Traditional Fermented Milk Research Articles

Characteristics of volatile flavor components in traditional fermented yak milk produced in different ecoregions of the Qinghai-Tibetan plateau

The volatile flavor substances in traditional fermented yak milk samples collected from 5 ecoregions (A: coniferous forests and grasslands of the Qilian Qingdong Mountains; B: alpine grasslands surrounding the lakes in the Qiangtang Plateau; C: alpine shrubs and meadows of the Guoluo-Nagqu Highlands; D: coniferous forests along the alpine valley in East Tibet; E: shrubs and grasslands along the alpine valley in South Tibet) of the Qinghai-Tibetan plateau were comparatively analyzed. The relative percentage composition of volatile flavor substances varied among the different ecoregions. In samples collected from region E, more than 50% of the volatile flavor compounds were esters comprising mainly n-butyl acetate, butyl butyrate, and ethyl octanoate, and a considerable proportion of acetoin was found in samples from regions B and E. Greater proportions of 2-heptanone and 2-nonanone were observed in samples collected from regions A, C, and D compared with regions B and E.

Effect of Lactobacillus casei subsp. casei R-68 Isolated from Dadih on the Procarcinogenic Enzyme Activity and Fecal Microflora Count of Rats Challenged with Pathogenic Bacteria

The human digestive tract is a complex ecosystem that may contain bacteria, yeast, and other microflora, which have harmful and beneficial effects on the host. Species of Lactobacillus and Bifidobacterium are most commonly used as probiotics. Lactobacillus casei subsp. casei R-68 (LCR-68) isolated from dadih, traditional fermented buffalo milk from West Sumatera has the potential to be used as probiotic. The purposes of the present study were to evaluate the ability of strain LCR68 to inhibit the growth of the pathogenic bacteria Listeria monocytogenes FNCC-0156 and Escherichia coli FNCC-19 and reduce the activity of fecal mutagen enzymes in Wistar rats. The in vivo test used 25 male Wistar rats with an average weight of 174 - 176 g. This study consisted of five groups of treatment with five rats of each group. The results show a significant increase in the growth in all groups, although a significantly lower weight gain was observed in rats challenged with Listeria monocytogenes and fed fermented milk LCR-68. The counts of aerobic and anaerobic microbes were the same in all groups. Significantly higher counts of lactic acid bacteria were determined after the application of fermented milk LCR68. Significantly lower counts of Escherichia coli were also observed after the application of fermented milk LCR68. The presence of LCR-68 in fermented milk reduced the activity of β-glucuronidase and β-glucosidase significantly in the feces of Wistar rats. Therefore, the strain R-68 as a probiotic is expected to be able to prevent the formation of procarcinogenic compounds into carcinogens that cause cancer in the digestive tract.

Microbial diversity and volatile profile of traditional fermented yak milk

Previous research reported that fermented yak milk had a diverse microbial composition. For this study, raw yak milk, qula, and fermented yak milk samples were collected from the Aba Tibetan autonomous region of China. The genus and species microbial composition of these samples were analyzed by high-throughput sequencing of 16S rRNA and groEL gene amplicons, and the volatile profile of the samples was quantified by gas chromatography-mass spectrometry. The results indicated variation in abundance of microbiota at the genus level among the fermented yak milk samples, with Lactobacillus as the most abundant genus in the majority of samples, ranging from 41.6 to 98.3%. The volatile profile of the samples varied among those collected from different villages. Correlations between bacterial composition and volatile compounds of the samples were also observed. Lactobacillus displayed a significant correlation with volatile compounds such as benzaldehyde, 2,3-pentanedione, ethanol, and ethyl acetate, whereas the samples with relatively high abundance of Streptococcus and Lactococcus displayed relatively low contents of volatile compounds.

