Study of exopolysaccharides from lactic acid bacteria and their industrial applications: a review

.This review describes and discusses the structure, biosynthesis and applications of exopolysaccharidesfrom lactic acid bacteria. These substances are classified as homopolysaccharides, which are synthesisedfrom sucrose through the action of extracellular glycosyltransferases or heteropolysaccharides, which aresynthesised from repeating unit precursors formed in the cytoplasm and assembled extracellularly by thesequential addition of nucleotide sugars. The industrial application of exopolysaccharides is linked toenhancing the texture and rheological properties of certain fermented products and their productionin situbeing of particular interest. The chemical characteristics of exopolysaccharides influence interac-tions with milk proteins in fermented dairy products. These compounds reduce gel syneresis and increasethe viscosity, water retention capacity and firmness of the gel, all of which are desirable characteristics forthe development of low-fat dairy products. Similarly, they have applications in the production of gluten-free bakery products and fermented meat productsS

Production of sheep milk cheese with high γ-aminobutyric acid and ornithine concentration and with reduced biogenic amines level using autochthonous lactic acid bacteria strains

[EN] Consumer demand for health-promoting foods is generating the need to develop biofunctional dairy products. Lactic acid bacteria are employed in cheese-making and some of them are able to produce beneficial compounds on human health such as γ-aminobutyric acid (GABA) and ornithine but also to synthetize biogenic amines. The aim was to investigate the effect of four selected autochthonous co-cultures on the free amino acid profile, with special emphasis on GABA and ornithine, and on the biogenic amine content of pasteurized sheep milk cheese during ripening. High average concentrations of GABA (1296.75 mg/kg cheese) and ornithine (2355.76 mg/kg cheese) were found in all the cheese batches at 240 days of ripening. Batch 2, manufactured with the co-culture containing autochthonous Lactococcus lactis strains as starter and Lactobacillus plantarum TAUL1588 as adjunct, showed 2.37 fold reduced biogenic amines concentration with respect to the batch 1 made with the starter during the ripening time. The microstructure and microbiological counts of cheeses were affected (P≤0.001) by the ripening time, without appreciating differences (P≥0.05) in the physico-chemical composition between batches. This study could be a good approach to the development of functional sheep milk cheeseSIThe authors are grateful to the University of León (León, Spain) for granting a PhD fellowship to Erica Renes Bañuelo

Evaluation of technological properties and selection of wild lactic acid bacteria for starter culture development

[EN] Sixty-six lactic acid bacteria strains, isolated from traditional cheeses, were identified by MALDI-TOF technology, characterised through the evaluation of their enzymatic activities (acidifying and proteolytic capacities and carboxypeptidase, aminopeptidase, dipeptidase and esterase activities) and selected through a scoring system based on activity results in order to select wild strains of technological interest for cheese manufacturing. The strains were identified as Lactococcus lactis (9), Leuconostoc citreum (3), Leuconostoc mesenteroides (2), Leuconostoc pseudomesenteroides (1), Levilactobacillus brevis (7), Lactiplantibacillus plantarum (32), Lactiplantibacillus paraplantarum (7) and Lacticaseibacillus paracasei (5). In general, Lactococcus lactis strains showed the highest degree of acidifying activity, especially in the first hours of fermentation, and extracellular proteolytic activity. In contrast, intracellular activities, assayed from cell-free extracts, were higher in the lactobacilli strains. L. paracasei strains showed the highest level of aminopeptidase activity, while some L. plantarum strains obtained high values of dipeptidase activity. Carboxypeptidase activity was very low or undetectable in many strains, although in others the activity values were exceptionally high. Esterolytic activity was generally low, although L. paracasei strains showed higher activity on short-chain substrates. Finally, 11 strains were selected using the scoring system that could be used in the design of starter cultures and co-cultures.SIUniversidad de Leó

