Short communication: Incorporation of inulin and transglutaminase in fermented goat milk containing probiotic bacteria

Goat milk is a good carrier for probiotic bacteria; however, it is difficult to produce fermented goat milk with a consistency comparable to that of fermented cow milks. It can be improved by the addition of functional stabilizers, such as inulin, or treatment with transglutaminase. The aim of this study was to determine the effect of cold storage of inulin and microbial transglutaminase on the viability of Lactobacillus acidophilus La-5 and Bifidobacterium animalis ssp. lactis Bb-12 in fermented goat milk. Microbiological analysis included the determination of the probiotic bacteria cell count in fermented milk samples, whereas physico-chemical analysis included the analysis of fat content, titratable acidity, and pH of raw, pasteurized, and fermented goat milk samples. No positive influence of inulin or microbial transglutaminase on the viability of probiotics in fermented goat's milk samples was observed. Nevertheless, the population of probiotics remained above 6 log cfu/g after 8 wk of storage at 5°C.     

Effect of buckwheat flour and oat bran on growth and cell viability of the probiotic strains Lactobacillus rhamnosus IMC 501®, Lactobacillus paracasei IMC 502® and their combination SYNBIO®, in synbiotic fermented milk

Fermented foods have a great significance since they provide and preserve large quantities of nutritious foods in a wide diversity of flavors, aromas and texture, which enrich the human diet. Originally fermented milks were developed as a means of preserving nutrients and are the most representatives of the category. The first aim of this study was to screen the effect of buckwheat flour and oat bran as prebiotics on the production of probiotic fiber-enriched fermented milks, by investigating the kinetics of acidification of buckwheat flour- and oat bran-supplemented milk fermented by Lactobacillus rhamnosus IMC 501®, Lactobacillus paracasei IMC 502® and their 1:1 combination named SYNBIO®. The probiotic strains viability, pH and sensory characteristics of the fermented fiber-enriched milk products, stored at 4 °C for 28 days were also monitored. The results showed that supplementation of whole milk with the tested probiotic strains and the two vegetable substrates results in a significant faster lowering of the pH. Also, the stability of L. rhamnosus IMC 501®, L. paracasei IMC 502® and SYNBIO® during storage at 4 °C for 28 days in buckwheat flour- and oat bran-supplemented samples was remarkably enhanced. The second aim of the study was to develop a new synbiotic product using the best combination of probiotics and prebiotics by promoting better growth and survival and be acceptable to the consumers with high concentration of probiotic strain. This new product was used to conduct a human feeding trial to validate the fermented milk as a carrier for transporting bacterial cells into the human gastrointestinal tract. The probiotic strains were recovered from fecal samples in 40 out of 40 volunteers fed for 4 weeks one portion per day of synbiotic fermented milk carrying about 10⁹ viable cells.     

The effects of consuming probiotic‐fermented milk on the immune system: A review of scientific evidence

Fermented dairy products are commonly used as the most efficient delivery vehicle for probiotics. These foods are well known for promoting the positive health benefits of consuming probiotics. Among their beneficial effects, their immunomodulatory properties have attracted a great deal of interest in recent years. Reports, both in vitro and in vivo, on the beneficial effects of consuming fermented milks containing probiotics have demonstrated the enhancement of various parameters in animal (e.g. rats and mice) and human immune systems, such as the production of cytokines and mediators by antigen‐presenting cells and cellular markers for different cell populations. Hence, the purpose of this review was to provide an overview of the scientific literature concerning the potential of probiotic‐fermented milks to influence the host's immune system, thereby modulating the immune response in a positive fashion.     

Review Article: Technological Aspects of Prebiotics in Probiotic Fermented Milks

Prebiotics are food components that exert beneficial effects on health of the host, associated with modulation of the intestinal flora via stimulating the growth and/or activity of the probiotics. One of the recommended ways to maintain high viable numbers of probiotic bacteria in the intestine as well as in the probiotic fermented milk products until the time of consumption is via the use of prebiotics. These compounds can also affect sensory profile, physicochemical and rheological characteristics, and economic properties of probiotic fermented milk products. In this article, technological aspects of prebiotics (viability of probiotics in the product as well as the physicochemical, rheological, sensory, and economic characteristics of product) in probiotic fermented milks are reviewed.     

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.     

An Influence of Fructan Containing Concentrate from Jerusalem Artichoke Tubers on the Development of Probiotic Dairy Starters on Milk and Oat-based Substrates

Supplementation of milk and oat hydrolysate containing medium with Jerusalem artichoke concentrate (JAC) and subsequent fermentation with probiotic dairy starters resulted in substantial stimulation of probiotics Bifidobacterium lactis and Lactobacillus acidophilus as well as yogurt starter culture Lactobacillus bulgaricus development and acidification rate. The strain-specific responses of the general yogurt cultures, as well as probiotics to the addition of JAC, should be considered to achieve optimal composition of probiotic strains and conformable fermentation conditions. JAC is suggested to be perspective prebiotic additive for fermented synbiotic milks or oat-hydrolysate-based products.     

