Browsing by Subject "toiminnalliset ominaisuudet"

Sort by: Order: Results:

Now showing items 1-3 of 3
  • Ketola, Maija (Helsingin yliopisto, 2020)
    Quinoa has adapted to living under very varied conditions, and within the species, genetic variation is wide. Therefore, there may be differences in the functional properties of quinoa starches between these different varieties and populations. Furthermore, quinoa starch also differs from conventional cereal starches. Thus, knowing these differences is essential in order to find more suitable applications for quinoa in food product development. Increasing the use of quinoa is supported at least by its adaptation to varying growth conditions and nutritional quality. The aim of this master's thesis was to isolate starch from different quinoa varieties and to study the functional properties of starch and to determine the amylose content with the intention to find out whether there are differences in the properties of starches in quinoa varieties. Five different quinoa varieties had been received for this study: Rosada de Taraca, Real quinoa, Titicaca, Pasankalla and Minttumatilda. A separation process was planned for the starch based on previous studies and the separation process was carried out on a laboratory scale. Starch gelatinization properties were measured by RVA (rapid visco analyzer) and by DSC (differential scanning calorimetry) and retrogradation properties by DSC. Amylose content was determined by Megazyme Amylose/Amylopectin Assay Kit. The yield of the separation process remained low. This may have been influenced by the small size of the quinoa starch granules. Differences in gelatinization properties were observed between quinoa varieties. There were more differences at 50% than at 10% starch contents, which could be influenced by different methods. There were also differences in the thermal properties characterizing the retrogradation between the starches at a concentration of 50%. The amylose contents of quinoa starches were low. This may explain why no retrogradation was observed in starch gels containing 10% starch. The starch of the population cultivated in Finland differed from other quinoa starches both in its gelatinization properties and in the thermal properties describing retrogradation. In conclusion, there were differences in the functional properties between the varieties and the choice of quinoa variety is important for the use of quinoa. Quinoa starch differs in characteristics from conventional cereal starches and has its own uses. Thus, increasing the use of quinoa is also supported by the unique properties of quinoa starch.
  • Lukkari, Terhi (Helsingin yliopisto, 2018)
    Kirjallisuuskatsauksessa käsiteltiin yleisellä tasolla hyönteisten turvallisuutta elintarvikkeena, kotisirkan ja jauhomadon koostumusta sekä niiden proteiineja ja proteiinien toiminnallisia ominaisuuksia. Lisäksi kirjallisuusosassa käsiteltiin lyhyesti proteiinien ja rasvojen hapettumista tämän tutkimuksen näkökulmasta. Tutkimuksen tavoitteena oli tutkia prosessoinnin vaikutusta jauhomadon ja kotisirkan proteiinien hapettumiskäyttäytymiseen emulsiossa sekä vaikutusta lipidien hapettumiseen. Lisäksi tavoitteena oli optimoida kotisirkan ja jauhomadon proteiinien uuttomenetelmä. Proteiinien uuttoa optimoitiin eri menetelmillä ja parhaaksi uuttomenetelmäksi osoittautui molemmille hyönteisille uutto-olosuhteet, jossa uuttoliuoksen pH oli 10 ja NaCl -pitoisuus 0,1 M. Jauhomadon proteiinien uuttoon tarvittiin lisäksi rasvanpoisto ennen proteiinien uuttoa. Molempien hyönteisten proteiineja käsiteltiin lämmöllä (+60 °C) ja entsyymillä (transglutaminaasi). Lisäksi jauhomadon proteiinit käsiteltiin uuton yhteydessä sulfiitilla (Na2S2O5) ruskistumisen estämiseksi. Näistä kaikista käsitellyistä proteiineista sekä molempien hyönteisten käsittelemättömistä liukoisista proteiineista valmistettiin emulsiot, joiden hapettumista seurattiin mittausajankohtina 0, 1, 3 ja 7. Proteiinien hapettumista tutkittiin seuraamalla tryptofaanin hajoamista sekä karbonyylien ja dityrosiinin muodostumista fluoresenssispektroskopisella menetelmällä. Lipidien hapettumista tutkittiin seuraamalla konjugoitujen dieenien muodostumista spektrofotometrisesti. Emulsioiden ulkonäköä seurattiin hapettumiskokeen aikana ja emulsioiden partikkelikoko tutkittiin mittausajankohtana 0. Kotisirkan entsyymikäsitellyistä proteiineista valmistetussa emulsiossa proteiinien hapettumista oli havaittavissa, mutta lipidien hapettuminen oli vähäistä. Jauhomadon entsyymikäsitellyistä proteiineista ja kotisirkan lämpökäsitellyistä proteiineista valmistetuissa emulsiossa proteiinien ja lipidien hapettuminen oli vähäistä. Jauhomadon lämpökäsitellyistä proteiinista valmistetussa emulsiossa konjugoituja dieenejä muodostui enemmän kuin muihin näytteisiin. Tässä emulsiossa muodostui karbonyylejä, mutta tryptofaanin hajoamista ei ollut havaittavissa. Sulfiittikäsittely vaikutti altistavan jauhomadon proteiinit hapettumiselle emulsiossa.
  • Nurmi, Emilia (Helsingin yliopisto, 2018)
    The literature review examined structures and functionalities of two major canola proteins, cruciferin and napin. In addition, fundamental functional properties of proteins and the impact of high intensity ultrasound on functionality of other proteins were reviewed. Ultrasound treatment has been successfully used to improve several functional properties of other proteins such as soy, pea and egg white proteins. However, research on high intensity ultrasound treatment for improving canola protein functionality is limited. The aim of the experimental part was to improve solubility, rheological and emulsification properties of canola proteins using high intensity (20 kHz) ultrasound. The effects of ultrasound treatment on protein structures were also examined. Canola samples were first preheated (95 °C, 5 min) and then treated with ultrasound at different power intensity levels (200 and 400 W) and durations (10 and 30 min). Albumin fractions were obtained by water extraction (pH 7.3) and NaCl extraction (1 M, pH 6.3) was used to obtain globulin fractions. The soluble protein concentration was determined using DC Protein Assay (Bio-Rad, USA), free sulfhydryl content was measured according to Ellman’s procedure and electrophoresis (SDS-PAGE) was performed for the determination of protein composition. Emulsifying ability, creaming index, average particle size, viscosity, storage modulus (G’) and loss modulus (G’’) were determined from the heat-induced emulsion gels. Solubility and emulsion stability of ultrasound treated canola samples were improved compared to control samples. In addition, ultrasound treatment reduced the average particle size. However, the electrophoretic profiles of the control and ultrasound treated canola protein samples did not differ significantly. Based on the rheological measurements, all the emulsion gels were shear thinning and indicated elastic properties (G’>G’’). These results suggest that high intensity ultrasound treatment modified the structures of canola proteins enabling increased molecular interaction and enhancing particularly emulsion gel stability.