Hilary Castle de Menezes

Optimization of the roasting of robusta coffee (C. canephora conillon) using acceptability tests and RSM

Abstract With the objective of optimizing the roasting of robusta coffee (Coffea canephora Conillon), a two factor central composite design (11 samples) was used to optimise the settings for roasting time and the initial internal temperature of the roaster drum on response variables of acceptance with 25 consuming assessors, for the sensory attributes of beverage aroma, flavour and colour. Predictive models were also obtained for the instumental measurement of the colour of the beans and ground coffee. The optimum range for roasting was shown to be a time of 22–28 min at a temperature of 225–230°C, corresponding to the degree of roasting characterized by the following range of colour of roasted robusta beans: L* between 37.05 and 40.69, a* between 2.29 and 4.15 and b* between 2.70 and 6.29.

Incidence of toxigenic fungi and ochratoxin A in dried fruits sold in Brazil

A total of 117 dried fruit samples (black sultanas, white sultanas, dates, dried plums, dried figs and apricots) from different origins were analysed both for toxigenic fungi and for the presence of ochratoxin A. Amongst the fungi found, Aspergillus niger was predominant, with 406 isolates, of which 15% were ochratoxin A producers. They were followed by A. ochraceus, with 15 isolates and 87% ochratoxigenics, and A. carbonarius, with only five isolates of which 60% were ochratoxin A producers. The average infection rates for A. niger in black sultanas, plums, figs, dates and white sultanas were 22.0, 8.0, 4.0, 1.5 and 0.5%, respectively. The apricot samples were not contaminated by any fungi or ochratoxin A. Black sultana and dried figs contained the highest contamination with ochratoxin A, with 33 and 26.3% of the samples containing more than 5 µg kg−1 respectively, while all the white sultanas, dates and plums had no sample that exceeded this limit.

Processamentos de amêndoa e torta de castanha-do-Brasil e farinha de mandioca: parâmetros de qualidade

Brazil nut (Bertholletia excelsa H.B.K.) and cassava (Manihot esculenta Crantz) are important raw materials, which constitute the basis of subsistence for those who live in the Amazon region. Due to a total lack of incentive for their use by the national food industry, this study aimed at processing Brazil nuts to obtain the nuts and the meal and at processing cassava to obtain the flour, studying the quality parameters which could justify and encourage their use. The absence of aflatoxin in both the nuts and meal indicated the high quality of the Brazil nuts with respect to food safety. The presence of a selenium content of 2.04mg/Kg in the nut and 7.13mg/Kg in the meal, a food fiber content of 8.02% in the nut, 15.72% in the meal and 5.68% in the flour, a protein content of 40.23% in the meal and carbohydrate content of 79.33% in the flour allowed for the characterization of products based on the nut as high protein, rich in selenium and fiber and of the cassava as rich in carbohydrate and fiber. The protein of the nut is complete and rich in sulfur amino acids and contains all the essential amino acids, some with values greater than and others equal to, the FAO standards. Due to these contents of amino acids, selenium and fiber, the consumption of the Brazil nut and derivatives should be encouraged due to their relevant functions with respect to human health.

Effect of processing and roasting on the antioxidant activity of coffee brews

The aim of this work was to evaluate the effect of processing and roasting on the antioxidant activity of coffee brews. Brews prepared with light, medium and dark roasted coffees were analyzed. The pH, total solids content, polyphenols content, reducing substances and chlorogenic acids content were determined. The antioxidant activity of aqueous extracts, the guaicol decolorizing and the capacity to inhibit lipid peroxidation were also analyzed. The antioxidant activity of coffee brews were concentration-dependent. A progressive antioxidant activity and polyphenols content was observed decreasing with roasting. The light roasted coffee showed the highest antioxidant activity and dark roasted coffee showed the lowest antioxidant activity. The results indicate that the ingestion of coffee brews prepared with light and medium roasted coffees might protect cells from oxidative stress damages.

Estabilidade da polpa de pitanga sob congelamento

Amongst tropical fruits, the pitanga (Eugenia uniflora L.), still little studied, shows great sensory appeal and excellent vitamin quality, due to its high carotenoid level. The objective of this study was to evaluate the stability of pitanga pulp during frozen storage (-18°C) with respect to the following parameters: pH, total titratable acidity, soluble and total solids, total and reducing sugars and sensory acceptance determined after 0, 30, 60 and 90 days, and total carotenoid contents and instrumental colour measured after 0, 15, 30, 45, 60 and 90 days. The reaction kinetics for the degradation of the colour parameter a* adjusted better to a 1 order kinetic model (R2 =91.69%), whereas the total difference in colour (DE*) adjusted better to a zero order kinetic model (R2 =91.91%). In the sensory analysis, the attribute of appearance varied significantly (p<0.05) after 90 days of frozen storage. Thus there was a marked fall in sensory acceptance and in the positive attitude towards buying of the nectar formulated with pitanga pulp stored for 90 days at -18°C.

