Date flesh: Chemical composition and characteristics of the dietary fibre

The date by-products of two date palm (Phoenix dactylifera L.) cultivars, Deglet-Nour and Allig, from the Degach region (Tunisia), were analysed for their main chemical composition. Studies were also conducted on the physicochemical properties (colour, water and oil-holding capacity and rheological behaviour) of dietary fibre (DF) extracted from date flesh. The following values (on a dry matter basis: DM) were obtained for fleshes of Deglet-Nour and Allig cultivars, respectively: sucrose 52.7% and 13.9%, glucose 13.7% and 29.9%, fructose 12.6% and 29.0%, total dietary fibre 14.4% and 18.4%, protein 2.1% and 3%, ash 2.5% and 2.52%. Insoluble DF, the major fraction of total DF, constituted 9.19–11.7% DM for Deglet-Nour and Allig, respectively. The elaboration of DF concentrates from date fleshes was characterised by an extraction yield of 67%. The chemical composition of these DF concentrates showed high total DF contents (between 88% and 92.4% DM) and low protein and ash contents (8.98–9.12% and 2.0–2.1% DM, respectively). The DF concentrates showed a high water-holding capacity (∼15.5 g water/g sample) and oil-holding capacity (∼9.7 g oil/g sample) and pseudoplasticity behaviour of their suspensions. Thus, date DF concentrates may not only be an excellent source of DF but an ingredient for the food industry.     

Chemical composition and dietary fibre of yellow and green commercial soybeans (Glycine max)

Proximate composition and dietary fibre (as non-starch polysaccharides) of yellow soybeans (from conventional, ecological, transgenic and non-transgenic crops) and green soybeans (from conventional and ecological crops) has been studied. Dietary fibre, fat and ash were significantly higher in yellow than in green samples, but moisture and available carbohydrates were significantly lower in yellow soybean than in green ones. Few statistical differences were found for protein between different samples. Soybean seeds were rich in dietary fibre (yellow: 13.7–16.5 g/100 g, green: 9.19–9.45 g/100 g). This component was evaluated as insoluble and soluble fibre, and subsequently, the neutral sugars and uronic acids were determined by gas liquid chromatography and spectrophotometry, respectively. Insoluble fibre became the predominant fibre fraction in yellow and green soybeans (74–78%), and was mainly composed of glucose, uronic acids, galactose, arabinose and xylose. Soluble fibre was between 22% and 26% in both kinds of samples and the principal monomers were uronic acids, galactose and arabinose. The major difference between total dietary fibres of yellow and green commercial samples was the proportion of galactose, which was an important constituent in yellow soybeans (21%) and a minor one in green soybeans (5%).     

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.     

木聚糖酶制取米糠膳食纤维的功能性质

采用木聚糖酶水解米糠膳食纤维,将制备的可溶性膳食纤维(X-SDF)、不溶性膳食纤维(X-IDF)和总膳食纤维(X-TDF)进行分离,研究其功能性质发现,木聚糖酶酶解后,膳食纤维的持水力持油力显著增强,溶胀性降低;阳离子交换能力未见显著变化;X-TDF、X-IDF和X-SDF对葡萄糖的吸附能力分别是RBDF的1.28倍、1.35倍和2.11倍,X-TDF、X-SDF的葡萄糖透析延迟指数相比RBDF显著升高,X-IDF相比RBDF有所降低;在模拟胃和小肠的环境下,X-TDF、X-SDF对胆固醇的吸附量分别为(19.99±1.26)、(23.26±0.52)mg/g和(22.64±1.48)、(27.06±2.22)mg/g,相比RBDF有显著提高。扫描电镜观察其超微结构发现,膳食纤维由不规则块状颗粒组成,木聚糖酶作用后的膳食纤维结构疏松,出现较多空腔和裂缝。     

Acerola and cashew apple as sources of antioxidants and dietary fibre

Several tropical fruits have been described as natural sources of dietary fibre (DF) and phenolic compounds, associated with different health effects. The aim of this work was to ascertain the DF, phenolic compounds content (including non‐extractable polyphenols, mostly associated with DF) and antioxidant capacity in acerola fruits and cashew apples from selected clones. ‘BRS 236’ acerola fruits presented a high antioxidant capacity because of the combination of both extractable polyphenols and l ‐ascorbic acid (providing together a Folin value of 170 kg^?1 g d.m.). ‘CCP 76’ cashew apples contained 28 g kg^?1 d.m. of extractable polyphenols and 13 g kg^?1 d.m. of ascorbic acid as well as a high amount of non‐extractable condensed tannins (52 g kg^?1 d.m.). DF content was of 260 g kg^?1 d.m. in acerola fruit and of 209 g kg^?1 d.m. in cashew apple. Acerola fruits and cashew apple should therefore be considered as new natural sources of DF and phenolic compounds.     

