Thesis (M.S.)--Brigham Young University. Dept. of Plant and Animal Sciences, 2006. / Includes bibliographical references (p. 31-37).

Techn. Universiẗat, Diss., 2000--Berlin.

The overarching goal of this research was to investigate the effect of cultivar and environment on the physicochemical and functional properties of pea protein isolates using a structure-function approach. Six pea cultivars (Agassiz, CDC Golden, CDC Dakota, CDC Striker, CDC Tetris, Cooper) were collected from two years (2011, 2012) over two locations in Saskatchewan (Saskatoon and Rosthern) from two field replicates. Pea protein isolates were prepared from defatted flours by alkaline extraction (pH 9.0) followed by isoelectric precipitation (pH 4.5), and then neutralized to pH 7.0 prior to freeze-drying. Samples were evaluated for composition (amino acid profile, legumin/vicilin ratio), surface characteristics (zeta potential, surface hydrophobicity), and functional properties (nitrogen solubility, oil holding capacity, foaming capacity, foam stability, emulsion stability). In addition, samples were assessed for seed weight and colour, and compared against the functional characteristics of six commercially produced protein isolates (whey, wheat, egg, pea, and two soy ingredients). The extracted pea protein isolates had protein contents of ~91% (d.b.), as well as isolate and protein yields of ~18% and ~72%, respectively. Although cultivars exhibited a range of legumin/vicilin ratios from 0.36 (Agassiz) to 0.79 (CDC Golden), such differences were not reflected in their amino acid profiles. Differences amongst cultivars, as well as significant cultivar × environment interactions, were found for only surface hydrophobicity (195-267 a.u.), solubility (63-75%), and foaming capacity (167-244%). No differences in either cultivar or environment were observed in other surface (zeta potential = ~-24 mV) or functional (oil holding capacity = ~3.2 g/g; foam stability = ~75%; emulsion stability = ~96%) properties. All functional properties were significantly correlated with legumin/vicilin ratio and/or surface hydrophobicity. However, such relationships were weak (r = -0.19 to -0.20, and r = 0.17 to 0.32). The strongest correlation was observed between the legumin/vicilin ratio and surface hydrophobicity at r = 0.63 for the pea protein isolates. Meanwhile, zeta potential did not display a significant correlation to any property tested. In comparison to commercial protein isolates, the pea protein isolates behaved most similarly to soy except for solubility. Whey and egg were superior in solubility and the foaming properties, whereas wheat and the commercial pea protein product underperformed in almost all functionality tests. These findings suggest that while inherent protein material source may be important to functional behaviours, the method of extraction could pose even greater effects. This was observed between the laboratory- and commercially-prepared pea protein isolates, which at minimum differed in processing (defatting) and method of drying (freeze- vs. spray-dried). Coupled with the weak correlations between physicochemical and functional properties, findings overall indicate that method of protein isolate production play a more significant role in protein functional characteristics than cultivar, environment, or composition. Findings also suggest that secondary processors may not need to specify either cultivar or environment of their raw materials, thus creating advantages in their feedstock sourcing.

Quinoa (Chenopodium quinoa) is an Andean crop adapted to harsh environmental conditions and containing a high and well-balanced protein composition. Two seed storage proteins, the 2S albumin and 11S globulin, are the major amino acid reservoirs for the developing seedling. An in-depth study of the genes encoding these proteins is necessary to understand the source of quinoa's protein quality. Our objectives include identification and sequencing of the 11S genomic and cDNA clones, analysis of 11S expression profiles in different quinoa accessions and evaluation of evolutionary relationships between the sequence of the 11S gene in quinoa and homologous genes in other species. Clones containing 11S cDNA and genomic DNA were identified and sequenced. Two copies of the gene were found to be present at two different loci in the quinoa genome. The amino acid composition of the 11S gene was also analyzed. Results show that the 11S gene contains a well-balanced assortment of essential amino acids with relatively high levels of glutamate/glutamine, aspartate/asparagine, arginine, serine, leucine and glycine, typical of other 11S seed storage proteins. Total RNA and globulin was extracted from seed collected at different developmental intervals from nine quinoa accessions. Expression profiles were determined by evaluating 11S transcript levels using relative quantification real time RT-PCR and comparing relative 11S globulin accumulation using sodium SDS-PAGE. The 11S gene was found to be expressed during late-maturation regardless of differences in maturation rate. A portion of the amino acid sequence of the 11S and homologous genes was chosen for phylogenetic analysis. Fifty five such sequences from 50 different plant species were assembled and aligned. Two phylogenetic reconstructions, one using the parsimony method and the other using Bayesian analysis, were generated in order to analyze evolutionary relationships between the 11S gene in quinoa and homologous genes in other species. Relationships shown by both reconstructions for sequences from closely-related species were consistent with taxonomic clustering. Both reconstructions showed less resolution involving relationships between distantly-related angiosperm taxa indicating a wide divergence of sequence at the angiosperm level and a need for additional angiosperm sequence data for finer resolution.

