Sabar

"Sabar.... sabar....", kata-kata ini yang sering kali dilontarkan oleh beberapa orang agar membuat hati sedikit lebih tenang. Kebetulan tadi pagi dalam kajian di kost baca wisma tetang bagaimana sabar dalam menghadapi sesuatu. Sampai pada berjalannya hari ini banyak sekali belajar tentang kesabaran yang langsung diberikan oleh Allah melalui beberapa orang.
Sangat sadar bahwa masih sangat banyak kekurangan dalam diri, sangat paham bahwa tidak pantas untuk berada diposisi sekarang, dan masih banyak yang harus dievaluasi. Banyak cacian, makian, sikap arogan dan tidak senang. Sangat senang sekali jika masih diingatkan, berarti masih ada orang yang mau peduli dan memperhatikan apa yang dilakukan. Tetapi, jika kita sebagai orang yang diberi kesempatan untuk berpendidikan lebih, apakah harus bersikap dan bertutur kata yang kurang baik? seharusnya kita lebih bisa bersikap lebih baik.
Belajar dari sikap sabar, saya harusnya berterimakasih kepada orang2 yang telah memberikan kesempatan kepada saya untuk bersabar. Untuk mengendalikan hawa nafsu dan control emosi. Belajar menjadi jiwa yang tenang, menanggapi sesuatu lebih bijak dan tepat. Karena hal-hal tersebut sangat sulit dilakukan.
Ini samasekali tidak sebanding dengan perjuangan Rasulullah yang begitu luar biasa dalam kesabaran. Menghadapi kaum kafir Quraisy yang tidak henti2nya mencibir, menghina dan memperlakukan Rasulullah tidak manusiawi, tetapi Rasulullah ttap sabar dan tak henti-hentinya menjalankan dakwah untuk seluruh umat manusia.

so...,,,keep calm....sabar,,,untuk kualitas hidupmu meningkat...:)

Ayo Nulis

"Belajar Menulis..."
Belajar menulis???!!!buat apa??kan kita sudah bisa nulis dari dulu....

Menulis sebenarnya adalah hal yang kurang terlalu saya suka karena tidak ada bakat menulis. Sudah beberapa kali mencoba menuliskan apapun yang sedang saya pikirkan tetapi sulit untuk menuangkannya. Tetapi dengan segala kondisi sekarang ini banyaksekali tuntutan untuk menulis. Sesekali, saya juga mendapatkan motivasi dari teman saya yang suka menulis untuk menuliskan apa saja dalam sarana ini.
Alhamdulillah, sekarang ini ghirrah untuk menuliskan tulisansudah ada, mungkin bisa dibaca orang dan punya manfaat, ya...meskipun sedikit setidaknya ada niat dan awalan untuk bisa menuliskan segala yang kita pikirkan, entah ringkasan kuliah, info update dan kajian yang bisa bermanfaat buat orang lain....

'lakukan apa yang kamu inginkan asal baik, tuliskan apa yang kamu pikirkan asal benar...'

Selamat Menulis Kawan...............

Mari melakukan hal yang bermanfaat....

Membaca...
Diskusi...........
Menulis...................

Let's to try it...!!!

miruku

The Scince of Technology Milk from Mr. Albaari......

The following topics will be covered in this section:

• Introduction
• Homogenization Mechanism
  • turbulence
  • cavitation
• Effect Of Homogenization
  • fat globule properties
  • surface layers

Introduction

Milk is an oil-in-water emulsion, with the fat globules dispersed in a continuous skimmilk phase. If raw milk were left to stand, however, the fat would rise and form a cream layer. Homogenization is a mechanical treatment of the fat globules in milk brought about by passing milk under high pressure through a tiny orifice, which results in a decrease in the average diameter and an increase in number and surface area, of the fat globules. The net result, from a practical view, is a much reduced tendency for creaming of fat globules. Three factors contribute to this enhanced stability of homogenized milk: a decrease in the mean diameter of the fat globules (a factor in Stokes Law), a decrease in the size distribution of the fat globules (causing the speed of rise to be similar for the majority of globules such that they don't tend to cluster during creaming), and an increase in density of the globules (bringing them closer to the continuous phase) oweing to the adsorption of a protein membrane. In addition, heat pasteurization breaks down the cryo-globulin complex, which tends to cluster fat globules causing them to rise.

