The effect of field drying on the non-structural carbohydrate composition in vetch hay

Common vetch (Vicia sativa L) was harvested and allowed to dry in the open air. The composition of fresh forage in non-structural carbohydrates varied markedly between years, the contents of sugars and starch in both leaves and stems being much higher in 1990-91 than 1991-92. Field drying produced a significant decrease in the amounts of these carbohydrates. The total losses of sugars and starch in hay, expressed as losses of dry matter, ranged from 28 to 15 g kg^-1, depending on the year.     

Short‐chain fatty acid content in the hindgut of rats fed various composite foods and commercial dietary fibre fractions from similar sources

The fermentability of indigestible carbohydrates and content of short‐chain fatty acids along the hindgut of rats were investigated using plant materials of importance in the Swedish diet (instant potato powder, apples and oat flakes). Results with the composite food products were compared with commercial fibre fractions obtained from similar sources, ie potato fibre, apple pectin and β‐glucan‐enriched oat fibre. The materials were incorporated into diets yielding a concentration of 60 or 70 g kg^?1 indigestible carbohydrates. The fermentability of indigestible carbohydrates was high with all diets, between 79 and 90%. All substrates except the pure apple pectin generated intermediate to high proportions of butyric acid in the caecum (15–22 vs 8%). The potato products gave high concentrations of butyric acid in the distal colon. The potato powder, ie the diet with the highest content of resistant starch (22 g kg^?1), also gave the highest proportion of butyric acid in the distal colon (19%), which was higher than the proportion in the caecum with the same substrate (15%) (P < 0.005). The composite foods promoted a higher proportion of butyric acid in the distal colon as compared with the commercial fibre fractions (P < 0.05). © 2002 Society of Chemical Industry     

EFFECT OF SUGARS ON THE THERMAL AND RETROGRADATION PROPERTIES OF OAT STARCHES

The thermal and retrogradation properties of oat starches from two cultivars (NO 753-2 and AC Stewart) were characterized in the presence of glucose, fructose and sucrose at a concentration of 36% w/v. In both oat starches, amylose leaching (AML) and swelling factor (SF) decreased in the presence of sugars (sucrose > glucose > fructose). These decreases were more pronounced in AC Stewart starch. The decrease in AML showed that sugars interact with amylose chains within the amorphous regions of the starch granule. The gelatinization transition temperature and the enthalpy of gelatinization increased in the presence of sugars (sucrose > glucose > fructose). The above increase was also more pronounced in AC Stewart starch. The decrease in SF and the increase in gelatinization parameters indicated that these changes were influenced by the interplay of factors such as starch-sugar interaction, changes in water structure in the presence of sugars, and the antiplastizing properties of sugars relative to water. The retrogradation enthalpy and the X-ray diffraction intensities of NO 753-2 and AC Stewart starch gels (stored at 4C) increased in the presence of sugars (glucose > fructose > sucrose). These changes were more pronounced in NO 753-2 starch. The results showed that interaction (during storage) between leached amylopectin and sugar molecules was the main causative factor influencing oat starch retrogradation.     

Proximal composition and in vitro digestibility of starch in lima bean (Phaseolus lunatus) varieties

BACKGROUND: Beans are rich and inexpensive sources of proteins and carbohydrates around the world, but particularly in developing countries. However, many legume varieties are still underutilized. In this study, physical characteristics of the seeds of three Phaseolus lunatus cultivars were characterized. Also, the chemical composition and starch digestibility in the cooked beans were assessed. RESULTS: ‘Comba floja’ variety exhibited the highest thousand‐kernel weight whereas the lowest was found in ‘comba violenta’. This agrees with seed dimensions: ‘comba floja’ had the Longest seeds (16.36 mm) and ‘comba violenta’ the shortest ones (13.98 mm). All samples exhibited high protein content, but levels in ‘comba blanca’ variety (216 g kg^?1) were lower than the in other two cultivars. Total starch (370–380 g kg^?1) and potentially available starch content (330–340 g kg^?1) were similar in the three varieties. Resistant starch level in the cooked seeds ranged between 38 and 45 g kg^?1. Low enzymatic hydrolysis indices (HI) were recorded (30.2–35%), indicating a low digestion rate for Phaseolus lunatus starch. HI‐based predicted glycemic indices ranged between 34% and 39%, which suggests a ‘slow carbohydrate’ feature for this legume. CONCLUSION: Phaseolus lunatus beans appear to be a good source of protein and slow‐release carbohydrates with potential benefits for human health. Copyright © 2007 Society of Chemical Industry     

