Probiotic Lactobacilli in fermented dairy products: selective detection, enumeration and identification scheme

A selection of 36 commercial probiotic fermented dairy products from UK and Europe markets were evaluated for the numbers, types, and viability of Lactobacillus strains against the stated information on their packages. A comparative study was carried out on selectivity of MRS-Clindamycin, MRS-Sorbitol, and MRS-IM Maltose, to select the right medium for enumeration of probiotic Lactobacillus. Based on selectivity of medium for recovery of the targeted lactobacilli, and also simplicity of preparation, MRS-Clindamycin was chosen as the best medium for enumeration of probiotic Lactobacillus in fermented milks. The results of enumeration of lactobacilli showed that 22 out of a total 36 tested products contained more than 106 colony-forming units/g at the end of their shelf life, which comply with the recommended minimum therapeutic level for probiotics. Rep-PCR using primer GTG-5 was applied for initial discrimination of isolated strains, and isolates, which presented different band profile, were placed in different groups. The isolated Lactobacillus spp. were identified mainly as Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus paracasei by analysis of partial sequences of the 16S ribosomal RNA and rpoA genes

Antimicrobial resistance of lactic acid bacteria from Nono, a naturally fermented milk product

Background: Antimicrobial resistance (AMR) is one of the biggest threats to public health. The food chain has been recognised as a vehicle for transmitting AMR bacteria. However, information about resistant strains isolated from African traditional fermented foods remains limited. Nono is a traditional, naturally fermented milk product consumed by many pastoral communities across West Africa. The main aim of this study was to investigate and determine the AMR patterns of lactic acid bacteria (LAB) involved in the traditional fermentation of milk for Nono production, and the presence of transferable AMR determinants. Methods: One hundred (100) LAB isolates from Nono identified in a previous study as Limosilactobacillus fermentum, Lactobacillus delbrueckii, Streptococcus thermophilus, Streptococcus infantarius, Lentilactobacillus senioris, Leuconostoc pseudomesenteriodes, and Enterococcus thailandicus were investigated. The minimum inhibitory concentration (MIC) was determined for 18 antimicrobials using the micro-broth dilution method. In addition, LAB isolates were screened for 28 antimicrobial resistance genes using PCR. The ability of LAB isolates to transfer tetracycline and streptomycin resistance genes to Enterococcus faecalis was also investigated. Results: The experiments revealed variable antimicrobial susceptibility according to the LAB isolate and the antimicrobial tested. The tetracycline resistance genes tet(S) and tet(M) were detected in isolates Ent. thailandicus 52 and S. infantarius 10. Additionally, aad(E) encoding resistance to streptomycin was detected in Ent. thailandicus 52. The conjugation experiments suggested that the tet(S) and aad(E) genes were transferable in vitro from isolate Ent. thailandicus 52 to Ent. faecalis JH2-2. Significance and Impact: Traditional fermented foods play a significant role in the diet of millions of people in Africa, yet their contribution to the burden of AMR is largely unknown. This study highlights that LAB involved in traditionally fermented foods could be potential reservoirs of AMR. It also underscores the relevant safety issues of Ent. thailandicus 52 and S. infantarius 10 for use as starter cultures as they carry transferable AMR genes. Starter cultures are an essential aspect of improving the safety and quality attributes of African fermented foods. However, AMR monitoring is an important safety aspect in the selection of starter cultures for improving traditional fermentation technologies

Identification and characterisation of the lactic acid bacteria associated with the traditional fermentation of dairy fermented product

The aim of this research was to identify the key lactic acid bacteria associated with the fermentation of dairy traditional fermented products for developing starter cultures for controlled fermentation. A total of 100 lactic acid bacteria (LAB) were isolated from dairy traditional fermented products. Samples were obtained from eight producers in the South East of Nigeria. Isolates were identified by phenotypic and genotypic techniques including rep-PCR genotyping and sequencing of the 16S rRNA, pheS and rpoA genes. Isolates were characterised for antimicrobial activity against foodborne pathogens, exopolysaccharide (EPS) production and survival at low pH and in the presence of bile salts. All isolates clustered into 11 distinct rep-PCR groups and were identified as Lactobacillus fermentum (40%), Lactobacillus delbrueckii (23%), Streptococcus thermophilus (22%), Streptococcus infantarius (10%), Lactobacillus senioris (2%), Leuconostoc pseudomesenteriodes (2%) and Enterococcus thailandicus (1%). Lactobacillus fermentum showed a broad spectrum antimicrobial activity and survival at low pH, while Lactobacillus delbrueckii was able to tolerate low pH and produce EPS. All isolates survived in vitro exposure to 1% (w/v) bile salts over a 3-h period. L. fermentum, L. delbrueckii and S. thermophilus could be used to simulate the fermentation of dairy traditional fermented products

