以固態發酵開發機能性臺灣藜產品

Abstract

臺灣藜 (Chenopodium formosanum) 為臺灣假穀類原生種植物，其高營養價值及生物活性成分於健康之效益已被證實，具用於加工生產機能性食品之潛力。本研究以臺灣藜作為固態發酵原料，透過比較不同基質、接種之絲狀真菌及培養時間建立發酵製程，以抗氧化活性為目標最適化後進行機能性、營養性及質地等多項分析。實驗結果選定Rhizopus microsporus var. oligosporus BCRC 31996作為發酵株菌，以121oC處理之脫殼穀粒作為基質，抗氧化能力評估結果配合外觀質地觀察並比較文獻後訂立發酵時間為四日。透過反應曲面法 (Response surface methodology, RSM) 優化，於最適培養溫度35.3oC、添加碳源濃度1.31%及無機鹽濃度0.3%，可得最佳TEAC (trolox equivalent antioxidant capacity) 值20.58 mM。最適化產物之總多酚與總類黃酮含量分別為7.42 GAE mg/g dm、2.28 QE mg/g dm，與發酵前穀粒相比分別增加約2及1.8倍含量。γ-胺基丁酸 (GABA) 增加至283.57 µg/g，與最適化前相比增加5.8倍。營養特性部分，游離胜肽提升至46.18 mg/g，植酸含量下降至1.47 mg/g，降低44%含量。質地分析結果中，以臺灣藜為發酵基質相較於國外三種藜麥者，具最低硬度。經本研究建立之臺灣藜發酵模型產物具成為機能性食品之潛力。

Djulis (Chenopodium formosanum) is a native pseudocereal plant in Taiwan. Djulis has shown its potential to be processed to functional food due to its high nutritional value and the proved health benefits of its bioactive compounds. In this study, Djulis grains were used as a raw material for solid-state fermentation. The fermentation process was established by comparing different substrates, filamentous fungi and culture time. The antioxidant activity was optimized and the product was analyzed for functional and nutritional properties as well as texture. In result, Rhizopus microsporus var. oligosporus BCRC 31996 was chosen as a culture starter and dehulled grains with pretreatment of 121oC as matrix. Due to the results of antioxidant capacity evaluation, the appearance and texture observation, the fermentation time was set to four days. Optimized by Response Surface Methodology (RSM), the optimum TEAC (trolox equivalent antioxidant capacity) value was 20.58 mM at an optimum culture temperature of 35.3 oC, carbon source concentration of 1.31%, and inorganic salt concentration of 0.3%. The total phenolics and total flavonoid content of the optimized product were 7.42 GAE mg/g dm and 2.28 QE mg/g dm, respectively, which increased by about 2 and 1.8 times. γ-Aminobutyric acid (GABA) increased to 283.57 µg/g, which elevated by 5.8 times, compared to non-optimized product. In the nutritional properties, the free peptide was increased to 46.18 mg/g, and the phytic acid content was decreased to 1.47 mg/g, which decreased by 44%. In the results of texture analysis, the product using Djulis grains as the fermentation substrate had the lowest hardness compared to three kinds of foreign quinoa grains. The Djulis-fermented product established by this study demonstrated the potential to become a functional food.