Optimisation of inulin extraction from globe artichoke (Cynara cardunculus L. subsp. scolymus (L.) Hegi.) by electromagnetic induction heating process

In this study, a D‐optimal design was used to optimise the extraction process conditions of inulin with a high degree of polymerisation from Globe artichoke heart (Cynara cardunculus L. subsp. scolymus (L.) Hegi.), using electromagnetic induction heating (EMIH) as a new extraction process. Four factors were simultaneously studied which were the extraction temperature (55–90 °C), the extraction time (30–120 min), the weight ratio (plant material dry weight/volume of distilled water: 5–10%) and the mode of heating (conventional or electromagnetic induction heating). It was found that the second‐order polynomial models developed by the response surface methodology (RSM) describe adequately the relationship between the factors and responses (extraction yield, viscosity and solubility of inulin). The optimum extraction conditions that led to a maximal extraction yield (45.98%) and an optimal viscosity (3.25 mL g^?1) of extracted inulin are temperature of 89.49 °C, extraction time of 120 min and a 5.01% of weight ratio using EIMH process. Fourier Transform InfraRed spectroscopy spectrum of the extracted inulin was identical to that of the native inulin. The analysis of the extract by thin‐layer chromatography confirms the absence of pectin in the final product, as well as the X‐ray diffraction analysis exhibits a semi‐crystalline structure of the biopolymer.     

Molecular structure and physicochemical properties of Hylon V and Hylon VII starches illuminated with linearly polarised visible light

Aqueous suspensions (30 g/100 g) of Hylon V and Hylon VII high amylose corn starches were illuminated with linearly polarized visible light for 5, 15, 25 and 50 h. For each native and illuminated starch sample, weight average molecular weight, M_w, and hydrodynamic radius, R_g, of starch polysaccharide molecules were measured by high pressure size exclusion chromatography coupled with multiangle laser light scattering and refractometric detectors (HPSEC-MALLS-RI). Additionally, X-ray diffraction patterns, intrinsic viscosity, kinetic of alpha-amylolysis together with iodine binding properties and distribution of amylopectin structural units were established for each starch sample. Changes in molecular weight M_w of starch polysaccharide chains eluted under whole polysaccharide peaks and values of intrinsic viscosity of corresponding starch samples observed in the course of illumination indicated that illumination of both starches studied, with linearly polarized visible light (LPVL), induced first depolymerysation followed by repolymerisation reaction of starch polysaccharide chains. Illumination induced rearrangements of the molecular structure of polysaccharide chains of illuminated Hylon V and Hylon VII starches led to significant changes of their physicochemical properties as compared with native starches.     

Characterisation of pectins extracted from banana peels (Musa AAA) under different conditions using an experimental design

An experimental design was used to study the influence of pH (1.5 and 2.0), temperature (80 and 90 °C) and time (1 and 4 h) on extraction of pectin from banana peels (Musa AAA). Yield of extracted pectins, their composition (neutral sugars, galacturonic acid, and degree of esterification) and some macromolecular characteristics (average molecular weight, intrinsic viscosity) were determined. It was found that extraction pH was the most important parameter influencing yield and pectin chemical composition. Lower pH values negatively affected the galacturonic acid content of pectin, but increased the pectin yield. The values of degree of methylation decreased significantly with increasing temperature and time of extraction. The average molecular weight ranged widely from 87 to 248 kDa and was mainly influenced by pH and extraction time.     

Influence of Jet‐Cooking Temperature and Ionic Strength on Size and Structure of Cationic Potato Amylopectin Starch as Measured by Asymmetrical Flow Field‐Flow Fractionation Multi‐Angle Light Scattering

