Peat soil humin, obtained after the removal of fulvic and humic acid fractions according to the recommended procedure of the International Humic Substances Society (IHSS), has the ability to remove AuCl-4 ions from aqueous solution. The removal was greatest at medium acidity, which was equivalent to pH 2.0, and it was governed by two different processes, i.e. attachment onto un-ionized-COOH groups through hydrogen bonding and reduction to Au metal by the action of the-OH group. Purification of humin through repeated immersion and shaking in a mixed solution consisting of 0.1 M HCl and 0.05 M HF led to the abrupt increase in the-COOH contents from 386 mmol/kg to 2510 mmol/kg, while the content of total-OH functional groups remained relatively constant at values slightly higher than 3000 mmol/kg. The increase in-COOH content improved the removal of AuCl-4 ions from 23 mg/g to 27 mg/g, but it was unfortunately accompanied by a diminished reduction ability to Au metal. Hence, the role of the-COOH functional group in removing AuCl-4 ions through hydrogen bonding was more significant for the purified humin, while that of the-OH group in removing AuCl-4 ions through reduction to Au metal was better for the crude (unpurified) humin.

Abstrak. Flavonoid merupakan senyawa fenolik yang banyak diisolasi dari tanaman karena manfaatnya sebagai antioksidan, anti mikroba, dan antikanker. Sebagai antioksidan, flavonoid dapat menangkap radikal bebas yang dapat merusak sel tubuh. Oleh karena itu, kandungan total flavonoid (TFC) dan aktivitas antioksidan (IC50) ekstrak jamur Pleurotus ostreatus penting untuk diteliti. Flavonoid diekstrak menggunakan metode Microwave-Assisted Extraction (MAE) dengan variasi waktu ekstraksi (2, 3, dan 4 menit) dan variasi rasio antara jamur dan pelarut (1:30, 1:35, dan 1:40). Kandungan flavonoid dianalisis dengan metode kolorimetri menggunakan alumunium klorida, sedangkan aktivitas antioksidan ditentukan dengan metode DPPH. Hasil penelitian menunjukkan bahwa semakin lama waktu ekstraksi, semakin tinggi TFC dan aktivitas antioksidan. Kandungan flavonoid tertinggi diperoleh pada perlakuan waktu ekstraksi 4 menit dan rasio jamur:pelarut 1:30, yaitu sebesar 1,53 mg QE/ g dw dengan nilai IC50 sebesar 14,66 mg/ml. Flavonoid Content and Antioxidant Activity of Pleurotus ostreatus Extract Abstract. Flavonoids-phenolic substances- are isolated from plant due to their benefits as an antioxidant, an antimicrobial, and an anticancer. As an antioxidant, flavonoids can scavenge free radicals that damage body cells. In this study, the total flavonoid content (TFC) and its antioxidant activity (IC50) of Pleurotus ostreatus -an oyster mushroom- extract were investigated. The flavonoid was extracted by using Microwave-assisted Extraction (MAE) at different of extraction time (2, 3, and 4 minutes) and ratio of P.ostreatus and solvent (1:30, 1:35 and 1:40). The flavonoid contents were determined by alumunium chloride colorimetric method whereas the antioxidant activity was determined by DPPH method. The results revealed that the higher extraction time, the higher TFC and antioxidant activity, where the highest TFC was obtained at 4 minutes extraction with ratio of P.ostreatus and solvent of 1:30. The highest TFC of P.ostreatus extract was 1.53 mg QE/ g dw with antioxidant activity (IC50) of 14.66 mg/ml.

