Search

There is a growing interest in finding safe and natural anti-microbial compounds as a valid alternative to conventional chemical treatments for managing post-harvest fruit diseases. This study investigated the anti-fungal capacity of orange peel polyphenolic extract (OPE) against three relevant post-harvest fungal pathogens, Monilinia fructicola, Botrytis cinerea and Alternaria alternata. OPE extract at 1.5 g/L inhibited (100%) the mycelial growth and conidial germination of the three target fungi. At lower concentration, the effect varied, depending on the dose applied and target fungi. When the anti-fungal activity of the main phenolic compounds in sweet orange peel, namely, the flavonoids (naringin, hesperidin and neohesperidin) and phenolic acids (ferulic and p-coumaric), were evaluated, ferulic acid and p-coumaric acid displayed significantly higher inhibitory capacity in synthetic medium, while the activity of flavonoids was limited. Synergism between compounds was not detected, and the inhibitory activity of OPE may be attributed to an additive effect of phenolic acids. Interestingly, in peach-based medium, ferulic acid remained active against M. fructicola and A. alternata and was more efficient than p-coumaric to control B. cinerea. These results highlight peel orange waste as an excellent source of anti-fungal compounds, suggesting the possibility of using ferulic acid or ferulic acid-rich extracts, either alone or in combination with other post-harvest treatment, as a natural alternative to reduce post-harvest losses and, also, enhance the shelf-life of fruit.

The present work was performed to study the enterobacteria involved in the ripening of the artisanal raw ewe's milk PDO cheeses 'Torta del Casar' and 'Queso de la Serena' produced in Extremadura (Spain). These isolates were strain-typed, safety tested and characterized for some important technological properties. A total of 485 enterobacterial isolates were clustered by RAPD-PCR and subsequently identified by partial sequencing of the 16S rRNA gene. Among the 17 different species identified, Hafnia paralvei was the predominant species; H. alvei and Lelliottia amnigena were present to a lesser extent. Therefore, 55 Hafnia spp. strains, selected according to their genetic profile and dairy origin, were tested for the safe application. Overall, they were able to produce the biogenic amines putrescine and cadaverine under favourable conditions, presented α-haemolytic activity and did not produce cytolytic toxin active against HeLa cells or contain virulence genes. In addition, antibiotic susceptibility profiles showed that 17 Hafnia spp. strains were less resistant to the 33 antibiotics tested; subsequently, they were further technologically characterized. Although they showed differences, in general, they were well adapted to the stress conditions of cheese ripening. Among them, two strains, H. alvei 544 and 1142, are highlighted mainly due to their proteolytic activity at refrigeration temperatures and their low or null gas production. Although further studies are necessary before industrial application, these two strains are proposed for potential use as adjunct cultures to favour the homogeneity of these PDO cheeses, preserving their unique sensory characteristics.

Serpa cheese is one of the traditional regional Portuguese cheeses having the Protected Denomination of Origin (PDO) designation. This study investigated the bacterial community in the traditional Portuguese Serpa cheese. The microorganisms identified at the end of ripening (30 days) mainly were lactic acid bacteria (LAB). Lactobacillus paracasei/Lactobacillus caseiwas the main species in cheese from PDO registered industries, whereas in non‐PDO registered industries Lactobacillus breviswas highlighted, among other LAB. Enterobacteriaceaespecies were detected at 20% to 40% of the total isolates. The results obtained by high‐throughput sequencing analysis confirmed that LAB was the main microbial group, with Lactococcusgenus contributing to approximately 40% to 60% of the population, followed by Leuconostocand Lactobacillus. The Enterobacteriaceaefamily was also important. The differences between bacterial communities from PDO and non‐PDO registered industries suggest that the lack of regulation of the cheese‐making practices may influence unfavorably. The new knowledge about bacterial diversity in Serpa cheese could be useful to set up new ripening conditions, which favor the development of desirable microorganisms. The control of the manufacturing process of traditional cheeses can be improved through the knowledge of the bacterial diversity that develops. Thus, the growth of desirable microorganisms can be promoted to homogenize the final product.

