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

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

Survival and activity of 5 probiotic lactobacilli strains in 2 types of flavored fermented milk

The viability of 5 probiotic lactobacilli strains (Lactobacillus acidophilus LA-5, Lactobacillus casei L01, Lactobacillus casei LAFTI L26, Lactobacillus paracasei Lcp37, and Lactobacillus rhamnosus HN001) was assessed in 2 types of probiotic flavored drink based on fermented milk during 21 days of refrigerated storage (5°C). Also, changes in biochemical parameters (pH, titrable acidity, and redox potential) during fermentation as well as the sensory attributes of final product were determined. Among the probiotic strains, L. casei LAFTI L26 exhibited the highest retention of viability during refrigerated storage period, while L. acidophilus LA-5 showed the highest loss of viability during this period. The decline in cell count of probiotic bacteria in strawberry fermented milk was significantly greater compared to peach fermented milk. In an overall approach, peach fermented milk containing L. casei LAFTI L26 was selected as the optimal treatment in this study in both aspects of viability and sensory accpeptibility.     

Optimisation of probiotic yoghurt production enriched with phytosterols

To optimise the formulation of phytosterol‐enriched probiotic yoghurt, the effect of different concentrations of phytosterols, fat and the probiotic inoculation rate on the survival of Lactobacillus acidophilus LA‐5, Bifidobacterium lactis BB‐12 and physicochemical indices over 14 days of storage was explored. Data analysis showed that the phytosterol concentration and fat content were two crucial factors affecting probiotic viability. Addition of phytosterols had no adverse effect on the overall scores for sensory attributes. Regarding maximisation of viability and storage time, the optimum conditions were found to be fat = 8.07% (w/v), phytosterol = 18 g/L, probiotic inoculation rate = 71.42 mg/L and storage time = 12 days.     

Effect of cryoprotectants,prebiotics and microencapsulation on survival of probiotic organisms in yoghurt and freeze-dried yoghurt

The survival of probiotic microorganisms including Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus rhamnosus and Bifidobacterium spp. was evaluated in yoghurt and freeze-dried yoghurt after processing and storage. The effectiveness of microencapsulating probiotic organisms as well as adding cryoprotectants and prebiotics in improving their viability was also investigated. The viability of Bifidobacterium infantis 17930 and L. rhamnosus GG was reduced by 0.07 log, while that of L. casei 1520 and Bifidobacterium longum 1941 was reduced by 0.28 and 0.39 log, respectively. There was a 7% improvement in the viability of L. casei 1520 when cryoprotectant ‘Unipectine™ RS 150’ was added at 2.5% (w/v). The prebiotic ‘Raftilose^®P95’ when added at 1.5% w/v to yoghurt improved the viability of the combined selected probiotic organisms by 1.42 log during four weeks of storage at 4 °C. Microencapsulation with alginate improved viability of combined selected probiotic organisms by 0.31 log in freeze-dried yoghurt stored at 21 °C.     

A new synbiotic dairy food containing lactobionic acid and Lactobacillus casei

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

The biological activity of fermented milk produced by Lactobacillus casei ATCC 393 during cold storage

Lactobacillus casei ATCC 393 is an important probiotic strain widely known in dairy technology. However, its capability to produce bioactive peptides from milk proteins has not been studied. The viability of the Lb. casei ATCC 393 strain and some physicochemical properties in fermented milk throughout storage for 21 days at 4 °C was evaluated; biological activity, i.e., antioxidant, angiotensin converting enzyme inhibitory and anticancer activities of water soluble extract and its filtrate (< 2 kDa; F1) were determined. Lb. casei counts remained over 9 log cfu g⁻¹ during the storage period in fermented milk. These bioactivities were increased significantly (P < 0.01) during storage. F1 of fermented milk after three weeks of storage showed the highest bioactivity impact. De novo sequencing assay for peptide identification was applied to the mass spectrum of F1. The promising capability of Lb. casei ATCC 393 to release bioactive peptides from milk proteins was demonstrated.     

The growth behaviour and enhancement of probiotic viability in bioyoghurt

The growth behaviour of Lactobacillus casei-01 and Bifidobacterium bifidum Bb-12 in bioyoghurt made with three different yoghurt starter cultures (YC-Fast 1, YC-380 and YC-180) and the enhancement of probiotic viability, were investigated. The titratable acidity (TA) increased rapidly in yoghurt samples made with YC-Fast 1. The fermentation times were 3, 3.5 and 4 h for bioyoghurts made with YC-Fast 1, YC-380 and YC-180, respectively. The total viable counts of L. casei and B. bifidum were the highest in bioyoghurt samples made with YC-180. Microencapsulation of L. casei and B. bifidum enhanced their viability and this technique can be used with normal yoghurt starter. Also, utilization of heat shock yoghurt starter enhanced the viability of probiotics.     

