Microbiology and biochemistry of cheeses with appélation d’origine protegée and manufactured in the Iberian Peninsula from ovine and caprine milks

To support legal protection with objective technical data and to promote enforcement of high quality standards a few European countries have created Appe´lation d’Origine Protege´es. This paper reviews and updates fundamental and applied aspects encompassing microbiological and biochemical characteristics of traditional cheeses with Appe´lation d’Origine Protege´emanufactured in the Iberian Peninsula from ovine, caprine, or both milks. Ovine and caprine cheeses with Appe´lation d’Origine Protege´e from Portugal and Spain can be divided into four distinct groups based on milk source and rennet type: 1) Azeita˜ o, Castelo Branco, E´ vora, Nisa, Serpa, Serra da Estrela, and La Serena cheeses are manufactured with raw ovine milk and coagulated via plant rennet; 2) Terrincho, Idiaza´ bal, Manchego, Roncal, and Zamorano cheeses are manufactured with raw ovine milk and coagulated via animal rennet; 3) Cabra Transmontano and Majorero are manufactured with raw caprine milk and coagulated via animal rennet; and 4) Amarelo da Beira Baixa, Picante da Beira Baixa, and Rabac˛al are manufactured with mixtures of raw ovine and caprine milks and coagulated via animal rennet. (Key words: dairy foods, enzyme, microflora, Mediterranean) Abbreviation key:AOP = Appe´lation d’Origine Protege ´e, FA = fat acidity, LAB = lactic acid bacteria, TN = total nitrogen, WSN = water-soluble nitrogen, WSP = water-soluble peptides

Technological optimisation of Picante cheese using microbiological, chemical and physical criteria

In order to optimise the final quality of Picante cheese, several processing parameters (i.e., volumetric fraction of caprine milk, ripening time and percentage of salt added to fresh cheese) were manipulated and gave rise to a number of experimental cheeses produced according to a second-order, composite factorial design. Microbiological, physicochemical, biochemical and textural analyses were carried out in samples from all experimental cheeses. The most important effect in microbiological terms was produced by ripening time, in both linear and quadratic forms; caprine milk fraction and amount of salt added were also found to be significant factors, again in both linear and quadratic forms, especially with respect to total viable mesophilic microorganisms, Enterobacteriaceae and staphylococci. In terms of proteolysis and lipolysis, ripening time was the dominant factor, but caprine milk fraction and NaCl content were also significant at the 5% level. A higher content of caprine milk was associated with higher extents of proteolysis and lipolysis, but the reverse held for NaCl content. It was concluded that 50–80% (v/v) caprine milk, ripening for 195 days and 15% (w/wTS) NaCl provide safe counts of Enterobacteriaceae and staphylococci, while maximising proteolysis and lipolysis in Picante cheese

Influence of milk type, coagulant, salting procedure and ripening time on the final characteristics of picante cheese

Picante da Beira Baixa cheese is a hurd, spicy, salty traditional cheese with a minimum ripening time of 120 d that is manufactured in Portugal at a farm level 0nly. The purpose of this work was to study the influence of several manufacturing conditions (viz. mixture of ovine and caprine milks, source of coagulant, level of NaCl addition, and duration of ripening period) on the final characteristics of this cheese following a (replicated) factorial design. Milk type proved to be a statistically significant technological parameter in terms of numbers of viable microorganisms of various genera and the extent of proteolysis, probably us u consequence of higher initial contamination of caprine milk. The type of coagulant ad a major effect on proteolysis: values of water-soluble nitrogen for cheeses coagulated with animal rennet were in general lower than those for cheeses coagulated with plant rennet, but much smaller differences were detected between values of non-protein nitrogen; and breakdown of a3 and b-caseins was more extensive in Picante cheeses manufactured with plant rennet. The level of NaCl was a statistically significant parameter ,for all microbiological, physicochemical and chemical Characteristics measured, an observation that is probably due to its capacity to reduce water activity. Ripening time did not have a significant effect on the numbers of viable staphylococci

Michaelis-menten kinetics: explicit dependence of substrate concentration on reaction time

