Effects of pretreatment and drying methods on molecular structure,functional properties and thermal stability of fibre powder exhibiting colour from Centella asiatica L.

Effects of pretreatment and drying methods and particle size on characteristics of fibre powder from Centella asiatica L. leaves were investigated. Thermal stability of oil‐based colour solutions was also assessed. Steaming and combined steaming and alkaline soaking resulted in the powder with more greenness and higher chlorophylls contents, while combined steaming and acid soaking yielded dark yellow powder with lower chlorophylls contents. Chemical soaking led to the powder with decreased water holding capacity and solubility. Vacuum‐drying reduced chlorophylls degradation, hence retention of the greenness of the powder. Increased particle size resulted in decreased lightness of the powder, but in increased lightness of the solutions; water and oil holding capacities of the powder increased with the particle size. Fourier transform infrared (FTIR) spectra and X‐ray diffraction (XRD) patterns of the powder corresponded to its colour and functional property changes. Colour of the solutions changed only slightly upon heating at 80 and 180 °C for 1 h.     

Antioxidant and functional properties of a high dietary fibre powder from carambola (Averrhoa carambola L.) pomace

The use of carambola pomace as a raw material for the production of a high dietary fibre powder (HDFP) was investigated. A face‐centred design was used to study the effects of extraction conditions, namely water‐to‐pomace ratio, time and temperature, on both reducing sugars (RS) and total extractable polyphenols (EPP) contents of fibre concentrate. RS content decreased by increasing extraction times and water‐to‐pomace ratios, while EPP tend to diminish by increasing temperature and contact time (P < 0.01). Selected HDFPs showed an EPP content in the range of 5.0–6.1 g GAE 100 g^?1 dry basis (db), with antioxidant activities between 386.2–443.9 and 204.7–228.6 μmol Trolox equivalents g^?1 db according to FRAP and ABTS assays, respectively. HDFP obtained at 55 °C, 5 min and 2:1 water‐to‐pomace ratio exhibited the highest EPP content, total dietary fibre (84.0% db) and dietary indigestible fraction (61.3% db). This product can be considered as a potential valuable food ingredient considering their oil retention and swelling capacities.     

Improvement of the functionality of a potential fruit insoluble fibre by micron technology

An insoluble food fibre was micronised to different microsizes (6.77–29.5 μm) by three different micron technologies using optimised conditions. The effects of different micronisation treatments and particle sizes on the characteristics and various physicochemical properties of this insoluble fibre were studied. As particle size decreased, the bulk density of the insoluble fibre was significantly (P < 0.05) decreased. A redistribution of fibre components from insoluble to soluble fractions was observed. The treatments, especially the high‐pressure micronisation, effectively (P < 0.05) increased the physicochemical properties (e.g. water‐holding capacity, swelling capacity, oil‐holding capacity, cation‐exchange capacity and glucose‐adsorption capacity) and also the inhibitory activity towards α‐amylase and pancreatic lipase of the insoluble fibre to different extent (from several up to c. fifteenfold). Our results suggested that micronisation treatments would provide an opportunity to improve the functionality of the insoluble fibre and exploit its potential applications as a functional ingredient in fibre‐rich products.     

Functional properties of yellow field pea (Pisum sativum L.) seed flours and the in vitro bioactive properties of their polyphenols

Functional and bioactive properties of yellow field pea (Pisum sativum L) seed flour, protein isolate (PPI), two high fibre products (Centara III, Centara IV), and one high fibre–starch ingredient (Uptake 80), were determined. The whole seed flour had superior water and oil absorption capacities but the high fibre flours had significantly higher (p < 0.05) swelling ability. Centara IV and Uptake 80 had the highest gel clarity while Centara IV gel was the most resistant to freeze–thaw treatment. Polyphenolic constituents were extracted singly or sequentially with aqueous methanol and acetone; the whole pea seed flour and the pea protein isolate had significantly more polyphenolic constituents than the fibre products, which also resulted in higher in vitro antioxidant activities (trolox equivalent antioxidant capacity and diphenyl-picryl hydrazyl free radical scavenging ability). Results of renin- and ACE-inhibitory activities were mixed and did not correspond to the overall polyphenolic content and antioxidant test results, probably indicating the importance of components specific to individual extracts.     

