| Summary: | 碩士 === 國立宜蘭大學 === 園藝學系碩士班 === 103 === The ‘Yilan Red’ guava fruit was placed under 35, 25, 15, and 10℃ for 11 days. The decay rate gradually increases with increases in storage temperature and time, reaching 100% in day 3, 4, 9, and 11. The weight loss rate of the fruit rapidly increase with an increase in temperature, reaching 7% on day 3 at 35℃. The four storage temperatures has no obvious effect on the L* value of the peel color, but with an increase in storage time, the value slightly decreases (slightly turns dull); the a*value of the peel color at 35 and 25℃ turns from a negative value to a positive value (the color turns from green to red); at 15 and 10℃, the values are both negative (green); the b*value, maintained at 45-50 show stability with little change. However, with an extended storage period, it slightly increases (slightly turns yellow). The fruit firmness decreases from 9 on day 0 to 2, 2, 3, and 6N on day 3.; at 35, 25, 15℃, and 10℃, the two groups show obvious differences in temperature. The total soluble solids content of the fruit show little change during the 11 days, maintained at around 9℃ °Brix. The titratable acidity 35 and 25℃ reduce from 0.5% to 0.4%, while 15 and 10℃ show no change, maintained at 0.5%. The ascorbic acid content at the four storage temperatures during the storage period is between 150mg to 190mg/100ml, showing no trend of consistency. The fruit placed under 35 and 25℃ reach the peak in respiration rates one after another by day 3 and day 4, while at 15 and 10℃, the shelf day 9 and 11 show low and flat respiration rates. At 35 and 25℃, the ethylene production reaches the peak on day 3 and 4; at 15 and 10℃, the ethylene production is low and flat. The ‘Jong-Shan Yueh Bar’ guava fruit is placed at 35, 25, 15, and 10℃ for eight days. The decay rate reaches 100% on day 2, 3, 6, and 7. The weight loss rate of the fruit increases as the storage temperature increases. At 35℃, the rate reaches 9% on day 3; at 10℃, the rate reaches 6% on day 8. The L* value of the peel color stored at four temperatures decreases with increases in storage time (slightly turns dull); the a* value turns from a negative value to a positive value (turns from green to red); the b* value of the peel color at 35 and 25℃ is 45; at 15℃, it is 48; at 10℃, it is 52. Additionally, the value slightly increases with increases in storage time (slightly turns yellow). The fruit firmness increases with an increase in storage temperature and decreases with an increase in time. At 35, 25, and 15℃, it reaches below 3N on day 3; at 10℃, it is maintained at over 6N. The temperatures of the two groups show significant differences. The total soluble solids content of the fruit at four storage temperatures is maintained at 9-10 °Brix. During the 8-day shelf period, no significant change is seen. The titratable acid content for storage temperatures of 35 and 25℃ decreases from 0.6% to 0.4%; at 15 and 10℃, it is maintained at around 0.6%. The ascorbic acid content at four storage temperatures is between 150mg and 220mg/100ml, without the trend of consistency. The respiration rate of the fruit at 35 and 25℃ reach the respiration peak on day 3 and day 4; at 15 and 10℃, the respiration rate is low during the shelf period; it is flat and without a peak generated. On the other hand, ethylene production at 35 and 25℃ reach the peak on day 1 and day 4, which subsequently decreases; at 15 and 10℃, the ethylene production is extremely low and without change. The shelf life of the ‘Yilan Red’ guava fruit placed at 35, 25, 15, and 10℃ is 2, 3, 8, and 10 days respectively; the shelf life of the ‘Jong-Shan Yueh Bar’ guava fruit is 1, 2, 5, 6 days respectively. Among the four storage temperatures, at 10℃, there is better quality and a longer shelf life.
