Standardization of the Harland-Ashworth Test for Whey Protein Nitrogen

Kuramoto, Satoshi; Jenness, Robert; Coulter, S.T.; Choi, R.P.

doi:10.3168/jds.s0022-0302(59)90520-x

Cited by 41 publications

(19 citation statements)

References 2 publications

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“…22 (2) em que: x e é o valor médio experimental (amostra); t é o valor de t student com α = 0,05 considerando o grau de liberdade do sistema; b 1 é o valor de inclinação da reta do modelo; s é a raiz da soma quadrádica dos resíduos do modelo; q é o número de réplicas em cada nível do modelo; n é o número de observações total do modelo; x i é o valor de concentração do nível i do modelo; x m é o valor médio teórico dos níveis do modelo.…”

Section: Quantificação Dos Indicadores De Tratamento Térmico Estudadosunclassified

“…1 Especificamente estas duas modificações químicas causadas pela ação do calor geram compostos capazes de serem determinados através de métodos espectrofotométricos, 2,3 permitindo monitorar e controlar a severidade do tratamento térmico aplicado ao produto.…”

Section: Introductionunclassified

“…A metodologia proposta por Kuramoto et al 2 para determinação do índice de soroproteína não desnaturada ou whey protein nitrogen index (WPNI) via turbidimetria utiliza o princípio de "salting out" com adição de cloreto de sódio em excesso. Sabe-se que ao aumentar a força iônica de um meio há a tendência na redução da capacidade solvente da água e, consequentemente, da espessura da dupla camada elétrica que envolve as proteínas.…”

Section: Introductionunclassified

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Spectrophotometric Determination of Wpni and HMF in Uht Milk Through the Principal Components Analysis

Neves¹,

Silva²,

Oliveira³

2016

Química Nova

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SPECTROPHOTOMETRIC DETERMINATION OF WPNI AND HMF IN UHT MILK THROUGH THE PRINCIPAL COMPONENTS ANALYSIS.During heat treatment milk suffers changes among which whey proteins insolubility and Maillard reaction can be monitored using spectrophotometric methods by determining the whey protein nitrogen (WPNI) and 5-hydroxymethylfurfural (HMF). The aim of this work was the evaluation of heat treatment in commercial UHT milk samples through HMF and WPNI determination by spectrophotometric methods in visible region, using chemometric tools in data analysis. The regression models were fitted and statistical assumptions were tested. The WPNI confidence interval (CI) was (0.91; 3.73) mg mL -1 showing the heat treatment severity and classifying the samples as "medium heat treatment" according to American Dairy Products Association. For free HMF index, the CI were: (2.39; 3.27) and (6.01; 6.89) µmol L -1 for regular and low lactose content samples, respectively; while these two samples group presented CI of (11.67; 12.39) and (132.28; 143.22) µmol L -1 for total HMF index, respectively; showing the influence of lactose content in total HMF index. Descriptive statistical analysis associated with principal component analysis demonstrated a lack of standardization in the current Brazilian UHT process. The spectrophotometric methods allowed obtaining further inferences about the product quality associated to its heat treatment.Keywords: Maillard reaction; denaturation; chemometric; quality control. INTRODUÇÃODurante o processamento térmico o leite sofre modificações devido à ação do calor, dentre as quais tem-se a insolubilização das soroproteínas e a reação entre proteínas e lactose, denominada reação de Maillard (RM).1 Especificamente estas duas modificações químicas causadas pela ação do calor geram compostos capazes de serem determinados através de métodos espectrofotométricos, 2,3 permitindo monitorar e controlar a severidade do tratamento térmico aplicado ao produto.Métodos espectrofotométricos têm sido usualmente utilizados para determinação de alguns constituintes químicos em matrizes alimentícias 4-11 devido à fácil aplicação, eficácia e eficiência aceitáveis, e baixo custo quando comparados a métodos analíticos mais sofisticados como, por exemplo, cromatografia à líquido de alta eficiência (CLAE), 12,13 cromatografia a gás (CG), 14-16 cromatografia por fluido supercrítico (CFS) 17-19 e eletroforese capilar (EC) 20-23 associados a detectores compatíveis com cada sistema de separação.A metodologia proposta por Kuramoto et al. 2 para determinação do índice de soroproteína não desnaturada ou whey protein nitrogen index (WPNI) via turbidimetria utiliza o princípio de "salting out" com adição de cloreto de sódio em excesso. Sabe-se que ao aumentar a força iônica de um meio há a tendência na redução da capacidade solvente da água e, consequentemente, da espessura da dupla camada elétrica que envolve as proteínas. A redução de tais efeitos estabilizadores proporciona uma efetiva perda de solubilidade protéica gerando preci...

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Section: Quantificação Dos Indicadores De Tratamento Térmico Estudadosunclassified

Section: Introductionunclassified

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Spectrophotometric Determination of Wpni and HMF in Uht Milk Through the Principal Components Analysis

Neves¹,

Silva²,

Oliveira³

2016

Química Nova

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“…The amount of integrated calories added to type N was assumed to be 1.0. The amount of integrated calories added to the other skim milk powders were expressed as the relative content to that of type N. * Whey protein nitrogen index was determined according to the method of Kuramoto, et al (1959). Whey protein nitrogen index in SH was regarded as 100%.…”

Section: Methodsmentioning

confidence: 99%

Effects of Heating Conditions on Physicochemical Properties of Skim Milk Powder during Production Process

Miyamoto

Matsumiya

Kubouchi

et al. 2009

FSTR

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To investigate the effects of production-related heat treatments on physicochemical properties of skim milk powder, four kinds of skim milk powder were prepared under different heating conditions. The degree of heating was expressed as the integrated caloric content added to the powders. The four skim milk powders were dispersed in water, and the physicochemical properties of them were compared. Solution turbidity increased with an increase in integrated caloric content, but the protein content in the supernatant decreased; the latter characteristic indicated that severe heating conditions resulted in aggregate formation of denatured whey protein molecules. The content of sulfhydryl groups and surface hydrophobicity of skim milk solutions were closely related to the heating conditions in the production process. SDS-PAGE analysis revealed that β-lactoglobulin and α-lactalbumin were main proteins involved in aggregate formation. The powder that had been treated with the most severe heating condition was found to be the most suitable for making bread.

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“…Of the last two types, the SH type received more calories. The degree of denaturation of each of the four skimmed milk powders was expressed as whey proteinnitrogen index values, 19) as shown in Table 1. Rennet (Fromase 2,200 TL) was obtained from DSM Food Specialties (Delft, Netherlands).…”

Section: Methodsmentioning

confidence: 99%

Rennet-Induced Aggregation and Curd Formation from Skimmed Milk Powders Prepared under Different Sterilizing Conditions

Miyamoto

Matsumiya

Kubouchi

et al. 2009

Bioscience, Biotechnology, and Biochemistry

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Standardization of the Harland-Ashworth Test for Whey Protein Nitrogen

Cited by 41 publications

References 2 publications

Spectrophotometric Determination of Wpni and HMF in Uht Milk Through the Principal Components Analysis

Spectrophotometric Determination of Wpni and HMF in Uht Milk Through the Principal Components Analysis

Effects of Heating Conditions on Physicochemical Properties of Skim Milk Powder during Production Process

Rennet-Induced Aggregation and Curd Formation from Skimmed Milk Powders Prepared under Different Sterilizing Conditions

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