Asymmetrical flow field‐flow fractionation (AsFlFFF) in combination with multi‐angle light scattering (MALS) was applied to cationic potato amylopectin (CPAP) to investigate how molar mass, root‐mean‐square (r.m.s.) radius and shape was influenced by different conditions of jet‐cooking. The effect of different jet‐cooking temperatures in the range 110°C – 140°C was studied in an excess steam jet‐cooker. This equipment is used in the industry for dissolution of starch and starch derivatives before technical application. The effect of different ionic strengths conditions was examined in the range of 10–200 mM. The weight‐average molar mass decreased from about 34×10⁷ g/mol to 2.6×10⁷ g/mol when the jet‐cooking temperature was increased from 110°C to 140°C. Concurrently the root‐mean‐square radius decreased from ca 380 nm to 90 nm. The decrease in size was reflected by a decrease in viscosity with increasing temperature. The root‐mean‐square radius was reduced when increasing the ionic strength. This decrease in size was correlated with a decrease in viscosity. Conformation and Kratky plots showed that at low ionic strength (≤ 10 mM) CPAP behaved as a flexible chain with high degree of branching, close to hyperbranching. Increase of the ionic strength gave a more compact structure and changes in the internal structure were observed as well. Consequently, by using AsFlFFF – MALS the effect of technical processing on the molar mass, molecular radius, conformational structure, and shape could be determined in a size region where standard methodology commonly fails.     

Elimination of aggregates of (1→3) (1→4)-β-D-glucan in dilute solutions for light scattering and size exclusion chromatography study

Methods for eliminating aggregates of cereal (1→3) (1→4)-β-D-glucan in dilute solutions were investigated using dynamic light scattering and size exclusion chromatography. Wheat β-D-glucan samples were selected and dissolved in various solvents under different preparation conditions. The molecular size distribution was monitored by dynamic light scattering measurement. In most of the solutions, there were two well separated species of different average sizes. It appeared that the specie with smaller average size represented the un-aggregated molecules (unimers) and the specie with larger particle size corresponded to the aggregates. The results showed that heat treatment, filtration, ultrasonication, and the use of urea solution (up to 6 M) could not eliminate aggregates completely. However, the percentage of aggregates in aqueous NaOH solution decreased significantly with the increase of NaOH concentration. In 0.5 M NaOH solution, no aggregation was detectable by dynamic light scattering measurement. Both dynamic light scattering and HPSEC data showed that wheat β-D-glucan was stable in 0.5 M NaOH solution without any noticeable degradation when stored at 25 °C for 12 h. The results of present study suggested that 0.5 M NaOH solution is a suitable solvent for cereal β-D-glucans. Using this solvent, the molecular characteristics of wheat β-D-glucan was studied by both dynamic and static light scattering. The weight average molecular weight (M_w), radius of gyration (R_g), hydrodynamic radius (R_h), and the second virial coefficient (A₂) were obtained with the values of 3.29×10⁵ g/mol, 45.6 nm, 26.2 nm, and 1.04×10⁻³ cm³ mol/g² respectively. This study also confirmed that wheat β-glucan in solution exhibited a random coil conformation.     

Characterization and functional properties of soybean high-molecular-mass polysaccharide complex

Soybean soluble polysaccharide (SSPS), extracted from the by-product obtained during isolation of soybean protein, is an anionic polysaccharide that stabilizes milk proteins under acidic conditions. We developed a high-molecular-mass complex of SSPS cross-linked via phosphate (SSPS-HC; absolute molecular weight = 2850 kg/mol, radius of gyration = 106 nm), and found that it has different protein stabilization properties when compared with the original SSPS (absolute molecular weight = 550 kg/mol, radius of gyration = 36 nm). The objective of this work was not only to study the rheological properties of SSPS-HC, but also clarify its protein-stabilizing properties in comparison with SSPS; if molecular mass or negative charge affected protein dispersion. Irrespective of high-molecular-mass, SSPS-HC possessed similar rheological properties to SSPS such as low viscosity in aqueous solution. The absolute negative charges of SSPS-HC measured by a zeta potential analyzer at pH range of 2.0–7.0 were higher than those of SSPS. Acidified milk drinks prepared with 8.4% non-fat milk solids and 0.4% SSPS-HC or SSPS showed low viscosity and small protein particle size, and did not aggregate for 14 days. The thickness of the hydrated layer, which was formed on the surface of protein particles by SSPS molecules measured after hemicellulase treatment with DLS (dynamic light scattering), was estimated to be about 89 nm for SSPS-HC and 33 nm for SSPS. These numerical values were in good relation to the molecular diameter of SSPS-HC and SSPS in aqueous solution measured by DLS and AFM image, and suggested that protein particles were dispersed and the hydrated monolayer made on the surface of protein particles by SSPS-HC or SSPS molecules prevented aggregation. However, stabilizing pH ranges were different with stability of SSPS-HC at pH range of 4.0–4.8 and stability for SSPS at pH range of 3.6–4.2. In addition to the difference in the molecular mass and absolute negative charge, the phosphate groups of SSPS-HC were possibly influenced on the protein-dispersing property approximately at isoelectric point of milk protein; SSPS-HC prevent aggregation of casein by accelerating solubility of calcium phosphate under acidic conditions as is already reported in the starches phosphorylated.     

Identification and Analysis of the Constituents in an Aqueous Extract of Tricholoma Matsutake by HPLC Coupled with Diode Array Detection/Electrospray Ionization Mass Spectrometry

The main constituents in an aqueous extract of Tricholoma matsutake (Tm) were identified by high‐performance liquid chromatography coupled with diode array detection and electrospray ionization time‐of‐flight mass spectrometry (HPLC‐DAD/TOF‐MS) and ion trap mass spectrometry (HPLC‐DAD/Trap‐MSn). The main factors in the extraction process which affect the yields of nutrients were optimized by single‐factor experiments and orthogonal experiment design. In total, 12 constituents were identified from the aqueous extract of Tm, including tyrosine, cytidine, uridine, eritadenine, phenylalanine, nicotinamide, inosine, guanosine, tryptophan, adenosine, 5′‐deoxy‐5′‐methylthioadenosine and riboflavin. The optimized extraction conditions were: the ratio of water to sample was 10 : 1 (v/w), Tm was extracted by ultrasonic‐assisted extraction for 10 min, followed by water bath heating at 60 °C for 1 h. Among these extraction factors, the heating temperature is significant based on analysis of variance (ANOVA). The yields of nutrients were affected dramatically at high temperature leading to the loss of nutrients, especially for nucleosides and some amino acids.     

The antioxidant capacity of polysaccharide from Laminaria japonica by citric acid extraction

An optimal citric acid extraction condition (pH 2.0; extraction temperature: 120 °C; extraction time: 3 h) was developed to obtain polysaccharide from Laminaria japonica. The yield of polysaccharide was 13.31 ± 0.08%, with IC₅₀ value of DPPH radical scavenging activity of 0.98 ± 0.01 mg mL^?1. The viscosity of polysaccharide extracted by citric acid (LJPA) was eight times lower than that of polysaccharide extracted by hot water (LJPW), which may be attributed to the low average molecular weight of LJPA (17.12 kDa). Gas chromatography analysis indicated that LJPA was composed of rhamnose, fucose, xylose, manose, glucose and galactose with relative molar percentages of 4.51%, 20.27%, 12.43%, 12.81%, 10.29% and 39.69% respectively. Furthermore, LJPA exhibited significantly higher antioxidant capacities including oxygen radical absorbance capacity (ORAC), ABTS radical scavenging activity and reducing power than LJPW. Citric acid extraction showed a positive influence on the polysaccharide degradation and antioxidant capacities of L. japonica.     

Physical Properties of Yogurt: A Comparison of Vat Versus Continuous Heating Systems of Milk

Milk was processed by vat (85°C for 10 to 40 min), high temperature, short time (98°C for .5 to 1.87 min), and ultra-high temperature (140°C for 2 to 8 s) heating systems and made into yogurt. Yogurt firmness ranged from 90 to 104 g force for vat treatments, 74 to 96 g for high temperature, short time treatments, and 47 to 65 g for ultra-high temperature treatments. Planned contrasts between heating systems indicated significantly higher yogurt firmness and viscosity for vat versus high temperature, short time and ultra-high temperature systems. Yogurt from high temperature, short time milk showed the highest water-holding capacity, followed by ultra-high temperature and vat treatments. Correlation coefficient between yogurt firmness and whey protein denaturation was .83 and between apparent viscosity and whey protein denaturation was .89. Sensory evaluation indicated an overall preference for yogurt made from high temperature, short time (1.87 min) milk.     

