QUALITY OF ALFALFA SPROUTS GROWN FROM IRRADIATED SEEDS

Radiation environment in exploration-class space missions and plants' responses relevant for cultivation in Bioregenerative Life Support Systems

For deep space exploration, radiation effects on astronauts, and on items fundamental for life support systems, must be kept under a pre-agreed threshold to avoid detrimental outcomes. Therefore, it is fundamental to achieve a deep knowledge on the radiation spatial and temporal variability in the different mission scenarios as well as on the responses of different organisms to space-relevant radiation. In this paper, we first consider the radiation issue for space exploration from a physics point of view by giving an overview of the topics related to the spatial and temporal variability of space radiation, as well as on measurement and simulation of irradiation, then we focus on biological issues converging the attention on plants as one of the fundamental components of Bioregenerative Life Support Systems (BLSS). In fact, plants in BLSS act as regenerators of resources (i.e. oxygen production, carbon dioxide removal, water and wastes recycling) and producers of fresh food. In particular, we summarize some basic statements on plant radio-resistance deriving from recent literature and concentrate on endpoints critical for the development of Space agriculture. We finally indicate some perspective, suggesting the direction future research should follow to standardize methods and protocols for irradiation experiments moving towards studies to validate with space-relevant radiation the current knowledge. Indeed, the latter derives instead from experiments conducted with different radiation types and doses and often with not space-oriented scopes.

Effect of Red Cabbage Sprouts Treating with Organic Acids on the Content of Polyphenols, Antioxidant Properties and Colour Parameters

In recent years, there has been a great deal of consumer interest in consuming vegetables in the form of sprouts, characterized by high nutritional value. The disadvantage of sprouts is the loss of bioactive compounds during storage and the relatively short shelf life, due to the fact that they are a good medium for microorganisms, especially yeasts and molds. The aim of the study was to compare the content of polyphenols, antioxidant properties, color and microbiological quality of red cabbage sprouts preserved by the use of mild organic acids: Citric, ascorbic, lactic, acetic and peracetic. In the study, the content of polyphenols and antioxidant properties of sprouts was examined using the spectrophotometric method, instrumental color measurement was done using an “electronic eye” and the content of mold, yeast and the total number of mesophilic microorganisms was determined using the plate inoculation method. Taking into account the content of polyphenols and the antioxidant potential of sprouts, it was found that the addition of all organic acids contributed to the preservation of the tested compounds during their 14-day storage under refrigerated conditions, depending on the type of organic acid used, from 71 to 86% for polyphenols and from 75 to 96% for antioxidant properties. The best results were obtained by treating the sprouts with peracetic acid and ascorbic acid, respectively, at a concentration of 80 ppm and 1%. The conducted research on the possibility of extending the storage life and preserving the bioactive properties of fresh sprouts showed that the use of peracetic acid in the form of an aqueous solution during pre-treatment allows to reduce the content of microorganisms by one logarithmic order. Ascorbic acid did not reduce the content of microorganisms in the sprout samples tested. Considering the content of bioactive ingredients, as well as the microbiological quality of fresh sprouts, it can be said that there is a great need to use mild organic acids during the pre-treatment of sprouts in order to maintain a high level of health-promoting ingredients during their storage, which may also contribute to their prolongation durability.

Current intervention strategies for the microbial safety of sprouts

Sprouts have gained popularity worldwide due to their nutritional values and health benefits. The fact that their consumption has been associated with numerous outbreaks of foodborne illness threatens the $250 million market that this industry has established in the United States. Therefore, sprout manufacturers have utilized the U.S. Food and Drug Administration recommended application of 20,000 ppm of calcium hypochlorite solution to seeds before germination as a preventative method. Concentrations of up to 200 ppm of chlorine wash are also commonly used on sprouts. However, chlorine-based treatment achieves on average only 1- to 3-log reductions in bacteria and is associated with negative health and environmental issues. The search for alternative strategies has been widespread, involving chemical, biological, physical, and hurdle processes that can achieve up to 7-log reductions in bacteria in some cases. The compilation here of the current scientific data related to these techniques is used to compare their efficacy for ensuring the microbial safety of sprouts and their practicality for commercial producers. Of specific importance for alternative seed and sprout treatments is maintaining the industry-accepted germination rate of 95% and the sensorial attributes of the final product. This review provides an evaluation of suggested decontamination technologies for seeds and sprouts before, during, and after germination and concludes that thermal inactivation of seeds and irradiation of sprouts are the most practical stand-alone microbial safety interventions for sprout production.

