Dietary fibre content of dry and processed beans

Common beans (Phaseolus vulgaris L.) are a good source of protein, vitamins, minerals and especially dietary fibre. As beans are never eaten raw, the effects of soaking, cooking, soaking–cooking and canning on soluble, insoluble and total dietary fibre contents of beans are studied. Total dietary fibre content was determined by enzyme-gravimetric method. The fraction of insoluble dietary fibre was corrected for the content of resistant starch, determined as part of the total starch in insoluble fibre. The results indicate that thermal processing decreased the insoluble fibre content, and consequently the total dietary fibre content of beans. Soaking and cooking of beans significantly (P⩽0.05) increased the resistant starch content. The data on dietary fibre content of processed food are much more relevant than those of raw food. Thus food composition tables should contain as much data on processed food as possible.     

Indigestible fraction of okara from soybean: composition,physicochemical properties and in vitro fermentability by pure cultures of <Emphasis Type="Italic">Lactobacillus acidophilus</Emphasis> and <Emphasis Type="Italic">Bifidobacterium bifidum</Emphasis>

Major non-digestible components of soybean seeds and okara were determined by an in vitro enzymatic-physiological method, alternative to dietary fibre. Total indigestible fraction was higher in okara (41.6%) than in seeds (28.5%), and consisted of soluble and insoluble fractions, mainly composed of non-starch polysaccharides, klason lignin and resistant protein. Total protein was lower in okara (32.29%) than in seeds (46.97%), as were oil (14.72% okara–20.89% seeds) and ash contents (3.18% okara–4.60% seeds). In vitro digestibility of protein was lower for okara (84.3%), than for soybean seed (91.8%). Moreover, okara showed high swelling (10.54 ± 0.14 mL/g d.w.) and water retention capacity (8.87 ± 0.06 g/g d.w.) and was fermented in vitro to a greater extent by Bifidobacterium bifidum (29.8%), than by Lactobacillus acidophilus (8.3%). For its composition, physico-chemical properties and bifidogenic capacity in vitro, okara is a potential candidate to be a prebiotic fibre-rich ingredient of new functional foods. An erratum to this article can be found at     

Structural and functional characteristics of dietary fibre in beans,lentils, peas and chickpeas

To better understand the role that dietary fibre plays in the health benefits of pulses, the cell wall polysaccharides of pulses were characterized. To allow comparison between this data and nutritional studies, cooked chickpeas, lentils, beans and peas were used rather than raw seeds. Insoluble fibre, soluble fibre, resistant starch and oligosaccharide fractions were isolated using digestive enzymes at 37 °C. Prebiotic galacto-oligosaccharides, including raffinose, stachyose and verbascose made up between 3.5 and 6.9% of the cooked pulses (dry weight basis). Pulse fibre is pectin rich, with most being found in the soluble fibre fraction. The soluble fibre fraction is a diverse mixture of polysaccharides of varying sizes and solutions of soluble fibre exhibit a range of viscosities depending on the pulse type. The sugars which make up the insoluble fibre fraction suggest a large cellulose component. Microscopic examination of cooked whole pulses showed that a large fraction of the starch was partially gelatinized and contained within intact cell walls whereas boiled flour pastes had few ungelatinized granules. After simulated upper-gut digestion, some starch remained inaccessible to digestive enzymes. Cell walls of pulses modulate starch gelatinization and reduce enzymatic hydrolysis, which may account for the low glycemic response attributed to pulses.     

Characterization of a fibre-rich powder prepared by liquefaction of unripe banana flour

The development of nutraceutical ingredients is of current interest for the food industry. A fibre-rich powder (FRP) was prepared by liquefaction of raw banana flour (RBF) and its chemical composition, water- and oil-holding capacity, and antioxidant capacity were evaluated. Total dietary fibre (TDF) was higher in FRP than in the RBF, but the total starch (TS), potentially available starch (AS) and resistant starch (RS) contents were lower in the processed product, since the liquefaction process involves granular disruption and starch hydrolysis, resulting in reduced TS and AS and increased TDF. The reduced RS content is also explained by the loss of granular integrity, which is the main factor responsible for the indigestibility of native banana starch. Total indigestible fraction content of FRP was relatively high, the soluble fraction being lower than the insoluble portion. A very fast reduction of DPPH was observed in the presence of FRP, indicating that polyphenols in this preparation efficiently quench free radicals. Tested at various temperatures, the FRP and RBF exhibited similar water-and oil-holding capacities. The main difference was observed in water-holding capacity at 80 °C, where FRP was less efficient than the raw material, a fact associated with starch gelatinization in RBF treated at that temperature. FRP might be a potential ingredient for development of products with high TDF and indigestible fraction contents, as well as important antioxidant capacity.     

