Abstract The effect of irradiation through UV-C on the content of phenolic compounds, antioxidant activity, color, and texture profile was evaluated in Bordô variety grapes. Grapes were subjected to stress by irradiation at time of 0.5, 1.0, 4.0, 10 and 30 min that correspond at doses of 0.1, 0.3, 1.0, 2.4, and 7.2 kJ m-2, respectively. The total phenolic and anthocyanins content, antioxidant activity, color and texture of the grapes were evaluated after storage at 22 ºC for 24 and 48 h. In general, samples irradiated did not show an increase in total phenolic content, anthocyanin compounds and antioxidant activity. Hue and Chroma values indicated that the color of grapes did not change when irradiated. Texture profile analysis suggested that UV-C treatment delayed grapes softening.

Resumo Foi estudada a desidratação osmótica do kiwi, utilizando soluções osmóticas de sacarose a 45, 55 e 65 °Brix. Durante o tempo de desidratação, houve diminuição da umidade livre, da atividade da água e ganho de soluto pelo fruto. Observou-se um período inicial de secagem, em que as taxas de perda de água foram maiores. A diminuição da atividade da água foi maior quando o produto esteve imerso na solução a 65 °Brix. O teor de umidade de equilíbrio estimado pelo modelo de Peleg diminuiu significativamente com o aumento da concentração da solução osmótica e os valores de difusividade de água estiveram na faixa entre 1,5 × 10-9 a 1,9 × 10-9 m2 s-1. As pressões osmóticas das soluções também foram preditas.

Abstract Osmotic dehydration of kiwi was evaluated using 45, 55 and 65 °Brix sucrose solutions. Free moisture, water activity and solutes gain decreased in fruit during the process. Water loss rates were higher in the beginning of drying. Water activity decrease was higher when the product was in 65 °Brix solution. The equilibrium moisture content estimated by the Peleg model decreased significantly with increasing concentration of the osmotic solution, and the diffusivity values of water loss were in the range from 1.5 × 10-9 to 1.9 × 10-9 m2 s-1. The osmotic pressures of the solutions were also predicted.

ABSTRACT This study aimed to evaluate the influence of the drying air temperature (140 and 160°C) and the concentration of encapsulating agents gum Arabic and polydextrose (10 and 15%) on the physicochemical characteristics of the red cabbage extract obtained through extraction in acidulated water and drying using a spray dryer. The anthocyanin retention, antioxidant activity, water activity, solubility, color and microstructure of the final product were analyzed. Results showed that increase in the temperature did not cause significant changes in the anthocyanin quantity and antioxidant activity. The microscopic analysis revealed that for both the encapsulating agents, the absence of fissures and porosity in the particle surfaces produced powder with high solubility in water. The principal component analyses showed a strong correlation between the anthocyanin content and the antioxidant activity (r = 0.82) and luminosity (r = 0.81).

The present work aimed to evaluate glycerol, maltodextrin, polydextrose and sorbitol for the osmotic dehydration of yacon for diabetics, keeping its properties as prebiotic. Osmotic dehydration was carried out using a yacon to 33% concentrated syrup weight ratio of 1:12, with magnetic stirring at 23ºC and atmospheric pressure. The best results were achieved for glycerol and sorbitol with 80 ± 4% and 81± 1% of water removal and increase of 3.73 ± 0.11 and 4.30 ± 0.16 times in total soluble solids respectively. Maltodextrin did not promote dehydration.

Fructooligosaccharides (FOS) are food ingredients applied due to combination of prebiotic benefits and interesting technological properties, being used as a sugar substitute. The knowledge of their physicochemical characteristics is important for predicting the stability of the food products where they are added. For this reason, a saccharides powder extracted from yacon (Smallanthus sonchifolius) roots by membrane technology and freeze-dried was investigated. Color, water activity (aw), microstructure by Scanning Electron Microscopy coupled to Energy- dispersive X-ray Spectroscopy (SEM-EDS) and crystallinity by X-ray diffraction were evaluated. The obtained product, containing 19.75% FOS, 36.66% glucose and 43.59% fructose (w/w) was a whitish granulated powder, with aw of 0.284 and CIELAB color coordinates L*, a* and b* of 76.25±1.19, -1.03±0.09 and 1.02±0.03, respectively. It was highly hygroscopic and with agglomeration tendency, confirmed by the formation of bridges between particles on the SEM images. No peaks were identified at X-ray diffractograms, indicating its amorphous characteristics, but sample high hygrospicity and formation of a rigid mass might have hampered a trustable X-ray analysis.