Nutritional quality of milk curd by adding avocado extract (Persea americana, mill) using gombong bamboo (Gigantochloa verticilata)

Curd is a traditional fermented buffalo milk from West Sumatra.Fermentation in curd making occurs spontaneously, meaning thatfermentation occurs naturally without the addition of a starter. This studyaims to determine the nutritional content of cow milk curd with the additionof avocado extract (Persea americana, Mill) various levels using Gombongbamboo (Gigantochloa verticilata).This research was conducted at the Analogy and Physiology Laboratory ofthe Faculty of Agriculture, University of North Sumatra in November 2018-December 2018. The design used in this study was a completelyrandomized design (CRD) with 5 treatments and 4 replications. Theparameters analyzed were Protein, Fat, and pH. The results showed thatcow milk curd with the addition of avocado (Persea americana, Mill)extract various levels using Gombong bamboo (Gigantochloa verticilata)significantly had different effects on the nutritional value of protein, fat andpH. From the nutritional value studied, the highest protein: P1 7.57% withthe addition of avocado fruit extract (Persea americana, Mill) 6%, fataverage: P1 7.08% with the addition of avocado fruit extract (Perseaamericana, Mill) 6%, pH: P4 5.30% with the addition of avocado fruitextract (Persea americana, Mill) 24%.

Use of lactobacilli strains with probiotic potential in traditional fermented milk and their impact on quality and safety related to Listeria monocytogenes

UHT bovine milk (low-fat) was inoculated with a starter culture and one adjunct strain, Lactobacillus plantarum 2035 or Lb. plantarum T571, with probiotic potential, and also with a cocktail mixture of three strains of Listeria monocytogenes at three different initial levels of inoculum and the milk was fermented to pH 4.5. Microbiological, physicochemical, molecular and sensory analyses were performed during storage at 4 and 12 °C. The probiotic samples displayed higher counts of lactic acid bacteria, higher acidity, lower pH and reduced counts of L. monocytogenes, in shorter time period than the control at 4 °C. Molecular analysis verified the presence of the probiotic strains until the end of storage at both temperatures and in adequate amounts; survival of L. monocytogenes strains depended on the treatment. Sensory evaluation showed that the probiotic fermented milks had desirable organoleptic characteristics, similar to the control.

Goat Milk with Different Alpha-s1 Casein Genotype (CSN1S1) Fermented by Selected Lactobacillus paracasei as Potential Functional Food

The characteristics of fermented milk are affected by the type of milk used and the microorganisms involved in the fermentation process. Goat milk has been widely suggested as a possible alternative to cow milk in allergic subjects, because of the high genetic variability in alpha-s1 casein (CSN1S1) content, which is associated with different technological and nutritional properties of milk. The aim of the study was to evaluate the suitability of goat milk with low and high CSN1S1 to produce fermented milk. In addition, the performance as starter of selected Lactobacillus paracasei FS109 strain compared to no-selected L. paracasei strains was investigated. Initially, the selected L. paracasei FS109 strain was tested for adhesion ability to HT-29 and Caco-2 cells and immunomodulation effect. Then, the strain was used to produce fermented milk from goat milk with a low and high casein CSN1S1 genotype. The results indicated that greater acidifying activity was obtained for L. paracasei FS109 after 24 h of fermentation than the other two strains tested independently by the CSN1S1 genotype. L. paracasei FS109 grew well during fermentation, reaching a higher value (>8.5 log CFU/mL). Interestingly, the same strain maintained a high viable population (about 9 log CFU/mL) during the 30-day cold storage of the product. The present study shows for the first time the suitability of the goat milk with low CSN1S1 genotypes to produce fermented milk and highlight the importance of strain selection in determination of technological and beneficial traits. Combining goat milk with low CSN1S1 and selected strains could be a strategy of improving traditional and functional fermented milk market.

Metagenomic analysis of bacterial community composition in Dhanaan: Ethiopian traditional fermented camel milk

This study was conducted to evaluate the safety and bacterial profile of Dhanaan (Ethiopian traditional fermented camel milk). The composition of the microbial community in Dhanaan samples was analysed by a metagenomic approach of 16S rRNA gene amplicon sequencing. Metagenomic profiling identified 87 different bacterial microorganisms (OTUs) in six samples analysed. Although the Dhanaan samples contained various lactic acid bacteria (LAB), they also all contained undesirable microorganisms in large proportions. The following LAB genera were identified: Streptococcus, Lactococcus and Weissella. One Streptococcus species represented by OTU-1 (operational taxonomic unit) was found in all Dhanaan samples and the dominating species in four out of six samples. This common isolate was found to be closely related to S. lutetiensis and S. infantarius. Undesirable microorganisms from genera such as Escherichia, Klebsiella, Enterobacter, Acinetobacter and Clostridium were, however, also frequent, or even dominant in Dhanaan samples. Thus, this calls for a change in the Dahnaan manufacturing practice to an improved and safer production system. Starter cultures suitable for Dhanaan production might be developed from the Streptococcus, Weissella and Lactococcus microorganisms identified in this study. However, further safety evaluation and technological characterization need to be conducted on strains defined by OTU-1, OTU-2, OTU-3, OTU-8 and OTU-35 before they can be used as food grade starter cultures.

