52


At the beginning of the measurement, the viscosity of the mayonnaise is zero because the measurement started approximately half a centimetre above the sample (Figure 13). Then the spindle rotates through the sample, which leads to a viscosity plateau after a short period of time. Within this plateau, the viscosity can be averaged. The selected mayonnaise has an average viscosity of 14,830 mPa·s (74.2 % torque). The goal of production is that mayonnaise has a proper thickness for the application regardless of the fat content.


References 1. Mezger, T. 2011. The Rheology Handbook. 3rd revised edition. Hanover: Vincentz Network. 2. Newton, I. 1687. Philosophiae naturalis principia mathematica (“Principia”). London.


3. ISO 3219:1994-10. 1994. Plastics – Polymers/Resins in the Liquid State or as Emulsions or Dispersions – Determination of Viscosity Using a Rotational Viscometer with Defi ned Shear Rate.


4. Genovese, D. B., and M. A. Rao. 2005. “Components of Vane Yield Stress of Structured Food Dispersions.” Journal of Food Science, 70(8): E498–E504.


Figure 13. Viscosity measurement of mayonnaise with a rotational viscometer equipped with a motorised stand adapter and T-bar spindle. The viscosity values of the last 30 s of the measurement have been averaged.


It moves the spindle during the measurement up- and downwards within the sample at a slow speed. It eliminates the so-called ‘channelling’ problem. Any spindle that rotates constantly at the same height will create an air channel within the sample, which will lead to meaningless viscosity values as the sample is not in contact with the spindle anymore. The moving viscometer head with T-bar spindles eliminates this problem by continuously measuring the intact sample due to the helical spindle movement.


Sustainable Tubes from Cooking Oil Waste


able. Compliant. measurement


The new generation of tubes ‘Eppendorf Tubes®


(Accountability, Consistency, Transparency). More information online: ilmt.co/PL/M2aV


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Eppendorf is no longer only focusing only on the development of new products, but also on new manufacturing materials. In line with the ‘Reduce, Reuse, Recycle’ concept, the main goal is to produce polymer products in a much more sustainable way without compromising the guaranteed product quality and performance needed in increasingly demanding research.


BioBased’ is made from 90% ‘bio-circular’, renewable-based feedstook (recycled e.g. from


food oil wastes and residues) plus 10% fossil-based feedstock. Thus, these tubes in the sizes 5.0 mL, 15 mL, 25 mL and 50 mL with screw cap are made of certifi ed polypropylene based on renewable, recycled raw materials and are called ‘BioBased’.


The Consumable production centre in Oldenburg/Germany meets the requirements of the ISCC PLUS (International Sustainability & Carbon Certifi cation) certifi cation system. Additionally, sustainability of the tubes is certifi ed by ‘My Green Lab®


’ with ‘ACT Certifi cates’


Ultrasonic Cleaning Solutions for Laboratory Applications


The cavitation phenomenon consists of the formation and growth of millions of microscopic bubbles under a low-pressure stage, produced into the ultrasonic bath due to a high power transducer 40kHz. These bubbles break in all directions and attack every surface in contact with water, erasing dirt, impurities and pollutants when contacting with the materials or pieces into the bath. This phenomenon allows cleaning all kind of items without the need of disassembling, due to all the surfaces being in contact with the liquid. The heating function of the unit allows the acceleration of this cleaning process.


Wiggens presents two series of standard ultrasonic cleaners with reliable quality and useful features, which allows the users a wide range of cleaning applications such as lab materials, medical instruments, dental prosthesis, optics, industrial items, jewelleries, also the degasifi cation or liquid dissolution and compact substances disaggregation.


The following are the standard working volumes supplied: 3, 6, 10 and 22 litres, and bespoke volumes can be ordered for different applications. All functions can be viewed and monitored on a large and clear touch screen display. The parameters can be set by screen touching, including the ultrasonic working power (40% to 100%), bath temperature (20°C to 80°C), timer and warning function for safety.


All models are equipped with lids and trays that allow the parts they introduce to be directly cleaned without damaging the transducers and for easy handling.


In addition to the standard ultrasonic cleaners, Wiggens also offers the ultrasonic cleaners with special added functions. The Shaking Ultrasonic Cleaner is a good example, which means that the sample can be pre-homogenised at a specifi c shaking speed, and then fi nal homogenisation can be achieved in a very short time, using ultrasonic power These two procedures can be carried out simultaneously or separately. Another added function is an ultrasonic cleaner with cooling for use in pathology and analysis labs, where the temperature of bath can be maintained at 10°C to 40°C even with the ultrasonic power generating heat continuously.


Contact Wiggens to accelerate your cleaning process. More information online: ilmt.co/PL/9D59


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Interested in publishing a Technical Article?


Contact Gwyneth on +44 (0)1727 855574


or email: gwyneth@intlabmate.com


INTERNATIONAL LABMATE - FEBRUARY 2023


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