The nonlinear dependence of the rate expressions associated with enzymecatalysed reactions on the concentration of substrate implies that the corresponding integrated form of the substrate mass balance in a batch reactor cannot be expressed as an explicit function of time..This paper addresses this problem for the classical case of Michaelis—Menten kinetics by providing a self-pacing exploration of the characteristics of a Taylor expansion of the substrate concentration on time. The accuracy of such an approximation is discussed. The procedure presented is appropriate to model situations of technological and practical interest

Dominant microflora of picante cheese: Independent role upon proteolysis and lipolysis in model systems

Four species of bacteria (two species of enterococci, Enterococcus faecium and Enterococcus faecalis, and two species of lactobacilli, Lactobacillus plantarum and Lactobacillus paracasei) and three species of yeasts (Debaryomyces hansenii, Yarrowia lipolytica and Cryptococcus laurentii), previously isolated from Picante cheese were assayed for biochemical performance in proteolysis and lipolysis. In addition to the difference of the microbiological strains, the milk type (caprine or ovine), the ripening time (0 to 65 days) and the concentration of NaCl (0 to 14%(w/v)) have been deliberatly fixed in vitro curdled milk (previously prepared from heat-sterilized milk, coagulated with animal rennet and inoculated with each strain) and subject to 12 ºC. High proteolytic activity was demonstrated by Y. lipolytica and by all the other strains to a lesser extent; Y. lipolytica produced ca. 85% of WSN by 65 days of ripening whereas E. faecium, D. hansenii and C. laurentii produced levels of WSN ranging in 40-50%, and E. faecalis, L. plantarum and L. paracasei in 30- 40%. In terms of peptidolytic activity, measured by NPN contents and by release of free amino acids, once again Y. lipolytica presented the highest activity, followed by L. plantarum, L. paracasei, E. faecium and E. faecalis. Milk type, ripening time, and content of NaCl revealed to be statistically significant processing factors in terms of proteolysis; caprine milk, 65 days of ripening and lower contents of NaCl led to the highest values. The lipolytic activity, assessed by the release of butyric acid from tributyrin, was strong for Y. lipolytica and C. laurentii, whereas release of free fatty acids was observed at different rates for all strains under study. Ripening time proved to be a statistically significant factor for lipolysis, whereas milk type was not; lipolytic activities, measured as fat acidity index, were strongly affected by NaCl content and, as happened with release of free amino acids, the extent of fat hydrolysis was much more affected by the increase of NaCl from 0 to 7% than by its increase from 7% to 14%. Although it is not possible to directly compare results obtained in vitro using pure, single cultures with those obtained in loco using actual cheese, our results suggest that a mixed-strain starter for Picante cheese including L. plantarum, E. faecium (or E. faecalis) and D. hansenii (and/or Y. lipolytica) would be of potential interest.info:eu-repo/semantics/publishedVersio