Effects of Chlorella vulgaris and Arthrospira platensis addition on viability of probiotic bacteria in yogurt and its biochemical properties

It is a practice to add microalgae into plain and probiotic fermented milks in order to promote the functionality of these products via their direct health effects as well as the enhancing impact on viability of probiotic microorganisms in product and in gastrointestinal tract. In this study, the effects of addition of two species of microalgae including Arthrospira platensis and Chlorella vulgaris (seven yogurt treatments containing three concentrations for each microalgae—0.25, 0.50, and 1.00?%—and a control without microalgae) on pH, titrable acidity, and redox potential changes as well as on the viability of probiotic bacteria during fermentation and during a 28-day refrigerated storage period (5?°C) were investigated in yogurt. Also, the amounts of lactic and acetic acids at the end of fermentation were assessed. The culture composition of yogurt was ABY type, containing Lactobacillus acidophilus LA-5, Bifidobacterium lactis BB-12, Lactobacillus delbrueckii ssp. bulgaricus, and Stresptococcus themophilus. The addition of microalgae significantly (p?<?0.05) increased the viability of L. acidophilus and bifdobacteria at the end of fermentation and during the storage period. Treatments containing A. platensis had slower pH decline, faster acidity increase, longer incubation time, and greater final titrable acidity than those containing C. vulgaris and control. In treatments containing 0.5 or 1?% microalgae, the viability was almost higher than 10⁷ cfu/mL until the end of refrigerated storage.     

Viability of probiotic bacteria in fermented skim milk produced with different levels of milk powder and sugar

In this work, the effect of skim milk powder (0, 5%, 10%, 15% w/v) and sugar (0%, 10% w/v) on the viability of probiotic micro‐organisms and on the quality of fermented milks was investigated. Fermented milks were submitted to physicochemical, microbiological and sensory analyses on the 1st, 10th and 21st days after production. Sugar inclusion did not affect the probiotic growth in fermented milks, but milk powder levels of 10–15% influenced positively the probiotic counts, which were above six log colony‐forming units (cfu)/g. These findings can be useful for small dairy industries that are interested in producing flavoured fermented milks without decreasing the viability of probiotic micro‐organisms during its shelf life.     

Probiotics and prebiotics--perspectives and challenges

Owing to their health benefits, probiotics and prebiotics are nowadays widely used in yogurts and fermented milks, which are leader products of functional foods worldwide. The world market for functional foods has grown rapidly in the last three decades, with an estimated size in 2003 of ca US$ 33 billion, while the European market estimation exceeded US$ 2 billion in the same year. However, the production of probiotics and prebiotics at industrial scale faces several challenges, including the search for economical and abundant raw materials for prebiotic production, the low-cost production of probiotics and the improvement of probiotic viability after storage or during the manufacturing process of the functional food. In this review, functional foods based on probiotics and prebiotics are introduced as a key biotechnological field with tremendous potential for innovation. A concise state of the art addressing the fundamentals and challenges for the development of new probiotic- and prebiotic-based foods is presented, the niches for future research being clearly identified and discussed.     

Influence of addition of raffinose family oligosaccharides on probiotic survival in fermented milk during refrigerated storage

The influence of the addition of raffinose family oligosaccharides (RFOs) extracted from lupin seeds on the survival of Bifidobacterium lactis Bb-12 and Lactobacillus acidophilus La-5 in fermented milk during 21 days of storage in refrigerated conditions was studied. For this purpose, viability and metabolic activity (expressed as pH, lactic and acetic acid production and utilization of soluble carbohydrates) of probiotic bacteria were determined. Retention of viability of B. lactis Bb-12 and L. acidophilus La-5 was greater in fermented milk with RFOs. The pH of probiotic fermented milk at 21 days of storage was lower (4.27) compared with probiotic fermented milk with RFOs (4.37). The highest levels of lactic and acetic acid were produced in probiotic fermented milk without RFOs compared with probiotic fermented milk with RFOs during storage at 4 °C. Soluble carbohydrates were utilised in fermented milk with and without RFOs, respectively, for maintaining B. lactis Bb-12 and L. acidophilus populations during refrigerated storage. In conclusion, all these experiments provide convincing evidence that RFOs have beneficial effects on the survival of these probiotic cultures in dairy products. As a result, such stored dairy products containing both probiotics and prebiotics have synergistic actions in the promotion of health.     

