Ana Carolina Vilas Boas

Color, physicochemical parameters and antioxidant potential of whole grape juices subject to different UV-C radiation doses

Knowing that moderate stress such as UV radiation can activate defense mechanisms in plants, the use of UV-C radiation appears as hypothesis of a promising technique that would help to stimulate and enhance beneficial compounds for health, through a clean and healthy technology. In this study, the possible induction of secondary metabolism, the increase in the content of phytochemical compounds and physicochemical changes through the use of UV-C radiation were evaluated on whole grape juices produced with Vitis labrusca grapes, cultivar Isabel Precoce. Grapes were harvested, sanitized, exposed to UV-C radiation at doses of 0, 2, 4 and 6 KJ m-2, and then the juices were prepared and packed into amber glass bottles at room temperature. Analyses were performed at 0, 30, 60, 90 and 120 days of storage. Based on results obtained and conditions in which the experiment was performed, UV-C treatment in grapes caused abiotic stress in the fruits, affecting color, titratable acidity, soluble solids/titratable acidity ratio, vitamin C and percentage of protection against oxidation. Application of UV-C did not change levels of phenolic compounds in fruit juices or the percentage of scavenging free radicals, pH and soluble solids.

Antioxidant activity, anthocyanins and organic acids content of grape juices produced in Southwest of Minas Gerais, Brazil

O teor de compostos fenolicos e antocianinas em sucos de uva varia de acordo com a cultivar, maturidade e caracteristicas climaticas. Neste trabalho, objetivou-se a caracterizacao e a avaliacao da atividade antioxidante de sucos de uvas americanas produzidas no sudoeste de Minas Gerais. As uvas foram colhidas, sanitizadas, sendo as grainhas e demais partes dos cachos descartadas. Entao, os sucos das cultivares Bordo (Vitis labrusca), Isabel Precoce (Vitis labrusca), BRS Violeta (hibrida) e BRS Rubea (hibrida) foram produzidos em equipamento artesanal por extracao em vapor de agua, acondicionados em frascos de vidro e armazenados a 18oC±2oC por 120 dias. As seguintes analises foram realizadas ao longo do armazenamento: cor (L*), pH, solidos soluveis totais, acidez titulavel, , antocianinas, atividade antioxidante (DPPH e β-caroteno/acido linoleico), fenolicos totais, vitamina C e acidos orgânicos. Entre as cultivares avaliadas, sugere-se o consumo do suco de uva da cultivar BRS Violeta, pelos maiores valores de vitamina C, atividade antioxidante, fenolicos totais, antocianinas, alem de apresentar melhores caracteristicas fisico-quimicas quando comparada ao suco das demais cultivares.

CONSERVAÇÃO DE PERAS MINIMAMENTE PROCESSADAS SUBMETIDAS A TRATAMENTOS QUÍMICOS

O trabalho teve como objetivo testar a eficacia de tratamentos quimicos na manutencao da qualidade de peras ‘Williams’ minimamente processadas. Inicialmente, realizaram-se a lavagem, a sanitizacao e a retirada das sementes dos frutos. Em seguida, foram realizados cortes no formato de palitos, e os mesmos foram imersos nas solucoes, compondo os tratamentos: acido ascorbico a 2 % (controle); acido ascorbico a 2% + cloreto de calcio a 2%; acido ascorbico a 2% + acido citrico a 2%; acido citrico a 1%; cloridrato de L-cisteina a 1%. Os frutos foram acondicionados em bandejas de polipropileno, armazenados em câmara fria a 5oC por 12 dias e avaliados a cada tres dias. O tratamento com cloridrato de L-cisteina a 1% foi o mais eficaz na inibicao do escurecimento em peras minimamente processadas; no entanto, frutos tratados com acido ascorbico + cloreto de calcio apresentaram maior firmeza durante todo o periodo avaliado, alem de quantidades significativamente maiores de vitamina C quando comparado a formulacoes que nao continham acido ascorbico na composicao.

Cassava starch edible coating incorporated with propolis on bioactive compounds in strawberries

