Effects of dietary fiber on some indices of the activity of the gastrointestinal tract in rats]

Now nobody doubts of necessity and importance of inclusion of vegetative food fibres (as the separately isolated biopolymers--lignin, cellulose, gemicellulose, pectine substances; in composition of a food fibres complex or introduction last in traditional products of nutrition) in a daily human diet. Is proved by experimental researches, that the investigated kinds of food fibres are non-toxic, do not influence on internal structure, are well perceived by animals and can be recommended as the additive in a human diet.     

Gravimetric method for the determination of insoluble and soluble dietary fibres

The present paper describes a simple method for the determination of the insoluble and soluble dietary fibres in food. In a first step, starch and proteins are removed by enzyme treatment. The insoluble dietary fibres are determined gravimetrically after centrifugation and washing of the residue with water, ethanol, acetone and diethyl ether. The water-soluble dietary fibres are recovered from the supernatant liquid of the centrifugation by dialysis, freeze-drying, and subsequent weighing. The method has been used for the determination of dietary fibres in by-products from the industry.     

Physico-chemical properties of commercial fibres from different sources: A comparative approach

The lower intake of fibre and fibre-containing foods has refocused the food industry on the benefits of incorporating different fibres in the foodstuff. Nowadays, a whole range of fibres are available in the market, but sometimes a good choice becomes complicated due to their varied physico-chemical properties. In order to give some light when selecting fibres, a comparative study regarding some physical properties of commercial fibres from different sources is presented, with a view to increasing their use in food products, namely bakery products. Commercial fibres included in this study were hydroxypropylmethylcellulose, cellulose, locust bean gum, guar gum, inulin, galactooligosaccharides, oat and wheat fibres, and fibres extracted from apple and bamboo. Particle size distribution (PSD) of the dry commercial fibres ranged from around 10 to 334 μm; moreover PSD in wet (water and ethanol) form was also determined to have precise information about their behaviour when processing. Cereal fibres (oat 600 and wheat) exhibited the highest values for hydration properties (swelling, water holding and water binding capacity). Only the hydrocolloids (HPMC, locust bean gum and guar gum), with the exception of cellulose, yielded highly viscous solutions during the heating-cooling cycle; moreover oat 600 and apple fibre developed viscous solutions after cooling. HPMC, locust bean gum and guar gum significantly augmented the four SRC values, thus those hydrocolloids affected the relative contributions to water absorption of proteins, carbohydrates, damaged starch and pentosans. Fibre sources and degree of replacement significantly affected the SRC values for the four solvents in all the fibre groups, with the exception of lactic acid SRC in the case of cereal fibres. Differences in fibres effect on wheat flour quality can be easily detected by assessing solvent retention capacity, which can give information on the end use functionality of the wheat flour.     

The use of non‐food crops in the UK construction industry

The use of non‐food crops in construction has a long history. In addition to the use of wood as a mainstay in building housing, until recently the uses were limited to the inclusion of fibres such as wool in plasters and renders, the use of straw in ‘wattle and daub’ walling and, of course, the use of reed and straw in thatching. During the last 15 years the move toward sustainable buildings has led to a renewed interest in the use of non‐food crops, particularly straw bale construction, the use of fibres in walls and boards and the development of insulation products from wool. This review covers the development of these materials in the UK as well as looking at the demand for more traditional uses such as thatch. Copyright © 2006 Society of Chemical Industry     

Comparison of effects of prickly pear (Opuntia ficus indica sp) fruit,arabic gum,carrageenan, alginic acid,locust bean gum and citrus pectin on viscosity and in vitro digestibility of casein

The consumption of high levels of fibres can induce a decrease in both food digestibility and nutrient availability. Prickly pear is a pectin‐rich fruit and it is possible to use it to decrease plasma cholesterol levels. Its effect on food digestibility deserves attention. This effect was determined by using a mixture of a constant quantity of casein and an increasing quantity (10, 20, 25% of the casein) of prickly pear pulp, skin and seed. In parallel, the effect of similar mixtures of carrageenan, gum arabic, locust bean gum, alginic acid and citrus pectin with casein was also studied. The flow behaviour of the different mixtures was determined and their digestibilities were measured using an in vitro digestion cell device. The apparent viscosities of the mixtures with prickly pear components and gum arabic were similar. The nature and level of fibres in the diet modified nitrogen release in the in vitro digestion cell model. The pulp of the prickly pear decreased the digestibility of the casein‐based diet to a greater extent than the other soluble fibres, whatever the percentage used. The results suggest that the decrease in N release in the digestion cell model is due to the interaction of the fibres with the enzymes or casein rather than to the apparent viscosity of the mixtures. © 2000 Society of Chemical Industry     

Analysis of dietary fibre.

