Short-chain Inulin Research Articles

Modulation of lipid metabolism and colonic microbial diversity of high-fat-diet C57BL/6 mice by inulin with different chain lengths.

The physicochemical properties, biological functions and microbial degradation of inulins differ according to their degree of polymerization. However, the relationship between inulin activities and its effect on gut microbiota remains unknown. In this study, high fat diet with inulin (1 or 5 g/kg·bw), either with short or long chains groups were administered to different groups of mice (n = 10) for 10 weeks in order to investigate the effect of inulin on the microbial diversity of the animals. Litchi pericarp procyanidins (LPPC) were used for comparison purposes. Furthermore, the lipid metabolism and key regulator genes in mice were determined. The results indicated that natural inulin (1 g/kg·bw) ingestion reduced the body weight of fat mice between week 6-9. Glutathione peroxidase (GSH-Px) activity in liver was remarkably higher after adding long chain inulin (5 g/kg·bw) compared to high-fat-diet mice. Moreover, high dose of natural inulin regulated malondialdehyde and advanced glycation end-products levels in mice liver. Likewise, the high dose of short-chain inulin increased sterol response element binding protein 1 (SREBP-1), β-Hydroxy β-methylglutaryl-CoA (HMG-CoA) and ATP-binding cassette transporter A1 (ABCA1) genetic expression. A significant change on the abundance of six genera in gut microbial profile suggested that inulin has the ability to modulate the lipid metabolism regardless of chain length, mainly due to its impact on colon microbiota variety.

Pasting, thermal, and rheological properties of rice starch partially replaced by inulin with different degrees of polymerization

Abstract: Blending with non-starch hydrocolloids is a crucial method to modify the processing properties of native starch. However, few comprehensive studies investigated the effects of inulin on the properties of rice starch (RS). In this research, we used three types of inulin with different degrees of polymerization (DP), namely, short-chain inulin (SI, DP 10), and long-chain inulin (LI, DP > 23), to investigate the effects of inulin on the pasting, thermal, and rheological properties of RS and to provide the foundation for the application of inulin in RS-based food. Inulin addition increased the pasting temperature of RS and decreased all viscosity indices, including the peak, final, breakdown, and Setback viscosities of RS. Compared with LI, SI and MI exerted stronger influence on the viscosity indices of RS. The gelatinization temperature levels of the RS–inulin blends were higher than that of starch alone. The RS and RS–inulin blends exhibited a shear-thinning property, and stress–shear hysteresis loops were observed during shear. Thixotropy followed the order RS > RS-LI > RS-MI > RS-SI. Dynamic viscoelasticity results indicated that the RS and RS–inulin blends displayed weak gel-like behavior. Replacement of RS with LI and MI evidently increased the elastic properties more than the viscous properties of the RS–inulin blends.

Separation and Probiotic Effect of Fructose with Different Polymerization Degrees in Inulin

Inulin is a natural fructose polymer that can be used as a fat substitute in foods such as dairy products and bakery products and is often added to food products due to its effect on the regulation of intestinal flora (also known as the prebiotic effect). However, there are few studies exploring whether there are functional differences between fructose species with different degrees of polymerization (DP). Therefore, we focused on the separation of fructose species with different DP and their different effects on the balance of intestinal flora. First, the fractional precipitation method was used to separate short-chain inulin (DP:2-9), medium-chain inulin (DP:10-23), and long-chain inulin (DP:23 and above). Then, male C57BL/6 mice were randomly distributed into four groups and fed with a high-fat diet(HFD), a high-fat diet with added short-chain inulin(SCI), a high-fat diet with added medium-chain inulin(MCI), or a high-fat diet with added long-chain inulin(LCI) for two weeks. Finally, RT-PCR was used to detect the relative abundance of specific bacteria after this feeding course. The results showed that the abundance of common probiotics increased, and some harmful bacteria reduced after SCI, MCI, and HCI treatment. As the short-chain inulin has the strongest effect on improving the balance of intestinal flora, it may be a promising treatment option for patients with obesity, fatty liver, diabetes or other gastrointestinal issues.

