Fermented Skim Milk Research Articles

Açai pulp addition improves fatty acid profile and probiotic viability in yoghurt

The effects of açai pulp addition and different probiotic bacteria on the fatty acid profile of stirred yoghurt were examined. Skim milk was divided into two groups: one containing açai pulp and another without the fruit. Batches were inoculated with yoghurt starter culture and divided into five groups according to probiotic addition. Counts of viable microorganisms were measured at days 1, 14 and 28 of cold storage. Fatty acid profile was determined by gas chromatography at day 1. Açai pulp favoured an increase in Lactobacillus acidophilus L10, Bifidobacterium animalis ssp. lactis Bl04 and Bifidobacterium longum Bl05 counts at the end of 4 weeks of cold storage. This study demonstrated that açai pulp addition increased monounsaturated and polyunsaturated fatty acid contents in probiotic yoghurt and enhanced the production of α-linolenic and conjugated linoleic acids during fermentation of skim milk prepared with B. animalis ssp. lactis Bl04 and B94 strains.

Survival of Bifidobacterium pseudocatenulatum G4 during the storage of fermented peanut milk (PM) and skim milk (SM) products.

Survivability of Bifidobacterium pseudocatenulatum G4 in fermented peanut milk (PM) and skim milk (SM) directly or supplemented with fructooligosacharide (FOS) and human grade yeast extract was evaluated under refrigeration and 25°C for a period of 2 weeks. During the study period, the development of lactic acid and short chain fatty acids (acetic, propionic and butyric) were also examined. The fermented products were prepared utilizing inoculum of 0.67% and anaerobic incubation under control conditions using 1 l volume bioreactor to final pH less than 5. Initial mean viable number of strain G4 ranged between 7.12 - 8.35 cfu/ml fermented PM and 7.28 - 8.39 cfu/ml fermented SM based products. The viable strain G4 in fermented samples held at 25°C for 2 weeks decreased to a level of < 7 log cfu/ml due to the pH reductions, which were explained by increases in lactic, acetic, propionic and butyric acids. This final viability of the fermented products is below the requirement to claim probiotic effects upon their consumptions, while at refrigeration (4°C) storage, the viability maintained in fermented products was higher exceeding the mean recommended level of 7 log cfu viable probiotic per ml product generally. Therefore, fermented PM products especially supplemented with FOS containing strain G4 could maintain probiotics effects under refrigeration for a period of 2 weeks.

ACE-inhibitory activity and gamma-aminobutyric acid content of fermented skim milk by Lactobacillus helveticus isolated from Xinjiang koumiss in China

Eighty-one strains of Lactobacillus were isolated from the koumiss collected in Xinjiang, China. The strains were cultivated in skim milk medium, ACE inhibitory activity and GABA concentrations in the culture supernatants were measured. Screening results revealed that ACE inhibitory activity of 16 strains was higher than 50% and two strains produced GABA. The Lactobacillus—ND01 strain produces both the high ACE inhibitory activity and GABA. The sequence of 16S rDNA of the Lactobacillus—ND01 showed 99% homology to L. helveticus. The first identification of the newly isolated Lactobacillus—ND01 strain which produces both high ACE inhibitory activity and GABA revealed differences from reported species in our study. The L. helveticus ND01 was resistant to acidic condition. The results suggest that L. helveticus ND01 showed good potential for application in the management of hypertension.

Acid adaptation affects the viability of Salmonella typhimurium during the lactic fermentation of skim milk and product storage

In this study, Salmonella typhimurium was acid adapted at pH 5.5 for 4 h. The viability of the acid-adapted and non-adapted cells of S. typhimurium was investigated both during the lactic fermentation of skim milk with Streptococcus thermophilus or Lactobacillus bulgaricus, and during the storage of lactic fermented milk products at 5 °C. It was found that the viable population of S. typhimurium, regardless of acid adaptation, increased in skim milk during the initial 24 h of lactic fermentation and then declined. However, the viable population of acid-adapted S. typhimurium was significantly higher ( P < .05) than that of non-adapted cell at the end of 48 h of fermentation. Acid-adapted cells of S. typhimurium were also found to have survived better than non-adapted cells in the S. thermophilus-prepared fermented milk and two commercial lactic fermented milk products. The viability of the acid-adapted and non-adapted S. typhimurium at 5 and 37 °C in cell-free fermented milks that had their pHs adjusted to 6.4 and skim milk (pH 6.4) was further investigated. Results revealed that acid adaptation, in addition to enhancing acid tolerance, reduced the susceptibility of S. typhimurium to refrigerated temperature and other detrimental factors which might be present in lactic fermented milk products. These responses all contribute to the enhanced survival of acid-adapted S. typhimurium in the lactic fermented milk products observed in the present study.

