A promising innovative technique for mycotoxin detoxification from beverages using biofilms of lactic acid bacteria

This study assessed the removal of aflatoxin M₁ (AFM₁) and ochratoxin A (OTA) from artificially contaminated whole UHT milk and red grape juice, respectively, using biofilms from Lactobacillus rhamnosus GG. Using ELISA, the level of AFM₁ and OTA removal from beverages was determined depending on various factors. Biofilms of various ages demonstrated varying degrees of AFM₁ removal capacity from phosphate-buffered saline (PBS). Different levels of AFM₁ contaminated whole UHT milk (0.1, 0.2, and 1 μg/L) and OTA contaminated red grape juice (2 and 4 μg/L) were tested in the detoxification process. The binding ability of mycotoxins was improved by increasing the biofilm surface area up to 70 cm². L. rhamnosus GG biofilm was effective in removing mycotoxins within a short contact time ranging from 1 to 10 min. The proportion of bound AFM₁ and OTA by L. rhamnosus GG biofilm was 64.6 and 98.3% respectively. A new machine has been proposed and used as a trial for detoxication purposes which would be a promising application in liquid food industries.     

Quality characteristics of kefir as a carrier for probiotic Lactobacillus rhamnosus GG

Kefir was prepared using kefir grains of different origins (US, Australia and India) and starter culture. The sensory scores for kefir made using starter culture and US kefir grains were significantly higher than for the other samples (P < 0.05). The index of viscosity was significantly higher (P < 0.05) in kefir prepared using Indian kefir grains. Shear stress–shear rate plots indicated yield stress in all kefirs. All samples exhibited shear‐thinning behaviour. The average count of Lactobacillus rhamnosus GG in kefir after incubation was 7.09 log CFU/g. No significant difference (P > 0.05) was observed in quality characteristics in kefir after the addition of LGG, indicating that it could be a potential probiotic carrier.     

Formation and dispersal of biofilms in dairy substrates

The formation and dispersion of biofilms in the dairy industry is a problem because it increases cross‐contamination, affecting the shelf life of the products and their safety. The objective of this study was to evaluate the influence of different dairy substrates (cows’ milk and whey protein) on the formation and dispersion of Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus in two biofilm systems (mono‐species and multi‐species) on stainless steel at 25 °C. The dominant behaviour of E. faecalis occurred in most of the tests on mono‐species and multi‐species biofilms. A greater dispersion of biofilm cells was observed in skimmed milk.     

Determination of the relationship between oxalate degradation and exopolysaccharide production by different Lactobacillus probiotic strains

The aim of this study was to evaluate the protective effects of exopolysaccharide (EPS) production on resistance to gastrointestinal digestive conditions and oxalate by probiotic strains of the species Lactobacillus rhamnosus, Lactobacillus fermentum and Lactobacillus brevis. The oxalate‐degrading ability of the strains was determined using an enzymatic assay. The correlation between oxalate degradation rate and EPS production was not significant (P > 0.05); however, the high‐EPS‐producing L. fermentumIP5 and L. brevisYG7 strains showed high oxalate‐degrading activity, whereas the low‐EPS‐producing strain L. fermentumBP5 demonstrated low oxalate‐degrading activity. The present findings suggest that dietary supplementation with the probiotic strain L. fermentumIP5 could be a promising strategy for the prevention of oxalate stone disease.     

Synergistic effect between Helichrysum italicum essential oil and cold nitrogen plasma against Staphylococcus aureus biofilms on different food‐contact surfaces

Staphylococcus aureus is the most common pathogen in human, and the most diseases produced by S. aureus are associated with biofilms. Helichrysum italicum essential oil (EO), as a natural and safe spice, was employed to disperse S. aureus biofilm by cold nitrogen plasma (CNP) assist. After S. aureus biofilm formation on food container surfaces, they were exposed to CNP and then treated with Helichrysum italicumEO for biofilm dispersion. The population of S. aureus biofilm was approximately reduced by 2 logs after individual treatment of 0.5 mg mL^?1 Helichrysum italicumEO or 400 W CNP. Interestingly, the combined treatment of Helichrysum italicumEO (0.5 mg mL^?1, 40 min) and CNP (400 W, 1 min) reduced the S. aureus viable count in biofilm below 2 logs CFU per cm² after 1‐day storage. Therefore, the synergetic treatment holds great promise to improve the current treatment systems of bacterial contamination on different food‐contact surfaces.     

