Fermented Skim Milk Research Articles

The Effect of Probiotic Yogurt and Fermented Skim Milk Beverages on The Reduction of Streptococcus Mutans In Children's Dental Caries

The Effect of Probiotic Yogurt and Fermented Skim Milk Beverages on The Reduction of Streptococcus Mutans In Children's Dental Caries

Effects and improvement mechanisms of ultrasonic pretreatment on the quality of fermented skim milk

Fermented skim milk is an ideal food for consumers such as diabetic and obese patients, but its low-fat content affects its texture and viscosity. In this study, we developed an effective pretreatment method for fermented skim milk using low-frequency ultrasound (US), and investigated the molecular mechanism of the corresponding quality improvement. The skim milk samples were treated by optimal ultrasonication conditions (336 W power for 7 min at 3 °C), which improved the viscosity, water-holding capacity, sensory attributes, texture, and microstructure of fermented skim milk (P < 0.05). Further mechanistic analyses revealed that the US treatment enhanced the exposure of fluorescent amino acids within proteins, facilitating the cross-linking between casein and whey. The increased surface hydrophobicity of fermented milk indicates that the US treatment led to the exposure of hydrophobic amino acid residues inside proteins, contributing to the formation of a denser gel network; the average particle size of milk protein was reduced from 24.85 to 18.06 µm, which also contributed to the development of a softer curd texture. This work is the first attempt to explain the effect of a low-frequency ultrasound treatment on the quality of fermented skim milk and discuss the molecular mechanism of its improvement.

Combination of bifidobacteria and arabinogalactan when fermenting skim milk

The work investigated the fermentation of skim milk with a concentrate of bifidobacteria (Bifidobacterium bifidum, Bifidobacterium longum, Bifidobacterium adolescentis, Bifidobacterium breve and Bifidobacterium infantis) in the presence of arabinogalactan in amounts of 3, 5, 7 and 10%. It was found that after fermentation at a temperature of 37 °C for 12 hours, the characteristic sour-milk taste and curd were not observed in any of the samples, regardless of the presence of arabinogalactan. It was revealed that after storage at a temperature of (4±2) °C for 10 days, the consistency of the control and test samples remained homogeneous, without separation and visible syneresis. The increase in titratable acidity at the post-oxidation stage for 10 days was no more than 1-2 °T. It was shown that, under experimental conditions, the number of viable bifidobacteria cells was greater in test samples containing from 5 to 10% arabinogalactan than in control variants and in samples with a mass fraction of arabinogalactan of 3%. Based on the totality of the observed results, it can be assumed that the prebiotic was used by microorganisms as a source of nutrition.

Effect of different proteases on the performance of Lactiplantibacillus plantarum LIP-1 microcapsules prepared by hydrolysing milk proteins

Considering the wide application of probiotics in dairy products, how to use milk proteins as a wall material to embed probiotics is an area of interest. To study the method of embedding microcapsules of milk proteins and improve the survival rate of probiotics during processing, storage and consumption, the ability of different proteases to hydrolyse milk proteins for the preparation of Lactiplantibacillus plantarum LIP-1 microcapsules was evaluated. Microcapsules prepared with chymosin, papain or bromelain significantly improved the survival rate of L. plantarum LIP-1 in an adverse environment (p < 0.05). Further analysis revealed that the hydrolysis of casein was enhanced by chymosin in fermented skim milk, and more protein fragments suitable for microencapsulation were produced. Chymosin microcapsules had a regular spherical shape, dense surface pores, and high microencapsulation efficiency. The survival rate of L. plantarum LIP-1 in simulated gastric fluid, and the storage period, were significantly longer (p < 0.05).

Identification of new reference genes for colony counting by reverse-transcription quantitative PCR in Bifidobacterium animalis

Bifidobacterium animalis, one of the predominant bacteria in the intestines of humans and other mammals, is widely added to dairy products. We employed RNA sequencing to analyze gene expression variance on a genome-wide scale and found stable reference genes (RG) in B. animalis. A total of 1,665 genes were identified by analyzing the data from the transcriptome under 4 different conditions, and 13 probable candidate RG with variation coefficient values <0.1 were validated using reverse-transcription quantitative PCR (RT-qPCR). The amplification efficiency of candidate RG were ranging from 94.16% to 126.25%. We integrated the analysis results of BestKeeper, geNorm, NormFinder, and RefFinder algorithms and revealed that rplD and atpA comprehensive ranked 1.68 and 2.82, respectively, which were more stable than traditional RG. Compared with plate count (1.58 × 106 cfu/mL), the concentrations of B. animalis AR668 by RT-qPCR using rplD, atpA, and 16S rRNA as RG were 2.27 × 106, 2.24 × 106, and 6.66 × 106 cfu/mL, respectively, after 10 h of fermentation in fermented skim milk. It suggested that rplD and atpA as RG can be accurate for colony counting of B. animalis. Our study provides the foundation for more accurate analysis of colony counting by RT-qPCR of B. animalis in dairy foods.

Effect of adding dried jambolan pulp (Syzygium cumini) to potentially symbiotic fermented milk

The aim of this research was to determine the technological viability of adding dried jambolan pulp to potentially symbiotic fermented milk. Jambolan pulp samples were obtained from fruit from the city of Bambuí, MG, and four fermented milk formulations were obtained with different proportions of dried jambolan pulp (0, 1, 2 and 3%). Physicochemical and microbiological analyses were carried out in a 4x4 factorial scheme at different evaluation times (0, 10, 20 and 30 days). The results of the physicochemical analyses carried out on the dried pulp showed that this ingredient has moderate antiox/idant activity (41.88% according to the DPPH method) and is rich in phenolic compounds (235 mg GAE 100 g-1). The fermented milk’s antioxidant activity and phenolic content became higher as the proportion of jambolan pulp increased. The acidity, protein and lipid values were within the standards established by the Regulation of Identity and Quality for fermented skim milk. The treatments’ lactic acid bacteria count showed values greater than 6,00 log CFU g-1 and presented the minimum count required to be classified as potentially probiotic fermented milk. The combination of Lactobacillus casei and jambolan pulp resulted in a potentially functional product with feasible industrial application.

Utilization of banana puree fermented by Lactobacillus acidophilus LA5 and Bifidobacterium lactis BB12 for the manufacture of synbiotic ice cream

In this study, manufacturing synbiotic ice cream is containing fermented banana puree by Lactobacillus acidophilus LA5 and Bifidobacterium (Bif) lactis BB12 and probiotic ice cream containing fermented skim milk by the same bacteria under the same conditions. The Viability of probiotic starters, pH and sensorial properties were tested during the storage period, in addition to the overrun. Synbiotic ice cream showed high bacterial count for both species of probiotics, especially Ice.4 treatment (ice cream containing 10% fermented banana puree with same couple strains) which was 7.54 and 7.59 logarithmic (log) colony- forming unit (CFU)/ gram (g) for Lactobacillus (Lb). Acidophilus LA5 and Bif. lactis BB12, respectively, pH registered 5.7, sensorial attributes recorded 84% and overrun reached 78% compared to others trials that inoculated with 5% of the same puree or ice cream with fermented skim milk with (5,10) % or control treatment (without starters).

Milk fermented by combined starter cultures comprising three Lactobacillus strains exerts an alleviating effect on loperamide-induced constipation in BALB/c mice.

Fermented dairy food, such as yogurt, exhibits some beneficial effects on consumers, including alleviating constipation. In this study, Lactobacillus delbrueckii subsp. bulgaricus DPUL-36, Lactobacillus paracasei DPUL-40 and Lactobacillus paracasei DPUL-44 were used as combined starter cultures at a bacterial cell ratio of 1 : 1 : 1 for reconstituted skim milk fermentation. The milk fermented with the combined starter culture showed good sensory properties. During the storage period, the yogurt showed high lactic acid bacteria vitality and quality stability. Constipated BALB/c mice induced by loperamide (Lop) were orally administered with the combined starter culture fermented milk for 14 days. The results clearly showed that oral administration of the fermented milk relieved Lop-induced constipation in the mice, as evidenced by the significantly increased fecal water content, reduced first black stool time, improved gastrointestinal transmission rate, recovered colon tissue damage, increased level of excitatory neurotransmitters (motilin, gastrin, and substance P) and reduced level of inhibitory neurotransmitters (vasoactive intestinal peptide, somatostatin and endothelin-1) of the mice. Compared with the mice in the Lop group, oral administration of the fermented milk significantly increased the concentrations of acetic acid, propionic acid, butyric acid, isovaleric acid and valeric acid in the feces of the mice, and furthermore, exerted a regulatory effect on the gut microbiota of the mice by up-regulating the abundance of Lactobacillus and Bacteroides, and decreasing the abundance of Helicobacter, Pseudomonas and Porphyromonas. Our results indicated that the combined starter culture fermented milk can effectively alleviate Lop-induced-constipation in BALB/c mice. The relationship between the nutrient profiles and the health promoting function of the yogurt should be further illustrated.

