling point), curd (82.5% of the isolates obtained at this sampling point) and one-week-old cheese (85% of isolates obtained at this sampling point), while Lactobacillus casei subsp. casei was the most predominant species in eight-week-old cheese (55% of isolates obtained at this sampling point) and twelve-week-old cheese (47.5% of isolates obtained at this sampling point). According to our data, a starter suitable for the production of León cow cheese would be made up of these two species. Some species of Leuconostoc or enterococci could also be added to this starter with the aim of improving the organoleptic characteristics of the final product or to emphasize the characteristics of this variety.

Lactic Acid Bacteria and Bifidobacteria with Potential to Design Natural Biofunctional Health-Promoting Dairy Foods

Consumer interest in healthy lifestyle and health-promoting natural products is a major driving force for the increasing global demand of biofunctional dairy foods. A number of commercial sources sell synthetic formulations of bioactive substances for use as dietary supplements. However, the bioactive-enrichment of health-oriented foods by naturally occurring microorganisms during dairy fermentation is in increased demand. While participating in milk fermentation, lactic acid bacteria can be exploited in situ as microbial sources for naturally enriching dairy products with a broad range of bioactive components that may cover different health aspects. Several of these bioactive metabolites are industrially and economically important, as they are claimed to exert diverse health-promoting activities on the consumer, such as anti-hypertensive, anti-inflammatory, and anti-diabetic, anti-oxidative, immune-modulatory, anti-cholesterolemic, or microbiome modulation. This review aims at discussing the potential of these health-supporting bacteria as starter or adjunct cultures for the elaboration of dairy foods with a broad spectrum of new functional properties and added value.

Population Levels, Species, and Characteristics of Micrococcaceae during the Manufacturing and Ripening of Armada-Sobado Hard Goat's Milk Cheese

The changes in the counts and the species of Micrococcaceae were studied throughout the manufacturing and ripening of a Spanish hard goats milk cheese, the Armada-Sobado variety. In the milk, counts on mannitol salt agar (MSA) ranged from 2 × 104 to 5 × 104 CFU/g. These counts showed the maximum value in the curd (7 × 104 to 4 × 105 CFU/g), decreasing afterwards slowly but steadily throughout the ripening process to reach final counts on average 2 logarithmic units lower than those found in the curd. Of 280 isolates obtained from MSA during manufacturing and ripening, 66 (24%) were considered to be Micrococcaceae . Staphylococcus sciuri (22.5% of the isolates at this sampling point) and Staphylococcus saprophyticus (7.5%) were the only two species of staphylococci isolated from the milk. In the curd, S. sciuri increased its proportion (30%) whilst the percentage of S. saprophyticus remained constant. None of these species was isolated from the cheese. S. aureus was detected only in curd (7.5% of the isolates obtained at this sampling point). S. xylosus , S. capitis , S. epidermidis , and S. warneri were isolated from curd and cheese, or exclusively from cheese, but always in very low proportions. Micrococcus varians (10%) and M. roseus (5%) were the two species of micrococci isolated from the milk. M. varians increased its proportion in curd (17.5%) and could not be isolated in cheese. M. roseus appeared neither in curd nor in cheese. All the isolated staphylococcal strains were tested for production of A, B, C, and D enterotoxins. The three isolated strains of Staphylococcus aureus produced A and C enterotoxins, but neither B or D. Of 41 coagulase-negative strains only two of the Staphylococcus sciuri isolated from milk produced C enterotoxins.

Molecular study of Geotrichum strains isolated from Armada cheese.

The aim of this work was the genetic characterization at the strain level of 39 presumed Geotrichum candidum isolates isolated throughout the artisanal manufacturing and ripening of Armada cheese and tentatively identified at genus and/or species level by phenotypic characteristics. The molecular identification of the strains included among others the amplification and sequencing of the D1/D2 domains of the 26S rRNA gene. A restriction fragment length polymorphism (RFLP) analysis with the ITS1-5.8S-ITS2 PCR amplicons and a randomly amplified polymorphic DNA (RAPD) analysis with five different primers were carried out. The bands pattern profile obtained through RFLP by enzymatic restriction with HinfI was the same for all the strains studied, which confirmed the classification of the strains at species level. A RAPD-PCR analysis with three different primers was applied to assess the intraspecific diversity, in this way 16 band profiles were obtained for the 39 strains studied by the combined use of primers Ari1 and Omt1. This study contributes to know the occurrence and genotypic biodiversity of G. candidum in Armada cheese.

Biogenic amines in Zamorano cheese: factors involved in their accumulation

BACKGROUND Ripened cheese is among fermented food the most often associated with food poisoning from biogenic amines. The influence of ripening time, heat treatment of milk and the effect of using milk from a different ewe breed on the biogenic amine (BA) content of Zamorano cheese was studied by high-performance liquid chromatography. Physicochemical, proteolytic and microbiological parameters were also studied. RESULTS BA content increased significantly during ripening and their final values were around 400 mg kg(-1). Cheeses elaborated with raw milk duplicated the concentration of BA relative to those elaborated with pasteurized milk (72 °C for 20 s). The average levels of putrescine, spermine and tyramine were higher in cheeses made with a greater proportion of milk from Churra breed. Significant differences in microbial counts and nitrogen soluble in 5% phosphotungstic acid were observed between the different batches. CONCLUSION Ripening time and heat treatment applied to milk were the factors that exercised the greatest influence upon the concentration of BA in Zamorano cheese.