Physicochemical and rheological properties of cross-linked inulin with different degree of polymerization

Long-chain inulin (L-In) and short-chain inulin (S-In) from native inulin was separated through the method of alcohol precipitation. Cross-linked inulin with two different degree of polymerization (average DP = 6.88 and 15.10) were prepared in aqueous solutions by using the L-In and S-In respectively as raw material and sodium hexametaphosphate as cross-linker. Structural characteristics of cross-linked inulin were determined by Fourier-transform infrared spectroscopy and scanning electron microscopy. Compared with native L-In and S-In, cross-linked inulin had a higher intrinsic viscosity, stronger stability and moisture absorption capability, but lower water solubility. Only 1% reducing sugar produced when cross-linked inulin was heated within 100 °C, and inulin hydrolysis occurred in acidic environment (pH < 6). Rheological properties of inulin dispersions with different degree of polymerization were investigated and compared. The viscoelastic properties of steady shear measurements indicated that cross-linked inulin dispersions presented shear-thinning behaviors, which could be described by a power law model with determination coefficients (R2 = 0.9312–0.9926). The viscoelastic properties of dynamic frequency sweep measurements indicated that cross-linked inulin dispersion showed more solid viscoelastic properties than corresponding native inulin dispersions.

Effect of short chain inulin on the rheological and sensory characteristics of reduced fat set coconut milk yoghurt.

The effect of short-chain inulin on the rheological and sensory properties of reduced fat set coconut milk yoghurt was studied with whole fat coconut milk yoghurt as reference. The concentration of short-chain inulin was varied at 0, 5, 10, 15, and 20% w/v respectively. All the yoghurt samples displayed higher elastic modulus G' than viscous modulus G". However, 15% inulin yoghurt had the highest value for G' & G". The 15 and 20% inulin yoghurts displayed high yield stress (1036.7 ± 2.39 & 368.23 ± 0.30 Pa). Addition threshold of 15% was established, beyond this level there was a significant decrease in the yield stress, firmness, cohesiveness and consistency values of the reduced fat yoghurts. Using Pearson correlation analysis, no correlation was observed between firmness and yield stress, Similarly, there was significant correlation between the yield stress and instrumental viscosity r = 0.957; p < 0.01. Furthermore, all yoghurt samples displayed strain thinning behavior except whole fat yoghurt. Carbohydrate was affected by inulin incorporation. Addition of short chain inulin improved sensorial characteristics such as taste, and flavor, but did not display significant difference in color and odor of yoghurt samples. This article is protected by copyright. All rights reserved.

Development of Probiotic Fruit Juices Using Lactobacillus rhamnosus GR-1 Fortified with Short Chain and Long Chain Inulin Fiber

Typically, probiotics are consumed in dairy based products such as yogurt. However, given the rise in various diet types, non-dairy alternatives have been developed, such as inoculating fruit juices with probiotics. Lactobacillus rhamnosus GR-1 is a probiotic strain exerting a number of human health benefits such as the prevention of urinary tract infections. Therefore, the objective of this study was to determine the viability of L. rhamnosus GR-1 in apple cider, orange, and grape juice when fortified with either 4% short chain or 4% long chain inulin fiber over 72 h of fermentation and 30 days of refrigerated storage. The secondary objective was to determine consumer acceptability of apple cider and orange juice samples using the hedonic scale. All of the fruit juice samples achieved a mean viable count of at least 107 CFU/mL during 72 h of fermentation and 30 days of refrigerated storage. According to the sensory evaluation, which evaluated samples according to appearance, flavor, texture, and overall acceptability, apple cider juice with long chain inulin fiber proved to have the highest score for all characteristics except appearance. Therefore, this study indicated a potential for probiotic fruit juices as a valid alternative to dairy based probiotic products.