Structure of β-lactoglobulin microgels formed during heating as revealed by small-angle X-ray scattering and light scattering

We have investigated the structure of microgels formed during heating of demineralized β-lactoglobulin (βlg) solutions at pH 5.9 by small-angle X-ray scattering (SAXS) and light scattering. First, unheated βlg solutions were characterized at different pH values between 2.0 and 7.0. At pH 5.9, βlg solutions contain mainly dimers (with a radius of approx. 2 nm), which coexist with a small number of larger oligomers (approx. 4 nm). Afterwards, βlg microgels, which form upon heating, were studied. They exhibit an average hydrodynamic radius around 130 ± 20 nm and an average molar mass around 7 × 10⁸ g mol⁻¹. We followed the temporal evolution of the various structures that form after different heating times using subsequent SAXS measurements of the entire sample, the soluble fraction where the βlg microgels were removed, and the solvent. After an hour of heating at 85 °C the maximum yield of the βlg microgels (ca. 70%) is almost reached. Interestingly, the SAXS data show a correlation peak corresponding to a characteristic distance of about 9 nm, indicating an internal organization of the microgels. During the heating procedure the pH increases from pH 5.9 to approximately 6.6, which is induced by the partial conversion of βlg into βlg microgels that exhibit less buffering capacity than native protein. The remaining soluble fraction consists of native βlg and some small aggregates, whose number increases on the cost of native βlg as heating time proceeds. We propose that the formation of these lower molecular mass aggregates is triggered by the increased pH.     

Extraction of oil from tiger nut (Cyperus esculentus L.) with supercritical carbon dioxide (SC-CO2)

Supercritical carbon dioxide (SC-CO₂) was used to extract oil from tiger nuts and the physicochemical properties and the impact of extraction conditions [i.e., temperature (40 °C–80 °C), pressure (20–40 MPa) and time (60–360 min)] on the oil yield were studied. The response surface analysis results revealed that the oil yield was significantly (P < 0.05) influenced by the main effect of the extraction pressure, extraction time and their quadratic effects respectively. However, the interaction between the extraction temperature and time had no significant (P > 0.05) effect on the oil yield. The highest oil yield was 26.28 g/100 g sample after 210 min of extraction time at 30.25 MPa and 60 °C respectively. The fatty acid composition of oils obtained by SC-CO₂ and Soxhlet showed marked variation. Also, the fatty acid composition varied depending on the operating conditions. The viscosity of the oil decreased with the increase in temperature.     

Determination of physicochemical properties of sulphated fucans from sporophyll of Undaria pinnatifida using light scattering technique

The weight average molecular weight (M_w) of the intact sulphated fucans extracted with water from the sporophyll of Undaria pinnatifida without acid treatment was determined using the high performance size exclusion chromatography coupled to multiangle laser light scattering and refractive index detection (HPSEC-MALLS-RI) system. The effects of different heating conditions on the determination of M_w were investigated. The extracted intact fucoidans mostly consisted of carbohydrates (54.9%) and sulphate (41.5%) with monosaccharide composition of 78.8% fucose and 21.2% galactose. The M_w of the intact fucoidans was reduced from 23,600 to 5200 kDa when heated in boiling water for 1–15 min. Microwave heating for 30 s decreased the M_w of fucoidans to 2400 kDa despite no significant polymer degradation. The results indicate that the 30 s-microwave heating yielded a more accurate M_w value of the intact fucoidans than any other heat treatments used in this study.     

Husk Tomato (Physalis ixocarpa Brot.) Waste as a Promising Source of Pectin: Extraction and Physicochemical Characterization

Husk tomato (Physalis ixocarpa Brot. var. Rendidora) waste was evaluated as a source of specialized pectin, and pectin extracted from this waste was characterized physicochemically. Fruit was blanched for 10 or 15 min and extracted in 0.1 N HCl for 15 to 25 min. Extracted pectin was subjected to physicochemical analysis. For all extraction conditions, the percentage of anhydrogalacturonic acid exceeded 60%, indicating that husk tomato was a good source of pectin. The degree of esterification of pectin molecules was 63% to 91%. The amount of extracted pectin decreased with increasing extraction time. The apparent viscosity of husk tomato pectin showed the characteristic behavior of pseudoplastic fluids. Neutral sugars were identified, and the amounts of 6 sugars (fucose, rhamnose, arabinose, galactose, glucose, and xylose) were quantified. Sugars identified in husk tomato pectin and present in the Rhamnogalacturonan I region, arabinose, galactose, and rhamnose suggest a highly branched structure, which will influence its future applications. Molecular weight values were 542 to 699 kDa, exceeding molecular weight values reported for commercial citrus pectins from 134 to 480 kDa. The extraction process significantly (P < 0.05) influenced the physicochemical properties of pectin. Up to 19.8% from the total amount of pectin in the husk tomato was extracted by 10 min of blanching and 20 min of a more heat treatment. Our findings indicate that husk tomato can be a good alternative source of pectin having highly distinctive physicochemical characteristics.     

