RESUMEN
Cryopreservation of the germplasm for long-term periods is of great importance to maintain the genetic resource. Argentina is one of the world's highest lemon producing country. The performance of different cooling/warming rates in the cryopreservation method of Citrus limon L. Burm cv. Eureka seeds and their influence on the interval of optimal moisture content in the desiccation stage were analyzed. Water sorption isotherm was determined and modeled using D'Arcy & Watt equation; it provided important information concerning the amounts of water associated to strong, weak and multimolecular binding sites along the sorption isotherm. Seeds tolerated a wide range of desiccation conditions (0.1Asunto(s)
Citrus/crecimiento & desarrollo
, Criopreservación/métodos
, Desecación/métodos
, Germinación/fisiología
, Semillas/fisiología
, Argentina
, Rastreo Diferencial de Calorimetría
, Lípidos/análisis
, Transición de Fase
, Agua/química
RESUMEN
The use of high hydrostatic pressure (HHP) on fresh beef causes a deleterious effect on red colour. A beef product subjected to HHP exhibiting acceptable colour and microbiological stability was developed; the process requires as a first step the immersion in a preservative solution containing ascorbic acid, sodium nitrite, and sodium chloride. Desirability functions were used to optimise the composition of this solution in order to maintain the colour attributes minimising the concentration of sodium nitrite. The product was packed in low gas permeability film before HHP treatment. The effect of the applied pressure (300, 600 MPa) on quality parameters (colour,texture) was analysed. The stability of the product during storage at 4 °C was determined by microbial counts, colour, texture, and exudate. The combination of treatments provided acceptable colour and microbiological stability during four and six weeks of refrigerated storage after the product has been subjected to 300 and 600 MPa, respectively.
Asunto(s)
Ácido Ascórbico , Manipulación de Alimentos/métodos , Conservantes de Alimentos , Productos de la Carne/análisis , Presión , Cloruro de Sodio , Nitrito de Sodio , Animales , Bovinos , Recuento de Colonia Microbiana , Color , Microbiología de Alimentos , Conservación de Alimentos/métodos , Almacenamiento de Alimentos/métodos , Humanos , Presión Hidrostática , Productos de la Carne/microbiología , Productos de la Carne/normas , TemperaturaRESUMEN
BACKGROUND: Three categories of seed storage behavior are generally recognized among plant species: orthodox, intermediate and recalcitrant. Intermediate seeds cannot be stored in liquid nitrogen (LN) without a previous partial dehydration process. The water content (WC) of the seeds at the moment of immersion in LN must be regarded as the most critical factor in cryopreservation. The purpose of this study was to investigate the basis of the optimal hydration status for cryopreservation of Citrus seeds: C. sinensis (sweet orange), C. paradisi (grapefruit), C. reticulata (mandarin) in LN. RESULTS: To study the tolerance to dehydration and LN exposure, seeds were desiccated by equilibration at relative humidities between 11 and 95%. Sorption isotherms were determined and modeled; lipid content of the seeds was measured. Seed desiccation sensitivity was quantified by the quantal response model. Differential scanning calorimetry (DSC) thermograms were determined on cotyledon tissue at different moisture contents to measure ice melting enthalpies and unfrozen WC. Samples of total seed lipid extract were also analyzed by DSC to identify lipid transitions in the thermograms. CONCLUSIONS: The limit of hydration for LN Citrus seeds treatment corresponded to the unfrozen WC in the tissue, confirming that seed survival strictly depended on avoidance of intracellular ice formation.