Fluoxetine and Nutrients Removal from Aqueous Solutions by Phycoremediation

The tertiary treatment using microalgae offers an attractive alternative to the removal of low but relevant concentrations of pharmaceuticals from domestic wastewaters. The removal of fluoxetine from aqueous solutions by living and non-living (lyophilized) Chlorella vulgaris was assessed. The determination of the pH at the point of zero charge, Fourier transmittance infrared analysis, and scanning electron microscopy were performed to characterize the microalgae biomass. Kinetic and equilibrium experiments were performed. The pseudo-second-order model described the kinetics of fluoxetine. The corresponding kinetic constants indicated that biosorption was faster onto non-living biomass than onto living biomass. The equilibrium results showed that the systems followed the Langmuir isotherm model. The maximum capacity of living microalgae (1.9 ± 0.1 mg·g−1) was slightly higher than the non-living microalgae (1.6 ± 0.2 mg·g−1). Living Chlorella vulgaris, free and immobilized in calcium-alginate, were also used to remove fluoxetine and nutrients (nitrogen and phosphorus) from treated municipal wastewater in a batch system. In both experiments, fluoxetine was completely removed within six days. The total phosphorus (TP) and total nitrogen (TN) removal efficiencies achieved for free and immobilized cells were, null and 65.0 ± 0.1%, and 86.2 ± 0.1% and 81.8 ± 3.1, respectivelyThis research was funded by the Associate Laboratory for Green Chemistry-LAQV, which received financial support from UIDB/50006/2020, UIDP/50006/2020, and LA/P/0008/2020 by the Fundação para a Ciência e a Tecnologia (FCT)/Ministério da Ciência, Tecnologia e En sino Superior (MCTES) through national funds. This research was also funded by the EU and FCT/UEFISCDI/FORMAS, in the frame of the collaborative international consortium REWATER— “Sustainable and safe water management in agriculture: increasing the efficiency of water reuse for crop growth while protecting ecosystems, services and citizens’ welfare” (WaterJPI/0007/2016), which was financed under the ERA-NET Co-fund WaterWorks2015 Call, as an integral part of the 2016 Joint Activities developed by the Water Challenges for a Changing World Joint Program Initiative (Water JPI). The research was funded also by FCT and BiodivRestore Joint Call 2020–2021-European Union’s Horizon 2020 research and innovation program under grant agreement No. 101003777- BiodivRestore-406/DivRestore/0002/2020-BioReset-“Biodiversity restoration and conservation of inland water ecosystems for environmental and human well-being”. A.D.M. Silva would like to thank FCT for her Ph.D. Grant SFRH/BD/138/780/2018. The authors are greatly indebted to all financing sources. The authors are grateful to Materials Centre of the University of Porto (CEMUP), Porto, Portugal, for expert assistance with SEM/EDSinfo:eu-repo/semantics/publishedVersio

Dominant microflora of Picante cheese: effects on proteolysis and lipolysis

Four species of bacteria (Enterococcus faecium and E. faecalis, Lactobacillus plantarum and L. paracasein and three species of yeasts (Debaryomyces hansenii, Yarrowia lipolytica and Cryptococcus laurentiU previously isolated from Picante cheese, were assayed for proteolysis and lipolysis. Milk type (caprine or ovine), ripening time (0 to 65 d) and concentration of NaCl (0 to 14 %(w/v)) have been assessed in terms of their effects upon in vitro curdled milk. Good evidence of proteolytic and peptidolytic activities was provided for Y. lipolytica, and at much lower levels for the other strains. Milk type, ripening time and content of NaCl appeared to be statistically significant processing factors in terms of proteolysis. Clear lipolytic activity was detected for Y. lipolytica, but release of free fatty acids to lesser extents was also observed for the other strains under study. Ripening time was statistically significant with regard to lipolysis but milk type was not. Lipolytic activities were strongly affected by presence of NaCl. According to experimental results, it is suggested that a mixed-strain starter for Picante cheese including L. plantarum, E. faecium (or E. faecalis,) and D. hansenii (and/or Y. lipolyticaj is of potential interest.info:eu-repo/semantics/publishedVersio

Role of dominant microflora of Picante cheese on proteolysis and lipolysis

Four species of bacteria (Enterococcus faecium and E. faecalis, Lactobacillus plantarum and Lb. paracasei) and three species of yeasts (Debaryomyces hansenii, Yarrowia lipolytica and Cryptococcus laurentii) isolated from Picante cheese were assayed for proteolytic and lipolytic activities. The milk type (caprine or ovine), the ripening time (0–65 d) and the concentration of NaCl (0–14% (w/v)) have been studied in terms of their effects upon in vitro curdled milk. Proteolytic and peptidolytic activities were demonstrated to be high for Y. lipolytica, and at much lower levels for the other strains. Milk type, ripening time and content of NaCl appeared to be statistically significant processing factors in terms of proteolysis. Clear lipolytic activity was detected for Y. lipolytica, but release of free fatty acids to lesser extents was observed for the other strains under study. Ripening time was statistically significant for lipolysis but milk type was not. Lipolytic activities were strongly affected by NaCl content and the extent of fat hydrolysis was affected by the increase of NaCl from 0 to 7% (w/v) more than by change from 7 to 14% (w/v). In view of the experimental results, a mixed-strain starter for Picante cheese including Lb. plantarum, E. faecium (or E. faecalis) and D. hansenii (and/or Y. lipolytica) is of potential interest