The use of hydrogen peroxide for the digestion and determination of total nitrogen in chickpea (Cicer arietinum L.) and pigeonpea (Cajanus cajan L.)

The use of hydrogen peroxide as an alternative to catalysts in the determination of nitrogen in plant materials has been investigated. Nitrogen determination in leaf, stem and seed samples of chickpea and pigeonpea was carried out by three digestion procedures, using hydrogen peroxide (H₂O₂ digestion) without a catalyst, and with mercury or selenium as catalysts (catalyst digestions). The nitrogen values obtained by the three digestion procedures did not differ significantly from each other when examined by microKjeldahl (MKJ) using mercury as a catalyst, and by a Technicon auto analyser (TAA) using selenium as catalyst. The gradual addition of H₂O₂, as recommended previously, was found to be unnecessary. In view of the cost and health hazards implicated with the use of mercury and selenium for digestion, the procedure based on H₂O₂ digestion is preferable for large scale N determinations in plant tissue and seed samples of these pulse crops. The results sugest that the H₂O₂ digestion technique can be conveniently adapted for total N analysis in plant tissues and grain samples by either TAA or MKJ method.     

Nutrient Losses Due to Scarification of Pigeonpea (Cajanus cajan L.) Cotyledons

Outer layers of cotyledons of pigeonpea cultivar C 11 were successively scarified using a Tangential Abrasive Dehulling Device (TADD). Scarification for 0; 2, 4, 8, and 12 min resulted in the removal of 0, 6.7, 12.7, 25.3, and 36.9%, respectively, of powder fractions. The cotyledons and powder fractions at each level of scarification were analyzed for chemical composition, including minerals and trace elements, protein fractions, amino acid composition, and trypsin inhibitor acitivity (TIA). Protein, soluble sugars and ash of the dhal fraction (scarified cotyledons) decreased with increasing scarification time, while starch content increased. Considerable amounts of calcium (about 20%) and iron (about 30%) were removed by scarification for 4 min, but the process did not adversely affect protein quality in terms of amino acids. Trypsin inhibitors were not removed substantially by scarification.     

Nutritional quality evaluation of newly developed high-protein genotypes of pigeonpea (Cajanus cajan)

Two high-protein genotypes of pigeonpea (Cajanus cajan L), HPL 8 and HPL 40, were analysed for their nutritional quality characteristics, and the results were compared with those of normal-protein genotypes (C 11 and ICPL 211). The protein content of the high-protein genotypes was higher on average by nearly 20% but their starch content, the principal constituent of the seed, was lower by about 8%. The higher fraction (about 7%) of globulin, the major storage protein, was associated with a lower glutelin fraction in the high-protein genotypes. The amino acid composition (g per 100 g protein) of the high-protein genotypes was comparable with those of the normal-protein genotypes. However, the sulphur-containing amino acids methionine and cystine were noticeably higher (about 25%) in high-protein genotypes when results were expressed in g per 100 g sample. No large differences in true protein digestibility, biological value and net protein utilisation were observed between HP and NP genotypes. True protein digestibility was significantly increased by cooking in both whole-seed and dhal samples. The values for utilisable protein were considerably higher in high-protein genotypes, suggesting their superiority from the nutritional point of view.     

Cooking characteristics,chemical composition and protein quality of newly developed genotypes of pigeonpea (Cajanus cajan L)

Eight newly developed pigeonpea genotypes (ICPL 87, ICPL 151, ICPL 270, ICPL 366, ICPL 87051, ICPL 87063, ICPL 87067, and ICPV 1), and the two controls (BDN 2 and C 11) were analysed for cooking quality parameters and chemical composition, including amino acids and minerals. Protein quality was evaluated by determining the true protein digestibility, biological value, net protein utilisation (NPU), and utilisable protein. These genotypes differed significantly (P < 0–01) in the dhal cooking time. Sensory properties of dhal of these genotypes were found to be within the acceptable range, even though there were considerable differences among genotypes. Dhal protein, calcium, magnesium, zinc, and iron contents of these genotypes showed noticeable differences. Calcium content of ICPL 87067 was the highest (85-6 mg per 100 g) and of ICPL 87 the lowest (54-4 mg per 100 g) indicating large differences among the newly developed genotypes. No noticeable differences in sulphur-containing amino acids of these genotypes were observed. NPU was the highest (65–4%) for ICPL 366 and the lowest (56–6%) for ICPL 270 and ICPL 87067 indicating significant (P < 0–01) differences among genotypes studied.     

