Judul: Karakteristik Whey Kefir dan Aktivitasnya terhadap Penghambatan Angiotensin Converting Enzyme (ACE)
Abstrak: Whey is by product of cheese process that could be reached 80% of milk as cheese raw material. Whey contain the high of organic matter that could be potential to be exploited. Microbial fermentation by kefir grain can be used to utilize the whey. Bacteria and yeasts are growth simultaneously in kefir grain. Milk based fermentation product may contain bioactive peptides as functional foods, such as antihypertensive. This bioactive peptide could inhibit the angiotensin converting enzyme (ACE) activity, an enzyme that plays a role in the Renin Angiotensin Aldosterone system as a function of blood pressure regulation in human body. This research was conducted to evaluate the characteristic of whey based kefir product and its activity to inhibit the ACE. Kefir was produced by many type of whey as a treatment, SK : skim milk based kefir (control); WK : gouda cheese whey based kefir; and WKB : commercial whey powder based kefir, in three replication. Kefirs were evaluated for physical and chemical properties (pH, total titratable acidity, viscosity, protein, fat, lactose, and alcohol), microbiological (Lactic acid bacteria and yeast population), peptide concentration, ACE inhibition, IC50 and Inhibition Efficiency Ratio (IER). Data were analyzed by ANOVA, and continued by multiple comparison tests using Tukey’s HSD method. The results showed that the types of whey used for kefir productions significantly affected the physical and chemical characteristic of the products (P<0.05). Characteristics of whey kefir products were complaid to the CODEX STAN 234-2003 standards. Total lactic acid bacteria and yeast population of the products were not significantly different among whey types (P>0.05). The peptide concentration and ACE inhibitor activity of WK was 1.54 ± 0.02 mg/ml and 73.07 ± 0.91 % respectively. The values were significantly higher (P<0.05) than that of the control and WKB. IC50 of WK was 0.83 ± 0.02 mg/ml, significantly lower than that of control (1.05 ± 0.01 mg/ml) and WKB (0.96 ± 0.01 mg/ml). IER of WK was (47.35 ± 0.09 % per mg/ml), not significantly different (P>0.05) compared with control (47.19 ± 0.09 % per mg/ml) but significantly higher (P<0.05) than that of WKB (45.75 ± 0.18 % per mg/ml). General organoleptic test shows that the type of whey significantly affected (P<0.05) the panelist preferences on the sensory characteristic of whey kefir products. General sensory test result of WK was lower than that of SK but higher than that of WKB. Based on the plot of the intensity of sensory attributes, WK was in general between SK and WKB. The sensory properties that dominate the whey kefir product were specific kefir flavor, sour, compact and viscous texture. It was concluded that whey could be utilized for whey kefir production. Whey kefir has capability to be peptide bioactive sources for antihypertention agent. Whey kefir made from the Gouda cheese whey showed the higher ACE inhibitor activity than that of kefir based from commercial whey. Process optimization is necessary to meet the consumer preferences. The type of ACE inhibitor bioactive peptide in whey kefir product is also need to be further investigated.