Development of Functional Synbiotic Flavored Fermented Skim Milk Drinks Supplemented with Doum (&amp;lt;i&amp;gt;Hyphaene thebaica&amp;lt;/i&amp;gt; L.) and Carob (&amp;lt;i&amp;gt;Ceratonia siliqua&amp;lt;/i&amp;gt;) Fruits Powder for Nutritional, Antimicrobial and High Antioxidant Activities

The present study was carried out to make new healthy synbiotic flavored fermented skim milk drinks (SFFSD) supplemented with either Doum (Hyphaene thebaica L.) or Carob (Ceratonia siliqua) fruits powder for nutritional, antioxidant and antimicrobial activities. The HPLC analysis showed higher phenolic and flavonoid content in Doum extract than that of Carob. The antimicrobial activity of the methanolic extracts of both Doum and Carob against foodborne pathogens showed that the most sensitive indicators were Bacillus cereus, C. albicans and S. aureus, followed by T. mentagrophyte and E. coli wherein, the diameter of clear zones was, 29, 27, 24, 23 and 13 mm, respectively. While no effect was noticed against Aspergillus flavus. On the other hand, the methanolic extract of Carob fruit exhibited only a weak antibacterial effect against B. cereus (20 mm). Six treatments of SFFSD were made using both Doum or Carob fruit powder as prebiotic and Lactobacillus paracasei as probiotic bacteria. The added levels from Doum were 2%, 4% and 6%, while that added from Carob were 5%, 10% and 15%. Adding Doum and Carob powder increased the containing of minerals; Ca, K, Mg and iron compared with control. Both viscosity and viability of L. paracasei for the SFFSD were increased with increasing the added levels from either Doum or Carob, compared with the control. Samples of SFFSD containing Carob powder, show superior sensory for all parameters and total score points during storage period, especially at a level of 10%. It seems evident that samples supplemented with Doum powder were also acceptable.

Identification and Effects of Skim Milk-Derived Bioactive Antihypertensive Peptides

Bioactive peptides are generated during milk fermentation or enzymatic hydrolysis. Lactobacillus (L) helveticus is commonly used to produce some types of fermented milk products. Fermented milk derived bioactive peptides are known to be beneficial in human health. Anti-hypertensive peptides play a dual role in the regulation of hypertension through the production of the vasoconstrictor angiotensin II and its inactivation of the vasodilator bradykinin. MALDI MS/MS, nano-LC/MS/MS and RP-HPLC were used to isolate peptides showing angiotensin converting enzyme inhibition (ACE-I) from 12% fermented skim milk using a combination of L. helveticus and Flavourzyme®. The fermentation procedure facilitated the identification of 133 anti-hypertensive peptides and 75% short chain amino acids, and the three with the highest ACE-I activity reduced blood pressure in a rat model of hypertension. The freeze- dried extract was supplemented in rodent chow. In this study 14-week-old male spontaneously hypertensive rats were fed for 10 weeks with the identified peptides added to chow and compared to controls supplemented with skim milk powder. Blood pressure (BP) decreased significantly (p &lt; 0.05) from 6 to 10 weeks of FS groups (120/65 mmHg) compared with the NFS control groups, where the BP increased significantly (220/150 mmHg) (p &lt; 0.05). The F6 fraction provided bioactive peptides with stronger antihypertensive properties than other fractions. Skim milk fermented by L. helveticus and Flavourzyme® generates several bioactive peptides which have a blood pressure lowering effect in hypertensive disease.