Carbohydrate constituents of some nigerian maize varieties grown at three soil nitrogen levels

Of eight varieties of maize analysed, average values for constituent carbohydrates in g/100g dry matter were: soluble sugars, 1·61; starch, 62·04; water-soluble polysaccharides, 2·60; alkali-soluble polysaccharides, 6·85 and cellulose, 1·08. Lignin varied from 1·18 to 1·86%. Significant varietal differences (P < 0·05) were found for the carbohydrate fractions, although differences within varieties due to nitrogen fertilisation were not significant. Soluble sugars and starch, which contribute appreciably to the energy value of the maize, ranged between 56·68% for WCUI and 67·12% for Lag ABCD. Predicted digestible energy (DE) and metabolisable energy (ME) values for pigs were in the range 4005–4073 kcal/kg and 3881–3947 kcal/kg, respectively whilst metabolisable energy for poultry varied between 3692 and 4007 kcal/kg.     

Changes in the composition and carbohydrate constituents of okra (Abelmoschus esculentus, Linn.) with age

Changes which occurred in the proximate composition, concentrations of free sugars, high molecular weight carbohydrates (water-soluble polysaccharides, starch hemicellulose and cellulose) and lignin in four varieties of okra when harvested at different ages have been studied. Samples were collected from the field at 1, 4, 7 and 10 days after flowering. Crude protein, which initially ranged from 19·9 to 24·7 g/100 g DM, decreased with age whilst crude fibre, 12·5–16·7 g/100 g DM, increased with age. Ether extract varied between 1·60 and 2·19 g/100 g DM whilst ash was 8·00–8·59 g/100 g DM. Available carbohydrates (starch + sugars) ranged from 11·2 to 13·1 g/100 g DM whilst unavailable carbohydrates increased from 33·9–42·0 g/100 g DM to 51·9–59·7 g/100 g DM.Overall varietal differences were apparent for ethanol-soluble sugars and the structural carbohydrates while differences among the means due to age were significant (P < 0·05).     

Blockage of available lysine at different stages of infant cereal production

Determination of available lysine was used to assess the heat damage produced during the processing of cereals for infant foods. The infant cereals analysed were: wheat, 7 and 8 cereals, rice, rice–corn, rice–corn–soy and oat. Lysine losses during the toasting of flours ranged between 14 and 29%. Roller‐drying treatment caused considerable heat damage, with a 53% decrease of available lysine in roller‐dried rice–corn–soy. However, oat flour was less susceptible, with a 5% reduction in available lysine during roller‐drying. © 1999 Society of Chemical Industry     

Chemical composition,antioxidant capacity and functionality of raw and processed Phaseolus lunatus

The nutrients, non‐nutritional components and bioactive compounds, as well as the antioxidant capacity of raw, cooked, tray and drum‐dried Phaseolus lunatus have been quantified. Likewise, the minerals, soluble carbohydrates, total polyphenols and tannins in the soaking and cooking waters were quantified. In addition, the functional properties such as the water and oil absorption indexes and the emulsifying and the foaming capacities were studied. The protein content of the raw beans was 24.98% and decreased, like calcium, magnesium and potassium, with the soaking and cooking processes; these losses are found in the soaking and cooking waters. Drum drying decreased anti‐nutritional factors like trypsin inhibitors (66.09%) and cyanhydric acid (50.36%). Similarly, soluble fiber, available starch, total starch, and soluble sugars diminished, while total and insoluble fiber and resistant starch increased. The content of total polyphenols, tannins and antioxidant capacity decreased with thermal processing, being drum drying the process that least diminished antioxidant capacity. Likewise, the water absorption index was increased by 85% and 161.5% with processing. It was shown that P. lunatus is an important source of nutrients and can be consumed in whole bean form or used as a functional ingredient to be added in the development of new products. Copyright © 2007 Society of Chemical Industry     

Analysis of the testaless seeds of chrysophyllum albidum: Nutritional aspects

The testaless seeds of Chrysophyllum albidum G Don from Nigeria were analysed and found to contain saponins with a foaming index < 100, 71 g kg^?1 crude fibre, 109 g kg^?1 total ash, 316 g kg^?1 carbohydrates, 364 g kg^?1 proteins and 52 g kg^?1 fixed oil on dry weight basis. They were also found to have appreciable amounts of K, Ca, P and Mg. Further analysis of the carbohydrates showed the presence of starch and the reducing sugars arabinose, galactose, glucose and mannose. The profile of amino acids showed the seeds to be rich in the essential amino acids lysine, threonine, leucine, isoleucine and phenylalanine. The fatty acids of fixed oil include 16–3% palmitic acid, 5–9% stearic acid, 41–3% oleic acid, 30–9% linoleic acid and 1–6% arachidic acid.     

