engleski

Quality improvement in plum spirit technology using gamma radiation

Background of the study. Gamma radiation is a very well-known and well-established non-contact physical method for microbial decontamination of food, preserving food and increasing its shelf- life. Since this process is non-thermal, gamma irradiation is often called a cold-pasteurisation method. Consequently, this method can be potentially applied in different technologies for food storage and processing. Considering the known fundamental effect of ionizing radiation in complex material like food is, an original assumption is made that gamma irradiation applied in food processing could result in cleaner fermentation and favorable chemical composition of fermented fruit mash. This assumption could be valid also for distillates. It is known that due to its toxicity, methanol is an undesirable fraction in distillation process, which must be separated very carefully, which is not always easy to achieve in conventional technologies. Therefore, there is a need in spirit technologies to find the appropriate method and conditions for a possible reduction of methanol formed during the mashing process thus reducing the possibility of the presence of traces of methanol in the distillate. The aim of this research was to confirm the assumption above and suggest gamma radiation as a potential method for improvement of quality and technology for preparation of fruit distillates. Methodology. Plums cv. Elena (Prunus domestica) were subjected to gamma irradiation at the panoramic 60Co source at the Radiation Chemistry and Dosimetry Laboratory at the Ruđer Bošković Institute. Irradiation were performed in the air at two irradiation doses (5 and 10 kGy) and the dose rate of 1.1 kGy/h. After de-stoning and mashing fermentation was conducted with Saccharomyces cerevisiae var. bayanus yeast strain. Distillates from the irradiated plums mash were produced by using a simple pot still. After preparation procedures, the samples of distillates were analyzed by gas chromatography (Shimatzu, GC2010) and organoleptically. Results. In comparison with the control sample, GC-FID analysis of distillates determined an impact of irradiation on the methanol content and reduction rate of 2 mg/mL a.a. (absolute alcohol) at the dose of 5 kGy and 3 mg/mL a.a. at the dose of 10 kGy, respectively. Moreover, distillates produced from irradiated plums showed the favorable composition of other volatile compounds. The concentrations of acetaldehyde and ethyl acetate decreased with the increasing absorbed irradiation dose, while higher alcohols (3-methyl- 1-butanol, 2-methyl-1-butanol, 1-propanol, 2- methyl-1- propanol) were not affected by irradiation significantly. Conclusion. Results obtained suggest that ionizing irradiation might be a suitable method for methanol reduction alternative other conventional technologies. Simultaneously better chemical properties in plum spirit could be achieved as compared with non-irradiated samples.

fruit distillates, gamma radiation

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