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Tuesday, July 2, 2013
Thursday, February 7, 2013
SATA & PCIe
SATA
Serial ATA (SATA) was designed to replace the older AT Attachment standard (ATA; later referred to as Parallel ATA or PATA). The operation of SATA is defined by Intel's Advanced Host Controller Interface (AHCI) standard. The specification describes a system memory structure for computer hardware vendors to exchange data between host system memory and attached storage devices. It allows the use of advanced features of SATA such as hotplug and native command queuing (NCQ). AHCI is supported out of the box on Windows Vista and newer versions of Windows.
Many SATA controllers offer selectable modes of operation: legacy Parallel ATA emulation, standard AHCI mode, or vendor-specific RAID (which generally enables AHCI). Windows Vista and Windows 7, do not configure themselves to load the AHCI driver upon boot if the SATA-drive controller was not in AHCI mode at the time of installation. For this reason, Intel recommends choosing RAID mode on their motherboards (which also enables AHCI) rather than AHCI/SATA mode for maximum flexibility.
SATA uses a point-to-point architecture. The physical connection between a controller and a storage device is not shared among other controllers and storage devices. SATA defines multipliers, which allows a single SATA controller to drive multiple storage devices. The multiplier performs the function of a hub; the controller and each storage device is connected to the hub. For this reason, SCSI drives provide greater sustained throughput than multiple SATA drives connected via a simple (i.e. command-based) port multiplier because of disconnect-reconnect and aggregating performance.
SATA revision 1.0 - 1.5 Gbit/s - 150 MB/s
PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe, is a high-speed serial computer expansion bus standard designed to replace the older PCI, PCI-X, and AGP bus standards. PCI uses a shared parallel bus architecture, where the PCI host and all devices share a common set of address/data/control lines. In contrast, PCIe is an interconnect bus based on point-to-point topology, with separate serial links connecting every device to the root complex (host).
The PCIe link between two devices can consist of anywhere from 1 to 32 lanes. The PCIe standard defines slots and connectors for multiple widths: ×1, ×4, ×8, ×16, ×32. A lane is composed of two differential signaling pairs: one pair for receiving data, the other for transmitting it. Conceptually, each lane is used as a full-duplex byte stream, transporting data packets in eight-bit 'byte' format, between endpoints of a link, in both directions simultaneously.
A PCI-X (133 MHz 64-bit) device and PCIe device at 4-lanes (×4), Gen1 speed have roughly the same peak transfer rate in a single-direction: 1064 MB/sec. The PCIe bus has the potential to perform better than the PCI-X bus in cases where multiple devices are transferring data communicating simultaneously, or if communication with the PCIe peripheral is bidirectional.
PCI Express 1.0a (PCI Express 1.1, 2005)
External Uses
Serial ATA (SATA) was designed to replace the older AT Attachment standard (ATA; later referred to as Parallel ATA or PATA). The operation of SATA is defined by Intel's Advanced Host Controller Interface (AHCI) standard. The specification describes a system memory structure for computer hardware vendors to exchange data between host system memory and attached storage devices. It allows the use of advanced features of SATA such as hotplug and native command queuing (NCQ). AHCI is supported out of the box on Windows Vista and newer versions of Windows.
Many SATA controllers offer selectable modes of operation: legacy Parallel ATA emulation, standard AHCI mode, or vendor-specific RAID (which generally enables AHCI). Windows Vista and Windows 7, do not configure themselves to load the AHCI driver upon boot if the SATA-drive controller was not in AHCI mode at the time of installation. For this reason, Intel recommends choosing RAID mode on their motherboards (which also enables AHCI) rather than AHCI/SATA mode for maximum flexibility.
SATA uses a point-to-point architecture. The physical connection between a controller and a storage device is not shared among other controllers and storage devices. SATA defines multipliers, which allows a single SATA controller to drive multiple storage devices. The multiplier performs the function of a hub; the controller and each storage device is connected to the hub. For this reason, SCSI drives provide greater sustained throughput than multiple SATA drives connected via a simple (i.e. command-based) port multiplier because of disconnect-reconnect and aggregating performance.
SATA revision 1.0 - 1.5 Gbit/s - 150 MB/s
- Taking 8b/10b encoding overhead into account, they have an actual uncoded transfer rate of 1.2 Gbit/s (150 MB/s).
- Do not support Native Command Queuing (NCQ).
- Backward compatible with SATA 1.5 Gbit/s.
- Taking 8b/10b encoding into account, the maximum uncoded transfer rate is 2.4 Gbit/s (300 MB/s).
- Taking 8b/10b encoding into account, the maximum uncoded transfer rate is 4.8 Gbit/s (600 MB/s).
- Isochronous Native Command Queuing (NCQ) streaming command to enable isochronous quality of service data transfers for streaming.
- An NCQ Management feature that helps optimize performance by enabling host processing and management of outstanding NCQ commands.
- The enhancements are aimed at improving quality of service for video streaming and high-priority interrupts.
- mSATA, SATA for solid-state drives in mobile computing devices, a PCI Express Mini Card-like connector (electrically compatible).
- Data signals (TX±/RX± SATA, PETn0 PETp0 PERn0 PERp0 PCI-express) need connection to the SATA host controller instead of the PCI-express host controller.
- Queued TRIM Command, improves solid-state drive performance.