Homogenization Mechanism

Auguste Gaulin's patent in 1899 consisted of a 3 piston pump in which product was forced through one or more hair like tubes under pressure. It was discovered that the size of fat globules produced were 500 to 600 times smaller than tubes. There have been over 100 patents since, all designed to produce smaller average particle size with expenditure of as little energy as possible. The homogenizer consists of a 3 cylinder positive piston pump (operates similar to car engine) and homogenizing valve. The pump is turned by electric motor through connecting rods and crankshaft. To understand the mechanism, consider a conventional homogenizing valve processing an emulsion such as milk at a flow rate of 20,000 l/hr. at 14 MPa (2100 psig). As it first enters the valve, liquid velocity is about 4 to 6 m/s. It then moves into the gap between the valve and the valve seat and its velocity is increased to 120 meter/sec in about 0.2 millisec. The liquid then moves across the face of the valve seat (the land) and exits in about 50 microsec. The homogenization phenomena is completed before the fluid leaves the area between the valve and the seat, and therefore emulsification is initiated and completed in less than 50 microsec. The whole process occurs between 2 pieces of steel in a steel valve assembly. The product may then pass through a second stage valve similar to the first stage. While most of the fat globule reduction takes place in the first stage, there is a tendency for clumping or clustering of the reduced fat globules. The second stage valve permits the separation of those clusters into individual fat globules.




Homogenizer and Valve 17 KB



It is most likely that a combination of two theories, turbulence and cavitation, explains the reduction in size of the fat globules during the homogenization process.

Turbulence

Energy, dissipating in the liquid going through the homogenizer valve, generates intense turbulent eddies of the same size as the average globule diameter. Globules are thus torn apart by these eddie currents reducing their average size.

Cavitation

Considerable pressure drop with charge of velocity of fluid. Liquid cavitates because its vapor pressure is attained. Cavitation generates further eddies that would produce disruption of the fat globules. The high velocity gives liquid a high kinetic energy which is disrupted in a very short period of time. Increased pressure increases velocity. Dissipation of this energy leads to a high energy density (energy per volume and time). Resulting diameter is a function of energy density.

In summary, the homogenization variables are:

• type of valve
• pressure
• single or two-stage
• fat content
• surfactant type and content
• viscosity
• temperature

Also to be considered are the droplet diameter (the smaller, the more difficult to disrupt), and the log diameter which decreases linearly with log P and levels off at high pressures.

Effect of Homogenization:

Fat globule

                         No Homogenization           15 MPa (2500 psig)   
Av. diam. (µ m)                  3.3                        0.4   
Max. diam. (µ m)               10                           2   
Surf. area (m2/ml of milk)       0.08                        0.75   
Number of globules (µ m-3)      0.02                         12

Surface layer

The milk fat globule has a native membrane, picked up at the time of secretion, made of amphiphilic molecules with both hydrophilic and hydrophobic sections. This membrane lowers the interfacial tension resulting in a more stable emulsion. During homogenization, there is a tremendous increase in surface area and the native milk fat globule membrane (MFGM) is lost. However, there are many amphiphilic molecules present from the milk plasma that readily adsorb: casein micelles (partly spread) and whey proteins. The interfacial tension of raw milk is 1-2 mN/m, immediately after homogenization it is unstable at 15 mN/m, and shortly becomes stable (3-4 mN/m) as a result of the adsorption of protein. The transport of proteins is not by diffusion but mainly by convection. Rapid coverage is achieved in less than 10 sec but is subject to some rearrangement. Surface excess is a measure of how much protein is adsorbed; for example 10 mg/m² translates to a thickness of adsorbed layer of approximately 15 nm.