Chemical composition and some properties of modified buffalo milk for infant feeding

A proposed formula for modifying buffalo milk for infant feeding was described. Buffalo milk was diluted with four parts of whey that was produced by addition of citric acid or lemon juice to milk and neutralization with sodium bicarbonate. The chemical composition and the properties of the proposed formula were compared with raw buffalo milk, human milk and buffalo milk modified by the ordinary method. The proposed formula was characterised by low casein/whey protein N comparable to human milk and by curd tension.     

经木聚糖酶处理的玉米皮膳食纤维的组成及其胆盐吸附特性研究

系统地比较了玉米皮膳食纤维(CDF)及其经木聚糖酶酶解后所得产物(XMF)的组成和吸附胆酸盐的特性.通过木聚糖酶的适度降解,XMF在膳食纤维组成、分子量分布及单糖组成上都发生了变化.XMF胆酸盐的吸附能力尤其得到了大幅度的提高,吸附特性也与CDF有所差异.     

Chemical composition and some properties of modified buffalo milk for infant feeding.

A proposed formula for modifying buffalo milk for infant feeding was described. Buffalo milk was diluted with four parts of whey that was produced by addition of citric acid or lemon juice to milk and neutralization with sodium bicarbonate. The chemical composition and the properties of the proposed formula were compared with raw buffalo milk, human milk and buffalo milk modified by the ordinary method. The proposed formula was characterised by low casein/whey protein N comparable to human milk and by curd tension.     

竹纤维的结构及理化性能分析

介绍了竹纤维的化学结构、形态结构和微结构,并对竹纤维的理化性能进行了较为详细的阐述,为竹纤维在纺织领域的应用提供了理论依据。     

Characterisation of alkaline and enzymatic modified insoluble dietary fibre from Undaria pinnatifida

Undaria pinnatifida insoluble dietary fibre (UIDF) was modified by alkali (NaOH solution) and complex enzyme (xylanase and cellulase) to improve the physicochemical properties. Scanning electron microscopy revealed that the surface structure after modification was rough and loose. The characteristic absorption peaks in Fourier transfer infrared spectrometry and X-ray diffraction patterns showed that enzymes can further hydrolyse the UIDF than alkali mainly in amorphous region, and increased the soluble dietary fibre content to 16.31%. The alkaline and complex enzymatic modification both resulted in higher water retention capacity, water swelling capacity, oil absorption capacity, glucose adsorption capacity and the inhibition ability towards α-amylase. The complex enzymatic modification exhibited better features in almost all properties, and the modification did not change the inhibiting mechanism on α-amylase (non-competitive type). Overall, both two modifications could effectively improve the properties of UIDF, which may promote its use in food applications.     

Comparative studies between the optimum dietary fibre sources of some substituted cookies

To realize the line of balance between utilization of dietary fibre sources level of substitution and maximum improvement or minimum reduction of in vitro protein digestibility in high dietary fibre cookies, the optimum level of substitution by corn bran, rice bran and barley husk were studied. Analysis for amino acids composition, infrared absorption spectroscopy and X-ray diffraction were carried out. Rice bran was the best fibre source for improving lysine content. Barley husk fulfilled two criteria viz. improvement in lysine content and minimum decrease in amino acids content.     

Structural characteristics,physicochemical properties and prebiotic potential of modified dietary fibre from the basal part of bamboo shoot

The basal part of bamboo shoot is a novel resource to produce dietary fibre (BDF). However, its insolubility in water, stiff texture and low degradability limit its applicability in foods. This study explored the feasibility of improving the structural and functional properties of BDF by enzymatic hydrolysis and dynamic high-pressure micro-fluidisation (DHPM). Both methods are efficient to reduce the fibre particle size and caused significantly increased roughness on the fibre surface, especially for the porous structure after DHPM treatment. Crystallinity of DHPM-modified fibres was increased from 23.01% to 33.53%, due to the disruption of lignin and hemicellulose, which was further confirmed by the FT-IR spectra. The modified fibres exhibited significantly enhanced swelling capacity and holding water/oil capacities. Moreover, the modified fibres exhibited improved in vitro prebiotic property, which could constantly supply the carbon source and stimulate the growth of Lactobacillus acidophilus ATCC 4356 and Bifidobacterium longum ATCC 15707.     

超微粉碎对脱脂米糠膳食纤维理化特性及组成成分的影响

采用超微粉碎对脱脂米糠膳食纤维进行处理,研究不同粒径的纤维粉体的理化特性及组成成分的变化.实验结果表明,随着超微粉碎程度的加强,粒径的不断减小,膳食纤维的持水力、持油力、膨胀力均有显著提高,而阳离子交换能力先增加后降低;膳食纤维经超微粉碎后,纤维素含量基本保持不变,而部分半纤维素转化为水溶物.     

