Lactulose production from lactose by recombinant cellobiose 2‐epimerase in permeabilised Escherichia coli cells

Caldicellulosiruptor saccharolyticus cellobiose 2‐epimerase (CsCE) catalyses the single substrate lactose into lactulose and is the most efficient enzyme ever found for the enzymatic synthesis of lactulose. Ethanol‐permeabilised Escherichia coli cells containing CsCE were used as biocatalysts for lactulose production. The reaction conditions for maximum lactulose production were optimised to be 600 g L^?1 lactose, pH 7.5, 80 °C and 12.5 U mL^?1 of whole‐cell biocatalyst. After incubated at Na₂HPO₄–NaH₂PO₄ buffer for 2 h, approximately 390.59 g L^?1 lactulose was obtained with a conversion yield of 65.1%. The lowest production and conversion yield of epilactose were also found in Na₂HPO₄–NaH₂PO₄ buffer with a final concentration of 11.7 g L^?1 and a conversion yield <2%. The results represent a promising technology to attain high production and conversion yield of lactulose with a high purity on industrial scale.     

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.     

Inulin and probiotic concentration effects on fatty and linoleic conjugated acids in cream cheeses

The aim of this study was to evaluate the changes in the lipid profile, especially in conjugated linoleic acid (CLA), in 12 cream cheese batches with different prebiotic (inulin) and probiotic (Bifidobacterium animalis and Lactobacillus acidophilus) concentrations stored for 45 days at 8 ± 0.5 °C and analyzed every 15 days. A Central Rotational Composite Design was used to establish the prebiotic and probiotic concentrations. The effect of the pre- and probiotic concentrations on CLA contents (mg g⁻¹ of fat) was verified by plotting the response surface. The linear, quadratic, and interaction coefficients of the multiple linear regression for both prebiotic and probiotics were not significant (p > 0.05). No significant changes were observed neither in the lipid profile nor in the CLA content among the different batches, in which fatty acid composition and CLA concentrations were similar to the milk used in the preparation of the cream cheese and also to the control batch.     

Isomaltooligosaccharide synthesised from rice starch and its prebiotic properties in vitro

The isomaltooligosaccharides (IMOs) were produced from rice starch with a maximum conversion yield of 84% and had a concentration of 372.5 mg mL^?1. Compositions of IMO consisted of 26.7% isomaltohexaose (DP6), 16.2% isomaltotetraose (DP4), 19.6% d ‐panose (DP3), 21.4% and isomaltose (DP2) and had a dietary fibre content of 1.1%. In vitro (consisted of three vessels) fermentation of instant Sang‐Yod rice porridge (ISYRP) mixed with IMO showed a slight increase in beneficial bacteria, bifidobacteria and lactobacilli. On the other hand, the pathogenic bacteria, clostridia and bacteroides were decreased (P < 0.05). The highest prebiotic index (PI) was found in Vessel 1 (0.13). Butyric acid was found at the highest concentration on day 11 (75.1 mm ), and it was decreased at day 21 (63.4 mm ) in Vessel 1. In conclusion, the ISYRP mixture of IMO was showed a good preference in prebiotic properties.     

Short chain xylooligosaccharides: a potential prebiotic used to improve batter fermentation and its effect on the quality attributes of idli,a cereal–legume‐based Indian traditional food

Xylooligosaccharides (XOS), a potential prebiotic exhibits important technological characteristics and interesting nutritional properties. The major fraction in XOS produced enzymatically from corncob was characterised as β‐d ‐xylopyranosyl‐(1,4)‐d ‐xylanopyranose (xylobiose) using ¹³C and 2D‐HSQC NMR. The use of this XOS as a prebiotic in idli, a cereal/legume‐based fermented cake, and its effect on texture, fermentation and sensory characteristics was investigated. Idli batter was fermented with different concentrations of XOS (0, 0.2, 0.4 and 0.6% w/v) for 4–18 h conventionally. The addition of XOS markedly increased lactic acid bacteria number (9.88 ± 0.08 log cfu g^?1) which resulted in rapid reduction in pH (4.61 ± 0.03) and specific gravity after 6 h of fermentation when compared to conventional batter fermentation for 18 h without XOS (9.46 ± 0.06 log cfu g^?1). Instrumental (colour and texture) and sensory evaluation indicated that the optimum conditions were 0.4% XOS and 6 h fermentation. Idlis with XOS had higher moisture content and a softer texture. Addition of XOS benefits both fermentation and idli quality.     

