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

Effect of autochthonous starter and non‐starter cultures on the physicochemical, microbiological and sensorial characteristics of Castellano cheese

[EN] The effect of different combinations of starter and non-starter lactic acid bacteria on the physicochemical, colour, microbiological and sensory characteristics of Castellano cheese was investigated. Five batches of Castellano cheese were produced from pasteurised sheep's milk. Significant differences in pH, titratable acidity, microbial counts and sensory attributes between the cheese batches made with different starter cultures were found. In conclusion, the incorporation of autochthonous non-starter lactic acid bacteria strains gave cheeses made with pasteurised milk better flavour and aroma characteristics than the batch made only with commercial starter cultureSIPublicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL

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

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

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

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

Are Consumers Aware of Sustainability Aspects Related to Edible Insects? Results from a Study Involving 14 Countries

In recent years, edible insects have been suggested as an alternative food that is more sustainable compared with other sources of animal protein. However, knowledge about the sustainability aspects associated with this source of food may play a role in convincing consumers to adopt insects as part of their diet. In this context, the present study investigated the level of knowledge about the sustainability of edible insects in a group of people originating from 14 countries, with some naturally entomophagous and others not. To measure the knowledge, 11 items were selected and the scores obtained were tested with statistical tools (t-test for independent samples, analysis of variance—ANOVA) to search for differences according to sociodemographic and socioeconomic characteristics, geographical origin, and consumption habits of edible insects. The obtained results showed that, in general, knowledge is moderate, with the values of the average scores for the 11 items investigated ranging from 0.23 ± 0.99 to 0.66 ± 1.02, on a scale ranging from –2 (=very low knowledge) to 2 (=very high knowledge). The highest scores were found for items relating to the lower use of animal feed and lower emission of greenhouse gases required for the production of insects compared with beef. When investigating the differences between groups of participants, significant differences were generally found, revealing a trend for higher knowledge among males and young adults, for participants residing in urban areas and in countries such as Spain, Mexico, and Poland, and for participants with higher education levels and higher incomes. When testing the influence of consumption variables on the level of knowledge, the results showed a higher knowledge for participants who had already consumed insects or are willing to consume them. Finally, it was observed that higher knowledge was found for participants whose motivation to consume insects related to curiosity, a wish to preserve the planet, the gastronomic characteristics of insects, and their nutritional value. In conclusion, these results clearly indicate a very marked influence of a number of variables on the knowledge about the sustainability of edible insects, and this may be helpful to delineate strategies to effectively raise knowledge and eventually increase the willingness to consider insects as a more sustainable alternative to partially replace other protein foods, even in countries where this is a not a traditional practice.info:eu-repo/semantics/publishedVersio

Estudio fenotípico y genético de la producción de aminas biógenas en Enterococcus sp. aislados de quesos tradicionales

Trabajo presentado al XXII Congreso Nacional de Microbiología de los Alimentos, celebrado en Jaén (España), del 12 al 15 de septiembre de 2022Enterococcus es el tercer género más amplio de las bacterias lácticas (BAL) que está presente como parte de la microbiota de la leche. Debido a su ubicuidad, su papel es esencial en productos lácteos artesanales como los quesos, especialmente en aquellos elaborados a partir de leche cruda, donde tienen un papel importante en la maduración [1]. Los enterococos definen la textura y las propiedades sensoriales del queso, gracias a su elevada actividad proteolítica; e influyen en su microbiota, debido a su capacidad de producir bacteriocinas. Sin embargo, la presencia de enterococos en el queso puede producir la acumulación de aminas biógenas (BAs), lo cual puede provocar intoxicaciones de considerable gravedad [2]. El objetivo de este trabajo fue detectar fenotípicamente y genéticamente la producción de BAs en cepas de Enterococcus aisladas de quesos artesanales elaborados con leche cruda.Los autores agradecen a la Universidad de León la beca para estudios de doctorado otorgada a Daniel Abarquero, recogida en el marco del Programa Propio de ayudas a la Investigación de la Universidad de León

Influence of the Breed of Sheep on the Characteristics of Zamorano Cheese

This work aimed to study the effects of using ewe’s milk from Churra, Assaf, or both breeds on the physicochemical and sensory characteristics of Zamorano cheese at the end of ripening. Zamorano cheese is a hard variety with protected designation of origin (PDO) produced in the province of Zamora (Spain) with raw or pasteurized ewe’s milk. Five batches of Zamorano cheese were produced with pasteurized ewe’s milk. One batch was elaborated using milk from the Churra breed, the other using milk from the Assaf breed, and the remaining three employed milk mixtures of Churra and Assaf breeds in the proportions 75:25, 50:50 and, 25:75, respectively. Cheeses made with a higher proportion of Churra milk showed a predominance of hydrophilic peptides, while hydrophobic peptides predominated in cheeses with a greater percentage of milk from the Assaf breed. The largest content of most free amino acids was found in cheeses produced with the highest percentage of Churra milk. These cheeses presented the highest values for fat acidity index and free fatty acids content and showed greater elasticity and adhesiveness, as well as lower granularity and hardness. In the sensory evaluation, aftertaste and persistence were higher in these cheeses, being scored with the best overall values

Effect of forage type, season, and ripening time on selected quality properties of sheep milk cheese

The aim of this research was to study changes in the microbial populations, free AA profile, biogenic amine content, and sensory characteristics of ripened cheeses (100 and 180 d) produced in different seasons (summer, autumn, winter, and spring) from pasteurized sheep milk from 8 commercial flocks fed hay or silage diets. Twenty-one individual AA and 6 biogenic amines were determined by ultra-high performance liquid chromatography. Type of conserved forage for sheep feeding did not affect the variables studied, which is of great interest because hay and silage are low-cost ingredients for sheep feeding. Proteolysis led total free AA concentrations ranging between 35,179.26 and 138,063.71 mg/kg of cheese at 180 d of ripening. γ-Aminobutyric acid, which has been associated with beneficial effects on human health, was the second most abundant AA in all cheese samples, accounting for 15% of total free AA. Spring cheeses showed 2-fold higher concentrations of γ-aminobutyric acid than summer and autumn cheeses at the end of ripening. Overall, spring, winter, and autumn cheeses had lower average concentration of biogenic amines (431.99 mg/kg of cheese) than summer cheeses (825.70 mg/kg of cheese) as well as better sensory characteristics. Therefore, this study could provide the dairy industry with useful information for producing cheeses with valuable nutritional and sensory quality for consumers.This work was supported by the Ministerio de Economia y Competitividad (project AGL2016-75159-C2-2-R; Madrid, Spain) and the Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (project TA2014-00069-CO2-02; Madrid, Spain)