Characterization of the proteins and flour of Distichlis palmeri (Vasey) grain and Distichlis spp. fiber.

Abstract

Proteins from a halophyte cereal Distichlis palmeri, whole-grain flour were fractionated on the basis of their solubility. Five fractions were obtained and each analyzed for fifteen amino acids. The amino acid pattern of the whole-grain was similar to that of a cereal. The percent of amino acids for the ethanol extraction ranged from a high of 35% glutamine to a low of 0.18% lysine. The fractions were rich in asparagine and glutamines. The lysine content of this grain is higher than that of wheat and the highest percentage (6.3%) was found in the water soluble fraction. Protein recovery of the different fractions ranged from 78% to 87%. SDS polyacrylamide gel electrophoresis showed that the water soluble fraction had a wide range of molecular weight proteins; the NaCl fraction had circa 10 proteins in high concentrations; the prolamine fraction had a band at about 22,000 daltons with two weak bands at 45,000 and 66,000 daltons; the 2-mercaptoethanol fraction had few weak bands, and the SDS fraction had circa 6 bands present in high concentrations. The foaming capacity and stability of the albumin fraction of Distichlis palmeri was excellent. The whole-grain flour of Distichlis palmeri had a better water and oil holding capacity as g/g protein. The emulsion capacity of the whole-grain flour was also better than in its protein fractions. When evaluated with a Hedonic scale for taste preference there was no significant difference in flavor acceptance between the "exclusive" eaters and "frequent" eaters of whole-wheat products. Overall, the "exclusive" eaters of whole wheat rated Distichlis palmeri muffins significantly higher than either the "occasional" eaters or the "frequent" eaters. The 50/50 mix received the highest rating. The grain of Distichlis palmeri has 5.15% soluble fiber and 12.7% of insoluble fiber. No trypsin inhibitor activity was detected in the flour. The two forages (Distichlis spp.) analyzed had 6.10% and 15.20% of protein respectively. Acid detergent fiber was 33% and 20%. Low lignin was found in both grasses (6.8% and 5.10%). Mineral content for both forages was: Ca (0.3% and 0.5%); Mg (0.09% and 0.2%); P (0.12% and 0.21%); Zn (6.2 ppm and 20 ppm), and Cu (5.5 ppm and 6.7 ppm).