Browning Inhibition Of Fresh-cut Potato

Fresh-cut fruit and vegetable play an important role in food industry. As one of the most consumed agricultural products, the fresh-cut product of potato has a really wide space of development. Browning is the main reason lowered the quality and limited the shelf life of fresh-cut potato. In this thesis, effect of cultivar and pre-cutting storage time and temperature on the quality of fresh-cut potato was investigated. Inhibition of controlled atmosphere storage, heat shock, ethanol and other widely used chemicals on browning were studied on potato with highest browning potential. Through the course, the most effective way in inhibiting browning was chosen to extend the shelf life of fresh-cut potato. The result showed that:1. The browning susceptibility of fresh-cut potato slices differed among potato cultivars. Among the four potato cultivars, California white flesh and skin potato, Washington white potato, Klamath Red Potato and Russet potato, used in this paper, Russet potato with highest browning was no longer marketable in a short time (less than 4 days at 5℃) after cutting. However, potato slices from California white flesh and skin potatoes were still salable even after 12 days storage at 5℃. There was no significant difference in individual phenolic content among four cultivars.2. Quality of fresh-cut potato was affected by pre-cutting storage time and temperature. With the extending of storage time, browning potential of potato slices was increased, and the total phenolic acid content was first increased and then declined. Phenolics in potatoes stored at lower temperature (0℃) was synthesized and accumulated faster than those stored at 5℃and 10℃. However, for those stored at higher temperature (10℃), sprouting and softening tissue were found after 3 months storage. According to this experiment, 5℃was the most suitable storage temperature for potatoes used for fresh-cut.3. Pre-cutting (1, 2, 3 min) or post-cutting (10, 15, 20 min) heat shock treatment (52.5℃) had no effect on inhibiting browning and maintaining the quality of fresh-cut potato slices. To some extent, the browning was even accelerated.4. Other widely used browning inhibitors, such as ethanol (2.5%, 5%, 7.5% and 10%), salicylic acid (0.5g/L, 1g/L), sodium chloride (1%), zinc chloride (1%), EDTA-2Na (2g/L, 4g/L) and oxalic acid (5 mmol/L), were completely ineffective on fresh-cut potato. A calcium chloride dip resulted in some retardation of browning on cutting potato, though the effect was not significant. Citric acid (1.25%) and ascorbic acid (1.25%) dips used alone were ineffective, but their combination provided some benefit to browning inhibition. Compared with others, sodium bisulfite dips were most effective in retarding surface browning. Even with very low concentration (0.05%), it still effectively inhibited browning and prolonged the shelf life to 8 days.5. Reducing O₂ from 21% in air to 3 or 0.3% had little effect on browning inhibition. Potato pieces stored in 12% CO₂ combined with 0.3 or 3% O₂ showed less browning, higher overall quality, and less change in color values than those stored in 6% CO₂. Likely, an O₂ concentration as low as 0.3% was less effective than 3% in maintaining the quality of fresh-cut potato. The appropriate storage atmosphere for fresh-cut Russet potato was 3% O₂ + 12% CO₂.6. The browning, increasing of PAL activity, synthesis of phenolics and chlorogenic acid were significantly suppressed by controlled atmosphere storage (3% O₂ + 12% CO₂) combined with sodium bisulfite(0.25%, 0.025%) or citric acid + ascorbic acid (AA + CIA, 1.25% + 1.25%). However, they showed no marked difference in reducing the acticvity of PPO and the synthesis of caffeic acid, gallic acid and protocatechuic acid. When combined with CA with sodium bisulfite, 0.025% sodium bisulfite extending the shelf life to 8 days while 0.25% sodium bisulfite extending it to 16 days.