CLA-producing adjunct cultures improve the nutritional value of sheep cheese fat

peer-reviewedThe influence of the autochthonous CLA-producing Lactobacillus plantarum TAUL 1588 and Lactobacillus casei subsp. casei SS 1644 strains and the ripening time on the fatty acid (FA) content and sensory characteristics of sheep cheese were investigated. Three cheese types with different cultures and the control cheese were produced in duplicate and ripened for 8 months. 86 individual FA were determined by gas chromatography. Ripening time (2, 90, 180 and 240 days) did not have a significant effect (P > .05) on the FA content. However, the presence of both Lactobacillus CLA-producing strains led to a decrease of the saturated FA content and to 1.30, 1.19 and 1.27 times higher levels of vaccenic acid, CLA and omega-3, respectively, when compared to the control cheese. This combination allowed obtaining sheep milk cheeses with a healthier FA content, without appreciable changes on sensory characteristics. This work could be a promising approach to increase the bioactive fatty acid content of cheeses

Characteristics and proteolysis of a Spanish blue cheese made with raw or pasteurised milk

[EN] Valdeón cheese is a Spanish Protected Geographical Indication of blue-veined cheese produced on an industrial scale from raw or pasteurised cow and/or goat milk. The aim of this work was to evaluate the impact of pasteurisation on the microbiological, physicochemical and sensory characteristics of cheese. Cheeses made with raw milk showed higher counts of lactobacilli and enterococci, as well as lower values of pH and D-lactic acid and salt/moisture ratio. Cheeses made with pasteurised milk showed greater extent of proteolysis, higher concentration of free amino acids and lower concentration of biogenic amines. Pasteurisation produced more elastic and harder cheeses, but with a lower sensory profileSIJunta de Castilla y Leó

Effect of forage type in the ovine diet on the nutritional profile of sheep milk cheese fat

[EN] The high nutritional value of sheep milk can be advantageous in the manufacture of cheese, and fat plays an important role in sheep cheese properties. The aim of this study was to investigate the effect of feeding common hay or silage diets used in commercial farms on the nutritional value of sheep cheese fat. We also monitored the effect of cheese ripening period on the fatty acid profile. Cheeses were produced from milk of sheep fed hay and silage diets from 8 farms, on 4 separate occasions (February, May, August, and November) over a 1-yr period. Eighty-four individual fatty acids were determined and identified by gas chromatography. Ripening time (100 and 180 d) significantly reduced moisture, acidity, and water activity of cheeses but did not affect the fatty acid content. However, hay feeding, compared with silage feeding, led to cheeses with 1.5- and 1.3-fold higher contents of vaccenic acid and conjugated linoleic acid, without detrimental changes in saturated and n-3 (omega-3) fatty acid composition. Hay forages could be a low-cost alternative for producing cheese with a fatty acid profile suitable for human health, which is an aspect of great interest to the food industrySIThis work was supported by the Ministerio de Economía y Competitividad (Project AGL2016-75159- C2-2-R; Madrid, Spain) and the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Project TA2014-00069-CO2-02; Madrid, Spain). The authors also acknowledge Entrepinares S.A.U. Company (Valladolid, Spain) for the help in the cheese-making trial

Technological and safety assessment of selected lactic acid bacteria for cheese starter cultures design: Enzymatic and antimicrobial activity, antibiotic resistance and biogenic amine production

[EN] Twenty lactic acid bacteria (LAB) isolated from artisanal cheeses and previously selected for their technological properties were screened for their enzymatic activities, antimicrobial activity and safety. The aim was to select those LAB strains that were safe and showed advantageous properties for the development of starter cultures for cheese making, discarding those that could transfer antibiotic resistance or produce any toxic biogenic amines. Aminopeptidase activities were detected in most strains, particularly high for the substrate leucine arylamidase, and most lactobacilli and Leuconostoc strains showed high β-galactosidase activity. Glutamate dehydrogenase (GDH) activity was detected in 13 strains, although the activity values varied widely. All strains showed antimicrobial activity against the indicator microorganisms due to acid production. However, only one of the Lactiplantibacillus plantarum strains showed an inhibitory activity against Enterococcus faecalis due to bacteriocin-like compounds. In particular, Levilactobacillus brevis TAUL1567 and Lactiplantibacillus paraplantarum TAUL1399 showed resistance to tetracycline and ampicillin, respectively, above the cut-off values and were therefore excluded. Tyramine was only produced by L. brevis TAUL1567 (193.15 μg ml−1), while putrescine was produced by this strain and two strains of Lactococcus lactis. Finally, 14 strains produced γ-aminobutyric acid (GABA), five of them at concentrations around or above 100 μg ml−1.S

