Sérgio Henriques Saraiva

Revalidação do método titulométrico para determinação do ácido ascórbico

Validation of the method for determination of ascorbic acid in lemon by titration The present study aimed to revalidate the method for determination of ascorbic acid by titration to be applied in the laboratory of Food Chemistry Centre of Agricultural Sciences, Federal University of Espirito Santo. The revalidation process was carried out by evaluating parameters such as linearity , precision (repeatability), accuracy (recovery test) and detection limits, considering the acceptability criteria determined. The level of significance in hypothesis testing was 5%. Analyses included simple linear correlation coef ficient (r), coefficient of variation (CV) and regression analysis. The data were analyzed using the software Statistica 7.0. The quantitative method by titration of ascorbic acid was revalidated and evaluated in samples of ascorbic acid and lemon juice. It was found that the same complies with the limits established by regulatory agencies. The methods presented linear, repetitive and high recovery, with a maximum value of 98% and a minimum of 94.82% and a detection limit of 0.025 mg ml -1 in the lemon juice.

Crescimento vegetativo e produtividade de cafeeiros Conilon propagados por estacas em tubetes

The objective of this work was to evaluate the vegetative growth and productivity of conilon coffee-tree (Coffea canephora Pierre ex Froehner), proceeding from seedlings produced of deep-rooted cuttings initially in plastic tubes with capacity of 50 cm3. The treatments were constituted of permanence period in plastic tube for 0; 15; 30; 45 and 60 days. After these periods the plants were transplanted for polyethylene bags filled with substrate (soil + sand + manure bovine and chemical fertilization) maintained on the greenhouse with environment under shading canvas (50%) and automatic micro aspersion during 150 days. After this time the plants were maintained during 30 days in acclimatization greenhouse management. Field experiment was set up in September of 1999, at experimental area CCA-UFES, in Alegre, south state of the Espirito Santo, Brasil. The following measurements were made: length of orthotropic and plagiotropic branches after first year and the first four productions. The results showed there were no differences either in vegetative growth and fruits production.

Semisynthetic Phenol Derivatives Obtained from Natural Phenols: Antimicrobial Activity and Molecular Properties

Semisynthetic phenol derivatives were obtained from the natural phenols: thymol, carvacrol, eugenol, and guaiacol through catalytic oxychlorination, Williamson synthesis, and aromatic Claisen rearrangement. The compounds characterization was carried out by 1H NMR, 13C NMR, and mass spectrometry. The natural phenols and their semisynthetic derivatives were tested for their antimicrobial activity against the bacteria: Staphylococcus aureus, Escherichia coli, Listeria innocua, Pseudomonas aeruginosa, Salmonella enterica Typhimurium, Salmonella enterica ssp. enterica, and Bacillus cereus. Minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were determined using concentrations from 220 to 3.44 μg mL-1. Most of the tested compounds presented MIC values ≤220 μg mL-1 for all the bacteria used in the assays. The molecular properties of the compounds were computed with the PM6 method. Through principle components analysis, the natural phenols and their semisynthetic derivatives with higher antimicrobial potential were grouped.

Optimization of pectin extraction from Ubá mango peel through surface response methodology

A central composite design was used to determine effects of pH (1.16-2.84), extraction temperature (63-97°C) and time (35-85min) on the yield, degree of degree of esterification (DE) and viscosity of pectins extracted. For pectin extraction, the previously sanitized mango shells were dried and crushed to obtain the flour that was treated with an ethanol solution obtaining the alcohol insoluble residue (AIR). Subsequently, the AIR was mixed in ethanol with the extraction solution of hydrochloric acid. Pectin yields ranged from 18.8 to 32.1g/100g of AIR, whereas the degree of esterification (DE) and viscosity values ranged from 62.2 to 86.2% and from 1.58 to 45.85mPa·s, respectively. An inverse correlation was found between extraction yield and viscosity. Relying upon the desirability function, two optimum conditions were determined: 35min<t<48min; 85.4°C<T<97°C; 1.66<pH<2.4 and 80min<t<85min; 94.3°C<T<97°C; 1.66<pH<1.79. Under these conditions, yields >30% from the AIR, DE≥70.0% and η≥20.0mPa·s.