For the ‘Yilan Red’ guava fruit, after room cooling(10±2℃) treatment packaged fruit (Polystyrene net sleeve and PE bag) and naked fruit show stable temperatures after 340 and 240 minutes, 13.8 and 11.3℃ respectively. After 1/2 of cooling time treatment in the room cooling, the temperature decreases to 17.5℃, the packaged fruit requiring130 minutes, and the naked fruit requiring 60minutes. After the hydrocooling (3±1℃) treatment, the packaged fruit and naked fruit reach stable temperatures after 100 and 50 minutes, 3.4 and 2.2℃ respectively. After hydrocooling at 1/4, 1/2, and 7/8 cooling time, the temperatures reduce to 19.5, 14.0, and 5.8℃ respectively, the packaged fruit requiring 3, 11, and 54 minutes; the naked fruit requiring 1,3, and 14 minutes. After storage in the room cooling at 25℃, the fruit decay rate is 60% for packaged fruit on day 6; it is 100% for the control group; the rate for naked fruit on day 6 is 40% ; it is 60% for the control group. Through three kinds of hydrocooling (1/4, 1/2, and 7/8 cooling time), when stored at 25℃, the decay rate is 0% for packaged fruit on day 3 ; it is 40% for the control group; for the naked fruit, the rate is 0% on day 3 ; it is 20% for the control group. Stored at 25℃ in the room cooling, the weight loss rate for the packaged fruit on day 9 is 1% ; it is 3% for the control group; for the naked fruit, the rate is 5% on day 9 ; it is 8% for the control group. Stored at 10℃, the weight loss rate for the naked fruit on day 12 is 5% ; it is 6% for the control group. Stored after 25℃ through three kinds of hydrocooling, the weight loss rate for the packaged fruit on day 9 is 0% ; it is 2% on day 9 for the control group; for the naked fruit, the rates are 4%, 5%, and 4% respectively on day 9 ; it is 6% for the control group. Stored at 10℃ through three kinds of hydrocooling, for the naked fruit, all the three are 4% after 12 days ; it is 5% for the control group. Stored at 25℃ in the room cooling, the L* value of the peel color rapidly increases for both the packaged fruit and the naked fruit (brighter fruit peel); stored at 10℃, the degree of increase for the packaged fruit and naked fruit is slower. Stored at 25℃ in the room cooling, the a*value of the peel color increases from -12 to 4 after 6 days (the fruit’s green fades out) ; it is 8 for the control group (more green fades out). Stored at 25℃ through three kinds of hydrocooling, the a*value of the peel color increases from -12 to 5 , 3, and 1 (fruit green fades) after 6 days ; it is 5 for the control group. At 25℃, under the four kinds of precooling methods and at 25℃, the b*value of the fruit peel color for the packaged fruit and naked fruit increases from 43 to 50 on day 6 (turns yellow); stored at 10℃, the value for the packaged fruit and naked fruit increases to 50 on day 12 (turns yellow). Stored at 25℃ in the room cooling, the fruit firmness for the naked fruit is 9N on day 3 ; it is 2N for the control group; stored at 10℃, the naked fruit is 22N on day 3 ; it is 18N for the control group. Stored at 10℃ the fruit firmness on day 3 for the packaged fruit through three kinds of hydrocooling is 10, 15, and 17N respectively ; it is 7N for the control group.
For the ‘Jong-Shan Yueh Bar’ guava fruit after room cooling treatment (10±2℃), the packaged and naked fruit show stable temperatures after 240 and 150 minutes respectively, 11.3 and 11.2 ℃ respectively. After 1/2 of cooling time treatment in the room cooling, the temperature decreases to 17.5℃, the packaged fruit requiring 40 minutes and the naked fruit requiring 10 minutes. After hydrocooling (3±1℃), the packaged fruit and naked fruit show stabilize temperatures after 120 and 150 minutes respectively, 3.3℃ and 2.6℃ respectively. After 1/4, 1/2, and 7/8 of cooling time through cooling, the temperatures decreases to 19.5, 14.0, and 5.8℃ respectively, the packaged fruit requiring 2, 15, and 60 minutes and the naked fruit requiring 1, 4, and 17 minutes. Stored through room cooling at 25℃, the fruit decay rate for the naked fruit is 0% on day 3 ; it is 20% for the control group. Through three kinds of hydrocooling (1/4, 1/2, and 7/8 cooling time, stored at 25℃, the decay rate for the naked fruit on day 6 is 40% ; it is 60% for the control group. Stored at 25℃ through room cooling, the weight loss rate for the naked fruit on day 6 is 6% ; it is 9% for the control group; stored at 10℃, the naked fruit is 4% on day 9 ; it is 5% for the control group. Stored at 25℃ through three kinds of hydrocooling, the weight loss rate for the packaged fruit is 1%, 0%, and 0% for the on day 6 ; it is 1% for the control group. The rates for the naked fruit on day 6 are 7%, 6%, and 6% respectively; it is 7% for the control group. Stored at 10℃ through three kinds of hydrocooling, the weight loss rates for the naked fruit on day 9 are 6%, 4%, and 4% respectively; it is 6% for the control group. Stored at 25℃ through three kinds of room cooling, the L* value of the peel color for the packaged fruit and naked fruit increases from 60 to 70 after 6 days (fruit peel turns brighter); stored at 10℃, the increase is slow, maintained at 60-65. Stored at 25℃ through room cooling, the a*value of the peel color for the packaged fruit on day 6 turns from -13 to 3 (green fades), and the control group is 6 (more green fades). Stored at 25℃ through three kinds of hydrocooling, the a* value of the peel color increases from -13 to 2, 2, and 1 on day 6, the control group is 5. At 25℃ through four kinds of precooling methods, the b* value of the peel color for the packaged fruit and naked fruit increases from 45 to 50 on day 3 (slightly turns yellow); stored at 10℃, the fruit firmness for the packaged fruit is 11N on day 3 ; it is 3N for the control group. Stored at 10℃ through three kinds of hydrocooling, the fruit firmness for the naked fruit on day 3 is 15, 15, and 14N respectively, and the control group is 8N. In summary, the ‘Yilan Red’ guava fruit and the ‘Jong-Shan Yueh Bar’ guava fruit, through precooling (room cooling and three kinds of hydrocooling), can maintain better quality and increase the shelf life through packaged and naked fruit stored under a low temperature (10℃).
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