Antimicrobial and antidiabetic potential of synbiotic fermented milk: A functional dairy product

The current study was based on evaluation of the therapeutic potential (antimicrobial and antidiabetic) of a synbiotic fermented milk product developed by optimising levels of the prebiotic ingredients (fructooligosaccharide and isomaltooligosaccharide). The maximum growth rate (0.27 ± 0.21a cfu/mL) of Lactobacillus acidophilus ATCC^® 4357? was observed with 2.345–2.445% of fructooligosaccharide and 2.53–2.62% of isomaltooligosaccharide. Significant antimicrobial potential of the synbiotic fermented milk was observed against Escherichia coli and Staphylococcus aureus due to the addition of prebiotics. Similarly, the final product also showed 62.9%, 71.5% and 57.0% reduction in blood glucose, urea and creatinine levels, respectively, of diabetic rabbits, when supplemented with 6% of the synbiotic fermented milk. A synbiotic fermented milk product with significant therapeutic potential could be developed using fructooligosaccharide and isomaltooligosaccharide as prebiotic ingredients.     

Production,iron analysis and consumer perception of functional Thai Sinlek iron rice (Oryza sativa) drink

We produced the iron rice (IR) drink, determined the relevant chemical composition and antioxidant activity and tested the consumers’ degree of satisfaction. IR grains were digested with α-amylase and analysed chemical composition and antioxidant activity, while the hydrolysate (pH 4.0) and flavouring agents were added for final preparation of the IR drink. The IR hydrolysate contained a total iron content of 13.9 mg g⁻¹, a total phenolic content of 1.33 ± 0.07 mg gallic acid equivalent g⁻¹ and γ-oryzanol of 70.12 ± 2.7 mg kg⁻¹ rice grain, all of which inhibited the generation of free radicals in a concentration-dependent manner. The IR drink was composed of flavonoids and phenolic acids for which kaempferol was predominant. The members of all three groups of elderly subjects who consumed the low-dose IR (1.47 mg iron/100 mL), high-dose IR (2.74 mg iron/100 mL) and white rice (WR; 0.5 mg iron/100 mL) drinks expressed satisfaction and interest with the beverages at 91.2%, 100% and 88.9%, respectively. In terms of sensory evaluation, the low-dose IR drink revealed a higher acceptance rating than high-dose IR and WR (P < 0.05). Notably, the Sinlek rice drink was abundant with iron, anti-oxidative phenolics and γ-oryzanol, for which consumers expressed an overall degree of acceptance (8.1 ± 1.1).     

Innovative production of multistrain synbiotic product using Thai-pigmented rice and rice bran oil

This study found that the isolated probiotics Lactobacillus paracasei KUKPS6201, L. acidophilus KUKPS6107, L. reuteri KUKPS6103, L. rhamnosus KUKPS6007, L. salivarius KUKPS6202, Bacillus coagulans KPSTF02 and Saccharomyces boulardii KUKPS6005 had high potential for probiotic properties. All strains had antibacterial activity and high antioxidant activity of 1.654 ± 0.017 mg Trolox mL⁻¹ probiotic extract. The selected strains could survive in a simulated gastrointestinal tract under anaerobic conditions and showed no haemolytic activity. Furthermore, the probiotic strains were strongly auto-aggregated and also showed co-aggregated ability with pathogenic bacteria. The probiotic microorganisms demonstrated high ability to adhere to Thai-pigmented rice grains. The results of analysis of these probiotics showed that Riceberry rice bran oil was an excellent prebiotic. A synbiotic product containing Thai-pigmented rice grains (cultivar Riceberry, Luem Pua and Black Jasmine) and rice bran oil was produced. After 8 weeks of storage, the viability of the probiotics in terms of multistrains was 7.36 ± 0.04 log CFU g^–1 (85.78% survival rate). Microbiological safety testing indicated that the amounts of contaminants were acceptable. This study provided the first scientific report on the feasibility of applying Thai-pigment rice, rice bran oil and mixed-culture probiotics as a novel functional synbiotic product.     