The effect of natural antibiotics Moringa oleifera seeds powder in cellulose acetate membranes as biofouling reducer agent was investigated. Mixed matrix membranes (MMM) were synthesized by adding 100 mesh M. oleifera seeds powder with variation of three concentrations (1 wt%, 2 wt%, and 3 wt%), into a mix polymer solution of CA (cellulose acetate) and two different solvents, i.e., DMF (dimethylformamide) and DMAc (dimethylacetamide). The synthesized membranes morphology was observed under scanning electron microscopy and from the images can be seen that the membranes made of DMAc formed rather large macrovoid as compared to DMF-based membranes. The microstructure affected the water flux through the membranes, in which the DMAc membranes provided a higher flux value and served as high-throughput microfiltration membranes. Antibacterial properties of MMM were tested using Escherichia coli adhesion onto membrane surfaces. The results showed that M. oleifera has been proven to eradicate E. coli activity on the membrane surfaces due to interaction between bacterial cells and phenolic compounds from M. oleifera, through absorption processes involving hydrogen bonds. two or more different properties of components combined, to achieve a better separation performance. In order to promote antifouling properties, some combination of functionalized fillers and polymer matrixes have been used, such as a combination of nanoparticles of anatase TiO 2 /polysulfone [10] and Ag-loaded graphene oxide/polyethersulfone [11]. Those combination were effective, however the use of metal components as fillers, e.g., silver particles, might be unsafe for membrane that is used for food processing application. The use of plant-based subtances, might provide a more reliable and safe anti-biofoulant, such as the utilization of cardanol [12]. In this study, a natural antibacterial M. oleifera seeds powder is evaluated to be employed as filler to the cellulose acetate polymer matrix to form anti-biofouling MMM.M. oleifera could be utilized against Gram positive and negative bacteria [13]. Recombinant protein inside M. oleifera seeds is able to agglomerate Gram positive and negative bacterial cells [14]. By its properties, Moringa seeds could potentially be used as for environmentally friendly antibiofouling, because these natural ingredients are not harmful, even if used in large quantities when compared with chemicals or metals that are commonly used as agents to reduce biofouling.As for polymeric matrix, cellulose acetate has been chosen due to some beneficial properties. Cellulose acetate has good properties as a membrane polymer for food processing due to renewable, biodegradable, biocompatible, non-toxic, and inexpensive subtances [15,16]. Cellulose acetate has relatively thermal and chemical stability [17], because cellulose has a rich of hydroxyl groups and it is able to form a strong hydrogen bonds that could not be separated easily [18]. Cellulose acetate are also extraordinary hydrophilic, which can be used for minimizing fouling on t...

ABSTRAKGula merah sebagai sukrosa diperoleh dari nira tebu yang diuapkan. Penguapan merupakan proses pengolahan bahan pangan yang umumnya digunakan pada pembuatan gula merah tebu, dimana proses ini menguapkan sebagian besar nira untuk menghasilkan produk yang kental (konsentrat). Penelitian ini bertujuan untuk mengkaji pengaruh penambahan natrium metabisulfit terhadap sifat fisik dan kimia gula merah tebu yang dihasilkan dari penggunaan vacuum evaporator, dan mengkaji pengaruh suhu pemasakan pada vacuum evaporator terhadap sifat fisik dan kimia gula merah tebu. Pemasakan gula dilakukan pada tekanan -700 mmHg di bawah tekanan atmosfir, dengan variasi suhu pemasakan 60, 70 dan 80 o C dan dengan penambahan natrium metabisulfit 0,1; 0,3 dan 0,5 g/l nira. Semakin besar penambahan natrium metabisulfit dalam pengolahan gula merah tebu, semakin tinggi kadar abu yang dihasilkan sedangkan intensitas warna hijau dan biru gula merah tebu semakin kecil. Semakin tinggi suhu pemasakan, semakin rendah kadar air, kadar abu, intensitas warna hijau dan biru gula merah tebu. Semakin tinggi suhu pemasakan, semakin tinggi tingkat kekerasan atau tekstur, tingkat kesukaan warna, rasa dan tekstur gula merah tebu. Berdasarkan analisis statistik, perlakuan suhu pemasakan berpengaruh terhadap kadar air, kadar abu dan gula reduksi gula merah tebu. Sedangkan perlakuan penambahan natrium metabisulfit berpengaruh terhadap kadar abu, gula reduksi dan total padatan tak terlarut pada gula merah tebu. Berdasarkan parameter sifat kimia, fisik, uji organoleptik dan persyaratan SNI gula merah tebu, penambahan natrium metabisulfit 0,3 g/l dan suhu pemasakan 80 o C dalam pengolahan nira tebu menjadi gula merah menunjukkan kualitas yang paling baik. Nilai masing-masing parameternya dari perlakuan terbaik sebagai berikut: parameter kimia dan fisik dengankadar air 8,97%, gula reduksi 7,96 %, kadar abu 2,65%, total padatan tak larut 0,60 %, nilai kekerasan 15,68 kg/cm 2 , parameter organoleptik denganwarna 5,50, rasa 5,04 dan tekstur 5,36.Kata kunci: Nira tebu, natrium metabisulfit, suhu, evaporator vakum, gula merah ABSTRACTBrown sugar as sucrose is derived from evaporated sugar cane molasses. Evaporation is the foodstuffs' process which is commonly used during the manufacture of sugar cane. This process evaporates the sugar cane molasses to produce concentrate. This research was aimed to assess the influence of sodium metabisulphite against physical and chemical properties of sugar cane using vacuum evaporator. In other hand, this reserach examined the influence of temperature on vacuum evaporator for chemical and physical properties of sugar cane. Sugar cooking was done at -700 mmHg below atmospheric pressure, with variations in heating temperature of 60, 70 and 80 o C, and with the addition of sodium metabisulphite 0.1; 0.3 and 0.5 g/l sugar cane molasses. The larger addition of sodium metabisulphite in the processing of sugar cane, the higher ash content generated while the green and blue colors of red sugar cane were getting smaller. The higher cooki...

