Frequency- and temperature-dependent dielectric properties of fruit juices associated with pasteurization by dielectric heating

Zhu, Xinhua; Wu, Xiaoling

doi:10.1016/j.jfoodeng.2011.10.005

Cited by 97 publications

(87 citation statements)

References 28 publications

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“…Thus, we observed slight fluctua- tion in values of dielectric properties of solid samples at higher temperatures. Similar minor fluctuations in dielectric data were found in the literature for various products, such as chestnut flour (Zhu et al, 2012b), fruit juices (Zhu et al, 2012a), and soy flour (Terigar et al, 2010). For both whey protein gel and mashed potato, the dielectric constant values of frozen samples were much lower than those of room, warm, and hot temperature samples.…”

Section: Dielectric Constants Of Whey Protein Gel and Mashed Potatosupporting

confidence: 82%

“…Penetration depth is usually defined as the distance at which the power drops to 36.8% of its value at the surface of the material. It is an important concept to evaluate whether an electromagnetic field at a certain frequency can provide relatively uniform heating in a given food product (Zhu et al, 2012a). The penetration depth (D p ) can be calculated as (Metaxas and Meredith, 1983):…”

Section: Penetration Depthmentioning

confidence: 99%

“…When some part of the frozen food is thawed, the dielectric loss factor of the thawed regions dramatically increases, and those regions can be heated quickly. This nonuniform heating phenomenon due to the loss factor is also similarly explained as "thermal runaway" (Zhu et al, 2012a). This phenomenon challenges the development of frozen foods for microwave heating with good cooking performance in terms of heating uniformity.…”

Section: Dielectric Loss Factors Of Whey Protein Gel and Mashed Potatomentioning

confidence: 99%

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Temperature-Dependent Dielectric and Thermal Properties of Whey Protein Gel and Mashed Potato

Chen¹,

Pitchai²,

Birla³

et al. 2013

Trans.ASABE

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Section: Dielectric Constants Of Whey Protein Gel and Mashed Potatosupporting

confidence: 82%

Section: Penetration Depthmentioning

confidence: 99%

Section: Dielectric Loss Factors Of Whey Protein Gel and Mashed Potatomentioning

confidence: 99%

See 1 more Smart Citation

Temperature-Dependent Dielectric and Thermal Properties of Whey Protein Gel and Mashed Potato

Chen¹,

Pitchai²,

Birla³

et al. 2013

Trans.ASABE

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“…It was found that the dielectric properties of those liquids allow for their identification. Next, solutions of the acetic acid and vinegar were studied by Bohigas and Tejada (2009) in the frequency range 1-20 GHz, while examinations of the dielectric properties of various fruit juices (apple, pear, orange, grape and pineapple) for frequencies 20-4 500 MHz at temperatures 15-95°C were conducted by Zhu et al (2012). It was observed that the real part of the dielectric permittivity decreases linearly with the increase in temperature.…”