Proteolytic activities of combined fermentation with Lactobacillus helveticus KLDS 1.8701 and Lactobacillus plantarum KLDS 1.0386 reduce antigenic response to cow milk proteins

Cow milk protein is one of the leading food allergens. This study aimed to develop an effective method for reducing milk sensitization by evaluating antigenicity of fermented skim milk protein using Lactobacillus helveticus KLDS 1.8701, Lactobacillus plantarum KLDS 1.0386, and a combination of both strains. The proteolytic systems of strains in terms of genotype and phenotype are characterized by complete genome sequence, and evaluation the antigenicity of skim milk proteins was determined by ELISA and liquid chromatography with tandem mass spectrometry. Our results showed that the genomes encoded a variety of peptidase genes. For fermented skim milk, the degree of hydrolysis of the combined strains was higher than that of individual strain. Electrophoresis showed that the band color density of α-casein (α-CN) by fermentation of the combined strains was reduced when compared with control group. The fermentation process of the combined strains inhibited α-CN, β-lactoglobulin, and α-lactalbumin antigenicity by 69.13, 36.10, and 20.92, respectively. Major allergic epitopes of α-CN and β-lactoglobulin were cleaved by abundant proteases of combined strains. In all, this study showed that the fermentation process involving both L. helveticus and L. plantarum strains could reduce cow milk protein allergenicity through the combination of cell-envelope proteinase and peptidase on α-CN.

Identification and Transferability of Tetracycline Resistance in Streptococcus thermophilus during Milk Fermentation, Storage, and Gastrointestinal Transit

The existence of antibiotic-resistant bacteria in food products, particularly those carrying acquired resistance genes, has increased concerns about the transmission of these genes from beneficial microbes to human pathogens. In this study, we evaluated the antibiotic resistance-susceptibility patterns of 16 antibiotics in eight S. thermophilus strains, whose genome sequence is available, using phenotypic and genomic approaches. The minimal inhibitory concentration values collected revealed intermediate resistance to aminoglycosides, whereas susceptibility was detected for different classes of β-lactams, quinolones, glycopeptide, macrolides, and sulfonamides in all strains. A high tetracycline resistance level has been detected in strain M17PTZA496, whose genome analysis indicated the presence of the tet(S) gene and the multidrug and toxic compound extrusion (MATE) family efflux pump. Moreover, an in-depth genomic analysis revealed genomic islands and an integrative and mobilizable element (IME) in the proximity of the gene tet(S). However, despite the presence of a prophage, genomic islands, and IME, no horizontal gene transfer was detected to Lactobacillus delbrueckii subsp. lactis DSM 20355 and Lactobacillusrhamnosus GG during 24 h of skim milk fermentation, 2 weeks of refrigerated storage, and 4 h of simulated gastrointestinal transit.

Chromatographic Characterization and In Vitro Bioactivity Evaluation of Lactobacillus helveticus Hydrolysates upon Fermentation of Different Substrates

Among various food sources, milk proteins remain the major vector for functional peptides endowed with several biological activities. Particularly, the proteolytic activity of lactic acid bacteria during milk fermentation has been one of the most followed strategies to produce bioactive peptides. In the present study, the exploration of the activity of several starter cultures, at different fermentation times, was firstly investigated by reversed phase-high performance liquid chromatography. Among the tested strains, Lactobacillus helveticus showed a higher proteolytic activity and it was submitted to further investigations by changing the fermentation substrate (skim milk, brain heart infusion, peptone water) as well as the extraction strategy (trichloroacetic acid vs. glass beads). The chromatographic analyses and the in vitro antioxidant and antihypertensive assays highlighted considerable differences for L. helveticus hydrolysates from different substrates, while a negligible impact by the two extraction protocols emerged. Furthermore, nano-high pressure liquid chromatography coupled with a high resolution mass spectrometry analyzer allowed the preliminary discrimination of fractions from fermented skim milk, likely responsible for the found activity. The obtained results suggest the possibility of varying the fermentation parameters in order to maximize the functional effects of the bioactive peptides.

Effect of milk phospholipids on the growth and cryotolerance of lactic acid bacteria cultured and stored in acid whey-based media

Increasing interest in foods beyond their nutritional value has promoted the development of various novel functional foods that could convey multiple health benefits to consumers. The application of lactic acid bacteria (LAB) and milk phospholipids (MPL) in combination has shown some amplifying effects on the health benefits provided by both ingredients. Freezing is commonly used in LAB preservation and storage. However, the freezing/thawing process damages cell membranes and leads to a loss in viability and functionality of LAB. This study aimed to investigate the influence of MPL on growth and cryotolerance of LAB using acid whey-based medium (AWM) supplemented with 0.5% MPL. Fourteen LAB strains were initially screened from 124 LAB using acid whey-based medium (AW). We then evaluated the cell viability and acidification ability, using the plate counting method and skim milk fermentation test, respectively, of the 14 strains cultured in AW and AWM before and after 3 cycles of freezing/thawing. The presence of 0.5% MPL in AWM significantly promoted the growth of LAB. Supplementing the culture and storage medium with 0.5% MPL significantly enhanced the resistance of selected LAB to freeze-thaw cycles in terms of cell viability and acidification ability. These results suggest that supplementing with 0.5% MPL might promote the growth of LAB and enhance the cryotolerance of LAB cultures in fermented dairy products. This finding leads to a better understanding of the synergistic effects contributed by the LAB–MPL combination and promotes the development of new LAB–MPL functional products.