O morango e um fruto muito apreciado em todo o mundo por apresentar atributos de qualidade atrativos para o consumidor e destaca-se por seu alto conteudo de compostos fenolicos, contribuindo, positivamente, para propriedades biologicas de interesse nutricional. Objetivou-se, neste estudo, avaliar o efeito de combinacoes do revestimento de fecula de mandioca incorporado com propolis, sob o conteudo de fitoquimicos e na manutencao e incremento da atividade antioxidante de morangos. Os tratamentos utilizados foram fecula de mandioca 3% (CS), fecula de mandioca 3% + extrato etanolico de propolis 33% (CS + P33%), fecula de mandioca 3% + extrato etanolico de propolis 66% (CS+P66%) e controle (C), sendo os frutos armazenados a 4 oC ± 0,5 oC e UR90% por 16 dias, perfazendo um delineamento inteiramente casualizado com 4 tratamentos e 5 tempos de avaliacao. Avaliaram-se teores de vitamina C, compostos fenolicos totais, antocianinas e atividade antioxidante, por dois metodos. O revestimento com 66% de propolis promoveu maior conteudo de Vitamina C que os frutos submetidos a outros tratamentos aos 8 e 12 dias. Para a atividade antioxidante, frutos tratados com CS mantiveram maior %SRL (sequestro de radicais livres) em todos os tempos de avaliacao. Frutos controle apresentaram maior teor de antocianinas no ultimo tempo de avaliacao, quando a maior capacidade antioxidante pelo metodo ABTS (2,2´-azino-bis(3-etilbenzotiazolina-6-acido sulfonico)) foi observada em frutos com os tratamentos CS e CS + P66%. Observou-se uma tendencia ao aumento do teor de compostos fenolicos durante o armazenamento em todos os frutos avaliados. As concentracoes de propolis utilizadas, no entanto, nao foram suficientes para incrementar ou manter a capacidade antioxidante e o teor de fenolicos dos morangos.

ANTIOXIDANT ENZYME ACTIVITY AND FRESH-CUT ARRACACHA QUALITY

The arracacha is an alternative of fresh-cut product; however it can be easily degraded after the processing techniques. The objective of this work was to evaluate the useful life of fresh-cut arracacha submitted to two types of cuts and storage, as well as to evaluate the activity of antioxidant enzymes. The roots were selected, sanitized and submitted to two cut types: cubed and grated. Then they were evaluated at 3 times: 0, 3 and 7 days. The cutting in cubes provided higher quality and lower SOD, CAT and APX activity. However, the grated product presented higher PG activity and lower PPO activity. The microbiological safety and the nutritional value were maintained in both cuts during the whole storage period. The useful life, regarding the physicochemical, nutritional and microbiological aspects, can be established at 7 days under refrigeration for fresh-cut arracacha.

ANTIOXIDANT ACTIVITY DURING STORAGE OF APPLES SUBJECTED TO IRRADIATION

Nowadays, the number of studies about fruit conservation as well as the benefits of consumption of foods rich in antioxidant compounds was increased. This study aimed to quantify antioxidant compounds and their activity and to evaluate the physical and chemical changes during the post-harvest storage of Evas apple cultivars that were subjected to gamma irradiation at doses of 0; 0.5; 1.0 and 1.5 kGy. The antioxidant activity was measured by the 2.2-diphenyl-1-picrylhydrazyl (DPPH) and the β-carotene/linolenic acid methods. Levels of total phenolics, ascorbic acid, color, and soluble solids were evaluated. The results showed that, regardless of the irradiation dose, there was an increase in % SRL during post-harvest storage of Evas apples. Low irradiation doses were able to preserve the phenolic compounds, maintain the ascorbic acid levels and avoid an increase in the soluble solids content.

Use of chemical treatments for conservation of minimally processed ‘Gala’ apples

The objective of this study was to test the effectiveness of additives on keeping the quality of minimally processed ‘Gala’ apple. The minimum process consisted of washing, sanitising and removing the central part of the fruit. Then, sticks of apple were obtained and immersed in the following solutions: control (2% ascorbic acid), ascorbic acid 2% + calcium chloride 2%, sodium ascorbate 2%, citric acid 1% and L-cysteine hydrochloride 1%. They were stored in polypropylene trays with lid, stored in a cold chamber at 5°C for 12 days and assessed every three days. The following variables were evaluated: appearance, weight loss, soluble solids, titratable acidity, pH, total soluble sugars, antioxidant activity, phenolic compounds and search for total and fecal coliforms. All treatments were effective to maintain the quality of minimally processed apples until the sixth day of refrigerated storage.

1-MCP nos aspectos fisiológicos e na qualidade pós-colheita de maçãs Eva durante o armazenamento refrigerado

The objective of this study was to investigate the effect of specific doses of the compound 1-methylcyclopropene (1-MCP), after harvest, on the physiological and physicochemical quality of apples Eva during refrigerated storage. After applying thetreatment with different doses of 1-MCP (0, 10, 50, 100 and 500mg L-1), fruit were stored in cold 0.5°C (±0.5) for up to 135 days. The cold storage with the application of 1-MCP resulted in a lower production of ethylene in fruits treated with doses of 10, 50 and 100mg L-1. The control group lost 45% of its firmness, while the treated groups lost on average 27% of their firmness the parameter C fruit color identified with a more intense color to the 135 days of storage and Hue angle showed that when treated with doses of 10 and 50mg L-1, fruit showed more yellow, evidenced best action of 1-MCP at low concentrations. Fruit that have not undergone the treatments showed a higher ratio of soluble solids and acidity, thus demonstrating increased metabolic activity.