Extrusion improved the physical and chemical properties of dietary fibre from bamboo shoot by-products

Bamboo shoot by-products are regarded as waste and environmental pollutant. This study aimed to improve the functional properties of dietary fibre from bamboo shoot by-products. After CO₂ extrusion, the particle size of CO₂-extruded bamboo fibre was 17.6% lower than that of the control, and its specific surface area was 2.85 times that of the control. The soluble dietary fibre content was significantly increased from 5.64 g/100 g to 11.05 g/100 g (P < 0.05), and the capacities for water holding, swelling and oil holding were remarkably improved. The cholesterol adsorption of CO₂-extruded bamboo fibre was increased from 96.54 μg g⁻¹ to 174.65 μg g⁻¹ (pH 7.0), and its nitrite ion adsorption capacity was increased from 503.33 μg g⁻¹ to 657.27 μg g⁻¹ (pH 2.0). In summary, the structural changes of bamboo fibre such as internal porosity, surface roughening and low crystallinity indicated that its functional properties were improved after CO₂ extrusion.     

Effects of micronisation on the characteristics and physicochemical properties of insoluble fibres

The effects of micronisation on the characteristics and physicochemical properties of (a) an insoluble fibre‐rich fraction (IFRF) prepared from orange peel and (b) cellulose were studied and compared. The results showed that micronisation techniques such as ball milling, jet milling and high‐pressure micronisation could effectively (P < 0.05) reduce particle sizes to microscale, decrease the bulk density and improve the physicochemical properties (water‐holding capacity, swelling capacity, oil‐holding capacity, cation exchange capacity and glucose adsorption capacity) of IFRF and cellulose to different extents (up to 25‐fold). After micronisation the inhibitory effects of these insoluble fibres towards α‐amylase and pancreatic lipase were significantly increased (up to 5.8‐ and 7.8‐fold respectively) and a redistribution of some fibre components from insoluble to soluble fractions was observed. It was concluded that these micronisation treatments, especially high‐pressure micronisation, could effectively improve the functionalities of IFRF and cellulose, which might then be used as potential fibre‐rich ingredients in functional food applications. Copyright © 2006 Society of Chemical Industry     

Effects of pineapple pomace fibre on physicochemical properties of composite flour and dough,and consumer acceptance of fibre‐enriched wheat bread

Pineapple pomace fibre (PF, containing 70.2% total dietary fibre) can be added to increase dietary fibre of wheat bread. This study was performed to evaluate effects of PF added at 0, 5 or 10% (wheat flour‐basis) on physicochemical properties of the composite flour (wheat flour as the control, CPF‐5 and CPF‐10, respectively) and its dough, to evaluate consumer acceptance of CPF breads and to identify factors affecting willingness to purchase of CPF breads. Incorporating PF affected rheological and pasting properties of CPF. Water‐ and oil‐holding capacity of CPF increased (P < 0.05) as PF levels increased. Bread made with CPF‐5 was more acceptable than that with CPF‐10; however, it was not significantly different from the control, having similar specific volume and texture, but having about three times higher total dietary fibre than the control (4.4% vs. 1.5%). Product label and health benefit information potentially affected consumers' willingness to purchase of fibre‐enriched bread.     

Comparison of structural,antioxidant and immuno‐stimulating activities of polysaccharides from Tremella fuciformis in two different regions of China

In this study, we compared the chemical structure, antioxidant and immuno‐stimulating activities of two polysaccharides, TPS–FJ and TPS–SC, extracted from Tremella fuciformis from two of the major cultivation regions of China. TPS–FJ and TPS–SC contained protein and high uronic acid. Average molecular weights of TPS–FJ and TPS–SC were 45 461 and 25 981 kDa, respectively. A triple‐helix conformation was exhibited by TPS–FJ but not by TPS–SC. TPS–FJ and TPS–SC contained same monosaccharides but in different ratios. Both the polysaccharides displayed characteristic polysaccharide bands in their Fourier transform infrared and NMR spectra, shown high water and oil holding capacity, and retained antioxidant potential after simulated gastrointestinal digestion in vitro. TPS–FJ significantly (P < 0.05) stimulated the nitric oxide, tumour necrosis factor‐α and interleukin‐6 production of RAW 264.7 cells with higher reactions than those of TPS–SC in vitro. Thus, Tremella fuciformis polysaccharide can be used as a potential antioxidant and immunomodulatory ingredient in food industry.     