- Required Link Power Management, reduces overall system power demand of several SATA devices.
- A small low insertion force (LIF) connector for more compact 1.8-inch storage devices.
- SATA Express uses SATA software protocols over the PCIe hardware interface to increase SATA transfer speeds up to 8Gbit/s or 16Gbit/s.
- µSSD (micro SSD) introduces a ball grid array electrical interface for miniaturized, embedded SATA storage.
PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe, is a high-speed serial computer expansion bus standard designed to replace the older PCI, PCI-X, and AGP bus standards. PCI uses a shared parallel bus architecture, where the PCI host and all devices share a common set of address/data/control lines. In contrast, PCIe is an interconnect bus based on point-to-point topology, with separate serial links connecting every device to the root complex (host).
The PCIe link between two devices can consist of anywhere from 1 to 32 lanes. The PCIe standard defines slots and connectors for multiple widths: ×1, ×4, ×8, ×16, ×32. A lane is composed of two differential signaling pairs: one pair for receiving data, the other for transmitting it. Conceptually, each lane is used as a full-duplex byte stream, transporting data packets in eight-bit 'byte' format, between endpoints of a link, in both directions simultaneously.
A PCI-X (133 MHz 64-bit) device and PCIe device at 4-lanes (×4), Gen1 speed have roughly the same peak transfer rate in a single-direction: 1064 MB/sec. The PCIe bus has the potential to perform better than the PCI-X bus in cases where multiple devices are transferring data communicating simultaneously, or if communication with the PCIe peripheral is bidirectional.
PCI Express 1.0a (PCI Express 1.1, 2005)
- PCIe 1.x uses an 8b/10b encoding scheme that results in a 20 percent ((10-8)/10) overhead on the raw bit rate. It uses a 2.5 GHz clock rate, therefore delivering an effective 250 000 000 bytes per second (250 MB/s) maximum data rate.
- Doubles the transfer rate compared with PCIe 1.0 to 5 GT/s and the per-lane throughput rises from 250 MB/s to 500 MB/s. This means a 32-lane PCIe connector (×32) can support throughput up to 16 GB/s aggregate.
- PCIe 2.0 uses 8b/10b encoding scheme, in account of 20% overhead, the effective max transfer rate is 4 Gbit/s.
- Intel's first PCIe 2.0 capable chipset was the X38. AMD started supporting PCIe 2.0 with its AMD 700 chipset series and nVidia started with the MCP72.
- Bit rate of 8 gigatransfers per second (GT/s). Other new features for the PCIe 3.0 specification include a number of optimizations for enhanced signaling and data integrity, including transmitter and receiver equalization, PLL improvements, clock data recovery, and channel enhancements for currently supported topologies.
- PCIe 3.0 upgrades the encoding scheme to 128b/130b from the previous 8b/10b, reducing the overhead to approximately 1.5% ((130-128)/130). This is achieved by a technique called "scrambling" that applies a known binary polynomial to a data stream in a feedback topology. Because the scrambling polynomial is known, the data can be recovered by running it through a feedback topology using the inverse polynomial.
- AMD graphic card, the Radeon HD 7970, launched on January 9, 2012, is the world's first PCIe 3.0 graphic card. The new interface would prove advantageous when used for general purpose computing with technologies like OpenCL, CUDA and C++ AMP.
External Uses
- PCI Express protocol can be used as data interface to flash memory devices, such as memory cards and solid state drives. One such format is XQD card developed by the CompactFlash Association, SATA Express and SCSI Express.
- Many high-performance, enterprise-class solid state drives are designed as PCI Express RAID controller cards with flash memory chips placed directly on the circuit board; this allows much higher transfer rates (over 1 Gbyte/s) and IOPS (I/O operations per second) (over 1 million) comparing to Serial ATA or SAS drives.
Monday, February 4, 2013
Chateau Clos L’Eglise
Clos L’Eglise is best described as rich, full bodied and opulent, expressing ripe plums, chocolate and floral characteristics. The wine ages well and needs at least a decade after bottling to develop and mature, as well as allow the oak to integrate before drinking.
The estate of Clos L’Eglise is one of the older chateaux in Pomerol. Pomerol neighbouring appellation of Saint-Émilion. The predominant grape variety is Merlot, often with Cabernet Franc and smaller quantities of Cabernet Sauvignon. The mostly small-sized producers in this area of about 7.60 km2 produce red wines.
Back to the 18th century, the Chateau Clos L’Eglise was a large, 14 hectare property. The terroir of Clos L’Eglise is filled with rich clay and gravel based soil with iron deposits. The wine of Clos L’Eglise is aged in 100% new French oak barrels for between 16 and 18 months. The second wine is Esprit de L’Eglise.
2006 Clos l'Église
The color has lightened and secondary aromas of earth, truffle, cocoa, dark cherry and spice were beginning to make themselves known. Medium bodied, round, soft and filled with a melange of ripe cherries.
The estate of Clos L’Eglise is one of the older chateaux in Pomerol. Pomerol neighbouring appellation of Saint-Émilion. The predominant grape variety is Merlot, often with Cabernet Franc and smaller quantities of Cabernet Sauvignon. The mostly small-sized producers in this area of about 7.60 km2 produce red wines.
