Browsing by Subject "vaaleneminen"

Peeling of carrot removes the epidermis and some sub-epidermal tissue. The new outer layer of cells is damaged, and it causes leakage of cellular fluids. The peeled surface is replaced by a new protective layer which is white material. Surface whitening is most likely due to drying of the outer tissue, lignin synthesis, or decreased carotenoid levels during storage of the carrot. The aim of the dissertation was to find efficient processing methods for controlling the surface whitening of carrot. Controlling surface whitening is important because from a consumer perspective it is a sign of a loss of freshness. Efforts were made to control the discoloration of the carrot surface with help of enhanced polishing, acidity control and edible film. The processing methods were as follows: twice polished (A), three times polished (B), three times polished + citric acid (C), three times polished + edible film (D). After polishing all the samples were immersed in ozonated water (0,3 ppm, 4 min). The samples were packed in LDPE or OPP packages. The samples were stored for 16 days at temperature of +4–6 ̊ C. Quality changes of the samples were assessed by packaging gas content, surface pH, colour measurements, images, microscopic images, microbiological quality and sensory evaluation. Processing with citric acid (C) and edible film (D) slowed formation of white surface for up to seven days, after that the differences between the processing methods decreased so much that they could not be detected any more. Sensory evaluation was done after nine days of storage. The appearance of the fresh-cut carrots was least white when the processing method was D and packaging material LDPE. Off-flavours detected were most likely due to natural taste variation of carrots.