Seed viability and functional properties of broccoli sprouts during germination and postharvest storage as affected by irradiation of seeds

The viability of broccoli seeds and functional properties, such as ascorbic acid, carotenoid, chlorophyll, and total phenol contents, of broccoli sprouts grown from irradiated seeds were evaluated. The seeds were irradiated using electron beam and gamma ray at doses up to 8 kGy. High germination percentages (>90%) were observed in seeds irradiated at < or =4 kGy, but the yield ratio and sprout length decreased with increased irradiation dose. Irradiation at > or =6 kGy resulted in curling of the sprout roots. Germinated seeds contained higher amounts of nutrients than raw seeds but the nutritional quality of sprouts decreased during postharvest storage. Radiation treatment hampered the growth of irradiated seeds resulting in underdeveloped sprouts with decreased ascorbic acid, carotenoid, and chlorophyll contents. In addition, the decrease in functional content of sprouts was more substantial in samples grown from high-dose (5 kGy) irradiated seeds than that of the low-dose (1 kGy) treated ones. Seed irradiation did not negatively affect the total phenol content of sprouts. In general, electron beam and gamma irradiation of broccoli seeds showed similar effects on the viability and functional properties of sprouts.

Combination of hot-water surface pasteurization of whole fruit and low-dose gamma irradiation of fresh-cut cantaloupe

Improvements in methods for disinfecting fresh-cut cantaloupe could reduce spoilage losses and reduce the risk of foodborne illness from human pathogen contamination. The objective of this study was to investigate the feasibility of using hot-water treatment in combination with low-dose irradiation to reduce native microbial populations while maintaining the quality of fresh-cut cantaloupe. Whole cantaloupes were washed in tap water at 20 or 76 degrees C for 3 min. Fresh-cut cantaloupe cubes, prepared from the washed fruit, were then packaged in clamshell containers, and half the samples were exposed to 0.5 kGy of gamma radiation. Native microflora populations and sensory qualities were evaluated during the subsequent 7 days of storage at 4 degrees C. The hot-water surface pasteurization reduced the microflora population by 3.3 log on the surface of whole fruits, resulting in a lower microbial load on the fresh-cut cubes compared with cubes cut from fruit treated with cold water. Irradiation of cubes prepared from untreated fruit to an absorbed dose of 0.5 kGy achieved a low microbial load similar to that of cubes prepared from hot-water-treated fruit. The combination of the two treatments was able to further reduce the microflora population. During storage, the headspace atmosphere of the packages was not significantly influenced by any of the treatments. Color, titratable acidity, pH, ascorbic acid, firmness, and drip loss were not consistently affected by treatment with irradiation, hot water, or the combination of the two. Cubes prepared from hot-water-treated whole fruit had slightly lower soluble solids content. The combination of hot-water pasteurization of whole cantaloupe and low-dose irradiation of packaged fresh-cut melon can reduce the population of native microflora while maintaining the quality of this product.

Irradiation to kill Escherichia coli O157:H7 and Salmonella on ready-to-eat radish and mung bean sprouts

A study was carried out to evaluate the effectiveness of ionizing radiation in eliminating Escherichia coli O157:H7 and Salmonella on commercial ready-to-eat radish and mung bean sprouts and to assess the chemical and physical quality of these sprouts. The use of ionizing radiation was investigated as a means of reducing or totally inactivating these pathogens, if present, on the sprouts. Treatment of mung bean and radish sprouts with a dose of 1.5 and 2.0 kGy, respectively, significantly reduced E. coli O157:H7 and Salmonella to nondetectable limits. The total vitamin C content was gradually reduced with the increase in irradiation dose (P < 0.0001). However, the effect of storage interval on the loss of vitamin C was nonsignificant for radish sprouts and significant for mung bean sprouts (P < 0.04). The color, firmness, and overall visual quality of the tested sprouts were acceptable when effective doses were applied to both radish and mung bean sprouts. Therefore, ionizing radiation could be useful in reducing the population of pathogens on sprouts and yet retain acceptable quality parameters.

Changes in growth and antioxidant status of alfalfa sprouts during sprouting as affected by gamma irradiation of seeds

Viking 3000 alfalfa seeds irradiated with gamma rays to doses of 0, 1, 2, 3, or 4 kGy were sprouted and allowed to grow for up to 8 days at 23 degrees C. Germination, growth (yield and length), antioxidant capacity, and ascorbic acid (AA) were measured during sprouting. Results showed percent germination of the seeds and the rates of growth of the sprouts were inversely related to the radiation dose absorbed by the seeds. Both antioxidant capacity and AA content expressed on a fresh weight basis decreased during growth of the sprouts. Sprouts grown from irradiated seeds had greater antioxidant capacity and AA content on a fresh weight basis than those grown from nonirradiated seeds. However, when the nutritive values were expressed on a per gram of seed basis, irradiation had no effect on the nutritive values of sprouts.