An analytical procedure for the determination of dietary fibre in food is described. The method consists of an enzymic in vitro digestion with pepsin, pancreatin arid glucoamylase. Insoluble fibres are recovered by centrifuging and soluble fibres by precipitation with ethanol. The method has been applied to 19 cereal fibres, vegetables and fruits and compared to the neutral and acid detergent methods. The soluble fibres accounted for 4–60% of the total dietary fibre. The component sugars and uronic acids of several fibre fractions have been quantitatively determined. The mild biochemical treatment of the samples makes it possible to study further physical properties of dietary fibres important for their physiological action.     

Dietary fibre, glycaemic response, and diabetes

The much publicised global trend in rising levels of obesity and diabetes has refuelled interest in the dietary intake of the macronutrients (fat, protein, and carbohydrates) necessary to maintain the state of normalcy (good health) of an individual. Both scientific and public attention have focused on the dietary mediation of chronic health syndromes, either through use of dietary supplements, or a review of the whole diet situation. Dietary supplements have been used extensively both as pharmacological supplements, food ingredients, in processed foods to aid weight control, and the regulation of glucose control for diabetic patients. Particular interest has focused on the use of dietary fibres, especially soluble dietary fibres (such as guar gum, locust bean gum, and psyllium fibres), resistant starch, and slowly digestible carbohydrates. These have been shown to alter food structure, texture, and viscosity, and hence the rate of starch degradation during digestion. Research has also illustrated an association between the rate of carbohydrate degradation during digestion, and the regulation of postprandial blood sugar and insulin levels. The current paper explores the potential use of dietary fibres in the treatment of obesity and diabetes.     

Fruit‐based functional foods I: production of food‐grade apple fibre ingredients

With the increased consumer interest in fibre‐enriched functional foods, industrial‐scale methods for functional fibre production are demanded. The development of a food‐grade fibre preparation method at lab scale that is feasible for industrial scale‐up is a pre‐requisite. This paper describes two lab‐scale fibre preparation methods that have potential to be scaled up to industrial setting for the production of fruit fibres containing desired bioactives and functionality. The two methods, one aqueous and the other ethanolic, were used to isolate fibres from Granny Smith apples (Malus domestica Borkh cv. ‘Granny Smith’). In the aqueous method, ground apple tissues were suspended in HEPES buffer (20 mM, pH 6.5), and then mechanically ruptured using an Ultra‐Turrax and ring grinder. Between steps, the cell‐wall materials were washed with the HEPES buffer. In the ethanolic method, ground apple tissues were stirred in 72% ethanol at 4 °C, filtered, re‐suspended in 72% ethanol and then washed. Microscopic examination and chemical analysis were performed on the resultant fibres. The aqueous method produced natural and uniform dietary fibres in the form of plant cell walls containing 0.282 g uronic acid per g dried fibre. By comparisons, the ethanolic method produced crude fibres containing only 0.182 g uronic acid per g dried fibre, the lower uronic acid content indicating the presence of impurities. Thus, the aqueous method appeared to be advantageous in terms of the retained pectic polysaccharide content and cost‐effectness for industrial scale‐up. Further characterisation using Folin‐Ciocalteu assay and high performance liquid chromatography indicates that the fibres obtained by the aqueous method contained significant amounts of phenolic compounds (2.6 mg catechin equivalent per g dried fibre). These results suggest that fibres obtained by the aqueous method may be more suitable for functional food applications where fibres with high pectic polysaccharide and beneficial phenolic antioxidants are preferred.     

The effect of a diet enriched with food fibers and polyunsaturated fatty acids on the composition of the lipid components in the enterohepatic circulation system in rabbits with cholestasis

In experiments on rabbits that had undergone partial constriction of the choledochus, the development of calculous hepatocholecystitis was observed in a half of the operated on animals. No biliary calculi were detected in the animals that received the ration enriched with food vegetable fibres, beta-sitosterol and linoleic polyunsaturated fatty acids after similar operations.     

Mixing properties of fibre-enriched wheat bread doughs: A response surface methodology study

Fibre-enriched baked goods have increasingly become a convenient carrier for dietary fibre. However, the detrimental effect of fibres on dough rheology and bread quality continuously encourages food technologists to look for new fibres. The effect of several fibres (Fibruline, Fibrex, Exafine and Swelite) from different sources (chicory roots, sugar beet and pea) on dough mixing properties when added singly or in combination has been investigated by applying a response surface methodology to a Draper-Lin small composite design of fibre-enriched wheat dough samples. Major effects were induced on water absorption by Fibrex that led to a significant increase of this parameter, accompanied by a softening effect on the dough, more noticeable when an excess of mixing was applied. Conversely, Exafine increased water absorption without affecting the consistency and stability of dough, which even improved when combined with Swelite. Fibruline showed little effect on dough mixing parameters, but showed synergistic effects with pea fibres. The overall result indicates that the use of an optimised combination of fibres in the formulation of fibre-enriched dough allow improving dough functionality during processing.     

