Angela Kwiatkowski

CARACTERISTICAS DO MILHO DOCE (Zea mays L.) PARA INDUSTRIALIZAÇÃO

No Brasil o milho doce e uma hortalica voltada para o processamento industrial, sendo ainda pouco difundido para o consumo “ in natura” pelo restrito numero de cultivares adaptadas ao clima tropical. A principal diferenca entre o milho doce e o milho convencional e a presenca de alelos mutantes que bloqueiam a conversao de acucares em amido, no endosperma, conferindo o carater doce, tornando o milho doce enrugado e translucido quando seco. As caracteristicas exigidas pelo mercado consumidor de milho doce diferenciam-se das do milho verde comum. A industria tem preferencia por cultivares que possui maior teor de acucar e menor teor de amido, alem de maturacao, tamanho e formato de espigas uniforme. A textura e a espessura do pericarpo do grao tambem sao fatores de qualidade do milho verde. Esses fatores estao diretamente associados a aceitacao do produto pelos consumidores. Visando estas definicoes este trabalho tem como objetivos apresentar as caracteristicas do milho doce para industrializacao.

Polyphenoloxidase and peroxidase in avocado pulp (Persea americana Mill.)

The aim of the present investigation was to evaluate the enzymatic activity of polyphenoloxidase and peroxidase in avocado pulps, from the Northwest area of Parana-Brazil, in order to compare the varieties on their enzymatic activity for both, minimum and industrial processing. Enzymatic extracts were prepared from avocado pulp of Choquete, Fortuna and Quintal varieties, in green and ripe maturation stage. Thermal treatment was applied with temperatures 60, 65, 70, 75 and 80 °C. The enzymatic activities were determined by using spectrophotometer. A decline of polyphenoloxidase activity was observed in all of the varieties when both, temperature and time increased. Total inactivation of enzymes was not observed in the largest temperature. Fortuna and Choquete variety showed the lowest polyphenoloxidase activity in the ripe stage. Soluble peroxidase showed activity in the green stage, whereas, ionically bound peroxidase activity increased with the change from green to ripe maturation stage in Choquete variety.

Extraction and stability of anthocyanins from the benitaka grape cultivar (Vitis vinifera L.).

Summary Anthocyanins are little used in foods and beverages, since they show low stability to the processing and storage conditions when compared to artificial dyes. The aim of the present study was to evaluate the extraction processes and the influence of caffeic acid on the stability of anthocyanins extracted from the Benitaka grape cultivar (Vitis vinifera L.). The grapes were obtained from the town of Marialva in the Northwest area of the State of Parana, Brazil, cultivated using a conventional production system, that is, a system using traditional cultivation techniques and phytosanitary control measures. Different concentrations of the solvents methanol and ethanol and different pH values were used to extract the anthocyanins. The stability of the pigments was evaluated with the addition of caffeic acid in the presence and absence of light. Ethanol, at 70% and pH 2.0, was the most efficient system in the extraction of anthocyanins from the grape samples. The stability of the anthocyanins was affected by the presence of light, and the greater the proportion of caffeic acid, the greater the half-life of this pigment, both in the presence and absence of light, showing a reduced degradation speed.

Post-harvest conservation of organic strawberries coated with cassava starch and chitosan

The strawberry is as non-climacteric fruit, but has a high post-harvest respiration rate, which leads to a rapid deterioration at room temperature. This study aimed to evaluate the application of biodegradable coating on postharvest conservation of organic strawberries, cv. Camarosa, packed in plastic hinged boxes and stored at 10oC. The treatments consisted of: a) control; b) 2% cassava starch; c) 1% chitosan; and d) 2% cassava starch + 1% chitosan. Physical and chemical characteristics of fruits were evaluated at 3, 6 and 9 days of storage, and microbiological and sensory analyses were carried out at the end of the storage period. The treatments influenced positively the post-harvest quality of organic strawberries. The coating cassava starch + chitosan provided the best results, with less than 6% of loss in fruit mass, lower counts of yeast and psychrophilic microorganisms and the best appearance according to the sensory analysis.

Biodegradable coatings on the postharvest of blackberry stored under refrigeration

Blackberry is a notable fruit due to bioactive compounds. However it has a fragile structure, which reduces the consumption in natura. The aim of this study was to evaluate the physical and chemical quality of the cv. Tupy blackberry fruits, produced in an organic system, and coated with emulsions based on cassava starch and water kefir grains stored under refrigeration. The fruits were divided into three groups: a control (T1) and two treatments with coatings. The coatings used were: cassava starch solution 2.5% (T2); water kefir grains at 20% (T3). The fruits of the three treatments were stored at 10 ± 2 oC and RH 85 ± 3%, and were evaluated every three days for 12 days period. It was determined: weight loss, firmness, pH, titratable acid, soluble solids, ratio, anthocyanins and decay incidence. The results for the chemical features showed statistical differences (p>0.05) except for the pH value at the end of the storage. There were differences between crop for all parameters. During the storage period, the anthocyanin content increased on the 2008 crop and reduced on the fruits of 2009. To reduce the decay incidence it is recommended to use the coating with kefir grains. These fruits can be consumed until the third day of storage at 10 oC.

Physicochemical and microbiological characterization of cassava flower honey samples produced by africanized honeybees

Cassava producers in the region of Marilia-Sao Paulo are integrating their farming activity with beekeeping to diversify their income. The aim of this study was to evaluate the physicochemical and microbiological quality of honey samples produced by Africanized honeybees Apis mellifera from cassava flower in 2008. Analysis were carried out for pH, total soluble solids (TSS), acidity, moisture, reducing and total sugars, apparent sucrose, hydroxymethylfurfural, color, ash, proteins, water insoluble solids, diastasic activity, mineral content, microbiological evaluations, and mineral and hydrocyanic acid (HCN) content. The honey samples showed physicochemical and microbiological characteristics favorable to commercialization, with the exception of apparent sucrose and acidity, which show the need for a narrow focus of attention to the honey maturation degree at the harvest time and more careful monitoring during production and processing. The commercialization of Brazilian cassava honey, still little explored, can be widely spread in the market since the levels of hydrocyanic acid (HCN) showed no consumption risk; in addition the simultaneous production of honey and cassava provides an alternative to family income increase.

AVALIAÇÃO DE CAROTENÓIDES EM CENOURA E ANÁLISE SENSORIAL DE BARRAS DE CEREAIS ELABORADAS COM CENOURA DESIDRATADA

As barras de cereais estao ganhando cada vez mais espaco no mercado de alimentos praticos e saudaveis. Elas fornecem nutrientes essenciais para o organismo como carboidratos, com destaque para as fibras, alem de proteinas, vitaminas e minerais. A cenoura e um alimento amplamente utilizado em dietas por conter baixo teor calorico e ser uma das principais fontes de β-caroteno (pro-vitamina A). Este trabalho teve como objetivo o desenvolvimento de barras de cereais elaboradas com cenouras desidratadas em diferentes quantidades e granulometrias. Foram realizadas analises de carotenoides totais e aceitabilidade sensorial. Apos o branqueamento, a cenoura apresentou reducao de 39,5% do teor de carotenoides e maior teor apos a desidratacao. Na analise sensorial foi observada maior aceitabilidade da formulacao contendo farinha de cenoura desidratada em todos os atributos avaliados, alem de apresentar maior intencao de consumo pelos provadores. As barras de cereais com cenoura desidratada podem ser introduzidas no mercado como alternativa para aumentar a ingestao de carotenoides na dieta.