Evaluation of physico-chemical and sensory quality of frozen green grass pea (Lathyrus sativus L.)

The quality of grass peas (cv. Krab) intended for freezing was estimated at four degrees of seed maturity. The retention of basic physico‐chemical in dices such as dry matter, sugars, dietary fibre, total acids, total nitrogen, protein nitrogen and ash, as well as the sensory quality of frozen seeds prepared for consumption were used as the criteria in determining the overall quality value. Relative to fresh grass peas, the losses in cooked frozen seeds reached 47–64% for the content of reducing sugars, 36–53% of total sugars, 7–14% of starch, 2–4% of dietary fibre, 13–16% of total acids, 8–9% of total nitrogen and 4–6% of protein nitrogen. In cooked frozen seeds, differences between the first and the fourth maturity degree reached 47% in the case of dry matter content, 71% for starch, 166% for dietary fibre, 12% for acids, 51% for total nitrogen and 94% for protein nitrogen. The sensory quality of the cooked frozen grass peas was estimated to be from 4.17 to 4.77 on a 5‐score scale, and decreased with increasing seed maturity.     

Wet Fractionation of Hard-to-Cook Bean (<Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> L.) Seeds and Characterization of Protein,Starch and Fibre Fractions

A 2³ factorial design with four replicates of the central trial was used to evaluate wet-fractionation conditions for complete use of hard-to-cook (Phaseolus vulgaris L.) seeds. Tested variables were flour/water ratio (1:5, 1:7.5 and 1:10 w/v), pH (8, 9.5 and 11) and a soaking time (1, 2 and 3 h). The optimum conditions (1:10 w/v flour/water ratio; pH 8; and 1 h soaking time) were determined by the percentages of protein and starch recovery. Three fractions were obtained by the process: a protein isolate, starch fraction and fibrous residue. Isolate crude protein content was 73.03%; its in vitro digestibility was 76.7%, and its amino acids concentrations, except for methionine and cysteine, met essential amino acids requirements for preschool children and adults. Total starch content was 71.41% with an amylose content of 21.46% and an amylopectin content of 78.54%. Total dietary fibre in the fibrous residue was 42.12%, with 81.10% insoluble fibre and 18.91% soluble fibre. The protein isolate’s high protein content, the purity of the starch fraction and high proportion of insoluble fibre in the fibrous residues show wet fractionated hard-to-cook bean to be a promising source of functional ingredients with possible food industry applications.     

Effect of variety and processing on nutrients and certain anti-nutrients in field peas (Pisum sativum)

The effect of variety and processing (soaking, cooking and dehulling) on nutrients and anti-nutrients in field peas (Pisum sativum) was investigated. Analysis of variance showed that variety had a significant effect on crude protein, starch, ash, soluble dietary fibre (SDF), insoluble dietary fibre (IDF), total dietary fibre (TDF), trypsin inhibitor activity (TIA), minerals, phytic acid, sucrose and oligosaccharides. Soaking and cooking increased protein content, IDF, TDF, Ca, Cu, Mn and P in peas whereas ash content, Fe, K, Mg, Zn, sucrose and oligosaccharides were reduced. TIA was increased by soaking but reduced by cooking. Cooking was more effective than soaking in reducing oligosaccharides. Dehulling increased crude protein, starch, K, P, phytic acid, stachyose and verbascose content but reduced SDF, IDF, TDF, Ca, Cu, Fe, Mg and Mn.     

The antioxidant activity and composition of fresh, frozen, jarred and canned vegetables

Regular consumption of dietary antioxidants may reduce the risk of several serious diseases. As vegetables are a major source of antioxidants it is desirable to assess their antioxidant activity and compare different processing and preparation methods. The total antioxidant activity was determined in water- and lipid-soluble extracts from fresh, stored and frozen vegetables. The contribution of individual compounds to total antioxidant activity was estimated. In stored vegetables at ambient or chill temperatures antioxidant activity declined. Blanching and freezing of peas and spinach reduced water-soluble antioxidant activity by 30 and 50%, respectively, thereafter levels remained constant on storage at −20 °C. Samples of frozen peas and spinach purchased from retail outlets had substantially higher antioxidant activity than canned or jarred samples. In a comparison of cooking methods, microwave and boiling for short periods had a negligible effect on total antioxidant activity, but substantial losses occurred after prolonged boiling in water.     

