Underutilized finger millet crop for starch extraction, characterization, and utilization in the development of flexible thin film.

Three different varieties of finger millets (VL-315, VL-324, and VL-347) cultivated in Uttrakhand, India, were used to extract high purity starch using the alkali soaking approach and investigated physicochemical and structural properties. VL-315, VL-324, and VL-347, contain 78 ± 0.35%, 79 ± 0.35%, and 87 ± 0.35% starch, respectively, of which 39.03 ± 0.35%, 37.2 ± 0.35%, and 33.5 ± 0.35% are the amylose contents, respectively. Chemical composition analysis exhibited the level of ash and moisture content in the dry basis of 0.0031 ± 0.01% to 0.035 ± 0.05%, and 12.52 ± 0.8% to 12.92 ± 0.2%, respectively. The solubility and swelling range of VL-315 is 1.3-4.3% and 16.54-10.3 (g/g), respectively, which significantly differ from VL-324 and VL-347. XRD analysis revealed that extracted starch showed a typical A-type crystalline network with a crystallinity range of 17.7-19.3%, which remarkably influenced retro gradation tendencies of starch. SEM demonstrated that extracted starch granules are polyhedral shape with a smooth surface. Finger millet starch has enormous potential in the development of starch-based edible film and coating on food items. In the present work, extracted finger millet starch was studied with the aim of developing a thin and flexible food packaging film. From the results, it was observed that the fabricated films had excellent functional properties, including solubility, swelling index, and water vapor permeability, which could eliminate petroleum-based packaging materials, and gives food materials an extra shelf life, and improve overall food quality.

Rheological and functional properties of heat moisture treated pearl millet starch.

Pearl millet (Pennisetum typhoides) starch was subjected to heat moisture treatment (HMT) at different moisture levels i.e., 20 % (HMT-20), 25 % (HMT-25) & 30 % (HMT-30) for 8 h at 110 °C and evaluated for changes in rheological, thermal, functional and morphological properties. Peak, breakdown, cool paste and setback viscosity decreased, while pasting temperature increased after HMT. Shear stability of HMT-30 sample was maximum (stability ratio 0.54). Highest (33.5 Pa) G' value was observed for native and lowest (14.8 Pa) for HMT-25 sample. Yield and flow point of starch gels also decreased after HMT, indicating softer gels and higher spreadability. HMT increased gelatinization temperature from 62.59 °C for native to 84.05 °C for HMT-30. Resistant starch content increased about three times in HMT-30 sample (7.07 %) as compared to native. Swelling power and solubility decreased after HMT. HMT also induced cavity and some dents on starch granules surface.

Effects of benzalkonium chloride as a cationic surfactant on the physicochemical properties of adlay millet starch films.

The effects of benzalkonium chloride (BC) as a cationic surfactant on the mechanical, water barrier, microstructural, and thermal properties of adlay millet starch (AS) films were investigated in this study. With increasing BC concentration, tensile strength (from 5.93 to 6.15 MPa) and elongation at break (from 41.39 to 45.48%) of AS-BC films significantly increased, whereas their moisture content, water solubility, and water vapor permeability were reduced, indicating water resistance improvement. Fourier transform infrared spectroscopy and scanning electron microscopy analysis showed that BC at concentrations below 1% did not cause noticeable changes in the microstructure of AS-BC films. In addition, the thermal stability of AS-BC films was not affected by BC, indicating good miscibility between AS and BC. Therefore, BC could improve the physicochemical properties of starch films, and AS-BC films developed in this study can be applied as novel biodegradable packaging materials in the food packaging industry. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01383-1.

Amylopectin chain length distributions and amylose content are determinants of viscoelasticity and digestibility differences in mung bean starch and proso millet starch.