In vitro Starch Digestibility and Nutritionally Important Starch Fractions in Cereals and Their Mixtures

Dietary carbohydrates are characterized with respect to both chemical composition and likely site, rate and extent of digestion. Starch is divided into rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). The present investigation aimed at evaluating the effect of starch source on nutritionally important starch fractions and the extent of in vitro starch digestion in four processed cereals, namely rice, ragi (Eleusine coracona), wheat, jowar (Sorghum vulgare) and their mixtures in varying proportions, using controlled enzymatic hydrolysis with pancreatin and amyloglucosidase. Rapidly available glucose (RAG) was also measured to derive a starch digestion index (SDI). The total starch and amylose content in the raw cereals ranged from 21 — 26.6 and 12.6 — 20.7 g/100 g, respectively. Among the four basic cereals, roti (flat, unleavened pancake, diameter 12 cm) produced from ragi had highest total starch, RDS and SDI. However, in mixtures containing two or more cereals RDS and SDI were lower than those observed in single cereals. Significant correlations were observed between RAG and SDI, or RDS, respectively (r=0.91, r=0.96, p<0.01). An inverse relation between amylose content and SDI (r= ‐0.78, p<0.01) indicates the influence of amylose on the extent of starch digestion. The results highlight the importance of starch source in determining the starch fractions of processed cereals and their mixtures. The simple in vitro measurement of starch fractions could serve as a tool for characterizing dietary carbohydrates with respect to their digestion in the gut.     

Carbohydrate composition of different varieties of cowpea (Vigna unguiculata)

Twenty varieties of cowpea with the following proximate composition: dry matter, 87–94%; crude protein, 24–33% ether extract, 1–2%; crude fibre, 2–5% and ash, 2–5% were analysed for sugar contents, starch, cell wall carbohydrates and lignin. The legume seeds exhibited a total carbohydrate content ranging from 56% to 68%, the major constituent being starch. Starch values as high as 45% to 48% were obtained for some varieties although most values ranged between 37% and 42%. Ethanol-soluble sugars were verbascose, stachyose, sucrose and raffinose in varying amounts but there were only traces of fructose and glucose. Samples had total soluble sugar contents of 6% to 13%. Values for unavailable carbohydrates for most samples were 11% to 13%. Lignin was very low and ranged from 0·6% to 1·8%.     

Characteristics of the Starch in the Tubers of Dropwort (Filipendula vulgaris)

The yield, isolation and properties of starch and its fractions from dropwort (Filipendula vulgaris) have been investigated. The starch content of tubers ranged from 9.5 to 14.0%. The size of starch granules was 2 to 12 μm. Fertilization seems to increase their size. The granules stained relatively faintly. The polarization cross was strong and centric. Thr amylose content of starch was 27 to 32%, and the molecular weight, corresponding to 50% of the starch components. was about 10⁶. Gelatinization properties were fof wheat type.     

In vitro Starch Digestibility and Nutritionally Important Starch Fractions in Processed Roots and Tubers

In view of the nutritionally important starch fractions it has become essential to generate data on starch digestibility of commonly used foods. The present investigation was aimed at evaluating the effect of processing on the nutritionally important starch fractions and the extent of in vitro starch digestibility in six roots and tubers commonly consumed in the Indian cuisine, using controlled enzymatic digestion with pancreatin and amyloglucosidase. The samples were subjected to open‐pan and pressure cooking. Rapidly available glucose (RAG) was also measured to derive a starch digestion index (SDI), a measure of the relative rate of starch digestion. The total starch and amylose content in the raw samples ranged from 41% (w/w) to 80% (w/w) (dry basis) and 0.91 to 26.80% (w/w) (dry basis), respectively. Pressure cooking of roots and tubers significantly (p<0.05) decreased the amylose content. The levels of the individual starch fractions varied depending on the cooking method and were characteristic for each sample. Processing significantly influenced the various starch fractions in yam and knollkohl. The SDI of samples subjected to the two cooking methods was only different for beet root and radish. Radish and carrot contained the highest dietary fiber content. The simple in vitro measurement of starch fractions could serve as a tool for characterizing dietary carbohydrates with respect to their digestion in the intestine.     