The relationship between the quality attributes and the ultrasound parameters of Protected Designation of Origin (PDO) soft-bodied cheeses from “Torta del Casar” and “Queso de la Serena” was studied. Cheese samples were taken from six different dairy industries (three for each PDO) in two different seasons. Ultrasound parameters related to velocity, attenuation and frequency were calculated and correlated with the physico-chemical, microbiological, rheological and sensorial properties of the cheeses. Several ultrasonic parameters showed a high correlation with changes in the physico-chemical, textural and sensorial properties of this product, which were partially associated with microbial activity. Among these, stand out the negative correlation of the sensorial descriptor “firmness” with bulk modulus (κ). The predictive models achieved by the multivariate linear regression method (MLR) showed the highest correlation coefficients for firmness by texture compression analysis (TCA) and the sensory descriptor “intensity”, including as the explanatory variables for both models, fast Fourier transform (FFT) frequencies and attenuation parameters. This work highlights the on-line capability of ultrasound for non-destructive quality assessment of this traditional and heterogeneous soft cheese based on the predictive potential of several secondary ultrasonic parameters.

This study investigated the yeast community in traditional soft cheese from the Extremadura region to be able to establish possible beneficial properties for human health. A total of 149 yeast isolates were characterised at strain level using the ISSR-PCR technique with the primer (GTG)5. Forty-three different genetic profiles were obtained, and the yeasts were grouped into 12 species allowing their typification at strain level. Regarding probiotic tests, 54 strains were selected for the study of probiotic properties based on genetic profile and origin. All of them showed adequate tolerance to the most restrictive stomach and bile salts conditions, although strains of Kluyveromyces lactis and Pichia fermentans presented better ability to survive to these stresses. P. fermentans was also the species that showed better antioxidant, auto-aggregation and hydrophobicity capacity, at the same time as antimicrobial activity, followed by Kluyveromyces sp. strains. Thus, considering the probiotic characteristics studied, 15 strains, P. fermentans 1826, 1865, 1859, 1911,1913, 1916 and 1938; P. kudriavzevii 1801, 1809 and 1832; K. marxianus 1886, 1917 and 1919; D. hansenii 1860; and Y. lipolytica 1961, are promising potential probiotic candidates for developing a functional cheese.

Serpa cheese is one of the traditional regional Portuguese cheeses having the Protected Denomination of Origin (PDO) designation. This study investigated the bacterial community in the traditional Portuguese Serpa cheese. The microorganisms identified at the end of ripening (30 days) mainly were lactic acid bacteria (LAB). Lactobacillus paracasei/Lactobacillus casei was the main species in cheese from PDO registered industries, whereas in non-PDO registered industries Lactobacillus brevis was highlighted, among other LAB. Enterobacteriaceae species were detected at 20% to 40% of the total isolates. The results obtained by high-throughput sequencing analysis confirmed that LAB was the main microbial group, with Lactococcus genus contributing to approximately 40% to 60% of the population, followed by Leuconostoc and Lactobacillus. The Enterobacteriaceae family was also important. The differences between bacterial communities from PDO and non-PDO registered industries suggest that the lack of regulation of the cheese-making practices may influence unfavorably. The new knowledge about bacterial diversity in Serpa cheese could be useful to set up new ripening conditions, which favor the development of desirable microorganisms.The control of the manufacturing process of traditional cheeses can be improved through the knowledge of the bacterial diversity that develops. Thus, the growth of desirable microorganisms can be promoted to homogenize the final product.

Today's growing interest in functional foods is due to their positive impacts on human health. The aim of this study was to evaluate the probiotic properties and prebiotic metabolism of autochthonous lactic acid bacteria from artisanal Serpa cheese. Twenty strains presented better tolerance to stress conditions found in the gastrointestinal tract, highlighting Lactobacillus brevis C1Lb21 for its adequate auto-aggregating ability and significantly higher hydrophobicity. However, eight strains were discarded for their antibiotic resistance and biogenic amine production. Finally, prebiotic fermentation study showed that lactulose supported better growth of lactobacilli and induced the production of short-chain fatty acids (SCFA). During lactulose fermentation, Lb. pentosus G4Lb7 produced statistically more SCFA, and Lb. plantarum G1Lb5 lactic acid. Thus, Lb. brevis C1Lb21, Lb. plantarum G1Lb5 and Lb. pentosus G4Lb7 are promising probiotic candidates, and in combination with lactulose could be used for developing a symbiotic cheese.