This study was conducted to evaluate the physicochemical and microbiological characteristics of raspberries exposed to different radiation doses. The fruits were harvested in the city of Campestre, MG, packed in polyethylene bags, and transported to the Federal University of Lavras (UFLA), where they were separated into 4 lots. Irradiation was performed at the Center for Development of Nuclear Technology in Belo Horizonte, MG. The doses used were 0 (control), 0.5, 1.0, and 2.0 kGy. After irradiation, the fruits were transported back to UFLA and stored at 1 ºC and 95% relative humidity (RH) for 12 days. The physicochemical analyses for mass loss, total soluble solids, titratable acidity, pH, total soluble sugars, total soluble pectin, firmness, vitamin C content, total antioxidant activity, and total phenolic, and the microbiological assays (coliform at 35 and 45 ºC, psychrotrophic and filamentous fungi and yeasts) were performed after 0, 3, 6, 9, and 12 days of storage. Lower loss of mass and filamentous fungi and yeast count were observed in the irradiated fruits, and 2 kGy was determined as the most effective dose for microbial control, but this irradiation dose also resulted in increased loss of fruit firmness.

Neste trabalho foram avaliadas as mudanças físico-químicas provocadas pelo tipo de armazenamento do suco de abacaxi 'Pérola', durante de 48 horas após sua elaboração. Foram avaliadas 4 condições de armazenamento, em ambiente refrigerado (4 ±1º C) e em temperatura ambiente (22 ±1º C), ambas com e sem luminosidade. O experimento foi conduzido em delineamento inteiramente casualizado, com os tratamentos dispostos em esquema fatorial 2 x 2 x 6, sendo 2 ambientes de luminosidade (presença e ausência), 2 condições de temperatura (refrigeração e ambiente) e 6 tempos de amostragem (0, 6, 12, 24, 36 e 48 horas) com 3 repetições. Foram analisados, pH, acidez titulável, sólidos solúveis, vitamina C total e cor utilizando-se as variáveis claridade (L*), ângulo de cor (hº) e cromaticidade (C*). O tempo de armazenamento apresentou influência negativa na qualidade do suco provocando a diminuição dos teores de ácido ascórbico e ácido cítrico, alterações na cor, principalmente o escurecimento. Entretanto, quando armazenado em ambiente refrigerado e sem luz, o suco conservou suas características iniciais por mais tempo, sendo estas melhor preservadas pelas baixas temperaturas.

In this work, psycho-chemical changes caused by the storage of homemade 'Pérola' pineapple juice, over 48 hours after its preparation were evaluated. Four storage conditions were evaluated in a refrigerated environment (4 ±1º C) and in room temperature (22 ±1º C) both in the presence and abscence of light. The experiment was conducted with a totally random design, with treatments arranged in a factorial 2 x 2 x 6, with 2 light conditions (presence and absence), 2 temperature conditions (cooling and room temperature) and 6 sampling times (0, 6, 12, 24, 36 and 48 hours) with three replicates. pH, titratable acidity, soluble solids, total vitamin C and color using the variables: luminosity (L*), hue angle (hº) and chromaticity (C*) were analyzed. The period of storage presented a negative influence on the pineapple juice, causing a reduction of ascorbic and citric acid contents and color changes, mainly darkening. However, when stored in refrigerated environment in the abscence of light, the juice conserved its initial features for a longer time, which were better preserved by low temperatures.