Effects of fermentation conditions on the potential anti‐hypertensive peptides released from yogurt fermented by Lactobacillus helveticus and Flavourzyme®

This study investigates the effects of fermentation conditions on the production of angiotensin‐converting enzyme inhibitory (ACE‐I) peptides in yogurt by Lactobacillus helveticus 881315 (L. helveticus) in the presence or absence of Flavourzyme^®, which is derived from a mould, Aspergillus oryzae and used for protein hydrolysis in various industrial applications. Optimal conditions for peptides with the highest ACE‐I activity were 4% (v/w) inoculum size for 8 h without Flavourzyme^® supplementation, and 1% inoculum size for 12 h when combined with Flavourzyme^®. The yogurt fermented by L. helveticus resulted in IC₅₀ values (concentration of inhibitor required to inhibit 50% of ACE activity under the assayed conditions) of 1.47 ± 0.04 and 16.91 ± 0.25 mg mL^?1 with and without Flavourzyme^® respectively. Seven fractions of ACE‐I peptides from the yogurt incorporated with L. helveticus and Flavourzyme^® were separated using the preparative high‐performance liquid chromatography. Fraction (F3) showed the highest ACE‐I activity with an IC₅₀ of 35.75 ± 5.48 μg mL^?1. This study indicates that yogurt may be a valuable source of ACE‐I peptides, which may explain the outcomes observed in the experimental and clinical studies and foresee the application of fermented milk proteins into functional foods or dietary supplements.     

Effect of Lactobacillus plantarum on the survival of acid‐tolerant non‐O157 Shiga toxin‐producing E. coli (STEC) strains in fermented goat's milk

The ability of goat's milk fermented with a Lactobacillus plantarum strain B411, and in combination with commercial starter culture, to inhibit acid‐adapted (AA) and non‐acid‐adapted (NAA) environmental non‐O157 STEC strains was investigated. Acid‐adapted and NAA non‐O157 STEC strains were not inhibited in the L. plantarum‐fermented goat's milk, while the goat's milk fermented with the combination of L. plantarum and starter culture inhibited AA more than NAA non‐O157 STEC strains. Environmental acid‐tolerant non‐O157 STEC strains were not inhibited by L. plantarum, starter culture or combination of starter culture with L. plantarum unless they were subjected to prior acid adaptation such as backslopping.     

In vitro characterisation of probiotic properties of Enterococcus faecium and Enterococcus durans strains isolated from raw milk and traditional dairy products

In this study, some probiotic characteristics such as antimicrobial activity, vancomycin resistance, growth ability at pH, resistance to bile salts, bile salt deconjugation and hydrophobicity of 30 Enterococcus faecium and Enterococcus durans strains isolated and identified from raw milk and various dairy products were investigated. According to the study results, antimicrobial activity profiling, pH and bile salt resistance and bile salt deconjugation ability of Enterococcus strains varied depending on the species and strains and all the strains showed resistance to the tested bile salt concentrations. It was concluded that the E. faecium and E. durans strains tested showed probiotic characteristics and have the potential to be used in food production.     

Phytate dephosphorylation by Lactobacillus pentosus CFR3

Studies on phytate‐degrading enzymes from lactobacilli are scarce, despite its potential in improving the nutritional quality of plant‐based foods. Therefore, the current investigation deals with the phytate‐degrading enzyme produced by a native Lactobacillus pentosus strain. Phytase activity was highest towards the end of the exponential phase. Activity increased in the presence of maltose (381.1%) compared with glucose. The presence of phytate in the media stimulated the enzyme production. The enzyme of interest was a 70 kDa protein with a pH and temperature optima of 5.0 and 55–60 °C, respectively. It retained 46% of activity after exposure to 70 °C for 20 min and also showed broad substrate specificity. It was completely inhibited by Hg²⁺, Fe²⁺ and PMSF while being activated by Co²⁺. This report is the first to show dephytinisation of autoclaved finger millet flour either by fermentation with L. pentosus or by treatment with the corresponding cell‐free extract.     