This study aimed to reveal the underlying mechanisms of the differences in viscoelasticity and digestibility between mung bean starch (MBS) and proso millet starch (PMS) from the viewpoint of starch fine molecular structure. The contents of amylopectin B2 chains (14.94-15.09 %), amylopectin B3 chains (14.48-15.07 %) and amylose long chains (183.55-198.84) in MBS were significantly higher than PMS (10.45-10.76 %, 12.48-14.07 % and 70.59-88.03, respectively). MBS with higher amylose content (AC, 28.45-31.80 %) not only exhibited a lower weight-average molar mass (91,750.65-128,120.44 kDa) and R1047/1022 (1.1520-1.1904), but also was significantly lower than PMS in relative crystallinity (15.22-23.18 %, p < 0.05). MBS displayed a higher storage modulus (G') and loss modulus (G'') than PMS. Although only MBS-1 showed two distinct and discontinuous phases, MBS exhibited a higher resistant starch (RS) content than PMS (31.63-39.23 %), with MBS-3 having the highest RS content (56.15 %). Correlation analysis suggested that the amylopectin chain length distributions and AC played an important role in affecting the crystal structure, viscoelastic properties and in vitro starch digestibility of MBS and PMS. These results will provide a theoretical and scientific basis for the development of starch science and industrial production of low glycemic index starchy food.

Effects of Lactobacillus plantarum fermentation on the structure, physicochemical properties, and digestibility of foxtail millet starches.

This study investigated the effects of Lactobacillus plantarum fermentation on the structural, physicochemical, and digestive properties of foxtail millet starches. The fermented starch granules formed a structure with honeycomb-like dents, uneven pores, and reduced particle size. As the fermentation time extended, the amylose content of waxy (0.88 %) and non-waxy (33.71 %) foxtail millet starches decreased to the minimum value at 24 h (0.59 % and 29.19 %, respectively), and then increased to 0.85 % and 31.87 % at 72 h, respectively. Both native and fermented foxtail millet starches exhibited an A-type crystal structure. Compared with native samples, the fermented samples performed enhanced proportion of short-branched chain, crystallinity, and short-range ordered degree. After fermentation for 24 h, the solubility, adsorption capacity, and pasting viscosity of foxtail millet starches improved, whereas the swelling power, pasting temperature, breakdown, setback, and degree of retrogradation reduced. Additionally, fermentation increased the transition temperatures, enthalpy, and digestibility. Overall, Lactobacillus plantarum fermentation is considered a competent choice to regulate the characteristics of foxtail millet starch.

Rheological and gelling properties of atmospheric pressure cold plasma treated finger millet (Eleusine coracana) starch.

Interest in exploring alternative starch sources like finger millet is rising due to wide starch applications. However, native starch often lacks desired qualities, including rheological properties. Modification is thus necessary for specific end uses. Plasma treatment as a greener and sustainable method for starch modification was therefore, studied for its ability to impact rheological properties of finger millet starch (FMS). Considerable changes in the rheological properties on FMS was noted, a significant decrease and increase (p < 0.05) in the peak viscosity (from 3.35 to 0.553 Pa.s) and paste clarity respectively was observed, indicating occurrence of depolymerization. However, intermediate plasma-treated samples (200 V) observed a decrease in paste clarity attributed to aggregate formation and cross-linking. Cross-linking was also confirmed by findings of frequency sweep where a continuous decrease in G' values of plasma treated FMS gel was interrupted by sudden increase. Despite depolymerization causing alteration of rheological behaviour such as decrease in shear thinning properties, gel strength observed a contradictory increase. This was attributed to incorporation of functional group and absence of shear responsible for network formation giving higher gel strength to FMS gels. This is elaborated in detail in the study. The study thus concluded that cold plasma significantly impacted all the rheological properties of the FMS and hence can prove to be beneficial for modification of starch rheological parameters.

Exploring the potential of browntop millet (Urochloa ramosa) starch: Physicochemical, morphological, thermal and rheological properties across four cultivars.

