Yoghurt added with Lactobacillus casei and sweetened with natural sweeteners and/or prebiotics: Implications on quality parameters and probiotic survival

The effect of addition of natural sugar substitutes (stevia, erythritol or xylitol) and prebiotics (oligofructose or polydextrose) on physicochemical characteristics, probiotic survival (Lactobacillus casei) and sensory acceptance of yoghurts during storage (7 °C, 28 days) was evaluated. Yoghurts with sucrose or sucralose were also prepared. Xylitol and sucralose added yoghurts had physicochemical characteristics and sensory acceptance similar to those of the product with sucrose. Xylitol was more efficient in maintenance of textural characteristics and probiotic survival in simulated gastrointestinal conditions (SGIC) than sucralose. Addition of erythritol and stevia changed the textural parameters, reduced acceptance and decreased probiotic survival in SGIC. Addition of oligofructose or polydextrose improved texture and increased probiotic survival but decreased flavour acceptance. All formulations could be considered probiotic products during shelf life (7 °C, 28 days) with counts higher than 10⁷ cfu mL⁻¹ in the product and 10⁴ cfu mL⁻¹ after SGIC.     

Optimization of the Fermentation of Cantaloupe Juice by Lactobacillus casei NRRL B-442

This study was carried out to optimize the fermentation pH and temperature and also the fermentation time for development of a new probiotic fermented drink with cantaloupe juice. The fermented juice was subjected to a storage study during 42?days at 4?°C. The initial pH and temperature influenced the growth of Lactobacillus casei in cantaloupe juice. However, on the microbial viability only the effect of temperature was significant. Optimum conditions for a satisfactory growth and viability of L. casei in cantaloupe juice were as follows: pH?=?6.1 and temperature?=?31?°C. The fermentation time of 8 hours was selected as the optimal fermentation time to prepare the probiotic cantaloupe juice. The cell viability was 8.3 log CFU mL^?1 at the end of the fermentation. This level was kept over the 42?days of refrigerated storage. The consistent growth and viability of the probiotic microorganism in cantaloupe juice during fermentation and storage suggested that melon is a suitable vehicle for L. casei delivering. The fermented juice arises as a good alternative to the traditional dairy based products.     

Characteristics of carbonated fermented milk and survival of probiotic bacteria

The carbonation of pasteurised milk was evaluated as a method for improving bacterial viability in fermented milk added with probiotic bacteria (Lactobacillus acidophilus and/or Bifidobacterium bifidum). The behaviour of microorganisms during fermentation and cold storage, and the biochemical and sensory properties of the products were assessed. In AT (Streptococcus thermophilus/L. acidophilus) and ABT (S. thermophilus/L. acidophilus/B. bifidum) products, the fermentation times to decrease the pH to 5 were significantly lowered when CO₂ or lactic acid was added to milk. The higher acidity levels of carbonated (as a result of production of carbonic acid) and lactic acidified samples enhanced growth and metabolic activity of the starter during fermentation and was the reason for this reduction in incubation time. Cell counts of S. thermophilus, L. acidophilus and B. bifidum gradually decreased through the cold storage of carbonated and non-acidified fermented milk, although the counts were always higher than 10⁶ viable cells g⁻¹. The CO₂ did not exert any influence on the viability of S. thermophilus and L. acidophilus in AT fermented milk stored at 4°C but the presence of B. bifidum and CO₂ in ABT-type products was associated with lower viability of L. acidophilus during the refrigerated storage. The higher acetate concentrations of ABT products made with non-acidified milk as compared with the carbonated products could have contributed to major survival of L. acidophilus in the former. The use of milk acidified with CO₂ had no detrimental effects on the sensory properties of ABT fermented milk. Therefore, we concluded that the carbonation of pasteurised milk prior to the starter addition could be satisfactorily used to reduce the manufacture time of fermented milk.     

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.     

Non-conventional fermentation at laboratory scale of cocoa beans: Using probiotic microorganisms and substitution of mucilage by fruit pulps

In a non-conventional lab-scale fermentation of cocoa beans using probiotic microorganisms and substituting the cocoa pulp for fruit pulp, physicochemical, microbiological and quality parameters were investigated. Two hundred grams of beans were fermented in a controlled environmental chamber (temperature ramp rate of 25°C for 48 h; 35°C for 48 h and 45°C for 48 h; and 65% HR). pH, titratable acid, citric, lactic and acetic acids, as well as sugars and ethanol were measured. A cut test was also performed on the cocoa beans fermented 5 and 6 days. As the fermentation time progressed, citric acid concentration decreased until 0.53 g kg⁻¹, whereas both lactic and acetic acids increased until 0.44 and 16.58 g kg⁻¹, respectively. Sucrose content decreased from 12.26 g kg⁻¹ (in fresh) to 6.54 g kg⁻¹ on the 6th day. Fructose and glucose contents increased in the cotyledons from day five, reaching a maximum concentration of 1.14 and 1.01 g kg⁻¹, respectively, on day six. Yeasts were the main microorganisms during the first 24–48 h (8.4 log CFU g⁻¹), while bacterial counts reached its highest number (7.8 log CFU g⁻¹) on day four. Beans fermented 5 and 6 days resulted in more fermented beans (>81%) and less violet ones (<18.4%) than the control.     

