Characteristics of fibre‐rich powder and antioxidant activity of pitaya (Hylocereus undatus) peels

The contents of total dietary fibre (TDF), soluble dietary fibre (SDF), insoluble dietary fibre (IDF) and functional properties of fibre‐rich powders (FRP) from pitaya peels with different particle size (FRP80, FRP140 and FRP250) were determined. Results showed that FRP140 had higher TDF (79.37%) and SDF (33.07%) with a balanced ratio of SDF/IDF (1:1.32) and higher water‐holding capacity (54.20 g g^?1), swelling capacity (50.63 mL g^?1), oil‐holding capacity (2.65 g g^?1) and glucose dialysis retardation index (62.83% at 60 min), compared with FRP80 and FRP250. Therefore, physiochemical properties of FRP140 were further investigated. SDF of FRP140 mainly contained rhamnose (4.95%) and galactose (1.98%), with 9.45% galacturonic acid, while IDF dominantly contained xylose (4.76%) and galactose (3.42%), with 18.54% klason lignin. Total phenolic content was 7.75 mg g^?1 and mainly composed of salicylic acid (0.98 mg g^?1) and protocatechuic acid (0.45 mg g^?1). Furthermore, FRP140 showed significant reducing power, DPPH‐scavenging activity and nitrite‐scavenging ability.     

Structure and properties of sugar beet fibres

Fibrous fractions were prepared from sugar beet pulp (RF) by sequential extractions with potassium oxalate, 0.05 M hydrochloric acid at 85°C and 0.05 m sodium hydroxide at 4°C. The overall composition, polysaccharide structure and some physico-chemical properties (cation exchange capacity, CEC; water holding capacity, WHC; swelling) of each fraction were determined. RF was mostly composed of carbohydrates (66.3 %) with minor amounts of ash, proteins and lignin. The main polysaccharides were highly methylated and acetylated pectins, cellulose and arabinans. The oxalate residue (82.1 % of RF) exhibited only minute differences from RF whereas the acidic and alkaline residues, accounting for 42.8 % and 35.5 % of RF, respectively, were enriched in cellulose and hemicelluloses (xylans, xyloglucans, mannans) and mostly devoid of pectins and arabinans. CEC and WHC of fractions were closely related to the content of unmethylated galacturonic acid residues. The influence of the ionic form of ionisable groups was demonstrated, the Na⁺ form giving the highest WHC. The ionic strength of the medium can reduce the WHC, especially in the case of the acid and alkali-extracted fibres.     

Water‐holding capacity of insoluble fibre decreases free water and elevates digesta viscosity in the rat

BACKGROUND: The relationships between possible physiological properties of insoluble fibre and the viscosity of digesta are poorly understood. The aim of this study was to investigate the effect of insoluble fibres with different water‐holding capacity, swelling, oil‐holding capacity and cation exchange capacity on gastric, small intestinal and caecal contents in rats fed a semi‐purified diet containing either no fibre (control), 50 g kg^?1 tossa jute fibre or 50 g kg^?1 shiitake fibre. RESULTS: The water‐holding capacity, swelling, oil‐holding capacity and cation exchange capacity of insoluble fibres of tossa jute were higher than those of shiitake (P < 0.001). The order of the viscosities of digesta was control group < shiitake fibre group < tossa jute fibre group in gastric, small intestinal and caecal contents (P < 0.05). The digesta viscosity at a shear rate of 40 s^?1 was strongly correlated with the free water content of digesta (r = ? 0.89; P < 0.01). The free water content of digesta depended on the water‐holding capacity of insoluble fibres represented as a linear function with negative slope (P < 0.001). CONCLUSION: The viscosity of digesta depends on the free water content, and this is reduced by fibre that holds water and can swell. Copyright © 2008 Society of Chemical Industry     

An investigation into the physical properties of fibre prepared from several carrot varieties at different stages of development

