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  • 學位論文

數種加工方式對苦與甜樹薯理化性質影響之研究

A Study of Effects of Several Processing Methods on the Physicochemical Properties of Bitter and Sweet Cassava Genotypes

指導教授 : 林貞信 博士 邱亞伯 博士
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摘要


樹薯(Manihot esculenta Cranz),源自南美洲,數千年前被引進到非洲。估計其世界生產量在195百萬噸左右,非洲生產(103百萬噸)比世界其他各地總合還多。它是熱帶地區至少600百萬人的主食,在非洲,它為第三重要食物來源,次於米與玉米,全球產量排名第十。樹薯的澱粉含量超過80%,但蛋白質、油脂及其他礦物質則不多。樹薯的食用受限於其中高氰配糖體的含量,氰配糖體是一種化學的複合物,發現在樹薯的所有部分中,當連續食用時可能會對人體造成健康上的危害。樹薯產品像是細粉與Garri是藉由不同之加工方法(乾燥、發酵、水煮、浸漬、烘烤等)所生產的,其中某些方法被發現不足以消除或減少氰化合物到可以接受的程度。目前的研究在探討發酵(自然與人工三天)、太陽乾燥(三天)、烘箱乾燥(40與60℃下6, 12與24小時)與擠壓蒸煮(乾式與濕式)對苦及甜樹薯理化性質的影響。本研究的結果顯示,與太陽乾燥、烘箱乾燥與擠壓蒸煮來比較,發酵是最有效減少氰化物到安全程度的方法。以苦及甜兩種樹薯製作之發酵細粉、Garri與太陽乾燥或烘箱乾燥之樹薯細粉間,其氰化物殘留有顯著地(p < 0.05)差異。自然發酵有效地將新鮮樹薯中的氰化物61.67 (mg HCN equivalent/kg dry weight)分別減少至細粉的1.60與Garri的0.60 (mg HCN equivalent/kg dry weight)。自然發酵細粉、Garri、Saccharomyces cerevisae發酵細粉都顯著地(p < 0.05)低於太陽或烘箱乾燥細粉,但彼此間無顯著地(p < 0.05)差異。與同樣顯著地(p < 0.05)低於太陽(28.60 mg HCN equivalent/kg dry weight)或烘箱(27.70 mg HCN equivalent/kg dry weight)乾燥細粉的Saccharomyces cerevisae發酵細粉並無顯著地(p < 0.05)差異。濕式與乾式擠壓蒸煮都會影響苦與甜樹薯中氰化物的減少,他們彼此間顯著地(p < 0.05)不同。乾式擠壓顯著地減少苦(26.10 mg HCN equivalent/kg dry weight)與甜(9.89 mg HCN equivalent/kg dry weight)樹薯中氰化物含量,此下降的程度可以和發酵細粉相比較的。初步地,當樹薯細粉被烘箱乾燥然後乾式擠壓,在產品中會產生丙烯醯胺,其含量在4.8~14.3 ppm範圍之間。

關鍵字

氰化物 氰酸醣苷 發酵 細粉 Garri 擠壓 丙烯醯胺

並列摘要


Cassava (Manihot esculenta Cranz), originated from South America, was introduced into Africa thousands of years ago. The world production is estimated at around 195 million tones. Production from Africa (103 million tones) is more than the rest of the world combined. It is a staple food for at least 600 million people in the tropics. In Africa, it is the third most important food source after rice and maize and ranked tenth in terms of production world wide. The starch content of cassava is more than 80% but low in protein, fat and other minerals. Consumption of cassava is limited due to its high content of cyanogenic glucosides, a chemical compound that can be found in all parts of cassava and has potentials to pose health risks to human beings when continuously consumed. Cassava products such as flour and Garri are produced by application of different processing methods (drying, fermentation, boiling, soaking, roasting etc.) and some of these methods are found to be inefficient in eliminating or reducing cyanide compound to acceptable levels. The present study investigated the effects of fermentation (natural and induced for 3 days), sun drying (3 days), oven drying 40 and 60ºC for 6, 12, and 24 hours), and extrusion cooking (dry and wet) on the physicochemical properties of bitter and sweet cassava genotypes. Results of this study showed that fermentation was the most effective method of reducing cyanide to safe levels compared to sun drying, oven drying, and extrusion cooking. There was significant difference (p<0.05) on residual cyanide among fermented cassava flours, Garri and sun-dried or oven-dried flours of both bitter and sweet varieties. The cyanide levels in natural fermented flour and Garri were found 1.60 and 0.80 mg equivalent/kg dry weight from the initial cyanide content of 61.67 HCN mg/kg equivalent dry weights in fresh cassava pulp, respectively. Natural fermented flour, Garri, and Saccharomyces cerevisae fermented flour were significantly (p<0.05) lower than the sun-dried (28.60 mg HCN equivalent/kg dry weight) or oven-dried (27.70 mg HCN equivalent/kg dry weight flours, but were not significantly (p>0.05) different from each other. Wet and dry extrusion cooking had also effected cyanide reduction in both bitter and sweet cassava genotypes and they were significantly (p<0.05) different from each other. Dry extrusion had a significant cyanide reduction in both bitter (26.10 mg HCN equivalent/kg dry weight), and sweet (9.89 mg equivalent/kg dry weight) cassava extrudate and the level of reduction was comparable to the fermented flours. Preliminary study on acrylamide confirmed that it could be formed when cassava was oven-dried and then dry extruded, although the quantities were insignificant and ranged from 4.8 to 14.3 ppm.

並列關鍵字

cyanide cyanogenic glucoside fermentation flour Garri extrusion acrylamide

參考文獻


Biedermann, M., A., Noti, Biedermann-Brem and K. Grob (2002). Methods for determining the potential of acrylamide formation and its elimination in raw materials for food preparation, such as potatoes. Mitteilungen aus Lebensmitteluntersuchung und Hygiene (93), 653-667.
Achi, O.K. and N.S. Akomas (2006). Comparative assessment of fermentation techniques in the processing of Fufu, a traditional fermented cassava product. Pakistan Journal of Nutrition (5), 224-229.
Akintonwa, A., O.O. Tunwashe and A.A. Onifade (1994). Fatal and non-fatal acute poisoning attributed to cassava-based meal. Acta Horti-cullturae (375), 285-288.
Aletor, V.A. (1993). Cyanide in Garri: Assessment of some aspects of the nutrition, biochemistry and hematology of the rats fed Garri containing varying residual cyanide levels, International Journal of Food Science and Nutrition (44), 289-292.
Alonso, R., E. Orue, M.J. Zabalaza, G. Grant and F. Marzo (2000). Effects of extrusion cooking on the structure and functional properties of pea and kidney bean proteins. Journal Science Food Agriculture (80), 397-403.

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