Virgínia Martins da Matta

Microfiltration and reverse osmosis for clarification and concentration of acerola juice

Abstract The exotic tropical fruits are adequate for the increasing market of fruit juices and based fruit drinks by their diversity of aromas and flavours and by their nutritional value. In such group, acerola appears as potentially attractive due to its high ascorbic acid content. The objective of this work was to develop a process for obtaining clarified and concentrated acerola juice, maintaining its nutritional and sensory characteristics. The experimental procedure consisted of fruits pulping followed by an enzymatic hydrolysis, a clarification by microfiltration and the concentration by reverse osmosis. The obtained products presented the required microbiological counts and nutritional quality due to the ascorbic acid preservation. Vitamin C content of the integral juice was 1234 mg/100 g and in concentrated juice it reached 5229 mg/100 g. In an acceptability test most of the consumers (84%) liked the drink prepared with the clarified juice.

Chemical characterization and evaluation of antioxidant properties of Açaí fruits (Euterpe oleraceae Mart.) during ripening

Consumption of açaí fruits has been linked to positive health effects due to its phenolic content and nutritive value. The objective of this study was to characterize açaí fruits chemically and to determine the antioxidant capacity at three different maturity stages. With the exception of fat, amounts of macronutrients, minerals and titratable acids decreased during the ripening process. The same trend was observed for most of the phenolic constituents identified by HPLC-ESI-MS/MS. A consistent decline was shown for flavones and hydroxycinnamic acids. The concentration of the anthocyanins increased in the course of ripening. In accordance with the total amount of the identified phenolic compounds, the antioxidant capacity, measured by TEAC and TOSC, also decreased. However, the contribution of the main phenolic compounds to the overall antioxidant capacity evaluated by TOSC was estimated to be low.

Cold sterilization and clarification of pineapple juice by tangential microfiltration

Abstract Pineapple is a very appreciated tropical fruit due to its unique aroma and flavour. Pineapple juice was cold sterilised and clarified by crossflow microfiltration associated with an enzymatic treatment. A tubular polyethersulfone 0.3 μm pore size membrane with effective filtration area of 0.05 m2 was used in the pilot system. Ten experiments were carried out under the same operational conditions, 25°C and 100 kPa, in order to evaluate the cold sterilisation and clarification of pineapple juice by microfiltration. It was observed that the permeate flux did not change significantly after fifteen minutes of processing time. It was stabilised around 100 L/hm2. The clarification process was considered very efficient due to the great reduction of haze and viscosity, and by showing no significant changes in pH, acidity, sugar and soluble solid content of the juice. The permeate of the process was collected in sterile bottles inside a laminar flow station and kept under refrigeration (8°C) for a period of 28 d. The samples were submitted to microbiological evaluations in intervals of seven days. The microbiological analysis of the microfiltered pineapple juice showed that it was in agreement with the requirements by the Brazilian Legislation for juices and drinks.

Cashew apple juice stabilization by microfiltration

Abstract Cashew apple is a tropical fruit that presents high vitamin C content, rich flavour and aroma. Brazilian market of cashew apple juice is about 40,000 ton/y and it presents a low consumption at the international market. This work had the objective of studying the shelf-life stability of cashew apple juice clarified by microfiltration associated with enzymes, supposedly to present a lower astringency and a better physical stability. Cashew apple pulp was used as raw material. It was first hydrolysed and then microfiltered in a 0.3-μm pore size tubular membrane. Permeate juice was collected in a sterilised closed system and stored at room (30°C) and refrigeration (4°C) temperatures for 2 months. Ascorbic acid and tannin contents, haze, pH, acidity, soluble solids of the juice as well as microbiological counting were determined each 15 d. Juice storage at the lower temperature was appropriate for consumption after a 2-month shelf life, still as a vitamin C source and without any haze.

Desenvolvimento de um método de análise de vitamina C em alimentos por cromatografa líquida de alta eficiência e exclusão iônica

Vitamin C is an essential nutrient for human physiology. In Brazil, vitamin C supplements are expensive and most of the population obtains vitamin C through its consumption of fruits and vegetables. Therefore, the vitamin C assay in food is crucial in post-harvest studies to conserve and minimize losses of this highly sensitive nutrient. This study proposes a method for analyzing vitamin C by High Performance Liquid Chromatography using a hydrogen type ion exchange column, and demonstrates that it is more efficient than the traditional methods of reverse phase column (C18) for complex matrixes and low levels of this analyte. Chromatograms were baseline resolved and peak purity evaluation showed spectral homogeneity by photo diode array detector. This method was also tested using the best extraction solution to stabilize vitamin C, demonstrating that 0.05 M of superpure sulfuric acid (also the mobile phase) was the most efficient solution for this purpose.