Development of a new oat-based probiotic drink

In the present work, a whole-grain oat substrate was fermented with lactic acid bacteria to obtain a drink, combining the health benefits of a probiotic culture with the oat prebiotic beta-glucan. The levels of several factors, such as starter culture concentration, oat flour and sucrose content, affecting the fermentation process, were established for completing a controlled fermentation for 8 h. The viable cell counts reached at the end of the process were about 7.5 x 10(10) cfu ml(-1). It was found that the addition of sweeteners aspartame, sodium cyclamate, saccharine and Huxol (12% cyclamate and 1.2% saccharine) had no effect on the dynamics of the fermentation process and on the viability of the starter culture during product storage. Beta-glucan content in the drink (0.31-0.36%) remained unchanged both throughout fermentation and storage of the drink. The shelf life of the oat drink was estimated to 21 days under refrigerated storage.     

Potato juice fermented with Lactobacillus casei as a probiotic functional beverage

This study was conducted to evaluate probiotic potato juice as a potential substrate for the production of Lactobacillus casei, and the change in the functionality of potato juice was monitored during fermentation. L. casei grew well in potato juice without nutrient supplementation, and lactic acid bacteria of fermented ‘Haryoung’ juice reached 1.7×10⁹ CFU/mL after a 48 h fermentation. DPPH radical scavenging activities of the potato juices decreased after a 72 h fermentation, but fermented colored potato juice still maintained >50% radical scavenging activity. The survival rate of L. casei fermented in’ Haryoung’ juice was 89.0% after exposure to an acidic condition, and L. casei in all fermented potato juice samples showed the ability (50–85%) to survive in the presence of bile. These results suggest that fermented potato juice might serve as a probiotic functional beverage for vegetarians or consumers who are allergic to dairy products.     

Evaluation of the composition and quality of watermelon and mango juices fermented by Levilactobacillus brevis,Lacticaseibacillus casei and Pediococcus pentosaceus and subsequent simulated digestion and storage

This study evaluated the composition of watermelon and mango juices fermented by Levilactobacillus (L.) brevis, Lacticaseibacillus (La.) casei and Pediococcus (P.) pentosaceus and subsequently simulated in vitro digestion and storage (4°C for 35 days). After fermentation (24 h), the microorganisms grew (~9 log CFU mL⁻¹) and fermented watermelon (FWJ) and mango juice (FMJ) became more red and yellow, respectively. DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) free radical scavenging capacities significantly increased in L. brevis and La. casei FMJ. After in vitro digestion, all the strains except La. casei in FMJ significantly decreased (P < 0.05), and P. pentosaceus survival was 2.4 and 4.5 times higher in FWJ and FMJ, respectively, than as pure culture. After storage, cell counts remained above 7 log CFU mL⁻¹, and no changes in quality attributes, total phenolic content and antioxidant capacity were recorded in P. pentosaceus FMJ. Thus, watermelon and mango are suitable matrices for lactic acid bacteria.     

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.     

Effect of milk supplementation and culture composition on acidification, textural properties and microbiological stability of fermented milks containing probiotic bacteria

In the present work, the combined effect of milk supplementation and culture composition on acidification, textural properties, and microbiological stability of fermented milks containing probiotic bacteria, was studied. Three powders (whey, casein hydrolysate, and milk proteins) were tested as supplementation. Two strains of probiotic bacteria, Lactobacillus acidophilus (LA5) and Lactobacillus rhamnosus (LC35), were used in pure culture, and in mixed culture with Streptococcus thermophilus (ST7). Acidifying activity was enhanced with mixed cultures, compared to pure cultures resulting in a shorter time to reach pH 4.5. Acidifying activity was greatly improved with casein hydrolysate, with a reduction of the fermentation time by about 55% by comparison with the other supplementations. The stability of probiotic bacteria was weakly affected by milk supplementation and culture composition. However, pure cultures were more stable than mixed cultures. The texture of the fermented products was not dependent on culture composition, but strongly dependent on milk supplementation. Sweet whey supplementation gave products with lower firmness and viscoelasticity than products supplemented with casein hydrolysate or milk proteins (decrease by 70%). It was observed that all products containing probiotic counts over 2.2×10⁷ CFU mL⁻¹ are suitable for the development of a lactic beverage containing probiotics.     