Important physical properties of dietary fibre include water holding capacity (WHC) and cation exchange capacity (CEC). In this investigation fibre prepared from different varieties of the same species, the carrot Daucus carota, have been sampled at different stages of development to determine whether these physical properties were dependent upon variety and the age of the plant. Results for WHC (g g^?1 fibre) were dependent on the method of analysis. Differences found between varieties for WHC measured by centrifugation (mean 23.7 g, range 13.4–32.3) were not apparent when measured by filtration of a corresponding sample (mean 27.9 g, range 17.2–45.5). Differences between methods probably reflect structural differences in the fibre influenced by age and variety. Both methods showed carrot fibre to have a relatively high WHC. The CEC (meq g^?1 fibre) was found to be similar between varieties but to increase with age within each variety, (mean 1.44 meq, range 1.07–2.42). The type of exchange did not change and the CEC 100 g^?1 fresh carrot remained constant between varieties and also within each variety. The pK determined for each sample was between 4.42–5.30 which suggests pectins to be responsible for the CEC.     

Preparation and properties of a white protein fraction in high yield from sugar beet (Beta vulgaris L) leaves

Chlorophyll-free protein has been recovered at a yield in excess of 50 % from sugar beet (Beta vulgaris L) leaf juice after two successive pH treatments. This corresponds to about 60 kg of white protein per hectare. The main component of the final preparation is ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39). Compared with the unfractionated protein from leaf extracts, the white protein preparation has higher contents of tyrosine, threonine, glutamic acid and proline and lower ones of isoleucine, lysine (although still high: 76mg g^?1) and glycine. The content of methionine is high (24mg g^?1) probably as a result of the addition of sulphite during protein extraction. The white protein preparation has a low level of ether extractives (17mg g^?1) and a moderate ash (52mg g^?1) content. The white protein is rapidly degraded by pepsin, trypsin and pancreatic juice.     

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.     

Sucrose accumulation and osmotic potentials in sugar beet at increasing levels of potassium nutrition

In a pot experiment sugar beet Beta vulgaris L. ssp. vulgaris, cv. Kawetina, was grown on alluvial soil (21 mg exchangeable K 100 g^?1) containing 0 (K₁), 20 (K₂), 40 (K₃) and 60mg fertiliser K 100 g^?1 soil (K₄). The plants were sown on 15 March 1983 and harvested on 23 June, 14 July and 30 August 1983. At final harvest root dry weight/plant had reached 269 g in K₁ and between 304 and 310 g in K₂-K₄. Sucrose values were 15% (K₁) and 17.3–17.7% of root fresh weight (K₂-K₄) respectively. The osmotic potential of the storage root decreased with increasing K nutrition and time. At final harvest ψ, was between ?1.83 (K₁) and ?2.26 MPa (K₄), 75–79% thereof being contributed by sucrose. Sucrose concentrations in press sap increased from 340–400 mM on 23 June to 475 (K₁) and 540–570 mM (K₂-K₄) at the end of August. In the same period K concentrations declined from 40–100 to 10–35 mM K⁺. The sucrose, K and Mg concentrations measured in the press sap were lower than those calculated from sucrose, K, Mg and moisture content of the storage root. This indicates that press sap from thawed storage root tissue is not fully representative. Betaine, analysed only at final harvest, significantly increased with increasing K concentrations in the storage root (r=0.83) and a significant linear regression was found between betaine and sucrose accumulation (r=0.57). This is consistent with the role of betaine as a cytosolic osmoticum for sugar beet storage tissue. Other solutes in the cytosol may also contribute to osmoregulation as sucrose accumulates in the vacuoles.     

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.     

Seasonal Changes in the Composition and Properties of a High Dietary Fibre Powder from Grapefruit Peel

Seasonal changes in composition and properties of a high dietary fibre product from grapefruit peel were studied. Total dietary fibre decreased in January as compared to September (586–686 g kg^-1). Main constituents from soluble fibre were: uronic acids (172–233 g kg^-1), arabinose (13–41 g kg^-1), galactose (4–11 g kg^-1), glucose (5–10 g kg^-1) and xylose (2–3 g kg^-1). Insoluble dietary fibre (385–392 g kg^-1) did not significantly change during the season. Its main constituents were: Klason lignin (29–37 g kg^-1), uronic acids (33–70 g kg^-1) and neutral sugars: glucose (149–196 g kg^-1), mannose (45–50 g kg^-1), xylose (25–38 g kg^-1), galactose (20–22 g kg^-1) and arabinose (16–45 g kg^-1). Total neutral sugars from dietary fibre decreased over the harvest period (315–383 g kg^-1) and an inverse trend was observed in total free-sugars from samples (49–85 g kg^-1). Both, water holding capacity (7·0–9·3 g water g^-1 dry sample) and glucose retardation index (7·0–25·3%) decreased from early stages in fruit development until late in the harvest season. Seasonal changes in grapefruit peel should be taken into account, in order to standardise the quality of rich fibre products. © 1997 SCI     