EFFECT OF COLD STORAGE ON CULTURE VIABILITY AND SOME RHEOLOGICAL PROPERTIES OF FERMENTED MILK PREPARED WITH YOGURT AND PROBIOTIC BACTERIA

ABSTRACT

We examined the effect of storage time on culture viability and some rheological properties (yield stress, storage modulus, loss modulus, linear viscoelastic region, structural recuperation and firmness) of fermented milk made with Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus acidophilus (LA) and Bifidobacterium animalis ssp. lactis in coculture with Streptococcus thermophilus (ST). Acidification profiles and factors that affect viability (postfermentation acidification, acidity and dissolved oxygen) were also studied during 35 days at 4C. Fermented milk prepared with a coculture of ST and Bifidobacterium lactis gave the most constant rheological behavior and the best cell viability during cold storage; it was superior to ST plus LA for probiotic fermented milk production.

PRACTICAL APPLICATIONS

Probiotic cultures should grow quickly in milk, provide adequate sensory and rheological properties to the product, and remain viable during storage. Commercially, it is very common to use yogurt starter culture (i.e. Streptococcus thermophilus[ST] and Lactobacillus delbrueckii ssp. bulgaricus) in combination with the probiotic bacteria in order to reduce fermentation time. However, LB tends to post acidify fermented milk, which reduces the viability of the probiotic bacteria; thus, it is recommended to use starter cultures devoid of this species. We found that the technological properties and the viability of the probiotic bacterium Bifidobacterium animalis ssp. lactis BL O4 in coculture with ST make it suitable for probiotic fermented milk production; it produces rheological characteristics similar to those of yogurt.     

Short communication: Survival of the characteristic microbiota in probiotic fermented camel,cow, goat,and sheep milks during refrigerated storage

The objective of this study was to monitor the viability during storage of Lactobacillus acidophilus LA-5 (A), Bifidobacterium animalis ssp. lactis BB-12 (B), and Streptococcus thermophilus CHCC 742/2130 (T) in probiotic cultured dairy foods made from pasteurized camel, cow, goat, and sheep milks fermented by an ABT-type culture. The products manufactured were stored at 4°C for 42 d. Microbiological analyses were performed at weekly intervals. Streptococcus thermophilus CHCC 742/2130 was the most numerous culture component in all 4 products both at the beginning and at the end of storage. The viable counts of streptococci showed no significant decline in fermented camel milk throughout the entire storage period. The initial numbers of Lb. acidophilus LA-5 were over 2 orders of magnitude lower than those of Strep. thermophilus CHCC 742/2130. With the progress of time, a slow and constant decrease was observed in lactobacilli counts; however, the final viability percentages of this organism did not differ significantly in the probiotic fermented milks tested. The cultured dairy foods made from cow, sheep, and goat milks had comparable B. animalis ssp. lactis BB-12 counts on d 0, exceeding by approximately 0.5 log₁₀ cycle those in the camel milk-based product. No significant losses occurred in viability of bifidobacteria in fermented camel, cow, and sheep milks during 6 wk of refrigerated storage. In conclusion, all 4 varieties of milk proved to be suitable raw materials for the manufacture of ABT-type fermented dairy products that were microbiologically safe and beneficial for human consumption. It was suggested that milk from small ruminants be increasingly used to produce probiotic fermented dairy foods. The development of camel milk-based probiotic cultured milks appears to be even more promising because new markets could thus be conquered. It must be emphasized, however, that further microbiological and sensory studies, technology development activities, and market research are needed before such food products can be successfully commercialized.     

Optimisation of probiotic yoghurt production containing Zedo gum

A Box‐Behnken design was applied to optimise the viability of Lactobacillus acidophilus and Bifidobacterium bifidum in probiotic yoghurt containing a novel exudative Zedo gum. The effect of incubation temperature, probiotic inoculation rate, storage time and Zedo gum concentration on quality indices of the yoghurt were explored. With respect to probiotics viability, probiotic inoculation rate was the most important factor followed by the storage time. Zedo gum did not show any significant effect on probiotics viability. The optimum conditions of probiotic yoghurt production were as follows: probiotic inoculation level, 12.8 g/100 kg of milk; incubation temperature, 41.6 °C; and Zedo gum concentration, 0.13%.     

益生菌发酵乳低温酸性双重胁迫致益生菌损伤 机制的研究进展

益生菌是一类对宿主有益的活性微生物,是定植于人体肠道、生殖系统内,能产生确切健康功效从而改善宿主微生态平衡、发挥有益作用的活性有益微生物的总称。近年,有关益生菌发酵乳中低温酸性双胁迫致益生菌的损伤,发酵乳中益生菌活性的保护,以及组学技术推动下的菌株损伤相关代谢研究取得了一定进展。本文综述了益生菌低温酸性双胁迫下损伤应激和保护机制、菌株特性对发酵乳风味和质量的影响及益生菌发酵乳冷藏过程低温酸性双重胁迫下菌体活性的保护策略,为研究影响益生菌发酵乳中益生菌存活能力、菌体细胞膜特性及代谢酶活性的因素,明确益生菌发酵乳基质中益生菌低温酸性双胁迫损伤的分子机制,建立益生菌发酵乳加工和贮藏过程中益生菌的保护策略提供参考,也为未来改善益生菌发酵乳的功效和品质提供了科学依据。     

