Paulo Henrique Fonseca da Silva

Analysis of amino acids, proteins, carbohydrates and lipids in food by capillary electromigration methods: a review

A review of the literature covering the evolution of amino acid, protein, lipid and carbohydrate analysis in food samples by electromigration techniques over the last 20 years is presented. The manuscript summarizes different modes, including capillary zone electrophoresis, micellar electrokinetic chromatography, capillary electrochromatography, capillary gel electrophoresis, capillary isotachophoresis, non-aqueous (or nonaqueous) capillary electrophoresis, capillary isoelectric focusing and microfluidic chip electrophoresis, employing different detection systems, such as ultraviolet-visible absorption, laser-induced fluorescence, mass spectrometry, amperometric detection, and capacitively coupled contactless conductivity detection. Briefly, the present review evidences that CE is a very interesting analytical separation technique for food analysis, offering short analysis times and versatility in a simple sample preparation step as inherent advantages compared to classical chromatographic methodologies, which make it a separation technique that is very attractive for quality control in industry and government agencies.

Alternative method for lactulose quantification in the presence of lactose in milk using HILIC with refractive index detection

An alternative chromatographic method, HILIC-RID, has been developed for lactulose quantification in the presence of lactose in milk samples. Eighteen commercial UHT milk samples were analyzed. The best separation results were achieved with a mobile phase composed of acetonitrile–water (75 : 25) using an isocratic flow of 1 mL min−1. The limits of detection and quantification were 22.68 ± 8.10 and 75.61 ± 27.01 mg L−1, respectively. Recovery ranged from 98.5 to 103.6% for three lactulose fortification levels. All samples presented low coefficients of variation (0.31–2.16%) for lactulose quantification, indicating good method reproducibility. ANOVA test showed all samples differ from the others at the 99% confidence level and allowed an inference about the lack of uniformity in Brazilian UHT milk. A lactulose amount above 600 mg L−1 found in a specific sample indicated a possible recirculation occurrence during its processing. The results attested the applicability of the HILIC-RID method as an alternative tool for quality control, heat damage investigation and food inspection.

Study of Thermal Behaviour of Milk Protein Products Using a Chemometric Approach

This study deals with the evaluation of the behavior of viscosity evolution of the Milk Protein Products (MPPs) solutions in different concentrations used in different conditions of thermal processing by means of Rapid Visco Analyzer (RVA). Skimmed milk powder (SMP), whey protein Original Research Article Stephani et al.; BJAST, 7(1): 62-83, 2015; Article no.BJAST.2015.126 63 concentrate (WPC), milk protein concentrate (MPC), whey powder (WP) and demineralized whey powder (DWP) were analyzed; the evaluated solid-liquid ratio solutions were 0.1 g∙g -1 to 0.45 g∙g -1 of dry solids in water (DSW) for the MPC, 0.1 g∙g -1 to 0.4 g∙g -1 of DSW for the WPC and 0.5 g∙g -1 to 0.8 g∙g -1 of DSW for SMP, WP and DWP. Brazilian industrial heat treatment set ups were used, with temperatures ranging from 65°C to 95°C and retention time from 5 to 30 minutes. The results were interpreted according to the viscosities during heating and cooling, being possible to optimize the MPPs different parameters conditions with the interpretations of the viscographic profiles based on the thermal behavior of proteins, especially for the SMP, MPC and WPC. The data showed similarity in viscographic characteristics of the solutions when evaluated at 65°C for 30 minutes, at 85°C for 15 minutes and 95°C for 5 minutes, for the MPC and WPC at 95°C for 5 minutes, all of them for different concentrations of proteins in water.

Cow’s Milk Protein Allergy and Lactose Intolerance

Abstract Allergies to cow milk and lactose intolerance are problems that are increasingly being diagnosed by patients. This chapter addresses the main characteristics of both conditions, presenting their concepts, physiopathology, symptoms, diagnosis, and possible treatments for patients, aiming their recovering. Finally, the impacts and consequences of the exclusion diet are presented.

Lactulose determination in UHT milk by CZE-UV with indirect detection

Lactulose is not found naturally in milk, but it has been detected in small quantities in heated dairy products. It can therefore be used as an indicator of the severity of heat treatment for dairy products. This study proposes an alternative method for lactulose quantification in milk using capillary zone electrophoresis with ultraviolet detection (CZE-UV). The investigation used several Brazilian UHT milk samples, and various sample pretreatment methods and injection conditions were considered. Optimal separation results were achieved using Carrez clarification solutions. Low detection and quantification limits were obtained, and good precision and high recovery rates indicated the applicability of the method for analysis of milk. Due to matrix effects, single-point standard addition was used for lactulose quantification. High lactulose concentrations (>1000 mg L-1) suggested that recirculation may have occurred during milk processing. The findings demonstrate that the CZE-UV method is a viable alternative for quality process control.

Maternal soybean diet during lactation alters breast milk composition and programs the lipid profile in adult male rat offspring

PurposeTo evaluate the effects of maternal dietary soybean during lactation on the milk composition, body composition, lipid profile and glucose homeostasis of dams and offspring at weaning (21 days) and adulthood (150 days).MethodsLactating rats were divided into: casein control (C): casein diet; soy (S): soybean diet; soy oil control (SOC): casein diet, but with fat content similar to the S group.ResultsAt 21 days, S mothers showed lower estradiol, total cholesterol (TC), low-density lipoprotein cholesterol (LDL) and triglycerides (TG) in serum; and lower TC and TG in milk. The S offspring had lower body weight, body fat mass, TC, LDL, hyperleptinemia and hypertriglyceridemia. At 150 days, S offspring presented higher total mineral content and lower TC (v. SOC) and LDL (v. C and SOC), and hyperinsulinemia with lower glycemia v. SOC group, which had lower insulinemia with higher glycemia, TC and LDL.ConclusionsMaternal intake of soybeans in lactation changes the lipid content of breast milk and programmed offspring for phenotype of the lower metabolic risk, with lower serum TC and LDL, and seems to protect the progeny of alterations in glucose metabolism despite the higher lipid content. The difference in fat content of breast milk and the higher isoflavones content of soy diet are possible imprinting factors that could program the offspring.