Effect of dietary fibre and MTGase on the quality of mackerel surimi gels

BACKGROUND: The effects of microbial transglutaminase (MTGase; 5 g kg^?1) and dietary fibre (inner pea fibre and chicory root inulin, 20 and 40 g kg^?1) on gels from surimi made with Atlantic (Scomber scombrus) and chub mackerel (Scomber japonicus) were studied with the purpose of achieving a better understanding of the underlying phenomena and improving gels. RESULTS: MTGase addition improved textural properties (namely, cohesiveness increased from 0.19–0.41 to 0.59–0.72) and increased pH and water‐holding capacity (WHC). Moreover, MTGase reduced the elastic and viscous modules and darkened gels; protein solubility declined, meaning greater protein aggregation, according to electropherograms. MTGase had no unequivocal effect upon the gels' microstructure. Pea fibre increased hardness (an increase of almost 60% with 40 g kg^?1) and related parameters, the elastic and viscous modules and WHC. Pea fibre reduced extractable protein in sodium dodecyl sulfate and urea (in the absence of MTGase) as well. Scanning electron microscopy revealed different structures for gels containing pea fibre. Regarding inulin, it worsened textural quality and WHC. CONCLUSION: A combination of MTGase and pea fibre can improve a poor quality surimi. Copyright © 2009 Society of Chemical Industry     

Comparative Analysis of Betalain Content in Stenocereus Stellatus Fruits and Other Cactus Fruits Using Principal Component Analysis

Stenocereus stellatus fruits from Puebla, Mexico, with red, purple, yellow, and white pulp were characterized regarding their total betalain content, and physicochemical properties. The total betalain content was 856.07–2968 µg per gram of pulp dry weight. Using principal component analysis, the levels of pigments in S. stellatus fruits were compared with 32 samples from other cactus fruits. As a result, three confidence intervals for total betalain content (μg g^?1) were calculated: low (<1208), medium (2935–3288), and high (4488–9248). Thus, the cactus fruits can be categorized as a poor, good, and excellent source of betalain pigments.     

从甜菜粕中提取食用纤维和果胶的研究

甜菜废粕是量大而集中的甜菜制糖废弃物，由它制成的食用纤维具有高的持水性，有明显的降血脂、降胆固醇、降血糖作用，能大幅度降低膳食热量，是目前性能最好的食用纤维之一。本文介绍了甜菜食用纤维的提取工艺，性能测试，在保健食品中的应用及卫生毒理和临床研究结果。还研究了从甜菜粕中提取果胶的工艺（包括一种不使用酒精的果胶提取工艺）。     

Antioxidant properties of various solvent extracts of potato peel,sugar beet pulp and sesame cake

BACKGROUND: Growing interest in the replacement of synthetic food antioxidants by natural ones has fostered research on vegetable sources and screening of raw materials to identify new antioxidants. The food‐processing industry generates substantial quantities of phenolic‐rich by‐products that could be valuable natural sources of antioxidants. In this study the antioxidant properties and total phenolic, flavonoid and flavonol contents of three industrial by‐products, sugar beet pulp, sesame cake and potato peel, extracted with various solvents were examined. Since different antioxidant compounds have different mechanisms of action, several methods were used to assess the antioxidant efficacy of extracts. RESULTS: Among the six solvents tested, methanol gave the highest extract yield of potato peel and sugar beet pulp, while diethyl ether gave the highest extract yield of sesame cake. Methanol exhibited the highest extraction ability for phenolic compounds, with total phenolics amounting to 2.91, 1.79 and 0.81 mg gallic acid equivalent g^?1 dry weight in potato peel, sugar beet pulp and sesame cake extracts respectively, and also showed the strongest antioxidant capacity in the three assays used. All three methods proved that potato peel extract had the highest antioxidant activity owing to its high content of phenolic compounds and flavonoids. CONCLUSION: On the basis of the results obtained, potato peel, sugar beet pulp and sesame cake extracts could serve as natural antioxidants owing to their significant antioxidant activity. Therefore they could be used as preservative ingredients in the food and/or pharmaceutical industries. Copyright © 2009 Society of Chemical Industry     

