PROPERTIES OF IMMOBILIZED LIPASE FROM Rhizopus delemar ON POLYPROPYLENE MEMBRANE = SIFAT-SIFAT ENZIM LIPASE AMOBIL DARI Rhizopus delemar DALAM MEMBRAN POLIPROPILEN

ABSTRACT Properties of Rhizopus delemar lipase immobilized on hydrophobic polypropylene membrane were studied by physical adsorption using various concentration of enzyme loading. The result shows that free fatty acid liberation was affected by the enzyme loading, which increased with the increasing enzyme loading. The maximum enzyme adsorption was achieved at 1.2 mg/cm2 membrane. The initial velocity of hydrolysis reaction seems not to be affected by the amount of enzyme bound. The immobilization efficiency was very high reaching more than 60 % at enzyme loading of 0.3 mg/cm2, although a suppression of efficiency was detected at higher loading. The immobilized lipase could hydrolyze 97 % olive oil after 72 h using 1 mg/cm2 of initial enzyme loading. The kinetic parameter indicated that the affinity of the enzyme to substrate was very low (Km = 183 mg/mI). The immobilized enzyme was very stable during storage at 4 °C with proximate half life 65 days. In addition, it maintains ability for subsequent reuses. The membrane can be regenerated by washing for fresh enzyme immobilization. Key words: lipase, Rhizopus delemar, immobilization, polypropylene, membran

Detection of Fish Freshness Using Immobilized ADP-ase and 5\u27-Nucleotidase on Polyacrylamide Gel

ABSTRACT The presence of ADP and IMP in the muscle of fish could be used as an indicator of its freshness. These metabolites could be detected enzymaticaly using ADPase and 51-nucleotidase. The aim of this research was to determine the presence of ADP and IMP in the muscle of fish qualitatively, using immobilized ADPase and 5\u27-nucleotidase on polyacrylamide gel. The results showed that in the non-immobilized form, ADPase has an optimum pH of 6 and stable at pH 5.5-10, while 5\u27-nucleotidase has two optima pH of 6.5 and 9 and it was stable at pH 7-10. Optimum temperature of ADPase and 5\u27-nucleotidase was 45 and 50°C, respectively. In the immobilized form, the activity of ADPase was optimum at pH 6 and it was still stable at pH 5.5 - 7.0 after storage at -20°Cfor 90 days, while 5\u27-nucleotidase was still stable at pH Z5-10 after storage at -20°C for 90 days. Both enzymes were more stable in frozen storage than that of chilled storage. Sensitivity of both enzymes to detect the fish freshness during storage was affected by the presence of free inorganic phosphate derived from other phosphate-containing metabolites. Key words : detection of fish freshness, , immobilized ADPase, immobilized 5\u27nucleotidase

Pengaruh penggunaan berbagai basa dan pati dalam pembuatan cincau

ABSTRACT Instant black cincau was prepared by the processing steps involving extraction of "janggelan" using alkaline solution, drying of the extract, and blending of the dried extract with starch. Various alkalines of different valence, i.e. NaOH, Mg(OH)2 and Ca(OH)2 at pH 10 were used to extract "janggelan" at the proportion of 50 g/100 ml of alkaline for 60 minutes at boiling condition. Arenga, sago, maize, mung bean, tapioca and soft rice starches were used to blend the dried extracts. The proportions of dried extracts used were at 1.5, 2.0, and 2.5 g per 7.5 g starch. Gels were prepared by boiling the blended stuffs in 250 ml water and allowed to cool to room temperature. The gels were characterized for breaking strength, elasticity and syneresis. The results indicated that the use of divalent alkaline gave higher strength, equal elasticity, and higher syneresis of the gels compared to that of monovalent alkaline. All the starches containing 20.6-47.1 % amylose, excluding soft rice starch, gave compact gels, but higher amylase did not always give stronger gels. The use of starch containing 11.9 % amylose did not form gel. The increase in proportion of dried extract to starch caused higher breaking strength, but lower elasticity and syneresis of the gels. Key words : alkaline, valence, extraction, "janggelan", instant black"cincau", physical characteristics, gel