Significance of lipid binding on the functional and nutritional profiles of single and multigrain matrices

Lipid fractions and starch- and protein-lipid binding of single and blended oat, rye, buckwheat and wheat flour, dough and bread matrices were investigated, and results correlated with the functional and nutritional properties of the grain matrices during mixing and baking. Non-starch lipid was the most prominent fraction in terms of absolute content and as a percentage of total lipids. Free lipids, starch lipids and bound lipids were, respectively, the major, intermediate and minor lipid fractions in flours, doughs and breads. Great differences in total lipid content due to sampling result in divergences amongst lipid fraction content and distribution, especially for starch and bound lipid fractions. Lipids bound to proteins during dough mixing are translocated and bound to starch during baking. In blended samples, the higher fibre content seems to provoke a reduction of the lipid–protein and lipid–starch linkages due to interactions between fibres and endogenous biopolymers. Starch lipid showed the most significant correlations with parameters related to dough and bread performance during breadmaking, especially over the mixing step. Valuable fresh bread functional characteristics, such as high specific volume and high sensory score for softness and overall acceptability, correspond to a starch lipid’s increase due to mixing. The higher the free and starch lipids decrease by reason of temperature treatment—baking—the larger the starch hydrolysis and the higher β-glucans and total dietary fibre contents.     

Evaluation of nutritional and physico-mechanical characteristics of dietary fiber-enriched sweet potato pasta

The objective of the present study was to enhance the utilization of sweet potato (Ipomoea batatas Lam.) as a slowly digestible food by developing dietary fiber-fortified pasta from it. Swelling index as well as cooking loss (%) was more for the pasta made from the pale cream-fleshed variety, Sree Arun (V1) than that from the orange-fleshed variety, Sree Kanaka (V2), and least values were obtained in the pasta fortified with rice bran. Fortification with oat bran, wheat bran, and rice bran elevated the crude protein content to 5–10% in the pasta. Total and insoluble dietary fiber fractions were more in the pasta from Sree Arun (6–17 and 5–14%, respectively) than those from Sree Kanaka (5.25–15 and 3.7–11%, respectively) with the highest values in the wheat bran-fortified pastas. All the fiber-fortified pastas (10 and 20% level of fortification) had slow and progressive starch digestibility over 2 h compared to the control pastas. While approximately 70% of the total starch was rapidly digestible for the control pastas from both the varieties, this was drastically reduced to 45–54% in the test pasta from V1 and 37–50% in V2. Accordingly, the retention of resistant starch (RS; undigested starch after 2 h) in the control pastas was only 14–17%, while it was 38–49% in the test pastas from V1 and 39–55% from V2, with higher RS in the 20% fortified pastas. Texture profile analysis showed that the firmness (N) and toughness (Ns) increased with increase in the fortification level of fiber sources. The progressive starch digestibility coupled with high-resistant starch after 2 h indicated the potential of fiber-fortified sweet potato pasta as an ideal food for the diabetic and obese people.     

Chemical composition and in vitro starch bioavailability of Phaseolus vulgaris (L) cv Mayocoba

Common beans of the Mayocoba variety were cooked (178 min) and evaluated regarding their chemical composition and starch digestibility in vitro. Mean physical characteristics of the Mayocoba grain were: thousand‐kernel weight, 443.0 (±0.98)g; length, 12.45 mm; width 7.84 mm and thickness, 6.44 mm. Total starch content in Mayocoba bean was 40.24% (dmb). The available starch was 22.87%, whereas resistant starch accounted for 6.4% and retrograded resistant starch represented 3.3% of the cooked seed weight. None of these values changed with storage time. The Mayocoba variety presented values of soluble indigestible fraction of approximately 8.0% and insoluble indigestible fraction of 36%, which did not change with storage. Both simple enzymatic hydrolysis rate and hydrolysis index (HI = 36%) indicated a slow hydrolysis of Mayocoba starch. HI‐based predicted glycemic index was 39%, all of which suggested a ‘slow carbohydrate’ feature for this bean. Copyright © 2004 Society of Chemical Industry     

