Carbohydrates

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Date of experiment: 19th February, 2013
Title: Carbohydrates
Object: The purpose of this practical is to determinate the solubility of carbohydrates (Galactose, Glucose and Lactose), find out the sweetness taste threshold and salt taste threshold. Also measure the sugar concentration of 3 common packaged drinks and my taste threshold sample for the 3 sugars and make the fudge. Introduction:

Carbohydrate divided into two types which is available carbohydrate and unavailable carbohydrate. Available carbohydrates include monosaccharides, disaccharides, oligosaccharides and polysaccharides. Glucose and galactose are monosaccharides and hexoses, glucose can found in grapes and blood. Lactose, sucrose and maltose are disaccharides, lactose structure is Glucose 1-2 galactose, the linkage is β1-4 glycosidic bond, it is milk sugar and is important to baby. Sucrose structure is Glucose 1-2fructose Maltose, the linkage is α1-2 glycosidic bond, it can found in plant sauces and table sugar. Maltose structure is Glucose 1-4 glucose, the linkage is α1-4 glycosidic bond, it is the most important sugar to human because human’s brain only can use energy from glucose and one maltose molecule contains two glucoses. In part 3 of the practical, was used a digital refractometer to measure sugar concentration, the working principle of the digital refractometer is that light from an LED light source is focused on the bottom surface or a prism element. When a liquid sample is added to the measuring surface of the prism, some of the light is transmitted through the solution and lost and the rest of the light is reflected to the photodiode linear array to create a shadow line. The refractive index is directly related to the position of the shadow line on the photodiodes. If position of the shadow line has been automatically determined by the instrument, the internal software will associated with the position to refractive index, or to another unit of measure related to refractive index, and display a digital readout on an LCD or LED scale.

Result:
Experiment 1
The solubility of carbohydrates (1st time)
| Glucose| Galactose| Lactose|
The weight of beaker(g)| 36.23| 36.24| 42.73|
The weight of water(g)| 10.22| 10.54| 10.02|
The weight of beaker + water + dissolved sugar(g)| 48.77| 47.38| 53.27| The weight of dissolved sugar(g)| 2.32| 0.60| 0.52|
The saturation point of the sugar(mg/ml)| 227.01| 56.93| 51.90|

The solubility of carbohydrates (2nd time)
| Glucose| Galactose| Lactose|
The weight of beaker(g)| 42.76| 42.75| 42.75|
The weight of water(g)| 9.85| 10.04| 9.18|
The weight of beaker + water + dissolved sugar(g)| 54.70| 53.42| 52.41| The weight of dissolved sugar(g)| 2.09| 0.63| 0.48|
The saturation point of the sugar(mg/ml)| 212.18| 62.75| 52.29|

The average percentage of dissolved sugar
| Glucose| Galactose| Lactose|
The average saturation point of the sugar(mg/ml)| 219.60| 59.84| 52.10|

Experiment 2
The result of sweetness taste threshold
Group mates| Glucose solution| Sucrose solution| Maltose solution| Ho (me)| 5| 3| 2|
Lam| 5| 3| 3|
Au| 5| 2| 2|
Chan| 4| 3| 2|
Chow| 1| 3| 2|

Experiment 3
The sugar concentration of 3 common packaged drinks
| American Ginseng With Honey Drink| Xia Ku Cao| Imperatae Cane Drink| The sugar concentration labeled at nutrition information (g/100mL)| 6.5| 4.8| 6.0| Sugar concentration (%BRIX)| 4.1| 3.4| 4.2|

The sugar concentration of my taste threshold sample for the 3 sugars | Glucose solution| Sucrose solution| Maltose|
Sugar concentration (%BRIX)| 2.0| 0.9| 0.5|

Experiment 4
The result of salt taste threshold
Group mates| Salt solution|
Ho (me)| 2|
Lam| 2|
Au| 2|
Chan| 2|
Chow| 2|

Discussion:
From the result of part 1, can show that the average saturation point of the glucose (219.60mg/ml) is the highest, is higher...
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