Temperature-Dependent Dielectric Properties of Raw Cow’s and Goat’s Milk from 10 to 4,500 MHz Relevant to Radio-frequency and Microwave Pasteurization Process

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Summary Dielectric properties (dielectric constant ε′ and dielectric loss factor ε′′) of whole milk and skim milk with the lactose content of 4.56–6.44% and 4.57–6.47%, respectively, were measured over the frequency range of 20–4500 MHz at 25 °C using a vector network analyzer. The results showed that ε′ decreased with increasing frequency, and ε′′ changed with V shape and its minimum was noted at about 2000 MHz. Whole milk had lower dielectric properties than skim milk at almost same lactose content and a given frequency. ε′ had weak positive linear relationship with lactose content for whole milk, but had negative linear relationship for skim milk. No matter for which milk, ε′′ had very good negative linear relationship with lactose content below 1000 MHz and had good positive linear relationship above 2300 MHz. The study provides information on developing rapid lactose detector for milk in future.

Section: Resultsmentioning

confidence: 99%

Effect of lactose content on dielectric properties of whole milk and skim milk

Liu

Zhu

2018

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“…Traditionally, food is heated by conduction and/or convection. In the last decade, applications of infrared radiation, microwaves and radio waves for heat treatment are continuously increasing (Calabrò & Magazù, ; Sun, ; Benlloch‐Tinoco et al ., ; Chong et al ., ; Guo & Zhu, ; Igual et al ., ; Li & Pan ; Pina‐Perez et al ., ; Wang et al ., ; Zhao et al ., ; Zhu et al ., .…”

Section: Introductionmentioning

confidence: 99%

Microwave vs. convection heating of bovine Gluteus Medius muscle: impact on selected physical properties of final product and cooking yield

Półtorak

Wyrwisz

Moczkowska

et al. 2015

Summary The aim of this study was to investigate the impact of two convection–microwave heating (M100 and M30) on texture and colour properties, cooking yield and thermal shrinkage of bovine product (gluteus medius muscle) as compared with conventional roasting at constant temperature (P180 and P80) and roasting with ΔT program (Δ80 and Δ40). The product processed by the M100 method was characterised by high shear force (WBSF) and high compression force (TPA). The reduction of microwave intensity to 30% (roasting M30) could improve the tenderness of final product. In addition, microwave heating at the intensity of 30% shortened the roasting time, and the produced sample exhibited comparable process loss and heat shrinkage extent compared to those treated by the high‐temperature conventional roasting method (P180). The study indicated that combining of convection and low‐intensity microwave heating could be successfully used in catering business for beef roasting due to the shorter cooking time, reduced cooking loss and higher tenderness of meat.

“…above 2000 MHz. The changed trend of ε″ with frequency has also been noted on other foods and agricultural products, such as egg (Soltani et al ., ), apple juices (Siguemoto & Gut, ), bean (Torrealba‐Melendez et al ., ), nuts (Wang et al ., ; Ling et al ., ), milk (Zhu et al ., ) and watermelon (Guo et al ., ).…”

Section: Resultsmentioning

confidence: 99%

Effect of solids‐not‐fat content on dielectric properties of skim milk

Liu

Zhu

2018

Self Cite

Summary Dielectric constant (ε′) and loss factor (ε″) of skim milk samples at different total solids‐not‐fat contents were measured over the frequency range of 20–4500 MHz at 25 °C using a vector network analyser. The results showed that ε′ of skim milk decreased as frequency increased, and ε″ changed from decreasing to increasing and had minimums at about 2000 MHz. There was a linear relationship between ε′ and solids‐not‐fat content with correlation coefficient higher than 0.940 below 50 MHz and keeping at −0.990 above 150 MHz. ε″ had positive linear relationship with solids‐not‐fat content, and their correlation coefficient was higher than 0.970 at all investigated frequencies. Penetration depth of electromagnetic wave in milk decreased as increased frequency or solids‐not‐fat content. The study is helpful to know the relationship between solids‐not‐fat content and dielectric properties, and it provides information for developing solids‐not‐fat detector could be used in on‐line detection for skim milk production.