Back to the 18th century, the Chateau Clos L’Eglise was a large, 14 hectare property. The terroir of Clos L’Eglise is filled with rich clay and gravel based soil with iron deposits. The wine of Clos L’Eglise is aged in 100% new French oak barrels for between 16 and 18 months. The second wine is Esprit de L’Eglise.
2006 Clos l'Église
The color has lightened and secondary aromas of earth, truffle, cocoa, dark cherry and spice were beginning to make themselves known. Medium bodied, round, soft and filled with a melange of ripe cherries.
Monday, January 28, 2013
Gluten and Flour
Gluten
The seeds of most flowering plants have endosperms with stored protein to nourish embryonic plants during germination. Gluten 麵筋 (from Latin gluten, "glue") is a protein composite found in foods processed from wheat and related grain species. The prolamin and glutelin from wheat constitute about 80% of the protein contained in wheat seed. Gluten content has been implicated as a factor in the staling of bread, possibly because it binds water through hydration.
Gluten forms when glutenin ( only soluble in dilute acids or alkalis) molecules cross-link to form a sub-microscopic network attached to gliadin (alcohol-soluble). It gives elasticity to dough, helping it rise and keep its shape and often gives the final product a chewy texture. True gluten, with gliadin and glutenin, is limited to certain members of the grass family. The stored proteins of maize and rice are sometimes called glutens, but their proteins differ from true gluten.
Flour
Flour is a powder which is made by grinding cereal grains, other seeds or roots. Flour contains a high proportion of starches, which are a subset of complex carbohydrates also known as polysaccharides. Baking coagulates the gluten, which, along with starch, stabilizes the shape of the final product. The higher the protein content the harder and stronger the flour, and the more it will produce crusty or chewy breads. The lower the protein the softer the flour, which is better for cakes, cookies, and pie crusts.
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight.
Starch molecules arrange themselves in the plant in semi-crystalline granules. Each plant species has a unique starch granular size: rice starch is relatively small (about 2μm) while potato starches have larger granules (up to 100μm). Pure starch is a white, tasteless and odourless powder that is insoluble in cold water or alcohol. "Oobleck" or "ooze", suspension of starch (e.g. cornstarch) in water, is a non-Newtonian fluid. In a Newtonian fluid, the relation between the shear stress and the shear rate is linear, passing through the origin, the constant of proportionality being the coefficient of viscosity. In a non-Newtonian fluid, the relation between the shear stress and the shear rate is different, and can even be time-dependent. Therefore, a constant coefficient of viscosity cannot be defined.
Starch becomes soluble in water when heated. The granules swell and burst, the semi-crystalline structure is lost and the smaller amylose molecules start leaching out of the granule, forming a network that holds water and increasing the mixture's viscosity. This process is called starch gelatinization. During cooking, the starch becomes a paste and increases further in viscosity. During cooling or prolonged storage of the paste, the semi-crystalline structure partially recovers and the starch paste thickens, expelling water. This is mainly caused by retrogradation of the amylose.
Rice flour (粘米粉) is ground kernels of rice. It does not contain gluten. It is distinct from rice starch, which is usually produced by steeping rice in lye.
Wheat flour varieties are called "clean," "white," or "brown" ("strong", "hard") if they have high gluten content, and they are called "soft" or "weak" flour if gluten content is low.
The seeds of most flowering plants have endosperms with stored protein to nourish embryonic plants during germination. Gluten 麵筋 (from Latin gluten, "glue") is a protein composite found in foods processed from wheat and related grain species. The prolamin and glutelin from wheat constitute about 80% of the protein contained in wheat seed. Gluten content has been implicated as a factor in the staling of bread, possibly because it binds water through hydration.
Gluten forms when glutenin ( only soluble in dilute acids or alkalis) molecules cross-link to form a sub-microscopic network attached to gliadin (alcohol-soluble). It gives elasticity to dough, helping it rise and keep its shape and often gives the final product a chewy texture. True gluten, with gliadin and glutenin, is limited to certain members of the grass family. The stored proteins of maize and rice are sometimes called glutens, but their proteins differ from true gluten.
Flour
Flour is a powder which is made by grinding cereal grains, other seeds or roots. Flour contains a high proportion of starches, which are a subset of complex carbohydrates also known as polysaccharides. Baking coagulates the gluten, which, along with starch, stabilizes the shape of the final product. The higher the protein content the harder and stronger the flour, and the more it will produce crusty or chewy breads. The lower the protein the softer the flour, which is better for cakes, cookies, and pie crusts.
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight.
Starch molecules arrange themselves in the plant in semi-crystalline granules. Each plant species has a unique starch granular size: rice starch is relatively small (about 2μm) while potato starches have larger granules (up to 100μm). Pure starch is a white, tasteless and odourless powder that is insoluble in cold water or alcohol. "Oobleck" or "ooze", suspension of starch (e.g. cornstarch) in water, is a non-Newtonian fluid. In a Newtonian fluid, the relation between the shear stress and the shear rate is linear, passing through the origin, the constant of proportionality being the coefficient of viscosity. In a non-Newtonian fluid, the relation between the shear stress and the shear rate is different, and can even be time-dependent. Therefore, a constant coefficient of viscosity cannot be defined.
Starch becomes soluble in water when heated. The granules swell and burst, the semi-crystalline structure is lost and the smaller amylose molecules start leaching out of the granule, forming a network that holds water and increasing the mixture's viscosity. This process is called starch gelatinization. During cooking, the starch becomes a paste and increases further in viscosity. During cooling or prolonged storage of the paste, the semi-crystalline structure partially recovers and the starch paste thickens, expelling water. This is mainly caused by retrogradation of the amylose.