The Prospective Beneficial Effects of Red Laser Exposure on Lactocaseibacillus casei Fermentation of Skim Milk.

Probiotic lactic acid bacteria are crucial producers of fermented dairy products that are popular functional foods in many countries. The health benefits of probiotic bacteria are mainly attributed to their effective bioactive metabolites. The quality of fermented milk is mainly dependent on the bacterial strain used in the fermentation process. In this study, an innovative technique is used in order to enhance the activities of the probiotic bacteria, quality of fermented milk, and consequently the whole fermentation process. Red laser dosages, at the wavelength of 632.7 nm, were applied to the type strain Lacticaseibacillus casei NRRL-B-1922 before the fermentation of skim milk. The results revealed that the scavenging of 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and total antioxidant capacity were significantly increased from 21% in untreated control to 56% after bacterial laser irradiation of 12 J/cm2 dosage for 40 min. The antioxidant activity was found to be increased as the red laser dosage increased in a dose-response relationship. Additionally, the lactose fermentation in skim milk medium of 43.22 mg/mL initial concentration into organic acids was enhanced after L. casei irradiation and recorded 23.15 mg/mL compared to control group 28.35 mg/mL without bacterial pre-treatment. These results are correlated with increase of the β-Galactosidase activity, where the L. casei that has been exposed to 40 min of red laser exhibited the higher activity of a 0.37 unit/mL relative to the control 0.25 unit/mL. The assessment of this fermented milk after L. casei laser exposure for 10, 20, and 40 min indicates multiple biological effects, including assimilation of cholesterol as well as proteolytic and antibacterial activity. Our data on the exposure of L. casei to laser beam suggest promising application of red laser in the fermentation process of skim milk.

Effect of Addition of Jerusalem Artichoke (Helianthus Tuberosus) Tubers Powder, and Inulin on Lactobacillus Reuteri Activity and Recovery After Freezing Injury

This study indicated that the addition of 2% of Jerusalem artichoke (Helianthus tuberosus) tubers powder (JTP) exceeded the activity of Lactobacillus reuteri in comparison with inulin and control treatment. The number of bacteria after the activation period 24 hours/37°C increased in the skim milk added 1, 2 and 5% JTP to 70 × 106, 210 × 108 and 119 × 107 Colony Forming Unit (cfu)/ml respectively. While the number of bacteria in the skim milk supported by addition 1, 2 and 5% Inulin was 56 × 107, 83 × 107 and 74 × 106 cfu/ml. While in the control treatment was 44 × 106 cfu/ml. The results indicated that the addition of 2% of the JTP contributed well to the preservation bacterial viability during period of storage at 4°C/7 days and frozen storage at -18°C/60 days. The number of bacteria in the fermented skim milk was supported by 1, 2 and 5% JTP 90 × 107, 200 × 107, 63 × 107 cfu\\ml respectively after cooling period, while it reached 30× 102,22×102 and 6 × 102 cfu\\ml respectively after freezing period, while the numbers of bacteria in the control treatment were 44 cells/g only. The results indicated that the addition of 2% of the inulin was superior in keeping the numbers of bacteria during the frozen storage period at -18°C/60 days compared to the refrigerated storage at 4°C/30 days, the number of bacteria in the fermented milk and supported by 1, 2 and 5% of the inulin 72×107,83×107 and 63×107 cfu\\ml after the cooling period respectively, while in frozen milk was 36×103, 47×103 and 50 ×103cfu\\ml. The results also indicated the positive role of the addition of 2% JTP in the recovery of injure cells after the end of the frozen storage period -18°C/60 days where the number of cells at activation period following the freezing increased from 44 cells/ml to 71×104cfu\\ml, While the number of the media which supported by inulin was 48×103cfu\\ml and in the was control 57×102c.f.u\\ml.