Physicochemical properties of sugar beet pulp pectin by pulsed electric field treatment

This research focused on pulsed electric field (PEF) modification of pectin from sugar beet pulp. Experimental parameters including electric field intensity (18–30 kV cm^?1) and pulse time (806–2418 μs) were used, and the physicochemical properties of PEF‐treated pectin were evaluated by various instrumental techniques such as scanning electron microscopy, X‐ray diffraction, dynamic light scattering and Fourier transform infrared spectroscopy. The results showed that the degree of esterification, viscosity average molecular weight and particle size of pectin decreased with the increase in electric field intensity and pulse time. Meanwhile, some sharp interstices were shown on the surface of pectin, and its crystalline regions were destroyed after being treated with PEF. Results revealed that PEF technology is an effective method to obtain low‐molecular‐weight pectin with different degrees of esterification and obtain a desired production in food application.     

Solution behavior of barley β-glucan as studied with asymmetrical flow field-flow fractionation

Physicochemical properties of cereal β-glucans, associated with beneficial health effects, are related to their solution behavior and possibly to their propensity to form aggregates. Such properties are often analyzed with methods that may influence the aggregates per se. In this paper, the effect of processing on solution behavior of pure barley β-glucan was studied using asymmetrical flow field-flow fractionation (AsFlFFF), a method which is capable of analyzing the present aggregates. Molar mass distributions were determined by in-line multi-angle light scattering and refractive index detectors. Unprocessed samples had a main fraction of aggregates with a weight-average molar mass of 2.8 × 10⁶ g/mol. Microwave heating to 100 °C reduced the largest aggregates, while heating to 121 °C prominently decreased the molar mass. Frozen storage for 1 week did not influence the aggregation, but repeated freeze-thaw cycles changed the structure of aggregates in a way that suggests cryogelation. The influence of processing conditions on solution behavior might explain why differently processed food products containing β-glucan have given different health effects. Experiments with the aim to eliminate aggregates demonstrated that filtration (0.45 μm) prior to analysis resulted in disruption of the largest aggregates, indicating that these aggregates will not be detected when filtration is used. Dissolution in NaOH solution, one of few solvents reported to eliminate aggregates, resulted in retained molar mass. Using AsFlFFF to study the solution behavior of β-glucans is a gentle method to analyze subtle changes of physicochemical properties.     

Functionality and yield of pectin extracted from Palmyra palm (Borassus aethiopum Mart) fruit

Large numbers of fruits from Palmyra palm (Borassus aethiopum Mart), a common, native tree of tropical regions, are underutilized and left to spoil. This work was conducted to assess pectin content of Palmyra palm fruit, and to develop a reliable protocol for pectin extraction. Yield and galacturonic acid content of Palmyra palm fruit soluble solids were investigated at various pH (natural pH of 5.2–5.5, 2.5, 7), time (30–120 min) and temperature (70 °C, 80 °C, 90 °C). Yield and galacturonic acid content of extracted soluble solids were strongly dependent (p < 0.0001) on temperature, time and pH of extraction and ranged from 47 to 149 g kg⁻¹ and 682 to 880 g kg⁻¹ dry weight, respectively. High galacturonic acid (808–852 g kg⁻¹) were obtained at 70 °C and 90 °C under natural pH; at 70 °C pH 7 and pH 2.5 at all temperatures studied. Analysis of pectin extracted at natural pH (30 min, 90 °C) revealed highly esterified pectin with good gelling and emulsifying properties. Production of galacturonic acid of more than 650 g kg⁻¹ dry weight indicates that Palmyra palm fruit could serve as an excellent raw material for industrial pectin production.     