Proteiner spelar en avgörande roll i människokroppen och det är därför viktigt att inta tillräckligt med essentiella aminosyror genom kosten. Tidigare har animaliska källor varit kända för att vara rika på dessa aminosyror, men nu förtiden räcker det inte för att tillfredsställa den globala behov. Dessutom väcker den animaliska proteiner allvarliga frågor om klimatförändringar och etik. Ärtor innehåller en essentiell profil av aminosyror och har många andra fördelar, såsom tillgänglighet, kostnadseffektivitet och förmåga att växa i låga temperaturer. Tidigare studier har visat att regelbunden intag av ärtprotein kan minska risken för hjärt-kärlsjukdomar och diabetes. Studier visade att Naturliga djupa eutektiska lösningsmedel (NADES) kan lösa upp proteiner utan att denaturera de, vilket är ett problem med traditionella lösningsmedel som kan påverka proteinstrukturer. Dessutom är NADES icke-toxiska och biologiskt nedbrytbara lösningar, vilket gör dem mer hållbara och miljövänliga än vanliga vätskor som används vid proteinextraktion. Syftet med studien var att använda NADES för att utveckla en ny metod för att extrahera proteiner från gula ärtor och jämföra denna med etablerade metoder. Dessutom skulle skillnader i proteinutbyte och strukturella förändringar uppskattas genom användning av Size Exclusion Chromatography (SEC) och Sodium Dodecyl Sulfate PolyAcrylamide Gel Elektrofores SDS-PAGE. Tre varianter av NADES framställdes från kolinklorid, citronsyra och olika vattenhalter. NADES 20% användes för extraktion, eftersom det har visat sig vara en lämplig metod för detta ändamål. Resultaten visade att extraktion med NADES är mer komplicerad än referensmetoderna för att proteinerna utfölls vid olika steg under extraktion process. SEC-kromatogram visade proteindenaturering där en tydlig topp erhölls vid senare elueringsvolym. SDS-PAGE analys genomfördes för att identifiera toppar men inge resultat kunde erhålla på grund av låg proteinkoncentration. Från ett optimistiskt perspektiv kan de denaturerade proteinerna fortfarande användas inom livsmedelsindustrin eller NADES kan användas som en pre-extraktionsmetod för att avlägsna föroreningar innan den verkliga extraktionsprocessen påbörjas. Det skulle vara användbart för framtida studier att prova att extrahera med en lägre vattenhalt i NADES eller med en annan typ av NADES. / Protein plays a crucial role in the human body, making it essential to consume sufficient amounts of essential amino acids through diet. Traditionally, animal sources have been known to be rich in these amino acids, but this is not sufficient to meet global demand. Additionally, this raises serious questions about climate change and ethics. Peas have been found to contain an essential profile of amino acids and have many other advantages, such as availability, cost-effectiveness, and the ability to grow in low temperatures. Previous studies have shown that regular consumption of pea protein can reduce the risk of cardiovascular disease and diabetes. Studies have shown that Natural Deep Eutectic Solvents (NADES) can dissolve proteins without denaturing them, which is a problem with traditional solvents that can affect protein structures. In addition, NADES are non-toxic and biodegradable solutions, making them more sustainable and environmentally friendly than common liquids used in protein extraction. The aim of the study was to use NADES to develop a new protein extraction method from yellow peas and compare this with established methods. In addition, differences in protein yield and structural changes were estimated using Size Exclusion Chromatography (SEC) and Sodium Dodecyl Sulfate PolyAcrylamide Gel Elektrofores SDS-PAGE. Three variants of NADES were prepared from choline chloride, citric acid, and different water contents. NADES 20% was used for extraction as it has been found to be a suitable method for this purpose. The results showed that extraction with NADES is more complicated than the reference methods because the proteins precipitated at different stages during the extraction process. SEC chromatogram showed protein denaturation where a clear peak was obtained at later elution volumes. SDS-PAGE analysis was performed to identify peaks, but no results could be obtained due to low protein concentration. From an optimistic perspective, the denatured proteins can still be used in the food industry, or NADES can be used as a pre-extraction method to remove impurities before the actual extraction process begins. It would be useful for future studies to try extracting with a lower water content in NADES or with a different type of NADES.