Geraldo de Amaral Gravina

Desidratação por imersão-impregnação e secagem por convecção de goiaba

O objetivo deste trabalho foi avaliar as caracteristicas fisico-quimicas e sensoriais de goiabas in natura e submetidas a desidratacao por imersao-impregnacao e a secagem complementar por conveccao, alem de avaliar a estabilidade da cor das goiabas secadas apos 30, 60 e 90 dias de armazenamento sob refrigeracao. Amostras de goiaba foram imersas em solucoes de sacarose a 0,4 e 0,5 g mL-1, sacarose a 0,3 g mL-1 + sucralose a 0,2 g L-1, acucar invertido a 41% (p/p) e acucar invertido sem diluicao. Foram avaliados solidos soluveis totais, acidez titulavel, pH, cor, aroma, aparencia, sabor e textura. O teor de solidos soluveis totais das amostras aumentou linearmente em funcao do tempo de imersao, sem efeito significativo do tipo de acucar empregado no preparo da solucao. A preservacao do teor de acido citrico foi mais pronunciada em solucoes menos concentradas de sacarose. Amostras secadas nao submetidas a desidratacao osmotica exibiram maior alteracao de cor do que aquelas previamente desidratadas. Solucoes de sacarose sao mais eficazes na estabilidade da cor do que as de acucar invertido. As goiabas submetidas a desidratacao por imersao-impregnacao tiveram boa aceitacao sensorial, e aquelas secadas apenas por conveccao nao foram aceitas pelos provadores.

Multivariate analysis of combining ability for soybean resistance to Cercospora sojina Hara

Seven soybean cultivars (Bossier, Cristalina, Davis, Kent, Lincoln, Parana and Uberaba), with different levels of resistance to Cercospora sojina, race 04, were crossed according to a diallel design, with no reciprocals, to determine the general and the specific combining abilities for the resistance. The evaluations of the reaction to the disease were performed 20 days after the inoculation of the fungus on the most infected leaflet of the plant, in the parents and in the F1 hybrids. To quantify the resistance, the following characteristics were evaluated: infection degree (ID); number of lesions per leaflet (NLL); lesion mean diameter (LMD); lesioned leaf area (LLA); percentage of lesioned leaf area (PLLA); number of lesions per square centimeter (NLC) and disease index (DI). The relative importance of each characteristic was evaluated by the canonical variables analysis and the LLA and NLL characteristics were eliminated from the multivariate function. With the remaining five characteristics, a multivariate index was created using the first canonical vector, which was submitted to the diallel analysis, according to Griffings fixed model, method 2. The most important characters to discriminate resistant from susceptible soybean plants to C. sojina were: ID, LMD, NLC, DI and PLLA. Cristalina, Davis and Uberaba cultivars are the best ones among those tested that can be recommended as parents in soybean breeding programs seeking resistance to Cercospora sojina. The additive, dominant and epistatic genetic effects were important for the expression of the resistance, although the additive genetic effect was the most important component.

Parâmetros genéticos da resistência da soja a Cercospora sojina

The inheritance of soybean resistance to Cercospora sojina Hara was studied based on genetic parameters estimated by the analysis of means and variances of a multivariate index. The crosses between two resistant cultivars, Parana (P) and Uberaba (U), with a susceptible, Bossier (B), were used. The parents and F1, F2, BCR and BCS generations from each cross were evaluated on five characteristics associated to the disease: visually evaluated infection degree; lesion mean diameter; percentage of lesioned leaf area; number of lesions per square centimeter; and disease index. A multivariate index previously established was applied to the data of the generation analyses. The additive genetic effect was the most important in the determination of the characters related to the resistance of soybean to C. sojina. On both crosses (PxB and UxB) at least one kind of epistatic interaction (aa, ad and dd) was significant and the additive-dominant-epistatic model was more adequate to describe the resistance of soybean to C. sojina.

