Pulse proteins: secondary structure, functionality and applications.

Pulses are the second most important source of food for humans after cereals. They hold an important position in human nutrition. They are rich source of proteins, complex carbohydrates, essential vitamins, minerals and phytochemicals and are low in lipids. Pulses are also considered the most suitable for preparing protein ingredients (concentrates and isolates) because of their high protein content, wide acceptability and low cost. In addition, pulse proteins exhibit functional properties (foaming and emulsification, water and fat absorption and gelation) as well as nutraceutical/health benefiting-properties which makes them healthier and low cost alternative to conventional protein sources like soy, wheat and animals. Proteins from different pulses (beans, peas, lentils, cowpeas, chickpeas, pigeon peas, etc.) differ in their composition and structure hence for finished product suitability. Therefore, this article aimed to review composition, structure-function relationship and current applications of different pulse proteins in the food industry.

Effect of chickpea and spinach on extrusion behavior of corn grit.

The present work was carried out to see the effect of blending of corn grit (CG) with varying levels of chickpea grit (CP 0-100%) and spinach leaf powder (SP 0-6%) on the characteristics [color, expansion, density, hardness, water absorption index, total phenolic content (TPC), antioxidant activity (AOA; as DPPH and ABTS free radical scavenging activities)] and sensory properties of extrudates. CP and SP were rich in proteins and minerals (Cu, Fe, Zn, Mg, Ca, K and Na). Their blending significantly influenced the physicochemical and antioxidant properties of CG extrudates. TPC and AOA of extrudates increased with the increased incorporation of CP and SP, though specific mechanical energy and extrudate expansion, generally, decreased while density and hardness increased. Sensory analysis revealed that CP and SP at incorporation levels of 25% and 4%, respectively could be blended with CG for making highly acceptable antioxidant-rich expanded snack.

Bioactive constituents in pulses and their health benefits.

Pulses are good sources of bioactive compounds such as polyphenols, phytosterols and non-digestible carbohydrates that play important physiological as well as metabolic roles. These compounds vary in concentration amongst different pulse species and varieties. Pulse seed coats are rich in water-insoluble fibres and polyphenols (having high antioxidant activities), while cotyledons contain higher soluble fibres, oligosaccharides, slowly digestible and resistant starch content. Ferulic acid is the most abundant phenolic acid present in pulses, while flavonol glycosides, anthocyanins and tannins are responsible for the seed coat colour. Sitosterol (most abundant), stigmasterol, and campesterol are the major phytosterols present in pulses. Pulse fibres, resistant starch and oligosaccharides function as probiotics and possess several other health benefits such as anti-inflammatory, anti-tumour, and reduce glucose as well as lipid levels. Beans and peas contain higher amounts of oligosaccharides than other pulses. Processing methods affect resistant starch, polyphenol composition and generally increase antioxidant activities of different pulses. In this review, the current information on pulse polyphenols, phytosterols, resistant starch, dietary fibre, oligosaccharides, antioxidant and associated health benefits are discussed.

Composition, bioactive compounds and antioxidant activity of common Indian fruits and vegetables.

The present work was undertaken to evaluate the chemical composition (proximate, minerals and dietary fibre), colour parameters, antioxidant activity and polyphenol profiles of different fruits (pomegranate, kinnow, mango, banana, jambolan, grapes and sapodilla) and vegetables (beetroot, brinjal, orange carrot, bitter gourd, mentha and spinach). The amount of insoluble dietary fibre was higher than soluble dietary fibre for all fruits and vegetables. Vegetables showed superior mineral composition (higher amounts of K, Ca and Fe) as compared to fruits. Total phenolic content (TPC) and antioxidant activity (ABTS and DPPH) ranged from 354.9 to 1639.7 mg GAE/100 g, 2.6 to 5.5 and 3.0 to 6.3 mM TE/g, respectively for different fruits, while it ranged from 179.3 to 1028.6 mg GAE/100 g, 2.1 to 4.7 and 2.0 to 5.0 mM TE/g, respectively for different vegetables. Gallic acid, protocatechuic acid, catechin, caffeic acid, ferulic acid, sinapic acid, quercetin, resveratrol and kaempferol were detected and quantified in different fruits and vegetables. The results highlighted that fruit peels could be used as valuable sources of minerals and polyphenols having high antioxidant activity.

Physicochemical and rheological properties of starch and flour from different durum wheat varieties and their relationships with noodle quality.

Starch and flour properties of different Indian durum wheat varieties were evaluated and related to noodle-making properties. Flours were evaluated for pasting properties, protein characteristics (extractable as well as unextractable monomeric and polymeric proteins) and dough rheology (farinographic properties), while starches were evaluated for granule size, thermal, pasting, and rheological properties. Flour peak and final viscosities related negatively to the proportion of monomeric proteins but positively to that of polymeric proteins whereas opposite relations were observed for dough rheological properties (dough-development time and stability). Starches from varieties with higher proportion of large granules showed the presence of less stable amylose-lipids and had more swelling power, peak viscosity and breakdown viscosity than those with greater proportion of small granules. Noodle-cooking time related positively to the proportion of monomeric proteins and starch gelatinization temperatures but negatively to that of polymeric proteins and amylose content. Varieties with more proteins resulted in firmer noodles. Noodle-cohesiveness related positively to the proportion of polymeric proteins and amylose-lipids complexes whereas springiness correlated negatively to amylose content and retrogradation tendency of starches.

Effect of guar gum and xanthan gum on pasting and noodle-making properties of potato, corn and mung bean starches.

