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Ultrasound has been applied in food processing for various purpose, showing potential to advance the physical and chemical modification of natural compounds. In order to explore the effect of ultrasonic pretreatment on the complexation of inulin and tea polyphenols (TPP), different frequencies (25, 40, 80 kHz) and output power (40, 80, 120 W) were carried out. According to the comparison in particle size distribution and phenolic content of different inulin-TPP complexes, it was indicated that high-intensity ultrasonic (HIU) treatment (25 kHz, 40 W, 10 min) could accelerate the interaction of polysaccharides and polyphenols. Moreover, a series of spectral analysis including UV-Vis, FT-IR and NMR jointly evidenced the formation of hydrogen bond between saccharides and phenols. However, the primary structure of inulin and the polysaccharide skeleton were not altered by the combination. Referring to field emission scanning electron microscopy (FESEM), the morphology of ultrasound treated-complex presented a slight agglomeration in the form of bent sheets, compared to non-treated sample. The inulin-TPP complex also revealed better stability based on thermogravimetric analysis (TGA). Thus, it can be speculated from the identifications that proper ultrasonic treatment is promising to promote the complexation of some food components during processing., (Copyright © 2021. Published by Elsevier B.V.)

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., (Copyright © 2019. Published by Elsevier Ltd.)

Jerusalem artichoke is an important natural matrix for inulin production. In this experiment, response surface methodology (RSM) was employed to optimize the spray-drying parameters in order to determine the maximal inulin yield. For this study, three independent variables (heating temperature (Tª, 110-120 °C), creep speed (V, 18-22 rpm) and pressure (P, 0.02-0.04 MPa)) were used in the experimental design. Using the Box-Behnken design, the optimal parameters obtained were: drying temperature 114.6 °C, creep speed 20.02 rpm, and pressure: 0.03 MPa. The inulin yield, water content and particle size of inulin obtained by spray-drying and freeze-drying were compared. In this regard, the spray-dried inulin consisted of a white powder having a fine particle size, and the freeze-dried inulin had a pale-yellow fluffy floc. On the other hand, the drying methods had a great influence on the appearance and internal structure of inulin powder, since the spray-dried inulin had a complete and uniform shape and size, whereas the freeze-dried inulin had a flocculated sheet structure. The analysis showed that the spray-drying led to a higher inulin yield, lower water content and better surface structure than freeze-drying.

Featured Application: Due to the growing importance of inulin in food industry, it is of paramount importance to have appropriate techniques to extract this compound from plant food materials, wastes and by-products. Moreover, using simple, reliable and fast identification and quantification methods in order to verify manufacturer’s information and for quality control purposes, is also of great interest. Therefore, in the present work, a combined trifluoroacetic acid assisted hydrolysis and high performance liquid chromatography equipped with evaporative light scattering detector technique was developed and validated in order to identify and quantify the amount of inulin extracted assisted by ultrasound processing from Jerusalem artichoke root slices as a model plant food matrix. Over the last years, inulin, a fructan mixture consisting of oligosaccharides and polysaccharides, has attracted more and more attention from both food industry and researchers, due to its unique functional properties as a natural resource. Therefore, there is an increased interest in the extraction and quantification of inulin for its valorization from inulin rich plants, wastes and by-products. In this work, ultrasonic treatment was applied for inulin extraction, observing a great impact of extraction temperature and ultrasonic power on the inulin content in the obtained extracts. A combined process including trifluoroacetic acid (TFA)-assisted hydrolysis and analysis with high performance liquid chromatography equipped with evaporative light scattering detector (HPLC-ELSD) was developed to quantify inulin content. The effect of hydrolysis parameters was investigated, obtaining the optimal conditions after using TFA at a concentration of 1 mg/mL, hydrolysis temperature of 90 °C, and hydrolysis duration of 60 min. The good linearity (>0.995), precision, recovery (100.27%), and stability obtained during the validation process showed that this developed method allows the quantification of total inulin content in the samples analyzed. This combined method may also contribute to the investigation of the functional properties of inulin (e.g., as prebiotic). [ABSTRACT FROM AUTHOR]

