Structural, functional, textural characterization and in vitro digestibility of underutilized Kutki millet (Panicum sumatrense) starch

Thermodynamic and network characteristics of optimized lysine-modified kutki (Panicum sumatrense) millet starch hydrogels

Three-dimensional polymeric network of hydrogels avoids its dissolution into the aqueous region. Hydrogels must have strong structural integrity to be used for drug/nutraceutical delivery. A three factor-three-level Box-Behnken design was used to understand the effects of starch concentration, NaCl, and pH on the textural and structural integrity of Lysine modified kutki millet starch hydrogels. Various kinetic models were fitted to the time-course measurement of shrinkage behavior of both conventionally (CDHG) and freeze-dried (FDHG) hydrogel. Increasing the swelling temperature (5-50 °C) showed values of higher molecular weight of polymer chains between neighboring crosslinks ( M c ) ¯ (g/mol) for FDHG (9539.59-56,769.72) than CDHG (1096.28-11,420.48). Similarly, mesh size (ξ) was more for FDHG (38.63-109.53 Ȧ) than CDHG (10.97-42.74 Ȧ). However, other network parameters such as polymer volume fraction ( ∅ p ) was lower for FDHG (0.229-0.146) than CDHG (0.3882-0.222). These values suggest low swelling power of CDHG compared to FDHG. Thermodynamically, FDHG took less energy to swell than CDHG. The study showed that FDHG has better properties than CDHG and could be employed in nutraceutical delivery.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-05953-x.

Investigating the effect of natural fermentation in modifying the physico-functional, structural and thermal characteristics of pearl and finger millet starch

BACKGROUND

In recent years, millets are often considered an emerging crop for sustainable agriculture. Therefore, millets can be exploited as an alternative source of starch which has many applications ranging from food, packaging, bioplastics, and others. However, starch is seldom used in its native form and is more often modified to enhance its functional properties. In literature, many traditional millet-based food recipes often incorporate a fermentation step before cooking. Therefore, using this traditional knowledge fermentation has been explored as a potential method for modifying millet starch.

RESULTS

Pearl millet (PM) and finger millet (FM) flour were allowed to naturally ferment for 24 h followed by starch extraction. Compared to native (N) starch, water/oil holding capacity and least gelation concentration of fermented (F) starch decreased with no significant change in swelling power. The solubility, paste clarity and in vitro digestibility of starch were significantly affected by fermentation. X-ray diffraction (XRD) data indicates that after fermentation, crystallinity increased while the A-type crystalline structure remained intact. Fourier-transform infrared (FTIR) spectra showed no deletion or addition of any new functional groups. Thermal characterization by differential scanning calorimetry (DSC) showed that the enthalpy of gelatinization of PM starch decreased while that of FM starch increased after fermentation.

CONCLUSION

The results indicate that 24 h natural fermentation had a significant impact on functional properties of starch without altering the structural architecture of starch granules. Therefore, fermentation can be further explored as a low-cost alternative for starch modification. © 2023 Society of Chemical Industry.

Application and functional properties of millet starch: Wet milling extraction process and different modification approaches

In the past decade, the demand and interest of consumers have expanded for using plant-based novel starch sources in different food and non-food processing. Therefore, millet-based value-added functional foods are acquired spare attention due to their excellent nutritional, medicinal, and therapeutic properties. Millet is mainly composed of starch (amylose and amylopectin), which is primary component of the millet grain and defines the quality of millet-based food products. Millet contains approximately 70 % starch of the total grain, which can be used as a, ingredient, thickening agent, binding agent, and stabilizer commercially due to its functional attributes. The physical, chemical, and enzymatic methods are used to extract starch from millet and other cereals. Numerous ways, such as non-thermal physical processes, including ultrasonication, HPP (High pressure processing) high-pressure, PEF (Pulsed electric field), and irradiation are used for modification of millet starch and improve functional properties compared to native starch. In the present review, different databases such as Scopus, Google Scholar, Research Gate, Science Direct, Web of Science, and PubMed were used to collect research articles, review articles, book chapters, reports, etc., for detailed study about millet starch, their extraction (wet milling process) and modification methods such as physical, chemical, biological. The impact of different modification approaches on the techno-functional properties of millet starch and their applications in different sectors have also been reviewed. The data and information created and aggregated in this study will give users the necessary knowledge to further utilize millet starch for value addition and new product development.

