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|標題:||Quality Evaluation of Anka Bread and Its Antioxidant Properties
|關鍵字:||紅麴土司;Anka bread;品質評估;抗氧化性質;機能性成分;quality evaluation;antioxidant properties;functional components||出版社:||食品科學系||摘要:||
在25°C的儲藏條件下，當儲藏到第六天時，在總生菌數上紅麴土司（5.74）明顯低於白土司（6.58）及米土司（6.12 log CFU/ml），顯示紅麴具有不錯的抑菌效果。而三種土司在質地剖析（TPA）方面，隨著儲藏天數的增加，硬度及破碎度皆有增加的趨勢，附著性、彈性、凝聚性、膠性度及咀嚼度則隨著儲藏天數的增加而降低，其中紅麴土司在凝聚度及咀嚼度的下降趨勢則比其餘兩種土司較為緩慢。同時以掃描式電子顯微鏡（SEM）觀察發現，三種土司隨著儲藏天數的增加，其網狀結構逐漸緊密、平滑，此些皆為澱粉回凝所致。
紅麴土司的呈味品質分析包含可溶性糖、游離胺基酸及核苷酸含量。在可溶性糖的部分，紅麴土司具有較高的甘露糖醇（1.38 mg/g）及核糖（2.63 mg/g）；在游離胺基酸總含量方面，紅麴土司（3.51 mg/g）高於白土司（2.78 mg/g）及白米土司（3.17 mg/g）；而核苷酸的含量則依序為紅麴土司（52.86 μg/g）>白土司（43.54 μg/g）>米土司（23.48 μg/g）。整體而言，紅麴的添加可以提高土司的鮮味及甜味，同時賦予土司較高的營養價值。
三種土司經乙醇萃取後，所得之乙醇萃經進行其抗氧化性質分析。結果顯示，在抗氧化力的部分，三種土司之乙醇萃的抗氧化力隨著濃度的增加卻有逐漸下降的趨勢；紅麴土司乙醇萃之還原力在10.0 mg/ml時為0.66，高於白土司乙醇萃的0.14及米土司乙醇萃的0.17；在清除1,1-二苯基-2-苦味肼基團的能力部分，在20.0 mg/ml時，紅麴土司乙醇萃最佳
在機能性成分上，紅麴土司經過高溫烤焙後，仍保有可降膽固醇的monacolin K（3.93 mg/kg）及可降血壓的γ-胺基丁酸（53.12 mg/kg）。在消費者喜好性分析方面，紅麴土司在色澤、風味、外觀及總體喜好性之數值上較白土司及米土司略高，尤其在口感的接受度上，以紅麴土司（5.70）最佳，米土司（5.45）次之，而白土司（5.31）最低。
Monascus produces various metabolites beneficial for humans, which exhibit cholesterol-lowering, blood pressure-lowering, antimicrobial and antioxidant properties. In order to improve the healthy efficacy of baked foods, the study reported herein is to inoculate the Monascus purpureus culture to cooked refined rice and anka thus produced was added in a amount of 3% to mix with flour to make bread, and the anka bread thus obtained was analyzed for its storage properties, taste quality, antioxidant properties and functional components and evaluated for its sensory quality.
During storage at 25°C, total plate counts of anka bread (5.74) was significantly lower than those of white bread (6.58) and rice bread (6.12 log CFU/ml) at day 6, indicating the good antimicrobial activity of anka. Based on the texture profile analysis (TPA), the hardness and fracturability of three breads increased with storage time prolonged whereas the adhesiveness, springiness, cohesiveness, gumminess and chewiness decreased. However, the decreased rate in adhesiveness and chewiness was slower for anka bread than for other breads. In addition, as shown in scanning electron micrographs, the structure of three kinds of breads was denser as storage time prolonged as the consequence of staling.
The taste components of anka bread included soluble sugars, free amino acids and flavor 5'-nucleotides. In the composition of soluble sugars and polyols, anka bread contained higher contents of mannitol (1.38 mg/g) and ribose (2.63 mg/g). Anka bread contained more total free amino acids (3.51 mg/g) than white bread (2.78 mg/g) and rice bread (3.17 mg/g). The contents of 5'-nucleotides for three breads were in order of anka bread (52.86 μg/g) > white
bread (43.54 μg/g) > rice bread (23.48 μg/g). Overall, the addition of anka could enhance palatable taste and sweet taste of bread and also impart with more nutritional values.
The ethanolic extracts were analyzed for their antioxidant properties after extraction of three kinds of breads. The antioxidant activities of ethanolic extracts decreased with the increased concentrations. The reducing power of ethanolic extract from anka bread (0.66) was better than those of ethanolic extracts from white bread and rice bread (0.14 and 0.17) at 10.0 mg/ml.
The scavenging ability of ethanolic extracts from anka bread (89.63%) on 1,1-diphenyl-2-picrylhydrazyl radicals was best at 20.0 mg/ml, significantly higher than those of ethanolic extracts from white bread and rice bread (58.84 and 55.73%). The chelating abilities of ethanolic extracts from three breads were not good.
With regard to functional components, final baked product of anka bread contained 3.93 mg/kg of monacolin K and 53.12 mg/kg of γ-aminobutyric acid. With regard to consumer preference, the hedonic scores of color, odor, flavor and overall ratings of anka bread were slightly higher than those of white bread and rice bread. The mouth feel of three kinds of breads were in the descending order of anka bread (5.70) > rice bread (5.45) > white bread (5.31).
In conclusion, anka bread not merely contained favorable color, flavor, mouth feel and acceptability but also possessed better antioxidant properties and functional components. The research studied the quality and antioxidant properties of anka bread to provide food industry with more information to develop new functional baked products and consumers with better instruction for purchasing.
Keyword: Anka bread, quality evaluation, antioxidant properties, functional components
|Appears in Collections:||食品暨應用生物科技學系|
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