Kimaryo V M, Massawe G A, Olasupo N A, Holzapfel W H
Tanzania Industrial Research and Development Organization, Dar-es-Salaam.
Int J Food Microbiol. 2000 Jun 1;56(2-3):179-90. doi: 10.1016/s0168-1605(00)00159-8.
Three cassava fermentation methods (spontaneous fermentation, back-slopping and the use of starter culture) for the production of kivunde, executed in three trials at 30 degrees C, were compared in terms of cyanide level reduction, microbiology and product quality improvement. Among the isolates from spontaneously fermented cassava batches, four strains were selected on the basis of their enzymatic activities and acid production. All were identified as Lactobacillus plantarum and were used as starters in this study. Lowest residual cyanide levels were detected after 120 h fermentation time in samples fermented with the starter culture and were below the maximum value of 10 mg/kg recommended by the Codex/FAO for cassava flour. This finding seems to be related to the alpha-glucosidase activity of the inoculated strains of which API-zyme (Bio-Merieux) tests showed activities of between 20 and > or = 40 nmol/4 h. The total residual cyanide levels of the spontaneous and back-slopping fermentations at 96 h were respectively 43.5 and 47.7 mg/kg dry weight of cassava. Extension of the fermentation period to 5 days, lead to further substantial reduction in the residual cyanide level in both these processes, but not below the recommended maximum value as in the case of starter culture fermented products. The spontaneous and back-slopping fermented cassava showed signs of deterioration after 3 days of fermentation. There was a sharp drop of pH and an increase of titratable acidity for all three batches during the first 48 h followed by a slow rise of pH and drop in titratable acidity towards the end of fermentation. The samples fermented with the starter culture had a smooth texture and pleasant fruity aroma, as opposed to the course and dull appearance and more complex flavour of the samples of spontaneous and back-slopping batches. During fermentation with starter culture, Enterobacteriaceae and yeasts and moulds could not be isolated throughout the period of fermentation (detection limit: 10 colony forming units/g). The present findings indicate the suitability of these Lb. plantarum strains as starter cultures for cassava fermentation in the kivunde process. The paper highlights the potential for the improvement of a traditional African fermented food (kivunde) through the use of a starter culture.
在30摄氏度下进行了三次试验，比较了三种用于生产基文德（kivunde）的木薯发酵方法（自然发酵、回接发酵和使用发酵剂）在降低氰化物水平、微生物学和改善产品质量方面的效果。在自然发酵的木薯批次中分离出的菌株中，根据其酶活性和产酸情况选择了四株。所有菌株均被鉴定为植物乳杆菌，并在本研究中用作发酵剂。在用发酵剂发酵的样品中，发酵120小时后检测到的残留氰化物水平最低，且低于食品法典委员会/粮农组织为木薯粉推荐的10毫克/千克的最大值。这一发现似乎与接种菌株的α-葡萄糖苷酶活性有关，API-酶（生物梅里埃公司）测试显示其活性在20至≥40纳摩尔/4小时之间。自然发酵和回接发酵在96小时时的总残留氰化物水平分别为43.5和47.7毫克/千克木薯干重。将发酵期延长至5天，导致这两个过程中的残留氰化物水平进一步大幅降低，但不像使用发酵剂发酵的产品那样低于推荐的最大值。自然发酵和回接发酵的木薯在发酵3天后出现变质迹象。在最初的48小时内，所有三个批次的pH值急剧下降，可滴定酸度增加，随后在发酵结束时pH值缓慢上升，可滴定酸度下降。与自然发酵和回接发酵批次的粗糙、暗淡外观以及更复杂的风味相反，用发酵剂发酵的样品质地光滑，具有宜人的果香。在用发酵剂发酵的过程中，在整个发酵期间均未分离到肠杆菌科以及酵母和霉菌（检测限：10菌落形成单位/克）。目前的研究结果表明这些植物乳杆菌菌株适合作为基文德生产过程中木薯发酵的发酵剂。本文强调了通过使用发酵剂来改善传统非洲发酵食品（基文德）的潜力。
