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Articles by Umar Santoso
Total Records ( 4 ) for Umar Santoso
  Dina Sugiyanti , Purnama Darmadji , Umar Santoso , Yudi Pranoto , Chairil Anwar and Sri Anggrahini
  Background and Objective: Low molecular weight chitosan (LWCS) was interestingly used because of it’s solubility and has good functional properties like antioxidant and antibacterial activity. This study aimed to evaluate antioxidant and antibacterial activity of chitosan and low molecular weight chitosan. Materials and Methods: Low molecular weight chitosan was obtained by physical and chemical hydrolysis using steam explosion process with steam pressure at 6 bar, temperature at 160°C and concentration of phosphotungstic acid at 0.1% w/v. The antioxidant activity was confirmed by radical DPPH scavenging activity, chelating metal ion value, inhibitory lipid peroxidation and antibacterial activity was confirmed by diffusion methods. Results: LWCS had antioxidant activity higher than native chitosan on radical scavenging, chelating ion value and inhibition of lipid peroxidation. LWCS had higher inhibitory effect as antibacterial than native chitosan against tested bacteria, there were Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Streptococcus aureus and Bacillus subtilis. Conclusion: It was concluded that LWCS had more powerful antioxidant and antibacterial activity than native chitosan.
  Rossi Indiarto , Yudi Pranoto , Umar Santoso and Supriyanto
  Background and Objective: The content of polyphenols in cacao beans can be modified during the processing of cacao. This study aimed to obtain the fraction of cacao bean extract polyphenols with the highest antioxidant activity and bioactive compounds profile of extracts and their fractions on cacao beans. Materials and Methods: The cacao beans (fermented for 5 days and unfermented) were blanched (5 min; 95°C), followed with defatted, freeze-dried and extracted uses 80% ethanol solvent. The extract obtained was then fractionated using n-hexane, chloroform, ethyl acetate, n-butanol and aqueous. Extracts and fractions obtained are calculated for yield, total polyphenol uses Folin-ciocalteu reagent, total flavonoid uses AlCl3, antioxidant activity uses DPPH and FRAP methods, functional group uses fourier transform infrared spectroscopy (FTIR) and polyphenol compound profiles uses UHPLC-MS/MS. Results: The results showed that the aqueous fraction had the highest yield but lowest chemical content and antioxidant activity. The unfermented cacao beans extract undergoing fractionation using ethyl acetate showed polyphenol content, flavonoids, DPPH free radical scavenging activity and highest ferric reducing activity. The FTIR analysis showed that the cacao bean extract and its fractions had O-H, C-H, C=O, C=C and C-O-C functional groups. Cacao beans extracts and ethyl acetate fractions were dominated by procyanidin compounds, especially dimer B2. Cacao bean fermentation caused a decrease in procyanidin compounds (monomer to nonamer) and alkaloids (theobromine and caffeine). Conclusion: Unfermented cacao bean extraction is then followed by fractionation with ethyl acetate solvent, obtained the fraction with highest chemical and antioxidant activity.
  Dina Sugiyanti , Purnama Darmadji , Sri Anggrahini , Chairil Anwar and Umar Santoso
  Background and Objective: Shrimp shell waste and crab shell waste are causes of environmental pollution and chemical methods can be used to process this waste into chitosan. Chitosan is the second largest natural biopolymer after cellulose and has many applications in food and health products. The aim of this research was to investigate the potential of Tambak Lorok shrimp shell and crab shell waste as an alternative raw material for chitosan production. Materials and Methods: Chitosan was prepared by chemically treating shell waste from shrimp in the Penaeidae rafinesque family and shell waste from crab in the Portunidae family from Tambak Lorok, Indonesia. The chemical structure of chitosan was confirmed by infrared spectroscopy, oswald viscometry and scanning electron microscopy. Results: The isolated chitosan from shrimp shell waste showed an 89.6% degree of deacetylation, a 64% degree of crystallinity and a 557 kDa molecular weight. The isolated chitosan from crab shell waste showed an 82.1% degree of deacetylation, an 81% degree of crystallinity and a 690 kDa molecular weight. Chitosan from both shrimp shell waste and crab shell waste had a porous and fibril-like structure. Conclusion: It was concluded that shrimp shell waste and crab shell waste are potential alternative raw materials for chitosan production.
  Rossi Indiarto , Yudi Pranoto , Umar Santoso and Supriyanto
  Background and Objective: The activity of the polyphenol oxidase enzyme during fermentation and drying causes a decrease in the polyphenol and flavonoid content of cacao beans. Blanching is important to inactivate the enzyme. This study aimed to evaluate the physicochemical properties and antioxidant activity of cacao bean extract in order to obtain a polyphenol-rich cacao extract. Materials and Methods: Unfermented and fermented cacao beans were blanched using water at 95°C ±2°C for 1, 3, 5 and 7 min. The process was then followed with drying and defatting using n-hexane and completed with extraction of polyphenol compounds using 80% ethanol. The blanched cacao beans were analyzed in terms of polyphenol oxidase enzyme activity and color, while the extracts of dried cacao beans were analyzed in terms of the relative activity of polyphenol oxidase, color, total polyphenol content, total flavonoid content, radical scavenging activity using DPPH, ferrous ion (Fe2+) chelating activity and the presence of functional groups using fourier transform infrared (FTIR). Results: Blanching unfermented cacao beans at 95°C for 5 min reduced the relative activity of polyphenol oxidase by >99%, maintained the purple color of the unfermented cacao beans and produced the highest content of polyphenols and flavonoids. Five minute blanching also increased antioxidant activity compared to the activity of unblanched cacao beans. The process of fermentation and hot air drying had a significant effect (p<0.05) on the decrease of polyphenols and the associated DPPH antioxidant activity in cacao beans. However, there was no effect (p>0.05) on Fe2+ chelating activity in unblanched cacao beans. Total polyphenol and flavonoid contents were strongly correlated with DPPH antioxidant activity but were not correlated with Fe2+ chelating activity. Conclusion: Blanching unfermented cacao beans with hot water for 5 min at 95°C was shown to increase the free radical scavenging activity by deactivating the polyphenol oxidase enzyme and thereby increasing the total polyphenol content.
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