Qualidade nutricional de goiabas submetidas aos processos de desidratação por imersão-impregnação e secagem complementar por convecção

During dewatering and impregnation soaking (DIS), transfer of water and of natural compounds from the product to the hypertonic solution occurs, however, few studies have been carried out to identify and quantify the losses of these compounds. Thus, this work reports on the losses of vitamin C and of the following minerals: Na, K, Ca, Mg, Zn and Mn, in red guavas submitted to the combined process of DIS (at 50 oC for 2 hours) and convective drying (at 60 oC and air velocity of 1.25 m/s, to a final moisture content of 20% w.b.). Studies were carried out employing two types of solutes: sucrose (in 0.4 and 0.5 g.mL-1 solutions) and liquid invert sugar (in a 41% w/w solution and as an undiluted syrup). Also, a test was performed using a solution comprised of 0.3 g.mL-1 sucrose and 0.2 g.L-1 sucralose. The control treatment consisted of drying guava solely in the convective drier. The effect of storage conditions on the stability of ascorbic acid was assessed after 60 days at 7 and 25 oC. Results indicated reductions in the range of 20 to 64% in the amounts of the minerals studied at the end of the DIS process, as compared to the amount found in fresh fruits, and negligible losses of vitamin C, except in the treatment with undiluted liquid invert sugar. Convective drying promoted losses of vitamin C in the range of 32 to 68%. The ranges of vitamin C loss in storage at 7 and 25 oC were 58 to 82% and 70 to 86%, respectively.

Influência de biofilmes de fécula de mandioca e amido de milho na qualidade pós-colheita de mangas 'Tommy Atkins'

The objective of this work was to evaluate the effects of cassava starch and corn starch biofilm on the postharvest conservation of ‘Tommy Atkins’ mangos. The fruits were selected, washed, disinfected and coated with cassava starch and corn starch biofilm in the concentrations of 2%, 4% and 6%, and stored for 21 days at 12 ± 0.6oC and 86 RH, plus an additional period of 7 days at 21 ± 2oC and 67% RH. The effects of the treatments were evaluated by mass loss, maturation index, pulp firmness, total soluble solids content, titratable acidity and pH. The experiment was carried out in a completely randomized design in 7x4 factorial scheme (treatments x storage periods), with four replications. The results indicate that the use of cassava starch at 2% and corn starch biofilms at 4% reduced the mass loss, maintained the firmness, improved the visual aspects and prolong the storage period without decreasing the fruits quality.

Controle genético da resistência da soja à raça 4 de Cercospora sojina

The objective of this work was to study the genetic control of resistance to frogeye leaf spot in segregating populations derived from the cross between Parana and Bossier soybean cultivars. The progenitors and the F1, F2, RC1 and RC2 generations were evaluated for six plant characters associated to the disease: infection grade (NT); number of lesions per foliole (NLF); average diameter of lesion (DML); percentage of lesioned foliar area (PAFL); number of lesions per square centimeter (NLC) and disease index (ID). Soybean resistance to frogeye leaf spot behaved as a quantitative character, and the additive genic effect was the most important character. The influences on NT were the following: additive effect (62.05%), dominance effect (7.68%) and additive x additive, additive x dominant and dominant x dominant epistatic interactions (7.32%). The additive-dominant model was satisfactory to explain the variations only of PAFL and NLC characters. The influence of the effect of epistatic interactions varied from 2.22% for PAFL up to 30.78% for DML character. The additive-dominant genetic model is satisfactory to explain the behavior of the average of the generations of PAFL and NLC characters. However, for NT, NLF, DML and ID, the additive-dominant-epistatic model is more adequate.

Mecanismos de transferência de massa na desidratação osmótica de goiaba em soluções de sacarose, sucralose e açúcar invertido

The present work aimed at investigating the effect of sucrose, sucralose and inverted sugar solutions on the kinetics of osmotic dehydration of guava pieces. The fruits were cut in twelfths and immersed in sucrose solutions at 0.5 and 0.4 g mL-1; of sucrose at 0.3 g mL-1 + sucralose at 0.2 g L-1 and in inverted sugar syrup for 2 h at 50 oC, under agitation of 60 min. The undiluted inverted sugar solution promoted the highest levels of water loss and weight reduction in osmo-dehydrated guava pieces. The best overall performance was achieved by immersing guava pieces in sucrose solutions at 0.4 g mL-1 which led to water loss and mass reduction of similar values attained with sucrose solutions at 0.5 g mL-1; whereas maintaining the same level of solids gain achieved with sucrose solutions at 0.3 g mL-1.