Characterisation of the technological behaviour of mixtures of mesophilic lactic acid bacteria isolated from traditional cheeses made of raw milk without added starters

In this work, the technological behaviour in milk of a set of Lactococcus lactis strains, alone or in combination with strains of Leuconostoc spp. and Lactobacillus spp. isolated from traditional, raw milk cheeses made without commercial starters, was investigated. Small, mixture‐specific differences during milk fermentation were recorded for growth, milk acidification and production of organic acids, volatile compounds, free amino acids and biogenic amines. Four combinations appropriate for use as dairy starters were tested in pilot‐scale cheese trials. Two mixtures produced cheeses of high flavour and taste quality; these could be confidently used as starter cultures.     

Optimisation of fermentation variables for conjugated linoleic acid bioconversion by Lactobacillus fermentum DDHI27 in modified skim milk

Effects of fermentation variables on conjugated linoleic acids (CLAs) biosynthesis of Lactobacillus fermentum DDHI27 in modified skim milk were evaluated. A total of 0.5 mg/mL was found to be the optimum linoleic acid concentration for maximum CLA production and this level was used in utilised for all successive experiments. The highest production of CLA isomers was detected at pH 6.0 when compared to other pH levels. Maximum biosynthesis of CLA isomers occurred during stationary growth (48 h) phase at all pH values tested. Validation of CLA isomers produced in selected samples was made by GC‐MS. These results indicate that these parameters strongly influence the CLA production capabilities of the strain.     

Robust PCR‐based method for quantification of bovine milk in cheeses made from caprine and ovine milk

To prevent fraud and enhance quality assurance, credible analysis of dairy products is crucial. A common problem is the addition of cheaper bovine milk to caprine and/or ovine dairy products and when not declared addition of bovine milk constitutes fraud. The aim was to develop a rapid, robust and sensitive method for the identification of adulteration of caprine and/or ovine cheeses with bovine milk. New quantitative real‐time polymerase (qPCR) assays were designed for the specific determination of bovine DNA (Cow1) and bovine, caprine and ovine DNA (BoCaOv). These were applied to 17 samples of caprine cheese and 24 of ovine cheese. Results showed that 17% (7/41) of these cheeses contained >5% bovine milk. As bovine milk was not declared as an ingredient in any of the samples, this represents adulteration. Other cheeses that contained detectable bovine milk at ≤5% (22%; 5/41) might pose a health risk to people allergic to bovine milk.     

Incidence and characterisation of aerobic spore‐forming bacteria originating from dairy milk in Tunisia

The purpose of this study was to evaluate the incidence and characterisation of aerobic spore‐forming bacteria originating from dairy milk in Tunisia. The distribution of Bacillus species in raw milk, pasteurised milk and UHT milk were 47.5%, 27.5% and 25%, respectively. Seven Bacillus species, including Bacillus pumilus (10%), Bacillus subtilis (12.5%), Brevibacillus brevis (10%), Bacillus cereus (22.5%), Bacillus sphaericus (7.5%), Bacillus licheniformis (12.5%) and Bacillus sporothermodurans (25%) were identified in different milk samples. Bacillus cereus was predominant in raw and pasteurised milk. Although B. sporothermodurans was the predominant sporogenous micro‐organism in UHT milk, B. cereus, B. sphaericus and B. licheniformis were also present. This study showed that there is a high degree of diversity, both phenotypic and genotypic, among Bacillus isolates from Tunisian milk and the persistence of spoilage risk in UHT milk.     

Production of a whey‐based functional beverage supplemented with soy isoflavones and phytosterols

Reconstituted whey beverages were prepared from whey powder by adding either soy isoflavones or phytosterols as functional compounds (at levels of 0%, 0.25%, 0.50% or 1.0% w/v) and probiotic bacteria (Lactobacillus acidophilus LA‐5 or Lactobacillus casei LBC‐81). The addition of nutraceuticals did not change the basic composition of the products. However, a time‐dependent increase in sedimentation/phase separation and acidity of fermented functional beverages was observed. Samples supplemented with phytosterols were more preferred by the panel group than the samples supplemented with isoflavones, and no considerable differences were noted between the control and phytosterol‐added samples in terms of overall perception.     