Chain length distribution of inulin from dahlia tubers as influenced by the extraction method

ABSTRACTA variety of fructans occurs in plants, having various configuration and chain lengths from 3 up to a few hundred fructose units. The structurally simplest fructan is a linear inulin, where the fructose units are linked by β-2,1 bonds, present mostly in Asteraceae and Cichorioideae (e.g. dahlia). The pharmacological effects of fructans depend mainly on the degree of polymerization (DP). Hence, a controlled DP distribution profile is essential for the expected spectrum of pharmacological activities. The aim of this study was to purify fructans from dahlia (Dahlia x hortensis Guill. cv.‘Ken’s Flame’) tubers with different inulin chain lengths profile. We developed the selective preparative approach, followed by qualitative and quantitative analyses by pulsed amperometry-high performance anion-exchange chromatography. The fructans were obtained by the extraction of dahlia tubers with water, concentrated under vacuum, subsequent precipitation of carbohydrate fraction by ethanol, followed by purification using four different combinations of absorbents such as Dowex® ion-exchange resin, aluminium oxide, calcium carbonate, and activated carbon. The highest content of short-chain inulin (38%) was in the crude fraction and after the separation on Al2O3 and CaCO3. All methods selectively enriched inulin in the middle-length chains. The highest concentration of high-quality long-chain inulin (16%) was obtained by consecutive washing through CaCO3, Al2O3, Dowex, and charcoal. This complex was also the most balanced in terms of the proportion among short-, medium-, and long-chain inulin (33%, 43%, and 16%, respectively).

Lactobacillus rhamnosus GR-1 in Fermented Rice Pudding Supplemented with Short Chain Inulin, Long Chain Inulin, and Oat as a Novel Functional Food

Lactobacillus rhamnosus GR-1 is a probiotic that has been shown to reduce the risk of urogenital problems and urinary tract infections. Rice pudding is a popular gluten-free dairy product, and could be a vehicle to deliver L. rhamnosus GR-1 to a broader population. The purpose of this study was to investigate the growth and viability of L. rhamnosus GR-1 in six fermented rice pudding samples, each one supplemented with one type of prebiotic (short-chain inulin-2% w/w, 4% w/w; long-chain inulin-2% w/w, 4% w/w) and oat-0.5% w/w, 1% w/w, along with control, over a 21-day storage period. The objective was to determine if the supplementation would have a positive effect on the microbial viability of L. rhamnosus GR-1, and to evaluate the sensory properties of the samples. All of the samples had viable levels of L. rhamnosus GR-1. Bacterial counts were at least 1 × 108 CFU/mL over the 21-day storage period. The probiotic rice pudding sample supplemented with 4% w/w short-chain inulin had the highest hedonic score for flavour, sweetness, texture, and overall acceptability. This study shows that the addition of short-chain inulin, long-chain inulin, and oat had no adverse supplementation effects on the viability of L. Rhamnosus GR-1. There is the potential for the production of a novel functional food.

Stabilisation mechanism of various inulins and hydrocolloids: Milk–sour cherry juice mixture

Milk–fruit juice mixtures, such as the mainly acidic nutraceutical soft drinks, usually suffer from phase separation due to aggregation of caseins at low pH. In this study, short‐chain inulin (SCI), native inulin (NI), long‐chain inulin (LCI) and a combination of long‐ and short‐chain inulins (LCI:SCI) (MIX) in different ratios (20:80, 50:50 and 80:20) were added (up to 10% w/v) to a milk–sour cherry juice mixture and their stabilisation mechanisms investigated using rheological, microstructural and zeta potential observations. In addition, gum tragacanth (GT) and Persian gum (PG) as adsorbing and guar gum (GG) as nonadsorbing hydrocolloids were combined with inulin to enhance their stabilising properties. Finally, sensory analyses were carried out on the stabilised samples. According to our findings, LCI fully stabilised the mixture (8% w/v), while LCI: SCI and NI only reduced phase separation at very high concentrations, and SCI had no significant effect on the stabilisation. Moreover, no inulin aggregates and rheological changes were observed with SCI. However, LCI, LCI: SCI and NI formed inulin aggregates and the mixtures became even more viscous and thixotropic (LCI &gt; LCI: SCL &gt; NI). Based on these observations, it can be concluded that chain length and concentration are two important factors that affect the functionality of inulin. On the other hand, the combination of inulin with GT and PG did not have any pertinent effect on the stabilisation. However, the mixture of inulin and GG could stabilise the mixtures at certain ratios and concentrations. Furthermore, in mixtures containing GG and SCI, GG played the main role in the stabilisation by increasing the viscosity and forming gel network.