Microbiological attributes and biogenic amine content of probiotic Turkish fermented sausage

Microbiological attributes and biogenic amine content of Turkish fermented sausage manufactured by using probiotic starter cultures (Lactobacillus casei, L. acidophilus or their combination) were investigated before and after fermentation-drying period and during refrigerated storage at 4?±?1?°C for 8?months at 2?month intervals. As results of the study, during fermentation and storage biogenic amine content (histamine, putrescine, cadaverine and tyramine) of the samples were increased significantly. Salmonella, Staphylococcus aureus, coliform and fecal coliform microorganisms were not detected during fermentation and storage. Probiotic microorganism counts of all samples were higher than the lower limit of 6.0 log cfu/g which is requested for probiotic foods.     

Microbiological attributes and biogenic amine content of probiotic Turkish fermented sausage

Microbiological attributes and biogenic amine content of Turkish fermented sausage manufactured by using probiotic starter cultures (Lactobacillus casei, L. acidophilus or their combination) were investigated before and after fermentation-drying period and during refrigerated storage at 4 ± 1 °C for 8 months at 2 month intervals. As results of the study, during fermentation and storage biogenic amine content (histamine, putrescine, cadaverine and tyramine) of the samples were increased significantly. Salmonella, Staphylococcus aureus, coliform and fecal coliform microorganisms were not detected during fermentation and storage. Probiotic microorganism counts of all samples were higher than the lower limit of 6.0 log cfu/g which is requested for probiotic foods.     

牛羊乳促嗜酸乳杆菌增菌发酵差异性及冷藏存活率比较研究

益生菌的活菌数量是衡量益生菌产品及制剂的营养价值和保健功能的主要指标之一。本研究以嗜酸乳杆菌为发酵剂分析比较牛乳发酵奶和羊乳发酵奶中嗜酸乳杆菌增菌发酵的活力差异,及在冷藏期活菌数量的变化趋势,探讨了牛羊乳在促进嗜酸乳杆菌发酵方面的差异性及在冷藏期存活率变化规律。结果表明:嗜酸乳杆菌在羊乳基质中表现为较好的增菌发酵效能,总活菌数为1.66×1010CFU/mL,大于牛乳基质中的总活菌数3.02×109CFU/mL;羊乳发酵奶和牛乳发酵奶在21d贮藏期内嗜酸乳杆菌的活菌数均维持在较高活力水平,而在21～26d的贮藏期内,其存活性显著降低(p<0.05),存活率分别为84.15%和84.39%。由此说明羊乳基质促嗜酸乳杆菌增菌发酵效能更佳,牛、羊乳发酵奶在贮藏期活菌数变化规律基本一致。     

Effect of microencapsulation and resistant starch on the probiotic survival and sensory properties of synbiotic ice cream

Two types of synbiotic ice cream containing 1% of resistant starch with free and encapsulated Lactobacillus casei (Lc-01) and Bifidobacterium lactis (Bb-12) were manufactured. The survival of L. casei and B. lactis were monitored during the product’s storage for 180 days at −20 °C. The viable cell number of L. casei and B. lactis in the free state in prepared ice cream mixture was 5.1 × 10⁹ and 4.1 × 10⁹ CFU/mL at day one and after 180 days storage at −20 °C, these numbers were decreased to 4.2 × 10⁶ and 1.1 × 10⁷ CFU/mL, respectively. When we encapsulated the mentioned probiotic bacteria in calcium alginate beads, the probiotic survival raised at rate of 30% during the same period of storage at same temperature. In general, the results indicated that encapsulation can significantly increase the survival rate of probiotic bacteria in ice cream over an extended shelf-life. The addition of encapsulated probiotics had no significant effect on the sensory properties of non-fermented ice cream in which we used the resistant starch as prebiotic compound.     

Mixed fermentation of jujube juice (Ziziphus jujuba Mill.) with L. rhamnosus GG and L. plantarum-1: effects on the quality and stability

This study was conducted aiming at improving the quality of jujube juice by mixed fermentation of lactobacilli. Selection of favourable lactobacilli and addition of nitrogen sources were explored as an efficient method to improve the viability of probiotic in jujube juice. After fermentation, the viability increased to 9.15 ± 0.10 Log CFU mL⁻¹, while the content of lactic acid increased to 5.61 ± 0.03 mg mL⁻¹. The total phenolic and total flavonoid content were 2663.03 ± 11.95 μg mL⁻¹ and 163.95 ± 0.47 μg mL⁻¹ respectively. Moreover, the stability of fermented jujube juice during refrigeration was investigated, which showed that the viability dropped to 8.84 ± 0.6 Log CFU mL⁻¹ and the concentration of lactic acid slowly increased to 6.51 ± 0.04 mg mL⁻¹; the ABTS value showed a 4.26% reduction and FRAP value did not significantly (P < 0.05) change during refrigerated storage. In addition to the existing knowledge, our data aid to the future applications of the jujube as a potential ingredient in novel probiotic foods formulation.     