Preparation, Bioavailability, and Mechanism of Emerging Activities of Ile-Pro-Pro and Val-Pro-Pro.

Ile-Pro-Pro and Val-Pro-Pro are two most well-known food-derived bioactive peptides, initially identified as inhibitors of angiotensin I-converting enzyme (ACE) from a sample of sour milk. These two peptides were identified in fermented and enzymatic hydrolyzed cow and non-cow (that is, goat, sheep, buffalo, yak, camel, mare, and donkey) milk, as well as sourdough prepared from wheat, rye, and malt. Similar to other bioactive peptides, bioavailability of these peptides is low (about 0.1%), reaching picomolar concentration in human plasma; they showed blood pressure lowering activity in animals and in human, via improved endothelial function, activation of ACE2, and anti-inflammatory property. Emerging bioactivities of these two peptides toward against metabolic syndrome and bone-protection received limited attention, but may open up new applications of these peptides as functional food ingredients. Further studies are warranted to determine the best source as well as to identify novel enzymes (particularly from traditional fermented milk products) to improve the efficiency of production, to characterize possible peptide receptors using a combination of omics technology with molecular methods to understand if these two peptides act as signal-like molecules, to improve their bioavailability, and to explore new applications based on emerging bioactivities.

Metagenomic analysis of bacterial community composition in Dhanaan: Ethiopian traditional fermented camel milk.

This study was conducted to evaluate the safety and bacterial profile of Dhanaan (Ethiopian traditional fermented camel milk). The composition of the microbial community in Dhanaan samples was analysed by a metagenomic approach of 16S rRNA gene amplicon sequencing. Metagenomic profiling identified 87 different bacterial microorganisms (OTUs) in six samples analysed. Although the Dhanaan samples contained various lactic acid bacteria (LAB), they also all contained undesirable microorganisms in large proportions. The following LAB genera were identified: Streptococcus, Lactococcus and Weissella. One Streptococcus species represented by OTU-1 (operational taxonomic unit) was found in all Dhanaan samples and the dominating species in four out of six samples. This common isolate was found to be closely related to S. lutetiensis and S. infantarius. Undesirable microorganisms from genera such as Escherichia, Klebsiella, Enterobacter, Acinetobacter and Clostridium were, however, also frequent, or even dominant in Dhanaan samples. Thus, this calls for a change in the Dahnaan manufacturing practice to an improved and safer production system. Starter cultures suitable for Dhanaan production might be developed from the Streptococcus, Weissella and Lactococcus microorganisms identified in this study. However, further safety evaluation and technological characterization need to be conducted on strains defined by OTU-1, OTU-2, OTU-3, OTU-8 and OTU-35 before they can be used as food grade starter cultures.

Analysis of Health Benefits Conferred by Lactobacillus Species from Kefir.

Lactobacilli are among the most common microorganisms found in kefir; a traditional fermented milk beverage produced locally in many locations around the world. Kefir has been associated with a wide range of purported health benefits; such as antimicrobial activity; cholesterol metabolism; immunomodulation; anti-oxidative effects; anti-diabetic effects; anti-allergenic effects; and tumor suppression. This review critically examines and assesses these claimed benefits and mechanisms with regard to particular Lactobacillus species and/or strains that have been derived from kefir; as well as detailing further potential avenues for experimentation.

