Production of low-cholesterol butter with Lacticaseibacillus paracasei immobilized in calcium-alginate beads.

This study focused on the application of three strains of Lacticaseibacillus paracasei to assimilate cholesterol in cream and butter. The strains were enclosed in calcium-alginate beads and incubated in cream at 30 °C for 15 h. Immobilization of lactobacilli cultures in calcium-alginate beads resulted in a 23% reduction in cholesterol (p < 0.05) in cream, whereas a negligible reduction was observed in cream fermented with free cells. Butter with a 44% reduction in cholesterol was produced from fermented cream by L. paracasei L2A21K5 entrapped in alginate beads. No significant (p > 0.05) changes in the fatty acid profile were observed in the low-cholesterol butter, except for a slight but significant increase in n-3 fatty acids (p < 0.05). In addition, the indices of atherogenicity and thrombogenicity were significantly reduced in the low-cholesterol butter (p < 0.05). Panelists rated the low-cholesterol butter as good in appearance, consistency, and flavor.

A rapid screening method to evaluate acidifying activity by lactic acid bacteria.

The determination of pH in fermented milk is an important parameter for monitoring the production of acid by lactic acid bacteria (LAB). In this work, a colorimetric method is proposed that allows a fast determination of LAB acidification ability by evaluation of pH drop in whey fermentation. The proposed method uses spectrophotometry to measure the pH change by bacteria and uses bromocresol purple as a pH indicator dye. The absorbance at 430 nm of a buffer solution with bromocresol purple was found to be correlated with pH values. This colorimetric assay was linear within the pH range of 4.6-7.0. Upon regression analysis, linear equation y = -0.1267× + 0.9196 was obtained having r2 value of 0.9927. The assay was validated by the use of LAB fermentation in sweet whey and comparison to the values obtained by glass electrode/pH meter. Estimation of acidification activity of LAB in whey was found to be similar in both methods (r = 0.801, p > 0.05). The proposed procedure presents a viable alternative to the measurement of pH by the standard method and allows the simultaneous and fast screening of LAB acidifying activity.

Is there an association between the use of antidepressants and complications involving dental implants? A systematic review and meta-analysis.

The aim of this systematic review was to evaluate published evidence on the association between the use of antidepressants and complications involving dental implants. Two reviewers independently performed electronic searches of the MEDLINE/PubMed, Cochrane Library, and Scopus databases for relevant articles published up to May 30, 2019. This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The Newcastle-Ottawa Scale was used for the appraisal of the methodological quality of the studies included. A meta-analysis was performed to determine the risk of dental implant failure in individuals taking antidepressants. Five comparative observational studies were selected for this review; these included a total of 2056 participants with 5302 implants. The results suggest a risk ratio of 3.73 (95% confidence interval 1.85-7.52, P=0.0002) for implant failure in antidepressant users submitted to oral rehabilitation when compared to non-users. However, these studies did not present methodological rigour or standardize the drugs used. Thus, there is insufficient evidence for an association between antidepressant use and dental implant complications.

Histamine and cholesterol lowering abilities of lactic acid bacteria isolated from artisanal Pico cheese.

AIMS: This study was designed to select lactic acid bacteria with histamine- and cholesterol-reducing abilities to be used as potential probiotics. METHODS AND RESULTS: Thirty strains of lactic acid bacteria isolated from an artisanal raw milk cheese were screened for their abilities to degrade histamine, reduce cholesterol and hydrolyse bile salts. Strains were also screened for safety and probiotic traits, such as resistance to gastrointestinal conditions, adhesion to Caco-2 cells, resistance to antibiotics and presence of virulence genes. Two Lactobacillus paracasei strains presented high cholesterol- and histamine-lowering abilities, tested negative for the presence of virulence genes and showed susceptibility to most important antibiotics. These strains were also shown to possess desirable in vitro probiotic properties, revealed by tolerance to gastrointestinal conditions and high adhesion to intestinal cells. CONCLUSIONS: Among the screened strains, Lb. paracasei L3C21M6 revealed the best cholesterol and histamine reducing abilities together with desirable probiotic and safety features to be used in food applications. SIGNIFICANCE AND IMPACT OF THE STUDY: The strain L3C21M6 is a good candidate for use as a probiotic with histamine-degrading activity and cholesterol lowering effect. In addition, this strain could be use in dairy foods to prevent histamine food poisoning.