Extrusão de misturas de castanha do Brasil com mandioca

Considering that Brazil nut presents high nutritional potential, low consumption in Brazil, low added-value and is an organic product; that cassava has high productivity and low cost; and that the technology of thermoplastic extrusion presents wide applicability and considerable advantages, the objective of this work was to use these three variables, formulating Brazil nut and cassava flour mixtures and processing them by extrusion, with the aim of obtaining ready-to-eat extruded products containing high levels of vegetable protein. Semi-defatted Brazil nut cake and cassava flour were used to formulate the mixtures for extrusion. A complete factorial central composite design (23) with 3 independent variables, and the response surface methodology were used to evaluate the results of the proximate composition and caloric value, according to the variations in the quantity of nut, moisture content and temperature. The results indicate that the mixtures with higher Brazil nut levels present higher levels of protein, fat and ash, while the mixtures with less Brazil nut present higher levels of carbohydrate. The average regression coefficients of the statistical model for the responses are: moisture 7.40; carbohydrate 51.09; protein 15.34; fat 11.77; total fibre 9.92 and kcal 371.65. The trials with lower quantities of Brazil nut and higher quantities of flour are more expanded and of a lighter colour, while those with more Brazil nut do not expand and are greyish in colour. It is concluded that the addition of Brazil nut to cassava flour results in a mixture that could be submitted to extrusion, producing an extruded product that could serve as a ready-to-eat source of vegetable protein, and attend the demands of consumers who do not consume proteins of animal origin.

Estabilidade sensorial de suco de maracujá pronto para beber acondicionado em latas de aço

The purpose of this work was to evaluate the preservation of the sensorial and physicochemical characteristics of ready-to-drink passion fruit juice packaged in three-piece welded tinplate cans with different internal coatings of the body and side strips, based on a storage test. The product evaluated was ready-to-drink passion fruit juice packaged in cans with an internal layer of 2.0 g.m-2 of tin, with three inner organic coating systems, stored at 25 and 35 °C for 360 days. A sharp decrease in ascorbic acid content was recorded up to day 180, after which it remained constant until the end of the storage period at the two aforementioned temperatures and in all the types of cans studied. The color evaluation showed the juice browning before 120 days of storage, and subsequent discoloration between 300 and 360 days, at the two storage temperatures. The sensorial analysis during storage indicated a similar performance for all the cans, which was lower only in the case of one packaging variable. The main changes recorded during the storage period were associated with inherent modifications of the beverage itself and not to juice/packaging interaction. This study led to the conclusion that all the types of packaging under study are suitable for ready-to-drink passion fruit juice for a minimum shelf-life of 12 months.

Identificação e quantificação de voláteis de café através de cromatografia gasosa de alta resolução / espectrometria de massas empregando um amostrador automático de "headspace"

Employing an automatic headspace sampler, the headspaces of three commercial brands of ground roasted coffee were qualitatively and quantitatively analyzed by gas chromatography / mass spectrometry. Since the methodology did not involve aroma isolation or concentration, their natural proportions were maintained, providing a more accurate composition of the flavors, and simplifying sample preparation. The automatic sampler allowed good resolution of the chromatographic peaks without cryofocusing the samples at the head of the column during injection, reducing analysis time. Ninety one compounds were identified and some known coffee volatiles, such as dimethyl sulphide, methional and furfuryl mercaptan were not detected. The more concentrated volatiles could be identified using two internal standards. The technique proved viable, for both characterization and for quantification of coffee volatiles.

Microstructure and adsorption characteristics of mango chips obtained by osmotic dehydration and deep fat frying

The aim of this work was to evaluate the effects of combined osmotic dehydration and deep fat frying on mango tissue and to determine sorption isotherms for the final products. Fresh, osmotic dehydrated (OD), and OD-fried (chips) slices of Palmer and Tommy Atkins cultivars were examined by scanning electron microscopy. Sorption isotherms of mango chips were obtained using dynamic vapor sorption. Micrographs suggested that osmotic treatment had no effect on tissue structure, while chips showed a shrunk cellular matrix and plasmolyzed cells, with oil globules adhered to the surface. Isotherms of mango chips had type-III characteristics for both cultivars.

Otimização do processo de extrusão termoplástica da mistura castanha do Brasil com farinha de mandioca

The objective of this work was to optimize the conditions of processing mixtures of Brazil nut with cassava flour through thermoplastic extrusion as a function of acceptability. A 23 full factorial design was used for the production of the extrudates and the evaluation of the products was according to acceptability responses. An affective hedonic scale of 9 points was applied to evaluate global acceptability and a 5-point scale was used to evaluate purchase intention. The results of the response surface methodology indicated that increases in Brazil nut percentage, temperature and moisture increased global acceptability and purchase intention of the product, with an optimized processing region in the following conditions: temperature between 120 and 160 °C, Brazil nut percentage between 48 and 80% and moisture between 20 and 25%. If Brazil nut percentage, temperature and moisture of the mixture were too high or too low, global acceptability and purchase intention decreased. The highest acceptance and purchase intention in this study were found for the central points and indicate the validity of the model.