羽毛纤维的耐化学试剂性能

采用质量损失率和断裂强力、断裂伸长等指标,客观评定常温下羽毛纤维的耐化学试剂性能。实验表明:羽毛纤维具有非常好的耐酸性,在浓度小于150 mL/L的浓H2SO4溶液中,物理性能基本不受影响;其耐碱性能较差,pH值为9的NaOH溶液就会引起羽毛纤维物理性能下降;羽毛纤维对氧化剂非常敏感,0.5 mL/L的NaClO溶液就能明显降低羽毛纤维的断裂伸长和强力;200 mL/L的NaHSO3溶液在空气中不会对羽毛纤维造成明显的损伤。     

Chemical composition,dietary fibre and resistant starch contents of raw and cooked pea,common bean,chickpea and lentil legumes

The chemical composition and the contents of resistant starch and soluble and insoluble dietary fibre of pea (Pisum sativum L.), common bean (Phaseolus vulgaris L.), chickpea (Cicer aretinum L.) and lentil (Lens culinaris Med.) legumes, were studied. Raw and freeze-dried cooked samples were used, both in the form of flour. Protein values of the legumes ranged from 18.5 to 21.9 g/100 g for the raw grains and from 21.3 to 23.7 g/100 g for freeze-dried cooked legumes. Chickpea stood out for the highest lipid content (p < 0.05), the lowest insoluble fibre values, and soluble dietary fibre not detected. The average content of resistant starch found in the legumes did not differ statistically (p > 0.05), being 2.23 ± 0.24 g/100 g for freeze-dried cooked legumes, and showing a slight reduction in comparison to the raw form.     

Ramie fibre: part I. Chemical composition and chemical properties. A critical review of recent developments

The monograph deals with a critical review of the recent research work and development on ramie, a long vegetable bast fibre. The review is divided into two parts. Part I discusses the progress of recent work on ramie, chemical components like fibre degumming, its effects on fibre composition, chemical constituents, i.e. hemicellulose, cellulose, non-cellulosic and mineral matters. Besides various chemical properties of native and modified fibres such as accessibility, infrared, cellulose I-V, DP, grafting, cross linking and resin finishing and dyeing etc. are dealt with.     

Chemical, technological and in vitro antioxidant properties of mango, guava, pineapple and passion fruit dietary fibre concentrate

The aim of this work was to determine the chemical, technological and in vitro antioxidant properties of co-products from the industrialisation of some tropical exotic fruits, such as mango, pineapple, guava and passion fruit, and to evaluate their potential use as dietary fibre sources for food enrichment. Proximate compositions were determined, as well as the total, insoluble and soluble fibre contents. The water holding, oil holding and swelling capacities were also determined. For the antioxidant activity, three different test systems were used (ABTS, DPPH and FRAP). The dietary fibre content of the co-products varied in a range between 69.1 and 81.5g/100g on a dry matter basis with a good balanced ratio between insoluble dietary fibre and soluble dietary fibre. Phenol recovery was dependent on the fruit type and the solvent system used. Methanol:acetone was a more efficient solvent for extracting phenols than ethanol. There was a good correlation between total phenol content and antioxidant capacity of the fruit extracts. All samples analysed had good antioxidant capacity. The results of this study indicate that exotic fruit fibres obtained as co-products in the process to obtain juice may be considered a good source of natural compounds with significant antioxidant activity.     

Mechanisms underlying the cholesterol-lowering properties of soluble dietary fibre polysaccharides

A number of studies have shown a positive relationship between diets rich in soluble dietary fibres (SDF) such as β-glucan, pectin, guar gum and psyllium, and reduced serum cholesterol and thus a decreased risk of cardiovascular disease (CVD). Three major biological mechanisms have been proposed to explain the cholesterol-reducing effects of SDF: prevention of bile salt (BS) re-absorption from the small intestine leading to an excess faecal BS excretion; reduced glycemic response leading to lower insulin stimulation of hepatic cholesterol synthesis; and physiological effects of fermentation products of SDF, mainly propionate. Evidence for the latter mechanism is inconclusive, whereas in vivo, ex vivo and in vitro experiments suggest that BS micelles "bind" to SDF preventing their re-absorption. Whereas, glycemic responses to SDF have been studied extensively, the nature of interactions between bile salt micelles and SDF that lead to incomplete BS re-absorption are poorly defined. Three potential physicochemical mechanisms are proposed together with suggestions for in vitro experiments to test them.     

Chemical composition and physical characteristics of water caltrop during growth

BACKGROUND: The aim of this study was to monitor the chemical composition and physical and morphological characteristics of two varieties of water caltrop during growth in order to determine the optimal harvesting time. RESULTS: The dry matter, starch and amylose contents and α‐amylase activity of fruits of both water caltrop varieties increased during the growth period. Mature fruits contained 142–156 g starch kg^?1 fresh sample and provided 684–697 kcal total energy kg^?1 fresh sample. Dry matter content and bulk density increased significantly from 67 to 207 g kg^?1 and from 0.57 to 1.58 g ml^?1 respectively as growth progressed. Morphological analysis showed that the size and number of starch granules increased as growth progressed. Moreover, both varieties contained substantial amounts of essential amino acids, most of which appeared to be superior to the FAO/WHO reference pattern. CONCLUSION: According to the chemical composition and physical characteristics of water caltrop determined in this study, the optimal harvesting time is 42 days after fruit development. Copyright © 2009 Society of Chemical Industry