Determination of Protein Content of Raw Fresh Cow’s Milk Using Dielectric Spectroscopy Combined with Chemometric Methods

et al. 2018

Int J of Food Sci Tech

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Summary Investigating the effect of homogenisation on the prediction performance of protein content by using near‐infrared (NIR) spectroscopy is helpful to improve protein determination precision. For this purpose, the influence of homogenisation on milk fat globules and NIR spectra was analysed firstly. Then, NIR spectra of eighty‐seven cow milk samples before and after homogenisation were obtained. Multiplicative scatter correction was used to do spectral pretreatment. Uninformative variable elimination based on partial least squares (UVE‐PLS) and successive projection algorithm was used to extract characteristic variables. Partial least squares regression (PLSR) and least squares support vector machine models were established. The results showed that homogenisation made milk fat globules be distributed evenly, decreased the size of fat globules and improved NIR spectral repeatability and prediction precision on protein content. The best model was PLSR‐UVE‐PLS, having good and excellent protein prediction ability for un‐homogenised milk (RMSEP = 0.06 g/100 g, RPD = 2.69) and homogenised milk (RMSEP = 0.04 g/100 g, RPD = 3.59), respectively.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of homogenisation on detection of milk protein content based on NIR diffuse reflectance spectroscopy

Wang

Guo

et al. 2018

Int J of Food Sci Tech

Self Cite

“…The dielectric properties of usual interest for practical applications are the dielectric constant, ε′, and the dielectric loss factor, ε′′, the real and imaginary parts, respectively, of the complex permittivity relative to free space, ɛ* = ɛ ′ ‐ j ɛ ′′ . Many studies have reported that the dielectric properties of agricultural products and foods, such as fruits (Barba & Lamberti, ; Guo et al ., ; Ling et al ., ), vegetable powders (Ozturk et al ., ), meat (Abidin et al ., ), eggs (Lin et al ., ; Soltani et al ., ), are dependent not only on the frequency of the electric field and the temperature of the materials, but also on their chemical compositions, such as water (Barba & Lamberti, ; Torrealba‐Melendez et al ., ), salt (Wang et al ., ; Zhang et al ., ), protein (Feng et al ., ; Zhu et al ., ), fat (Zhu et al ., ), sugar (Franco et al ., ), alcohols (Khaled et al ., ), and so on.…”

Section: Introductionmentioning

confidence: 99%

“…Many studies have reported that the dielectric properties of agricultural products and foods, such as fruits (Barba & Lamberti, 2013;Guo et al, 2013;Ling et al, 2015b), vegetable powders (Ozturk et al, 2016), meat (Abidin et al, 2016), eggs (Lin et al, 2014;Soltani et al, 2015), are dependent not only on the frequency of the electric field and the temperature of the materials, but also on their chemical compositions, such as water (Barba & Lamberti, 2013;Torrealba-Melendez et al, 2016), salt Zhang et al, 2015), protein (Feng et al, 2015;Zhu et al, 2016), fat , sugar (Franco et al, 2015), alcohols (Khaled et al, 2016), and so on.…”

Section: Introductionmentioning

confidence: 99%

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

Liu

2018

Int J of Food Sci Tech

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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.

“…Some studies on dielectric properties of food materials and agricultural products, such as alcohols (Khaled, Novas, Gázquez, García, & Manzano‐Agugliaro, ), sugar (Franco, Yamamoto, Tadini, & Gut, ), honey (Guo, Liu, Zhu, & Wang, ), vegetable powders (Ozturk, Kong, Trabelsi, & Singh, ; Zhu & Guo, ), fruits (Barba & Lamberti, ), meats (Castro‐Giráldez, Dols, Toldr, & Fito, ; Tanaka, Mallikarjunan, & Hung, ), eggs (Lin, Zhang, Fang, & Liu, ; Soltani, Omid, & Alimardani, ), and so on, have shown that the dielectric properties are dependent on frequency and temperature. What is more, the dielectric properties also depend on the compositions of food, such as fat (Zhu, Guo, & Liang, ), protein (Zhu, Guo, Kang, Kong, & Zhu, ), water (Barba & Lamberti, ; Torrealba‐Melendez, Sosa‐Morales, Olvera‐Cervantes, & Corona‐Chavez, ), etc.…”

Section: Introductionmentioning

confidence: 99%

Dielectric properties of raw milk as influenced by frequency, salts, and salt contents

J Food Process Engineering

Liu

2018

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To understand the effect of salts and salt contents on dielectric properties (dielectric constant ε′ and dielectric loss factor ε″) of milk, dielectric properties of raw cow's milk samples at the total salt content (in mass) of 0.75–0.87%, 0.75–0.93%, and 0.75–0.90% by adding NaCl, MgCl2, and KCl, respectively, were obtained from 19 to 3,000 MHz at 25 °C using an impedance analyzer. The results showed that ε′ decreased with increasing frequency, and ε″ changed with “V” shape and had minimums at about 1,500 MHz. At a given frequency and the same salt addition level in molar, the milk added with NaCl and MgCl2 had the smallest and the biggest ε″, respectively. At about 40 MHz, ε′ had a very good positive linear relationship with the total salt content of milk, whose coefficients of determination were 0.96, 0.98, and 0.95 for NaCl, MgCl2, and KCl, respectively. ε″ increased linearly with increasing total salt contents with the coefficients of determination higher than 0.99 below about 900 MHz and higher than 0.86 above 900 MHz no matter for which salt. Practical applications This work shows that there were linear relationships between dielectric properties and total salt contents. The study is helpful to understand the influence of salts and salt content on dielectric properties of raw cow's milk, and it offers useful information for developing portable salt detector based on dielectric properties in the future.