Physical and chemical analyses of pigeonpea (Cajanus cajan) cultivars and F1 crosses

The weight of ‘dhal’ (the edible part of the seed) from 100 whole seeds, and the hull, protein, fat, starch and soluble carbohydrate contents of 12 pigeonpea (Cajanus cajan) cultivars and the F₁ crosses were determined. The mean values for cultivars and the F₁ crosses differed in 100-seed wt, hull content (%) and protein and starch contents. Whereas 100-seed wt showed a high positive correlation with the weight of dhal, its correlation was significantly negative with hull content (%) in cultivars and protein content in the F₁ crosses.     

Methods for the estimation of protein in pigeonpea [Cajanus cajan (L.) Millsp.] and the relationship between whole grain and dhal protein contents

Protein determinations of 172 grain and dhal (decorticated dry split seed) pigeonpea samples were carried out using three methods: (a) micro-Kjeldahl (MKJ), (b) colorimetric estimation of NH₄+ with phenol hypochlorite reagents using the Technicon Auto-Analyser (TAA), and (c) dye-binding capacity (DBC) method using Acid Orange 12 dye. Protein percentages determined by the TAA and MKJ methods were highly correlated for whole-grain (0.948**) and dhal (0.967**) samples. The DBC method gave reliable results for dhal samples only. In the DBC procedure, higher protein percentages were recorded with smaller flour particles and longer mixing time, but different temperatures and durations of heating had no effect. Positive and highly significant correlations were obtained between the protein values of whole-grain and dhal samples in all the methods. Small grains gave a lower correlation between whole-grain and dhal protein content due to the observed negative correlation between grain size and percentage of seed-coat.     

In vitro Digestibility of Starch from Native and Germinated Pigeon Pea (Cajanus cajan L.)

The in vitro digestibility of native and germinated pigeon pea starches both in raw and cooked forms were investigated. The rate of digestibility (glucoamylase) was different for the two raw starches. There was a preferential utilization of low molecular weight ‘amyloses’ in the germinated samples, during in vitro enzymatic digestion of the raw granule. On acid hydrolyses, germinated samples produced lower molecular weight fragments than did raw starch, though the rate of reducing sugar released was not different. It may therefore be concluded that the size of the „amylopectin”︁ molecule is smaller in germinated starch. The easy availability of low molecular weight „amyloses”︁ may also influence the greater susceptibility of germinated starches to amylolysis even after cooking.     

Nutritional Quality of Vegetable Pigeonpeas [Cajanus cajan (L.) Mill sp.]: Mineral and Trace Elements

Mineral and trace elements of green and mature seed of pigeonpea genotypes were determined. Among the genotypes tested a considerable variation was observed in phosphorus, potassium and calcium of both green and mature seeds whereas the variation was small for magnesium. When consumed, green seeds are a richer source of iron, copper and zinc on a dry matter basis than the mature seed whereas there was a reverse trend for manganese. The calcium content of mature seed was significantly higher than green seed and this was attributed to the seed coat content of the mature seed.     

Proteinase inhibitors of redgram (Cajanus cajan)

Proteinase inhibitory activity of 35 varieties of redgram (Cajanus cujun L) was determined. Chymotrypsin inhibitory activity was more pronounced than trypsin inhibitory activity in all redgram varieties tested. Both trypsin and chymotrypsin inhibitory activities were found to be markedly reduced on germination.     

Effect of bicarbonate soaking on dehusking efficiency and composition of pigeon pea (Cajanus cajan L.) seeds and dhal

Soaking pigeon pea seeds in 6% sodium bicarbonate solution for 1 h, followed by oven-drying to 10% moisture improved dehusking efficiency from 66% in untreated seeds, or 71% in water-soaked seeds similarly dried, to 94% yield of dhal. Treatment reduced gum and pectin content, increased enzyme activity, but caused losses in protein and starch content of the dhal.     

