WPŁYW TECHNOLOGII MINIMALNEGO PRZETWARZANIA NA JAKOŚĆ SENSORYCZNĄ I MIKROBIOLOGICZNĄ ORAZ ZAWARTOŚĆ ZWIĄZKÓW BIOLOGICZNIE AKTYWNYCH W JARMUŻU (BRASSICA OLERACEA L. VAR. ACEPHALA DC.)

Abstract

Introduction. The increasing social awareness of the significance of food for the maintenance and improvement of health and quality of life caused consumers’ growing interest in the quality of meals. The role of fruit and vegetables as dietary components is unquestionable. Cabbage vegetables, especially kale, are sources of various highly bioactive compounds such as phenolics, carotenoids and glucosinolates, which exhibit anticancer activity. It is possible to reduce the influence of treatments applied in the technological process on the characteristics of processed raw materials by minimal processing of fruit and vegetables. Minimal processing technologies are modern techniques, which enable the production of food of sufficient durability for distribution, which meets consumers’ demands for convenience and high quality. Scientific publications do not provide much data about the influence of minimal processing treatments, including packaging in high-oxygen modified atmosphere, on the content of bioactive compounds in products.The aim of the study was to determine the influence of treatments applied in the technological process, packaging and storage in modified atmosphere, especially high-oxygen atmosphere, on the sensory and microbiological quality as well as changes in the content of bioactive compounds in minimally processed kale. Materials and methods. Green (Reflex cultivar) and red (Redbor cultivar) raw kale (Brassica oleracea L. var. acephala DC.) was the research material. The aim of the study was achieved by using current methods of research and analysis. Packaging with various materials and atmospheres was analysed. Changes in gas concentrations inside packages with minimally processed products were monitored. The microbial contamination of the raw materials and products was assessed. Bioactive compounds were analysed with chromatographic methods. The results were analysed statistically to confirm or exclude the significant influence of the factors under study on the determinants of quality factors and to indicate correlations between parameters. Results. The study provides data on the sensory and microbial quality of kale washed with tap water and rinsed with solutions of organic acids or chlorinated water. The material was packed and stored in a modified atmosphere with different oxygen and carbon dioxide content, including a high-oxygen atmosphere. The oxygen permeability of solid or microperforated packaging materials ranged from 1.5 to 3000 cm3/m2/24 h·atm. Apart from that, the influence of selected packaging conditions on the profile and content of phenolic compounds, glucosinolates, carotenoids, vitamin C and volatile sulphur compounds was analysed. The influence of high-oxygen and low-oxygen atmosphere on various qualitative aspects of minimally processed kale was compared. Conclusions. The study showed that a high-oxygen atmosphere with 80% of O2, 10% of CO2 and 10% of N2 and the packaging material with an oxygen permeability of 3000 cm3/m2/24 h·atm were the best packaging and storage conditions for minimally processed kale. These packaging conditions and the pretreatment of kale with a solution of ascorbic and citric acids reduced the physiological activity of the product, resulted in its high sensory quality and decreased its microbiological contamination during 12 days of storage. The treatment with the solution of organic acids and packing in the high-oxygen atmosphere reduced the microbiological contamination of kale comparably or significantly higher than the treatment with chlorinated water. In addition, these processing and packaging conditions enabled retention of the high content of phenolic compounds in the product. The low-oxygen modified atmosphere enabled retention of the high content of glucosinolates. The loss of carotenoids was reduced by using microperforation of packaging material with 333 holes, diameter of 70 μm/m2.