Isolation and characterization of an exopolysaccharide-producing Leuconostoc citreum strain from artisanal cheese.

High molar mass exopolysaccharides (EPS) produced from sucrose by lactic acid bacteria (LAB) are of great interest as natural additives to use in foods, medical and pharmaceutical industry. This study aimed to identify the EPS produced by Leuconostoc citreum L3C1E7 isolated from Pico cheese and characterize the strain for technological and probiotic potential. Purified EPS was isolated from the culture of L. citreum L3C1E7 by ethanol precipitation, with a yield of 520 mg ml-1 . The EPS-producing strain had a mucoid phenotype and average molecular weight of 5·88 × 106  Da. The structural characterization of the purified EPS was determined by 1 H, 13 C and two-dimensional NMR spectroscopy. EPS was composed of alternating α-(1→6)-linked and α-(1→3)-linked D-glucopyranyl units, suggesting the existence of an alternan. The strain was slow acidifying, produced diacetyl and displayed high esterase/lipase and aminopeptidase activities, which promote the desirable flavours in dairy products. Moreover, L. citreum showed moderate resistance to the adverse conditions of the gastrointestinal (GI) tract and high adhesion to GI cells. This work provides a better understanding of EPS produced by L. citreum and the potential application of EPS-producing strain in food and/or as a probiotic culture. SIGNIFICANCE AND IMPACT OF THE STUDY: Some LAB strains are known to use extracellular glycoside-hydrolase enzymes for synthesizing a diversity of exopolysaccharides (EPS) with potential application as natural additives to foods. Previous studies have identified an EPS-producing Leuconostoc citreum strain with immunomodulatory properties. This work provides a better understanding of EPS produced by this strain and the potential application of the strain in food fermentation and/or as a probiotic culture.

Genetic diversity, safety and technological characterization of lactic acid bacteria isolated from artisanal Pico cheese.

A total of 114 lactic acid bacteria were isolated at one and 21 days of ripening from a traditional raw cow's milk cheese without the addition of starter culture, produced by three artisanal cheese-makers in Azores Island (Pico, Portugal). Identification to species and strain level was accomplished by16S rRNA gene and PFGE analysis. Carbohydrate utilization profiles were obtained with the relevant API kits. Isolates were evaluated according to safety and technological criteria. The most frequently observed genus identified by 16S rRNA sequencing analysis was Enterococcus, whereas API system mostly identified Lactobacillus. The highest percentages of antibiotic resistance were to nalidixic acid (95%), and aminoglycosides (64-87%). All isolates were sensitive to several beta-lactam antibiotics and negative for histamine and DNase production. Gelatinase activity was detected in 49.1% of isolates, 43% were able to degrade casein and 93% were α-hemolytic. Most enterococci presented virulence genes, such as gelE, asaI, ace. Diacetyl production was found to be species dependent and one strain (Leu. citreum) produced exopolysaccharides. Selected strains were further studied for technological application and were found to be slow acid producers in milk and experimental cheeses, a desirable trait for adjunct cultures. Two strains were selected on the basis of technological and safety application as adjunct cultures in cheese production and presented the best cheese aroma and flavor in consumer preference tests. This is the first effort to characterize Pico cheese LAB isolates for potential application as adjunct cultures; the results suggest the potential of two strains to improve the quality of this traditional raw milk product.

Safety and technological properties of bacteriocinogenic enterococci isolates from Tunisia.

AIMS: To investigate the safety and technological traits of previously isolated bacteriocinogenic enterococci strains for potential use as starter/adjunct cultures in foods. METHODS AND RESULTS: Fifty-five bacteriocinogenic enterococci strains previously isolated from different origins in Tunisia were screened for safety. Twenty-two strains did not harbour the genes coding for virulence traits, were susceptible to relevant antibiotics such as vancomycin, and tested negative for haemolysis, histamine production, gelatinase activity and DNase activity. These strains were further assessed for some technological properties, demonstrating low milk-acidifying ability, low proteolytic activity, high peptidolytic activity and diacetyl production in milk. CONCLUSIONS: This study revealed that 22 bacteriocinogenic enteroccoci strains did not present virulence features and could be safely applied in food preservation. Some strains also showed good technological potential as adjunct/protective cultures in milk fermentation and cheese production. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of very few studies that identified safe Enterococcus strains capable of producing a wide variety of enterocins against different spoilage and pathogenic micro-organisms that have good potential for application as adjunct/protective cultures in foods.