- Plain or all-purpose flour does not have a leavening agent.
- Self-rising (or self-raising) flour is sold premixed with chemical leavening agents. The added ingredients are evenly distributed throughout the flour which aids a consistent rise in baked goods. This flour is generally used for preparing scones, biscuits, muffins, etc.
Corn (maize) flour should never be confused with cornstarch, which is known as "cornflour" in British English. Coarse whole-grain corn flour is usually called corn meal.
Corn starch, cornstarch, cornflour or maize starch is the starch of the corn (maize) grain obtained from the endosperm of the corn kernel. It is used as a thickening agent in soups and liquid-based foods. Corn starch is sometimes preferred over flour because it forms a translucent mixture, rather than an opaque one.
Tapioca Starch/ Tapioca Flour/ Potato Starch (木薯粉/泰國生粉/太白粉) is obtained by grinding the tubers of potato to a pulp and removing the fibre and protein by water-washings. It is very white starch powder used as a thickening agent. Standard potato starch needs boiling, to thicken in water, giving a transparent gel. 食物放涼之後，茨汁會變得較稀，因此一般整蛋糕/做西點多利用粟粉來達到粘稠的特性而不使用太白粉。
Corn starch, cornstarch, cornflour or maize starch is the starch of the corn (maize) grain obtained from the endosperm of the corn kernel. It is used as a thickening agent in soups and liquid-based foods. Corn starch is sometimes preferred over flour because it forms a translucent mixture, rather than an opaque one.
Tapioca Starch/ Tapioca Flour/ Potato Starch (木薯粉/泰國生粉/太白粉) is obtained by grinding the tubers of potato to a pulp and removing the fibre and protein by water-washings. It is very white starch powder used as a thickening agent. Standard potato starch needs boiling, to thicken in water, giving a transparent gel. 食物放涼之後，茨汁會變得較稀，因此一般整蛋糕/做西點多利用粟粉來達到粘稠的特性而不使用太白粉。
Glutinous rice flour (糯米粉) or sticky rice flour, used in east and southeast Asian cuisines for making tangyuan, etc.
Rice flour (粘米粉) is ground kernels of rice. It does not contain gluten. It is distinct from rice starch, which is usually produced by steeping rice in lye.
Wheat flour varieties are called "clean," "white," or "brown" ("strong", "hard") if they have high gluten content, and they are called "soft" or "weak" flour if gluten content is low.
- Cake flour (低筋麵粉) is a finely milled white flour made from soft wheat. It has very low protein content, between 8% - 10%, making it suitable for soft-textured cakes and cookies. 適合用來做糕點、雪芳蛋糕、笑口棗、鍋餅等
- Pastry flour or cookie flour or cracker flour has slightly higher protein content than cake flour but lower than all-purpose flour. Its protein content ranges between 9% - 10%. It is suitable for pie pastry and tarts, some cookies, muffins, biscuits and other quick breads.
- All-purpose or plain flour (中筋麵粉) is a blended wheat flour with a protein content lower than bread flour, ranging 9% - 12%. The increased protein binds to the flour to entrap carbon dioxide released by the yeast fermentation process, resulting in a stronger rise. 大部分中式點心都是以中筋粉來製作的。
- Bread flour or strong flour (高筋麵粉) is always made from hard wheat, usually hard spring wheat. It has a very high protein content, between 10% - 13%, making it excellent for yeast bread baking. 適合用來做麵包、派皮、鬆餅、餃子皮、麵條等
- Tang flour or wheat starch (澄麵/無筋面粉)) is a type of wheat flour used primarily in Chinese cooking for making the outer layer of dumplings and buns. 澄麵是從小麥萃取澱粉所製成，是一種完全不含蛋白質的麵粉，因此缺乏黏合力，需加入熱水讓部份澄麵中的澱粉糊化，才可和其他澄麵結合起來。澄麵糰成型之後，若用刀將皮拉薄，就是廣式點心常見的澄麵皮，可用來做蝦餃、水晶皮等，蒸熟後餡枓若隱若現，看起來晶瑩剔透。
Monday, January 21, 2013
"The Large" Breaking the Cosmological Principle
Large Quasar Group (LQG)
An international team of astronomers, Using data from the Sloan Digital Sky Survey, has found the largest known structure in the universe - large quasar group (LQG). This LQG is so large that it would take a vehicle travelling at the speed of light some 4 billion years to cross it. For comparison, our own galaxy, the Milky Way, is just a hundred thousand light-years across, while the local supercluster of galaxies in which it's located, the Virgo Cluster, is only a hundred million light-years wide.
Cosmological Principle
The usual models of the Universe in cosmology are built on the assumption of the cosmological principle – assumption of homogeneity after imagined smoothing on some suitably large scale. Models depend on the Robertson–Walker metric assumes the homogeneity of the mass–energy density. Further, assumes that any property of the Universe ultimately depends on the mass–energy content then homogeneity naturally asserts that any global property of sufficiently large volumes should be the same within the expected statistical variations.