Jerusalem artichoke is an important plant for industrial inulin production. Jerusalem artichoke extract was clarified by ultra-filtration. Tests were performed to investigate effects of membrane pore size and operation conditions (trans-membrane pressure and rotation speed) on filtration kinetics and membrane-fouling mechanism. Membrane fouling was proved the main filtration resistance for a 20-kDa membrane, while concentration polarization-induced resistance was dominant for 30-, 50-, and 100-kDa membranes. Despite their similar filtration behavior, the 50-kDa membrane, compared to the 100-kDa membrane, led to less protein content (impurity) in the filtrate. Studies with the rotation speed varied from 0 to 1600 rpm and trans-membrane pressure from 0.2 to 0.4 MPa demonstrated that stirring was essential for elimination of membrane fouling. Competition of driving force and fouling was justified when trans-membrane pressure increased from 0.3 to 0.4 MPa. Filtrate analysis including protein removal, turbidity, and inulin purity revealed that ultra-filtration using the 50-kDa membrane with a trans-membrane pressure of 0.3 MPa and a rotation speed of 800 rpm was able to clarify the Jerusalem artichoke extract, removing 99% protein, and obtain a filtrate with inulin purity of 98%. [ABSTRACT FROM AUTHOR]

Inulin constitutes an important food ingredient, widely used for its fiber content, and its ability to substitute fat and sugar ingredients. Traditionally, industrial inulin production from chicory roots requires high extraction temperature (70–80 °C) and long extraction time (1–2 h). This conventional extraction is generally accompanied with the presence of a large amount of impurities in the extracted juice, mainly due to the application of high temperature, requiring thus further purification steps. To overcome these issues, developing novel extraction technologies, consuming less energy, faster, and providing high yield and purity, is of paramount importance to meet the requirements of a green extraction concept. In this review, the feasibility of using conventional and new promising technologies (enzyme assisted extraction, ultrasounds, microwaves, supercritical fluid extraction, and pulsed electric fields) to recover inulin from plant food materials and by-products from an environmental and economical point of view will be discussed. Industrial relevance Inulin is widely used in food industries mainly due to its ability to substitute fat and sugar ingredients. However, the current industrial recovery process of this molecule is mainly carried out by diffusion in hot water (70–80 °C), followed by a relatively complex purification process, due to the presence of a large amount of impurities generated by the application of high temperatures. The need for obtaining greener, sustainable, and viable processes has led food scientists to develop new processes in full correspondence with the green extraction concept based on the use of non-conventional technologies (i.e. pulsed electric fields, ultrasounds, microwaves, etc). The submitted review discusses the potential of some of these new promising technologies to allow the industrial sustainability and green recovery of inulin, which have as benefits: energy- and time-saving along with higher yields and milder temperatures, reducing thus the subsequent purification steps. [ABSTRACT FROM AUTHOR]

Damage of chicory tissue by combined electroporation and ohmic heating is studied for better solute extraction. Moderate (400-1000 V/cm) and high (10,000 V/cm) PEF treatments were applied varying pause duration between the trains of individual pulses. Ohmic heating was induced with increase of the number of trains N. Temperature dependence of tissue damage degree Z is evaluated for the different PEF intensities. With higher ohmic heating, chicory tissue is faster and better damaged. Electric field strengths of 600-800 V/cm combined with ohmic heating permit to enhance noticeably the solute extraction from chicory tissue. The solute diffusivity D for the different PEF treatments, is nearly the same for same values of Z. Chicory tissue treated to the same damage degree (Z=0.8-1.0) using different PEF conditions (800,1000 and 10,000 V/cm) has nearly the same diffusivity. Combined electroporation/ohmic heating pretreatment by moderate PEF (400-1000 V/cm) presents an interesting alterative for the treatment of high product throughputs (e.g. in the case of inulin production from chicory). [ABSTRACT FROM AUTHOR]

Abstract: Membrane fouling and flux decline are important problems in chicory juice clarification by membrane process for inulin production. In this study, a rotating disk module (RDM) equipped with four micro- and ultra-filtration membranes was used to treat raw chicory root extract, and the permeate flux behavior at high-shear conditions was investigated. Increasing disk rotating speed can reduce concentration polarization and cake fouling, and thus improve permeate flux. However, a moderate rotating speed of 1000rpm was a good compromise between energy saving and polarization/cake layers control, while a higher disk rotating speed can be used at regular intervals for on-line membrane cleaning. Threshold and limiting fluxes were determined in chicory juice clarification at 1000rpm and 50°C by pressure stepping experiments, and they were almost independent of pore size, permeability and fouling extent, with ranges of 130–140Lm−2 h−1 for threshold and 155–168Lm−2 h−1 for limiting flux. Below threshold flux, filtration resistance is independent of flux, while above it, membrane fouling increases with increasing permeate flux. This work confirmed that threshold flux criterion was also applicable to high-shear microfiltration and ultrafiltration, and size-dependent shear-induced and Brownian back diffusions played an important role in such filtration resistance transition. Moreover, both limiting flux and flux fluctuations should be avoided in practical applications because they cause high fouling and flux decline. [Copyright &y& Elsevier]