Fatty acid profile, trans-octadecenoic, α-linolenic and conjugated linoleic acid contents differing in certified organic and conventional probiotic fermented milks

Development of dairy organic probiotic fermented products is of great interest as they associate ecological practices and benefits of probiotic bacteria. As organic management practices of cow milk production allow modification of the fatty acid composition of milk (as compared to conventional milk), we studied the influence of the type of milk on some characteristics of fermented milks, such as acidification kinetics, bacterial counts and fatty acid content. Conventional and organic probiotic fermented milks were produced using Bifidobacterium animalis subsp. lactis HN019 in co-culture with Streptococcus thermophilus TA040 and Lactobacillus delbrueckii subsp. bulgaricus LB340. The use of organic milk led to a higher acidification rate and cultivability of Lactobacillus bulgaricus. Fatty acids profile of organic fermented milks showed higher amounts of trans-octadecenoic acid (C18:1, 1.6 times) and polyunsaturated fatty acids, including cis-9 trans-11, C18:2 conjugated linoleic (CLA-1.4 times), and α-linolenic acids (ALA-1.6 times), as compared to conventional fermented milks. These higher levels were the result of both initial percentage in the milk and increase during acidification, with no further modification during storage. Finally, use of bifidobacteria slightly increased CLA relative content in the conventional fermented milks, after 7 days of storage at 4 °C, whereas no difference was seen in organic fermented milks.     

Probiotic potential and biochemical and technological properties of Lactococcus lactis ssp. lactis strains isolated from raw milk and kefir grains

Lactococcus lactis ssp. lactis is one of the most important starter bacteria used in dairy technology and it is of great economic importance because of its use in the production of dairy products, including cheese, butter, cream, and fermented milks. Numerous studies have evaluated the biochemical and probiotic properties of lactococci; however, limited studies on the probiotic characteristics of lactococci were conducted using strains originating from raw milk and dairy products. Characterizing the probiotic properties of strains isolated from raw milk and fermented milk products is important in terms of selecting starter culture strains for the production of functional dairy products. In this study, biochemical properties (including antibiotic sensitivity, lipolytic activity, amino acid decarboxylation, antioxidant activity) and probiotic properties (including antimicrobial activity, growth in the presence of bile salts, bile salts deconjugation, and hydrophobicity) of 14 Lactococcus lactis strains isolated from raw milk and kefir grains were investigated. Strains originating from kefir grains had better characteristics in terms of antimicrobial activity and bile salt deconjugation, whereas strains from raw milk had better hydrophobicity and antioxidant activity characteristics. None of the strains were able to grow in the presence of bile salt and did not show amino acid decarboxylation or lipolytic activities. Biochemical and probiotic properties of L. lactis strains varied depending on the strain and some of these strains could be used as functional cultures depending on their properties. However, these strains did not possess all of the properties required to meet the definition of a probiotic.     

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.     

益生菌的功效与潜在危害

过去20年里,益生菌被广泛应用于食品中,尤其是发酵乳品中。在筛选益生菌时,其安全性、功能性和加工特性是必须考虑的方面。益生菌对免疫活性宿主是有益的,但是对免疫缺陷宿主,却可能产生危害。一些益生菌与条件感染有关,并且还有传递抗抗生素基因的危险。     

Incorporation of citrus fibers in fermented milk containing probiotic bacteria

The incorporation of Lactobacillus acidophilus CECT 903, Lactobacillus casei CECT 475 and Bifidobacterium bifidum CECT 870 together with lemon (LF) and orange (OF) fibers obtained from juice by-products were tested in (i) a model system: fiber enriched with de Man Rogosa Sharp (MRS) broth cultured with each probiotic bacteria and (ii) evaluation of populations of probiotic bacteria in fermented milks formulated with citrus fibers. Citrus fibers enhanced L. acidophilus CECT 903, and L. casei CECT 475 survival in MRS during refrigerated storage, whereas erratic results were obtained for B. bifidum CECT 870, OF enhanced its growth and LF had inhibitory effect. Populations of probiotic bacteria decreased with storage time in MRS broth. The presence of yogurt starter bacteria in probiotic fermented milks favored the growth and survival of L. acidophilus and B. bifidum. Citrus fiber presence in fermented milks also enhanced bacterial growth and survival of the tested probiotic bacteria. This study indicates that citrus fiber enriched fermented milk have good acceptability and are good vehicles for a variety of commercial probiotics but survival of B. bifidum will need to be improved.     

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.