A new nanofibrillated and hydrophobic grafted dietary fibre derived from bamboo leaves: enhanced physicochemical properties and real adsorption capacity of oil

Dietary fibre (DF) has been used for enhancing health benefits for centuries. In this study, an innovative nanofibrillated cellulose (NFC) was obtained by the combined application of high‐density steam flash‐explosion and enzymatic hydrolysis of bamboo leaves. The NFC prepared in this study was characterised by long, well‐defined and distinct NFC fibres, exhibiting excellent functional properties (water retention capacity: 20 g water g^?1, swelling capacity: 97 mL g^?1, oil‐holding capacity: 13 g oil g^?1, and higher adsorption of bile acids and cholesterol). Octenyl succinic anhydride (OSA) was further successfully grafted onto the NFC to improve its hydrophobicity. Thus, the oil‐holding capacity of the NFC reached 18.5 g oil g^?1 and the adsorption of bile acids and cholesterol increased twofold. A gastrointestinal digestion experiment further showed that the nanofibrillated and hydrophobic grafted dietary fibre represented a high‐quality dietary supplement providing enhanced health benefits, highlighted by the strong ability to absorb oil. These results indicate that the OSA‐NFC has a great potential for use as a functional ingredient in food products.     

The effect of cryo-grinding and size separation on bioactive profile of buckwheat hulls

Buckwheat hulls (BWH) are a lignocellulosic material with valuable nutrient contents, especially rutin and dietary fibre, which are worth exploring from a food industry perspective. BWH are also a voluminous material that is difficult to grind to very fine particle sizes, which can be achieved under cryogenic conditions. Therefore, we investigated the effect of fractionation by cryo-grinding and size separation (<56, 56–180 and >180 µm) on the dietary fibre content and bioactive profile of BWH. While we hypothesised that micronisation would increase fibre solubility and release of bioactive compounds, we found that BWH must be fractionated to a size <56 µm to show a significant increase in soluble fibre content (106%), rutin (66%), total free phenolic compounds (94%) and antioxidant capacity (45–63%). Moreover, we have shown that near-infrared spectroscopy combined with partial least squares regression can be easily used for rapid scanning of BWH to select the most suitable pre-processing conditions for maximum nutritional value of this food industry by-product.     

Effect of drying methods on physico-chemical and antioxidant properties of date fibre concentrates

Effects of different drying methods (freeze-, oven- and sun-drying) on physico-chemical properties of date fibre concentrates (DFC) from three potential Tunisian cultivars were investigated. DFC had high contents of dietary fibre (71.01–93.46% dry matter), with high proportions of insoluble dietary fibre. Freeze dried DFC had the highest values of swelling, water holding and oil holding capacities. This drying method gave also the lightest DFC colour. Kentichi fibre produced by freeze-drying had the highest viscosity and the lowest bulkier particles. The present work assessed polyphenol content and antioxidant activity of DFC using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The highest polyphenol content was found for freeze dried DFC, contrary to radical scavenging activity which was not affected by drying methods. Results suggest that freeze dried DFC had the highest potential to be used as a functional ingredient in food products.     

Comparison of Properties of New Sources of Partially Purified Inulin to Those of Commercially Pure Chicory Inulin

Newly developed inulin powders were prepared from roots of Asparagus falcatus (AF) and Taraxacum javanicum (TJ) plants grown in Sri Lanka. Inulin content, analyzed by enzymatic spectrophotometric as well as high‐performance liquid chromatographic methods, showed that AF and TJ inulin powders contain 65.5% and 45.4% (dry wt) inulin, respectively, compared with 72% dry wt in the commercially available chicory inulin. Treating the AF and TJ inulin powders using ion exchange techniques significantly (P < 0.05) reduced their contents of micro (Zn, Cu, Mn, Fe) and macro (Na, K, Ca, Mg) elements. Enzymatic hydrolysis of inulin into fructose and glucose by fructanase, and FT‐IR analyses proved that the developed AF and TJ inulins have characteristic molecular composition similar to commercial inulin. TJ inulin contained significantly (P < 0.05) greater amounts of total phenolics (4.37 mg GAE/g), total flavonoids (2.79 mg QE/g), and antioxidant capacity (833.11 mM TE/g) than AF inulin, which contained 1.33 mg GAE/g of total phenolics, 0.43 mg QE/g of total flavonoids, and 406.26 mM TE/g antioxidant capacity. The current study suggests that the newly developed inulin from AF and TJ roots could be used as an alternative commercial source of inulin for the food industry.     

