Effect of several pre-treatments on the physical characteristics of dehulled fraction of pigeon pea (Cajanus cajan L)

Processing of pigeon pea ( Cajanus cajan L.) involves pre-treatment in order to loosen the hull, followed by dehulling. In this study, different pre-treatments were investigated and different parameters such as moisture gain, temperature change during different steps of processing and dehulled fractions were measured and analysed. The highest temperature observed after pre-treatment was 92.1 °C and the lowest was 24.6 °C, for hydrothermal and wet methods, respectively. It was found that the hydrothermally treated pigeon pea gave the highest amount of dehulled grains, followed by the dry method. There were higher amounts of brokens (17.6 g) in case of wet method and lower (6.2 g) in case of dry method. Hydrothermal treatment was found suitable when compared with other pre-treatments. Cooked samples were tested against a 9-point hedonic scale and hydrothermally treated samples were found to have better acceptability.     

Effects of NaCl,ionic strength and pH on the foaming and gelation of pigeon pea (Cajanus cajan) protein concentrates

Studies were carried out on the effects of pH, ionic strength, sample concentration and added salt (NaCl) concentration on two hydrodynamic properties — gelation capacity and foaming properties of pigeon pea protein concentrates. Results indicate that the protein concentrate has a good gelation capacity with a least gelation concentration of 6% (w/v). Using the least concentration endpoint (LCE) as an index of gelating ability, the gelation capacity of the flour improved in the presence of moderate NaCl concentration and low ionic strength. Acidic and neutral pH also enhanced gelation while alkaline pH decreased it. The foaming capacity of the flour could be improved in a medium of low ionic strength and by increasing the concentration of protein sample as well as by a moderate concentration (0.25% w/v) of NaCl. Better foaming capacity was observed in the acidic region than in the alkaline region. Foams were also observed to be more stable as concentration of NaCl, concentration of protein concentrate and ionic strength increased.     

The physico-functional characteristics of starches from cowpea (Vigna unguiculata), pigeon pea (Cajanus cajan) and yambean (Sphenostylis stenocarpa)

Starches fractionated from cowpea (Vigna unguiculata, Ife Brown), pigeon pea (Cajanus cajan, Cita II) and yambean (Sphenostylis stenocarpa) were comparatively studied for physical and functional properties, including granule morphology, granule sizes, water absorption capacity, water–oil absorption index, swelling capacity, ionic property, bulk density and amylographic viscosities. The three legume starch granules range in diameter size from 5–57.5 μm. The water absorption capacities of all the starches were generally low at room temperature up to 70°C. Pigeon pea starch was the least susceptible to swelling while the cowpea starch was the most susceptible. The starches displayed non-ionic character, low water activity, high bulk density, water and oil absorption capacities and type C Brabender visco-amylograms at 6.2% starch-water slurry (on dry wt basis). ©     

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.     

In vitro digestibility,structural and functional properties of starch from pigeon pea (Cajanus cajan) cultivars grown in India

Starches isolated from two pigeon pea cultivars (AL-15 and AL-201) were evaluated for their in vitro digestibility, structural and functional properties. Both the cultivars exhibited a characteristic C-type diffraction pattern with relative crystallinity values of 31.9% and 34.2%, for AL-15 and AL-201, respectively. The structural characterization obtained using high performance size exclusion column chromatography revealed that molecular weight of amylopectin and amylose was higher for AL-201 (396 and 3.92 × 10⁶ g/mol, respectively) in comparison to AL-15 starch (354 and 3.31 × 10⁶ g/mol, respectively). AL-201 exhibited higher values for transition temperatures, enthalpy of gelatinization, pasting temperature and percentage retrogradation in comparison to AL-15 starch. Slowly digestible starch, readily digestible starch and resistant starch contents of AL-15 and AL-201 cultivars were observed to be 31.0, 8.1 and 60.9% and 29.6, 5.2 and 65.2%, respectively. The hydrolysis index and RS values indicated that pigeon pea starches were highly resistant to digestion.     