The Milky Way, our galaxy, is separated from its nearest neighbour, the Andromeda Galaxy, by about 0.75 Megaparsecs (Mpc) or 2.5 million light-years. Whole clusters of galaxies can be 2-3 Mpc across but LQGs can be 200 Mpc or more across. Based on the Cosmological Principle and the modern theory of cosmology, calculations suggest that astrophysicists should not be able to find a structure larger than 370 Mpc.
The new discovered LQG has a typical dimension of 500 Mpc, membership of 73 quasars and mean redshift z¯=1.27. In terms of both size and membership, it is the most extreme LQG found in the DR7QSO catalogue for the redshift range 1.0 ≤ z ≤ 1.8. But because it is elongated, its longest dimension is 1240 Mpc (or 4 billion light years) - some 1600 times larger than the distance from the Milky Way to Andromeda.
Implications
An international team of astronomers, Using data from the Sloan Digital Sky Survey, has found the largest known structure in the universe - large quasar group (LQG). This LQG is so large that it would take a vehicle travelling at the speed of light some 4 billion years to cross it. For comparison, our own galaxy, the Milky Way, is just a hundred thousand light-years across, while the local supercluster of galaxies in which it's located, the Virgo Cluster, is only a hundred million light-years wide.
Cosmological Principle
The usual models of the Universe in cosmology are built on the assumption of the cosmological principle – assumption of homogeneity after imagined smoothing on some suitably large scale. Models depend on the Robertson–Walker metric assumes the homogeneity of the mass–energy density. Further, assumes that any property of the Universe ultimately depends on the mass–energy content then homogeneity naturally asserts that any global property of sufficiently large volumes should be the same within the expected statistical variations.
The Milky Way, our galaxy, is separated from its nearest neighbour, the Andromeda Galaxy, by about 0.75 Megaparsecs (Mpc) or 2.5 million light-years. Whole clusters of galaxies can be 2-3 Mpc across but LQGs can be 200 Mpc or more across. Based on the Cosmological Principle and the modern theory of cosmology, calculations suggest that astrophysicists should not be able to find a structure larger than 370 Mpc.
The new discovered LQG has a typical dimension of 500 Mpc, membership of 73 quasars and mean redshift z¯=1.27. In terms of both size and membership, it is the most extreme LQG found in the DR7QSO catalogue for the redshift range 1.0 ≤ z ≤ 1.8. But because it is elongated, its longest dimension is 1240 Mpc (or 4 billion light years) - some 1600 times larger than the distance from the Milky Way to Andromeda.
Implications
- The occurrence of structure on Gpc-scales from the Huge-LQG and from galaxies implies that the Universe is not homogeneous on these scales.
- The Huge-LQG would also indicate that there is more dark matter in some directions than in others. Such mass concentrations could conceivably be associated with the cosmic (dark) flows on the scales of ∼100–1000 Mpc. Of particular interest is the possibility raised by Tsagas (2012) that those living within a large-scale cosmic flow could see local acceleration of the expansion within a Universe that is decelerating overall.
Friday, January 18, 2013
Soft Chocolate & Chocolate Ice Cream
What we know about milk, cream and chocolate
Next:
For soft chocolate, the optimal composition is about 10% water and 30% fat.
For ice cream, the optimal composition is about 55% water and >32% fat.
Milk is an emulsion of butterfat globules within a water-based fluid.
Whipping cream contains 30-36% butterfat.
Butter contains at least 80% butterfat.
Milk chocolate contains cocoa solids, cocoa butter (or other fat), sugar, and milk powder (or condensed milk).
Butterfat is a triglyceride derived from myristic, palmitic, and oleic acids.
Cocoa butter is a triglyceride (fat) derived from stearic, palmitic, and oleic acids.
Whipping cream is an emulsion of butterfat in water.
Butter is an emulsion of water in butterfat.
In cocoa butter, there are six essential polymorphic forms.
Examples of food emulsifiers are egg yolk (lecithin), mustard, protein, and soy lecithin.
Average milk freezing point is –0.523°C.
Melting temperature of butter is 28-36 °C (butter is partially solidify at room temperature).
Melting temperature of chocolate: Type V 34 °C, Type VI 36 °C (body temperature 37 °C).
What is an Ice Cream
Ice cream is a smoothly textured semi-solid (frozen) foam that made from milk/cream, and often combined with fruits and flavours. In USA, it may have the following composition:
- at least 10% butterfat.
- 9 - 12% milk solids (not fat) contains: proteins (caseins and whey proteins) and carbohydrates (lactose) found in milk.
- 12 - 16 % glucose-based corn syrup sweeteners
- 0.2 - 0.5% stabilisers and emulsifiers
- 55% - 64% water (from the milk or other ingredients).
The mixture of these ingredients is stirred slowly while cooling, in order to incorporate air and to prevent large ice crystals from forming.
Gelato, Italian word for ice cream, derived from the Latin word "gelātus." (meaning frozen). In English, gelato is defined as a soft ice cream containing little or no air. By statute, gelato in Italy must have at least 3.5% butterfat, with no upper limit established.
In order to keep ice cream soft, we have to avoid ice crystals forming. There are tricks to do so:
In order to keep ice cream soft, we have to avoid ice crystals forming. There are tricks to do so:
- Emulsifying fat - sticks fat molecules in between water molecules.
- Sugar - the higher the concentration of sugar (syrup), the lower the freezing point.