Effect of thermophilic lactic acid bacteria on the viability of Salmonella serovar Typhimurium PT8 during milk fermentation and preparation of buffalo's yogurt

Viability of dairy‐borne Salmonella enterica ssp. enterica serovar Typhimurium PT8 was studied during the fermentation of skim milk by thermophilic lactic acid bacteria (LAB). Longer generation times of Salmonella were found in mixed cultures of skim milk containing Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus or a mixture of them (1:1), as compared with single cultures of the pathogen. Salmonella was less able to survive in mixed cultures with these LAB during prolonged incubation at 41°C and also during cold storage of the fermented milk. Lactobacillus ssp. bulgaricus and its mixture with S. thermophilus were more inhibitory to the growth and survival of Salmonella than was S. thermophilus. This was associated with higher ability of L. ssp. bulgaricus and the mixture to develop acidity in milk than S. thermophilus. Examining the antibacterial activity of these LAB towards Salmonella showed that other factors including heat‐resistant and heat‐labile compounds were involved in inhibiting the pathogen by these cultures. The viability of the same Salmonella strain during the preparation and cold storage of buffalo's yogurt was also examined. Salmonella was found to survive longer in yogurt made with starter containing probiotic bacteria than in that prepared with the traditional starter. This was ascribed to the development of lower pH by the traditional starter.

Longitudinal DXA measurements demonstrate lifetime differences in lean and fat tissue deposition between boars and barrows under individual and group-penned systems

Thirty-two Large White × Landrace male pigs were used to determine the relationships between the rates of tissue deposition and age, in boars and barrows under 2 housing systems. A 2 × 2 factorial design was used, with the respective treatments being sex (boar or barrow) and housing condition (individually penned system or group-penned system). Surgical castration was performed at 7 days of age. Individually housed pigs were used to provide an estimate of potential growth and were weaned at 10 days into individual cages and provided with supplemental fermented skim milk for 2 weeks. Group-housed pigs were weaned at 24 days of age and reared in group pens of boars and castrates typical for commercial production. Conventional weaner, grower, and finisher diets were provided ad libitum to all pigs from weaning onwards. A Hologic QDR4500A dual-energy X-ray absorptiometer (DXA) was used to determine lean, fat, and bone composition at 4-weekly intervals from 10 until 150 days of age. Over the 20 weeks of the study, boars deposited less fat than barrows (136 v. 179 g/day, s.e.d. = 6.49, P &lt; 0.001). Over the same time frame, boars deposited more lean tissue than barrows when individually penned (490 v. 444 g/day, s.e.d. = 14.4, P &lt; 0.05) but there was no difference in group-penned pigs (464 v. 443 g/day, s.e.d. = 14.4, P &gt; 0.1). This was more pronounced in the final 4 weeks of growth when individually penned boars deposited 200 g/day more lean than barrows (P &lt; 0.001), with no increase in group-penned animals. However, during this growth phase, group penning further increased the fat deposition margin between boars and barrows where boars deposited 90 g/day less fat when individually penned (P &lt; 0.001), but 140 g/day less fat (P &lt; 0.001) when group penned. The results show that the advantages of boars in terms of growth and lean tissue composition are substantially reduced in group-penned situations. However, because of fat deposition, boars retain some advantage over barrows in group-penned systems at liveweights over about 50 kg. These data may aid in the accurate prediction of the nutrient requirements and optimum slaughter weight for barrows.