Properties of soluble dietary fibre from defatted coconut flour obtained through subcritical water extraction

Response surface methodology was employed to optimise the process parameters for subcritical water extraction of soluble dietary fibre (SDF) from defatted coconut flour. The obtained model was applied to predict the optimum response values and verified by validation experiment. The composition, structure, properties and bioactivities of the extracted SDF were studied. Effects of extraction temperature, extraction time, solid–liquid ratio and mesh number on the yield of SDF were investigated. The extraction at 140 °C for 30 min, a solid–liquid ratio of 1:30, and a mesh number of 80 resulted in the extraction rate of SDF of 14%. Moreover, monosaccharide analysis indicated that SDF primarily contains mannose and galactose respectively. As indicated by X-ray diffraction and thermal analysis, SDF has low degree of crystallinity and high thermal stability. Additionally, SDF has high water holding, oil holding and swelling capacities, while exhibits high antioxidant activity against DPPH, ABTS⁺ and ˙OH radicals, as well as high in vitro hypoglycaemic activity. The SDF also exhibits good biofunctions, such as good toxic ions and bile acid salts adsorption. This study demonstrates that defatted coconut flour, which is an inexpensive source of natural dietary fibre, can be suitably used as a functional food ingredient in the food industry.     

Effect of grape dietary fibre on the storage stability of innovative functional seafood products made from farmed meagre (Argyrosomus regius)

Two groups of farmed meagre (Argyrosomus regius) sausages were studied regarding quality changes and antioxidant capacity during a 98‐day storage experiment at 2 ± 2 °C. Control sausages contained 3.9% (w/w) of inner pea dietary fibre (IPDF) and the other group contained 0.9% (w/w) IPDF plus 3.0% (w/w) of antioxidant grape dietary fibre (AGDF). The control and AGDF meagre sausages presented a high nutritional value, given their low caloric content, fatty acid profile, amino acid composition and high DF content. Both products were remarkably stable over storage time. The AGDF had an effective antioxidant capacity, proven not only by the radical scavenging activity (90.0–91.0% vs. 82.1–85.4%) and reducing power (8.13–9.10 mg ascorbic acid equivalent g^‐1 vs. 4.16–4.24 mg ascorbic acid equivalent g^?1) measurements, but also by the lower thiobarbituric acid reactive species (TBARS) values (0.78–1.10 vs. 1.50–2.08 mg malonaldehyde kg^?1) over storage time. AGDF seemed to present antimicrobial effect, since on the 63rd day (beginning of significant microbial growth), the control sausages had more than 3 log CFU g^?1 and AGDF sausages much <3 log CFU g^?1. The sensory assessment pointed to some loss of textural quality, more accentuated in the AGDF sausages.     

Physicochemical properties of pre-treated cuttlebone powder and its potential as an alternative calcium source

This study was aimed to investigate the potential use of pre-treated cuttlebone powder (CBP) as an alternative calcium source by evaluating the physicochemical properties of CBP pre-treated with distilled water (CBP1), 1% acetic acid (CBP2), and 2% sodium hydroxide (NaOH) solutions (CBP3). Proximate analysis revealed ash as the major component of all samples. The presence of phenols, flavonoids, alkaloids, and glycosides were detected but tannins appeared to be absent in cuttlebones. Mineral analysis indicated that CBP was rich in calcium, which means the material may be considered as a potential calcium source for food products or calcium supplements. The bulk density of CBP2 was significantly lower (p < .05) than those of CBP1 and CBP3, and the water holding capacity (WHC) of CBP1 was significantly higher (p < .05) than those of CBP2 and CBP3. The high bulk density, water and oil holding capacities of CBP demonstrated its potential use as a functional food ingredient.     

Chemical composition,functional properties and microstructural characteristics of three kabuli chickpea (Cicer arietinum L.) as affected by different cooking methods

Chickpea is an important food legume and is a major ingredient in many human diets. Chemical composition, physical parameters, functional properties and microstructural characteristics of three kabuli chickpea cultivars and the effects of three cooking methods were investigated. Carbohydrate and protein were two major components in all seeds. Cooking increased fibre, total carbohydrate and total and resistant starch contents, but decreased ash content. Protein and oil levels of the cooked samples either decreased or did not change significantly. Seed weight and density decreased with cooking. Hydration and swelling capacities as well as water absorption and holding capacities of cooked chickpeas were higher than raw samples, with the largest increases in the pressure‐cooked seeds. Seed weights were highly correlated with hydration (r = 0.89) and swelling (r = 0.76) rates. Emulsifying activity, emulsifying stability and foaming capacity of cooked chickpea flours decreased, while foaming stability increased. Chickpea flours had pronounced morphological changes after cooking.     