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.     

A new synbiotic dairy food containing lactobionic acid and Lactobacillus casei

As well as its beneficial health properties, the incorporation of the prebiotic lactobionic acid (LBA) in fermented dairy products can provide a technological advantage due to its gelling capacities. This study aimed to develop a new functional dairy product containing LBA synthesised within the process itself by the bacterium Pseudomonas taetrolens. A probiotic Lactobacillus casei strain was introduced through a sequential fermentation system. After incubation, in the case of the most effective experimental procedure, a synbiotic fermented milk with 30 g/L of prebiotic LBA was obtained, together with an active L. casei population of 10⁹ cfu/mL and <1% lactose content.     

The effects of ratio of cow's milk to soymilk,probiotic strain and fruit concentrate on qualitative aspects of probiotic flavoured fermented drinks

The effects of proportion of cow's milk to soymilk (100:0, 75:25, 50:50, 25:75, 0:100), probiotic bacteria (Lactobacillus acidophilus LA‐5 or Lactobacillus casei L‐01) and natural fruit concentrates (strawberry, apricot, peach and pear) on quality characteristics of soy‐based probiotic drink were investigated. The parameters were analysed at the end of fermentation and during 21 days of storage at 5 ^°C. The highest viability was observed when the equal proportion of cow's milk and soymilk and L. casei was used (50:50‐CY). During chilled storage, the flavouring apricot had the highest stimulatory effect on the survival of L. casei in 50:50 treatment. In general, the treatment 50:50‐CY was realised as the best one overall.     

Effects of Zataria multiflora boiss essential oil,ultraviolet radiation and their combination on Listeria monocytogenes biofilm in a simulated industrial model

The objective of this study was to investigate the inhibitory effect of Zataria multiflora boiss essential oils (ZEOs), ultraviolet (UV) radiation and their combination against Listeria monocytogenes biofilm in a simulated industrial model (SIM). The effect of minimal inhibitory concentration (MIC) and sub‐MIC concentration of ZEOs, different contact time of UV and their combination was evaluated in a SIM on 6‐ and 12‐day‐old L. monocytogenes biofilm. In a SIM, 0.3% ZEOs were adequate to completely eliminate 6‐ and 12‐day‐old biofilm grown on stainless steel coupons. The population of viable L. monocytogenes biofilm cells under a 15‐ to 45‐min contact time of UV treatment declined significantly at 6‐ and 12‐day‐old biofilm. The combined effect of ZEO and UV showed antagonist effects. These findings indicated that in the single use, ZEO and UV revealed a suitable antilisteria biofilm activity, while combining them is not a promising method to remove listeria biofilms from stainless steel surfaces.     

Development of vacuum‐dried probiotic milk powder with Bacillus coagulans

The present study explored the possibilities of using Bacillus coagulans as a probiotic culture in vacuum‐dried milk powder. The operational drying temperature at 63 ± 2 °C under 0.7 kg/cm² pressure emerged as the best temperature at which to prepare dried milk powder within 4.5 h with a mean (±SEM) Bacillus coagulans B37 spore count of 8.78 ± 0.03 log cfu/g and moisture content of 4.82 ± 0.12%. The total spore counts in vacuum‐dried milk powder did not change (P > 0.10) at storage temperatures of 7 °C, 37 °C or 45 °C over a three‐month period.     

Comparative analysis of the fermentation performance of high‐quality milk beer strains (Kluyveromyces marxianus) and optimisation of medium formula for high‐density fermentation

Milk beer is a new type of dairy beverage in China and increasingly popular with consumers. The strain FXJ1 isolated in our laboratory was an excellent strain for the production of milk beer with alcohol content of 0.48%. Our research verified that the strain FXJ1 was superior to the commercial strain MJ for milk beer production and got the optimal medium formula (67.37 g/L sucrose, 29.7 g/L yeast extract, 15.61 g/L corn steep liquor, 4.13 g/L KH₂PO₄ and 0.3 g/L MgSO₄) which allowed the biomass production of strain FXJ1 to achieve 8.88 ± 0.08 g/L and increase 2.94‐fold as compared with yeast extract peptone dextrose base medium.     