Nanoencapsulation of oregano essential oil using cellulose nanocrystals extracted from hazelnut shell to enhance shelf life of fruits: case study: pears

This study aimed to investigate the potential application of cellulose nanocrystals (CNCs) extracted from an agricultural waste for encapsulation of oregano essential oil (OEO) and subsequently their use for coating to improve the shelf life of pears as a model. By hydrolyzing hazelnut shell cellulose under the optimum conditions, high crystalline CNCs with a zeta potential of -67.8 ± 4.4 mV and a diameter of 157 ± 10 nm were produced. Different concentrations of OEO (10-50 % w/w) were incorporated into CNCs and characterized using FTIR, XRD, SEM and TEM. OEO containing 50 % CNC with the highest EE and LC was selected for coating. Pears were coated with gluten containing 0.5, 1.5 and 2 % encapsulated OEO (EOEO) and pure OEO and stored for 28 days. Physicochemical, microbial and sensory properties of the pears were examined. Microbial analysis showed that EOEO2% was more effective in controlling microbial growth than controls and pure OEO, and a 1.09 Log reduction in bacterial count was recorded on day 28 of storage when compared to control. It was concluded that CNCs produced from an agricultural waste and loaded on an essential oil could be used to extend the shelf life of pear and potentially other fruits

Pickering emulsions stabilized by cellulose nanocrystals extracted from hazelnut shells: production and stability under different harsh conditions

Cellulose nanocrystals (CNCs) are biodegradable particles that have emerged as promising stabilizers for Pickering emulsions. This study investigated the effectiveness of CNCs in forming the Pickering emulsion from hazelnut shells (HS), an agricultural waste. Following the alkaline and bleaching treatments applied to HS, CNCs were obtained from treated hazelnut shell with acid hydrolysis. The physicochemical characteristics of CNCs were investigated using dynamic light scattering, XRD, FTIR, SEM, and TEM. A high crystalline (69.6 %) CNCs with a spherical shape were obtained. Contact angle and interfacial tension tests were conducted and showed that CNCs had amphiphilic nature. Pickering emulsions were investigated for their size, zeta potential, and stability under varying CNC concentrations. The results showed that when CNCs concentration increased from 0.5 to 2.0 wt%, droplet diameter decreased approximately 1.8 times and zeta potential increased. Creaming was not observed during 28 days of storage in a concentration of 2.0 wt% CNCs. The CNC stabilized emulsions exhibited high stability within a range of pH, temperatures, and salt concentrations. This study demonstrated that CNCs extracted from HS as environmentally friendly and cost-effective materials, could serve as a new stabilizer for Pickering emulsions especially for high temperature and low pH sensitive products such as mayonnaise

Lactic microflora present in Liqvan Ewes\u27 milk cheese

This study aimed to isolate and characterize Lactic Acid Bacteria (LAB) in Liqvan Ewes\u27 milk cheese. A total of 117 Lactic Acid Bacteria were isolated and identified phenotypically. They belonged to 4 genera and 17 species. The dominant LAB found in Liqvan cheese were from the genus Lactobacillus (75.21%) consisted of 70.08% facultatively heterofermentative and 5.12% obligately heterofermentative lactobacillus species. Other isolates were classified as Pediococci (5.12%), Enterococci (5.98%), and Leuconostocs (13.67%). Lb. paracasei subsp. paracasei was the predominant species accounted for 36.75%. Likewise, predominant species of each genus were Lb. paracasei subsp. paracasei, P. pentosaceus, E. faecalis, and Leu. lactis. The preponderance of isolates (86.32%) was referred to be as members of Non Starter Lactic Acid Bacteria (NSLAB)

Development of shelf life kinetic model for fresh rainbow trout (Oncorhynchus mykiss) fillets stored under modified atmosphere packaging