Hydroxypropylation of pigeon pea (Cajanus cajan) starch: Preparation, functional characterizations and enzymatic digestibility

Hydroxypropyl starch derivatives were prepared from pigeon pea starch (NPPS) which is an unconventional starch source. Functional parameters and characterization of both native and modified starches were carried out. The starch granules appeared oval or elliptical in shape with sizes ranging from 7 to 40 μm in width and 10 − 30 μm in length. Hydroxypropylation did not alter the shape of the starch granules in a pronounced way. Generally, the x-ray diffractograms of native pigeon pea starch showed the “A” pattern. However, slight reductions in the diffraction intensity of starches after modification were observed. At all temperatures studied (30-90 °C), swelling and solubility of hydroxypropylated starches were higher than the NPPS. Progressive increases in swelling capacity and solubility were observed as the molar substitution (MS) increased among the hydroxypropylated starches. Hydroxypropylation reduced starch paste turbidity on storage. Also, studies showed that syneresis reduced after hydroxypropylation. In addition, syneresis reduced as the MS of the hydroxypropyl starches increased. The results indicate that pasting temperature and peak temperature reduced after modification but peak viscosity increased in hydroxypropylated starch derivatives compared with the native starch. Setback reduced in hydroxypropylated starches compared with the native starch. Enthalpy of gelatinization and percentage retrogradation reduced after hydroxypropylation and progressive reductions were observed as the MS increased among the starch derivatives. Hydroxypropylation increased enzymatic digestibility.     

Starch enzymatic hydrolysis,structural, thermal and rheological properties of pigeon pea (Cajanus cajan) and dolichos bean (Dolichos lab-lab) legume starches

Cajanus Cajans and Dolichos lab-lab legume starches from Argentine cultivars were investigated under a technological and nutritional point of view. Their physico-chemical, structural, thermal and the rheological properties of their gels were evaluated. Rice (RS) and potato (PS) starches were included as references. In vitro digestibility from Englyst method was also evaluated. Legume starches had the highest amylose content and the most stable chemical structure. Their rapidly digestible starch and starch digestibility rate index were very low, similar to PS, and fivefold lower than RS. They had a much higher slowly digestible starch content than PS. Legume starches showed the highest gel stability versus heating and stirring and an intermedium pasting temperature between RS and PS. They formed viscoelastic gels at 6% concentration with stronger elastic-like behaviour and higher yield stress than references. Our results indicate these legumes represent an efficient starch source to provide tailor-made properties to food/industrial applications.     

Optimization of process parameters for the development of a cheese analogue from pigeon pea (Cajanus cajan) and soy milk using response surface methodology

Response surface methodology was used to optimize starter culture concentration (3–7%), pigeon pea–soy solids ratio (1 : 0.3–1 : 1.1), pigeon pea–water ratio (1 : 12–1 : 9), incubation temperature (37–45C) and coagulation temperature (75–95C) in the development of a cheese analogue from pigeon pea and soy milk. Pigeon pea milk and soy milk were prepared by a hot water grinding method, followed by filtration and inoculation. Cheese analogue was obtained through coagulation of the fermented milk by boiling for 15 min, followed by filtration using double-layered muslin cloth and pressing at 1 kg/cm ² pressure for 1 h. The results showed that the total solids recovery (TSR), protein content, fat content and pH varied from 51.09–62.61%, 40.04–55.93%, 9.35–15.36% and 4.48–4.9, respectively, depending on the experimental conditions. The optimum conditions of process parameters for maximum total solids recovery were 6.0% starter culture concentration, 1 : 0.4 pigeon pea–soy solids ratio, 1 : 11 pigeon pea–water ratio, 40.5C incubation temperature and 88.5C coagulation temperature.     

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.     

