Browsing by Subject "pakkauskalvojen perforointi"

The aim of this thesis was to define optimal packaging conditions for four fresh ready-to-cook and pre-cut vegetable mixes. The packaging conditions consisted of perforated and non-perforated film which were investigated in two different gas mixtures. One of the gas mixtures consisted of modified atmosphere which was chosen in advance and the other gas mixture consisted of normal atmosphere. The literature study focused on the negative influences of processing methods on the physiological properties of vegetables. The main principles of packaging solutions by which negative influences of fresh-cut produce could be minimized with were also mentioned. The main target of the experimental study was to examine if perforated films could be used for avoiding of in-package anaerobic respiration which is a common reason for vegetable spoilage. The respiration rates of the products were measured and with the results an optimally perforated film was defined for each product. The gas concentrations were measured electronically and the quality of the products were evaluated with sensory evaluations and microbiological determinations. Electronically measured gas concentrations were verified gas chromatographically and also the water vapour transmission properties of the films were studied. With perforated film and modified atmosphere gas concentrations remained most constant and they were mainly held in aerobic respiration level. With other packaging solutions very low oxygen levels and very high carbon dioxide levels were observed which was also noticed in the sensory evaluations where off-odours and off-flavours were discovered. With perforated film and modified atmosphere the growth of yeasts, molds and bacteria was smaller than with perforated film and normal atmosphere. The verification of the gas measurements was successful and gas concentrations which were measured both electronically and gas chromatographically were on the same range though minor differences in the accuracy of the results were discovered. The most optimal packaging solution for tested products was achieved with perforated film and modified atmosphere.