Synthesis and utilisation of folate by yoghurt starter cultures and probiotic bacteria

Thirty-two bacterial isolates from species commonly used in yoghurts and fermented milks were examined for their ability to synthesise or utilise folate during fermentation of skim milk. The organisms examined included the traditional yoghurt starter cultures, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus, and probiotic lactobacilli, bifidobacteria, and Enterococcus faecium. Folate was synthesised by S. thermophilus, bifidobacteria, and E. faecium. S. thermophilus was the dominant producer, elevating folate levels in skim milk from 11.5 ng g −1 to between 40 and 50 ng g −1. Generally, lactobacilli depleted the available folate in the skim milk. Fermentations with mixed cultures showed that folate production and utilisation by the cultures was additive. Fermentations using a combination of Bifidobacterium animalis and S. thermophilus resulted in a six-fold increase in folate concentration. Although increased folate levels in yoghurts and fermented milks are possible through judicious selection of inoculum species, the folate levels remain relatively low in terms of recommended daily allowance.

Removal of skim milk lactose by fermentation using free and immobilized Kluyveromyces marxianus cells

Kluyveromyces marxianus CBS 6164 cells, free or immobilized in Ca-alginate (2%) beads, are able to consume more than 99% of the skim milk lactose in anaerobic conditions. In batches at 30 °C, the lactose consumption after 3.5 h of skim milk fermentation by 30 and 50 g free K. marxianus cells per liter was around 99 and 99.6% respectively, with an approximate conversion of lactose to ethanol and CO2 of 80%. The immobilized cells, easy to handle and showing a faster and easier separation from the fermented medium compared to the free ones, were used in more than 23 batches (cycles of re-use) without losing their activity.

Formula Makanan Glikemik Tinggi Untuk Anak Gizi Kurang

High Glycaemic Food Formula For Under Nourished Children. Background: The reported prevalence of undernounshed children is highly increase since economic crisis. Six months food intervention based on skim milk only improved 65% of the undernourished children. Since gastrointestinal tract of such childrents incapable of digesting high molecular weight of carbohydrate and protein, there is a need to develop an easily digested food formula which has high glycaemic index. Objective: to produce high glycaemic index formula using dextrinized carbohydrate and fermented skim milk that is easily digested for undernourished children. Method: Two groups of subjects, each consists of 34 and 33 undernourished children were given either high glycaemic index formula (test group) or skim milk formula (control group) for 4 months. The food formula compliance, anthropometric measurement, blood and fecal component were analyzed. Results: There were increase in body weight of test group even though not changing their nutritional status based on Z-score. The blood and fecal component data indicated that the high glycaemic formula can be digested well by the undernourished children. Keywords: high glycaemic formula, undernourished

Lower plasma triglyceride level in Syrian hamsters fed on skim milk fermented with Lactobacillus casei strain Shirota.

The effect of fermented skim milk (FSM) by Lactobacillus casei strain Shirota on plasma lipids in hamsters was examined. Hamsters fed on cholesterol-free and -enriched diets containing 30% FSM had lower levels of plasma triglyceride than those fed on the control diet. In the experiment with the cholesterol-enriched diet-fed hamsters, the plasma triglyceride level was suppressed by FSM at concentrations of 10% to 30%. Unfermented milk tended to lower the level of triglyceride, but not significantly. The plasma cholesterol concentration was not affected by an FSM and unfermented skim milk supplement to the diet. L. casei strain Shirota grew well in the presence of mixed lipid micelles containing bile acid, but did not have the ability to remove cholesterol from the culture broth. These results indicate that FSM lowered the plasma triglyceride level in hamsters.

The antimutagenic properties of a polysaccharide produced by Bifidobacterium longum and its cultured milk against some heterocyclic amines

The antimutagenicity and fermentation pattern of three Bifidobacterium longum strains (B. longum, B. longum PS+, and B. longum PS-) in skim milk were studied. The increase in fermentation time significantly increased antimutagenicity with all strains tested against the mutagenicity of both 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) in an Ames-like test using streptomycin-dependent strain SD510 of Salmonella typhimurium TA98. Bifidobacterium longum PS+, a polysaccharide-producing strain, had a longer lag phase but showed the highest inhibition percentage against both mutagens tested. The viability of B. longum PS+ cells was not affected by the low pH of 4.1, probably owing to the protection offered by the polysaccharide produced. The antimutagenicity of the fermented milk against Trp-P-1 was dose dependent. The strains were also able to bind with different amino acid pyrolysates, and B. longum showed the highest binding. Acetone extracts of fermented skim milk dissolved in water showed less antimutagenicity than extracts dissolved in dimethylsulfoxide. The isolated crude polysaccharide from B. longum PS+ showed a dose-dependent inhibition of the mutagenicity of Trp-P-1. Thus, we conclude that the polysaccharide of B. longum PS+ can be used as an antimutagen.Key words: Bifidobacterium longum, polysaccharides, fermented milk, heterocyclic amines.