The sensory, chemical (based on the thiobarbituric acid, total volatile basic nitrogen and trimethylamine), and microbial quality (based on the total viable count and lactic acid bacteria count) of the rainbow trout stored under modified atmosphere packaging (MAP) conditions was evaluated. Four different gas combinations, including P (80% CO , 10% N , 10% O ), P (60% CO , 20% N , 20% O ), P (60% CO , 40% N , 0% O ), and P (40% CO , 30% N , 30% O ), were used. Also, the fish packages were stored at four constant temperatures (including 0, 5, 10, and 15 °C) for 12 days. The absence of oxygen in P and high concentration of carbon dioxide in P extended the shelf life by delaying the chemical, microbial, and sensory spoilage. Over the storage time of trout fillets in MAP, the rate of chemical reactions significantly increased while the sensory scores decreased. Based on the Arrhenius kinetic modeling for the spoilage reactions of the sensory (total acceptance) and chemical (total volatile basic nitrogen) indices, the shelf life was extended for P and succeedingly, for P packaging

Impact of native Lactobacillus paracasei subsp. paracasei and Pediococcus spp. as adjunct cultures on sensory quality of Iranian white brined cheese

Paired wild-type cultures consisting of a Lactobacillus paracasei subsp. paracasei (three strains) or Pediococcus pentosaceus (one strain) and a Pediococcus inopinatus (five strains) were used as adjunct cultures in the production of Iranian white brined cheese. After 8weeks of ripening, adjunct-treated cheeses produced by L. paracasei subsp. paracasei and P. inopinatus received significantly higher scores for flavour/taste, aroma, texture and overall preference than those produced by P. pentosaceus and P. inopinatus as well as the control cheese (P\u3c0.05). In conclusion, a greater improvement of sensory quality of cheeses was strongly associated with the presence of L. paracasei subsp. paracasei rather than pediococci. © 2011 Society of Dairy Technology

Impact of native Lactobacillus paracasei subsp. paracasei and Pediococcus spp. as adjunct cultures on sensory quality of Iranian white brined cheese

Paired wild-type cultures consisting of a Lactobacillus paracasei subsp. paracasei (three strains) or Pediococcus pentosaceus (one strain) and a Pediococcus inopinatus (five strains) were used as adjunct cultures in the production of Iranian white brined cheese. After 8weeks of ripening, adjunct-treated cheeses produced by L. paracasei subsp. paracasei and P. inopinatus received significantly higher scores for flavour/taste, aroma, texture and overall preference than those produced by P. pentosaceus and P. inopinatus as well as the control cheese (P\u3c0.05). In conclusion, a greater improvement of sensory quality of cheeses was strongly associated with the presence of L. paracasei subsp. paracasei rather than pediococci. © 2011 Society of Dairy Technology

Kharameh cohort study (KHCS) on non-communicable diseases and preliminary findings of 3-year follow-up

Purpose The Kharameh cohort study (KHCS) is one branch of the ‘Prospective Epidemiological Research Studies in Iran’, located in the south of Iran. The enrolment phase of KHCS spanned from April 2015 to March 2017, during which urban and rural residents of Kharameh were enrolled in the study. KHCS aims to investigate the incidence of non-communicable diseases (NCDs) such as hypertension, diabetes mellitus, cardiovascular diseases and cancer, and its related risk factors in a 15-year follow-up.Participants KHCS was designed to recruit 10 000 individuals aged 40–70 years old from both urban and rural areas of Kharameh. Thus, a total of 10 800 individuals aged 40–70 years of age were invited and, finally, 10 663 subjects were accepted to participate, with a participation rate of 98.7%.Findings to date Of the 10 663 participants, 5944 (55.7%) were women, and 6801 (63.7%) were rural residents. The mean age of the participants was 51.9±8.2 years. 41.8% of the participants were aged 40–49, 35.2% were aged 50–59 and the remaining 23% were 60–70 years old. Until March 2020 (first 3 years of follow-up), the total number of patients diagnosed with NCDs was 1565. Hypertension, type 2 diabetes and acute ischaemic heart disease were the most common NCDs. Furthermore, the total number of deaths during the first 3 years of follow-up was 312, with cardiovascular diseases (38.7%) as the most common cause of death, followed by cerebrovascular diseases (11.8%) and cancer (16.2%).Future plans The remaining 12 years of follow-up will inevitably shed light on the genetic, lifestyle/socioeconomic status, and environmental risk and protective factors of NCDs