proiect miere

8/7/2019 proiect miere

1/17

Authors :Stud. Talida Mange

Stud. Daniela Manolache

Stud. Tunde Marton

Stud. Madalina Nitu

Universitatea Transilvania din Brasov

Facultatea de Alimentatie si Turism

Specializarea: Controlul si expertiza produselor alimentare

Coordinator

Fiz.drd. Andreea-Manuela CONSTANTIN


2/17

Reason of this article is that to study variation

of viscosity of honey in report with

temperature. We present the theoretic aspectsof rheology , of viscosity, the honey composition

and the dispositive used for this experiment

(electronic viscometer with vibrations SV).

Why we chose rheology?!?


3/17

Rheology is the study of the flow of matter: mainly liquids but also soft solids orsolids under conditions in which they flow rather than deform elastically. It

applies to substances which have a complex structure, including muds, sludges,

suspensions, polymers, many foods, bodily fluids and other biological materials.

The word rheology comes from rheo, from the Greek word for flow, and ology,

meaning study of. The term rheology was coined by Eugene C. Bingham, aprofessor at Lafayette College, in 1920, from a suggestion by a colleague,

Markus Reiner. The term was inspired by the quotation mistakenly attributed to

Heraclitus (actually coming from the writings of Simplicius) panta rei,

"everything flows.

Exists tree fundamental rheological properties:

- the elasticity

- the viscosity

- the plasticity


4/17

Viscosity is a fluid rheological property essential to resist

the relative movement of adjacent fluid layers, resistance

which is due to internal friction between fluid layers. At

the movement of liquid layers, one from the other, there

is an internal friction specific to each liquid that is

represented by the physical size viscosity.


5/17

Honey bee is a product obtained by processing nectar by bees.Honey is a sweet-

tasting food and easy perfumed looking semifluid, viscous or crystallized with a

specific color that has a high content of sugars, vitamins, minerals, enzymes and

organic acids.

Chemical composition of honey is influenced by many factors including: quality

and composition of raw materials (nectar), climatic factors, mode of operation of

bees, how to harvest, conditioning and its conservation. major constituents of

honey are water and sugary substances, which represent 99% from honey. The

honey is composed from fructose, sucrose and water.

Microbiological conditions for honey are:- Total number of germs must be 100/gram maximum temperature of 30C

- Colli eschirichia must be absent

- Staphylococcus coagulase positive must be maximum 10/gram

- Sarmanella must be absent on 125 grams.


6/17

For fluent alimentary products there are many types of

machines that can determine viscosity :

- thecapillary viscosity-meter

-theOstwald viscosity-meter-theEnglerviscosity-meter

-theHopplerball viscosity-meter

-theVolarovicirotary viscosity-meter

-theStromerviscosity-meter

-theBrookfield viscosity-meter

-theRheotestrotary viscosity-meter.


7/17

The viscosity-meter is compound from an U-

shape tube whose wider AB branch finishes

in the lower side with a spherical R tank. The

other branch consists in a capillary C tube, a

smaller E spherical tank and a rubber Ftube. At the entry and the exit from the E

tank there are marked two marks which

confine a well defined volume. The viscosity-

meter must stay in an upright position. In

order to perform an experiment with the

Ostwald viscosity-meter there are necessary

a suction pump and a stopwatch too.


8/17

Electronic viscometer with

vibrations SV is used for

viscosity determination certain

materials. It is produce by KSVInstruments Ltd, in Filanda. The

dispositive represent a subset

compose from two sensors with

thin strips. Electronic

viscometer with vibrations SV isequipped with WinCT-Viscosity

program, Windows

Communication Tools Software ,

with which are obtained graphics

in real time of viscosity andtem erature.