Sedimentation Field Flow Fractionation Combined with Multi Angle Laser Light Scattering Applied for Characterization of Starch Polymers

Sedimentation Field Flow Fractionation in combination with multi angle laser light scattering was applied to fully destructured potato and waxy corn starches to investigate the molecular weight and radius distributions of the starch components. In a range of radii betwen 50 and 500nm, information could be obtained about the influence of the medium conditions on the distributions. The averages of molecular weight and particle radius were found to decrease when holding the solution at a given temperature for an extended period of time (from 20min up to 60min) and when the temperature was increased (from 160°C up to 175°C). The molecular weight and radii of gyration of the dissolved starch species typically panged from 10⁶ to 10⁹ daltons and 50nm-500nm respectively. Changes in the distributions due to different conditions during the dissolution process where also recognized by changes in the shape of the distribution curve. Thus the applied technique gave satisfactory results in a high molecular weight region where SEC fails.     

Comparison of polysaccharide degradations by dynamic high-pressure homogenization

The mechanical degradation of polysaccharides was investigated using dynamic high and ultra-high-pressure homogenization (HPH). The objectives were to reduce the molar mass of polymer chains, and simultaneously, the apparent and intrinsic viscosity of polysaccharides in solution. The influence of homogenization pressure (up to 200 MPa) and cycles was compared on polysaccharides with different physical and structure properties: namely, guar gum, hydroxyethylcellulose (HEC), sodium carboxymethylcellulose (Na-CMC), sodium alginate (Na-alginate) and gum arabic. HPH was applied on semi-dilute solutions. The apparent changes in molar mass, gyration radius and intrinsic viscosity were deduced from size exclusion chromatography coupled on-line with multi-angle laser light scattering, differential viscometer detector and differential refractive index detector (SEC/MALS/DV/DRI), while the evolution of the critical overlap concentration (C^∗) was obtained by viscosimetry. A method based on a succession of homogenization cycles and polymer pre-concentration steps was developed to determine the minimum molar mass achieved at constant pressure. Molar mass, and intrinsic viscosity were shown to fall simultaneously while logically C^∗ increased during HPH for all polysaccharides, except gum arabic, probably because of its globular and branched structure. This highlights that the differences of polysaccharide structures and conformation (linear, branched…) exhibit a stronger impact on HPH treatments than polymer charge or molar mass. Finally, via an empirical approach linking the decrease of both molar masses and viscosities, we have evidenced a specific scaling exponent that should characterize the flexibility of the treated polymer (i.e. its ability to be degraded by HPH).     

Pectin Extraction from Lemon By-Product with Acidified Date Juice: Effect of Extraction Conditions on Chemical Composition of Pectins

Mixtures of date and lemon pectins were extracted from lemon by-product with acidified date juice under different conditions of temperature, pH and time. Individual pectins from date and lemon, respectively, were also extracted using the same experimental conditions, then analysed and compared to pectin mixtures. It was found that the use of extreme conditions resulted in higher galacturonic acid content, lower degree of methylation, lower neutral sugar content, lower molecular weight and darker colour pectins. Examination of the individual neutral sugars showed that the main ones were galactose (1.6–5.4%), arabinose (1.6–4.2%) and rhamnose (0.5–0.8%). The Gal A/Rha molar ratios varied from ∼53 to ∼149. Moreover, mixture of pectin extracted at the optimal extraction conditions (84.34 °C, pH 2.8 during 3 h 34 min) had interesting properties, with a high galacturonic acid content (63.4%), low degree of methylation (∼35%) and a mass molecular weight of about 243 kg/mol.     

Effects of Blanching on Some Physical Properties and Processing Recovery of Sweet Corn Cobs

The effects of the blanching process of sweet corn on shearing stress, shearing energy, and processing recovery of kernels as well as weight and dry substance of kernels and cobs were studied. Sweet corn cobs were blanched in water, where blanching time ranged from 2 to 8 min and temperature ranged from 75 to 100 °C. Nonblanched cobs (fresh cobs) were used as control samples. It was found that all analyzed variables were significantly affected by blanching time and temperature. The average values of all analyzed variables, except moisture which decreased, increased with increasing of the blanching time and temperature. Changing the blanching time and temperature affected the dry substance of kernels and cobs, kernel and cob mass, recovery processing by increasing it, as well as the average values of shearing stress and shearing energy by decreasing them.