ÓLEOS ESSENCIAIS DE MANJERICÃO E GENGIBRE NA AROMATIZAÇÃO DE AZEITE DE OLIVA

O presente trabalho teve como objetivo aromatizar azeite de oliva com oleos essenciais de manjericao e gengibre e determinar a composicao quimica dos compostos presentes nos respectivos oleos. Os oleos essenciais de manjericao e gengibre foram obtidos por hidrodestilacao e analisados por cromatografia gasosa (CG) e por cromatografia gasosa acoplada a espectrometria de massas (CG-EM). Os azeites de oliva aromatizados foram submetidos a analise sensorial. Os componentes majoritarios determinados para o oleo essencial de manjericao foram o 1,8-cineol (33,63%) e linalol (35,29%). Os seis principais componentes volateis encontrados no oleo essencial de gengibre foram o citral, a mistura de geranial (18,79%) e neral (9,90%), -Amorfeno (10,38%), canfeno (9,98%), -felandreno (9,32%) e E,E-- farneseno (8,83%). Os resultados da analise sensorial revelaram boa aceitacao para os dois azeites formulados, indicando a existencia de um mercado a ser explorado.

OTIMIZAÇÃO DO PROCESSO DE SECAGEM EM LEITO DE ESPUMA DE EXTRATO DE CAFÉ

During the processing of soluble coffee occur losses of aromas, besides degradation and formation of undesirable compounds. Foam mat drying uses low temperatures, resulting in a high-quality product and occur less losses of volatile compounds and nutrients during the process. The objective of this work was to optimize the concentrations of emustab® and whey powder in the foam mat drying process of coffee extract, as well as to evaluate the effect of the temperature on drying kinetics. A Central Composite Rotatable Design (CCRD) was used, with the concentrations of the two agents ranging from 0 to 8%. Then, drying was performed at five temperatures (50, 55, 60, 65 and 70 ° C) and their kinetics were adjusted by comparing the Page, Henderson and Pabis and Exponential models by a non-linear

Cinética de secagem de acerola em leito de espuma e ajuste de modelos matemáticos

Acerola (Malpighia emarginata DC) is a fruit rich in nutrients, especially vitamin C, but the in natura fruit is highly perishable and hence processing of the acerola pulp becomes indispensable. The aim of this paper was to study the foam mat drying process of acerola pulp to evaluate the effect of temperature on the drying kinetics of the pulp and fit mathematical models in order to describe the operation. The experiment was carried out with three repetitions. The foam was prepared with 250 mL of the pulp plus 4% of foaming agent and spread evenly in stainless steel trays. The selected drying air temperatures were 50 °C, 55 °C, 60 °C, 65 °C and 70 °C. The moisture ratios were then calculated and the Page, Henderson and Pabis and Lewis mathematical models fitted for each temperature. The Page model showed the highest determination coefficient (> 0.99) and lowest standard error for the regression at all temperatures (<0.03). The proposed generalized model presented a determination coefficient of 0.9933. The Page model and the generalized model were adequate to describe the drying process of the acerola pulp. The moisture contents of the dehydrated products were in accordance with the values established by Brazilian law.

Características físico-químicas de bebidas de café tipo expresso preparadas a partir de blends de café arábica e conilon

In recent years, there has been a growing interest for exquisite beverages such as espresso coffee. Espresso coffee requires a high content of the aqueous extract to ensure a good body of the beverage, which can be obtained using coffee conilon. Espirito Santo State is the largest producer of conilon coffee in Brazil. Although there are several studies on the physico-chemical composition of Brazilian coffee, there is a lack of information about the use of conilon from Espirito Santo in the formulation of blends with Arabica coffee, as well as the physico-chemical characteristics of espresso coffee beverage obtained with these blends. The objective of this study was to carry out the physico-chemical characterization of espresso coffee beverage made ​​from blends of arabica and conilon coffees (in arabica and conilon proportions of 100:0; 80:20; 60:40; 40:20 and 0:100, respectively) with different types of processing (dry process and semi dry process) produced in Espirito Santo. The variables moisture, pH, titratable acidity and aqueous extract of the samples were analyzed. It was found that the use of conilon in blends with Arabica, in the two forms of processing, results in beverages with higher levels of pH, lower acidity and higher percentage of aqueous extract. A higher percentage of aqueous extract is interesting for the preparation of espresso coffee. The results demonstrate the feasibility of using conilon coffee in blends with Arabica coffee in brewing espresso coffee, when a higher aqueous extract beverage is desired.