The effect of xanthan and guar-gum on pasting and noodle-making properties of potato, corn and mung bean starches was studied. Mung bean starch showed the highest amylose content (43.4 %) followed by potato (23.2 %) and corn starch (15.5 %). Potato starch showed the highest swelling power (19.0 g/g) and solubility index (17.5 %) and exhibited the highest paste viscosities. Addition of both gums improved peak viscosity, hot paste viscosity and final viscosity for mung and corn starches; while for potato starch, guar gum increased peak and final viscosities and decreased hot paste viscosity while xanthan gum increased hot paste and final viscosities and decreased peak viscosity. The noodles made from mung bean starch showed the most desirable characteristics in terms of the lowest-cooking loss and adhesiveness. The gums increased noodle cooking time and decreased cooking loss, firmness and cohesiveness.

Effect of banana flour, screw speed and temperature on extrusion behaviour of corn extrudates.

Effect of extrusion parameters (banana flour, screw speed, extrusion temperature) on extrusion behaviour of corn grit extrudates were studied. Second order quadratic equations for extrusion properties as function of banana flour (BF), screwspeed (SS) and extrusion temperature (ET) were computed. BF had predominant effect on the Hunter color (L*, a*, b*) parameters of the extrudates. Addition of BF resulted in corn extrudates with higher L* and lower a* and b* values. Higher ET resulted in dark colored extrudates with lower L* and a* value. Higher SS enhanced the lightness of the extrudates. Expansion of the extrudates increased with increase in the level of BF and ET. WAI of the extrudates decreased with BF whereas increased with SS. However, reversed effect of BF and SS on WSI was observed. Flextural strength of the extrudates increased with increase in SS followed by BF and ET. The addition of BF and higher ET resulted in extrudates with higher oil uptake.

Colour, composition, digestibility, functionality and pasting properties of diverse kidney beans (Phaseolus vulgaris) flours.

The present work evaluated nine diverse kidney bean accessions for colour, composition, digestibility, protein profile, starch crystallinity, techno-functional properties, pasting properties and microstructure with the objective of identifying key attributes affecting their digestibility and functionality. The accessions exhibited dry matter digestibility, resistant starch (RS) content, water absorption capacity, fat absorption capacity, emulsifying activity index (EAI), foaming capacity (FC) and foam stability (FS) of 14.6-47.2%, 32.0-50.5%, 1.7-2.7 g/g, 1.4-1.7 g/g, 50.1-70.1 m2/g, 70.8-98.3% and 82.4-91.3%, respectively. Starch-lipid complexes (SLC), proteins and non-starch carbohydrates contributed to lower starch and dry matter-digestibility. Principal component analysis revealed positive relation of emulsification, foaming and water absorption capacity with proteins, starch, RS and ash-content while negative with crystallinity and amount of lipids, non-starch carbohydrates and digestible starch. Hydration ability of proteins promoted foaming whereas flour with lower vicilins level was less surface active and exhibited the lowest EAI, FC and FS. Pasting temperature related positively with SLC, while average starch granule size was in strong positive relationship with RS content, peak viscosity and breakdown viscosity. The results could be useful for enhanced utilization of kidney beans in different foods.

Effect of degree of milling on physicochemical, structural, pasting and cooking properties of short and long grain Indica rice cultivars.

The effects of degree of milling (DOM) between 0 and 8% on physico-chemical, structural, pasting and cooking properties of short and long grain Indica rice cultivars were studied. Ash, protein, lipids and minerals decreased while blue value and crystallinity increased with increase in DOM. The colour parameters (a∗, b∗) and cooking time (CT) decreased while L∗(lightness) increased with increase in DOM. Elongation ratio (ER), gruel solid loss (GSL), length/breadth (L/B) and paste viscosities during cooking increased with increase in DOM. Short grain rice contained lower ash, protein, lipids, Mn, K, Ca, CT and GSL than long grain while the later showed higher crystallinity, Mn, P, K, Ca and ER. Paste and dough characteristics measured using Rheometer and Mixolab, respectively correlated well and differed with cultivar and DOM. Short and long grain cultivars showed variation in loss of different chemical constituents during varied DOM causing variation in cooking characteristics.

Physicochemical, pasting, and functional properties of amaranth seed flours: effects of lipids removal.

UNLABELLED: The present work was carried out to evaluate physicochemical (composition, hunter color, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis [SDS-PAGE]), pasting, and functional properties (foaming, emulsification, water, and fat absorption capacity) of amaranth full-fat flours from 6 lines/cultivars (AFs), and to see the effects of lipid removal/defatting on these properties. Protein, ash, and lipid content of AFs ranged between 12.5% to 15.2%, 3.0% to 3.5%, and 7.1% to 8.0%, respectively. The flours showed a number of bands between 97 and 7 kDa, with main subunits of approximately 58, 37, 33, 31, 23, and 16 kDa in the SDS-PAGE profiles. The protein content and L* value increased, while b* values decreased following defatting for most of the lines/cultivars. The defatted flours (DAFs) had higher final viscosity and stability (lower breakdown viscosity) as compared to counterpart AFs. The protein profiling of the flours was not affected with the lipid removal/defatting. However, water absorption capacity and foam stability of the flours improved upon defatting. Principal component analysis revealed that pasting temperature was positively related to lipid content, while breakdown viscosity was negatively related to protein content. Foaming properties (capacity and stability) showed negative relationship with lipid content, and positive with protein content, ash content, water, and fat absorption capacity. PRACTICAL APPLICATION: Amaranth grains are known to have higher amount of proteins and lipids than cereals. Amaranth lipids are rich in unsaturated fatty acids, which are prone to oxidative rancidity. Removal of lipids or defatting of flours may be carried out to enhance product shelf life by preventing undesirable oxidative chain reactions. Therefore, this research was undertaken to see the effects of defatting on the functional properties of amaranth flours. The defatting was a value addition process as it improved the functional properties of the flours.