PHYSICO-CHEMICAL, FUNCTIONAL AND THERMAL CHARACTERIZATION OF DIFFERENTLY TREATED BARNYARD (Echinochloa esculenta), FOXTAIL (Setaria italica) AND LITTLE (Panicum sumatrense) MILLET FLOURS
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Date
2022-03-01
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PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY
Abstract
Today's health trends shift from reactive to proactive and from treatment to
prevention. There is a growing awareness of the importance of health and nutrition and a
growing desire to lead an active and healthy lifestyle. This is driving the consumption of
millet with increasing awareness of its health benefits. Epidemiological studies have
shown that regular consumption of millets reduces the risk of heart disease, minimizes
the onset of type II diabetes, improves the digestive system, lowers the risk of cancer,
detoxifies the body, and increases immunity including respiratory health and also
Parkinson’s disease. Several initiatives are also being undertaken toward enhancing
millet cultivation and consumption to reduce health risks. To improve the consumption
of millets to a desirable level, in addition to sufficient production, products of commercial
importance should be made available in the market. Flour is a basic ingredient for many
products across the world. Earlier studies on pretreated flours were not fully investigated.
Thus, the aim of the study was to elucidate the differently treated millet flours in terms
of physical, functional, thermal, pasting, rheological, nutritional and antioxidant
properties.
In the present study, three types of minor millets viz., barnyard (BM), foxtail (FM)
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and little millet (LM) were selected. Both the whole and dehulled grains were subjected
to soaking, germination, fermentation, dry heating, hydrothermal and extrusion
treatments after optimization and converted into flours. The resultant flours were
examined for physical, functional, pasting, nutritional and antioxidant properties. Storage
stability was studied for 90 days. Overall, there was a significant effect of the treatments
in all the grains in the different properties studied. Multivariate analysis revealed that the
effect was due to treatments than the grains.
The mean values of loose bulk density (LBD), tapped bulk density (TBD), color
attributes L*, a*, b*, pH, and sedimentation value (SV) were 0.54 (g/ml), 0.68 (g/ml),
18.37 27.88, 3.20, 6.57 and 1.92ml, respectively. LBD of the whole, whole soaked (WS),
germinated, fermented and whole hydrothermal (WHT) flours were lower than their
respective means. WS, WHT, whole extruded, fermented, and dry heated flours have
lower TBD than their respective means.
Evaluation of functional properties indicated that water holding capacity (WHC),
water absorption capacity (WAC), water solubility index (WSI), swelling power (SP),
and swelling index (SI) were significantly improved by extrusion, hydrothermal
treatment, germination, and dry heating. The mean WHC, WAC, WSI, SP, SI, foaming
capacity (FC) and oil retention capacity (ORC) were 181.44 (%), 6.61%, 3.89, 318.19,
1.41 (g/dl), 13.42 % and 2.14%, respectively. Apart from untreated, whole soaked and
whole dried (WDr) flours exhibited higher foaming capacity (FC%) followed by their
dehulled counterparts. Foaming was not observed in extruded flours. Whole extruded
(WE) and dehulled soaked (DS) flours exhibited highest and lowest ORC, respectively.
Measurements of gelatinization temperature revealed a significant effect of
treatments and grain on the gelatinization temperature of the millet flours. There was no
significant effect of grains on Tc and enthalpy. Hydrothermally treated (HT) followed by,
extruded and soaked exhibited the lowest onset, peak and conclusion temperature, while
the dehulled fermented flours (DFF) were highest. Enthalpy was lowest in germinated
flours (GFFs) and highest in dehulled dry heated flours (DDrF) (P< 0.05).
Extrusion significantly improved the mean pasting viscosity (PV) from 244.80 to
4034.33 cP in whole and 227.87 to 3606.33 cP in dehulled flours followed by germinated
flours (244.80 to 547.53). DSF, DDrF, DHTF, DFF, and dehulled flours exhibited similar
(P<0.05) high peak viscosity (PKV). Extruded followed by germinated flours have very
low PKV. Break down viscosity (BV) was significantly high in DDrF, DFF at par with
dehulled untreated flours. DSF followed by WHTF and DHTF followed by DFF showed
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very high holding viscosity (HV) and Final viscosity (FV) than others, while those of
germinated and extruded flours were lower than others. Setback viscosity (SV) of
extruded flours, DFF, WHTF and DHTF was significantly higher than others, with no
difference among them. Storage and loss modulus were increased in all the treated whole
barnyard flour doughs except extruded dough. Among all the millet flours, extruded
flours exhibited the lowest G′′ and G′.
Significantly higher ash, protein, and crude fibre content was in WEF, DHTF and
DDrF, respectively. No significant effect of treatments on carbohydrate and fat content.
More remarkable improvement was in whole grain treatments than that of dehulled grain.
Zinc (6.93 mg/100 g), iron (4.93 mg/100 g), and calcium (42.88 mg/100 g) contents were
enhanced in DSF, DSF and Germinated flours, respectively (p<0.05), while extrusion
improved potassium levels. Dry heating lowered the protein content. HTF and WFF
increased TFC, while that of TPC and tannins increased in extruded flours, which was
reflected in lower IC50 and increased DPPH % inhibition values. Dehulled treated flours
reduced a higher percentage of oxalates (78.2 to 128.5%) than whole treated (50.6 to
72.2%). Storage of all the flours did not adversely effect the shelf life.
Thus, the study demonstrated that treated flours can be developed with enhanced
nutrition, physical, functional, thermal, and rheological properties. Further studies on the
in vitro digestibility and glycemic index would help promote these flours as functional
ingredient
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D10829