The cell wall anchored β-fructosidases of Lactobacillus paracasei : Overproduction, purification, and gene expression control

Abstract Cell wall bound β-fructosidases (exo-inulinases, EC 3.2.1.80) of the probiotic bacterium Lactobacillus paracasei are the key enzymes involved in fructo-oligosaccharide (FOS) prebiotic fiber utilization. They consist of conservative catalytic region and large variable part with different number of Big3 domains for peptidoglycan binding. In this study, the first overproduction and purification of two different enzymes of this class (InuB41 and InuLC1) was reported. The biochemical features analysis showed similar pH, temperature optima and stabilities of both enzymes, not influenced by the cell-wall anchoring part. Substrate specificity revealed that InuB41 has the highest affinity to short-chain inulin, while InuLC1 possess highest affinity to levan. Despite the predicted difference of 80 amino acids, the molecular weight of both purified exo -inulinases is equal (∼100 kDa), probably due to enzyme truncation at the “hot loop” structure formed after the second Big3 domain. New data revealing the putative mechanism of catabolite repression on fos operon were obtained by engagement of the unique capability of the studied L. paracasei strains to utilize starch-inulin mixed polysaccharide sources. The performed combined gene transcription assay proved that starch and inulin are utilized simultaneously, since the genes encoding amylopullulanase and β-fructosidase fall under common expression control.

Influence of prebiotic and coating materials on morphology and survival of a probiotic strain of Lactobacillus casei exposed to simulated gastrointestinal conditions

Inulin type fructans are among the most studied prebiotics that contribute to enhance gastrointestinal system conditions. To improve the survival and stability of probiotic Lactobacillus casei, native inulin, long-chain and short-chain inulin, were separately incorporated into alginate and chitosan coated alginate beads during the microencapsulation of bacteria. Morphology, particle size and viability of different beads were measured before and after exposure to simulated gastro-intestinal condition. Application of inulin, with different chain lengths, did not alter the shape and size of alginate/inulin beads (2.25–2.28 mm) but slightly increased the size of chitosan-coated beads (about 2.9 mm), while the diameter of micro particles containing alginate alone was 2.2 mm. When alginate beads were exposed to the simulated gastric solution, their size was significantly decreased (by about 0.2 mm), while the size of chitosan-coated beads was not affected. Using inulin and chitosan-coating, the survival of co-encapsulated cells in simulated gastro-intestinal condition was improved with only 2.7–2.9 logs reduction for L. casei and long-chain inulin showed the highest survival rate (2.7 log reduction).

Hydrolysed inulin alleviates the azoxymethane-induced preneoplastic aberrant crypt foci by altering selected intestinal microbiota in Sprague–Dawley rats

Context Inulin, a non-digestible carbohydrate isolated from Helianthus tuberosus L. (Asteraceae), has been shown to alter the gut beneficial bacteria including Lactobacillus spp. and Bifidobacteria. Inulin also influences the activities of intestinal microbiota that could prevent the colon cancer development.Objective This study determines the effect of hydrolysed inulin with different degrees of polymerisation on alteration of intestinal microbiota and their activities on azoxymethane (AOM)-induced preneoplastic aberrant crypt foci (ACF) in rats.Materials and methods Seventy-two male Sprague–Dawley rats were randomly divided into six groups (three control and three AOM-treated groups) and the animal were fed with either a normal diet or diet containing 10% of long-chain inulin (InuL) or short-chain inulin (InuS), respectively, for 17 weeks. Colon cancer was induced in rats by injecting AOM subcutaneously at the 8th and 9th week of the study period. At the end of the experiment, cecal contents of rats were examined for selected microbiota, organic acids, putrefactive compounds and microbial enzymes. ACF formation was microscopically examined.Results The inulin diets significantly increased the weight and decreased the pH of the caecal content. The rats fed with InuL-supplemented diet showed approximately 2.9- and 6.8-fold increases in the biomass of Lactobacillus spp. and Bifidobacteria, respectively. Naive and AOM-treated rats fed with inulin-supplemented diet showed ∼1.3- and ∼2.2-fold decreases in the biomass of Escherichia coli and Salmonella enterica serovar Typhi, respectively. Inulins significantly decreased the colonic concentration of phenol, p-cresol and indole. Reduction in the activity of microbial enzymes such as β-glucuronidase, azoreductase and nitroreductase were observed in inulin-treated animals. Reduction in the ACF formation has been observed in inulin-treated groups.Discussion and conclusion The present study demonstrates that dietary administration of inulin reduces the formation of preneoplastic lesions in the colon, possibly by altering the microecology and microbial activities on carcinogenesis.