Changes in the Concentration and Profile of Free Fatty Acids during the Ripening of a Spanish Blue-Veined Cheese Made from Raw and Pasteurized Cow and Goat Milk

[EN]Blue-veined cheeses in general undergo a pronounced lipolysis. The aim of this work was to determine the evolution of free fatty acids (FFA) in Valdeón cheese during ripening, comparing cheeses made from raw and pasteurized milk. The effect of season on the evolution of FFA in pasteurized milk cheeses was also studied. Cheeses made with raw milk showed the highest concentrations of FFA, reaching values of 23,081.9 mg 100 g−1 dry matter at the end of ripening, compared to the values of cheeses made with pasteurized milk (7327.1 mg 100 g−1 dry matter), in both cases with a predominance of oleic and palmitic acids. However, pasteurization did not affect the FFA profile of the cheeses. Regarding the cheeses made with pasteurized milk in different seasons, the highest FFA concentration was reached in cheeses made in summer after 30 days of ripening. The season also influenced the FFA profile and thus the concentration of short-, medium- and long-chain fatty acids in relation to total FFA. There were no significant differences in sensory analysis between cheeses made from raw and pasteurized milk.SIThis work was supported by project L021A12-2 from Junta de Castilla y León

CLA-producing adjunct cultures improve the nutritional value of sheep cheese fat

[EN]The influence of the autochthonous CLA-producing Lactobacillus plantarum TAUL 1588 and Lactobacillus casei subsp. casei SS 1644 strains and the ripening time on the fatty acid (FA) content and sensory characteristics of sheep cheese were investigated. Three cheese types with different cultures and the control cheese were produced in duplicate and ripened for 8 months. 86 individual FA were determined by gas chromatography. Ripening time (2, 90, 180 and 240 days) did not have a significant effect (P >.05) on the FA content. However, the presence of both Lactobacillus CLA-producing strains led to a decrease of the saturated FA content and to 1.30, 1.19 and 1.27 times higher levels of vaccenic acid, CLA and omega-3, respectively, when compared to the control cheese. This combination allowed obtaining sheep milk cheeses with a healthier FA content, without appreciable changes on sensory characteristics. This work could be a promising approach to increase the bioactive fatty acid content of cheeses.SIThe authors are grateful to the University of León (León, Spain) for granting a PhD fellowship to Erica Renes Bañuelos. Pilar Gómez-Cortés was subsidized with a Juan de la Cierva research contract from the Ministerio de Economía y Competitividad. The authors also wish to acknowledge the Consortium for Ovine Promotion (Villalpando, Zamora, Castilla-León, Spain). The authors thank to F.J. Zorita for his technical assistance

Study of the Technological Properties of Pedrosillano Chickpea Aquafaba and Its Application in the Production of Egg-Free Baked Meringues

[EN] Aquafaba is a by-product derived from legume processing. The aim of this study was to assess the compositional differences and the culinary properties of Pedrosillano chickpea aquafaba prepared with different cooking liquids (water, vegetable broth, meat broth and the covering liquid of canned chickpeas) and to evaluate the sensory characteristics of French-baked meringues made with the different aquafaba samples, using egg white as a control. The content of total solids, protein, fat, ash and carbohydrates of the aquafaba samples were quantified. Foaming and emulsifying capacities, as well as the foam and emulsions stabilities were determined. Instrumental and panel-tester analyses were accomplished to evaluate the sensory characteristics of French-baked meringues. The ingredients added to the cooking liquid and the intensity of the heat treatment affected the aquafaba composition and culinary properties. All types of aquafaba showed good foaming properties and intermediate emulsifying capacities; however, the commercial canned chickpea’s aquafaba was the most similar to egg white. The aquafaba meringues showed less alveoli, greater hardness and fracturability and minimal color changes after baking compared with egg white meringues; the meat and vegetable broth’s aquafaba meringues were the lowest rated by the panel-tester and those prepared with canned aquafaba were the highest scored in the sensory analysisSIThis research received no external fundin