Utilization of ATP and Its Derivatives as an Index of Freshness of Nila (Oreochromis niloticus) During Storage

ABSTRACT The role of a reliable and reproducible, index of fish freshness, is important. The objective of this research was to examine the utilisation of ATP and its derivatives (expressed as K-value) as an index offish freshness using Nila (Oreochromis niloticus) as a model of study. K-value is [(Inosine + Hypoxanthine) / (ATP + ADP + AMP + IMP + Inosine + Hypoxanthine)] x 100%. Live fish were killed, packed individually using polyethylene bag and stored at 4 and 28°C. At defined time, some fishes were examined their ATP and its breakdown products using a reverse phase HPLC system. The results showed that ATP, ADP and AMP were degraded rapidly and disappeared within 12 ho urs. Degradation of IMP in the samples stored at 4°C was slower than those of samples stored at 28°C. Interestingly, the accumulation of Inosine occurs only in the samples stored at 28°C while the accumulation of Hypoxanthine occurs only in the samples stored at 4"C. The data suggested that the activity of IMP-degrading enzyme (5\u27-nucleotidase) at 4"C was higher than that of Inosine-degrading enzyme, but at 28°C both enzymes have similar activities. Linear regression analysis between K-value and storage time showed that increasing rate of K-value or rate of the lowering freshness of samples stored at 28"C was 4 times higher than that of samples stored at 4°C. Limits offish acceptability (K-value 60%) of Nila stored at 28 and 4"C were reached at 12 and 72 hours, respectively. The results confirmed that K-value was the best as an index offish freshness compared with IMP, Inosine and Hypoxanthine and it could be used as an index of freshness of Nila (Oreochromis niloticus) during storage

A Simplified Method for Determination of Free Fatty Acids for Soluble and Immobilized Lipase Assay

ABSTRACT A simple and rapid method for determination of free fatty acids for soluble and immobilized lipase assay was developed. The free fatty acids could be determined within 10 min with less organic solvent used and the color developed was stable until 60 min. High correlation (r > 0.97) between fatty acids content (2 -10 pmole) and absorbance was observed for fatty acids with carbon number of 6 or higher. Hydrolysis activity of soluble and immobilized lipase could be measured with high sensitivity and reproducibility against incubation time and protein loading. The effect of various substrate concentrations and water against hydrolysis activity could also be measured. The method was suitable for routine analysis such as purification of lipase and continuous hydrolysis of fat and oil

Pengaruh Umur Panen Rumput Laut Eucheuma Cottonii Terhadap Sifat Fisik, Kimia Dan Fungsional Karagenan

The aim of this study was to evaluate the effect of different harvesting times of Eucheuma cottonii on both physical, chemical and functional properties of carrageenan. Seaweed Eucheuma cottonii was obtained from water territorial of Tablolong Kupang. The study was carried out into two steps. The first step was to investigate the effect of harvesting time of 30, 45, and 60 days after planting on physical and chemical properties of obtained carrageenan. The second step was to study the effect of functional properties of obtained carrageenan on viscocity and the stability of tomato sauce. The results showed that seaweed which was harvested in 45 days after planting has good physical and chemical properties of carrageenan in term of moisture 12.45 %; protein 5.03 %; extract ether 1.40 %; ash 21.29 %; carbohy- drate 72.28 %; sulphate 19.69 %; and crude extract 48.20 %. The obtained carrageenan at concentration of 1,5%, also give highest viscocity of 11.50-45 cps and gel strength of 0.8961-4.0709 kg/cm2. Further identification show that the obtained carrageenan produced was classified as kappa carrageenan and at 0,2 % (w/v) was able to stabilize tomato sauce up to 86 % and viscosity of 60 cps after 2 weeks of storage at room temperature

Pengaruh Umur Panen Rumput Laut Eucheuma cottonii terhadap Sifat Fisik, Kimia dan Fungsional Karagenan