Occurrence and antibiotic resistance of Escherichia coli,Staphylococcus aureus and Bacillus cereus in raw milk and dairy products in Turkey

In this survey, 150 samples of raw milk, white cheese and ice cream from three different dairy‐processing plants in Ankara were analysed to find out if they were contaminated with Escherichia coli, Staphylococcus aureus or Bacillus cereus. The highest contamination percentages were found in raw milk samples as follows: B. cereus (90%), E. coli (74%) and S. aureus (56%) followed by cheese (70% B. cereus, 60% E. coli, and 48% S. aureus) and ice cream (56% E. coli, 36% S. aureus and 20% B. cereus). The survey showed that 2% of cheese samples were contaminated with E. coli O157. It was also found that the numbers of S. aureus and E. coli in raw milk, cheese and ice cream samples exceeded the numbers permitted under the Turkish Food Codex (TFC). The number of B. cereus in raw milk, cheese and ice cream samples was lower than the limit given in the TFC standards. The study also showed that E. coli and S. aureus exhibit resistance to ampicillin, penicillin, tetracycline, erythromycin, gentamicin and trimethoprim/sulfamethoxazole. Escherichia coli isolates also showed resistance to chloramphenicol and ciprofloxacin but none of them exhibited resistance to cefotaxime. All S. aureus isolates were found to be susceptible to cefotaxime, chloramphenicol, and ciprofloxacin. Bacillus cereus isolates were found to be resistant to ampicillin, penicillin and trimethoprim/sulfamethoxazole and sensitive to cefotaxime, chloramphenicol, ciprofloxacin erythromycin, gentamicin and tetracycline.     

Viability of Lactobacillus acidophilus in rice bran‐enriched stirred yoghurt and the physicochemical and sensory characteristics of product during refrigerated storage

This study was aimed at investigating the fortification of probiotic yoghurt with rice bran to increase nutritional properties of the product. The different levels of rice bran (0.3%, 0.6%, 0.9% and 1.2%) were incorporated into milk. The yoghurt samples were produced after pasteurisation, addition of starter culture and 1% Lactobacillus acidophilus suspension (6 × 10⁸ CFU mL^?1) and incubation. During sample storage in refrigerator, the viability of L. acidophilus, viscosity and physicochemical and sensory properties of product were investigated. Rice bran significantly increased the viability of L. acidophilus (P < 0.05). In addition, all probiotic yoghurts incorporating rice bran indicated higher viscosity and acidity and lower pH and syneresis compared to plain yoghurts. Furthermore, increments in rice bran incorporation levels resulted in a reduction in consumers' sample preferences. In general, the addition of rice bran at a suitable level could increase L. acidophilus viability and improve quality attributes of yoghurt.     

Bacillus and Paenibacillus species associated with extended shelf life milk during processing and storage

Characterisation of spore formers associated with extended shelf life milk was performed by analysing the bacteriological quality of milk samples collected at various processing stages and during storage. Isolates were identified with MALDI‐TOF‐MS. Milk had spore counts <2 log₁₀ cfu/mL and 4 log₁₀ cfu/mL during processing and storage, respectively. Bacillus pumilus dominated the bacterial population. Bacterial species were inoculated into sterile milk for a shelf life study, and the population change was observed over 42 days at 7 °C. Although the extended shelf life milk process was effective in reducing bacterial counts and species diversity, the presence of Bacillus cereus shows a potential safety problem in extended shelf life milk.     

Potential public health risk due to consumption of contaminated bovine milk with aflatoxin M1 and Coxiella burnetii in the West of Iran

This study aimed to evaluate the probable public health hazard imposed by bovine milk in relation to aflatoxin M1 (AFM1) and Coxiella burnetii in the West of Iran. The assessment of AFM1, using an ELISA test, indicated 62.22% and 21.11% of 45 samples of raw and pasteurised milk were above the permissible content of Codex and Iranian standard levels, respectively. Further, anti‐C. burnetii antibody was detected in 63.04% of bulk tank milk samples, with six samples harbouring the bacterial genome. High AFM1 contamination levels and an endemic pattern of Q fever warrant continuous surveillance programmes in the studied region.     