Characterization of antifungal metabolites produced by novel lactic acid bacterium and their potential application as food biopreservatives

Fungal growth and mycotoxin production on foods and feeds cause poisoning and serious human diseases that may lead to death. Chemical preservatives and fungicides have negative impacts on both health and environment. In contrast, bio preservatives such as lactic acid bacteria (LAB) are effective, safe, biodegradable and have additional health benefits. Among 23 rod-shaped LAB strains that were isolated from Egyptian traditional fermented milk (Rayeb), strain RM1 showed the highest antifungal potency. Phylogenetic analysis based on complete 16S rRNA gene and unique phenotypic characteristics differentiated strain RM1 from the closely related Lactobacillus species suggesting it represents a novel species, for which the name Lactobacillus sp. RM1 is proposed. The cell-free supernatant (CFS) of Lactobacillus sp. RM1exhibited strong and broad antimicrobial activity against both toxigenic fungi and harmful bacteria. The chemical composition of CFS determined by GC–MS showed a wide variety of antioxidant and antimicrobial compounds. A complete inhibition of both aflatoxins B1 and ochratoxin A production was obtained at a CFS concentration of 15 mg/mL. When the CFS was used to treat wheat grains, the growth mycelia of Aspergillus parasiticus were completely inhibited after 2 weeks of incubation compared with untreated grains, which were covered with a mat of the fungus. The antifungal activity of Lactobacillus sp. RM1 against common toxigenic fungi, and its ability extend the shelf life of wheat grains prove its potential application as a natural preservative for food products.

Microbial Quality and Safety of Traditional Fermented Camel Milk Product Suusac Sampled from Different Regions in North Eastern, Kenya

Aim: The study was carried out to assess the microbial quality and safety of fermented camel milk product (Suusac) from North Eastern Kenya.
 Methodology: Twenty-eight samples (n=28) of Suusac from different areas of the region sold in informal markets at Eastleigh in Nairobi were aseptically collected at the sales points. The quality and safety of the Suusac with reference to selected pathogens namely E. coli, S. aureus, Shigella, and Klebsiella spp was evaluated using the standard analytical methods.
 Results: Escherichia coli were detected in all the samples while Staphylococcus aureus was detected in 63.09% of the samples analyzed. Shigella spp was detected in 88.1% of the samples analyzed and Klebsiella spp was detected in 77.4% of the samples. The mean log10 counts for E. coli, S. aureus, Shigella, and Klebsiella spp were 3.135, 2.576, 2.784 and 3.138, CFUmL-1, respectively. There is a potential public health concern posed by Suusac which is sold for direct consumption due to the presence of the life-threatening bacterial pathogens.
 Conclusion: The Suusac being sold at Eastleigh market in Nairobi from North Eastern Kenya may be responsible for transmission of the pathogens to the consumers. Training on food hygiene, improving production technology, hygienic conditions and implementing the food legislations along the value chain can minimize the risk.

Functional characteristics of lactobacilli from traditional Bulgarian fermented milk products.

After oral administration, probiotic lactobacilli meet a number of protection systems in the human body, such as exposure to gastric, pancreatic, and small intestinal juices. Overcoming these detrimental barriers allows living bacteria to adhere to the intestinal epithelium and permanently colonize the gastrointestinal tract (GIT), providing health benefits to the host. Based on this, the transit tolerance of 25 candidate probiotic lactobacilli from katak, yoghurt, and white-brined and yellow cheese to simulated bile and small intestinal juices of variable pH was investigated. To establish their resistance, in vitro model systems based on modified MRS media and a longer duration of action (up to 24 h of incubation) were designed. Six of the strains studied were found to show strain-specific survival capacity with low viability in conditions simulating stomach acidity and high resistance to bile and intestinal juices. In addition, the adherence capability (autoaggregation and hydrophobicity) of the strains was determined. Obtained results allowed to select Lactobacillus strains with high survival ratios while passing through the GIT and good adherence properties, which make them suitable for the development of new probiotics.

Characterisation of lactic acid bacteria isolated from the Georgian, yoghurt‐like Matsoni

Matsoni is a traditional Caucasian fermented milk product, characterised by a lactic acid bacteria (LAB) microbiota. Objectives of the present study were to isolate and identify the LAB of Matsoni samples collected from various Georgian areas and to study their technological characteristics. About 300 LAB from 71 samples of Matsoni were isolated and characterised. The species most representatives were Lactobacillus delbrueckii, Streptococcus thermophilus and Lactobacillus rhamnosus. This study highlighted a high degree of biodiversity and a specific geographical distribution of the dominant LAB present in artisanal Matsoni. Some strains showed technological features useful to design a multistrain starter culture for Matsoni.