Application of pure and mixed probiotic lactic acid bacteria and yeast cultures for oat fermentation

Fermentation of a prebiotic containing oat substrate with probiotic lactic acid bacteria and yeast strains is an intriguing approach for the development of new synbiotic functional products. This approach was applied in the present work by using pure and mixed microbial cultures to ferment a heat‐treated oat mash. Results show that the strains studied were appropriate for oat fermentation and the process could be completed for 6–10 h depending on the strain. The viable cell counts achieved within this time were above the required levels of 10⁶–10⁷ cfu ml⁻¹ for probiotic products. Both single lactic acid bacteria strains and mixed cultures of the same strains with yeast were found suitable for oat fermentation. However, the pure LAB cultures attributed better flavour and shelf life of the oat drinks. The content of the prebiotic oat component beta‐glucan remained within 0.30–0.36% during fermentation and storage of the drinks obtained with each of the strains used. Thus, these products would contribute diet with the valuable functional properties of beta‐glucan. Also, the viability of pure and mixed cultures in the oat products was good: levels of cell counts remained above the required numbers for probiotic products throughout the estimated shelf‐life period. Copyright © 2005 Society of Chemical Industry     

Effect of Greek-style yoghurt manufacturing processes on starter and probiotic bacteria populations during storage

This study compared viable counts of Streptococcus thermophilus (starter) and Lactobacillus helveticus R0052 (probiotic), as a function of two manufacturing processes of Greek-style (GS) yoghurt: centrifugation of a curd (GS-CF process) or ultrafiltration of milk prior to fermentation (GS-UF process). Fresh GS-UF and GS-CF yoghurts had between 3 and 7 times higher counts of Lb. helveticus R0052 and S. thermophilus than the regular stirred yoghurt (Control). Strain R0052 was three times more stable in the GS-CF yoghurt than in the Control over the 44 d storage period. The highest lactose content (44 g L⁻¹) was obtained in the Control, while 60% less was obtained in the GS-UF yoghurt; the opposite trend was observed for lactic acid and galactose. Free amino acid levels were 33% higher in the GS products. GS yoghurt can be 10 times better than traditional yoghurt to deliver probiotic bacteria, as a function of the process used.     

Fermented coconut jelly as a probiotic vehicle,physicochemical and microbiology characterisation during an in vitro digestion

There is little information on the survival of probiotics in plant-based foods after simulated gastric and intestinal conditions, likewise the microstructure arrangement in the no-dairy fermented food. This work aimed to study if the agar–agar in a fermented coconut jelly confers protection to probiotics, phenolic and antioxidant compounds during in vitro digestion. Samples containing higher agar–agar amounts tend to retain (P < 0.05) antioxidant and phenolic compounds in their network better, even after the in vitro digestion. Also, a compact and homogeneous microstructure was observed by the Confocal Laser Scanning Microscopy. The texture profile analysis shows that 1% of agar samples presented the maximum hardness (P < 0.05) due to more bonding points and intermolecular interactions. Finally, the survival of probiotics remained above the recommended values (10⁶–10⁷ CFU g⁻¹) after the in vitro digestion of a product with probiotic potential.     

Viability assessment of lactic acid bacteria in commercial dairy products stored at 4 °C using LIVE/DEAD® BacLightTM staining and conventional plate counts

The viability of lactic acid bacteria (LAB) from commercial fermented milks was studied during storage at 4 °C. The enumeration of total viable bacteria was assessed using fluorescence microscopy. Plate counting on selective media was used to enumerate LAB. Using LIVE/DEAD® BacLight^TM viability staining, it was observed that bacterial counts decreased gradually after expiry dates, the number of viable bacteria remaining above 10⁶ bacteria g^?1 for all of the products. Viable cell counts estimated by plating onto selective media were lower than those obtained by direct microscopic counting. The viability of LAB contained in acid products decreased during their storage period at 4 °C. All products contain viable LAB ranging from 10⁸ to 10⁹ bacteria g^?1 and could be considered as probiotic, given that the recommended minimum number of probiotic bacteria in such food products is approximately 10⁷ bacteria mL^?1 product. The number of bifidobacteria in commercial fermented milks declared to contain bifidobacteria varied from 10⁴ to 10⁷ bacteria mL^?1. This study confirms the usefulness of fluorescent techniques for a rapid and accurate evaluation of bacterial viability in probiotic products.     

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.