Cranberry seed fibre: a promising prebiotic fibre and its fermentation by the probiotic Bacillus coagulans MTCC 5856

Cranberry, a versatile fruit, is known for nutritional as well as medicinal properties due to the presence of bioactive compounds. However, cranberry fruit has not been fully explored for its prebiotic potential. Therefore, this study was conducted to evaluate prebiotic potential of cranberry seed fibre (CSF) and also evaluate its fermentability by the probiotic strain Bacillus coagulans MTCC 5856. The resistance to gastric acid and porcine pancreatic enzymatic (PPE) hydrolysis of CSF was investigated using an in vitro model. It was found that CSF was resistant to gastric acid and also nondigestible to PPE hydrolysis. CSF as sole nutrition source was evaluated for the fermentability by B. coagulans MTCC 5856. A significant amount of short‐chain fatty acids was produced by the B. coagulans MTCC 5856 while fermenting cranberry fibres anaerobically. CSF supported the growth of B. coagulans MTCC 5856 and also inhibited the growth of E. coli ATCC 25922 when cocultured in an anaerobic environment. CSF from the cranberry fruit exhibited prebiotic potential and also found to be fermentable by B. coagulans MTCC 5856. This study provided the scientific evidence of CSF as a prebiotic fibre and also its suitability with the probiotic B. coagulans MTCC 5856 for an ideal synbiotic preparation.     

Microencapsulation of Lactobacillus acidophilus ATCC 43121 with prebiotic substrates using a hybridisation system

The objective of this study was to evaluate the effects of prebiotic substrates on the growth of Lactobacillus acidophilus ATCC 43121 and to investigate the utilisation of these prebiotic substrates as coating materials for microencapsulation. The cell growth of L. acidophilus ATCC 43121 was significantly increased in the presence of fructooligosaccharide, lactulose and raffinose. The microencapsulation of L. acidophilus ATCC 43121 cells was carried out by dry surface reforming process (hybridisation) using the selected prebiotic substrates and the enteric coating material, Sureteric^TMsans. Scanning and transmission electron microscopy revealed that the double‐microencapsulated bacteria exhibited smooth, rounded external surfaces, with a thick external coating composed of the prebiotic substrates and the Sureteric. The acid (artificial gastric juice) or heat tolerance (55 °C) of the double‐microencapsulated preparations (prebiotic and enteric coating) was significantly higher than that of the uncoated and single‐coated (enteric coating) preparation at prolonged acid (5 h) or heat exposure (3 h). On the contrary, no significant differences were found in salt tolerance. During the storage up to 20 days at 25 and 37 °C, the stability of L. acidophilus ATCC 43121 was significantly improved by double‐microencapsulation.     

Extremophile microalgae as feedstock for high-value carotenoids: A review

There are places in our planet where environmental conditions are beyond normal limits for growth but still harbour life. Extremophile microalgae are the candidates for large-scale production because (i) their extreme growth conditions help to avoid unwanted contaminations, facilitating their production and (ii) in order to survive under harsh environments, these microorganisms synthesise valuable uncommon biomolecules. Extremophile microalgae include Arthrospira platensis, used as a source of phycocyanin and produced under highly alkaline conditions, and Dunaliella salina, which is industrially produced as a source of β-carotene and can naturally resist salinity conditions exceeding 300 g L⁻¹. Microalgae can be produced on non-arable lands, using seawater, and within a wide range of environmental conditions, allowing their production in almost any part of the planet. The current paper aimed at highlighting the biotechnological potential of extremophile microalgae as sources for carotenoids, valuable molecules used as pigments and health-promoters.     

Effect of inulin on growth and bacteriocin production by Lactobacillus plantarum in stationary and shaken cultures

The prebiotic effect of inulin added to MRS medium on growth and bacteriocin production by L. plantarum ST16 Pa was investigated in stationary cultures in anaerobic jars with medium containing 0.025% sodium thioglycolate or in flasks shaken at 100 rpm. In the presence of 1% inulin in anaerobic stationary cultures, this strain produced lactic acid at a level that was 36.5% higher than in the absence of the polysaccharide. In shaken cultures without inulin, cell count was 54% higher than in the stationary ones. Under stationary conditions in anaerobic jars, the addition of inulin increased the maximum specific growth rate from 0.37 to 0.49 h^?1 and reduced the generation time from 1.85 h to 1.40 h. Consequently, the exponential phase was shortened from 12 to 9 h when the cells were grown in stationary cultures with the oxygen scavenger. Despite this effect of inulin on growth rate, stationary cultures without inulin displayed higher antimicrobial activity against Listeria monocytogenes L104 (3200 AU/mL) than cultures with inulin (1600 AU/mL); therefore, inulin behaved as a compound able to accelerate growth rather than to stimulate bacteriocin production. The results presented in this study are very promising, as L. monocytogenes is a well‐known foodborne pathogenic microorganism. Moreover, L. plantarum ST16 Pa has proven to be a potential producer of a natural food preservative at an industrial level.     