Short communication: Latin-style fresh cheese enhances lactic acid bacteria survival but not Listeria monocytogenes resistance under in vitro simulated gastrointestinal conditions.

Different studies in humans have provided evidence about the health benefits of probiotics. However, most probiotic strains do not maintain good viability in the harsh conditions of the gastrointestinal tract (GIT). In the present study, Latin-style fresh cheese produced with potential probiotic bacteria was tested to evaluate this cheese type as a food carrier for the delivery of viable microorganisms after exposure to simulated GIT conditions. The resistance of 28 lactic acid bacteria (LAB) strains and Listeria monocytogenes upon exposure to acidic conditions (pH 2.5) and bile and pancreatic enzymes (0.3% of bile salts and 0.1% of pancreatin) was evaluated in vitro. When compared with fresh cultures, fresh cheese greatly improved LAB survival to simulated GIT conditions, as no loss of viability was observed in either acidic conditions (pH 2.5) or bile salts and pancreatin environment over a 3-h period. In opposition, L. monocytogenes did not survive after 1h under acidic conditions. These data demonstrated that Latin-style fresh cheese could play an important role in probiotic protection against gastrointestinal juices, enhancing delivery within the gut and thereby maximizing potential health benefits of LAB.

Control of Listeria monocytogenes in fresh cheese using protective lactic acid bacteria.

In the past years, there has been a particular focus on the application of bacteriocins produced by lactic acid bacteria (LAB) in controlling the growth of pathogenic bacteria in foods. The aim of this study was to select LAB strains with antimicrobial activity, previously isolated from a traditional Azorean artisanal cheese (Pico cheese), in order to identify those with the greatest potential in reducing Listeria monocytogenes in fresh cheese. Eight bacteriocin producer strains identified as Lactococcus lactis (1) and Enterococcus faecalis (7) were tested. In general, the bacteriocin-producing strains presented a moderate growth in fresh cheese at refrigeration temperatures (4 °C), increasing one log count in three days. They exhibited slow acidification capacity, despite the increased production of lactic acid displayed by some strains after 24h. Bacteriocin activity was only detected in the whey of fresh cheese inoculated with two Enterococcus strains, but all cheeses made with bacteriocin-producing strains inhibited L. monocytogenes growth in the agar diffusion bioassay. No significant differences were found in overall sensory evaluation made by a non-trained panel of 50-52 tasters using the isolates as adjunct culture in fresh cheese, with the exception of one Enterococcus strain. To test the effect of in situ bacteriocin production against L. monocytogenes, fresh cheese was made from pasteurized cows' milk inoculated with bacteriocin-producing LAB and artificially contaminated with approximately 10(6) CFU/mL of L. monocytogenes. The numbers of L. monocytogenes were monitored during storage of fresh cheese at refrigeration temperature (4 °C) for up to 15 days. All strains controlled the growth of L. monocytogenes, although some Enterococcus were more effective in reducing the pathogen counts. After 7 days, this reduction was of approximately 4 log units compared to the positive control. In comparison, an increase of 4 log CFU/mL in pathogen numbers was detected over the same period, in the absence of bacteriocin-producing LAB. The combination of two bacteriocin producing Enterococcus sp. optimized the reduction of L. monocytogenes counts in fresh cheese, reducing by approximately 5 log units after 7 days. The present work demonstrates that using bacteriocin-producing strains in the manufacture of fresh cheese might contribute to preventing the growth of undesirable pathogenic bacteria such as L. monocytogenes. A blend of two strains demonstrated great potential as a protective culture for the cheese making process.

Effect of corn supplementation of grass finishing of Holstein bulls on fatty acid composition of meat lipids.