Survivability and β‐galactosidase activity of bifidobacteria stored at low temperatures

This work evaluated the ability of strains representing six species of Bifidobacterium with probiotic potential to survive and maintain β‐galactosidase activity through a two‐step, low‐temperature storage period. Cultures were also evaluated for their ability to ferment skim milk and retain viability during storage at 4°C. Bifidobacterium longum ATCC 15707, B. breve 15700, and B. bifidum 29521 maintained the greatest viabilities at > 1 x 107 CFU/mL, and B. infantis 15702 maintained the highest β‐galactosidase activity at > 1 U/ml (with < 1 × 105 CFU/mL) after ‐60 to 4°C storage. In fermented skim milk, B. breve 15700, B. bifidum 29521, and B. animalis 25527 tolerated a final product pH of 4.75 with > 1 × 108 CFU/mL remaining after 14 days of storage at 4°C. Overall, it was found that highest levels of β‐galactosidase activities did not necessarily correlate to the highest plate‐count populations.

The antimutagenic properties of a polysaccharide produced by &lt;i&gt;Bifidobacterium longum&lt;/i&gt; and its cultured milk against some heterocyclic amines

The antimutagenicity and fermentation pattern of three Bifidobacterium longum strains (B. longum, B. longum PS+, and B. longum PS-) in skim milk were studied. The increase in fermentation time significantly increased antimutagenicity with all strains tested against the mutagenicity of both 3-amino-1,4-dimethyl-5H-pyrido-[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) in an Ames-like test using streptomycin-dependent strain SD510 of Salmonella typhimurium TA98. Bifidobacterium longum PS+, a polysaccharide-producing strain, had a longer lag phase but showed the highest inhibition percentage against both mutagens tested. The viability of B. longum PS+ cells was not affected by the low pH of 4.1, probably owing to the protection offered by the polysaccharide produced. The antimutagenicity of the fermented milk against Trp-P-1 was dose dependent. The strains were also able to bind with different amino acid pyrolysates, and B. longum showed the highest binding. Acetone extracts of fermented skim milk dissolved in water showed less antimutagenicity than extracts dissolved in dimethylsulfoxide. The isolated crude polysaccharide from B. longum PS+ showed a dose-dependent inhibition of the mutagenicity of Trp-P-1. Thus, we conclude that the polysaccharide of B. longum PS+ can be used as an antimutagen.

Antimutagenicity of components of dairy products

This paper reports the potential antimutagenicity of some components of dairy products. For both milk and fermented milk, Bifidobacterium sp. Bio (strain Danone 173010), casein and calcium showed a dose-dependent antimutagenic activity against benzo[ a]pyrene mutagenicity in the Ames test using Salmonella typhimurium TA98. Fatty compounds present in milk had no antimutagenic effect. At the level occurring in cultured or uninoculated milks, and even more, the bifidobacteria, casein and calcium showed less antimutagenic activity than fermented and uninoculated milks. So, the mix of all these components must contribute to the total protective effect of dairy products against induced mutagenicity, and this does not rule out the possiblity of contribution of other unknown substances. The total antimutagenicity of uninoculated skim milk corresponds to the additional activity of casein and calcium. The observed antimutagenic activity of fermented skim milk remains lower than expected.

Effect of dairy products on initiation of precursor lesions of colon cancer in rats

This study reports the modulating effect of some dairy products on initiation of putative preneoplasic lesions in rat colon (aberrant crypts) by 1,2-dimethylhydrazine dihydrochloride. Uninoculated skim milk, skim milk fermented with Bifidobacterium sp Bio (Danone strain 173010), and a suspension of the same lactic acid bacteria were incorporated in the animals' diet. The tested diets significantly reduced the incidence of aberrant crypts compared with the control diet by 51%, 49%, and 61%, respectively. The effects of the diets on cecal pH, hepatic UDP-glucuronyltransferase activity, and cecal microflora enzyme beta-glucuronidase were also studied. There was no significant difference in cecal pH between rats fed experimental diets and control rat. The diet supplemented with the Bifidobacterium strain suspension significantly decreased only the cecal beta-glucuronidase activity. Both enzyme activities were reduced in rats fed fermented skim milk- or uninoculated skim milk-supplemented diets compared with control animals.