The Enhancement of Polygalacturonase and Polymethylgalacturonase Production on Solid-State Conditions by Aspergillus foetidus

In this study, a previously isolated strain of Aspergillus foetidu s Ege-K-635 producing highly active polygalacturonase and polymethylgalacturonase was used for improvement of enzyme production using solid-state conditions. To enhance the enzyme yield, the mixture of two substrates such as sugar beet pulp and wheat bran, having different ratios of carbon-nitrogen and moisture levels was used. Further the effect of the amount of inoculum was investigated. Physical parameters for the highest polygalacturonase and polymethylgalacturonase production under solid state conditions were determined on wheat bran: the sugar beet pulp (1:2) mixture substrate composition having a 31:1 carbon-nitrogen ratio with 8 × 10⁶ spores/gram of dry substrate as the inoculum amount. Adequate moisture levels were 75% and 70% for polygalacturonase and polymethylgalacturonase, respectively. Under these conditions, the highest activities obtained were 385 ± 12.3 Ug^?1 on the third day for polygalacturonase and 18.3 ± 3.2 Ug^?1 on the second day for polymethylgalacturonase.     

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.     

Antioxidant activity and phenolic content of lentils (Lens culinaris), chickpeas (Cicer arietinum L.), peas (Pisum sativum L.) and soybeans (Glycine max), and their quantitative changes during processing

Total phenolic content (PC) was ～12 mg g^?1 in lentils, 2.2 mg g^?1 in chickpeas, 2.3 mg g^?1 in soybeans, 2.5 mg g^?1 in yellow peas and 1.2 mg g^?1 in green peas. Total antioxidant activity (AA) determined by ABTS (2,2′‐azinobis‐3‐ethyl‐benzthiazoline‐6‐sulfonic acid) assay was highest in lentils at around 14 μmol Trolox equivalent antioxidant capacity (TEAC) g^?1 and lowest in green peas at 1.9 μmol TEAC g^?1. Bound phytochemicals contributed to 82–85% total AA in lentils. Free phytochemicals contributed more to total AA in chickpeas, yellow peas, green peas and soybeans than bound phytochemicals. AA and PC was reduced by ～80% in lentils and <30% in yellow peas by decortication, by 16–41% in lentils, chickpeas and peas by cooking, and by 22–42% in lentils by soaking. Total AA was significantly correlated with total PC. Soybeans had the greatest ability to scavenge free radicals, inhibit lipid peroxidation and chelate metals among the legumes tested. Different legumes exhibited different AA mechanisms.     

Effect of pretreatments and drying temperatures on sweet potato flour

Effect of pretreatments with 1 w/v% sodium hydrogen sulphite (NaHSO₃) and 1 w/v% calcium chloride (CaCl₂) and drying temperatures (55, 60 and 65 °C) on sweet potato flour were investigated. Flour treated with CaCl₂ had higher amounts of ascorbic acid and β‐carotene (10.61–12.54 and 3.26–3.46 mg 100 g^?1 wet basis, respectively) than that treated with NaHSO₃ (9.47–11.47 and 3.05–3.43 mg 100 g^?1 wet basis, respectively). Total phenolic content and water absorption index (wet basis) were highest at 65 °C when treated with NaHSO₃ (10.44 mg 100 g^?1 and 2.49 g g^?1 respectively) and CaCl₂ (9.52 mg 100 g^?1 and 2.85 g g^?1 respectively). Swelling capacity (wet basis) was highest at 60 °C when treated with CaCl₂ (2.96 g g^?1) whereas when treated with NaHSO₃ (2.85 g g^?1) it was highest at 55 °C. Freeze‐dried samples treated with NaHSO₃ had higher lightness and total phenolic content while CaCl₂‐treated samples had higher β‐carotene and ascorbic acid. The results showed that good quality flour could be produced after soaking in CaCl₂ and dried at 65 °C.     