Isotermas de sorção e caracterização físico-química de lácteos desidratados

The aim of this study was to determine the composition, establish the isotherms at 25 o C and apply the BET model for instant whole milk powder (LPI), instant skim milk powder (SMP), half skim milk powder (LPSD), pre-crystallized whole whey by primary nucleation (SPNP), pre-crystallized whole whey by adding 0.05% w / w of lactose (SP0, 05) and pre-crystallized whole whey by adding 0.1% w / w lactose (SP0,1). The Brunauer, Emmett and Teller (BET) model was utilized for analysis of the experimental data. Isotherms of the dried milk products evaluated were fitted to the BET model and the moisture contents were higher than those calculated for the monolayer. Water mass in the monolayer calculated by the BET model presented a statistically significant negative correlation (p=0.026) with the fat concentrations. The difference between enthalpy of adsorption in the monolayer and enthalpy of water condensation between water molecules in the monolayer and in the pure solvent presented statistically significant positive correlations with the concentrations of lactose (p=0.001) and negative correlations with moisture content (p=0.005).

COMPORTAMENTO DE PRODUTOS LÁCTEOS PROTÉICOS EM DIFERENTES CONDIÇÕES SIMULADAS DE PROCESSAMENTO TÉRMICO

Milk protein products (MPP) are routinely used by the industry, with the aim to provide improved texture, yield and palatability for processed food products. Understanding the behavior of the thermal protein denaturation for ingredients in the food matrix and its fundamental importance to the industry, this property may influence the attributes of the processed products. The objective of this study was evaluate the kinetics of the viscosity´s development from the rehydrated MPP in different concentrations, when used in different conditions of thermal processing using the Rapid Visco Analyzer (RVA) as a process simulator. Commercial samples of skimmed milk powder (SMP), whey protein concentrate (WPC), milk protein concentrate (MPC), whey powder (WP) and demineralized whey powder (DWP) were analyzed. The solid-liquid ratio evaluated were 0.1 g.g-1 a 0.4 g.g-1 for the WPC/MPC and 0.4 g.g-1 a 0.8 g.g-1 of dry solids per 1 g of water for SMP, WP and DWP because of the sensibility of the system to the concentration of solids. The Brazilian setup of industrial heat treatment used were 65oC/30min, 85o/15min and 95oC/5 min. Thus, the results could be interpreted as a function of the thickening rate during the heating and cooling. It was possible to optimize the different conditions of parameters of the MPP with the interpretations of the viscographic profiles obtained, with reference to the thermal behavior of proteins, especially for the WPC and MPC. Indeed, the RVA can be considered an emerging analytical tool for the study and knowledge of PDI, aiding to optimize the choice for the technological application in the food industry, through ongoing analysis of viscosity to estimate the rate of the protein denaturation.

QUALIDADE MICROBIOLÓGICA DE DOCES DE LEITE PASTOSOS

Doce de leite is a milk derivative that has high consumption in Brazil and South American countries. Due to the addition of sucrose and the high concentration of dairy solids, not only the rheological aspects of the product came to be admired by the South Americans, but also its economic and nutritional importance. The association the popular flavor to the nutritional benefits of milk and a longer shelf life, also provides the distribution of the product without the need for refrigeration. Although industrialized, Brazilian doce de leite is not standardized having many differences between brands and batches. In order to assess the incidence of bacterial and fungal contaminants in doce de leite, aliquots of three different batches of eight brands with SIF, produced in different states of Brazil and sold in Juiz de Fora (MG) were analyzed to assess the viability of microorganisms such as aerobic mesophils, coliforms at 30oC and 45oC, yeasts and molds, coagulase positive staphylococci, besides the research of Salmonella sp. and Listeria monocytogenes . Aerobic mesophils, molds, yeasts and coagulase negative staphylococci were recovered. The results showed that despite the creamy doce de leite having low water activity, it can allow microbial growth during storage.

CARACTERIZAÇÃO E AVALIAÇÃO MICROSCÓPICA DE LEITES CONDENSADOS PRODUZIDOS NO BRASIL

Brazilian condensed milk showed a favorable performance between the years 1996 and 2006, reaching over 50% exports of dairy products. Thus, it is important to raise awareness about the quality attributes of the national condensed milk. The objective of this study was to characterize and evaluate eight national commercial brands of condensed milk, with emphasis on microscopic evaluation of the presence of large lactose crystals, defect known as grittiness. Each brand was analyzed for the attributes size and number of lactose crystals, humidity content, lactose and sucrose, by performing three authentic replicates. The brand number eight showed the highest value for lactose mass cristalizable by unit product (33,6g.395g-1). There were significant differences between brands of condensed milk for the attributes size and number of lactose crystals. It was found a significant positive correlation between lactose content and number of lactose crystals (p<0,021). Microscopic analysis for condensed milk contributed to evaluate the quality of the product and microcrystalization process and through ease of use and relevance of the obtained information, it becomes an important tool available to industrys quality control. .