Red mold dioscorea decreases blood pressure when administered alone or with amlodipine and is a potentially safe functional food in SHR and WKY rats

Hypertension is a risk factor for metabolic syndromes and cardiovascular diseases. Statins are antihypertensive, but can cause rhabdomyolysis as a side effect, which involves the breakdown of muscle fibres and release of myoglobin into the bloodstream. In this study, we used hypertensive rats to investigate whether the interaction between Monascus-fermented products (red mold dioscorea; RMD) and amlodipine increases the risk of rhabdomyolysis and toxicity. A single oral dose of RMD (176 mg/kg) significantly decreased systolic blood pressure (SBP) and diastolic blood pressure (DBP). Moreover, administration of RMD, alone or in combination with amlodipine, did not cause significant rhabdomyolysis and did not impair the metabolic or physiological functions of the liver or kidney. RMD treatment had hypocholesterolemic and hypotriacylglycerolemic effects, indicating that RMD may prevent the incidence of atherosclerosis. The findings of this study lend support to the potential use of RMD as a novel therapeutic and antihypertensive functional food.     

Effect of fructose-containing beverages on glycemic parameters in patients with type II diabetes mellitus

The dynamics of glycemia after meal in 21 patients with type II diabetes under the influence of drinks with fructose or sugar and enriched with soluble fibres was investigated. To estimate glycemia after meal in first stage of investigation the test-meals with 50 g carbohydrates (cocktails of juices "Multivitamin" with fructose and sugar, or bread) were used. In second stage, carbohydrates "Peach nectar with fructose" and cocktail of juices "Multivitamin with fructose" were used. The level of glucose in capillary blood was defined after 14-h fasting and 30, 60, 120 and 180 minutes after every test-meal. "Peach nectar with fructose" enriched with fructose and soluble food fibres (pectin) caused glycemic response in a less degree.     

人造牛肉的研究

将植物制成蛋白纤维,生产色、香、味、质地及口感均酷似天然肉品的研究在国外已取得重大进展,产品已广泛应用于学校、医院、监狱等的食堂中。我国在这方面的研究则刚兴起,本文根据天然牛肉纤维较粗的这一特点,应用“粗纺法”直接将大豆分离蛋白纺成1mm左右的纤维,以此为原料生产人造牛肉,并对该法存在的问题及解决途径作了探讨。     

Controlled release of thymol from zein based film

Active packaging materials, able to release antimicrobial compounds into foodstuffs, can be used in order to inhibit or slow down bacterial growth during storage. Zein-based mono and multilayer films were loaded with spelt bran and thymol (35% w/w) to obtain edible composite polymeric materials. Various composite systems were developed to control the release of thymol. In particular, the thickness of the layers and the biodegradable fibres amount were varied. Results highlight that thymol release rate decreased with the increase of the film thickness for both mono and multilayer films, without spelt bran addition. Conversely, a significant increase of thymol release rate with the increase of the bran concentration is recorded for both mono and multilayer films.Industrial relevanceIn recent years, food safety is an important area of concern to the food industry. This fact requires packaging to be an integral part of the preservation concept. Consequently additional antimicrobial activity from the packaging material can aid in shelf life extension. The present work is focused on the development of controlled release systems based on zein incorporated with an active compound, thymol and natural fibres. Release rate of thymol from the developed mono and multilayer films, as affected by layers thickness and fibres amount, was evaluated.     

Esterification of insoluble fibres using high-pressure homogenisation and their potential vitamin carrying and releasing abilities

The esterification of carambola (starfruit) insoluble fibre (IF) and cellulose using high-pressure homogenisation without chemical catalyst was carried out as well as the evaluation of vitamin carrying and releasing abilities of the esterified fibres. Fourier transform infrared spectroscopic analyses showed that these fibres underwent structural changes and were esterified with lactic acid via a simple and fast process of high-pressure homogenisation. In vitro studies showed that the esterified fibres were capable of carrying vitamin E (∼11.2 mg g⁻¹ composite) and releasing nutrient slowly. In vivo studies further demonstrated that feeding the esterified carambola IF-vitamin composite could help maintain plasma vitamin E at relatively higher concentrations (∼1.7- to 3.8-fold of the initial value) for better utilisation for at least 5 h. The results suggested that the esterified insoluble fibres, especially the esterified carambola IF, could be exploited as potential nutrient carriers in functional food applications and slow-release formulations.     