In vitro gastrointestinal digestion methods of carbohydrate-rich foods

The trend toward healthier food products has led to an increase in the research of in vitro gastrointestinal digestion methods. Among the most used models, static models are the simplest. Most static models have three stages: oral, gastric, and intestinal, simulating the enzymatic, electrolyte, pH, temperature, and bile salt conditions. The studies that have taken the most notice are those related to antioxidant activity, followed by those dealing with proteins and carbohydrates using most of them static in vitro digestion models. The number of these studies has increased over the years, passing from 45 to 415 in a 10-year period (2012-2023) and showing an interest in knowing the impact of food on human health. Nevertheless, published papers report different methodologies and analytical approaches. This review discusses the similarities and differences between the published static in vitro gastrointestinal digestion methods, with a focus on carbohydrates, finding that the most used protocol is Infogest, but with differences, mainly in the type of enzymes and their activity. Regarding in vitro gastrointestinal digestion of carbohydrates, many of the published studies are related to food and biomacromolecules, being the oral phase the most omitted, while the intestinal phase in the most diverse. Other methodologies to study the intestinal phase have been recommended, but the number of in vitro digestion studies using these methodologies (RSIE and BBMV) is still scarce but could represent a good alternative to analyze carbohydrates foods when combining with Infogest. More studies are required in this area.

Effect of microwave followed by cooling on structural and digestive properties of pinhão starch

To increase its resistant content, native pinhão starch was modified using a microwave (300 W, 90 s) and subsequently cooled at 4 °C for 4, 8, 16, 24, and 72 h. The results demonstrated that all starches exhibited a crystalline structure of type C, with decreased crystallinity after modification. In the modified samples, the ratio of peaks 1047/1022 cm-1 and 995/1022 cm-1, as identified by FTIR, indicated a reduction in the crystalline region and damage to the double helix structure of starch granules. DSC analysis revealed that modified starches had lower gelatinization temperature range values due to the presence of more homogeneous crystals. Rheological analyses showed that starch suspensions obtained exhibited pseudoplastic fluid behavior and gel-like viscoelastic structure formation, with higher storage moduli in samples with longer cooling times. The microwave-modified starch, cooled for 72 h, exhibited higher digestion resistance, resulting in a 43.6 % increase in resistant starch content and a 26.1 % decrease in rapidly digestible starch compared to native starch. The results highlight that the modification of native pinhão starch using a microwave, followed by cooling at 4 °C for 72 h, presents a promising method for increasing the resistant starch content.

Characteristics of physicochemical properties, structure and in vitro digestibility of seed starches from five loquat cultivars

Starch plays a pivotal role in food and other industries, necessitating the exploration of new starch sources to cater the substantial requirement. This study delved into the variations in the physicochemical properties, structure attributes and in vitro digestibility of seed starches extracted from five distinct loquat cultivars (Eriobotrya japonica L.). The starch extraction yield of loquat seeds was found to be 45.2 % as an average. Loquat seed starches were designated as having high-amylose starch (>50 %). The starch granules exhibited similar shapes, but granular size significantly varied across the cultivars. Loquat starches presented a C-type crystalline pattern with relative crystallinity from 17.14 % to 21.06 %. The short-range ordered structure of the starches differed with loquat cultivars. The swelling power, solubility and amylose leaching of loquat starches increased with increasing temperature, significantly varying among different cultivars. Gelatinization parameters exhibited significant variations among the loquat starches. Different loquat starches exhibited pronounced variations in paste clarity, water and oil absorption capacity. Marked differences were detected in proportions of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) across the five cultivars, with RS being particularly prominent fraction with an average of 84.30 %. These compressive findings offer valuable insights into the potential application of loquat seed starches in the formulation of foods and various industrial products.

