Physicochemical properties and application in film preparation of prolamin from distiller's grains

Abstract

Prolamin of sorghum-based distiller's grains was extracted and its physicochemical properties were further determined. The prolamin was found to be rich in acidic amino acids, resulting in an isoelectric point of pH 4.0. High content of α-helix structure endowed the protein good thermostability with a denaturation of 123.47 °C. The prolamin was resistant to pepsin but susceptible to trypsin in vitro digestion. The nutritional evaluation score was low and the protein does not belong to a good source of food protein due to the low digestion and lack of essential amino acids. The prolamin exhibited low water-holding capacity, oil-holding capacity, foam properties, and emulsifying properties. Moreover, the protein possessed good film-forming properties, and the characteristics of high temperature resistance, low water-holding capacity and oil-holding capacity of prolamin can endow the protein film with excellent properties of water blocking, oil blocking, and high thermal stability.

Impact of milling on the nutrients and anti‐nutrients in browntop millet (Urochloa ramosa) and its milled fractions: evaluation of their flour functionality

“…These results are consistent with the reported nitrogen solubility of foxtail millet flours 45 . Water‐insoluble protein fractions such as prolamin and glutelin (rich in acidic amino acids) make up the majority of the protein content in millets with an isoelectric point (pI) of pH 4.0 46 . Similarly, flours of browntop millet milled fractions may also have higher prolamin and glutelin content than albumin and globulin resulting in poor solubility profile at their isoelectric pH.…”

“…45 Water-insoluble protein fractions such as prolamin and glutelin (rich in acidic amino acids) make up the majority of the protein content in millets with an isoelectric point (pI) of pH 4.0. 46 Similarly, flours of browntop millet milled fractions may also have higher prolamin and glutelin content than albumin and globulin resulting in poor solubility profile at their isoelectric pH. Maximum protein solubility observed in browntop millet milled fractions at alkaline conditions (pH 8-12) may be due to the large increase in water-protein interactions and electrostatic repulsive forces between molecules above the pI.…”

The Composition, Structure, and Functionalities of Prolamins from Highland Barley

“…Four kinds of proteins have been established in crops, including prolamin, glutelins, albumins, and globulins [ 4 ]. Prolamin is a kind of storage protein in seeds, providing both carbon and nitrogen elements [ 5 ]. Prolamins have high content of hydrophobic amino acids (such as alanine, proline, and leucine), which can be easily dispersed in alcoholic solutions.…”

“…For instance, due to the difference of protein conformation and aggregation, zeins, hordeins, and gliadins exhibit different electrospinnabilities and emulsifying and film-forming properties, etc. [ 5 , 9 , 10 , 11 , 12 , 13 , 14 ]. However, little is known about the structural and physicochemical properties of prolamins from highland barley, limiting its application.…”