The aim of this study was to evaluate the effect of different harvesting times of Eucheuma cottonii on both physical, chemical and functional properties of carrageenan. Seaweed Eucheuma cottonii was obtained from water territorial of Tablolong Kupang. The study was carried out into two steps. The first step was to investigate the effect of harvesting time of 30, 45, and 60 days after planting on physical and chemical properties of obtained carrageenan. The second step was to study the effect of functional properties of obtained carrageenan on viscocity and the stability of tomato sauce. The results showed that seaweed which was harvested in 45 days after planting has good physical and chemical properties of carrageenan in term of moisture 12.45 %; protein 5.03 %; extract ether 1.40 %; ash 21.29 %; carbohy- drate 72.28 %; sulphate 19.69 %; and crude extract 48.20 %. The obtained carrageenan at concentration of 1,5%, also give highest viscocity of 11.50-45 cps and gel strength of 0.8961-4.0709 kg/cm2. Further identification show that the obtained carrageenan produced was classified as kappa carrageenan and at 0,2 % (w/v) was able to stabilize tomato sauce up to 86 % and viscosity of 60 cps after 2 weeks of storage at room temperature.ABSTRAKTujuan penelitian adalah mengkaji sifat fisik dan kimia karagenan yang diperoleh dari rumput laut Eucheuma cot- tonii pada umur panen yang berbeda dari perairan Tablolong Kupang dan mengetahui sifat fungsionalnya sebagai stabilizer dan thickener dalam saos tomat. Penelitian diawali dengan menanam rumput laut pada interval tanam yang berbeda, sehingga pada saat panen yang bersamaan diperoleh rumput laut dengan umur yang berbeda yaitu 30, 45,60 hari. Tahap berikutnya adalah ekstraksi dan karakterisasi karaginan yang dihasilkan, kemudian aplikasi karaginan yang diperoleh untuk menjaga stabilitas viskositas saos tomat pada konsentrasi karagenan (0,1 %, 0,15 %, 0,2 % b/v). Hasil penelitian menunjukkan bahwa karagenan dengan kadar sulfat tertinggi (19,69%), rendemen terbanyak (48,20%), dan 3,6-anhidro galaktose unit terbanyak diperoleh dari rumput laut yang memiliki umur panen 45 hari, dengan kadar air 12,45 %; protein 5,03 %; lemak 1,40 %; abu 21,29 %, dan karbohidrat 72,28 %. Sifat fungsional yang dimi- liki antara lain viskositas 11,50-45 dps dan kekuatan gel 0,8961 – 4,0709 kg/cm2 pada konsentrasi karagenan 1,5 %. Hasil identifikasi gugus fungsi menunjukkan bahwa jenis karagenan yang dihasilkan adalah kappa. Karagenan dari rumput laut dengan umur panen 45 hari pada konsentrasi 0,2 % (b/v) dapat memberikan viskositas saos tomat sebesar60 dps dengan stabilitas 86 % setelah disimpan selama 2 minggu

Kinetika Pertumbuhan Mikrobia dan Kemunduran Mutu Bakso Berpelapis Edible Aktif Berbasis Pati Kimpul (Xanthosoma Sagittifolium) pada Berbagai Ketebalan

Quality deterioration of food material with active edible coated depends on product properties, environment andproperties of coating. Properties of coating are influenced by the type and amount of the basic constituent materials, plasticizers, and active coating ingredient. The objective of this research was to determine the kinetics of microbial growth, and quality deterioration of X. sagittifolium starch-based coated meatball with various thicknesses. The treatments tested in this study were thickness of edible coatings (0.43; 0.48; 0.53; 0.58 mm). Observation parameters were the number of microbes (total microbial, and Pseudomonas aeruginosa), protein content, TVB-N, water losses, and texture. The results showed that active edible coatings thickness significantly affected of microbes number, and TVB-N, but did not affect protein content, water losses, and meatball texture. Microbial growth (TPC and P. aeruginosa) changed exponentially with the rate of increase of 0.049 to 0.055 per hour for TPC and from 0.071 to 0.075 per hour for P. aeruginosa or 0.026 per mm.hour times the thickness. TVB-N content changed linearly with the rate of increase of 0.132 to 0.153 mg/100g.hour or 0.206 mg/100g.mm.hour times the thickness. X. sagittifolium starch-based active edible coating with potassium sorbate as active ingredient and 0.43 mm coating thickness could prolong meatball shelf life up to 4 times longer than control