Further characterisation of protease inhibitors from pigeon pea (cajanus cajan (l) millsp) seeds

Cajanus trypsin inhibitor (CTI) and Cajanus trypsin-chymotrypsin inhibitor (CTCI) previously purified from cv TAT-10 were further characterised. The modification of the inhibitors revealed the presence of lysine at the trypsin reactive site in both CTI and CTCI. Modification of tyrosine at the reactive site of CTCI did not abolish chymotrypsin inhibition suggesting the presence of leucine or phenylalanine as reported in other chymotrypsin inhibitors. CTCI did not contain tryptophan. Dissociation constants for the inhibitors with bovine trypsin were in the region of 0.69 nmol (CTCI) and 0.029 nmol (CTI). Although the protease inhibitors lost their inhibitory activity on exposure to 2-mercaptoethanol they remained attached to the enzyme. The inhibitors were not very effective against the protease from Helicoverpa armigera which is a serious field pest of Cajanus. Dissociation constants for the inhibitors with the larval enzyme were in the region of 100 nmol.     

Purification and characterisation of protease inhibitors from pigeon pea (cajanus cajan (l) millsp) seeds

Two protease inhibitors from Cajanus cajan seeds have been purified to homogeneity by trichloroacetic acid (TCA) solubilisation, ion-exchange and gel-filtration chromatography followed by preparative polyacrylamide gel electro-phoresis. One of the inhibitors, Cajanus trypsin-chymotrypsin inhibitor (CTCI), inhibits both bovine trypsin and chymotrypsin while the other, Cajanus trypsin inhibitor(CTI), inhibits only bovine trypsin. The two inhibitors contained no carbohydrate and had an isoelectric point of 6. CTCI and CTI had average molecular weights of 15000 and 10500, respectively. The purified inhibitors in solution were stable to heat at 80°C for 15 min and pH 7–10. In the pH range 3–5, 80% of the activity was retained. Autoclaving totally destroyed the inhibitor activity. CTCI had two sites for trypsin binding and one site for chymotrypsin binding while CTI had only one site for trypsin binding. The inhibitors were very specific towards mammalian serine proteases and did not inhibit other proteases or serine proteases of bacterial origin.     

Effect of different treatments on the microstructure and functional and pasting properties of pigeon pea (Cajanus cajan L.), dolichos bean (Dolichos lablab L.) and jack bean (Canavalia ensiformis) flours from the north‐east Argentina

The effect of germination (G; 5 days), soaking‐cooking (SC; 6 h–20 min, 6 h–40 min, 6 h–60 min) and microwave (M; 50%, 70%, 100%) treatments on pigeon pea (PP), dolichos bean (DB) and jack bean (JB) seeds was studied. Microstructure of seeds and functional (protein solubility, water‐holding capacity, oil‐holding capacity, emulsion stability) and pasting properties of flours were determined. Germination and microwave treatments modified the protein matrix of cotyledon cells preserving the shape of the starch granule, whereas the SC treatment (6 h–60 min) affected both. The soaking‐cooking is the most influential treatment on the functional properties of PP, DB and JB flours, as increased water absorption capacity (73–96%), decreased protein solubility (>80%) and the tendency to retrogradation of amylose (69–85%) also improved emulsion stability.     

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.     

A Histological Basis for 'Hard-To-Cook' Phenomenon in Red Gram (Cajanus cajan) Cultivars

Sections of cotyledons (dhals) and leached starch granules in red gram (Cajanus cajan), were examined microscopically. The average expansion ratios of good cooking (GCD) and poor cooking (PCD) dhals were 1.8 and 1.4 for cotyledons, 2.4 and 2.0 for cells at 30 min cooking, and 6.5 and 5.5 for starch granules at 6 min cooking, respectively. Cells and starch granules of GCD dispersed freely and quickly into the medium while those of PCD tended to disperse slowly and remain in clusters. The variation in expansion, separation and clustering properties of cells and starch granules during cooking caused cookability differences of red gram cultivars.     

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.