The ultrafiltration membrane process is widely used for fruit juice clarification, yet the occurring of fouling promotes a decline in process efficiency. To reduce the fouling potential in the membrane application in food processing, the use of natural phenolic compounds extracted from cocoa pod husk is investigated. The cocoa pod husk extract (CPHE) was prepared in phenolic nanoparticles form and added into the polymer solution at varying concentrations of 0.5 wt%, 0.75 wt%, and 1.0 wt%, respectively. The composite membrane was made of a cellulose acetate polymer using DMF (dimethylformamide) and DMAc (dimethylacetamide) solvents. The highest permeability of 2.34 L m−2 h−1 bar−1 was achieved by 1.0 wt% CPHE/CA prepared with the DMAc solvent. CPHE was found to reduce the amount of Escherichia coli attached to the membranes by 90.5% and 70.8% for membranes prepared with DMF and DMAc, respectively. It is concluded that CPHE can be used to control biofouling in the membrane for food applications.

Kenikir (Cosmos caudatus) merupakan tumbuhan yang banyak terdapat di Indonesia. Selama ini kenikir hanya dimanfaatkan sebagai sayuran atau lalapan, padahal daun kenikir mempunyai kandungan kimia yang mempunyai sifat antioksidan, antibakteri, dan dapat digunakan sebagai obat. Senyawa fenolik merupakan salah satu senyawa dalam daun kenikir yang mempunyai sifat antioksidan. Antioksidan merupakan senyawa yang berpotensi untuk melawan oksidan berbahaya yang dapat merusak sel tubuh. Pada penelitian ini dilakukan ekstraksi senyawa fenolik daun kenikir dengan Pulse Electric Field (PEF). Proses ekstraksi dilakukan dengan variasi rasio bahan: pelarut yaitu 1:4, 1:6, dan 1:8, sedangkan waktu pemaparan PEF yang digunakan adalah 3, 6, 9, 12 detik. Hasil penelitian menunjukkan total fenol dan aktivitas antioksidan tertinggi didapatkan pada ekstraksi dengan rasio bahan:pelarut 1:8 selama 6 detik yaitu 5.87 mg GAE/g fw dan 70.74%

ABSTRAKPenelitian mengenai pengaruh suhu pemasakan dan kecepatan pengadukan terhadap kualitas gula merah tebu yang diolah dengan evaporator vakum tipe vertikal telah dilaksanakan. Gula merah tebu dihasilkan dari nira hijau yang telah dimurnikan dari pengotor dengan penambahan Ca(OH) 2 . Nira murni dimasak dengan variasi suhu pemasakan 60, 70, dan 80 o C, serta kecepatan pengadukan 200 dan 250 rpm. Gula merah tebu yang dihasilkan kemudian dianalisis warna, kadar air, kadar abu, sukrosa, uji organoleptik (uji mutu hedonik terhadap warna, rasa, tekstur / kekerasan). Hasil penelitian menunjukkan bahwa semakin tinggi suhu pemasakan semakin baik kualitas warna, rasa, dan tekstur (kekerasan) gula merah yang dihasilkan. Sementara pengaruh kecepatan pengadukan terhadap gula merah tebu, yaitu semakin tinggi kecepatan pengadukan, kadar air gula merah yang dihasilkan semakin rendah, sehingga tekstur (kekerasan) gula merah tebu yang dihasillkan semakin baik. Selain dipengaruhi oleh suhu pemasakan dan kecepatan pengadukan, kualitas gula merah dipengaruhi oleh kualitas nira dan proses penjernihan. Kualitas nira yang baik akan menghasilkan rendemen yang tinggi, kadar air yang rendah, kadar sukrosa yang tinggi, serta warna, rasa, dan tekstur yang baik. Hasil terbaik diperoleh pada gula merah tebu yang dihasilkan dengan suhu pemasakan 70 o C dan kecepatan pengadukan 250 rpm, yaitu diperoleh rendemen 8.23%, kadar sukrosa 75.37%, tekstur (kekerasan) 4.52 kg/cm 2 , dan warna gula merah yang cerah dan mempunyai intensitas yang tinggi.Kata kunci: nira tebu, evaporator vakum, gula merah, pengadukan, suhu pemasakan ABSTRACT Research of the effect of cooking temperature and stirring speed on the quality of brown

No abstract