Flaking of millets and its impact on bioactivity, pasting, digestibility, structural and thermal properties.

Five different millets (foxtail, little, barnyard, kodo and browntop) with and without sprouting were subjected to flaking. Phytic acid and phenolic content tends to decrease significantly, whereas antioxidant activity increased up to 77.32% on flaking of millets. A significant decrease in peak and final viscosity was observed in millet flakes. A-type diffraction pattern was predominant for unsprouted millets whereas the flaked millets showed V-type crystallinity. The protein digestibility significantly increased up to 37.77% in flakes made from sprouted millets. The mineral bioavailability upon flaking of millets increased, especially Ca (88.22% for little), Fe (43.04% for barnyard) and Zn (61.77% for kodo), which is attributed to the reduction in phytic acid. Flaking, however, led to an increase in rapidly and slowly digestible starch with a corresponding decrease in resistant starch. Among the unsprouted and sprouted millet flakes, foxtail received the highest sensory scores for overall acceptability.

Modifying the dough mixing behavior, protein & starch digestibility and antinutritional profile of minor millets by sprouting.

The objective of this study was to evaluate the impact of sprouting (0, 12, 24, 36, 48 hr) on enzyme activity, protein solubility, dough mixing behavior, anti-nutritional components and in vitro starch and protein digestibility of minor millets. Sprouting decreased starch, fat, protein and ash contents while the dietary fiber content, amylase and protease activity significantly (p < 0.05) increased. Sprouting promoted a significant (p < 0.05) decrease in anti-nutritonal components like phytic acid and condensed tannin. The protein solubility enhanced that also resulted in improved protein digestibility (in vitro) of sprouted millets. Sprouting exerted a significant (p < 0.05) effect on mixolab dough rheology indicating a decrease in dough consistency (C1), peak and final viscosity whilst protein weakening and breakdown increased (p < 0.05). This process produced an increase in free glucose thereby improving rapidly digestible starch and increasing glycemic index. A significant (p < 0.05) reduction in resistant starch along with slowly digestible starch was promoted during sprouting. In conclusion, sprouting provides millet flours with modified nutritional quality and better technofunctional properties than the raw flours that may suggest their potential utilization in complementary food formulations and baked products.

Modulation in quality attributes of dough and starch digestibility of unleavened flat bread on replacing wheat flour with different minor millet flours.

The dough characteristics and flat bread quality parameters were studied on replacing a part of wheat flour with different minor millets (finger, foxtail, barnyard, kodo, little, proso) in the proportion 3:1. The dietary fiber and phytic acid increased while damaged starch decreased on replacing wheat flour with millet flour. The millet flours lowered water absorption and dough stability however protein weakening, gelatinization temperature and peak viscosity during heating increased. Flat breads prepared from wheat millet composite flour displayed more shrinkage and bake loss and reduced puffing and starch retrogradation. Rapidly digestible starch and glycemic index lowered while slowly digestible and resistant starch increased significantly (p < 0.05) as a consequence of millet flour addition to wheat flour. Millets as whole flour can be utilized in formulation of food products having higher neutraceutical value by replacing a part of wheat flour with millet flours.

Influence of nutritional and antinutritional components on dough rheology and in vitro protein & starch digestibility of minor millets.

The nutritional and antinutritional components of minor millets were correlated with mixolab dough mixing behavior and in vitro protein and starch digestibility. Total arabinoxylan (r = -0.53, p < 0.05) and dietary fiber (r = -0.66, p < 0.05) content significantly (p < 0.05) increased protein weakening. Peak viscosity negatively correlated with phenolic (r = -0.55, p < 0.05) content. The dietary fiber and phenolics suppressed retrogradation. Protein digestibility negatively correlated with tannin (r = -0.70, p < 0.05), phytic acid (r = -0.69, p < 0.05), phenolics (r = -0.79, p < 0.05), flavonoids (r = -0.72, p < 0.05) and total dietary fiber content (r = -0.84, p < 0.05). A positive correlation of resistant starch (RS) with total dietary fiber (r = 0.85, p < 0.05), phenolics (r = 0.89, p < 0.05), flavonoids (r = 0.83, p < 0.05), phytic acid (r = 0.43, p < 0.05) and tannin content (r = 0.79, p < 0.05) was observed. Millets predicted lower glycemic index than wheat and it was found to be negatively associated with the RS (r = -0.96, p < 0.05) and total dietary fiber content (r = -0.89, p < 0.05) and positively correlated (r = 0.98, p < 0.05) with rapidly digestible starch. The millets may be diversified for personalized nutrition and development of functional food.

Utilization of flour from rice brokens in wheat flour chapatti: evaluation of dough rheology, starch digestibility, glycemic index and retrogradation behavior.

Broken rice, a byproduct of the rice milling industry was utilized at different levels to evaluate unleavened flat bread (chapatti) making properties of whole wheat flour. Chapattis were prepared by replacing whole wheat flour with broken rice flour up to 50% level. Mixolab studies revealed that incorporation of rice flour lowered dough development time and dough stability of whole wheat flour up to 23.49% and 78.33%, respectively. Lower retrogradation was observed in whole wheat rice flour blends as revealed from soluble starch/amylose. A positive correlation of mixolab retrogradation was observed with soluble starch and soluble amylose. Whole wheat flour chapatti (fresh and retrograded) containing different level of rice flour were also evaluated for glycemic index (GI), rapidly digestible starch (RDS) and slowly digestible starch (SDS). Chapattis containing rice flour demonstrated higher GI and RDS but lower SDS. RDS correlated positively with GI. Chapattis from the whole wheat rice flour blends had good consumer acceptability.

Relationship of Mixolab characteristics with protein, pasting, dynamic and empirical rheological characteristics of flours from Indian wheat varieties with diverse grain hardness.

Mixolab properties of different Indian extraordinarily soft (Ex-SW), hard (HW) and medium hard (MHW) wheat varieties were evaluated and related to damaged starch content, particle size distribution, pasting, Farinographic and Mixographic properties. Water absorption (WA) of HW varieties was higher as compared to other varieties. Higher damaged starch led to more WA in HW varieties while lower in Ex-SW varieties. Unextratable polymeric protein, damaged starch and arabinoxylans were related to dough consistency. Mixolab measurement C3 (peak viscosity) and C5 (starch retrogradation) decreased with increase in grain hardness index, damaged starch content, and sodium solvent retention capacity. Dough stability (DS) and dough development time (DDT) measured by Mixolab and farinograph were significantly correlated. Mixolab parameters (C3, C4 and C5) related positively to DDT and DS while negatively to WA. HW varieties showed higher shear thinning as compared to MHW and Ex-SW varieties. C4 (hot paste stability) was lower for HW but higher for Ex-SW varieties. SuSRC was negatively related to C4 indicating that HW flours had lower starch retrogradation due to higher arabinoxylans. C3, C4 and C5 related positively to small size particles while negatively to large size particles. Slope beta (ß) measured by mixolab indicated that the speed of starch gelatinization was lower for Ex-SW varieties than MHW and HW varieties.

Influence of replacing wheat bran with barley bran on dough rheology, digestibility and retrogradation behavior of chapatti.

Refined wheat flour and hulless barley bran (from 9 different cultivars) were blended to create nine composite flours and their functionality compared with a control wheat flour. Mixolab studies revealed that replacing wheat bran with barley bran increased dough water absorption up to 71.5% and consistency at peak during heating up to 2.11Nm, and reduced starch retrogradation by 26.44%. The composite flours contained up to three-times more ß-glucan and significantly more total phenolics including flavonoids. Chapattis prepared from the composite blends had significantly more slowly digestible and resistant starches. Incorporating barley bran lowered starch retrogradation, based on more soluble starch and soluble amylose, and the starch retrogradation index correlated positively with decreases in soluble starch and soluble amylose. Total ß-glucan correlated negatively (r=-0.846, p<0.05) with starch retrogradation index, indicating that ß-glucan is associated with starch retrogradation.

Effect of incorporating finger millet in wheat flour on mixolab behavior, chapatti quality and starch digestibility.

Wheat and finger millet flour (two cultivars) were blended in the ratio (3:1) to form a composite flour and its dough properties were studied on the mixolab. The chapatti making and digestibility behavior of the composite flour was also investigated. The wheat finger millet (WFM) flour blend displayed up to 30.7% higher total phenolic content (TPC), 38.2% higher total flavonoid content (TFC) and 75.4% higher antioxidant activity (AOA) than the wheat flour. Chapattis prepared from the composite blends exhibited lower retrogradation as evident by the mixolab retrogradation index, higher values of soluble starch and soluble amylose in stored chapatti. The slowly digestible starch (SDS) correlated positively (R=0.816, p<0.05) with TPC and water absorption correlated positively (R=0.995, p<0.05) with damage starch content. The chapattis made from the composite flour had higher SDS and resistant starch (RS) values demonstrating potential as a food with functional characteristics.

Influence of non-starchy polysaccharides on barley milling behavior and evaluating bioactive composition of milled fractions.

Hulless barley cultivars grown at various altitudes were subjected to different conditioning treatments prior to roller milling. Amongst all treatments, conditioning grains to a moisture content of 14% for 30min was found to be optimum. The bran fractions displayed greater levels of non-starchy polysaccharides and bioactive components as compared to refined flour fraction. The presence of greater levels of ß-glucan in whole barley flour and bran of high altitude cultivars affected the refined flour yield inversely. Cultivars having higher total and insoluble arabinoxylans also resulted in lower flour yields (R=-0.76; R=-0.73). The damaged starch content of barley cultivars ranged between 5.1% and 8.7% which correlated positively with the content of ß-glucans (up to R=0.77) and arabinoxylans (up to R=0.80) in bran and refined flour fractions. The anthocyanin and total phenolic contents of refined flours ranged between 3.9-7.6µg/g and 1299-1607µg FAE/g and was higher for high altitude cultivars.

Starch digestibility and bioactivity of high altitude hulless barley.

This study was aimed at evaluating the effects of growth altitude (97-3500m) on the starch digestibility and bioactivity of hulless barley cultivars grown in India. All the high altitude cultivars (between 1200 and 3500m above sea level) displayed 7.5-30.8% higher levels of total ß-glucan, 39.8-68.6% higher arabinoxylan content, 11.0-60.9% higher total anthocyanin content and 16.6-43.2% higher metal chelating activity than the cultivars grown in plains (97-126m altitude). The soluble ß-glucan and arabinoxylan content of cultivars ranged from 2.0% to 2.8% and 0.08% to 0.19%. A positive correlation between slowly digestible starch (SDS) and insoluble ß-glucan and total arabinoxylan content was observed. Cultivars grown at higher altitudes exhibited higher bioactive potential and may find better utilization in nutraceutical foods.

Anti-staling effects of ß-glucan and barley flour in wheat flour chapatti.

Chapatti making behaviour of wheat flour containing barley flour (28%, 56% and 84%) or ß-glucan (1.5%, 3.0% and 4.5%) and their effect on staling of chapatti was studied. The dough water absorption increased significantly up to 76.7% and 78.3% upon incorporation of barley flour and ß-glucan, respectively. Bake loss significantly increased (up to 20%) upon incorporation of barley flour but was not significantly affected by ß-glucan. The peak (PV) and final viscosity (FV) significantly increased upon incorporation of barley flour (up to 105% and 65%), whereas incorporating ß-glucan decreased the PV and FV by 20.3% and 20.6%, respectively. The stored chapatties exhibited higher pasting viscosities compared to the fresh chapatties. Incorporation of barley flour exhibited a gradual increase in the enthalpy of gelatinisation (ΔHgel), similarly ß-glucan at 1.5% increased the ΔHgel. Retrogradation was lowered by 23.7%, 41.5% and 63.5% by barley flour and by 19.9%, 27.4% and 44.8% by ß-glucan.

Effect of incorporating hydrothermal, kilned and defatted oats on antioxidant and chapatti making properties of wheat flour.

Oats were subjected to treatments like defatting, hydrothermal cooking and kilning, milled into flour and then the control and treated flours were incorporated into wheat flour at 25% and 50% levels and chapatti making behaviour and antioxidant properties were studied. The treatments significantly affected the antioxidant properties of oats. Incorporating oat flours to wheat increased total phenolic content but lowered the antioxidant activity however both were decreased significantly upon baking. The reducing power of the oat blended flour was higher than the wheat flours and ranged from 8.0 to 15.5 µmol AAE/g and was further increased upon baking. The metal chelating activity of flour blends varied from 62.0% to 73.8% and further increased upon baking. After baking the total flavonoid content was lowered and ranged from 308 to 389 µg CE/g. The non-enzymatic browning index significantly increased up to 27.6% upon baking.

Effect of cyclodextrin glycosyl transferase [corrected] on dough rheology and bread quality from rice flour.

Gluten-free breads are usually characterized by deficient quality characteristics as compared to wheat breads. Problems related to volume and crumb texture are associated with gluten-free breads even when rice flour is used, which seems to be the best raw material for this type of bread. The potential use of cyclodextrin glycosyl transferase (CGTase) as a rice bread improver is presented. The effect of CGTase addition to rice flour on dough rheology and bread quality was investigated. In addition, an experimental design was developed to optimize the levels of CGTase, hydroxypropylmethylcellulose (HPMC), and oil. The addition of CGTase produced a reduction in the dough consistency and also in the elastic modulus. With regard to the rice bread quality, better specific volume, shape index, and crumb texture were obtained. The amount of cyclodextrins in the bread crumb was quantified to explain the action of this enzyme. The data indicate that the improving effect of the CGTase results from a combination of its hydrolyzing and cyclizing activities, the latter being responsible for the release of cyclodextrins, which have the ability to form complexes with lipids and proteins.