Survival during storage and sensory effect of potential probiotic lactic acid bacteria Lactobacillus acidophilus Bauer and Lactobacillus casei Bif3′/ IV in dry fermented pork loins

The objective of this work was to study the survival of two potential probiotic strains (Lactobacillus acidophilus Bauer and Lactobacillus casei Bif3′/IV) in pork loins both with the verification of the possibility of fermented loin development in relation to sensory and microbiological criteria. Six different samples of loins were prepared while as 3 weeks of ripening process and 6 months of storage. The obtained results indicated that highest sensory quality of fermented pork loin after storage was observed in the case of sample produced with L. acidophilus Bauer and with 0.2% glucose addition. The highest count of lactic acid bacteria was observed in the case of the sample with L. casei Bif3′/IV. The results of the study demonstrate that application of probiotic strain L. acidophilus Bauer for pork loins fermentation could assure the satisfying quality regarding sensory and microbiological criteria and can be used for dry fermented loin production.     

Probiotic viability and storage stability of yogurts and fermented milks prepared with several mixtures of lactic acid bacteria

Currently, the food industry wants to expand the range of probiotic yogurts but each probiotic bacteria offers different and specific health benefits. Little information exists on the influence of probiotic strains on physicochemical properties and sensory characteristics of yogurts and fermented milks. Six probiotic yogurts or fermented milks and 1 control yogurt were prepared, and we evaluated several physicochemical properties (pH, titratable acidity, texture, color, and syneresis), microbial viability of starter cultures (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus) and probiotics (Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus reuteri) during fermentation and storage (35 d at 5°C), as well as sensory preference among them. Decreases in pH (0.17 to 0.50 units) and increases in titratable acidity (0.09 to 0.29%) were observed during storage. Only the yogurt with S. thermophilus, L. delbrueckii ssp. bulgaricus, and L. reuteri differed in firmness. No differences in adhesiveness were determined among the tested yogurts, fermented milks, and the control. Syneresis was in the range of 45 to 58%. No changes in color during storage were observed and no color differences were detected among the evaluated fermented milk products. Counts of S. thermophilus decreased from 1.8 to 3.5 log during storage. Counts of L. delbrueckii ssp. bulgaricus also decreased in probiotic yogurts and varied from 30 to 50% of initial population. Probiotic bacteria also lost viability throughout storage, although the 3 probiotic fermented milks maintained counts ≥10⁷ cfu/mL for 3 wk. Probiotic bacteria had variable viability in yogurts, maintaining counts of L. acidophilus ≥10⁷ cfu/mL for 35 d, of L. casei for 7 d, and of L. reuteri for 14 d. We found no significant sensory preference among the 6 probiotic yogurts and fermented milks or the control. However, the yogurt and fermented milk made with L. casei were better accepted. This study presents relevant information on physicochemical, sensory, and microbial properties of probiotic yogurts and fermented milks, which could guide the dairy industry in developing new probiotic products.     

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

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

Functional cultures and health benefits

A number of health benefits have been claimed for probiotic bacteria such as Lactobacillus acidophilus, Bifidobacterium spp., and L. casei. These benefits include antimutagenic effects, anticarcinogenic properties, improvement in lactose metabolism, reduction in serum cholesterol, and immune system stimulation. Because of the potential health benefits, these organisms are increasingly being incorporated into dairy foods, particularly yoghurt. In addition to yoghurt, fermented functional foods with health benefits based on bioactive peptides released by probiotic organisms, including Evolus^® and Calpis^®, have been introduced in the market. To maximize effectiveness of bifidus products, prebiotics are used in probiotic foods. Synbiotics are products that contain both prebiotics and probiotics.     

Probiotic yoghurt functionalised with microalgae and Zedo gum: chemical,microbiological, rheological and sensory characteristics

In this study, using a central composite design, the effects of addition of Spirulina platensis and Zedo gum to plain and probiotic yoghurt samples were investigated during storage. Lactobacillus paracasei proliferation was directly dependent on the addition of microalgae and was inversely affected by storage time. Probiotic samples containing S. platensis showed the highest antioxidative activity. Maximum stability was obtained at higher amounts of Zedo gum, while organoleptic and rheological attributes improved at 0.25% Zedo gum. Given the importance of probiotic viability, supplementation of probiotic yoghurt with Zedo gum/S. platensis may be consideredas a novel nutraceutical formulation.     