A study of the effect of the drying process on the composition and physicochemical properties of flours obtained from durian fruits of two ripening stages

Durian cv. Monthong with two ripening stages (unripe and fully ripe) was subjected to microwave vacuum drying (MWD) at 5.49 W g^?1 and hot air drying (HAD) at 60 °C. With an increase in ripening degree, the starch content was significantly (P ≤ 0.05) decreased from 40.08–40.42% to 9.44–11.76%. X‐ray diffraction indicated that the crystalline pattern was changed from starch to sucrose. The starch granule morphology of durian flour was conserved for both drying conditions. Peak gelatinisation temperatures of MWD and HAD flours were increased significantly (P ≤ 0.05) from 56.71–57.32 to 60.71–61.23 °C. Using different drying methods, MWD flour had less a*‐value (P ≤ 0.05) than HAD flour. The peak viscosity and trough of the HAD unripe durian flour (5.92 RVU and 3.45 RVU, respectively) were significantly (P ≤ 0.05) lower than those of the MWD unripe durian flour (34.32 RVU and 11.57 RVU, respectively).     

Physicochemical changes of oat seeds during germination

The physicochemical properties of native and germinated oat seeds cultivated in China and their correlations were investigated. The growth curve during germination of oat seeds was described. The malt yield was 84% at the end of malting. The losses by removing of shoots and rootlets were the major cause of the total dry matter losses in the last 24 h of germination. With total starch enzymes activities increasing continuously, the starch content decreased considerably from 60% to 20%, and the reducing and soluble sugars contents increased. Oat seed kernel protein increased slightly, but the lysine content increased almost 30% at the end of germination. The phytic acid content declined from 0.35% to 0.11% during germination. There is a significant correlation among compositions including starch, protein, free and reducing sugars, free amino acid, and phytic acid. A close correlation also was found between the colour of malt flour dried at 50 °C and the length of shoots and rootlets. The results suggest that oats grown in China are a good food material and that germination can improve their nutritional properties.     

Comparison of the contribution to soil organic matter fractions,particularly carbohydrates,made by plant residues and microbial products

Soil was incubated with ¹⁴C-ryegrass or ¹⁴C-glucose, fractionated and the distribution of radioactivity in six fractions and in their constituent sugars was compared. The fractions were (1) the light fraction (d < 2.00), (2) heavy fraction which was subdivided into (3) HCl soluble, (4) humic acid, (5) fulvic acid, and (6) humin. Sugars were released from soluble fractions by hydrolysis with 0.5M H₂SO₄, and from insoluble fractions by hydrolysis with 2.5M H₂SO₄ and 12M H₂SO₄ followed by 0.5M H₂SO₄. The light fraction contained the greater part of the radioactivity and the sugars in both types of incubation. The proportion of the radioactivity accounted for by sugars in the light fraction of the ryegrass incubation, initially 44%, decreased to 30% after 6 months incubation and to 19% after a year. In one of the glucose incubations, done with soil that had been dried prior to remoistening to 25% w/w and incubating, the proportion was 17% after incubation for one month; in the other, done on soil that had not been given a drying treatment and had a 35% w/w moisture content, it was 32%. In the ryegrass incubation, the sugars with the greatest specific activities were present in the light fraction. In contrast, in the glucose incubation, sugars in the HCl-soluble, fulvic and humic fractions had the highest specific activities. Carbon from ryegrass contributed more to the humic acid and humin fractions of the soil than did the carbon from glucose, whereas carbon from glucose made a greater contribution to the acid-soluble organic matter.     

Effect of microwave vacuum drying and hot air drying on the physicochemical properties of durian flour

Unripe durian cv. Monthong was subjected to microwave vacuum drying (MVD) at 1200, 1600 and 2200 W and hot air drying (HAD) at 40, 50 and 60 °C to produce durian flour. Drying rate of MVD and HAD was 0.34–0.58 kg water kg dry solid^?1 min^?1 and 0.02–0.06 kg water kg dry solid^?1 min^?1, respectively. An increase in drying rate by either increasing hot air temperature or increasing microwave power decreased the degree of crystallinity from 21.95% to 2.31% and from 7.72% to 4.05%, respectively. Moreover, the increased drying rate caused a decrease in endothermic enthalpy (ΔH_gel) and pasting properties. Starch content of the durian flour was 41.40–47.03%. The starch granule morphology of durian flour was disrupted which indicated gelatinisation of flour during drying. Due to a short drying process, the MVD flour had less a*‐value (P ≤ 0.05) than the HAD flour.     

