Browsing by Author "Byaruhanga, Yusuf B."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Physicochemical Characteristics of Yam Bean (Pachyrhizus erosus) Seed Proteins
    (Journal of Food Research, 2014) Kisambira, Abbas; Muyonga, John H.; Byaruhanga, Yusuf B.; Tukamuhabwa, Phinehas; Tumwegamire, Silver; Gruenberg, Wolfgang
    This study sought to determine the physicochemical and functional properties of yam bean (Pachyrhizus erosus) seed proteins. Pachyrhizus erosus seeds from two accessions (UYB 06 and UYB 07) were milled into flours and then defatted. A portion of the defatted flour was used for production of protein isolates and protein fractions. The physicochemical and functional properties, in vitro digestibility and electrophoretic pattern of the flour and protein isolate were determined. The results showed that albumins (53.3%) were the dominant protein fraction followed by globulins (18.7%), glutelins (8.8%) and prolamins (2.7%). Regarding functional properties, the Pachyrhizus erosus seed protein isolates exhibited 8% of least gelation concentration, water absorption capacity of 3.0 g g-1, oil absorption capacity of 0.8 g g-1, protein solubility of 81.0%, foaming capacity of 37.1%, foam stability of 73.8%, emulsion activity of 13.8% and emulsion stability of 9.2%. In vitro protein digestibility of the raw and cooked beans was 87.6% and 84.3%, respectively. The electrophoretic pattern of Pachyrhizus erosus protein showed major bands corresponding to molecular weight 13.3, 15, 29.8, 54.4 and above 84.7 kDa. The results, suggest that Pachyrhizus erosus seed protein has potential for use in both food and non-food applications such as films and coating.
  • Thumbnail Image
    Item
    Production of organic flavor compounds by dominant lactic acid bacteria and yeasts from Obushera, a traditional sorghum malt fermented beverage
    (Food science & nutrition, 2017) Mukisa, Ivan M.; Byaruhanga, Yusuf B.; Muyanja, Charles M. B. K.; Langsrud, Thor; Narvhus, Judith A.
    Single and mixed starter cultures of lactic acid bacteria (LAB): Weissella confusa MNC20, Lactobacillus plantarum MNC21, Lactococcus lactis MNC24 and Lactobacillus fermentum MNC34 and yeasts: Issatchenkia orientalis MNC20Y and Saccharomyces cerevisiae MNC21Y were used to produce Obushera, a fermented sorghum beverage. Microbial counts, pH, sugars, organic acids, and volatile compounds in starter culture and spontaneous fermentations were monitored during 48 hrs. Maximum counts of LAB (8.4–9.4 log cfu g−1) and yeasts (7.5 ± 0.1 cfu g−1) starter cultures were attained in 6–48 hrs. Weissella confusa, Lc. lactis, and Lb. fermentum showed possible acid sensitivity while I. orientalis produced surface films. LAB starter cultures and their combinations with S. cerevisiae lowered pH from 5.83 to <4.5 (3.50–4.13) in a shorter time (12 hrs) than spontaneous fermentations (24 hrs). Lactococcus lactis and W. confusa metabolized glucose the fastest (p < .05) during the first 6 hrs. Lactobacillus fermentum, Lb. plantarum, and S. cerevisiae utilized glucose and maltose concurrently. Lactobacillus plantarum and S. cerevisiae additionally utilized fructose. S. cerevisiae metabolized sugars the fastest (p < .05) during the first 12–24 hrs. Lactobacillus plantarum and W. confusa produced the highest (p < .05) amounts of lactate (5.43 g kg−1) and diacetyl (9.5 mg kg−1), respectively. LAB also produced acetate, ethanol, acetaldehyde, acetone, and acetoin. Coculturing LAB with S. cerevisiae reduced (p < .05) lactate and diacetyl yield. Yeasts produced high amounts of acetaldehyde and methyl alcohols. Issatchenkia orientalis produced higher (p < .05) amounts of 2-methy- 1- propanol and 3-methyl- 1- butanol than S. cerevisiae. Combinations of LAB with S. cerevisiae produced a profile flavor compounds close to that of spontaneously fermented Obushera. These combinations can be adopted for controlled fermentation of Obushera and related fermented cereal products.