The influence of irradiation and packaging on the quality of prepacked vegetables.

During storage, transport and sale of prepacked vegetables, their quality deteriorates very quickly by microbiological decay, discolouration and desiccation. The experiments described were carried out with endive (Chichorium endiva L.) as a representative of the leaf vegetables. After processing (cutting, washing and drying), the product was packed in polythene bags without and with 4 perforations of 2 mm diameter. The endive was irradiated with 0 and 100 krad gammarays and afterwards stored at 10 degrees C, thus simulating the transport and sale temperature. The quality was studied on the basis of the following parameters. The gas composition in the bags, the microbiological composition, the Vitamin C (Ascorbic acid + Dehydroascorbic acid) content and the sensory quality. The experiments showed that the modified gas composition in the non-perforated bags, caused by the respiratory activity of the cut product, improved the quality. The low O2 and high CO2 content prevented discolouration, retarded the senescence and diminished the Vitamin C losses. The initial Total Viable Count of endive was 10(6) to 10(7) and the number of Enterobacteriaceae amounted to approx. 10(5) g-1 product, and increased in a couple of days to 10(8) and 10(7) g-1 respectively, resulting in decay of the product. The contamination with aerobic and anaerobic spores was low, viz. 10(1) to 10(2) g-1 and did not increase at 10 degrees C. An irradiation treatment of 100 krad reduced the Total Viable Count and the Enterobacteriaceae with 3-4 decimals, by which the shelf life increased with about 100% and almost all the Enterobacteriaceae were eliminated, so that the hygienic quality was improved. In prepacked endive nearly half of the Total Vitamin C content was lost within two days. The retention was strongly affected by the presence or absence of perforations; the effect of an irradiation treatment was slight.