Browsing by Author "Guo Q"

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    Modifying quinoa protein for enhanced functional properties and digestibility: A review
    (Elsevier B V, 2023-10-05) Cui H; Li S; Roy D; Guo Q; Ye A
    Quinoa (Chenopodium quinoa Willd.) is a pseudocereal plant that originally came from South America. The trend of consuming quinoa is propelled by its well‒balanced amino acid profile compared to that of other plants. In addition, its gluten‒free nature makes quinoa a promising diet option for celiac disease patients. Protein accounts for approximately 17% of the quinoa seed composition and quinoa protein possesses excellent quality. Quinoa protein is mainly composed of 11S globulins (37%) and 2S albumins (35%), both of which are stabilized by disulfide bonds. To date, the alkaline extraction method is the most commonly used method to extract quinoa protein. The functional properties and digestibility of quinoa protein can be improved with the help of various modification methods, and as a result, the application of quinoa protein will be extended. In this review, the extraction method, modification of functional properties and digestibility of quinoa protein are thoroughly discussed, providing insights into the application of quinoa protein in plant‒based foods.
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    Prevalence and genetic diversity of Theileria equi from horses in Xinjiang Uygur Autonomous region, China.
    (Elsevier B.V., 2023-07-01) Zhang Y; Shi Q; Laven R; Li C; He W; Zheng H; Liu S; Lu M; Yang DA; Guo Q; Chahan B
    Theileria equi is a tick-borne intracellular apicomplexan protozoan parasite that causes equine theileriosis (ET). ET is an economically important disease with a worldwide distribution that significantly impacts international horse movement. Horses are an essential part of the economy in Xinjiang which is home to ∼10% of all the horses in China. However, there is very limited information on the prevalence and genetic complexity of T. equi in this region. Blood samples from 302 horses were collected from May to September 2021 in Ili, Xinjiang, and subjected to PCR examination for the presence of T. equi. In addition, a Bayesian latent class model was employed to estimate the true prevalence of T. equi, and a phylogenetic analysis was carried out based on the 18S rRNA gene of T. equi isolates. Seventy-two horses (23.8%) were PCR positive. After accounting for the imperfect PCR test using a Bayesian latent class model, the estimated true prevalence differed considerably between age groups, being 10.8% (95%CrI: 5.8% - 17.9%) in ≤ 3-year-old horses and 35.7% (95%CrI: 28.1% - 44.5%) in horses that were > 3 year-old. All T. equi isolates had their 18S rRNA gene (430bp) sequenced and analyzed in order to identify whether there were multiple genotypes of T. equi in the Xinjiang horse population. All of the 18S rRNA genes clustered into one phylogenetic group, clade E, which is thus probably the dominant genotype of T. equi in Xinjiang, China. To summarize, we monitored the prevalence of T. equi in horses of Xinjiang, China, with a focus on the association between age and the occurrence of T. equi by Bayesian modelling, accompanied by the genotyping of T. equi isolates. Obtaining the information on genotypes and age structure is significant in monitoring the spread of T. equi and studying the factors responsible for the distribution.
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    Structural Properties of Quinoa Protein Isolate: Impact of Neutral to High Alkaline Extraction pH
    (MDPI (Basel, Switzerland), 2023-07-03) Liu S; Xie Y; Li B; Li S; Yu W; Ye A; Guo Q; Tilley M
    In this work, we extracted proteins from white quinoa cultivated in the northeast of Qinghai-Tibet plateau using the method of alkaline solubilization and acid precipitation, aiming to decipher how extraction pH (7-11) influenced extractability, purity and recovery rate, composition, multi-length scale structure, and gelling properties of quinoa protein isolate (QPI). The results showed that protein extractability increased from 39 to 58% with the increment of pH from 7 to 11 whereas protein purity decreased from 89 to 82%. At pH 7-11, extraction suspensions and QPI showed the similar major bands in SDS-PAGE with more minor ones (e.g., protein fractions at > 55 or 25-37 kDa) in suspensions. Extraction pH had limited effect on the secondary structure of QPI. In contrast, the higher-order structures of QPI were significantly affected, e.g., (1) emission maximum wavelength of intrinsic fluorescence increased with extraction pH; (2) surface hydrophobicity and the absolute value of zeta-potential increased with increasing extraction pH from 7 to 9, and then markedly decreased; (3) the particle size decreased to the lowest value at pH 9 and then increased to the highest value at pH 11; and (4) denaturation temperature of QPI had a large decrease with increasing extraction pH from 7/8 to 9/10. Besides, heat-set QPI gels were formed by loosely-connected protein aggregates, which were strengthened with increasing extraction pH. This study would provide fundamental data for industrial production of quinoa protein with desired quality.