9/17

TheThe ballball viscosityviscosity--metermeter isis basedbased onon

HopplersHopplers principleprinciple withwith aa fallenfallen

ballball.. ItIt isis usedused forfor thethe preciseprecise

measuringmeasuring ofof dynamicdynamic viscosityviscosity ofof

NewtonianNewtonian transparenttransparent fluidsfluids

withwith lowlow viscosityviscosity andand ofof dynamicdynamic

viscosityviscosity ofof gasesgases.. TheThe liquidsliquids

dynamicdynamic viscosityviscosity isis determineddetermined

withwith thethe scanscan speedspeed ofof thethe

standardstandard ballsballs insideinside thethe scaledscaled

tubetube.. TheThe HopplerHoppler viscosityviscosity--metermeter

cancan bebe usedused inin industrialindustrial

applications,applications, inin qualityquality control,control, asas

wellwell asas inin investigationsinvestigations..


10/17

The viscosity-meter is fully automatic

operated from a control panel, the

selection of any function being made with

the help of a keyboard. It has 18 rotationspeeds. This appliance measures viscosity

and temperature simultaneous (with the

help of an additional temperature

plunger). Being automatic there is a

permanently supervision of the settings,

alarm if the measuring is under or over the

torsion area. It has direct access for the

time measuring function (torsion time,

stop time).


11/17

The Engler conventional viscosity-meter is

used for measuring the viscosity in degrees

or Saybolt and Redwood for measuring in

seconds. It is an appliance intended for

determining the specific viscosity of tars

and its outcome products. This appliance

is used for comparing the specific viscosity

of oily and bitumen substances with same

viscosity as the water. The appliance

consists in a interior pot bounded by a

water-filled mantle (for thermaladjustment). The viscosity-meter includes

thermal regulator and an agitating device.


12/17

Study of honey viscosity variation with

temperature we'll do with electronicviscosimetric with vibrations SV.Viscosimetric main unit consists of twosensors with thin blades, container for thesample, the sensor unit and a display unit.

The SV-10 has two gold plated paddle typesensors 12mm in diameter that areimmersed into the sample to be measured.These paddles are in a tuning forkarrangement so when stimulated by anelectromagnetic drive the paddles vibrate ata constant frequency. The amplitude of

vibration is detected and sufficient currentis applied to the electromagnetic drive tomaintain a constant amplitude. The sampleviscosity causes the vibration to be dampedand the current required to maintain thevibration amplitude is measuredcontinuously, and converted into a viscosity

on the display.


13/17

The system takes 15 seconds to stabilise,

after which a continuous reading of

viscosity is displayed. The value actually

measured is dependent on the sampledensity. To get a value comparable with the

dynamic viscosity measured for example

by a disk and plate rotational viscometer,

the value displayed must be divided by the

density. There a number of ways of

measuring density. Weighing a measuredvolume from a micropipette, say 5mL, is

suitable for low viscosity solutions such as

aqueous buffers, and with care accuracies

of about 1% can be obtained. Some

balances have density accessories and thesecan be very accurate, but are a little time

consuming to set up. One of the most

convenient methods is the hand held

density meter. These are fast and accurate,

but more expensive than the other methods


14/17

By means of electronic viscometer with vibrations SV we

determined viscosity of honey bee by the followingprocedure:

We put the container on the table to determine device orientation

between the two blades of the container.

Was checked if the device is in normal working position

It weakens fixtures and keeping the front of the sensor unit , pulldown slightly, approaching the sample surface plate sensor.

We let down the handle security to protect sensitive plates

Adjustment screw rotates the head table so that the thin blades of the

two sensors to bee on a level with the surface to bee analyzed to

determine not appear inaccuracies.

In the manufacturing process the acquired data was achieved

interconnects the display unit and a unit of computer viscometer that

was installed with Windows Communication Tools Viscosity of which

were obtained in real time graphics of variation of temperature and

viscosity of honey.


15/17


16/17

We observed that if the temperature

increase the viscosity of the honeydecreases. Therefore result thattemperature is indirectlyproportional to honey viscosity.

In this table we present a part ofresults of measurement because wedid 300 notes every ten seconds :

Results and discutionsResults and discutionsResults and discutionsResults and discutionsResults and discutions

Results andResults and

discutions!!!discutions!!!


17/17

Thank you foryour attention!

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