Structural and metabolic changes in rhizophores of the Cerrado species Chrysolaena obovata (Less.) Dematt. as influenced by drought and re-watering.

The high fructan contents in underground organs of Cerrado species, high water solubility, and fast metabolism of these compounds highlight their role as carbon storage and as an adaptive feature in plants under drought. In this study, we showed that anatomical structure, in association with soluble compounds and metabolism of inulin-type fructans were modified in rhizophores of Crysolaena obovata submitted to water suppression and recovery after re-watering. Plants were subjected to daily watering (control), suppression of watering for 22 days (water suppression) and suppression of watering followed by re-watering after 10 days (re-watered). Plants were collected at time 0 and after 3, 7, 10, 12, 17, and 22 days of treatment. In addition to changes in fructan metabolism, high proline content was detected in drought stressed plants, contributing to osmoregulation and recovery after water status reestablishment. Under water suppression, total inulin was reduced from approx. 60 to 40%, mainly due to exohydrolase activity. Concurrently, the activity of fructosyltransferases promoted the production of short chain inulin, which could contribute to the increase in osmotic potential. After re-watering, most parameters analyzed were similar to those of control plants, indicating the resumption of regular metabolism, after water absorption. Inulin sphero-crystals accumulated in parenchymatic cells of the cortex, vascular tissues and pith were reduced under drought and accompanied anatomical changes, starting from day 10. At 22 days of drought, the cortical and vascular tissues were collapsed, and inulin sphero-crystals and inulin content were reduced. The localization of inulin sphero-crystals in vascular tissues of C. obovata, as well as the decrease of total inulin and the increase in oligo:polysaccharide ratio in water stressed plants is consistent with the role of fructans in protecting plants against drought.

How combinations of dietary fibres can affect physicochemical characteristics of pasta

The production of high quality functional pasta from non-conventional raw materials represents a challenge. A partial substitution (15 g/100 g) of durum wheat semolina with long-chain inulin (HPX) and short-chain inulin (GR), Glucagel, psyllium and oat material (added individually and in combinations) was performed in order to increase the level of dietary fibre intake. The cooking, textural and colour characteristics of the pastas were evaluated and compared to control sample containing exclusively durum wheat semolina. Generally, material addition to the durum wheat pasta increased cooking losses, swelling index and water absorption, whilst reduced firmness and resistance to uniaxial extension of pastas. Raw spaghetti samples resulted significantly darker (L*) and more redness (a*) than control pasta. In the cooked pasta, all inulin enriched samples were brighter than semolina pasta. Pasta prepared with 15 g/100 g semolina of oat flour showed the best performance (except for the colour) compared to the other experimental pasta samples, but was significantly different to control durum wheat sample. Combinations of fibre rich additions were studied with the inclusion of inulin GR having a less deteriorating effect when added in combination with oat flour. This illustrates that some fibre rich sources may act better in combinations than separately.