Keyword: 

Judul: Production and Characterization of Bioactive Peptides From Whey By-Products Tofu Production
Abstrak: Tahu merupakan suatu produk yang dihasilkan dari proses pembentukan curd susu kedelai. Proses pembentukan tahu akan menghasilkan produk samping yaitu ampas tahu (padatan) dan whey tahu (cairan). Whey tahu merupakan suatu cairan bening berwarna kuning yang dihasilkan dari proses penyaringan dan pengepresan curd susu kedelai. Whey tahu memiliki kandungan seperti gula sederhana, protein (peptida dan asam amino) mineral dan komponen antioksidan. Tujuan penelitian ini adalah untuk mengkarakterisasi sifat fungsional peptida bioaktif dari whey protein tahu. Sampel yang dihasilkan dari penyaringan Whatman 3 diuji karakteristik derajat keasaman (pH) dan pengukuran kandungan protein, sementara profil protein dikarakterisasi dengan metode elektroforesis SDS- PAGE. Selain itu, permeate disaring menggunakan membran ultrafiltrasi 30, 10 dan 5 kDa cut-off. Filtrat yang sesuai dianalisis, ditinjau dari aktivitas antioksidan, kandungan isoflavon dan aktivitas penghambatan ACE. Whey tahu memiliki pH 3,14, kandungan protein kasar 2g/100 g sampel, kandungan protein terlarut 1,47 mg/mL. Pemisahan pita protein menggunakan SDS-PAGE menunjukkan bahwa peptida dominan yang ada dalam whey tahu memiliki berat molekul dibawah 18 kDa. Penggunaan membran ultrafiltrasi dapat meningkatkan bioaktivitas sampel. Filtrat yang dihasilkan dari membran yang paling kecil (5 kDa) memiliki aktivitas tertinggi terhadap aktivitas antioksidan, kandungan isoflavon dan aktivitas penghambat ACE., Tofu is a product produced from the process of curd formation of soy milk. The process of tofu formation will produce byproducts namely tofu pulp (solids) and whey (liquid). Tofu whey is a clear yellow liquid produced from the process of filtering and pressing soy milk curd. Tofu whey has content such as simple sugars, proteins (peptides and amino acids) minerals, and antioxidant components. This research aimed to characterize the functional properties of bioactive peptides from whey protein of tofu. The permeate resulted from Whatman 3 filtration was subject to the acidity (pH) and protein content measurement, while its protein profile was characterized by electrophoresis method of SDS-PAGE. Additionally, this permeate was futher sieved using ultrafiltration membranes with 30, 10 and 5 kDa cut-off. The corresponding filtrates were analyzed, in terms of antioxidant activity, isoflavone content and ACE inhibitor activity. The tofu whey had pH of 3.14, crude protein compound of 2 g/100 g sampel, and dissolved protein content of 1.47mg / mL. The separation of protein bands using SDS-PAGE showed that the dominant peptides present in tofu whey were having molecular weight below 18 kDa. The use of ultrafiltration membranes could increase the bioactivity of permeates. The filtrate resulted from the smallest membrane cut-off (i.e., 5 kDa) had higher antioxidant activity, isoflavone content and ACE inhibitory activity.
Keyword: ACE inhibitor, antioxidant, isoflavone, bioactive peptides, whey

Judul: Teknik penentuan posisi bintang berdasarkan pelat foto overlapping
Abstrak: Bintang adalah salah satu objek langit yang menarik untuk diamati. Untuk itu, pengetahuan tentang posisi bintang sangat diperlukan. Posisi bintang di langit dapat dihitung melalui foto bintang. Fotografi astronomi atau astrometri merupakan ilmu yang mempelajari metode untuk menentukan posisi bendabenda langit seperti bintang berdasarkan pelat foto (Kamp, 1967). Sebuah pelat foto berisi citra bintang-bintang yang sudah diketahui posisinya berdasarkan katalog dan citra bintang-bintang yang belum diketahui posisinya. Posisi bintang yang ada di katalog dinyatakan dengan (a,3). Bintang yang belum diketahui posisinya lebih banyak jumlahnya daripada bintang yang sudah diketahui posisinya. Citra bintang pada pelat foto berupa sebuah titik dalam bentuk tetap. Posisinya pada pelat merupakan hasil pengukuran pada bidang kartesius dan dinyatakan dengan (1;,fl). Hasil pengukuran tersebut kemudian direduksi menjadi koordinat terukur (x,y). Hubungan antara (a,3) dan (x,y) didekati dengan sebuah deret dengan konstanta-konsranta deret merupakan konstanta pelat. Nilai konstanta pelat diperoleh dengan menggabungkan hasil pengukuran posisi bintang pada masing-masing pelat menjadi sebuah persamaan normal (Jefferys, 1963). Hasil akhir dari gugus persamaan normal tersebut dijabarkan dalam bentuk nOlasi matriks partisi dan berupa sebuah sistem persamaan linier Ax = b di mana A adalah matriks jarang, dan x merupakan konstanta pelar yang akan dicari nilainya. Untuk menyelesaikan sistem persamaan linier terse but digunakan metode transformasi given. Konstanta pelat yang sudah diperoleh dengan menyelesaikan sistem persamaan linier di atas, kemudian disubtitusi ke sebuah persamaan untuk memperoleh posisi bintang yang tidak tercantum dalam katalog. .
Keyword: