Quality Evaluation of Anka Bread and Its Antioxidant Properties

• Main Authors: Chi-Hsin Chen, 陳祺欣
• Other Authors: Jeng-Leun Mau
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/64196936914781448518

碩士 === 國立中興大學 === 食品科學系 === 93 === Abstract 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