Effects of Short-Chain and Long-Chain Inulin on the Quality of Probiotic Yogurt Containing L actobacillus rhamnosus

This study investigated the effects of adding short-chain and long-chain inulins on the growth of Lactobacillus rhamnosus and the physicochemical and sensory properties (appearance, structure-texture, odor and taste) of probiotic yogurt during cold storage. The inulin-supplemented yogurt batches were compared with control batches of unsupplemented yogurt and L. rhamnosus-inoculated yogurt. The inulins were incorporated at 2% w/w in the yogurt mixtures that were inoculated with L. rhamnosus and mixed cultures of Streptococcus thermophilus and L. delbrueckii ssp. bulgaricus. The contents of organic acids (lactic, citric, acetic, propionic, formic and butyric) profile were determined using high-performance liquid chromatography. The results indicated that the viability of L. rhamnosus (6.71 log10 cfu/g) in probiotic yogurt was enhanced by the presence of short-chain inulin (RSI). Consequently, yogurt with short-chain inulin (RSI) received higher scores for odor, taste and overall acceptance than did yogurt containing long-chain inulin (RLI). However, the chain lengths of the inulins did not significantly affect the consistency, product appearance or the organic acid profile. Practical Applications Inulin is a natural component of some fruits and vegetables and widely used in functional foods for its nutritional benefits. In addition to its health promoting properties, as a dietetic fibre and as a prebiotic ingredient inulin has technological properties, as a low-calorie sweetener, fat substitute and texture modifier. Inulin also promotes healthy probiotic bacteria grown in the colon and enhances calcium absorption and immune functions. This study provided information on the effects of short-chain and long-chain inulin on the properties of probiotic yogurt containing Lactobacillus rhamnosus.

Impact of soluble dietary fibre on the characteristics of extruded snacks

The aim of this experimental work was to evaluate the effect of inulin addition on dough rheological properties, texture and sensory quality of extruded snacks. Two commercial fructan products of different degree of polymerisation (DPn) were used at levels from 2% to 7% (DPn = 10 for inulin GR; DPn = 23 for inulin HPX). Dough rheological properties were investigated using dynamic measurements in the linear viscoelastic range (frequency sweep and time cure tests) and farinograph test. Colour, specific volume (Vs), mechanical and sensory properties of snacks were evaluated. Fibre enrichment lowered dough consistency due to a reduction in water absorption. Large differences in elastic properties of samples were observed between 25 and 95 °C due to incompatibility between inulin and starch and different kinetics of starch gelatinization. The magnitude of G′ decreased with the increase in fibre content and GR had a greater effect than HPX. Inulin GR increased product expansion and hardness compared with the reference. No significant differences in Vs and mechanical properties were observed between reference and inulin HPX enriched samples up to 5%, while lower values were observed at 7%. Short-chain inulin lowered the extent of non-enzymatic browning. Snacks made with 5% inulin HPX can be used to enhance the fibre content without impacting negatively on product quality.

Chain length of inulin affects its degradation and the microbiota in the gastrointestinal tract of weaned piglets after a short-term dietary application

Dietary inulin can affect the composition and metabolic activity of the gastrointestinal microbiota in piglets. To investigate whether the chain length of inulin may influence its stability in the gut and the bacterial community, 18 weaned piglets were housed 2 per cage, with 1 female and 1 castrated male animal each. The piglets received a control diet without or with 4% inulin, defined by an average degree of polymerisation (DP) of 31 (short-chain, I31) or 57 (long-chain, I57), with 6 piglets/diet. After a short feeding period of 6d, fructan concentrations, selected bacterial groups, lactic acid, short-chain fatty acid concentrations, and the pH were determined in the digesta of different segments of the gastrointestinal tract. The results indicated that differences in the microbial degradation of inulin were depending on the DP. Compared to the short-chain inulin, the concentrations of the long-chain inulin were numerically greater in the small intestine and caecum, and greater in the digesta of the ascending colon. Differences were also observed in the bacterial composition of the digesta, showing greater cell numbers of enterococci (P=0.029), bifidobacteria (P=0.029), and Lactobacillus mucosae (P=0.028) in the ileum in group I57 compared to group I31. However, most bacteria tended to be numerically reduced in the ileum in group I31 compared to both control and I57 groups. Minor effects were observed in the ascending colon: L. reuteri and L. amylovorus were decreased in group I57 compared to the control group (P=0.031 and 0.034, respectively), and L. mucosae was decreased in group I31 compared to the control animals (P=0.029). The concentrations of bacterial metabolites were distinctively changed in the large intestine of the piglets fed inulin. The pH was lower in the rectum contents in group I57 compared to the control piglets (P=0.026), but lactic acid and total short-chain fatty acid concentrations were not affected. The molar ratios of propionic acid increased in the caecal contents (P=0.040) and in both, the ascending and descending colonic digesta (P=0.017 and 0.013, respectively) in group I57 compared to the control group, while acetic acid decreased (P<0.001) and n-valeric acid increased (P<0.001 and P=0.011, respectively) in the digesta of the ascending and descending colon in group I57. In conclusion, the microbial degradation of inulin was dependent on its chain length. Long-chain inulin affected the microbial fermentation more pronounced compared to short-chain inulin. The effects were already observed after 6d, a relatively short application period, indicating that inulin may be used specifically during the sensitive post-weaning period for piglets.