Fermentation of resistant food starches by human and rat intestinal bacteria

Resistant starches prepared from maize and peas were fermented in vitro with rat or human intestinal bacteria. With both inoculum types, degradation of pea starch after 24 h incubation (0 and 47% utilised by rat and human organisms, respectively) was markedly slower than that of maize starch (73 and 85%) and was incomplete even after 7 days' incubation; degradation of both starches was slower than with soluble starch or sucrose. The slow degradation of pea starch was not due to the presence of intact cell walls. Qualitatively, the production of C2-C4 volatile fatty acids was similar for all substrates and both inoculum types but there were some quantitative differences. If resistant food starches are to be regarded as dietary fibre, then, like ‘true’ fibre, any physiological effect in vivo may depend on the type of starch involved.     

The impact of resistant starch on characteristics of gluten-free dough and bread

The study focused on partial replacement in gluten-free breads of corn starch with tapioca and corn resistant starch preparations. The use of resistant starch resulted in the increase of storage and loss moduli of the dough, and the lowering of loss tangent, which indicates its more elastic character. The incorporation of resistant starch reduced creep and recovery compliance and elevated zero shear viscosity. Modified doughs displayed higher starch gelatinization temperatures and lower viscosities that were proportional to the share of RS. It was found that the loaves baked with the share of resistant starch had less hard crumb than bread without RS addition. The crumb hardness diminished with the increasing amount of applied RS preparation. The addition of resistant starch raised total dietary fibre, by up to 89%, as compared to control (bread without RS addition). The most pronounced change was observed for insoluble dietary fibre (increase 137%), while only slight increase was found for its soluble fraction (18%).     

Sensory and nutritional attributes of fibre-enriched pasta

The objective of this study was to evaluate the impact that the incorporation of resistant starch type II (RSII), resistant starch type IV (RSIV) and oat bran (OB) have on sensory and nutritional quality of pasta. RSII, RSIV and OB were incorporated into recipes in four proportions (w/w): 2.5, 5.0, 7.5, and 10.0 g/100 g. Resistant, digestible and total starch were measured in cooked pasta. An in vitro digestion and sensory analysis of pasta were performed in order to estimate glycemic index. Results showed that both, the type and amount of added fibre influence nutritional quality of pasta. Incorporation of RSII into pasta formulation generates an additional quantity of resistant starch content in cooked pasta. Differences in in vitro digestibility of pasta can be appreciated. RSIV presented the greatest effect on total starch hydrolysis. The lower glycemic index was obtained with addition of RSIV and RSII at 7.5 g/100 g and 10.0 g/100 g. Sensory analysis showed high scores for overall acceptability for Control, RSII and RSIV samples. Results suggest that by using insoluble fibre it is possible to enhance the nutritional quality of pasta, without affecting its sensory properties negatively.     

Effect of the Addition of Common Bean (Phaseolus vulgaris L.) Flour on the In Vitro Digestibility of Starch and Undigestible Carbohydrates in Spaghetti

Abstract: Spaghetti is considered to be a slowly digestible starch food, a feature ruled by the particular physical properties of the product. Several studies have been reported to increase nutritional value of spaghetti, using legumes. We have studied the addition of common bean flour on the starch in vitro digestibility. Spaghetti was prepared with semolina and different concentrations of common bean flour (0%, 15%, 30%, and 45%, w/w). Proximate analysis, optimal cooking time, and cooking loss were estimated in crude spaghetti. Total, available, and resistant starches, indigestible fractions, and in vitro starch hydrolysis kinetics were accomplished in cooked spaghetti. Pasta with 30% and 45% of common bean flour showed higher values of protein. Particularly, the lowest cooking time was observed for composite spaghetti with 45% of common bean flour. There was a significant increase in cooking loss when common bean flour in the composite was added. Composite spaghetti samples with increasing common bean flour showed decreasing values of total starch but an important increase in the resistant starch (RS) level and indigestible insoluble fraction values. Plain pasta made with semolina showed the highest enzymatic hydrolysis rate, which decreased when common bean flour was added to the spaghetti. Spaghetti with a higher level of common bean flour was more slowly available, which may have positive implications for human health.     