Viability of acid-adapted and non-adapted Bacillus cereus during the lactic fermentation of skim milk and product storage at 5°C

In this study, Bacillus cereus was subjected to acid adaptation at pH 6.3 for 40 min. It was found that acid-adapted B. cereus exhibited a higher survival percentage than non-adapted cells after exposure to an acidic condition of pH 4.6. The viable population of both acid-adapted and non-adapted B. cereus increased during the first 12-18 hr of lactic fermentation of skim milk by Streptococcus thermophilus or Lactobacillus bulgaricus, and then declined as the fermentation extended. However, the acid-adapted cells exhibited a lower population reduction rate than the non-adapted B. cereus. A higher viable population of acid-adapted B. cereus than the non-adapted cells was also noted in Str. thermophilus-fermented skim milk and the two commercial lactic fermented products kept at 5°C. Additionally, the acid adaptation could reduce the susceptibility of B. cereus to acidity, refrigerated temperature and other detrimental principles present in lactic fermented milk products.

Probiotic Properties of Lactobacillus brevis KU200019 and Synergistic Activity with Fructooligosaccharides in Antagonistic Activity against Foodborne Pathogens.

This study aims to evaluate the probiotic properties of Lactobacillus brevis (L. brevis) KU200019 and the synergistic activity with prebiotics on antimicrobial activity, and the potential application as an adjunct culture in fermented dairy products. The commercial strain, L. brevis ATCC 14869 was used as reference strain. L. brevis KU200019 was showed higher viability in simulated gastric (99.38±0.21%) and bile (115.10±0.13%) conditions compared to reference strain. L. brevis KU200019 exhibited antimicrobial activity against various foodborne pathogens. The supplementation of fructooligosaccharides (FOS) enhanced viability of lactic acid bacteria (>8 Log CFU/mL) and antioxidant activity [2,2-diphenyl-2-picrylhydrazyl radical assay (DPPH) assay, 31.23±1.14%; 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assay, 38.82±1.46%] in fermented skim milk during refrigerated storage. L. brevis KU200019 was distinguished from the reference strain by its higher probiotic potential, antimicrobial activity, and higher antioxidant activity in fermented milk. Therefore, L. brevis KU200019 with FOS was demonstrated promising properties for further application in fermented dairy products with enhanced safety and quality.

The Effect of Probiotic in Milk Fermentation Towards Decreasing Cholesterol Levels: in Vivo Studies

Hypercholesterolemia is a disease that is indicated by the increasing level of cholesterol in the body and also as one of the factors causing cardiovascular disease. An alternative that can be done to prevent hypercholesterolemia is by consuming fermented milk. Skim milk is fermented using probiotic of Lactobacillus acidophillus, Lactobacillus plantarum and Streptococcus thermophilus. The skimmed milk that has been fermented is then tested for total lactic acid bacteria, total acid, pH, and in vivo analysis for antihypercholesterolemia activity using animal model. In this study, the animal models used were male white rats which were grouped into three treatment groups, namely negative control, positive control, and fermented milk group. The result of the study shows that the total lactic acid bacteria, total acid and pH of fermented skim milk were 5.25 x10 9 CFU/ml ; 2.190% and pH 4.06, respectively. From the results, fermented milk with probiotics has the ability to reduce cholesterol levels in the blood of male white rats effectively in vivo.

Safety and Stability of Two Potentially Probiotic Lactobacillus Strains After In Vitro Gastrointestinal Transit

According to FAO and WHO, probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Most probiotic bacteria used today belong to the genera Lactobacillus and Bifidobacterium and are of animal or human origin. The fundamental characteristic routinely evaluated in potential probiotics strains is their limited viability loss during gastrointestinal transit (GIT), but to date, no studies reported whether probiotics, besides viability, still also maintain their beneficial properties intact. To study this aspect, we considered two strains, Lactobacillus rhamnosus DTA 79 and L. paracasei DTA 83, previously characterised for the presence of some probiotic properties, isolated from faeces of 7- to 21-day-old babies. Here, we examined some additional properties, namely antibiotic resistance, resistance to lysozyme, presence of haemolytic activity and inhibition of pathogen biofilm formation. We then tested the effect of in vitro GIT on all these features and our results show evidence that this procedure had in some cases limited and in others no significant effects on them. Additionally, we examined the gastrointestinal resistance of the strains after skim milk fermentation and successive storage of the product for 20 and 40days at refrigeration temperature, to see whether prolonged storage could weaken cell resistance to GIT. Our results demonstrate that a protracted refrigeration period before in vitro GIT did not affect or influenced very weakly this essential probiotic property.