Evaluation of furosine,lactulose and acid-soluble β-lactoglobulin as time temperature integrators for whipping cream samples at retail in Austria

Three heat load indicators, i.e., furosine, lactulose and acid-soluble β-lactoglobulin, were determined in whipping cream samples purchased from Austrian market (n = 33), as well as commercial samples obtained directly from one Austrian dairy company (one brand, n = 25). Furosine contents were 47.8 ± 14.0, 72.2 ± 36.6, and 172.5 ± 17.7 mg 100 g⁻¹ protein, and β-lactoglobulin contents were 143 ± 91, 195 ± 150, and 89 ± 31 mg L⁻¹ for retailed pasteurised, extended shelf life (ESL), and ultra-high temperature (UHT) cream samples, respectively. Lactulose concentrations (analysed enzymatically) were 29 ± 10, 56 ± 41, and 201 ± 24 mg L⁻¹ for pasteurised, ESL and UHT cream samples, respectively. Linear correlation obtained for furosine and lactulose concentrations indicated that these indicators can reliably assess the heat load of pasteurised, ESL and UHT cream samples, whereas β-lactoglobulin was definitely not appropriate to discriminate between these heating categories.     

Fermentative properties of starter culture during manufacture of kefir with new prebiotics derived from lactulose

The fermentation properties of a starter culture during kefir manufacture was studied with the inclusion of one emerging lactulose-derived oligosaccharide prebiotic and with the well-recognised galactooligosaccharide and lactulose prebiotics at different doses (2 and 4%). Microbial growth, glycerol, lactic and citric acids and short-chain fatty acids and carbohydrate utilisation during fermentation and cold storage of control and prebiotic supplemented kefirs were determined. Prebiotic levels remained unaltered during fermentation (24 h) and storage (28 days), with the exception of a decrease (7.3%) of lactulose in kefir with 4% prebiotic. Consequently, the viability of lactic acid bacteria and yeasts, as well as the pH or level of fermentation metabolites was similar for all kefirs. Therefore, our data highlight the suitability of kefir as a matrix for the consumption of a variety of prebiotics, including that of novel synthesis as lactulose-derived oligosaccharides, widening their potential food uses and applications.     

Effects of inulin,fructooligosaccharides/glucose and pH on the shape of the death kinetic of Lactobacillus reuteri DSM 20016

The viability of Lactobacillus reuteri, Lb. delbrueckii subsp. bulgaricus and Lb. paracasei was assessed in a laboratory medium containing inulin (5 g L^?1) or glucose + FOS (fructooligosaccharides) (2.5 + 2.5 g L^?1). Data were modelled through the Weibull equation pinpointing that prebiotics determined a decrease in the shape parameter. In the 2nd step, L. reuteri was used as the test microorganism; pH, storage temperature and the amounts of FOS + glucose and inulin were combined through a 4‐variable/5‐level central composite design. Temperature, pH and glucose + FOS affected the microbiological shelf life; inulin was not significant. The maximum value of shelf life was found at pH 8.5 and with 5.0 g L^?1 of glucose + FOS. The combination of pH and prebiotics affected the shape parameter with a shift from a convex to a concave trend and vice versa: their effect was different depending on the use of a single prebiotic or a mix.     

Lactose isomerization into lactulose in an electro-activation reactor and high-performance liquid chromatography (HPLC) monitoring of the process

Lactulose production is a complex process that is affected by several operational and experimental conditions. This study investigated the production of prebiotic lactulose using an electro-activation reactor. The experiments were performed at an ambient temperature (22 ± 1 °C), and the lactose starting concentration was constantly maintained at 5% (w/v). This work used HPLC to investigate the retention behaviors of the disaccharides (lactulose and lactose) and the by-products of lactulose production (glucose, galactose and fructose) under varying experimental conditions such as electric potential difference, central cell compartment electrolyte concentration and electro-activation time. The results were then correlated with the electric current density, the electrical global resistance of the system, the pH, the temperature and the Joule heating effect. The highest lactulose yield that was obtained during the isomerization of lactose was ≈30% at a voltage of U = 28 V, an electrolyte concentration C_Na2SO4 = 0.5 M, a temperature T = 26 °C, an alkaline medium pH = 10.79, and a running time τ = 20 min.     