Finishing Holstein young bulls exclusively on pasture generally results in very lean carcass and meat, but corn supplementation is expected to simultaneously improve carcass traits and intramuscular lipids (IML). The expected increase in IML would allow for a larger 18:2c9,t11 (CLA) deposition in meat without affecting the n-3 PUFA present in LM phospholipids (PL). Holstein bulls (n = 33) with initial BW of 423 ± 52.4 kg reared exclusively on pasture were assigned to 1 of 3 finishing period (85 d) diets: finished exclusively on pasture (P0) or finished on pasture and individually supplemented with 4 (P4) or 8 kg/d (P8) of ground corn. Final BW (546 ± 56.3 kg) was not affected (P > 0.05) by corn supplementation, but ADG increased (P < 0.01) with the increasing corn supplementation level from 1.23 kg/d for P0 to 1.44 kg/d for P4 and to 1.67 kg/d for P8. Subcutaneous fat depth in P0 bulls was 0.8 mm and increased (P < 0.001) in both P4 (2.9 mm) and P8 (2.7 mm) bulls, but no difference (P = 0.73) was observed between P4 and P8 bulls. Similarly, the IML increased with corn supplementation, from 1.84 g/100 g muscle in P0 to 2.96 in P4 and to 3.24 in P8, but no difference (P = 0.55) was found between P4 and P8 bulls. Corn supplementation decreased (P < 0.01) 18:1t11 in neutral lipids (NL) but not 18:2c9,t11 (P > 0.34). The 18:1t10 (mg/g total NL fatty acid [FA] ± SEM) were 2.5 ± 0.13 in P0, 5.5 ± 1.68 in P4, and 14.8 ± 3.18 in P8 bulls, being greater in P8 compared with P4 (P = 0.02). Total FA in muscle PL and SFA were unaffected, but increasing corn supplementation resulted (P < 0.001) in an increase of 18:2n-6 in PL by replacement of mostly the 18:1c9 and 18:3n-3. Notably, the total number of cis double bonds present in FA of PL remained constant (P = 0.74) with corn supplementation. Compared with P0, corn supplementation maintained (P > 0.05) the high n-3 PUFA content in meat (mg/100 g meat) and increased the 18:2c9,t11 (P = 0.028) and 18:1c9 (P < 0.001). However, increasing corn supplementation from 4 to 8 kg/d increased the 18:1t10 (P = 0.031) and had no effect on 18:2c9,t11. Therefore, supplementing grass-finished Holstein bulls with moderate amounts of ground corn (4 kg/d) increased carcass fat cover and IML, maintained n-3 PUFA, and increased 18:2c9,t11 content in meat, whereas greater corn supplementation (8 kg/d; P8) resulted in no further improvements.

Technological properties of bacteriocin-producing lactic acid bacteria isolated from Pico cheese an artisanal cow's milk cheese.

AIM: Evaluate technologically relevant properties from bacteriocin-producing strains to use as starter/adjunct cultures in cheese making. METHODS AND RESULTS: Eight isolates obtained from Pico cheese produced in Azores (Portugal) were found to produce bacteriocins against Listeria monocytogenes and three isolates against Clostridium perfringens. They were identified as Lactococcus lactis and Enterococcus faecalis and submitted to technological tests: growth at different conditions of temperature and salt, acid production, proteolysis, lipolysis, coexistence, enzymatic profile and autolytic capacity. Safety evaluation was performed by evaluating haemolytic, gelatinase and DNase activity, resistance to antibiotics and the presence of virulence genes. Some isolates presented good technological features such as high autolytic activity, acid and diacetyl production. Lactococcus lactis was negative for all virulence genes tested and inhibit the growth of all Lactic acid bacteria (LAB) isolates. Enterococci were positive for the presence of some virulence genes, but none of the isolates were classified as resistant to important antibiotics. CONCLUSIONS: The bacteriocin-producing Lc. lactis present good potential for application in food as adjunct culture in cheese production. The study also reveals good technological features for some Enterococcus isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacteriocin-producing strains presented important technological properties to be exploited as new adjunct culture for the dairy industry, influencing flavour development and improve safety.

Consumption of high energy maize diets is associated with increased soluble collagen in muscle of Holstein bulls.

The aim was to investigate whether energy supplementation of gazing bulls can influence collagen concentration and solubility in three different muscles: longissimus dorsi (LD), semitendinosus (ST) and supraspinatus (SS). Thirty three Holstein bulls aged 15 months and reared on grass, were randomly assigned to three treatment groups for 85 days: fed grass ad libitum (G1-control); fed grass ad libitum and supplemented with 4 kg day(-1) of ground maize (G2); fed grass ad libitum and supplemented with 8 kg day(-1) of ground maize (G3). Total collagen content did not differ (P>0.05) among treatments, however, soluble (heat-labile) collagen was significantly (P<0.001) higher in meat from G3 (34%, 23% and 25% for LD, ST and SS, respectively), compared with G1-control (24%, 18% and 17% in LD, ST and SS, respectively). Overall, these results suggest that meat tenderness of grazing bulls may be improved by supplementing with ground maize (8 kg day(-1)).