Storage of mung bean (Vigna radiata [L.] Wilczek) and pigeonpea grains (Cajanus cajan [L.] Millsp) in hermetic triple-layer bags stops losses caused by Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Dry mung bean and pigeonpea grains that had sustained some insect damage but fumigated before the start of the experiment were stored in triple-layer hermetic bags (Purdue Improved Crop Storage (PICS™ bags) or woven polypropylene (PP) bags for 6 months. Some of the bags were artificially infested with cowpea bruchid Callosobruchus maculatus (F.) (PICS1, PP1) while others were not (PICS0, PP0). In an additional trial, PP bags containing the grains were treated with Actellic Super^® dust before being artificially infested (PP1Ac). Moisture content, live adult C. maculatus count, grain damage, weight loss, and seed germination were determined on a monthly basis. At six months, moisture contents of grain stored in PICS and PP bags remained below 12%. Storage in PICS bags halted multiplication of C. maculatus, and the initial damage level and weight of grains did not change. Conversely, in the PP bags, C. maculatus populations increased massively and seed damage reached 71.8 ± 1.9%, 76.9 ± 0.4%, and 60.3 ± 0.6% corresponding to weight losses of 14.5 ± 0.1%, 16.5 ± 0.2% and 12.5 ± 0.1% in PP0, PP1 and PP1Ac, respectively, in mung beans. With the pigeonpeas, seed damage reached 55.1 ± 0.6%, 95.7 ± 0.4% and 75.8 ± 0.9%, corresponding to weight losses of 13.0% ± 0.3%, 26.2 ± 0.2% and 13.5 ± 0.1%, in PP0, PP1 and PP1Ac, respectively. PICS bags are an effective tool for preserving mung beans and pigeonpeas against C. maculatus attack, and their performance is superior to that of Actellic Super^® dust.     

Nutritional Quality of Vegetable Pigeonpeas [Cajanus cajan (L.) Millsp.]: Dry Matter Accumulation, Carbohydrates and Proteins

Since average dry matter accumulation of green pigeonpea seeds intended for use as a vegetable was 65.6% of the total in matured seeds, green seeds were collected prior to physiological maturity. Green seed contained less starch and more dietary fiber than did mature seed. Flatulence causing oligosaccharides were present in a lower amount in green seed. Trypsin inhibitor activity (TIA) was more in mature seed whereas green and mature seed differed little in chymotrypsin inhibitor activity (CIA). The mean value for in vitro protein digestibility (IVPD) of green seed was more than that of mature seed. The green seed had a greater amount of tryptophan and threonine and the sulphur containing amino acids, methionine and cystine. It is concluded that the green seeds of pigeonpea genotypes are nutritionally better than their mature seeds.     

Physicochemical properties and antioxidant activity of colored peppers (Capsicum annuum L.)

Food Science and Biotechnology - Peppers are spices consumed all around the world. This study evaluated the physicochemical properties and antioxidant activities of red, orange, yellow, green, and...     

Physicochemical and functional properties of whole legume flour

The physicochemical, functional and pasting properties of whole flours from pinto bean, lima bean, red kidney bean, black bean, navy bean, small red bean, black eye bean, mung bean, lentil and chickpea were investigated. Significant differences in physicochemical characteristics and functional properties were observed (P < 0.05). Bulk densities, water absorption indices, water solubility indices, oil absorption capacities, emulsion activities, and emulsion stabilities ranged from 0.543 g/mL to 0.816 g/mL, 4.09 g/g to 6.13 g/g, 19.44 g/100 g to 29.14 g/100 g, 0.93 g/g to 1.38 g/g, 61.14%–92.20%, and 84.15%–96.90%, respectively. Phaseolus legume flour exhibited higher water absorption capacity, oil absorption capacity, emulsion activity, and emulsion stability compared with other kinds of legume flour. Pasting properties were significantly different (P < 0.05). Pasting temperatures and the peak, final, and setback viscosities of the flours ranged from 73.2 °C to 83.0 °C, 96.2 RVU to 216.8 RVU, 118.5 RVU to 243.8 RVU, and 28.3 RVU to 103.2 RVU, respectively.     

Physicochemical properties of paprika (Capsicum annuum L.) dehydrated with red algae extract

Paprika (Capsicum annuum L.) slices were dehydrated with red algae extract (RAE) at a concentration of 30%(w/w) and compared with hot-air dried samples in terms of rehydration ratio, total carotenoid content, ascorbic acid, microstructure, and color. The rehydration ratios of RAE-treated samples were higher than those of hot-air dried samples. The total carotenoid contents of RAE-treated samples were similar to those of fresh paprika and higher than those of hot-air dried paprika. In addition, the ascorbic acid contents of RAE-treated samples were higher and the microstructures of RAE-treated samples were superior to those of hot-air dried samples in terms of cellular matrix. The colors of RAE-treated samples were similar to that of fresh paprika and better than those of hot-air dried samples. These results suggest that paprika can be dehydrated with RAE without loss of functional components or quality.     