Section: Dielectric Properties Of Liquid Materials Of Agricultural Ormentioning

confidence: 99%

Dielectric spectroscopy in agrophysics

Skierucha¹,

Wilczek²,

Szypłowska³

2012

International Agrophysics

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A b s t r a c t. The paper presents scientific foundation and some examples of agrophysical applications of dielectric spectroscopy techniques. The aim of agrophysics is to apply physical methods and techniques for studies of materials and processes which occur in agriculture. Dielectric spectroscopy, which describes the dielectric properties of a sample as a function of frequency, may be successfully used for examinations of properties of various materials. Possible test materials may include agrophysical objects such as soil, fruit, vegetables, intermediate and final products of the food industry, grain, oils, etc. Dielectric spectroscopy techniques enable non-destructive and non-invasive measurements of the agricultural materials, therefore providing tools for rapid evaluation of their water content and quality. There is a limited number of research in the field of dielectric spectroscopy of agricultural objects, which is caused by the relatively high cost of the respective measurement equipment. With the fast development of modern technology, especially in high frequency applications, dielectric spectroscopy has great potential of expansion in agrophysics, both in cognitive and utilitarian aspects.K e y w o r d s: agrophysics, dielectric spectroscopy, food quality INTRODUCTIONAgrophysics is a specialized scientific field derived from the branch of the agricultural sciences (Micha³ek, 2006). Its aim is to apply physical methods for studies of properties of materials and processes occurring in production and processing of crops and food of agricultural origin. Dielectric properties of all materials existing in Nature are dependent on their molecular structure. Specifically, they depend on the distribution of electric charges, which are either constantly embedded within the molecules or become temporarily induced on their surfaces. It is also known that the molecular structure of objects determine their physical and chemical properties. Therefore, one may suppose that the dielectric properties of mixtures of various molecules constituting a given material will uniquely identify it. It means that dielectric properties can successfully diversify physical and chemical properties of a tested material. This idea is presented in Fig. 1. The crucial point of the application of the dielectric spectroscopy measurement techniques in agrophysics is the utilization of their advantages for rapid and non-destructive assessment of the quality of the agricultural objects. It may be done by searching for dependencies between the dielectric properties and other physical and chemical properties of tested materials of agricultural origin.Behaviour of any material in the electric field is unique, because of the unique molecular structure of each material. On the other hand, physical and chemical properties of materials determine their quality, which in the case of food products is closely related to their commercial and nutritional value. Therefore, it is reasonable to assume that the dielectric properties, uniquely describing each...

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“…São observados estudos mais comuns em alimentos líquidos, como sucos de uva, abacaxi, maça, pêra e laranja (Zhu et al, 2012), mel (Guo et al, 2011), leite, bebidas de soja (Coronel et al, 2008), mas podemos observar estudos em alimentos semissólidos, como purê de batata ( Guan et al, 2004), manteiga (Ahmed et al, 2007) e queijo (Everard et al, 2005). Porém não foi observado nenhum estudo sobre as propriedades dielétricas sobre o purê de manga.…”

Section: Introductionunclassified

PROPRIEDADES DIELÉTRICAS DO PURÊ DE MANGA CRU NAS FREQUÊNCIAS DE 0,5 a 3 GHz ENTRE AS TEMPERATURAS DE 10 E 90º C

Cruz¹,

Gut²,

Tadini

2015

Anais Do XX Congresso Brasileiro De Engenharia Química

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RESUMO -As propriedades dielétricas do purê de manga cru foram avaliadas utilizando a técnica de medição de cabo coaxial de ponta aberta. Enfatizou as frequências comerciais, entre 915 e 2450 MHz, para o aquecimento em microondas, utilizando a correlação das propriedades com a temperatura. Para a permissividade (ε'), houve uma relação inversa com a temperatura, devido à agitação térmica das moléculas interferirem na polarização das moléculas de água. Em baixas temperaturas, a permissividade relativa obteve as maiores diferenças entre a primeira e última frequência. Observando a temperatura de 10 ºC e a frequência de 500 MHz encontra-se 76,77 e na frequência de 3000 MHz, o valor de 67,19, verificando uma variação de aproximadamente 7,48, enquanto nas temperaturas mais altas, as variações entre as frequências foram diminuindo, seguindo à estabilidade com o aumento da temperatura. Nas frequências comerciais, o fator de perda (ε") apresentou oscilações com o aumento da temperatura.

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Frequency- and temperature-dependent dielectric properties of fruit juices associated with pasteurization by dielectric heating

Cited by 97 publications

References 28 publications

Temperature-Dependent Dielectric and Thermal Properties of Whey Protein Gel and Mashed Potato

Temperature-Dependent Dielectric and Thermal Properties of Whey Protein Gel and Mashed Potato

Dielectric spectroscopy in agrophysics

PROPRIEDADES DIELÉTRICAS DO PURÊ DE MANGA CRU NAS FREQUÊNCIAS DE 0,5 a 3 GHz ENTRE AS TEMPERATURAS DE 10 E 90º C

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