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.

A review of starch, a unique biopolymer - Structure, metabolism and in planta modifications

Starch is a complex carbohydrate polymer produced by plants and especially by crops in huge amounts. It consists of amylose and amylopectin, which have α-1,4- and α-1,6-linked glucose units. Despite this simple chemistry, the entire starch metabolism is complex, containing various (iso)enzymes/proteins. However, whose interplay is still not yet fully understood. Starch is essential for humans and animals as a source of nutrition and energy. Nowadays, starch is also commonly used in non-food industrial sectors for a variety of purposes. However, native starches do not always satisfy the needs of a wide range of (industrial) applications. This review summarizes the structural properties of starch, analytical methods for starch characterization, and in planta starch modifications.

Effects of tempering (annealing), acid hydrolysis, low-citric acid substitution on chemical and physicochemical properties of starches of four yam (Dioscorea spp.) cultivars

The effects of tempering (annealing), acid hydrolysis and low-citric acid substitution on chemical and physicochemical properties of starches of four Nigerian yam cultivars were investigated. Crude fat and protein contents of the native starches decreased significantly after the modifications, while nitrogen-free extract increased significantly with acid hydrolysis and citric acid substitution. Acid hydrolysis and low-citric acid substitution reduced the least concentration for gel formation of the starches from 4 to 2% w/v, but tempering had no effect. Swelling power of the starches reduced significantly, and water solubility increased significantly at 75 and 85 °C, especially with acid hydrolysis and low-citric acid substitution. However, tempering significantly reduced starch solubility in the four cultivars. Paste clarity of starches of white (29.17%), water (18.90%), yellow (30.90%) and bitter (10.57%) yams reduced significantly with tempering to 14.43, 11.83, 16.93 and 7.27%, but increased significantly with acid hydrolysis to 41.40, 35.37, 28.77 and 32.33%, and low-citric acid substitution to 36.60, 44.17, 50.67 and 14.33%, respectively. Pasting properties such as peak, trough, breakdown, final, and setback viscosities and peak time of native starches reduced significantly with acid hydrolysis and low-citric acid substitution, however, tempering significantly increased their pasting temperature, peak time, setback and final viscosities.