Physicochemical characteristics and functional properties of grape (Vitis vinifera L.) seeds protein

The amino acid composition, physicochemical and functional properties of grape (Vitis vinifera L.) seeds protein (GSP) were evaluated and compared with those of soybean protein isolate (SPI). Amino acid analyses of GSP revealed high levels of glutamic/glutamine, glycine and aspartic/asparagines. SDS‐PAGE analysis demonstrated that globulin was the major protein component in GSP, whose subunit molecular weights were mainly varied from 25.5 to 40.0 kDa. The isoelectric pH of GSP was found to be at the acidic pH of around 3.8. At all the pHs tested except pH 2.0, no significant changes of GSP secondary structure were observed. GSP exhibited beneficial functional properties such as preferable solubility and emulsifying activity, while the foaming properties and water holding capacity were relatively poor compared to SPI. It could then be employed to soup, sauce, beverage or meat product for improving nutritional and sensory quality of these foods at appropriate pHs.     

Physicochemical properties and silicon content in wheat flour treated with diatomaceous earth and conventionally stored

This study was done to evaluate the physicochemical properties and to quantify the residual silicon in flour from wheat grains treated with different dosages of DE and stored in a conventional system for 180 days. Samples containing 10.0 kg of wheat grain were treated with 0.00, 2.00 and 4.00 g kg⁻¹ of DE and then homogenized and stored in cotton bags at 22 °C and 70 ± 5 g 100 g⁻¹ relative humidity. Physicochemical analyses were carried out at 0, 60, 120 and 180 days of storage. The experiment was conducted in a randomized design with a factorial 3 × 4 arrangement (three doses of DE × four storage periods), totaling 12 treatments, with three replicates for each treatment. The wheat flour samples were digested and the silicon residue quantification was conducted through colorimetry. The wheat treated with DE presented a lower test weight compared with control, +b^∗ chromaticity coordinate for color and increased ash content and L^∗. The physicochemical changes in the grain and wheat flour were proportional to the amount of DE applied.     

Selected functional properties of sesame (Sesamum indicum L.) flour and two protein isolates

Functional properties of sesame flour and protein isolates have been compared with those of some commercial soya products. The sesame products showed better fat absorption, poorer water absorption and overall lower bulk densities than soya products. Emulsifying activities and stabilities were generally lower than soya products. Destabilisation of the emulsion in the presence of NaCl was noted. Sesame products showed better foam expansion, and comparable foam stability and strength to corresponding soya products. Addition of sugar to sesame whips reduced foam expansion and increased foam stability. Acid, neutral and alkaline sesame whips showed distinct whipping properties depending on the product used. Sesame whips resembling those of egg-white could be obtained. The sesame isolate prepared by alkaline extraction was superior to that prepared by salt extraction in terms of their pH-solubility profiles.     

Physicochemical properties of pectins from okra (Abelmoschus esculentus (L.) Moench)

Okra pectin obtained by hot buffer extraction (HBSS) consists of an unusual pectic rhamnogalacturonan I structure in which acetyl groups and alpha galactose residues are substituted on rhamnose residues within the backbone. The okra Chelating agent Soluble Solids (CHSS) pectin consists of slightly different structures since relatively more homogalacturonan is present within the macromolecule and the rhamnogalacturonan I segments carry slightly longer side chains. The rheological properties of both okra pectins were examined under various conditions in order to understand the unusual slimy behaviour of okra pectins. The viscosity of the okra HBSS pectin was 5–8 times higher than the viscosity of the okra CHSS pectin. The okra HBSS pectin showed an elastic behaviour (G′ > G″) over a wide range of frequencies (10⁻¹–10 Hz), at a strain of 10%, while okra CHSS and saponified okra HBSS/CHSS pectin showed predominantly viscous responses (G′ < G″) over the same frequency range. The results suggest that the structural variation within the okra pectins greatly affect their rheological behaviour and it is suggested that acetylation of the pectin plays an important role through hydrophobic associations. Dynamic light scattering was used to study the association behaviour of both okra pectins at low concentration (0.001–0.1% w/w). Results showed that the saponified okra pectins did not exhibit a tendency to aggregate in the concentration range studied, whereas both non saponified samples showed a substantial degree of association. These results suggest that the unusual slimy behaviour of the non saponified samples may be related to the tendency of these pectins to associate, driven by hydrophobic interactions.