We review the literature covering the evolution of amino acid, protein, lipid and carbohydrate analysis in food samples by electromigration techniques over the last 20 years.

This Research Paper addresses the hypothesis that the type of dulce de leche formula affects formation of 5-hydroxymethylfurfural (HMF) during production and storage. Milk and sweetened condensed milk are products in which the Maillard reaction (MR) defines important characteristics such as colour and taste. There are few studies on the effects of pH, time, concentration, and sugar type on the formation of HMF or other MR markers in DL. Four formulas (varying in the addition of sodium bicarbonate and the type of sugar) were analysed for moisture, lipid, protein, ash, carbohydrate, water activity (Aw), and soluble solids. We found low variability in physicochemical and compositional attributes, but an elevation of HMF indices throughout the manufacturing. We determined that the addition of glucose and the use of relatively high concentrations of sodium bicarbonate caused these HMF indicator increases. These results inform DL research and production by the dairy industries and the scientific community, and highlight the importance of control in manufacturing.

This paper describes the development, evaluation, features and applications of Chromophoreasy, an alternative Excel-based program for recognition and integration of chromatographic and electrophoretic peaks. The proposed recognition is made according to parameters adjustable by the analyst, such as time range, noise smoothing window size and slope/curvature sensitivity. During integration, retention/migration time, area, height, half-height width, plate numbers, asymmetry factor, US Pharmacopeia tailing factor, resolution and statistical moments are determined. A chromatogram/electropherogram is plotted along with the found baselines. The effect of peak shape (heights and symmetries) and baseline slope over accuracy was evaluated and the precision of recognition/integration was investigated under several simulated conditions, with varied signal-to-noise levels, smoothing modes and smoothing window sizes. Data from liquid and gas chromatography, capillary electrophoresis and electrochromatography techniques with refractive index, flame ionization, capacitively coupled contactless conductivity (lab-made) and ultraviolet absorbance detections, respectively, were treated, illustrating the broad applicability of the proposed program for standard and sample analysis. Statistically similar results were obtained, when compared with other commercial software, showing it to be a simple, practical and reliable tool for general use in the separation area.

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...