This comprehensive research explores the starch isolated from four browntop millet cultivars to determine physicochemical, thermal, morphological, powder flow, pasting, and rheological properties. Significant variations (p ≤ 0.05) were observed among the cultivars. Aerated bulk density (ABD) and Tapped bulk density (TBD) values ranged from 0.476 g/mL (BTM4) to 0.591 g/mL (BTM1), and 0.591 g/mL (BTM1) to 0.476 g/mL (BTM4). Amylose content varied from 22.55% (BTM4) to 25.86% (BTM3), influencing gelling strength and film-forming properties. Water absorption capacity ranged from 1.78 g/g to 1.92 g/g, while oil absorption capacity varied from 2.20 g/g to 2.47 g/g. DSC analysis showed gelatinization temperatures (Tp, and Tc) ranging from 85.44-91.61 °C, and 147.08-154.21 °C, respectively. X-ray diffraction (XRD) patterns revealed A-type crystalline patterns, with relative crystallinity ranging from 22.66% (BTM3) to 27.81% (BTM2). Pasting properties exhibited variations among cultivars, with peak viscosity ranging from 2480 c P to 3119 cP, and pasting temperature from 77.50 °C to 82.35 °C. Rheological analysis indicated shear-thinning behavior. The findings offer insights into the diverse properties of browntop millet starch, contributing to its potential applications in various industries and potentially guiding future studies on browntop millet starch modifications and novel utilization.

Starch chain-length distributions affect the processing and digestion characteristics of proso millet starch.

Starch chain-length distributions play a key role in regulating the processing and digestion characteristics of proso millet starch. Waxy proso millet starch has higher endothermic enthalpy (13.06-16.73 J/g) owing to its higher relative crystallinity (27.83%-32.04%), while nonwaxy proso millet starch has lower peak viscosity (1.0630-1.1930 Pa∙s) and stronger viscoelasticity owing to its higher amylose content (21.72%-24.34%). Non-waxy proso millet starch exhibited two different digestion phases and its resistant starch content (18.37%-20.80%) was higher than waxy proso millet starch. Correlation analysis showed proso millet starch with longer amylopectin B1 chains and more amylopectin B2 chains exhibited excellent thermal ability and retrograde resistance, whereas proso millet starch with shorter and more amylose medium/long-chains not only reduced the digestion rate and increased the resistant starch content but also exhibited stronger viscoelasticity and excellent retrogradation properties. These results could provide more insights into efficient utilization of proso millet starch.

Structure, physicochemical, functional and in vitro digestibility properties of non-waxy and waxy proso millet starches.

The structural, physicochemical, gel textural, rheological, and in vitro digestibility properties as well as their relationships of non-waxy proso millet starch (NPMS) and waxy proso millet starch (WPMS) were evaluated by taking normal corn starch (CS) and potato starch (PS) as controls. Proso millet starch was mostly polygonal or spherical, with an A-type crystalline structure. Proso millet starch contained more short-branched chains (DP 6-24) compared with CS and PS. WPMS possessed higher crystallinity and more short-range ordered structures than NPMS. NPMS displayed higher pasting temperature, retrogradation rate and shear thinning degree, and lower gelatinization temperature and enthalpy than WPMS. The hardness and chewiness of starch gel formed by NPMS were higher than those of WPMS. All starch samples exhibited shear thinning behavior in the steady-flow test and typical elastic solid behavior in the dynamic rheological test. Moreover, NPMS was considered a potential formula for functional foods, with its lower rapidly digestible starch (RDS) and higher resistant starch (RS) contents than WPMS, CS, and PS. This paper revealed the influence of amylose content and structure on the physicochemical properties of different proso millet starch.

Physicochemical properties and in vitro digestibility of proso millet starch modified by heat-moisture treatment and annealing processing.

Heat-moisture treatment (HMT) and annealing (ANN) were applied to modify the proso millet starch, and then the physicochemical properties as well as the in vitro digestion of the modified starch were investigated systematically. Results indicated that HMT and ANN did not change the typical A-type crystallinity. However, both processes cause cracks and dents on the surface of the granule. The gelatinization temperature increased while peak viscosity value, relative crystallinity and gelatinization enthalpy of proso millet starch decreased significantly after HTM and ANN. Meanwhile, a remarkable increase of the slowly digestible starch(SDS) and resistant starch(RS) content was noticed after HTM and ANN modification (the highest content of SDS and RS after HTM and ANN were 9.52 ± 0.82 %, 12.03 ± 1.36 % and 12.15 ± 0.89 %, 8.75 ± 1.63 %, respectively). Those results indicated that the ANN and HMT processes could modify the physicochemical properties and in vitro digestion of proso millet starch efficiently and showed potential application to produce healthy starch food with lower digestion.