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Articles by Sri Raharjo
Total Records ( 5 ) for Sri Raharjo
  Siti A. Budhiyanti , Sri Raharjo , Djagal W. Marseno and Iwan Y.B. Lelana
  The objective of the study was to isolate phenolic compound from the Sargassum hystrix crude extract by sequential solvent extraction using ethyl acetate, dichloromethane and butanol. In vitro antioxidant activity of fractionated cytoplasmic and membrane bound extracts were investigated. In addition to total phenolic content, the antioxidant activity were studied using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, metal chelating ability and Singlet Oxygen Quenching (SOQ) activity. Singlet oxygen quenching activity was examined using linoleic acid as substrate, containing 100 ppm erythrosine as a photosensitizer. The results showed that the membrane bound fractions had higher total phenolic compound, radical scavenging activity, ferrous ion-chelating ability and singlet oxygen quenching activity than cytoplasmic fractions (p<0.05). Among the eight fractions from membrane bound and cytoplasmic extracts isolated by differential solvent extraction, aqueous and butanol fractions of membrane bound extracts showed the highest DPPH radical scavenging, metal chelating ability and singlet oxygen quenching activity. The IC50 and metal chelating activity of aqueous fractions were 0.27±0.02 mg mL-1 and 51.53±6.63%, respectively and butanol fractions were 0.33±0.03 mg mL-1 and 44.75±3.33%, respectively. The butanol and aqueous fractions could act as SOQ at 75 ppm and 80 ppm, respectively. These results suggested that butanol and aqueous fractions were the most potent radical scavenger, metal chelator and singlet oxygen quencher.
  Ita Zuraida , Sri Raharjo , Pudji Hastuti and Retno Indrati
  Background and Objective: Differences in gelling properties may be attributed to the chemical composition and setting conditions at a particular temperature employed during the formation of surimi gels. The aim of this study was to investigate the chemical composition and effect of setting condition on the gel properties of surimi prepared from Clarias gariepinus (local name "lele dumbo"). Materials and Methods: Kamaboko gel was prepared by incubating the surimi sol at 35°C prior to heating at 90°C, while directly heated gel was prepared by heating the sol at 90°C. Data were subjected to analysis with a one-way ANOVA for comparison of means at a 5% level of significance. Results: The myofibrillar and sarcoplasmic protein contents were 16.27±0.23 and 2.02±0.06 mg N g–1 surimi, respectively. About 40% of transglutaminase activity was retained in the final surimi. Kamaboko gel showed higher gel strength, hardness and springiness when compared with directly heated gel. However, it had a lower expressible moisture content. Both surimi gels showed no significant difference in the whiteness parameter. Electrophoretic patterns indicated that although myosin heavy chain may undergo polymerisation in both, kamaboko gel and directly heated gel, the extent of polymerisation may be greater in kamaboko gel. Conclusion: The two-step heating involving setting of surimi sol at 35°C prior to heating at 90°C could enhance gel properties of lele dumbo surimi.
  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.
  Ita Zuraida , Sri Raharjo , Pudji Hastuti and Retno Indrati
  Background and Objective: The properties of surimi gel are influenced by the fish species used to generate the gel, their chemical compositions and the endogenous enzymatic activity in fish muscle. The aim of this research was to investigate the potential of Clarias gariepinus (local name "lele dumbo") as an alternative raw material for surimi production based on proximate composition, amino acid profile, protein composition and transglutaminase (TGase) and protease activity. Materials and Methods: This study used lele dumbo muscle as the raw material. The chemical properties of proximate composition, amino acid profile, protein composition and endogenous enzyme activity of the sample were determined using standard methods with three replicates. The results were presented as the means±standard deviation. Results: The moisture, ash, crude protein and crude fat content of fish muscle were 73.01±0.05, 0.78±0.02, 16.08±0.03 and 2.03±0.05%, respectively. The lele dumbo muscle has glutamine and lysine residues that can support TGase activity. Myofibrillar proteins were found as the major protein compounds in the fish muscle (16.57±0.03 mgN g–1 muscle) and the sarcoplasmic and stromal protein contents were lower, 4.38±0.03 and 0.71±0.05 mgN g–1 muscle, respectively. The TGase activity of the fish muscle was 0.18 U mL–1 (ΔAbs. = 0.21), which was higher than the protease activity (ΔAbs. = 0.10). Conclusion: Lele dumbo is a potential alternative raw material for surimi production.
  Siti Tamaroh , Sri Raharjo , Agnes Murdiati and Sri Anggrahini
  Background and Objective: Purple yam (Dioscorea alata L.) is a potential source of natural antioxidants due to its relatively high anthocyanin content. Anthocyanin is a natural source of antioxidants, acting as a free radical scavenger with a role in aging, cancer and degenerative illness prevention. Using a variety of solvents and acids, this study aimed to extract purple yam flour anthocyanins with high antioxidant activities. Methodology: Anthocyanins were extracted using methanol and ethanol-based solvents that were acidified with hydrochloric acid (HCl), citric acid or tartaric acid. The resulting extracts were assayed for anthocyanin and total phenolic contents, antioxidant activity (expressed as % radical-scavenger activity [%RSA]) and ferric reducing antioxidant power (FRAP). All data were analyzed using one-way analysis of variance. The differences were analyzed using Duncan’s multiple range test. The p<0.05 was considered significant. Pearson’s correlation coefficient analysis among anthocyanins, total phenolics contents and antioxidant activities were calculated using Microsoft Excel, 2007. Results: Results showed that the methanol/HCl (MeH) solvent could be used to extract anthocyanin from purple yam flour more thoroughly than other solvents. Total phenolic contents were not significantly different between MeH and methanol/tartaric acid (MeT) extracts (5.18 mg GA/100 g extract). Antioxidant activities of MeH and MeT anthocyanin extracts were not significantly different (69.87% RSA and FRAP of 50.27 μmol ε ferro L–1). Anthocyanin and total phenol contents correlated significantly with RSA and FRAP. Conclusion: This study suggested that anthocyanins and phenols purple yam flour are an abundant natural antioxidant sources, while the best solvent for the extraction was an acidified polar solvent.
 
 
 
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