- Air - a more aerated ice cream is easier to scoop, and has a fluffier, less dense texture.
- Others - alcohol, starch, protein (in egg and milk), and natural stabilizers like guar gum.
Melting the Chocolate
When melting chocolate, be careful not to allow excess steam to develop, which will interface with the surface of the chocolate, moistening it and increasing the viscosity. The addition of 3% or 4% by weight of water will turn chocolate into a very thick paste. Continuous to increase the amount of water, say above 20%, there is enough water to form continuous streams through the chocolate and so help it flow.
Milk fat has the same effect as cocoa butter on viscosity. Milk fat will slow down the setting rate of chocolate if it is added at temperature 40°C. The effect of an extra 1% of fat upon the viscosity depends upon the amount that is already present. Above a fat contents of 32% there is very little change in viscosity with any further additions. The effect of fat is proportionately much higher for the plastic viscosity then the yield value. The majority of the fat is wetting fat, which is partially tied to the particles surface. This free fat has a large effect on lubricating the flow when it takes place and so the plastic viscosity decreases dramatically. On the other hand, the yield value is more connected with the forces between the solid particles, which in turn are connected with the absolute distance between them.
Cream can be added to chocolate to form a soft mixture, known as ganache, that does not have any snap when broken and does not contract very much upon cooling. This is made by stirring the cream very rigorously as liquid chocolate is added to it. Because there are emulsifiers in both cream and chocolate, the chocolate viscosity is slightly less affected by the moisture.
Chocolate is almost half made up of very tiny sugar particles. Sugar particles are hydrophilic (attract water) but lipophilic (repel fat). Liquid chocolate flow because the sugar and the other solid particles are able to move past one another. In this case, the emulsifier coats the solid surface and forms a boundary layer between the two and is more a surface active agent than a emulsifier. The most common surface active agent used is lecithin which is a naturally occurring substance frequently obtained from soya. Addition of 0.1 - 0.3% soya lecithin are said to reduce the viscosity by more than 10 times their own weight of cocoa butter.
(Ref: The Science of Chocolate, P.77
http://books.google.com.hk/books?id=miv82VGPL9cC&pg=PA77&lpg=PA77&dq=chocolate+attract+water&source=bl&ots=J2Ie_Al2eE&sig=mqmws11NP982uQ3xW5xjykuIDFk&hl=en&sa=X&ei=ENn4UM3fDKnAiQfH_oCQAg&redir_esc=y#v=onepage&q=chocolate%20attract%20water&f=false)
Experiments
Values used:
Milk chocolate weigh to volume conversion: 100g = 140.83 ml
Milk chocolate: cocoa solid 26%, milk solid 28%, total fat 29.6%
Cream: butterfat 35%
When melting chocolate, be careful not to allow excess steam to develop, which will interface with the surface of the chocolate, moistening it and increasing the viscosity. The addition of 3% or 4% by weight of water will turn chocolate into a very thick paste. Continuous to increase the amount of water, say above 20%, there is enough water to form continuous streams through the chocolate and so help it flow.
Milk fat has the same effect as cocoa butter on viscosity. Milk fat will slow down the setting rate of chocolate if it is added at temperature 40°C. The effect of an extra 1% of fat upon the viscosity depends upon the amount that is already present. Above a fat contents of 32% there is very little change in viscosity with any further additions. The effect of fat is proportionately much higher for the plastic viscosity then the yield value. The majority of the fat is wetting fat, which is partially tied to the particles surface. This free fat has a large effect on lubricating the flow when it takes place and so the plastic viscosity decreases dramatically. On the other hand, the yield value is more connected with the forces between the solid particles, which in turn are connected with the absolute distance between them.
Chocolate is almost half made up of very tiny sugar particles. Sugar particles are hydrophilic (attract water) but lipophilic (repel fat). Liquid chocolate flow because the sugar and the other solid particles are able to move past one another. In this case, the emulsifier coats the solid surface and forms a boundary layer between the two and is more a surface active agent than a emulsifier. The most common surface active agent used is lecithin which is a naturally occurring substance frequently obtained from soya. Addition of 0.1 - 0.3% soya lecithin are said to reduce the viscosity by more than 10 times their own weight of cocoa butter.
(Ref: The Science of Chocolate, P.77
http://books.google.com.hk/books?id=miv82VGPL9cC&pg=PA77&lpg=PA77&dq=chocolate+attract+water&source=bl&ots=J2Ie_Al2eE&sig=mqmws11NP982uQ3xW5xjykuIDFk&hl=en&sa=X&ei=ENn4UM3fDKnAiQfH_oCQAg&redir_esc=y#v=onepage&q=chocolate%20attract%20water&f=false)
Experiments
Values used:
Milk chocolate weigh to volume conversion: 100g = 140.83 ml
Milk chocolate: cocoa solid 26%, milk solid 28%, total fat 29.6%
Cream: butterfat 35%
| Cream, ml | Chocolate, g | Butter, g | Refrigerator | Form | Water | Cocoa Solid | Total Fat |
| 10 | 16 | 10-14 °C | thick paste | 19.43% | 18.23% | 31.21% | |
| 20 | 21 | 10-14 °C | thick paste | 26.35% | 15.46% | 31.79% | |
| 40 | 21 | 5 | < 10 °C | icecream (soft) | 37.50% | 11.00% | 32.72% |
| 50 | 21 | freezer | icecream (hard) | 40.96% | 9.61% | 33.00% | |
| 60 | 21 | 5 | freezer | icecream (hard) | 43.65% | 8.54% | 33.23% |
| Planned Next | |||||||
| 30 | 100 | 10-14 °C | soft chocolate | 11.41% | 21.43% | 30.55% | |
| 400 | 50 | freezer | icecream (hard) | 55.27% | 3.89% | 34.19% |
Next:
For soft chocolate, the optimal composition is about 10% water and 30% fat.
