Comparison of the effectiveness of alkaline and enzymatic extraction and the solubility of proteins extracted from carbohydrate-digested rice

Abstract

Carbohydrate-digested rice (CDR) residue, the production waste of electrolyte drinks, contains high levels of proteins (approximately 50% of dry matter). Methods for effectively extracting protein from CDR were investigated in this study by comparing alkaline and enzymatic extraction. Alkaline extraction was performed using different concentrations of sodium hydroxide (NaOH). Enzymatic extraction was performed with either commercial Alcalase ® or Flavourzyme ®. Protein recovery and solubility, and total soluble protein obtained via each method were compared to determine extraction effectiveness. In addition, extraction factors affecting protein recovery were adjusted to determine the optimal conditions for each method. Alcalase provided the maximum protein recovery (30.04%), while less protein recovery was achieved with 0.1 N NaOH (55 C), 1 N NaOH (55 C), and Flavourzyme. Although the protein recovery achieved by 0.1 N NaOH (27.43%) was close to that of the Alcalase method, protein solubility by extraction with 0.1 N NaOH was much lower (23.46%) than that achieved via the enzymatic method (100%). Hence, the total soluble protein resulting from Alcalase extraction was higher than that obtained using either of the alkaline methods. Consequently, Alcalase extraction was determined to be the most effective method for extracting protein from CDR.

A Narrative Review on Rice Proteins: Current Scenario and Food Industrial Application

“…Prolamin: Prolamins are also called reserve proteins because they are found in the endosperm area of the grain. They are deficient in essential amino acids but have non-essential amino acids [ 31 ]. Rice prolamins soluble in aqueous ethanol (60–70%) are about 4% of the bran, the minor fraction in rice seed constitutes 2.6–3.3%.…”

“…On the other hand, rice bran proteins made up of fractions like albumin, globulin, glutelin, and prolamin, as shown in Figure 3 , come in the range of 10–100 KDa, 10–150 KDa, 33–150 KDa, and 25–100 kDa, respectively. Rice albumin is highly heterogeneous [ 31 ] because it contains protein with MW 10 to 200 kDa. Noticeably the pre-dominant weights are 16 kDa protein and 60 kDa glycoprotein.…”

Monodisperse Plant Protein Nanoparticles Prepared by Cation-Exchange Resins for Stabilization of Pickering Emulsions

“…2 After alkali extraction, the aqueous proteins are recovered by acid-induced precipitation using hydrochloric acid to lower the pH to around the isoelectric point (pI), which is accompanied by the generation of sodium chloride. 3 The aggregation behavior of proteins strongly depends on the concentration of salts, 4 i.e., salting-in and salting-out effects at low and high salt concentrations, respectively, which is associated with electrostatic repulsions at the protein−water interface. 5 For most cereal proteins, e.g., rice proteins (RP) containing over 80% glutelins by weight, a basicity as high as pH 12.0 is generally used for protein extraction, leading to salting-out effects given the considerable amount of salt generated during neutralization.…”

“…However, our understanding of the microstructures of many plant proteins is based on the ancient and conventional methods of alkali extraction and acid precipitation . After alkali extraction, the aqueous proteins are recovered by acid-induced precipitation using hydrochloric acid to lower the pH to around the isoelectric point (pI), which is accompanied by the generation of sodium chloride . The aggregation behavior of proteins strongly depends on the concentration of salts, i.e., salting-in and salting-out effects at low and high salt concentrations, respectively, which is associated with electrostatic repulsions at the protein–water interface .…”

Biological activity of extracts and hydrolysates from early- and adult-stage edible grasshopper Sphenarium purpurascens

“…Despite the great nutritional value of edible insects, the general acceptance of edible insects is low, which has limited their inclusion as part of the daily diet. For this reason, current trends point out the extraction of main nutrients and bioactive molecules to be used as ingredients in food formulations ( 5 ). Antioxidant and anti-inflammatory activities from hydrolysates of edible insects have been reported in crickets ( Gryllodes sigillatus ), mealworm larvae ( Tenebrio molitor ), and desert locusts ( Schistocerca gregaria ) ( 6 ).…”