Lactobacillus plantarum and Lactobacillus fermentum alone or in combination regulate intestinal flora composition and systemic immunity to alleviate obesity syndrome in high‐fat diet rat

Relationship between intestinal flora and obesity has aroused great interest. The probiotic effects of Lactobacillus plantarum (LP) and Lactobacillus fermentum (LF) have been documented extensively. This study aimed to explore the effects of LP and LF alone or in combination on lipid‐lowering effects of the high‐fat diet rat via intestinal flora modulation and systemic immunity. The rats in high‐fat diet plus LP (LP 10⁸ cfu day^?1) showed significantly lower IL‐6 and endotoxin (ET) content, increased the number of Bifidobacterium and Lactobacillus and decreased the liver steatosis and fat vehicle sizes. The Lactobacillus LP and LF in combination can regulate intestinal flora and systemic immune function in rats with high‐fat diet. It provides the foundation for the further development and application of multiple Lactobacillus strain in controlling obesity‐related syndrome.     

Comparison of buffalo cottage cheese made from aqueous extract of Withania coagulans with commercial calf rennet

An aqueous extract of Withania coagulans was used to prepare cottage cheese from buffalo milk and its quality attributes were compared with cheese made from commercial rennet. Both cheeses contain satisfactory ranges of 49.6–54.7% moisture, 21.3–24.3% fat and 21.4–23.6% protein. The type of coagulant had no significant effect on acidity, protein and ash contents of both the cheeses. W. coagulans cheese showed a significantly (P < 0.05%) higher pH and moisture contents. Similarly, no marked differences were observed in their organoleptic evaluation, actual and theoretical yield. These results supported the fact that W. coagulans is a promising rennet substitute for cottage cheesemaking.     

Development of fermented Hericium erinaceus juice with high content of L‐glutamine and L‐glutamic acid

Fermented plant beverages (FPB) with a high content of desirable principle components are served as functional foods from several years. Hericium erinaceus is famous for its antimicrobial, antioxidant, antihypertensive and antidiabetic nature. Accordingly, the current study was aimed to produce fermented H. erinaceus juice with a high content of L‐glutamine (Gln) and L‐glutamic acid (GA) through lactic acid bacteria (LAB) isolated from fermented Thai foods. LAB isolates were screened and identified the potent protease‐producing bacteria Enterococcus faecalis (G414/1) that facilitate the production of Gln and GA through protein hydrolysis. Box–Behnken design (BBD) and response surface methodology (RSM) were adapted for the optimisation of conditions for the increased production of Gln and GA during fermentation of H. erinaceus. We succeeded with an optimum concentration of cofactor (CaCl₂), pH and temperature for improved protease activity and subsequent Gln and GA production. The ability of isolated E. faecalis strain to produce Gln and GA was demonstrated in this study. Further, upstream processes like strain improvement and media optimisation will direct the way to produce enriched H. erinaceus based FPB.     

The prevention and removal of biofilm formation of Staphylococcus aureus strains isolated from raw milk samples by citric acid treatments

In this study, the antibiofilm activity of citric acid treatment on Staphylococcus aureus strains isolated from raw milk samples was evaluated. For this purpose, the prevention and removal of biofilm formation of S. aureus strains by citric acid treatments (2% and 10%) for 20 min were investigated for comparison with peracetic acid treatment (0.3%) on both microtitration plate and stainless steel coupons. The results indicated that the prevention and removal of biofilm formation and the numbers of prevented or removed S. aureus strains using citric acid treatments were observed to be higher than those using peracetic acid treatment on both surfaces. The prevention and removal of biofilm formation were substantially higher when the concentration of citric acid treatment increased from 2% to 10% and the stainless coupons were used. The results show that citric acid can be used as an alternative disinfectant in controlling biofilm formation in the dairy industry.     

