加熱處理與介質研磨對山苦瓜抗氧化能力與降血糖功效之影響

Abstract

許多研究指出苦瓜具抗氧化、降血壓、抑癌和降血糖等保健功效，本研究探討以加熱處理與介質研磨對山苦瓜之抗氧化活性與降血糖作用的影響。在抗氧化分析中，比較不同加熱溫度之樣品，發現在清除DPPH能力測定、還原力、總抗氧化力與細胞抗氧化活性均隨著加熱溫度上升，其抗氧化能力逐漸下降；比較定溫於65℃與95℃下進行不同加熱時間之抗氧化能力，則顯示65℃不同加熱時間之樣品，隨著加熱時間的延長，其抗氧化活性逐漸下降；而95℃之加熱樣品，受到熱破壞後，其抗氧化能力不會隨加熱時間增加而改變；比較介質研磨樣品，發現細碎種籽懸浮液與介質研磨種籽懸浮液之抗氧化能力均優於細碎果肉懸浮液與介質研磨果肉懸浮液。在總酚含量分析中，顯示隨著加熱溫度增加，其酚類含量(20.00至13.35 mg GAE/g)逐漸下降；定溫於65℃下加熱，其酚類含量(20.00至12.36 mg GAE/g)隨加熱時間增加而下降；95℃下加熱不同時間，其酚類含量沒有顯著差異；而比較細碎處理與介質研磨處理，顯示細碎與介質研磨山苦瓜種籽的總酚含量(21.19與23.65 mg GAE/g)均高於細碎與介質研磨果肉部分(20.00與14.68 mg GAE/g)。 在評估降血糖功效中，以細胞模式進行葡萄糖攝入分析，顯示細碎山苦瓜果肉懸浮液經不同加熱處理之樣品，對於改善胰島素阻抗性之效果不明顯，可能是在加熱過程中造成有效成分的流失所影響，而細碎山苦瓜果肉懸浮液、介質研磨山苦瓜果肉懸浮液與介質研磨山苦瓜種籽懸浮液皆有改善胰島素阻抗性的能力，其中又以介質研磨山苦瓜種籽懸浮液之效果較顯著，推測可能是經過介質研磨的機械破碎撞擊，釋放出更多的活性物質所致。在降血糖成分分析中，以介質研磨山苦瓜種籽懸浮液之charantin含量最多(84.49 ug/g)，介質研磨山苦瓜果肉懸浮液(56.04 ug/g)與細碎山苦瓜果肉懸浮液(48.92 ug/g)，而經不同加熱處理的細碎山苦瓜果肉懸浮液之加熱樣品，其含量隨加熱溫度上升而減少；定溫下加熱不同時間之樣品，其charantin含量沒有明顯的變化。根據實驗結果顯示，山苦瓜果肉中的活性成分會受到加熱處理的影響。介質研磨種籽懸浮液有較佳的抗氧化活性，並且促進葡萄糖攝入能力。

Wild bitter melon is traditionally known for its medicinal properties such as antioxidant, anticancer, hypoglycemic, and cholesterol lowering effects. We explored the effects of heating treatments and media milling on antioxidative and hypoglycemic activities of bitter melon. Antioxidative activity was evaluated by cellular antioxidant activity assay along with other methods. Hypoglycemic activity was evaluated by glucose uptake activity. In antioxidant activity assays, the results showed that the antioxidant activities decreased as heating temperatures being increased. Prolonging heating time at 65℃ resulted in low antioxidant activity. There was no significant difference in the antioxidant activity among all the samples being heated at 95℃ with different heating time. Comparing to media milled samples, both blended and milled seeds had the higher antioxidant activities. The result of polyphenol content indicated that polyphenol content decreased from 20.00 to 13.35 mg CAE/g with increasing heating temperature. The polyphenol content decreased from 20.00 to 12.36 mg GAE/g at 65℃ with increasing heating time, however there was no significant difference in the polyphenol content of samples heated at 95℃ with different heating time. Both blended seed (23.65 mg GAE/g) and media milled seed (21.19 mg GAE/g) had higher polyphenol contents than blended and milled fruits (20.00 and 14.68 mg GAE/g) . Tumor necrosis factor-αwas used to induce insulin resistance of mouse liver FL83B cells in vitro. Insulin-resistance cells was used to observe glucose uptake activity, blended fruit, milled fruit and seed significantly increased glucose uptake in TNF-α-induced insulin resistance FL83B cells, especially milled-seed. The positive effect might be attributed to higher bioactive compounds in milled seed. The content of charantin in samples was following order: milled seed(84.49 ug/g)＞ blended (68.79 ug/g)＞blended fruit(56.04 ug/g) ＞milled fruit (48.92 ug/g). The content of charantin decreased with the heating temperature increased. Based on our findings, the bioactive compounds of bitter melon fruit were influenced by heating process. The milled seeds showed higher antioxidant activity and enhanced glucose uptake activity.