Experimental study on in-situ viscosity measurement of milk fermenting to yogurt by laser-induced capillary wave method

Hiromi Iwashima, Yuji Nagasaka

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We have developed a new technique for measuring liquid viscosity using a pulsed carbon dioxide laser as a heating source. In this method, interfering laser beams heat the liquid surface and generate a laser-induced capillary wave (LiCW) caused by spatially sinusoidal temperature distribution. The temporal behavior of LiCW is detected by a diffracted probe beam at the heating area. The LiCWdynamics provide information on the thermophysical properties of the liquid, such as viscosity and surface tension. In this paper, we have (1) measured nine Newtonian liquid samples with viscosity ranging from 0.304 ≃ 7080 mPa•s and obtained viscosity within approximately ±10% deviation from the reference values, and (2) measured the apparent viscosity of milk fermenting to yogurt and obtained signals that change significantly during fermentation. The relative increase of apparent viscosity was more than 100-fold, and this order of magnitude agreed with previous measurements acquired by conventional methods.

Original languageEnglish
Pages (from-to)51-60
Number of pages10
JournalHigh Temperatures - High Pressures
Volume37
Issue number1
Publication statusPublished - 2008 Dec 1

Keywords

  • Food manufacturing process
  • Laser-induced capillary wave method
  • Milk
  • Surface tension
  • Viscosity
  • Yogurt

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Physical and Theoretical Chemistry

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