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Articles by Tyas Utami
Total Records ( 4 ) for Tyas Utami
  Rita Khairina , Tyas Utami , Sri Raharjo and Muhammad Nur Cahyanto
  Background and Objective: Ronto is a traditional Indonesian fermented shrimp product; however, there are very few reports on how its properties change during fermentation. The aim of this study was to study the changes in sensory, physicochemical and microbiological properties of ronto during fermentation. Materials and Methods: Shrimp (Acetes japonicus) was mixed with salt and rice to give a mixture that was 11.5% salt and 20% rice. The mixture was put into plastic bottles and incubated at room temperature for 18 days. Samples were taken after every 2 days and sensory, physicochemical and microbiological properties were analyzed. Results: It was found that the fermented shrimp developed a sour, savory flavor and bright pink color after 8 days of fermentation, both of which became stronger after 12 days. After 14 days of fermentation, the texture of the shrimp gradually became that of a porridge-like paste. The acidity of the fermented shrimp increased during fermentation, after 12 days of fermentation, the pH had decreased from 8.3-4.8. The total volatile bases increased from 25-150 mg N/100 g over 18 days of fermentation. Lactic acid, proteolytic and amylolytic bacteria were involved in the fermentation process. The concentrations of these three bacteria increased during the early phases of fermentation and decreased in the later phases. Conclusion: Ronto fermentation ended after 14 days when the color of the fermented material became bright pink and when it had developed a strong, sour and savory flavor. That product had a lightness (53.11), a redness (11.72), a yellowness (15.68), a pH (4.8) and the texture of porridge-like paste and was relatively low in total volatile bases.
  Maherawati , Muhammad Nur Cahyanto , Yudi Pranoto and Tyas Utami
  Background and Objective: A variable amount of residual cyanide can still be found in processed cassava products, indicating that all of the linamarin in cassava cannot be hydrolysis. Linamarin and its enzyme, linamarase, are located in different cellular locations, therefore, disruption of the cell wall by cellulose could provide contact between linamarin and linamarase. The objective of this study was to improve linamarin hydrolysis by endogenous linamarase in cassava slurry using various concentrations of cellulases. Methodology: Cellulases from Celluclast® at concentrations of 0.075 filter paper unit (FPU) mL–1, 0.015 and 0.3 FPU mL–1 were added into cassava slurry and then incubated at 50°C for 24 h. During incubation, the reducing sugar, starch and hydrogen cyanide (HCN) contents were analysed and microscopic examination was conducted. Results: The reducing sugar content increased at all enzyme loadings, indicating that cellulose hydrolysis occurred. The starch content increased to 15.72 g/100 mL slurry at the highest enzyme loading. Rupture of the cassava cell wall was confirmed by light microscopy and scanning electron microscopy, which showed that the cell wall was damaged and starch granules were freed from the cell. Cell wall degradation allowed linamarin to make contact with endogenous linamarase and produced HCN, which increased at all enzyme loadings. The pattern of increasing HCN content was in accordance with the endogenous linamarase activity. Conclusion: The addition of cellulases increased linamarin hydrolysis in cassava slurry up to 79%. This methods can reduce the cyanide residue in cassava food products.
  Tanwirul Millati , Yudi Pranoto , Tyas Utami and Nursigit Bintoro
  Background and Objective: Cooked freshly harvested rice has high starch digestibility and a high glycemic index. This study aimed to examine the effect of the temperature and duration of accelerated aging on the physicochemical properties of freshly harvested rice, including in vitro starch digestibility and the estimated glycemic index of cooked rice. Materials and Methods: The rice used was freshly harvested IR 64 variety with 27.36±0.73% moisture content. The accelerated aging process was conducted at various temperatures and durations, namely, room temperature (24-30°C), 40, 50, or 60°C and 2, 4 or 6 days. The parameters quantified were free fatty acid levels, amylose content, thermal and pasting properties, starch digestibility and estimated glycemic index of cooked rice. Results: Free fatty acids, amylose-lipid complexes and thermal properties increase during accelerated aging treatment. The pasting properties increased at 40°C, while at 60°C, there was a slight decrease in all properties except for the pasting temperature, which increased. The starch digestibility and estimated glycemic index decreased and the lowest values were obtained from accelerated aging at 40°C for 4 days, which was not significantly different from 60°C for 4 days, with estimated glycemic index values of 68.61 and 69.82, respectively. Conclusion: The accelerated aging of freshly harvested rice reduced starch digestibility and the estimated glycemic index of cooked rice. The best temperature and time for reducing the starch digestibility and changing the estimated glycemic index of cooked rice from the high to medium category were 40°C and 4 days.
  Isti Handayani , Tyas Utami , Chusnul Hidayat and Endang Sutriswati Rahayu
  Background: Lactobacillus plantarum Dad-13 is a probiotic lactic acid bacteria strain that produces uricase for reducing uric acid. Objective: The aim of study was to evaluate the stability of intracellular uricase produced by L. plantarum Dad-13 in the gastrointestinal system and to enhance the production of this enzyme. Materials and Methods: Lactobacillus plantarum Dad-13 was grown on Peptone Glucose Yeast extract (PGY) medium supplemented with uric acid as inducer. The stability of intracellular uricase was evaluated in the stomach and small intestine models. For enhancement of uricase production, L. plantarum was grown on variation of incubation time, uric acid concentration and temperature, while glucose residue, intracellular uric acid were used as the criteria of evaluation. Data were statistically analyzed by one way-ANOVA followed by DMRT. Results: The intracellular uricase of L. plantarum Dad-13 remained active in the gastrointestinal system. Uricase is an inducible enzyme produced when glucose residue limited in the medium. This bacteria uptake uric acid from the medium during growth and uricase activity was obtained at the optimum concentration of uric acid in the cell. A maximum uricase activity was reached at 0.15% uric acid concentration and 37°C for 22 h of incubation. Conclusion: Production of intracellular uricase produced by L. plantarum Dad-13 which have activity in gastrointestinal tract could be enhanced by optimum fermentation and make it applicable for hyperuricemia treatment.
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