Edible mushrooms’ enrichment in food and feed: A mini review

Dietary fibres and high fibre-containing foods have been a huge attraction among researchers and nutraceutical industries due to their health-promoting benefits. From Greek and Roman times, edible mushrooms are considered the ‘elixir of life’ and are often stated as a new source of dietary fibre. Containing rich sources of essential amino acids and polysaccharides, mushrooms are viewed as an advantage over protein sources of both animal and plant origin. Additionally, the ability of mushrooms to grow under controlled conditions and attain high yield in a short span has made this added-value food of extreme interest. Nowadays, mushrooms and their by-products have been used to fortify various food products as well as for use in animal feed owing to their bioactive, therapeutic and nutritional value. Hence, this review intends to highlight the current knowledge on edible mushrooms and their waste for food and feed enrichment and nutritional purposes, along with their role in human and animal diet.     

Encapsulation of food grade antioxidant in natural biopolymer by electrospinning technique: A physicochemical study based on zein–gallic acid system

Gallic acid was successfully incorporated into zein ultra-fine fibres at different loading amount (5%, 10% and 20%) in order to develop an encapsulating technology for functional ingredient delivery using electrospinning. The produced fibres exhibit diameters ranging from 327 to 387 nm. The physical and thermal properties of encapsulated gallic acid were determined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC); and the interaction between gallic acid and zein was attested by attenuated total reflection-Fourier transform infrared (ATR-FTIR). Thermogravimetric analysis (TGA) demonstrated a different thermal stability of the fabricated complex before and after the gallic acid incorporation. Lastly, the 1,1′-diphenyl-2-picrylhydrazyl (DPPH) assay showed that the gallic acid had retained its antioxidant activity after incorporation in zein electrospun fibres. Overall, electrospinning technique had shown promising results as an efficient and effective method for the preparation of sub-micron structured encapsulated functional ingredient that may find uses in food industry.     

Alternative extraction techniques for analysis of acrylamide in food: Influence of pH and digestive enzymes

Acrylamide in food is normally measured as “water-soluble free acrylamide”. However, it is shown that the technique of extraction, according to the method for extraction of dietary fibres or at high pH can affect the results. This has to be accounted for, particularly in the assessment of exposure and in studies of bioavailability and, in the long term, health risk assessment.     

Micronised-roasted coffee from unripe fruits improves bioactive compounds and fibre contents in rice extruded breakfast cereals

Unripe green coffee is one of the by-products from coffee processing that does not have many applications in higher value-added food products. This study aimed to evaluate the chemical, technological, and sensory properties of rice-based breakfast cereal made with micronised-roasted coffee (MRC) from green coffee fruits. The products were elaborated with different MRC concentrations (2, 5 and 9%) and manufactured in a single screw extruder. Data were analysed by analysis of variance and Tukey's test (p < 0.05). The increase in MRC concentration improved the contents of caffeine, chlorogenic and caffeic acids in the breakfast cereals, and reduced the luminosity and expansion index due to the presence of brown colour and fibres from coffee beans. The cereal made with 5% of MRC was more accepted by consumers. Thus, MRC has proven to be a potential source of bioactive compounds, fibres and natural brownish colour for breakfast cereals.     

Applying ultrasound-assisted processing to obtain cellulose fibres from rice straw to be used as reinforcing agents

Rice straw (RS) is one of the most globally abundant agro-industrial residues. For its valorisation, a green combined ultrasound-reflux heating method was applied to obtain cellulose fibres (CF) from RS. The new method produced CF with a higher yield (37%) than the alkaline process (29%), more hydrophilic, and with a lower tendency to aggregate. Despite the slightly different degree of purification detected by the chemical and FTIR analysis, both fibres exhibited similar crystallinity, thermal behaviour, morphogeometric characteristics, and aspect ratio distributions (20–60). Both CF showed similar reinforcing capabilities in methylcellulose/gum Arabic films, enhancing the film stretchability and resistance to break by about 33% and 20%. Non-noticeable changes in water vapour permeability and the light internal transmission were observed, indicating good compatibility CF-polymer matrix. Therefore, using the ultrasound-heating method to obtain CF is an eco-friendlier process than the alkaline treatment, supplying suitable fibres as industrial reinforcing agents.Industrial relevanceUltrasound, an emerging technology in food processing, combined with reflux heating, can be a green alternative for obtaining cellulose microfibres for industrial applications. The new combined method was faster than the alkaline process (1.5 h vs. 6 h) and was more environmentally-friendly since it does not require a strong alkaline solution. Besides, both cellulose microfibres exhibited similar performances when incorporated into a polymer matrix. These results boost knowledge in the food packaging field, as well as the valorisation of agro-industrial wastes for industrial applications.