Towards an updated methodology for measurement of dietary fiber,including associated polyphenols,in food and beverages

The analytical dietary fiber (DF) methods most widely used today were developed to determine non-starch polysaccharides and lignin. Updated dietary fiber definition includes all indigestible plant food constituents. Recent methods have proposed the measurement of resistant starch and oligosaccharides, but other major indigestible constituents such as polyphenolic compounds and resistant protein are still omitted in dietary fiber analysis. There is scientific evidence that an appreciable amount of dietary polyphenols are associated with the dietary fiber matrix, being a fermentable substrate for bacterial microflora. The objective of this work was to show polyphenols compounds are major constituents of dietary fiber and to propose a procedure for their measurement. Results showed that polyphenols are major constituents of DF, accounting from 1.4% to 50.7% (dry weight) of insoluble dietary fiber in plant foods and from 2.9% to 62.8% of soluble dietary fiber in common beverages.     

Dietary fibre content and antioxidant activity of Manto Negro red grape (Vitis vinifera): pomace and stem

The general composition of two by-products of the vinification process of the Manto Negro red grape (Vitis vinifera) variety, namely pomace and stem, were determined. Both by-products present high contents of total dietary fibre (TDF), comprising three fourths of the total dry matter. The pomace had high protein (12.2%) and oil (13.5%) values and the stem large amounts of extractable polyphenols (11.6%). Due to the high fibre content, the soluble dietary fibre (SDF), insoluble dietary fibre (IDF), uronic acids (UA) and Klason lignin (KL) were analysed in both samples. Notable were the high percentage of soluble fibre (15%) in relation to the total dietary fibre for the pomace, as well as the high content of Klason lignin (KL) in both by-products, especially in the stem (31.6%). This fraction (KL) has important amounts of condensed tannins (CT) and resistant protein (RP).     

Antioxidant protection of white grape pomace on restructured fish products during frozen storage

White grape antioxidant dietary fibre (WGDF) was obtained from white grape (Vitis vinifera, var. Airén) pomace from wine production. The antioxidant capacity of WGDF was determined in minced fish muscle (MFM) during frozen storage. Concentrations of 0, 2, and 4% WGDF ((0-WGDF), (2-WGDF), and (4-WGDF) respectively) were added to MFM samples. Analyses were carried out immediately after preparation of samples and over 6 months of storage at −20 °C. WGDF was characterized in terms of dietary fibre (DF) (insoluble and soluble), total polyphenols and antioxidant capacity, and multifunctional antioxidant assays were done on all the MFM samples. The addition of white grape DF considerably delayed lipid oxidation in minced horse mackerel muscle during the frozen storage. Vacuum-packing the sample with 2% WGDF significantly enhanced the antioxidant properties of WGDF.     

RELATIONSHIPS BETWEEN PHYSICAL-CHEMICAL COMPOSITION OF RAW PEAS AND SENSORY ATTRIBUTES OF CANNED PEAS

Two pea cultivars (Citrina and Warindo) at four commercial sizes (superfine, very-fine, fine and middle) were selected for a study of their physical-chemical parameters of raw and sensory attributes after canning. To determine the relationships between the physical-chemical parameters and the sensory attributes, Principal Component Analysis (PCA) was applied. About 65% of the total variation in the physical-chemical parameters and sensory attributes was expressed by two PCA Factors. Mealiness was an important sensory attribute in determining the sensory quality of pea, and was related to tenderometric value, alcohol insoluble solids and starch content of raw seeds. General acceptance of canned peas by panelists was based on titratable acidity, green color and juiciness. Raw peas should be selected according to their dry matter, starch and titratable acidity, if they are to reach the consumer in an appetizing state when canned. This quality is mainly determined by general appearance, juiciness and flavor.     

Chemical Composition,Starch Bioavailability and Indigestible fraction of Common Beans (Phaseolus Vulgaris L.)

In Mexico, consumption of beans represents 15% of the normal diet of the population in rural zones. Four common bean varieties cultivated in Mexico were studied regarding their chemical composition, starch digestibility and indigestible fraction. The protein level in the samples Huasteco, Tacana and TLP 19 was not different (α = 0.05), but Veracruz cultivar had the highest protein and ash content, and the lowest lipid level. Differences in chemical composition were determined in the cultivars studied. Total starch (TS) ranged between 33.6 and 36.7%, and the cultivars Tacana, TLP 19 and Veracruz were not different in starch content (α = 0.05). The available starch (AS) determined represented between 74 and 87% of TS, due to the resistant starch content and perhaps some complex formed between starch and protein or starch and polyphenols, by the high level of the indigestible fraction determined in the beans. The in vitro α‐amylolysis rate was similar for the different varieties, except for Veracruz cultivar which presented a slightly lower hydrolysis rate.