Rapid isolation and estimation of polysaccharide from fermented skim milk with Streptococcus salivarius subsp. thermophilus by coupled anion exchange and gel-permeation high-performance liquid chromatography

Rapid isolation and estimation of polysaccharide from fermented skim milk with <i>Streptococcus salivarius</i> subsp. <i>thermophilus</i> by coupled anion exchange and gel-permeation high-performance liquid chromatography

EFFECT OF PAPAYA PULP ADDITION ON THE GROWTH OF LACTOBACILLUS ACIDOPHILUS

ABSTRACTEffect of papaya pulp addition to skim milk on the growth characteristics of five strains of Lactobacillus acidophilus was investigated. All the strains tested exhibited higher viable counts, shorter generation time, increased acid production, greater sugar utilization and fall in pH upon addition of papaya pulp. The generation time, acid production, sugar utilization and pH values at the end of 18 h fermentation of skim milk by different strains were 150–200 min, 0.29–1.73%, 0.39–2.22 g/100 mL and 3.85–6.10, respectively. The corresponding values for 10% papaya pulp added skim milk blend were 120–143 min, 0.51–1.84%, 0.70–2.79 g/100 mL and 3.70–5.10, respectively. Organoleptic evaluation revealed that papaya pulp addition imparted firmness to the coagulum and thus enhanced the acceptability of the product by eliminating the problem of wheying‐off and improved flavor.

Fermentation of Ultrafiltered Skim Milk Retentates with Mesophilic Lactic Cheese Starters

Acid production and its relation to pH changes by commercial, direct-set frozen concentrated lactic starters in skim milk and 2:1 skim milk retentates were studied. Retentates resisted pH change below pH 5.2 despite the production of large amounts of lactic acid by starter bacteria. Control skim milk required 6h at 32°C to attain pH 4.6, but skim milk retentates incubated similarly could not be fermented to this pH even after 8.5h. Doubling the starter inoculum in the retentate led to pH 4.6 in 7.5h. Direct-set starter DS1, with more bacteria numbers than direct-set starter DS2, fermented skim milk and 2:1 skim milk retentate more rapidly.

Biosynthesis and Utilization of Folic Acid and Vitamin B12 by Lactic Cultures in Skim Milk

Fermentation of skim milk by Streptococcus thermophilus and Lactobacillus acidophilus increased the folate concentration by more than 200%. The increase was dependent on time of incubation with the maximums between 8 to 24h. However, L. bulgaricus reduced folic acid to negligible within a few hours. Vitamin B12 content did not increase, regardless of culture. Our results and those of others suggest that contradictions of biosynthesis of folic acid and B12 by lactic cultures may have been from several factors, such as species and strain of culture and incubation time. Precursors of folate–para-aminobenzoic acid and guanosine triphosphate – did not increase folate when added to the skim milk prior to fermentation by the lactic cultures.

Inhibition of Enteropathogenic Escherichia coli by Homofermentative Lactic Acid Bacteria in Skimmilk

Behavior of enteropathogenic and nonpathogenic strains of Escherichia coli was determined when they were grown in skimmilk with and without 0.25 or 2.0% added lactic starter and incubated at 21 or 32 C for 15 h, and then after refrigeration at 7 C. With no lactics present, generation times for E. coli ranged from 28 to 35 min at 32 C and from 66 to 109 min at 21 C. At 32 C, after an initial 1- to 3-log increase in numbers and 6 to 9 h of incubation, E. coli was completely inhibited by both concentrations of starter culture. Complete inhibition of growth by E. coli occurred earlier at 32 than at 21 C, but smaller numbers of E. coli were obtained at 21 C; some strains virtually did not grow. The final pH of fermented milks ranged from 4.4 to 4.6. The longest survival time for E. coli in refrigerated fermented milk was about 17 days when milk was fermented at 32 C with 0.25% starter. A combination of lower incubation temperature (21 C) and higher starter concentration (2.0%) was most effective in controlling growth of E. coli in fermented skimmilk.