Analysis of the hydrolysis of inulin using real time 1H NMR spectroscopy

The hydrolysis of various carbohydrates was investigated under acidic conditions in real time by 1H NMR spectroscopy, with a focus on the polysaccharide inulin. Sucrose was used as a model compound to illustrate the applicability of this technique. The hydrolysis of sucrose was shown to follow pseudo first order kinetics and have an activation energy of 107.0kJmol−1 (SD 1.7kJmol−1). Inulin, pullulan and glycogen also all followed pseudo first order kinetics, but had an initiation phase at least partially generated by the protonation of the glycosidic bonds. It was also demonstrated that polysaccharide chain length has an effect on the hydrolysis of inulin. For short chain inulin (DPn 18, SD 0.70) the activation energy calculated for the hydrolytic cleavage of glucose was similar to sucrose at 108.5kJmol−1 (SD 0.60). For long chain inulin (DPn 30, SD 1.3) the activation energy for the hydrolytic cleavage of glucose was reduced to 80.5kJmol−1 (SD 2.3kJmol−1). This anomaly has been attributed to varied conformations for the two different lengths of inulin chain in solution.

Influence of the chain-length distribution of inulin on the rheology and microstructure of prebiotic dairy desserts

The changes in rheological properties and microstructure of inulin-enriched custard desserts were studied for a seven-day period of refrigerated storage. Desserts prepared with 7.5% short-chain inulin (CLR), long-chain inulin (TEX), native inulin (IQ), and a mixture of short and long-chain inulin (MIX) were compared. Rheological changes and inulin aggregates formation were not observed in CLR samples during the seven-day storage period. However TEX, MIX and IQ samples formed inulin aggregates and consequently became more thixotropic, consistent and elastic. These rheological changes, the rate of the inulin aggregates formation and the percentage of volume occupied by them varied among samples in the following order TEX > MIX > IQ. Although the same trend was observed for both skimmed-milk and whole-milk samples the effects of inulin type and storage time on rheology and microstructure were less pronounced in the whole-milk samples.

Supplemental Dietary Inulin of Variable Chain Lengths Alters Intestinal Bacterial Populations in Young Pigs1–3

Previously, we showed that supplementation of diets with short-chain inulin (P95), long-chain inulin (HP), and a 50:50 mixture of both (Synergy 1) improved body iron status and altered expression of the genes involved in iron homeostasis and inflammation in young pigs. However, the effects of these 3 types of inulin on intestinal bacteria remain unknown. Applying terminal restriction fragment length polymorphism analysis, we determined the abundances of luminal and adherent bacterial populations from 6 segments of the small and large intestines of pigs (n = 4 for each group) fed an iron-deficient basal diet (BD) or the BD supplemented with 4% of P95, Synergy 1, or HP for 5 wk. Compared with BD, all 3 types of inulin enhanced (P < 0.05) the abundance of beneficial bifidobacteria and lactobacilli in the microbiota adherent to intestinal mucus of various gut segments of pigs. These changes were seen as proximal as in the jejunum with P95 but did not appear until the distal ileum or cecum with HP. Similar effects of inulin on bacterial populations in the lumen contents were found. Meanwhile, all 3 types of inulin suppressed the less desirable bacteria Clostridium spp. and members of the Enterobacteriaceae in the lumen and mucosa of various gut segments. Our findings suggest that the ability of dietary inulin to alter intestinal bacterial populations may partially account for its iron bioavailability-promoting effect and possibly other health benefits.