Influence of Oven-Drying Temperature on Physicochemical and Functional Properties of Date Fibre Concentrates

Agri-food by-products rich in dietary fibres may be used as feeds and health foods. Owing to its high fibre content, date flesh could be useful in human nutrition. It is interesting to study the influence of oven-drying temperatures of date fibre concentrates (DFC) on their physicochemical and functional properties for possible use as a potential fibre source in the enrichment of food. DFC from 11 Tunisian date cultivars were dried at different temperatures (40, 50 and 60 °C) and analysed regarding proximate composition (moisture, ash, protein and lipids), physicochemical (water activity (a _w), pH) and functional properties (water holding capacity (WHC), swelling capacity (SC), oil holding capacity (OHC) and emulsifying capacity (EC)). DFC dried at different temperatures showed interesting functional characteristics such as hydration properties, high OHC (2.73–4.60 g oil/g dry fibre) and EC (5.93–12.87%) values. Although drying temperatures promoted little modifications affecting the physicochemical properties of DFC, significant decreases in WHC, SC and EC of DFC were noticed at the highest temperature (60 °C) for most of the date varieties. The observed influence of drying temperature on functional DFC properties calls for the use of low temperature in order to obtain DFC as suitable food ingredient.     

Response surface methodology for optimisation of soluble dietary fibre extraction from sweet potato residue modified by steam explosion

To make better use of sweet potato residue (SPR), a new pretreatment method, steam explosion (SE), can increase its content of soluble dietary fibre (SDF). Response surface methodology (RSM) was used to determine the SE variables for optimum SDF yield. The optimal conditions were a steam pressure of 0.35 MPa, a residence time of 121 s and a sieving mesh size 60. Under the optimised conditions, the content of SDF from SPR reached 22.59 ± 0.35%, an increase of 18.78% compared with that (3.81 ± 0.62%) from untreated SPR. The water‐holding capacity, oil‐holding capacity (OHC) and swelling capacity of SDF were improved by SE. Scanning electron micrograph (SEM) images demonstrated that SDF had become poriferous, loose and dilatants after SE treatment. This technology provides an efficient process for increasing the industrial production of SDF from SPR.     

Influences of pretreatment and drying methods on composition,micro/molecular structures and some health‐related functional characteristics of dietary fibre powder from orange pulp residues

Influences of pretreatment methods (washing, blanching, soaking in ethanol), drying methods (hot air‐drying, infrared‐drying, microwave‐drying) and drying temperature on selected characteristics of dietary fibre powder from orange pulp residues were investigated. Pretreatments improved the hydration properties, oil‐holding capacity and glucose dialysis retardation index, but led to losses of fibres, decreased α‐amylase inhibitory activity and aflatoxin B₁ adsorption capacity. Hydration properties, oil‐holding capacity and glucose uptake depended on the structure and porosity of the fibre, while the ability to inhibit α‐amylase and AFB₁ adsorption depended more on the content and molecular fingerprinting of the fibre. Drying condition did not significantly affect functional properties of the fibre, except for the ability to uptake glucose, inhibit α‐amylase and adsorb AFB₁ (P ≤ 0.05). Hot air‐drying at 60 °C resulted in fibre with the highest ability to decrease the rate of glucose and AFB₁ adsorption.     

Effects of washing and membrane removal pretreatments on the antioxidant properties of grass carp (Ctenopharyngodon idella) protein hydrolysates produced by in vitro digestion

The effects of washing and membrane removal pretreatments on the antioxidant properties of grass carp protein hydrolysates prepared through in vitro digestion were investigated. Furthermore, antioxidant hydrolysate was fractionated using ultrafiltration membranes (10, 5, 3 and 1 kDa). Oxygen radical antioxidant capacity (ORAC), DPPH and ABTS‐scavenging activity in a gastrointestinal digest produced from pretreated minced grass carp was increased 1.74‐fold, 1.08‐fold and 1.72‐fold, respectively, compared to untreated minced carp. Compared to the alkaline protease hydrolysate, ORAC, ferric reducing antioxidant power, ABTS‐ and DPPH‐scavenging activity in a gastrointestinal digest prepared from pretreated minced carp were reduced by 11.5%, 60.9%, 16.3% and 78.4%, respectively. The ultrafiltration fraction (<1 kDa) displayed the highest antioxidant activity. The size of molecular weight and the amount of hydrophobic and aromatic residues in hydrolysates played an important role in antioxidant activity. Low‐molecular‐weight fish hydrolysates could serve as a potential source of functional ingredients for promoting health.