proiect miere
Transcript of proiect miere
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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
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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?!?
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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
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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.
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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.
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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.
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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.
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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.
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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..
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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).
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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.
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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.
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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
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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.
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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!!!
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Thank you foryour attention!