殺菁處理條件與低溫保存對茄子物性品質及機能性成分的影響

• Main Author: 姚量豪
• Other Authors: 黃健政
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/16993943722896376853

碩士 === 國立嘉義大學 === 食品科學系研究所 === 104 === Eggplant belongs to tropical plants, with economic importance in tropical and subtropical regions. Eggplant can be easily injured by heat or physical damage and lead to the cell enzymes outflow, browning, anthocyanins loss, and therefore, shorten shelf life. Common eggplants of Taiwan, including Yanzhi and Machi eggplant were chosen as raw materials in this study. Middle part of eggplants were soaked in calcium chloride solution(1%) for 1 hour then blanched in tap water, citric acid solution (0.5%), deep ocean water (0.5%), magnesium sulfate solution (0.5%) for 5 minute respectively, followed by ice-bath and vacuum packaging. Treated samples were stored under -18℃ and 4℃ before periodically analysis of color parameter, texture, anthocyanins content, flavonoids content, content of total phenolic compound, DPPH radical scavenging ability, enzyme activity, microbiology, structure under microscope, and sensory evaluation. Color parameter of eggplants of both species could be remained after blanching. Increment in L* and decreased in a* and b* were determined after blanching and frozen storage. In comparison, hardness of Yanzhi eggplant was higher than Machi eggplant after soaking with calcium chloride solution. However, texture of both species were softened after blanching and frozen storage, although the eggplants were still chewable in mouthfeel, and there were no differences in four types of blanching solutions. As the result of functional composition analysis, highest anthocyanin retention was determined in eggplants blanched with deep ocean water, which preserved up to 64.89% of anthocyanins in Yanzhi eggplant and 77.13% for Machi eggplant due to high concentration of magnesium ion that might provide protection to anthocyanins chelating ability. On the other hand, significant decreased in polyphenol oxidase (PPO) and peroxidase (POD) activity was determined in Yanzhi eggplant after blanching. Microorganism was not detected in all treatment groups. Obvious pores and filamental tissue were observed in fresh eggplants under microscope but pores shrank after soaking in 1% calcium chloride for 1 hour. The overall sensory scores of Machi eggplants were higher than Yanzhi eggplants. Color of the Yanzhi eggplants could still be remained after 4℃ refrigeration storage for 14 days but browning occurred after 28-day storage while browning only occur in Machi eggplants after 35-day refrigeration storage. Decrement in L* and increment in b* were determined after browning. Significant decreased in hardness was found in both eggplants after 21 days and softening was found in Machi eggplant after 21 days. Functional compositions were decreased in trend after 21-day storage and found to be significant after 28 days, especially in anthocyanins content of Yanzhi eggplant that degraded completely and 40 % anthocyanins were retained in Machi eggplants. Lowest loss in flavonoid content and total phenolic compound were found in the group blanched with magnesium sulfate solution that decreased 71.98 % of flavonoid and 46.06 % of total phenolic compounds in Yanzhi, and 49.93 % and 45.27 % in Machi. Decreased in DPPH radical scavenging ability was also found. Activity of PPO and POD was found in a stable trend lower than 1 UEA in all treatment groups and no microorganism was detected within 28-day refrigeration storage. 180-day frozen stored eggplants which blanched with tap water and deep ocean water were thawed and microwaved for 15 and 30 seconds, or air-contact for 30 and 60 minutes to imitate consumers’ action on ready-to-eat eggplant. The samples were then analyzed for color, texture, anthocyanins and flavonoid content, total phenolic compounds, and DPPH radical scavenging ability. Physical properties and functional composition of frozen eggplants were affected by microwaving, increased in b* of color parameter but remained blueness. Softer structure was found in texture of Machi eggplant due to serious damaged by heating. In comparison, deep ocean water provided better protection to anthocyanins, total phenolic compounds and flavonoid of both eggplants and therefore, higher DPPH radical scavenging ability. However, the longer microwaving time, the more serious damage in physical properties and functional complexes. Air contact mainly led to changes in functional complexes of frozen eggplants, but allowed retention of blueness in both eggplants and insignificant softening in texture. The longer air contact period, the more serious changes in functional composition. Therefore, deep ocean water could provide better protection on functional composition of eggplants.