C H Vinnett | PubMed Health

PubMed1980

Aspects of parasexual analysis in Aspergillus parasiticus.

A scanning electron microscopic examination of the surface ornamentation of haploid, heterokaryotic, and diploid conidiospores of Aspergillus parasiticus is presented. Previous studies on the parasexual cycle in this aflatoxin-producing species have shown that heterozygous diploids may be isolated with ease. However, rational genetic analysis of diploids has been hampered by the nonrandom recovery of auxotrophic markers from heterozygous diploids. In this study, a double transfer method involving only brief exposure to p-fluorophenylalanine (FPA) allowed increased recovery of auxotrophic markers from heterozygous diploids. Extensive sampling of green-spored types from FPA-treated diploids provided an estimate of auxotrophic segregants not visually identifiable. We examined seven heterozygous diploids involving three spore color markers and eight auxotrophic markers. In addition, two mutants blocked in aflatoxin production which accumulated visually detectable aflatoxin precursors were analyzed. One linkage between an auxotrophic marker and a spore color marker was detected; however, no evidence for linkage was found between the blocked aflatoxin mutants and the other markers studied.

Aflatoxins↗

PubMed1978

Cottonseed protein derivatives as nutritional and functional supplements in food formulations.

Cottonseeds contain protein with desirable food functional and nutritional properties. Storage globulins make up most of the protein stored in cottonseed and can be separated into five fractions by gel filtration chromatography. Each fraction is distinguishable from the other by its amino acid and polyacrylamide gel electrophoretic properties. Proteins of cottonseed contribute greatly to the functional properties of emulsions, co-isolates, and texturized derivatives. For example, increasing the amount of high protein cottonseed flour in wheat suspensions from 2% to 10% improved the capacity (54-97 ml of oil) and viscosity (5,000-100,000+ cps) of emulsions. The 10% suspension formed emulsions with increasing oil capacity (84-100 ml) and viscosity (28,000-100,000+ cps) as the pH was adjusted from 4.5 to 9.5. Consistencies of the products ranged from that of salad dressing (low percent suspensions, or acid pH) to that of mayonnaise (high percent, or basic pH). These data were utilized to derive a multiple regression model to predict optimum use of cottonseed proteins in emulsions of varying consistencies. A coprecipitated isolate containing greater than 94% protein was prepared from a blend of cottonseed and peanut flours. Amino acid content of the co-isolate reflected that of the protein in the two flours of the composite. The co-isolate has lower gossypol level and improved color and functional properties than a cottonseed protein isolate. Storage protein isolate of cottonseed suspended in aqueous solution and heated with constant stirring forms a texturized product; the quality of the product depends on heat, pH, salt, and the quantity of nonstorage proteins. Protein and amino acid content of meat products were improved by the addition of the texturized protein of cottonseed.

Amino Acids↗