Characterization and Evaluation of Heat-Moisture-Modified Black and Red Rice Starch: Physicochemical, Microstructural, and Functional Properties

This study sought to evaluate starch from black and red rice modified by heat-moisture, investigating the extraction yield, starch and amylose content, color, and phenolic compounds. The water and oil absorption capacity, whole milk and zero lactose absorption index, syneresis index, and texture were also analyzed. Microstructural analysis included Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The heat-moisture treatment (HMT) reduced the extraction yield and the starch and amylose content, with native black rice starch having the highest values for these parameters. The modification also affected the color and phenolic compounds of the starch, making it darker and changing its appearance. The modification improved the absorption of water, oil, and milk, reducing syneresis and increasing stability during storage. The starch surface was altered, especially for modified black rice starch, with larger agglomerates. The type of starch also changed from A to Vh, with lower relative crystallinity. The textural properties of modified red rice starch were also significantly altered. The HMT proved to be a viable and economical option to modify the analyzed parameters, influencing the texture and physicochemical properties of pigmented rice starch, expanding its applications, and improving its stability during storage at temperatures above 100 °C.

Non-Traditional Starches, Their Properties, and Applications

This review paper focuses on the recent advancements in the large-scale and laboratory-scale isolation, modification, and characterization of novel starches from accessible botanical sources and food wastes. When creating a new starch product, one should consider the different physicochemical changes that may occur. These changes include the course of gelatinization, the formation of starch-lipids and starch-protein complexes, and the origin of resistant starch (RS). This paper informs about the properties of individual starches, including their chemical structure, the size and crystallinity of starch granules, their thermal and pasting properties, their swelling power, and their digestibility; in particular, small starch granules showed unique properties. They can be utilized as fat substitutes in frozen desserts or mayonnaises, in custard due to their smooth texture, in non-food applications in biodegradable plastics, or as adsorbents. The low onset temperature of gelatinization (detected by DSC in acorn starch) is associated with the costs of the industrial processes in terms of energy and time. Starch plays a crucial role in the food industry as a thickening agent. Starches obtained from ulluco, winter squash, bean, pumpkin, quinoa, and sweet potato demonstrate a high peak viscosity (PV), while waxy rice and ginger starches have a low PV. The other analytical methods in the paper include laser diffraction, X-ray diffraction, FTIR, Raman, and NMR spectroscopies. Native, "clean-label" starches from new sources could replace chemically modified starches due to their properties being similar to common commercially modified ones. Human populations, especially in developed countries, suffer from obesity and civilization diseases, a reduction in which would be possible with the help of low-digestible starches. Starch with a high RS content was discovered in gelatinized lily (>50%) and unripe plantains (>25%), while cooked lily starch retained low levels of rapidly digestible starch (20%). Starch from gorgon nut processed at high temperatures has a high proportion of slowly digestible starch. Therefore, one can include these types of starches in a nutritious diet. Interesting industrial materials based on non-traditional starches include biodegradable composites, edible films, and nanomaterials.

Effects of pin-to-plate atmospheric cold plasma for modification of pearl millet (Pennisetum glaucum) starch

The present study was done to analyze the effect of atmospheric pressure non-thermal pin-to-plate plasma at a range of different voltages (170, 200, and 230V) at different time intervals (10, 20, and 30 mins) on under-utilized pearl millet starch. The untreated and treated starches were analyzed for amylose content, pH, carbonyl, and carboxyl group, reducing sugar, turbidity, water, and oil binding property, pasting property, DSC, FTIR, XRD, and molecular weight. As cold plasma contains highly reactive species and free radicals, it is expected to cause noticeable modifications in the attributes of treated starch. There has been a significant reduction (p < 0.05) in turbidity value by 38.97% and pH value of starch from 6.49 to 4.05. Plasma-treated samples produced clearer pastes with higher stability over storage time. Cold plasma treatment also led to an increase in the ζ potential. However, there has been no significant change in the water activity and oil-binding capacity of the starch. Reducing sugar content, average molecular weight, degree of polymerization, pasting property, XRD, and FTIR data confirmed that cross-linking takes place in samples treated at lower voltages and lesser time followed by depolymerization occurring in harshly treated plasma samples. The study thus points out the possible use of cold plasma for starch modification to produce starches with altered properties.