For ice cream, the optimal composition is about 55% water and >32% fat.
Tuesday, January 15, 2013
Chocolate
Cocoa or dark chocolate may positively affect the circulatory system. Other possible effects under basic research include anticancer, brain stimulator, cough preventor and antidiarrhoeal activities.
Chocolate is a raw or processed food produced from the seed of the tropical Theobroma cacao tree. After fermentation, the beans are dried, then cleaned, and then roasted, and the shell is removed to produce cacao nibs. The nibs are then ground to cocoa mass, pure chocolate in rough form. The mass is melted to become the liquor. Chocolate liquor contains roughly 53 percent cocoa butter (fat), about 17 percent carbohydrates, 11 percent protein, 6 percent tannins, and 1.5 percent theobromine. Chocolate liquor is pressed to separate the cocoa butter from the cocoa solids. White chocolate contains cocoa butter, sugar, and milk but no cocoa solids.
Cocoa Butter
Cocoa butter, also called theobroma oil, is a pale-yellow, pure, edible vegetable fat extracted from the cocoa bean, has a cocoa flavor and aroma. Cocoa butter contains a high proportion of saturated fats, derived from stearic and palmitic acids. Unlike cocoa solids, it has no more than trace amounts of caffeine and theobromine. It is one of the most stable fats known, a quality that coupled with natural antioxidants that prevent rancidity, grants it a storage life of two to five years. The velvety texture, pleasant fragrance and emollient properties of cocoa butter have made it a popular ingredient in products for the skin, such as cosmetics, soaps and lotions.
Cocoa Solids
Cocoa solids contain alkaloids such as theobromine(可可碱) and phenethylamine(PEA,苯乙胺), which have physiological effects on the body. It has been linked to serotonin levels in the brain. In medicine, theobromine is used as a vasodilator (a blood vessel widener), a diuretic (urination aid), and heart stimulant. The presence of theobromine renders chocolate toxic to some animals, especially dogs and cats. Phenylethylamine functions as a neuromodulator or neurotransmitter in the mammalian central nervous system. Orally ingested phenethylamine is usually inactive because of extensive first-pass metabolism by monoamine oxidase (MAO) into phenylacetic acid. This prevents significant concentrations from reaching the brain.
Serotonin and tryptophan(色氨酸) have been found in chocolate with varying cocoa contents. The highest serotonin content (2.93 ug g-1) was found in chocolate with 85% cocoa, and the highest tryptophan content (13.27-13.34 ug g-1) was found in 70-85% cocoa.
Serotonin (血清素) or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal (GI) tract, platelets, and in the central nervous system (CNS) of animals including humans. Approximately 90% of the human body's total serotonin is located in the enterochromaffin cells in the alimentary canal (gut), where it is used to regulate intestinal movements. The remainder is synthesized in serotonergic neurons of the CNS, where it has various functions. These include the regulation of mood, appetite, and sleep. Serotonin also has some cognitive functions, including memory and learning.
Serotonin taken orally does not pass into the serotonergic pathways of the central nervous system, because it does not cross the blood–brain barrier. However, tryptophan and its metabolite 5-hydroxytryptophan (5-HTP), from which serotonin is synthesized, can and do cross the blood–brain barrier. Several classes of drugs target the 5-HT system, including some antidepressants, antipsychotics, anxiolytics, antiemetics, and antimigraine drugs, as well as the psychedelic drugs and empathogens.
Because serotonin is a major gastrointestinal tract modulator, it may be produced by plants in fruits as a way of speeding the passage of seeds through the digestive tract, in the same way as many well-known seed and fruit associated laxatives. Serotonin is found in mushrooms, fruits and vegetables. The highest values of 25–400 mg/kg have been found in nuts of the walnut (Juglans) and hickory (Carya) genera. Serotonin concentrations of 3–30 mg/kg have been found in plantains, pineapples, banana, kiwifruit, plums, and tomatoes.
Tempering
Chocolate is a raw or processed food produced from the seed of the tropical Theobroma cacao tree. After fermentation, the beans are dried, then cleaned, and then roasted, and the shell is removed to produce cacao nibs. The nibs are then ground to cocoa mass, pure chocolate in rough form. The mass is melted to become the liquor. Chocolate liquor contains roughly 53 percent cocoa butter (fat), about 17 percent carbohydrates, 11 percent protein, 6 percent tannins, and 1.5 percent theobromine. Chocolate liquor is pressed to separate the cocoa butter from the cocoa solids. White chocolate contains cocoa butter, sugar, and milk but no cocoa solids.