High-Throughput Illumina MiSeq Amplicon Sequencing of Yeast Communities Associated With Indigenous Dairy Products From Republics of Benin and Niger.

Traditional Wagashi cheese and fermented cow milk are among the most popular dairy products appreciated by people from Benin, Niger, and the neighboring region. These products are the main source of protein in the diet of the low-income population in the region. The fermented milk is prepared by spontaneous fermentation without back-slopping. Whereas, the leaf extract of Calotropis procera is used for curdling the milk to prepare the soft Wagashi cheese. The present study aims to provide in-depth analysis of yeast communities associated with these traditional milk products by high-throughput Illumina MiSeq amplicon sequencing of internal transcribed spacer (ITS) region of fungal rRNA genes. A total of 60 samples, 20 samples of fermented milk each from Benin and Niger, and 20 samples of Wagashi cheese from Benin were used for analysis. The metagenomic investigation revealed that Kluyveromyces marxianus, Saccharomyces cerevisiae, Candida parapsilosis, and Sagenomella keratitidis were the predominant yeast species present in the traditional milk products. Furthermore, we noticed a high presence of K. marxianus (61.1% relative abundance) in the Wagashi cheese and S. cerevisiae (28.4% relative abundance) in the fermented milk of Niger. The presence of potential pathogenic yeast C. parapsilosis and S. keratitidis in these African milk products calls for further investigation to assess their safety. The predominant yeast K. marxianus and S. cerevisiae, recognized with generally regarded as safe (GRAS) status, could be further selected as starter culture along with lactic acid bacteria for developing controlled fermentation processes with enhanced product quality and safety.

The art of mabisi production: A traditional fermented milk.

Fermented dairy products can be rich in beneficial microbes and one such product with potential is mabisi. Mabisi is a traditional fermented milk product from Zambia made through spontaneous fermentation of raw milk at ambient temperature using a calabash (gourd), clay pot, plastic or metal container. The fermentation takes about 48 hours after which the product is stirred and ready for consumption. This study was aimed at determining the types of production methods of mabisi and identifying the critical production process parameters. A survey was conducted using interviews and observations to determine the existing production practices/technologies and to capture indigenous knowledge on mabisi production in nine provinces of Zambia. We found seven different production methods which we coined; tonga, thick-tonga, illa, barotse, backslopping, cooked and creamy types. Interestingly, the tonga-type mabisi was produced throughout the country by different ethnic groups. The main process parameters were found to be fermentation time and temperature, type of containers, presence/absence of backslopping, agitation, heating and cooling, removal of whey and addition of raw milk. And further found that mabisi is a versatile product consumed with a wide variety of foods. This basic information is crucial for production process optimisation and microbial communities dynamics studies.

Effects of Fermentative Factors on Biochemical, Microbiological and Sensory Characteristics of Probiotic Iranian Fermented Milk (Doogh)

Background: Doogh is a traditional Iranian fermented milk drink that is currently a very popular product in Iran. In the present study, the combined effects of incubation temperature, type of starter culture, and final pH of fermentation on the viability of two probiotic strains (Lactobacillus acidophilus La-5 (A) and Bifidobacterium lactis Bb-12 (B)) and biochemical and sensory characteristics of probiotic Doogh were investigated. </P><P> Method: Different treatments were prepared with yoghurt starter culture containing probiotics, using reconstituted skimmed milk with 6% of solid nonfat. They were incubated at 38°C or 44°C until pH 4.0 or pH 4.5 and were kept for 21 days at 4°C or 8°C storage temperature. The biochemical properties of treatments were evaluated during fermentation and refrigerated storage. The viable count and sensory attributes of treatments were studied at the end of fermentation and at the end of storage. </P><P> Results: Results showed that the greatest mean pH drop rate, mean acidity increase rate and mean redox potential increase rate and the shortest incubation time were observed in treatments incubated at 44°C with final pH of 4.5. The highest survival of both probiotic strains during storage was related to treatments with fermentation temperature of 38°C and final pH of 4.5. Treatments ABY1-38°C-4.0 had the highest sensorial total acceptance at the end of refrigerated storage. </P><P> Conclusion: It would be concluded that the best treatment was ABY3-38°C-4 stored at 8°C in regards of probiotics’ viability and sensory characteristics of Doogh. Thus, controlling the temperature of refrigerated storage is the most importance factor during storage and distribution.