In vitro evaluation of the fermentation of added‐value agroindustrial by‐products: cactus pear (Opuntia ficus‐indica L.) peel and pineapple (Ananas comosus) peel as functional ingredients

Agroindustrial by‐products derived from fruit processing are an important source of biocompounds that can be used as functional food ingredients. The objective of this work was to evaluate cactus pear and pineapple peel flours as an alternative carbon source during fermentation using bacteria with probiotic potential. The total fibre content of both flours was over 60%, with total soluble carbohydrate content around 20%, indicating a good carbon source for lactic acid bacteria. Kinetic parameters indicate that peel flours are a suitable carbon source because the lactic acid bacteria grow (mean growth rate constant, k, values close to glucose, 1.52 h) and acidify the culture media (maximum acidification rate, V_max, approximately 1.60 pH × 10^?3 min^?1). There was no difference in prebiotic potential or prebiotic activity score for both the peel flours. Pediococcus pentosaceus performs better during fermentation. In this respect, cactus pear and pineapple peel flours can be used as functional ingredients due to their fermentable properties.     

Raffinose family oligosaccharides in seed of Glycine max cv. Chiang Mai60 and potential source of prebiotic substances

Raffinose family oligosaccharides (RFOs) content in Glycine max seed of cultivar Chiang Mai60, a local soybean of Thailand, was investigated. RFOs and other low molecular weight sugars were extracted by 50% (v/v) ethanol and quantified by high‐performance liquid chromatography (HPLC). The prebiotic property of this extract was subsequently studied by in vitro method. The results showed that the concentrations of raffinose, stachyose and verbascose were 6.74 ± 1.62, 145.32 ± 18.74 and 1.60 ± 0.52 mg g^?1 dry seed, respectively, while glucose and sucrose were detected at 10.73 ± 1.35 and 13.28 ± 2.16 mg g^?1 dry seed, respectively. The growth of four Lactobacilli probiotics were increased significantly in a basal liquid medium supplemented with this ethanolic extract as carbon source compared to glucose supplementation. Subsequently, defined mixed culture was studied and it was found that growth stimulation of total Lactobacilli by extracted sugars resulted in the suppression of Escherichia coli and Salmonella enterica serovar Typhimurium growth. It could be concluded that this cultivar showed the RFOs‐rich content and a potential to be a source of an effective prebiotic substance for food application.     

Performance of different microbial cultures in potentially probiotic and prebiotic yoghurts from cow and goat milks

Lactobacillus acidophilus or Bifidobacterium animalis subsp. lactis Bb‐12 and green banana pulp were used in order to obtain potentially probiotic and prebiotic yoghurts, which were compared over a 45‐day storage period. Goat milk yoghurts demonstrated probiotic effects up to 45 days of storage. Cow milk yoghurts produced with B. animalis subsp. lactis Bb‐12 showed a probiotic effect reduction during the storage period (1.74 log CFU/g). The type of milk affected the yoghurts’ chemical and physicochemical properties. Sensory acceptance was also affected, where cow milk yoghurts were better accepted than goat milk ones.     

Calcium–inulin wheat bread: prebiotic effect and bone mineralisation in growing rats

The nutritional performance of wheat bread prepared with calcium carbonate and inulin was studied in growing rats fed with three diets (BD: diet containing bread with calcium and inulin, SD: diet with synergy1^® and CD: diet control‐AIN 93G‐) up to 60 days. Animals fed with BD consumed less diet and presented a caecal pH (5.5) lower than that of the CD group (7.0) with the highest amount of anaerobic micro‐organisms (1.68 × 10¹⁰ cfu g^?1) at 23 days. Microbiota profiles (DGGE) indicated that BD groups presented 66% of similarity and greater variability than the CD group, suggesting changes due to the prebiotic effect of inulin. In the BD group, calcium apparent absorption (AA_Ca: 83%), bone mineral content (18 g kg^?1), proximal tibia density (242 mg cm^?2) and bone volume (BV: 41%) were higher than in the CD group. The decrease in pH due to fermentation in the large intestine increased calcium bioavailability. Although all variables studied on animals fed with diets containing the prebiotic were improved with respect to a control without inulin, in the case of bread diet, many of them were similar to those of the positive control. Consequently, the prebiotic effect was not altered during the baking process. Results suggest that wheat bread, a highly consumed product throughout the world, is an adequate vehicle for including calcium and inulin in healthy food.