高靜水壓技術降低鳳梨釋迦果泥升糖指數之健康價值研究

Abstract

糖尿病為目前國人十大死因之第五名；2014 年全球糖尿病成年人口高達 4.22 億人。此外，發病年齡正逐漸年輕化。為減輕身體負擔，糖尿病友多選食低升糖指數 (glycemic index，GI) 之食品以控制其血糖波動。鳳梨釋迦 (Annona cherimola × Annona squamosal, atemoya) 雖富含膳食纖維，但其糖度高達 22.3 ~ 23.0°Brix，含糖量高而不適合糖尿病友食用，加上近年氣候不穩定使其異常後熟落果、表皮褐變而影響品質，使其難以銷售。高靜水壓技術 (high hydrostotic pressure processing，HHP，高壓) 是目前於食品加工產業上蓬勃發展的新興技術之一，其具有非熱殺菌、富化生物活性成分、影響酵素活性、降低過敏原等功能。 本研究探討以高靜水壓技術對於鳳梨釋迦泥升糖指數之影響。分別以 100、 300、 600 MPa 處理鳳梨釋迦果泥 15 分鐘，並餵食 Sprague-Dawley 大鼠測其餐後 2 小時內血糖濃度變化以計算 GI 值。結果顯示 300 及 600 MPa 處理能夠延緩餐後血糖的上升，而以 600 MPa 處理最能夠顯著降低其升糖指數，自 65.4 降至 49.8。探討相關作用因子方面，成分分析上，高壓處理鳳梨釋迦果泥於游離糖、果膠、多酚、膳食纖維含量無顯著影響，顯示此與 GI值下降無關；而三種高壓處理皆能提升類黃酮含量，由於類黃酮含量的增加而使其具有抑制人體 α- 葡萄糖苷酶以及α- 澱粉酶之能力，為降低 GI值的因素之一。於物理性因素的部分，高壓處理能夠提升鳳梨釋迦果泥之黏度，尤以 600 MPa 之處理最為顯著，且趨勢與動物實驗測定之升糖指數結果相同，推論高壓使黏度提升為降低 GI 值影響因素之一。酵素活性分析中，高壓處理之蔗糖轉化酶 (Sucrose invertase，SI)、果膠甲酯酶 (Pectin methylesterase，PME)、聚半乳醣醛酸酶 (Polygalacturoase，PG) 的活性皆顯著下降，其中以 600 MPa 處理最為顯著，因此推論降低 SI 活性使果泥中的葡萄糖生成速度降低；降低 PME 及 PG 的活性使果膠結構較穩固而葡萄糖難以被小腸吸收，進而使 GI 值降低。總結以600 MPa 處理使類黃酮含量增加及黏度顯著提升，並顯著降低 SI、 PG 及 PME 活性，進而延緩葡萄糖自鳳梨釋迦果泥中的轉化及釋放，而達到顯著降低升糖指數的效果。

Diabetes mellitus is currently the fifth leading cause of death for Taiwanese; Global diabetic adult population reached 422 million in 2014. In addition, the age of onset is getting younger and younger. To reduce the the body stress, the patients with diabetes choose to eat low-glycemic index (GI) foods to control their blood glucose fluctuations. Although rich in dietary fiber, the sugar content of atemoya (Annona cherimola × Annona squamosa) is up to 22.3 to 23.0°Brix. It isn't suitable for diabetics because of its high sugar content. In addition, climate instability has caused abnormal ripening and skin browning of fruit in recent years. It affected the quality, making it difficult to sell. High hydrostatic pressure processing (HHP) is one of the emerging technologies that are currently flourishing in the food processing industry. HHP has the functions of non-thermal sterilization, enrichment of bioactive compounds, influencing the activity of enzymes, and reducing allergenicity. This research studies the effect of high-pressure treatment on the glycemic index of atemoya puree. The atemoya puree was treated with 100, 300, and 600 MPa for 15 minutes, and fed to the Sprague-Dawley rats to measure changes in blood glucose level within 2 hours after meal to calculate GI value. The results showed that the HHP with 300 and 600 MPa can retard the increase of postprandial blood glucose, while the treatment with 600 MPa could significantly reduces the glycemic index of atemoya puree. To investigate the relevant factors, in the composition analysis, the HHP has no significant effect on free sugars, pectin, polyphenols and dietary fiber content in atemoya puree, indicating that these are irrelevant with the decline in GI value. Due to the increase of flavonoid content, it has the ability to inhibit the α-glucosidase of human, which is one of the factors that reduce the GI value. In terms of physical factors, HHP can increase the viscosity of atemoya puree, especially at 600 MPa, which is in correspond with the result of animal experiments. It is inferred that HHP increases the viscosity to reduce the GI value. In enzyme activity analysis, the activities of sucrose invertase (SI), Pectin methylesterase (PME), and polygalacturoase (PG) were significantly decreased. The treatment with 600 MPa is the most significant. Therefore, it is inferred that reducing the SI activity results in a decrease in the rate of glucose production in the puree; decreasing the activity of PME and PG makes the pectin structure more stable and the glucose is absorbed hard at the small intestine. Summing up the HHP/600 MPa increased the content of flavonoids and increased the viscosity , and significantly reduced the activities of SI, PG and PME, and thus retarded the conversion and release of glucose from the atemoya puree, then achieved a significant reduction in glycemic index.