Effect of lactobacillus fermented beetroot juice on composition and activity of cecal microflora of rats

This study aimed at determination of the effect caused by ingestion of beetroot juice fermented by Lactobacillus casei 0920 and Lactobacillus brevis 0944 strains on the state of cecal ecosystem of experimental rats. The intake of fermented beetroot juice containing 3.5–4.0 × 10⁹ CFU/mL live Lactobacillus sp. cells positively modulated the cecal microflora of the rats and its metabolic activity. The counts of Lactobacillus sp., Bifidobacterium sp., Bacteriodes sp., and Enterococcus sp. were maintained at the level of 8.2–8.6, 6.2–7.5, 8.0–8.3, and 7.3–7.7 log units, respectively, while the number of Clostridium sp. cells was increased by 1.1–1.6 log units and Enterobacteriaceae bacteria were reduced by 0.8–2.1 log units. In this study, the selected cecal enzymes such as β-glucosidase, β-glucuronidase, and β-galactosidase as well as the profile and concentration of short chain fatty acids (SCFA) were the biochemical markers of metabolic activity of the intestinal ecosystem. The considerable decrease in activities of β-glucosidase and β-glucuronidase was observed in all three experimental groups fed with the fermented beetroot juice. Total concentration of SCFA was the highest (78.1 μmol/100 g BW vs. 59.2 μmol/100 g BW in control group) in intestines of rats fed with 6 mL of fermented beetroot juice daily. These results prove that the fermented beetroot juice benefits cecal microbial activity.     

Conjugated linoleic acid content in fermented goat milk as affected by the starter culture and the presence of free linoleic acid

The effect of yoghurt starter cultures and probiotic Lactobacillus casei on the formation of conjugated linoleic acid (CLA) and microbial populations of fermented goat milk was investigated during 35 days of cold storage. The addition of hydrolysed sunflower oil as a source of free linoleic acid was investigated. The fermentation process enhanced the content of the cis9, trans11‐CLA isomer in milk, whereas the trans10, cis12‐CLA isomer was not detected in goat milk or control fermented milks. The use of both starters generated trans10, cis12‐CLA only when hydrolysed sunflower oil was supplemented. Populations of streptococci and lactobacilli were affected by the presence of hydrolysed sunflower oil.     

In vitro comparison of probiotic properties of Lactobacillus casei Zhang, a potential new probiotic, with selected probiotic strains

Since 2004, our research group has isolated 240 Lactobacillus strains from Koumiss, a traditional fermented alcoholic beverage prepared from mare's milk in Inner Mongolia, Xinjiang of China and Mongolia. Among these Lactobacillus strains a novel strain with potential probiotic properties, Lactobacillus casei Zhang, was screened out and studied extensively for its probiotic properties, health-promoting effects and fermentation characteristics. In vitro tests indicated that L. casei Zhang had high tolerance to simulated gastric, intestine juices and bile salts, similar to commercial probiotic strains such as Lactobacillus acidophilus NCFM, Lactobacillus rhamnosus GG, L. casei Shirota and Bifidobacterium animalis Bb12. Higher acid-production activity and proteolytic activity was observed in the fermented milk inoculated with L. casei Zhang during the refrigerated storage than in the samples inoculated with the selected commercial probiotics. The yogurt samples fermented with L. casei Zhang exhibited similarer viable count (1.0 × 10⁹ cfu/mL) as the other samples after 28 d of refrigerated storage. The results suggested that L. casei Zhang showed good potential for application in functional foods and health-related products.     

Tropical fruit pulps decreased probiotic survival to in vitro gastrointestinal stress in synbiotic soy yoghurt with okara during storage

The effect of mango and guava pulps on Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 viability in a soy yoghurt (SY) and on probiotic survival under simulated gastrointestinal conditions were investigated throughout 28 days of storage at 4 °C. The impact of fruit pulps on SY sensory acceptability was also assessed. Three formulations were produced from soymilk fermented with ABT-4 culture (La-5, Bb-12, and Streptococcus thermophilus) and supplemented with inulin and okara: SYC (control), SYM (with mango pulp), and SYG (with guava pulp). All formulations showed probiotic viabilities ranging from 8 to 9 log cfu/g, and fruit pulps did not affect the probiotic viabilities. However, the fruit pulps decreased probiotic survival significantly to simulated gastrointestinal stress. Acceptability was higher for SYM and this difference was significant at 21 days. Therefore, the improved acceptability of SY through the addition of fruit pulps might lead to a reduction in probiotic functionality.     