Lactic acid fermentation of brewer's spent grain hydrolysate by Lactobacillus rhamnosus with yeast extract addition and pH control

Lactic acid (LA) is a versatile chemical with a wide range of applications in food, pharmaceutical, cosmetic, textile and polymer industries. Brewer's spent grain (BSG) is the most abundant brewing by‐product. In this study BSG hydrolysates were used for LA fermentation by Lactobacillus rhamnosus ATCC 7469. The aim of this study was to evaluate the effects of pH control during fermentation, reducing sugar content and yeast extract content in BSG hydrolysate on LA fermentation parameters. The pH control greatly increased reducing sugar utilization, l ‐(+)‐LA content, yield and volumetric productivity. The highest l ‐(+)‐LA yield and volumetric productivity were achieved with the reducing sugar content of 54 g/L. Yeast extract addition significantly increased reducing sugar utilization, l ‐(+)‐LA content, L. rhamnosus cell viability, l ‐(+)‐LA yield and volumetric productivity. The highest l ‐(+)‐LA content (39.38 g/L), L. rhamnosus cell viability (9.67 log CFU/mL), l ‐(+)‐LA yield (91.29%) and volumetric productivity (1.69 g/L/h) were achieved with the reducing sugar content of 54 g/L and yeast extract content of 50 g/L. Copyright © 2017 The Institute of Brewing & Distilling     

Effect of nisin‐producing Lactococcus lactis starter cultures on the inhibition of two pathogens in ripened cheeses

The effect of Lactococcus lactis nisin‐producing strains, isolated from Italian fermented foods, on the survival of two foodborne pathogens namely Listeria monocytogenes and Staphylococcus aureus was investigated in experimental cheese production. One of the three Lactobacillus lactis nisin innoculated as starters, Lactobacillus lactis 41FL1 lowered S. aureus count by 1.73 log colony‐forming units (cfu)/g within the first 3 days, reaching the highest reduction, 3.54 log cfu/g, by the end of ripening period of 60 days. There was no effect on L. monocytogenes. The application of L. lactis 41FL1 as bioprotective culture in controlling S. aureus shows considerable promise.     

Efficacy testing of teat dip solutions used as disinfectants for the dairy industry: Antimicrobial properties

The production of raw milk containing a limited number of bacterial contaminants, which retains its quality during storage, is the major task of the dairy industry. This can only be achieved with adequate regular cleaning and disinfection of the udder, milking equipment, the dairy parlour and animal housing areas. Studies were conducted to assess the efficacy of a range of dairy disinfectants on bacterial species isolated from cow udders as well as reference microbial strains (ATCC). Testing included the assessment of bacterial growth inhibition, biofilm inhibition or bacterial susceptibility to disinfection treatment. Findings show that Lir Analytical chemical disinfectants proved highly successful at inactivating a range of Gram‐positive (Bacillus, Enterococcus, Aeromonas) and Gram‐negative (Escherichia coli, Pseudomonas, Micrococcus) organisms, with up to 99.9% inactivation achieved. Additionally, test chemicals provided significant levels (P < 0.05) of biofilm inhibition for a number of test species. Furthermore, it was found that bacterial isolates from cow udders proved more sensitive to the test chemicals than their reference counterparts.     

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.     

Effect of calcium and vitamin D2 fortification on quality characteristics of dahi

Two levels (500 and 600 ppm) of calcium (calcium phosphate and calcium citrate) along with vitamin D₂ (600 IU/L) were fortified in milk for dahi preparation. pH, water‐holding capacity and syneresis of fortified dahi were not affected significantly (P > 0.05). However, acetaldehyde content decreased and setting time increased upon fortification. Microbial count significantly (P < 0.05) decreased in calcium phosphate‐fortified dahi, whereas no difference was observed in calcium citrate‐fortified dahi. Firmness and viscosity decreased in calcium phosphate‐fortified dahi, whereas it increased in calcium citrate‐fortified dahi as compared to control. All dahi samples showed good sensory acceptability.