La energía nuclear en la mejora y conservación de algunas plantas de interés alimenticio

Abstract

[EN] Results obtained for different investigators on irradiation of various plants are discussed in this papel. Also our own experimental research is introduced. In recent years a number of authors have observed that ionizing radiation used to inhibit sprouting or to radio-pasteurize of fresh fruit and vegetables, affect sorne of these products in such a way that they suffer sorne different changes with inc_reasing doses. With certain doses the irradiated products become progressively soft. The increasing soitening has been attributed to sorne chemical changes, mainly to a decomposition of pectic substances present in the cell wall. Otherwise, doses inhibiting sprouting affect the wound healing mechamism to such an extent, that this may be considered one of the most important causes of the increased rot. Our own experiments cover physyological as well as biochemical changes in the sugar beet. Six samples of beet roots have been irradiated with gamma rays, from a Ce­siurn-137 source, at different doses in the range 7,5 - 240 Krad. Another sam­ple remained free of radiation and serves as 2 control.

Both, irradiated and non irradiated beets were stored for two months at constant temperature. The main scope of this storage period is to see the in­fluence of radiation in preventing sprouting, spoilage, loss of sugar and chemi­cal changes. Pertinent microbiological findings and observations made during the expe­riment pointed out that at 7,5 and 15 Krad radiation could be used as a mícro­biological treatment for beets, although at higher doses the micro-organisms were often less radiosensitive than their host. The irradiated beets were darker in colour than the control, mainly those receving larger doses. Sprouting inhibition was very effective at any dose were used. Softening of vegetable tissue appears inmediately after írradiation in all samples, including those receiving lower doses. But several weeks later the irradiated beets present musch hardness than the control. Sugar content decrcases at 21° C. more slowly in samples irradiated with lower doses than in the control. Little biochemical changes have been appreciated by means of chromato­graphic methods in the nitrogenous and carbohydrate fractions present in the beet The former of these fractions was weakly affected only by the higher doses. On the whole, irradiation at certain doses may be used to reduce loss of sugar, sprouting, and growlh of microbial flora, with a view to longer storage life of the sugar beet.

[ES] En este trabajo se comentan algunas aplicaciones de las radiaciones ionizantes a la mejora de plantas y a la conservación de estos produc­tos vegetales, discutiendo los resultados obtenidos por diversos investigadores. Respecto a la mejora de plantas, se estudia la irradiación de semi­llas para que den origen a plantas de mayores rendimientos, o la irradiación de plantas en diversas fases de desarrollo con objeto de que produzcan mayores cantidades de proteínas, azúcar, almidón, etc. En la conservación de alimentos, hemos hecho especial hincapié en la irradiación de raíces, bulbos y tubérculos comestibles, y pre­sentamos a la vez nuestras propias investigaciones sobre la irradia­ción de la remolacha azucarera con objeto de impedir su brotación, su enmohecimiento y la pérdida de azúcar durante el tiempo que per­manece ensilada en espera de su industrialización, pudiéndose prolon­gar el período de trabajo en las fábricas. Nuestras investigaciones consistieron en irradiar seis lotes de re­molacha a otras tantas dosis diferentes comprendidas entre 7.500 y 240.000 radiaciones de rayos gamma del Cs-137, otro lote igual se dejó sin irradiar y sirvió de testigo. La mitad de las remolachas de los siete lotes permaneció durante los dos meses que duró la experiencia a 21º C., temperatura normal de la raíz ensilada en las fábricas. Pero para estudiar la posible influencia de la temperatura se guardó la otra mitad de la remolacha a 7,5° C. Durante todo el tiempo que duró la experiencia se observó la textura y el crecimiento microbiano en las raíces, así como el color y las pérdidas de azúcar. También se han realizado unas determinaciones cromatográficas de las sustancias ni­trogenadas e hidratos de carbono.