Selection and analysis of bacteriophage‐insensitive mutants of Streptococcus thermophilus isolated in Ukraine

Bacteriophage‐insensitive Streptococcus thermophilus mutants (BIMs) were obtained by treating the phage‐sensitive industrial strains with virulent phages. Five BIMs acquired resistance to S. thermophilus phages of two (cos and pac) main groups selected at Ukrainian dairy processing enterprises. In addition, the valuable biotechnological properties of BIMs were characterised. During fermentation, they formed fermented milk curds with a homogeneous, dense consistency, with pleasant taste and flavour. The BIMs were identified as S. thermophilus by phenotypic and species‐specific PCR methods. The BIMs could be used as starters to stabilise the fermentation process under phage infection conditions.     

Probiotic properties of ice creams produced with dietary fibres from by‐products of the food industry

The objective of this study was to investigate the effects of adding dietary fibre‐rich by‐products to probiotic ice creams. For this purpose, fruit (grape, apricot, apple)‐ and grain (rice, corn, sunflower, barley)‐based by‐products were added to ice cream. The viability of Lactobacillus acidophilus (ATCC 4357D‐5) and Bifidobacterium animalis subsp. lactis (ATCC 27536) was determined with microbial analyses at 1, 15, 30 and 60 days of storage. In conclusion, it was shown that dietary fibre‐rich by‐products could be used in ice cream with improved survival of the probiotic strains without any adverse effects on the physicochemical, microbiological and sensory properties of the ice cream.     

Optimising detection of acidification kinetics diversity in Lactococcus lactis subsp. lactis using SDS‐PAGE protein fingerprinting as screening method

Cell‐free extracts from 157 Lactococcus lactis strains isolated from Artisan cheese were screened by protein fingerprinting previous to their technological characterisation. The strains were classified according to their electrophoretic patterns into five groups. A set of strains representing the different clusters were selected to study their acidifying activity in milk. Time and rate feature points, as well as the shape of the acidification curves, resulted in six different fermentation kinetics, mostly consistent with the electrophoretic groups. Thus, selection of native strains as starter cultures based on their acidifying activity could be optimised by protein fingerprinting.     

Anti‐inflammatory and cytotoxic effects of ginseng extract bioconverted by Leuconostoc mesenteroides KCCM 12010P isolated from kimchi

A bioconversion technique using microorganisms has been applied to ginseng to increase content of bioactive ginsenoside and biofunctionality such as anticancer, anti‐obesity and antioxidant activities. The objective of this study was to screen lactic acid bacteria for bioconversion of ginsenosides and to evaluate anti‐inflammatory and cytotoxic effects of bioconverted ginseng extract. Strains isolated from kimchi were screened for their β‐glucosidase activities using esculin agar. Selected strain was identified based on 16S rRNA sequencing and carbohydrate fermentation. During ginseng fermentation, viable cell number and pH were determined. Bioconverted ginsenosides were analysed by HPLC. Anti‐inflammatory effects were evaluated using RAW 264.7 cells, and cytotoxic effects were determined by MTT assay. Among 166 isolates screened, Leuconostoc mesenteroides was selected for ginseng bioconversion, as it showed a higher β‐glucosidase activity and viable cell number than any of the other tested strains. After fermentation for 2 days, viable cell number was 8.8 log CFU mL^?1 and final pH was 4.8. Ginsenoside Rb₂ was bioconverted into ginsenoside Rg₃ (Rb₂ → Rd → Rg₃) by L. mesenteroides. The nitric oxide contents of 2‐day‐fermented extract decreased by as much as 25%, compared to a non‐fermented extract. The cell viabilities of HepG2, HT‐29, HeLa and LoVo treated with fermented ginseng extract also decreased by 49.7%, 20.2%, 21.0% and 8.7%, respectively, compared to those of control cells treated with non‐fermented extract. Ginseng extract bioconverted by L. mesenteroides showed anti‐inflammatory and anticancer effects. Therefore, bioconverted ginseng extract might have applications in the pharmaceutical and/or functional food industry.