Use of Bacillus indicus HU36 as a probiotic culture in set‐type,recombined nonfat yoghurt production and its effects on quality

Viability of a probiotic and carotenoid‐producing bacterium, Bacillus indicus HU36 in vegetative form, along with the yoghurt cultures in set‐type, recombined nonfat yoghurt and its effects on quality were determined during the storage at 4 °C. The number of B. indicus HU36 cells in yoghurt remained about 5 log cfu/mL after 14 days, but decreased to 3.5 log after 21 days. The bacterium resulted in increased yellowness, but did not affect the rheological properties of the yoghurt. Sensorial properties of the yoghurt were acceptable compared to a commercial probiotic yoghurt. B. indicus HU36 can thus be used as a probiotic culture in yoghurt production.     

Bioactive action of β‐glucosidase enzyme of Bifidobacterium longum upon isoflavone glucosides present in soymilk

Bioconversion of isoflavone glucosides and antioxidant activity by probiotic strain (Bifidobacterium longum) during soymilk fermentation was investigated, as well as partial characterisation of the produced enzyme β‐glucosidase. The enzyme has higher affinity for genistin than for other substrates assayed. Maximum activity occurred at 42 °C and at pH 6.0; keeping 70–80% of activity for 60 days stored at low temperatures. Bifidobacterium longum grew well in soymilk (8.26 log CFU mL^?1 and pH of 3.9 at 24 h) and were produced in good quantities of organic acids. High hydrolysis degree of isoflavone glucosides (81.2%) was observed at 24 h. Enhancements in bioactivity were assessed in fermented soymilk by monitoring the radical‐scavenging activity, antioxidant activity and DNA protective action. The use of probiotic Bifidobacterium strain as β‐glucosidase producer increased bioactive isoflavone content and demonstrated that this enzyme plays a key role in the bioavailability of soymilk isoflavones, reducing the bioconversion time compared to other studies.     

Physico-Chemical,antioxidant activities,textural, and sensory properties of yoghurt fortified with different states and rates of pomegranate seeds (Punica granatum L.)

This study examines the effects of incorporating fresh, frozen, osmodehydrated, and dried pomegranate seeds, at different concentrations (5, 10, and 20%) on the physicochemical, antioxidant, textural, and sensory properties of yoghurt. Antioxidant activity, pH, acidity, syneresis, and color of yoghurt were also evaluated during the storage (28 days) at 4°C. The principal component analysis (PCA) was performed to assess the correlations between different yoghurt formulation and their sensory attributes. Data showed that the addition of pomegranate seeds reduced pH and modified the chromatics coordinate (L*, a*, b*, C*, h°) and firmness of the yoghurt samples. In addition, acidity, °Brix, and syneresis increased compared to the control. Thanks to their high anthocyanin content, pomegranate seeds considerably improved the antioxidant activity essentially for yoghurt enriched with frozen seeds. In addition, the supplementation of 20% of frozen seeds into yoghurt was the most appreciated by panelists and improved the sensory properties in comparison to other formulation. According to PCA, taste and appearance were the main criteria for the overall acceptability of yoghurt. After 28 days of storage, the reddish color was reinforced; however, the antioxidant activity of yoghurts was reduced. Overall, it can be concluded that pomegranate seeds can be used as a natural ingredient to develop a novel yoghurt with high nutritional properties.     

Encapsulation in an alginate–goats’ milk–inulin matrix improves survival of probiotic Bifidobacterium in simulated gastrointestinal conditions and goats’ milk yoghurt

In this work, a new encapsulating matrix, alginate–goats’ milk–inulin, was used to encapsulate Bifidobacterium animalis subsp. lactis BB‐12. The addition of inulin resulted in capsules with a compact structure, and a higher probiotic cell count under simulated gastrointestinal conditions and in probiotic goats’ milk yoghurt during refrigerated storage. Encapsulation of the probiotic bacteria led to slower post‐acidification yoghurts. The results of this study showed that the alginate–goats’ milk–inulin matrix has potential to be used as a new encapsulation material to encapsulate probiotics for use in goats’ milk‐based probiotic fermented dairy products, avoiding the cross‐contamination caused by using capsules based on cows’ milk.