Degradation and physicochemical changes of barley and pea fibre along the gastrointestinal tract of pigs

The degradation of barley and pea fibres along the gastrointestinal tract (GIT) of pigs and its relation to changes in some of their physicochemical properties were investigated. Ileal and caecal digesta containing pea cotyledon fibre showed the highest (P < 0.05) swelling (33.1–36.7 ml g^?1 DM) and water retention capacity measured by centrifugation (17.9–21.2 g g^?1 DM) and by osmotic pressure (9.0–9.1 g g^?1 DM). The particle size of barley hull did not change along the GIT (160–207 µm), whereas that of pea cotyledon and pea hull was drastically reduced in faeces (62–65 µm) compared with the ileum and caecum (198–415 µm). The digestibility of non‐starch polysaccharides (NSP) was lowest for barley hull in the ileum (5% of intake), caecum (0% of intake) and faeces (26% of intake). The digestibility of NSP was highest for pea cotyledon fibre and dehulled barley in the proximal hindgut and for pea cotyledon fibre in faeces (96% of intake for pea cotyledon vs 74–82% of intake for dehulled barley and pea hull). In conclusion, hydration properties and particle size add valuable information when describing the fermentation of fibres in the GIT. However, they cannot be used alone as indicators of the extent of fermentation of different fibres. The results also suggested that the fibre source and the organisation and lignification of the cell walls lead to different fermentation processes along the GIT of pigs. © 2001 Society of Chemical Industry     

Physical and chemical properties of chufa (Cyperus esculentus L) tubers grown in the Çukurova region of Turkey

Four lines of chufa (Cyperus esculentus) grown in 1998 and 1999 in the Çukurova region of Turkey were analysed for their physical properties, proximate chemical composition and fatty acid contents. The chufa lines contained on average (g kg^?1) 932.8 dry matter, 245.0 crude lipid, 256.8 starch, 14.3 ash, 50.5 protein, 89.1 crude fibre, 17.1 reducing sugar, 154.3 total sugar and 130.4 sucrose. Hunter L, a⁺ and b⁺ colour values of ground chufa samples were in the ranges 55.93–60.59, 3.71–5.09 and 15.60–16.85 respectively. Individual chufa tubers weighed between 0.224 and 0.283 g. The fatty acid composition of chufa oil included (g kg^?1) 689.2–732.9 oleic acid, 125.5–141.2 palmitic acid and 99.6–154.6 linoleic acid, which is comparable with that of olive oil. After storage for 1 year the differences in mean values were significant (p < 0.05). © 2002 Society of Chemical Industry     

The amylose and lipid contents,dimensions, and gelatinisation characteristics of some wheat starches and their A- and B-granule fractions

Starches isolated from 23 bread wheats (Triticum aestivum) and 26 durum wheats (T. durum) contained 26.3-30.6% (mean 29.1%) total amylose, 19.3–25.1% (mean 22.9%) apparent amylose and 783–1144mg 100g^?1 (mean 977 mg 100g^?1) lysophos-pholipids. Gelatinisation temperatures were 57.3–64.9°C (mean 61.8°C) and enthalpies 6.4–11.8 Jg^?1 (mean 9.7Jg^?1) in excess water, measured by differential scanning calorimetry. There were no correlations between any of these parameters. Starch granule size distributions were determined with a Coulter Counter and 100–channel analyser. A-granule mean volumes were 1235–2585μm³ (av. 1778), modal volumes 863–1804μm³ (av. 1264), mean diameters 13.9–16.0μm (av. 13.99), and specific surface areas 0.236–0.302m²g^?1. B-granule mean volumes were 35.4–100.4μm³ (av. 55.9), modal volumes 16.5–54.5μm³ (av. 27.7), mean diameters 3.66–5.07μm (av. 4.09), and specific surface areas 0.684–0.920m²g^?1. The B-granule contents of the starches were 12.8–34.6% (av. 27.3) by weight (sedimentation method) and 13.0–37.3% (av. 24.0) by volume (Coulter method), the latter being the more accurate method.