Clarificação e concentração de suco de caju por processos com membranas

Os processos de separacao por membranas tem sido estudados como alternativa aos processos termicos de conservacao de alimentos, por serem conduzidos em condicoes amenas de temperatura, permitindo, assim, a preservacao de compostos termosensiveis como as vitaminas, por exemplo. O objetivo deste trabalho foi avaliar a utilizacao da microfiltracao e da osmose inversa para a obtencao de suco de caju clarificado e concentrado. O processamento consistiu de tres etapas principais: o tratamento enzimatico do suco integral; a microfiltracao para obtencao do suco clarificado; e a concentracao do suco clarificado por osmose inversa. Para o tratamento enzimatico, utilizou-se um complexo pectinolitico durante 1 hora. A clarificacao foi conduzida em uma unidade de microfiltracao tubular e, em seguida, foi utilizado um sistema de osmose inversa, do tipo quadro e placas, para concentrar o suco clarificado. Os fluxos medios de permeado obtidos foram de 184,0 e 11,3L/hm2 para a microfiltracao e a osmose inversa, respectivamente. Os taninos, responsaveis pela adstringencia do suco, foram retidos pela membrana de microfiltracao e, por isso, nao foram detectados nos sucos clarificado e concentrado. O suco clarificado contendo 12,1° Brix foi concentrado ate 28,6° Brix. A vitamina C aumentou de 162mg/100g no suco clarificado para 372mg/100g, no concentrado.

Suco de maracujá orgânico processado por microfiltração

The objective of this work was to evaluate the use of microfiltration to obtain clarified organic passion fruit juice and analyse its sensory acceptability. Passion fruit was cultivated under organic system in Rio de Janeiro State. The juice was submitted to an enzymatic treatment before microfiltration, in order to decrease its viscosity and pulp content, and to improve permeate flux. Microfiltration had been accomplished with a tubular 0.3 µm pore size membrane with 0.05 m2 of filtration area. The process promoted complete removal of the suspended pulp in permeated juice, which resulted in a limpid and clarified juice. Concerning the sensorial analysis, passion fruit refreshment obtained from clarified juice was approved by 75% of the consumers. The microfiltered passion fruit juice was conserved in plastic package for 28 days under refrigeration temperature (7oC). Results confirm the efficiency of microfiltration as an alternative method for conservation of passion fruit juice, and point out the importance of this technology for the processing of organic juices.

Produção e caracterização físico-química de fermentado de umbu

The objective of this study was to develop a fermented umbu drink aiming at adding value to this fruit and contribute for improving the families income in Brazil northeast semiarid region. The pulp used in the experiments was subjected to physico-chemical and microbiological analysis. For the production of liquor, the pulp was diluted with water, and needed a sugaring with sucrose up to 20.5°Brix. A commercial Saccharomyces cerevisiae wine yeast was used. The fermentation was conducted at 18°C for 18 days and subsequently underwent a drink with the aid of stabilizing agents of sedimentation, gelatin and bentonite, for 14 days at 1°C. After stabilizing the fermented umbu drink was subjected to filtered in filter press. The fermented alcoholic umbu drink showed an alcohol contents of 11.20°GL. The drink was analyzed for their physicochemical characteristics and all parameters were in accordance with current legislation.

Recuperação e concentração de componentes do aroma de caju (Anacardium occidentale L.) por pervaporação

Pervaporation is a membrane separation process in which components from liquid mixtures are fractionated due to their partial vaporisation through a dense selective membrane. This process can be used to recover aroma compounds. The objective of this work was to evaluate the pervaporation to obtain a natural aroma extract from cashew apple fruit, which can be used as an additive in the food industry. Cashew pulp was used as raw material. Pervaporation was carried out at 25 and 35 °C using polymethylsiloxane membranes. Samples of the cashew juice in the beginning and at the end of the pervaporation and from the permeate were picked to characterise the aromatic profile by GC-MS. The pervaporation of the cashew juice presented a high permeate flux, 0.11 kgh-1m-2 and 0.17 kg.hm-2, at 25 and 35 °C, respectively. The chromatograms showed an increase in the number of compounds in the permeate samples when compared to the chromatograms of the cashew juice. By comparing the peak areas, it could be observed that almost 50% of the identified components in the permeate samples presented an increase in the peak area, showing the potentiality of this process to the concentration of the aroma of cashew apple juice.

Conservação de água de coco verde por filtração com membrana

The green coconut water is sterile inside the nut, but during its extraction and bottling microbiological contamination and biochemical alterations can occur, resulting in quality loss and decrease of its commercial value. The present work aimed at studying the conservation of the green coconut water by microfiltration and ultrafiltration. For microfiltration, a 0.1µm pore size membrane was tested and for the ultrafiltration 100, 50 and 20kDa molecular weight cut off membranes were evaluated. The process efficiency was evaluated by the permeate flux and microbiological, physical-chemical, biochemistry and sensory evaluations. It was not observed significant variation in the physical-chemical parameters. The permeate water presented higher luminosity and lower haze than the original coconut water. The protein content of the permeate coconut water, which is an indirect measure of enzyme concentration, was proportional to membrane porosity. The shelf-life evaluation revealed satisfactory results in relation to the microbiological quality. Among consumers who tasted the ultrafiltrated coconut water, 94% liked the product.