Browsing by Subject "idätys"
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(2012)Folate is a water-soluble vitamin that belongs to the vitamin B group. The most important function of folate is to participate in C1 metabolism, and folate deficiency can lead to megaloblastic anaemia, neural-tube defects or coronary diseases. In Finland the folate fortification of food products is not mandatory and the intake of folate is still too low. Based on previous studies, blue lupin (Lupinus angustifolius) seems to be a good source of folate, especially the Haags Blaue variety, which has shown to be suitable for cultivation under Finnish environmental conditions. The aim of this research was to study if the folate concentration of blue lupin could be increased with germination and fermentation. In addition, the purpose was to examine how these bioprocessing methods would affect vitamer distribution of folates. Three germination experiments were performed, two with seeds that were soaked overnight in water and one with seeds that were soaked in lactic acid solution. The duration was four or five days and the samples were collected daily. The fermentation experiment was performed with kernel flour from non-germinated seeds and kernel flour from seeds that were germinated for two days. The synthesis of folate was studied using two microbes: Streptococcus thermophilus and Saccharomyces cerevisiae. The fermentation with S. cerevisiae yeast was made both with and without glucose addition. Samples were taken at 0 and 24 h. Total folate concentrations of samples were analysed with a microbiological method and the vitamers were analysed with an ultra-high-performance liquid chromatography method (UPLC). The folate concentration of seeds increased 2-fold by germination. The proportion of 5-methyltetrahydrofolate increased significantly during germination, from 60 % in nongerminated kernel flour to 77–88 % in germinated dehulled seeds. S. thermophilus did not produce folates in lupin flours. The folate content of non-germinated flour was increased 1.8-fold by yeast fermentation between 0 and 24 h, and yeast needed the glucose addition. However, glucose addition did not have an impact on folate concentrations of kernel flour from germinated seeds. Germination significantly increased the folate content of lupin seeds, and the greatest proportion of folates were stable vitamers. Stability of vitamers is important for the folates of food products thus germination of lupin seeds appears to be an interesting processing method. On the basis of the fermentation experiment, S. cerevisiae is a promising folate producing microbe when using lupin flour as a matrix. The fermentation experiment should still be repeated and performed using sterilised flour so that the actual production of folate by S. cerevisiae could be studied.
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(2012)The literature review focused on the proteins and insoluble fibre, ?-(1->4)-galactan, of blue lupin seed and how they degrade during germination. The review also dealt with the food applications of lupins and the harmful substances of lupins: allergens and ?-galactosides. The object of the experimental study was to determine the peptidase activities in the blue lupin seeds at the different stages of germination, classify the peptidases in the seeds and investigate the changes occuring in the proteins during germination and fermentation. The percentage of the water-soluble protein in the seeds was also determined. Blue lupin seeds were soaked in water over night and were germinated in the dark (15 ° C, RH 100 %). Peptidase activities were determined spectrofotometrically using azo-casein as a substrate. Class-specific peptidase-inhibitors (Pepstatin A, PMSF, E-64 and O-FEN) were used for classification of peptidases. Lactobacillus brevis and Lactobacillus rhamnosus were used in the fermentations (35 °C, 24 h) as well as baking yeast. The changes which occured in the proteins during germination and fermentation were investigated by electrophoresis (SDS-PAGE). The Dumas method was used to determine the percentage of the water-soluble protein in the extracts composed of soaked and germinated (2 day) seeds. Peptidase activities increased until the second day of germination and then remained constant until the fourth day. Serine- and aspartic peptidases were identified by inhibitor tests but not cysteine peptidases, even though cysteine peptidases have been previously known to break down legume proteins during germination. The cysteine peptidase inhibitor, E-64, used in this study has been observed earlier to inhibit cysteine peptidases belonging to papain family but not to legumain family. Proteins degraded slightly when the germination continued 4 days, and the degradation continued further during the fermentations. Large polypeptides (MW 45–100 kDa) mainly degraded during germination and fermentation. In addition, 17 kDa polypeptides degraded during fermentation. Possible 20 kDa hydrolysis products also formed during fermentation. The degradation of proteins in fermentations was more efficient when seeds germinated for 2 days were used compared to ungerminated seeds. The content of the water-soluble protein in the soaked seeds and the seeds germinated for 2 days varied between 35–96 %, and the content increased markedly when the pH of the extraction solvent increased from 6 to between 7.5–9.0. Thus the alkalinity of the extraction solution changed the structure of the storage seed proteins to more water-soluble form. The peptidase activity of germinated blue lupin could be applied in varied fermentation processes. The storage proteins of blue lupin were extremely water-soluble, so this discovery could be utilised for manufacturing substitutes for dairy products.
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