Abstract: Qualitative characteristics and dead-end ultrafiltration behavior of chicory juice obtained at different temperatures from untreated and pulsed electric field (PEF) treated chicory roots are investigated. The chicory juices obtained at lower temperatures (30 and 60°C) from PEF treated chicories are less colorized, have lower turbidity, lower protein content, and higher purity than conventional juice obtained at 80°C. The ultrafiltration behavior of the untreated and PEF treated chicory juice was studied in the dead-end filter cell under different pressures (1, 2 and 4bars) and with stirring at 500rpm. Three types of polyethersulfone membranes with MWCO of 150, 50 and 5kDa were used. The membrane with MWCO of 50kDa produced the most purified filtrate, while the membrane with lower MWCO (5kDa) produced less purified filtrate probably due to the partial retention of inulin molecules. The increase of TMP from 1 to 2 bars increased the filtration flux and the juice purity. The ultrafiltration behavior of obtained chicory juices was successfully described by the filtration model with intermediate blocking mechanism. [Copyright &y& Elsevier]

Abstract: Clarification is the first step of inulin production from chicory juice, and membrane filtration as an alternative can greatly simplify this process, increase juice yield, improve product quality, and reduce the cost and waste volume. In this study, a rotating disk module (RDM) was used to investigate the clarification of chicory juice by four micro- and ultrafiltration membranes. Compared with dead end filtration, the RDM had a much higher permeate flux and product quality. High rotating speeds produced high permeate fluxes and reduced flux decline, because of the strong back transport of foulant from fouling layer to feed solution. At high rotating speeds of 1500–2000rpm, the permeate flux increased with membrane pore size and transmembrane pressure (TMP), while at low rotating speeds (<1000rpm), permeate flux was independent of membrane type and TMP due to a thick deposited fouling layer as a dominant filtration resistance, while carbohydrate transmission decreased at higher TMP because of denser cake layer as an additional selective membrane. The highest carbohydrate transmission (∼98%) and desirable permeate turbidity (2.4NTU) was obtained at a TMP of 75kPa and a rotating speed of 2000rpm for FSM0.45PP membrane. With the RDM, the Volume Reduction Ratio (VRR) could reach 10 with a high permeate flux (106Lm−2 h−1) in the concentration test, and permeate was still rich in carbohydrate and well clarified. Chemical cleaning with 0.5% P3-ultrasil 10 detergent solution was able to recover 90% water flux of fouled membrane. [Copyright &y& Elsevier]

A pilot study for the pulsed electric fields (PEF) assisted countercurrent diffusion of inulin from chicory roots is presented. The influence of PEF parameters (electric field intensity E = 600 V cm−1, treatment duration tPEF = 10-50 ms) and diffusion temperature (varied between 30 and 80 °C) on soluble matter extraction kinetics, inulin content of juice, and pulp exhaustion are investigated. The draft (liquid to solid mass ratio) was fixed at 140%, similar to the industrial conditions. PEF treatment facilitates extraction of inulin at conventional diffusion temperature (70-80 °C), and diffusion temperature can even be reduced by 10-15 °C with comparable juice inulin concentration. Less energy consumption can be achieved by reducing PEF treatment duration to 10 ms, which is observed sufficient for effective extraction. [ABSTRACT FROM AUTHOR]

Jerusalem artichoke is widely used as raw material for industrial production of inulin. Pressing (compression) and diffusion are two effective technologies for bio-compounds' recovery from plants. In this work, pulsed electric field (PEF) treatment at 400, 600, and 800 V/cm during 100 ms was applied to facilitate juice and solutes recovery from Jerusalem artichoke. The application of PEF led to electroporation of cell membranes and enhanced the tissue compression/juice expression and solutes diffusion. The consolidation coefficient (calculated by application of semi-empirical model) of PEF treated sample at 800 V/cm was 6.50 × 10−7 m2/s, which is significantly higher than that of untreated sample (5.02 × 10−9 m2/s) and close to that of freeze-thawed sample. Diffusion experiments with PEF treated samples were carried out at 25, 50, and 75 °C. A PEF treatment of Jerusalem artichoke at 800 V/cm led to a similar diffusion behavior at 25 °C, compared to diffusion behavior obtained from untreated sample at 75 °C. [ABSTRACT FROM AUTHOR]