Upgrading Of Traditional Technology And Use Of Starter Cultures

Several studies have been carried out to upgrade and mechanize some of the unit operations involved in the production of kenkey, including the development of shelf-stable dehydrated fermented maize meal flour as a convenience intermediary product. As mentioned above, a partly updated traditional production site is shown in Fig. 3.

Spontaneously fermented maize dough has been successfully dehydrated in a hot air tray dryer (Fig. 4) at temperatures of 60 °C, 120 °C, and 200 °C to produce acceptable

Figure 4 A hot air dryer for dehydration of fermented maize dough. (CSIR—Food Research Institute, Accra, Ghana.)

product (38). Dehydration at a temperature range of 60-70 °C did not affect total acid content of the product, and taste panel evaluations found products such as akasa, koko, and banku made from the dehydrated dough acceptable. Dehydrated fermented maize meal made by this method can be reconstituted into fresh dough by adding water and is now produced on commercial basis for sale in Ghana and also for export.

An accelerated option for industrial production of kenkey flour was developed by inoculating dry-milled maize flour with dough containing an enrichment of lactic acid bacteria to accomplish fermentation within 24 hr of incubation at 30 °C to obtain the required level of acidification (15). Subsequently, the dough was dehydrated into kenkey flour and pregelatinized aflata using cabinet and drum drying. Although the two methods were effective in preparation of pregelatinized aflata, drum drying caused a 34% reduction in titratable acidity of the fermented dough whereas cabinet drying had a less drastic effect. The possibility of using a mixture of drum-dried aflata and uncooked cabinet dried flour for convenient preparation of kenkey at domestic level was demonstrated. However, dry-milled maize flour had inferior pasting and setback viscosities as compared to the traditionally prepared dough and was not suitable for the production of pregelatinized aflata. The study concluded that even though dry-milling and accelerated fermentation of dough could drastically reduce kenkey production time from 6 days to within 24 hr, without steeping a product of inferior texture is obtained.

Another option for the industrial manufacture of kenkey in sausage casings, which takes approximately 24 hr, has also been developed (39). This method involves precracking the kernels to reduce hydration time of maize from 48 to 10 hr, incorporating aflata into the dumpling prior to fermentation to reduce fermentation time to 12 hr, and the use of a starter dough. The cooking time and energy expenditure was reduced from 2 hr to 35 min by changing the dimensions of the kenkey balls from 10-15 cm diameter to 6 cm diameter cylinders. Due to the different processing conditions, yeasts were found to be more active than in traditional fermentation, resulting in higher alcohol levels. However, these alcohol levels remained low and ethanol disappeared after cooking. The combination of lactic acid fermentation and cooking resulted in a microbiologically stable product even after the dumpling had been deliberately contaminated.

This study concluded that the traditional kenkey-making process could be shortened to 24 hr by a combination of reduced steeping time, use of starter dough in a dough-aflata mixture, and packaging in sausage casings. However, it should be noted that the traditional packaging of kenkey in maize husks or plantain leaves gives it a unique sensory characteristic that consumers associate with the product.

Attempts have also been made to increase the protein content of kenkey by fortification of the dough with amino acids, soybeans (40,41), cowpeas (42) and also by the development of Quality Protein Maize (QPM) varieties (4,5). In addition to increasing the protein content, addition of boiled whole soybeans to soaked maize before milling and fermentation reduced the fermentation time by 60% (41).

A lactic acid bacteria-enriched starter dough has been developed by back-slopping. Initially, a previous batch of acceptable-quality spontaneously fermented dough was used to inoculate fresh dough at a level of 10%. The procedure was repeated every 24 hr at 30°C until a stable culture indicated by pH, titratable acidity, and viable microbial numbers was obtained. This was then used successfully to ferment dough within 24 hr at 30°C to the required level of acidification, a total titratable acidity value of 1.24%, calculated as lactic acid on a wet-weight basis, and a pH of 3.79 (42).

A starter culture containing strains of L. fermentum, S. cerevisiae, and C. krusei has also been developed for the production of fermented maize dough. Both in laboratory trials and at a commercial production site, the period of fermentation could be reduced from 48-72 hr to 24 hr. The organoloeptic qualities of the kenkey and koko prepared from doughs fermented with the starter for 48 hr were not significantly differnt from the traditional products. However, kenkey prepared from doughs fermented for 24 hr with starter culture were found to be unacceptable by the taste panel although similarly produced koko was acceptable (43-45).

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