Isolation and characterization of exopolysaccharide-producing strains of Lactobacillus bulgaricus from curd.

Curd is the most widespread traditional fermented milk product used by a large population and is a good source of vitamin B, protein, and calcium. In this study, the isolation of exopolysaccharide (EPS)‐producing strains of Lactobacillus delbrueckii subsp. bulgaricus from curd samples was carried out. Identification of EPS‐producing strains was done by Gram staining, catalase activity, sugar fermentation test, API 50 CHL, and PCR analysis. These EPS‐producing strains were subjected for the estimation of technological properties such as titratable acidity, curdling time, acidification rate, and texture. The strains best in their technological properties were selected for the production of yogurt in combination with EPS‐ or non‐EPS‐producing strains of Streptococcus thermophilus. The EPS concentration range was from 41 to 268 mg/L in the yogurt. The highest value of EPS concentration was detected in S. thermophilus and non‐EPS‐producing Lb. bulgaricus after 14 days of storage.

Probiotic Candidates Yeast Isolated from Dangke - Indonesian Traditional Fermented Buffalo Milk

The aim of the study was to isolate and identify the yeast isolated from Dangke and its potential as probiotics. The purified isolates obtained were identified based on observations of macroscopic characteristics of colonies and microscopic cells. The ability as a probiotic yeast is obtained by testing the resistance towards acid conditions, bile salt resistance test and aggregation ability test against pathogenic bacteria using Salmonella sp. The yeast isolates were identified using the RapID Yeast Plus System. The isolation result was obtained D.10.3.d isolate that identified as Candida guilliermondii which showed probiotic characteristic. The yeast colony is round, cream‑colored, smooth surfaces, low convex elevations and entire edges, capable of growing on mediums with the pH of 4, containing 1 % and 5 % of bile salts and having the ability to aggregate Salmonella sp. at 15, 60, and 180 minutes.

Microbiota composition of dadih - a traditional fermented buffalo milk of West Sumatra.

Dadih is an Indonesian traditional spontaneously fermented buffalo milk, produced in West‐Sumatra, which is nutritious and has health benefits. The mechanism of action behind the health benefits is largely unknown, but several probiotic strains have been isolated from dadih, which may contribute to its health properties. To identify the composition of its microbiota, two artisanal dadih samples (n = 8) were collected from four producers. The raw buffalo milk used for fermentation was either pasteurized (n = 4) or not (n = 4), and back‐slopping was used as a starter‐culture (n = 5) or not (n = 3). DNA was extracted from each sample in duplicate and the microbiota composition was determined by 16S‐rRNA‐gene amplicon‐sequencing of the V3–V4 region. PCoA analysis showed clear separation of the samples by producer, but no separation due to pasteurization or use of back‐slopping. Lactococcus (52–83%) predominated in all samples, followed by Klebsiella (5–26%), and Lactobacillaceae, Bifidobacterium (particularly high (c. 18%) in the non‐pasteurized, back‐slopped product from Palupuh), Streptococcus and Leuconostoc. Back‐slopping practice correlated significantly with higher abundance of Lactobacillaceae, Pediococcus, species of the order Burkholderiales, and Serratia, but with lower abundance of several other Enterobacteriaceae (including Klebsiella), Streptococcaceae, Staphylococcus and Brachybacterium. Pasteurization was not significantly correlated with the presence of certain members of the final microbiota. Taken together, fermentation results differ significantly from producer to producer and back‐slopping practice would be advisable.Significance and Impact of the StudyUsing state‐of‐the‐art methods we determined the microbiota composition of dadih, an artisanal, traditional fermented buffalo milk of West Sumatra with health benefits. We show that the artisanal practice leaves room for standardization and optimization with respect to the presence of potential pathogenic species in the final product. The Dadih Initiative in Indonesia aims to expand production of this health promoting product, and the findings help to determine important steps for potential food safety issues and good‐manufacturing‐practices to obtain a safe, nutritious and healthy traditional yoghurt‐like functional food.