| Abstract: | 本研究以市售乳粉為材料，添加維生素與不飽和脂肪酸EPA及DHA等機能添加物後，探討鐵質來源(二價亞硫酸鐵、三價氯化鐵及二價與三價各50% 之混合鐵劑)、脂肪含量(0.3、1.5及3.5%)與不同方式包裝下(一般包裝及真空包裝)，藉體外酵素水解試驗探討保存期間其鐵質生物?用效?之變化，以可透析二價鐵(DFe(Ⅱ))、可透析總鐵(TDFe)、未透析二價鐵(NDFe(Ⅱ))及總二價鐵(DFe(Ⅱ)+NDFe(Ⅱ))四項數值作為評估指標。結果顯示，3.5%脂肪含量處理組有最高之鐵質生物利用效率，EPA的添加則可提高鐵質在乳粉中的生物利用性，隨著保存時間之延長，乳粉中之鐵質生物價亦會增加，特別是針對二價鐵質之部份具有穩定之效果(DFe(Ⅱ)+NDFe(Ⅱ))。另一方面，藉由分析粉體氧化及褐變方面數值，探討鐵劑、添加物與保存方法對儲存期間鐵強化乳粉穩定性，結果顯示，九個月保存期間無論保存方式如何，游離脂肪酸皆有增加之趨勢，相對於無氧保存下具穩定的TBA數值，有氧保存時則TBA值會隨時間延長而上升，不同鐵劑組別方面則以三價鐵劑乳粉組有較差的脂質安定性。此外，褐變性、水分及水活性在有氧保存下且含鐵劑之組別，都有顯著性的變化。以掃描式電子顯微鏡觀察三價鐵劑乳粉組發現有較大量的多孔性結構。綜合以上結果，三價鐵劑強化乳粉在粉體穩定性上有較差的保存性，但可以藉由無氧包裝之方法來改善，此試驗結果亦提供鐵質強化乳粉在開發時，如何兼具保存時粉體品質與鐵質利用性之參考依據。
The first purpose of this research was to discuss commercial milk powder which was fortified with different iron source effecting its in vitro biovailability by milk fat levels, functional food ingredients of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and vitamin E. There were 0.3, 1.5, and 3.5% of milk fat content in test samples, which were fortified with ferrous sulfate (FS), ferric chloride (FC), and of 1/2 of each (MIX), respectively. Afterward the iron bioavailability was estimated by dialyzable ferrous iron (DFe (II)), total dialyzable iron (DTFe), nondialyzable ferrous iron (NDFe (II)) and total ferrous iron (DFe(II) + NDF(II)) during enzyme hydrolysis (pepsin, pancreatin-bile salt) and dialysis. The results showed that the order of iron bioavailability among iron compounds was FS, MIX, and FC. Furthermore, the 3.5% fat level has the best efficiency in iron bioavailability among fat levels treatments. In functional food Ingredients experients, EPA can improve iron bioavailability in all iron fortified milk samples. In addition, much storage time elonge, more increment iron bioavailability of powders were found, especially in stability of ferrous iron(DFeII and DFeII+NDFeII value).To well-documented stability studies on iron-fortified food are limited due to the complexity of ingredients and processing methods. Here, we also performed a comprehensive stability evaluation on iron-fortified milk powder with various iron contents and packaging methods. Free fatty acid increased gradually over a 9 month storage period in both iron-fortified and non iron-fortified formulas, regardless of the packaging methods. Thiobarbituric acid (TBA) level remained stable in anaerobic packaging condition but increased in aerobic condition. Lipid oxidation was highest in Fe(III)-fortified formula. We showed significant increment of browning reactions, moisture and water activities in aerobic condition, especially in iron-fortified formulas, while no significant changes in anaerobic-packaged formulas. Scanning electron microscopy (SEM) showed highest porosity in Fe(III)-fortified formula. Our results showed Fe(III)-fortified formula has the lowest stability in aerobic condition but its stability improved significantly with vacuum/anaerobic packaging. Thus, our studies contribute to understanding and improving the processing and quality of iron-fortified food. |
