Dielectric properties relevant to the characterization, quality monitoring and processing of food and biodegradable films

• Grant number: 13/19359-9
• Support Opportunities: Research Grants - Visiting Researcher Grant - International
• Start date: February 17, 2014
• End date: December 15, 2014
• Field of knowledge: Agronomical Sciences - Food Science and Technology - Food Engineering
• Principal Investigator: Paulo José do Amaral Sobral
• Grantee: Paulo José do Amaral Sobral
• Visiting researcher: Alberto Manuel Carneiro Sereno
• Visiting researcher institution: Universidade do Porto (UP), Portugal
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated research grant: 13/07914-8 - FoRC - Food Research Center, AP.CEPID

Abstract

The dielectric properties of foodstuffs and other biological materials is an area of expertise with a significant potential for the development of new methods of characterization, assessing the quality and process monitoring of food using nondestructive techniques. Another field of use, already with wide use for synthetic polymers is the characterization of molecular mobility in amorphous solids, including identifying the occurrence of phase transitions and to correlate these results with those obtained by differential scanning calorimetry for some relevant food materials. In summary, the project's main objectives are the study of the molecular mobility of amorphous solids, identify biochemical markers enabling the use of dielectric properties of food for the development of non-destructive sensors that can be used both for monitoring quality during processing as for evaluation of quality along the food chain and the study of new uses of high frequency alternating electric fields (RF and MW) for processing fruit and vegetables, as an alternative to conventional thermal processes. To measure the dielectric properties of polymeric films and the location of glass transition, a probe forming a parallel plate capacitor is used, leaving the film constituting the dielectric. The films are conditioned for temperature (in the range containing the glass transition temperature) and humidity. For each test temperature a sweep of frequencies between 10Hz and 1MHz will be made. The measurement of the dielectric properties in the RF and MW ranges are performed using a coaxial probe in a frequency range of 10MHz to 20GHz. The probes are connected to a network analyzer with software that calculates the dielectric constant, loss factor and loss tangent. The spectra of the dielectric constant (e') and loss factor (e'') will be adjusted to suitable mathematical models, namely the equation of Havriliak/Negami, using a multiparameter least squares nonlinear regression. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

SILVA, VIVIAN LARA; SERENO, ALBERTO M.; DO AMARAL SOBRAL, PAULO JOSE. Food Industry and Processing Technology: On Time to Harmonize Technology and Social Drivers. FOOD ENGINEERING REVIEWS, v. 10, n. 1, p. 1-13, MAR 2018. (13/19359-9, 13/07914-8)