Hydrolysis of fructans from Agave tequilana Weber var. azul during the cooking step in a traditional tequila elaboration process

In traditional tequila production, the heads of Agave tequilana Weber var. azul are cooked in brick ovens to hydrolyze the fructan content and release fermentable sugars. The juice generated during cooking (known as “cooking honey”) was collected periodically in a tequila distillery and characterized to study the efficiency of fructan hydrolysis. The complex structure of fructans from A. tequilana was confirmed. The generation of 5-(hydroxymethyl)-furfural, an increase in absorbance and °Brix, and a decrease in pH and apparent average degree of polymerization of fructans during cooking were observed. The conversion of fructans in the flowing honey increased gradually from 20% at the onset of cooking to 98% after 25.5 h, where fructose represented more than 80% of the total carbohydrates. The proportion of non-hydrolyzed fructans in the cooking honey collected before this time resulted in a total ethanol loss of 6% in the tequila distillery investigated.     

Oat Gum and β-Glucan Extraction from Oat Bran and Rolled Oats: Temperature and pH Effects

The extractability of oat gum from oat bran and rolled oats was studied using 12 treatment combinations in a factorial design (2x3x4x2) i.e. 2 oat products; 3 pH (8.0–10.5); 4 temperatures (5O–70°C); 2 replications. The extraction procedure involved: (a) alkaline treatment of flour and removal of starch residue; (b) isoelectric precipitation of protein residue [namely, protein concentrates (PC)]; (c) and alcohol precipitation of oat gum/β-glucan and collection of gum by centrifu-gation. Extracted oat gum ranged from 2.99–6.28% for oat bran and 1.82–5.24% for rollcd oats whereas β-glucan (in gum) ranged from 70–89% and 50–68%, respectively. Protein contents of the PC from oat bran was 69–91% and rolled oats 66–89%. Correspondingly, starch content of residues ranged from 30–63% and 61–47%. Oat gum/β-glucan extracted at pH 9.2/50°C or pH 10.5/50/55°C showed little or no starch contamination.     

Nutritive value and antinutritional factors in different varieties of Sesbania seeds and their morphological fractions

Four different Sesbania seeds, S. aculeata, S. rostrata, S. sesban (accession 10865D) and S. sesban (accession 15019D), were analysed for their physicochemical properties, nutritive values and antinutritional factors (ANFs) in order to assess feasibility of use as an unconventional food resource. Seeds of both the accessions of S. sesban were smaller in size but their seed coat+endosperm fractions were higher (56–57%) than those of S. aculeata and S. rostrata (49–51%). S. rostrata had a lower hydration capacity, hydration index, swelling capacity and swelling index than other seeds. The crude protein content in different seeds ranged from 29.1 to 33.1%, crude lipid 4.7–6.0%, crude fibre 10.9–15.8%, total crude carbohydrates 44.6–47.4% and gross energy 19.2–20.0 kJ/g. Except for isoleucine, histidine and tryptophan, all other essential amino acids were deficient compared to the FAO/WHO reference pattern. The seed fractions showed similar amino acid pattern to that of whole seed with slightly higher values. Palmitic, stearic, oleic, linoleic and linolenic acids were the major fatty acids (FAs) and the total unsaturated and essential FAs ranged from 78.1 to 82.3% and 77.2 to 80.3%, respectively, with S. aculeata having the highest value. The ranges of starch fractions in different seeds were: total starch 17.5–20.4%, digestible starch 7.3–10.2% and resistant starch 10.2–11.2%. The soluble sugar contents ranged from 8.8 to 10.6%. The ranges of antinutritional factors in different seeds were: total phenols 2.96–5.95%, tannins 1.97–2.25%, condensed tannins 1.82–5.14%, phytic acid 1.89–2.37%, saponins 0.52–1.46%, trypsin inhibitors 5.25–14.0 (mg trypsin inhibited per gram of sample) and lectin activity 10.2–20.5 units. There was a wide variation in the ANFs contents of seed coat+endosperm, and cotyledons.