As propriedades funcionais tecnológicas do amido nativo e modificado (hidrólise ácida) de pinhão (Araucaria angustifólia) foram comparadas às propriedades do amido nativo e ácido hidrolisado de milho. As espécies de amido foram hidrolisadas (3.2 mol.L-1 HCl, 44 ºC, 6 horas) e avaliadas, antes e após a reação de hidrólise, de acordo com as análises de formação, fusão e termorreversão do gel, retrogradação (em um período de 30 dias, com medidas a cada 3 dias), estabilidade ao congelamento e descongelamento (após 6 ciclos de congelamento e descongelamento), poder de inchamento e índice de solubilidade. Os resultados obtidos demonstraram que o amido de pinhão apresenta menor tendência à retrogradação quando comparado ao amido de milho, tanto para a forma nativa quanto na modificada, após períodos similares de armazenamento. O amido nativo de pinhão (APN), quando submetido a sucessivos ciclos de congelamento e descongelamento, apresentou menor sinérese do que o amido de milho nativo (AMN). Nas temperaturas de 25, 50 e 70 ºC, a solubilidade do APN foi menor do que a obtida pelo AMN. Entretanto, para a forma modificada, o amido de pinhão apresentou maior solubilidade (p < 0,05) do que o amido de milho. Através dos resultados, pode-se afirmar que o tratamento ácido modificado realizado no amido de pinhão foi efetivo para a produção de um potencial substituto de gordura, propriedade que deve ser testada e analisada em estudos futuros.

Technological functional properties of native and acid-thinned pinhão (seeds of Araucária angustifolia, Brazilian pine) starches were evaluated and compared to those of native and acid-thinned corn starches. The starches were hydrolyzed (3.2 mol.L-1 HCl, 44 ºC, 6 hours) and evaluated before and after the hydrolysis reaction in terms of formation, melting point and thermo-reversibility of gel starches, retrogradation (in a 30-day period and measurements every three days), paste freezing and thawing stability (after six freezing and thawing cycles), swelling power, and solubility. The results of light transmittance (%) of pastes of native and acid-thinned pinhão starches was higher (lower tendency to retrogradation) than that obtained for corn starches after similar storage period. Native pinhão starch (NPS) presented lower syneresis than native corn starch (NCS) when submitted to freeze-thaw cycles. The acid hydrolysis increased the syneresis of the two native varieties under storage at 5 ºC and after freezing and thawing cycles. The solubility of NPS was lower than that of native corn starch at 25, 50, and 70 ºC. However, for the acid-thinned pinhão starch (APS), this property was significantly higher (p < 0.05) when compared to that of acid-thinned corn starch (ACS). From the results obtained, it can be said that the acid treatment was efficient in producing a potential fat substitute from pinhão starch variety, but this ability must be further investigated.

O efeito da embalagem em atmosferas modificadas sobre os insetos Sitophilus spp. nos grãos de milho orgânico foi estudado. Os grãos de milho foram empacotados em cinco atmosferas iniciais diferentes de 20% de O2, ou 20, 40, 60, 80% de CO2 com balanço de N2. As embalagens foram armazenadas por 30 dias a 26ºC. As concentrações de CO2 e O2 foram monitoradas dentro das embalagens durante o armazenamento. As análises de teor de umidade, acidez e pH foram também realizados no primeiro e trigésimo dia. Os resultados mostraram que no quinto, décimo quinto e trigésimo dia de estocagem não foram encontrados diferenças significativas nas porcentagens de insetos mortos quando CO2 foi usado. Os resultados relativos à progênie indicaram que no quinto dia o número de insetos emergentes foi menor a 20, 60 e 80% CO2. A completa inibição dos insetos foi atingida com 30 dias de exposição em atmosferas de CO2.

The effect of modified atmosphere packaging on the mortality of Sitophilus spp. in organic maize grain was studied. Maize grains were packed with five different atmospheres consisting of 20% O2, or 20, 40, 60, 80% CO2 with remaining N2. The packages were stored for 30 days at 26°C. CO2 and O2 concentrations were monitored inside the packages during the storage. The moisture content, titratable acidity and pH were analysed on the first and thirtieth day. At 5, 15 and 30 days of storage no significant differences were observed in the percentages of dead insects when CO2 was used. The results of progeny indicated that from the fifth day the number of emerging insects was low at 20, 60 and 80% CO2. Complete inhibition of the insects was achieved with 30 days of exposure in CO2 atmospheres.