Cocoa Butter
Cocoa butter, also called theobroma oil, is a pale-yellow, pure, edible vegetable fat extracted from the cocoa bean, has a cocoa flavor and aroma. Cocoa butter contains a high proportion of saturated fats, derived from stearic and palmitic acids. Unlike cocoa solids, it has no more than trace amounts of caffeine and theobromine. It is one of the most stable fats known, a quality that coupled with natural antioxidants that prevent rancidity, grants it a storage life of two to five years. The velvety texture, pleasant fragrance and emollient properties of cocoa butter have made it a popular ingredient in products for the skin, such as cosmetics, soaps and lotions.
Cocoa solids contain alkaloids such as theobromine(可可碱) and phenethylamine(PEA,苯乙胺), which have physiological effects on the body. It has been linked to serotonin levels in the brain. In medicine, theobromine is used as a vasodilator (a blood vessel widener), a diuretic (urination aid), and heart stimulant. The presence of theobromine renders chocolate toxic to some animals, especially dogs and cats. Phenylethylamine functions as a neuromodulator or neurotransmitter in the mammalian central nervous system. Orally ingested phenethylamine is usually inactive because of extensive first-pass metabolism by monoamine oxidase (MAO) into phenylacetic acid. This prevents significant concentrations from reaching the brain.
Serotonin and tryptophan(色氨酸) have been found in chocolate with varying cocoa contents. The highest serotonin content (2.93 ug g-1) was found in chocolate with 85% cocoa, and the highest tryptophan content (13.27-13.34 ug g-1) was found in 70-85% cocoa.
Serotonin (血清素) or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal (GI) tract, platelets, and in the central nervous system (CNS) of animals including humans. Approximately 90% of the human body's total serotonin is located in the enterochromaffin cells in the alimentary canal (gut), where it is used to regulate intestinal movements. The remainder is synthesized in serotonergic neurons of the CNS, where it has various functions. These include the regulation of mood, appetite, and sleep. Serotonin also has some cognitive functions, including memory and learning.
Serotonin taken orally does not pass into the serotonergic pathways of the central nervous system, because it does not cross the blood–brain barrier. However, tryptophan and its metabolite 5-hydroxytryptophan (5-HTP), from which serotonin is synthesized, can and do cross the blood–brain barrier. Several classes of drugs target the 5-HT system, including some antidepressants, antipsychotics, anxiolytics, antiemetics, and antimigraine drugs, as well as the psychedelic drugs and empathogens.
Because serotonin is a major gastrointestinal tract modulator, it may be produced by plants in fruits as a way of speeding the passage of seeds through the digestive tract, in the same way as many well-known seed and fruit associated laxatives. Serotonin is found in mushrooms, fruits and vegetables. The highest values of 25–400 mg/kg have been found in nuts of the walnut (Juglans) and hickory (Carya) genera. Serotonin concentrations of 3–30 mg/kg have been found in plantains, pineapples, banana, kiwifruit, plums, and tomatoes.
Tempering
In cocoa butter, there are six essential polymorphic forms. Uncontrolled crystallization of cocoa butter typically results in crystals of varying size. The uniform sheen and crisp bite of properly processed chocolate are the result of consistently small cocoa butter crystals produced by the tempering process. Type V crystals is the best for serving and storing.
Crystal Melting temp.
I 17 °C (63 °F) Soft, crumbly, melts too easily
II 21 °C (70 °F) Soft, crumbly, melts too easily
III 26 °C (79 °F) Firm, poor snap, melts too easily
IV 28 °C (82 °F) Firm, good snap, melts too easily
V 34 °C (93 °F) Glossy, firm, best snap, melts near body temperature (37 °C)
VI 36 °C (97 °F) Hard, takes weeks to form
First, the chocolate is first heated to 45 °C (113 °F) to melt all six forms of crystals. Next, the chocolate is cooled to about 27 °C (81 °F), which will allow crystal types IV and V to form. At this temperature, the chocolate is agitated to create many small crystal "seeds" which will serve as nuclei to create small crystals in the chocolate. The chocolate is then heated to about 31 °C (88 °F) to eliminate any type IV crystals, leaving just type V. After this point, any excessive heating of the chocolate will destroy the temper and this process will have to be repeated.
Type V and VI are the most stable and are triple chain packing, whereas the other forms are all double.
Type V and VI are the most stable and are triple chain packing, whereas the other forms are all double.
According to polymorphic transformation theory, bloom occurs through the uncontrolled polymorphic transformation of cocoa butter from a less stable form (form IV or V) to the most stable form (form VI). In well-tempered chocolate, the production of form VI from form V does not always lead to bloom. The onset of transformation from form V to form VI crystals should be considered as an aspect of cocoa butter recrystallization that may result in bloom.
Handling Chocolate
(http://www.chocolat.bz/All%20about%20chocolate/Use%20and%20handling%20of%20chocolate/Use%20and%20handling%20of%20chocolate%20page%201.htm)
A very small amount of moisture in chocolate will noticeably increase its viscosity, making it unacceptable for dipping or enrobing. When melting chocolate, be careful not to allow excess steam to develop, which will interface with the surface of the chocolate, moistening it and increasing the viscosity.
Because chocolate contains virtually no moisture, it has very low water activity level, and is not prone to bacterial spoilage during storage, resulting in a long shelf life. The factor limiting shelf life for chocolate is rancidity, the breakdown of fats than can create off flavors. Although cocoa butter is relatively resistant to rancidity, chocolate should be stored protected from exposure to oxygen, light, heat, and moisture (humidity), and when working with chocolate, do not expose it to reactive metals such as copper and iron.
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