Journal of Food Technology in Africa

The Effects of Technological Modifications on the Fermentation of Borde, an Ethiopian Traditional Fermented Cereal Beverage

Kebede Abegaz — 2004-06-28

Four independent experiments were carried out to study the effect of modifying some steps in the technology of the four-phase traditional borde fermentation using malt and a mixture of unmalted cereals. When maize flour was substituted for maize grits in Phase I fermentation, the titratable acidity was greater throughout this phase and decreased after 24 h. Substitution with flour resulted in a higher yield, improved acceptability and extended keeping quality of borde. In addition, the wet milling at the last stage of the process could be omitted. When Phase I was omitted from the process, the starting pH at Phase II was much higher than when fermented maize from Phase I was used. Although the pH by the end of Phase II was comparable in both treatments, the borde made using fermented maize from Phase I was superior in all sensory attributes. Unmalted ingredients were heat treated in various ways and all methods were found to produce acceptable borde. However, borde from uncooked ingredients was totally unacceptable. An investigation on the effect of merging some phases of the fermentation showed that it is possible to prepare an acceptable borde using a simplified method of production. There were no marked variations in microbial load of borde from all the above treatments. It was found possible to shorten the duration and simplify the technology of borde fermentation with some variations in acceptability.

Key Words: food processing; traditional fermentation; cereal beverage, borde; Ethiopia

Journal of Food Technology in Africa Vol.9(1) 2004: 3-12

Potential African Substitutes for Hops in Tropical Beer Brewing

PE Ajebesone — 2004-06-28

The potential of four selected tropical vegetables, Grongonema latifolium (Utazi), Vernonia amigdalina (Bitter leaf), Azadirachta indica (Neem) and Garcinia cola (Bitter Kola) as substitutes for hops in tropical beer brewing were evaluated.

The vegetables were processed into powder by drying at 50°C for 24 hours (such that they maintained their original colour) and then cooled in dessicator before milling in a hammer mill. Proximate analysis showed that these vegetables had protein and crude fibre values comparable to those of commercial hops. Fat content values were however much higher than those for hops with Grongonema latifolium having the highest values of 19.10%. Garcinia cola with a total resin value of 8.24% and an essential oils value of (1.16ml/ 100g) had values which were significantly different from those of hops. The other three had values comparable to those for hops. Bitterness levels were high when the vegetables were extracted with organic solvents, than with distilled water. These values however decreased, the longer the storage period. Losses in bitterness were more when the vegetables were stored at ambient temperature than when they were stored at refrigeration or freezing temperatures. Losses in bitterness were more for water extracts than for organic solvent extracts.

Key Words: Hops, Resins, Essential Oils, Bitterness level

Journal of Food Technology in Africa Vol.9(1) 2004: 13-16

Drying Kinetics, Physico-chemical and Nutritional Characteristics of "Kindimu", a Fermented Milk-Based-Sorghum-Flour

NL Tatsadjieu — 2004-06-28

"Kindimu", a fermented milk-based cereal foods made by sun drying a mixture of fermented milk and cereal flour is a common flour ingredient in the central African region. A study was carried out to evaluate the effect of processing methods on the drying behaviour, functional and nutritional quality of such a food prepared from sorghum flour and fermented milk. A mixture of 1 part sorghum flour (germinated or non - germinated) and the 2 part (w/w) on fermented milk was coated on aluminium trays to a depth of 5mm and dried at 50, 65 or 80°C. Results obtained indicated that a simple mass transfer equation Ln [(C-C*)/(Co-C*)]= -(K/L)t can be used to model the drying behaviour of the fermented milk -sorghum flour mixtures. The magnitude of mass transfer coefficient K, increased with drying temperature and the germination of sorghum. Germination and addition of milk increased the in vitro protein digestibility of sorghum flour by 19.03%, protein solubility by 11.5% and available lysine content by an average of 3.04% and reduced the phytate content by 30%. The water absorption capacity of flours was equally reduced by an average of 4%.

Key Words: Fermented milk, sorghum, malting, drying kinetic, physico-chemical properties, nutritional properties.

Journal of Food Technology in Africa Vol.9(1) 2004: 17-22

Occurrence of Multiple Antimicrobial Resistance among Staphylococcus aureus Isolates from Kenyan Milk

Anakalo Shitandi — 2004-06-28

Two hundred and sixteen isolates of staphylococcus aureus were obtained from raw milk within different locations in the Rift Valley of Kenya. Their resistance profiles to six families of antimicrobials were evaluated using the plate diffusion method. Resistance to penicillin (72.2 %) was the most frequent followed by trimethoprim + sulfamethazin (59.2 %); tetracycline (57.9 %); erythromycin (21.3 %); chloramphenicol (46.8 %) and methicillin (7.8 %). Multiple resistances, to penicillin and at least two other non - β-lactam classes of antimicrobials, were observed in 76.9 % of isolates. Multiple resistances to more than four antimicrobials were 13.4 % while 1.9 % were susceptible (non resistant) to all six antmicrobials tested. Pearsons ÷² statistic was determined to be 10.98 and ÷² , _{6 df} = 12.59 (at P = 0.05) , under the null hypothesis of no association for the five regions and resistance pattern. It was concluded that while most of the isolates (76.9 %) were multiple resistance to the tested antimicrobials, there was independence (at the 0.05 level of significance) between the sensitivity levels evident and the regions.

Key Words: Milk; Staphylococcus aureus; Antimicrobial Resistance; Multiple resistance

Journal of Food Technology in Africa Vol.9(1) 2004: 23-25

Nutrient Content and Organoleptic Quality of Traditional African Strain and Rhode Island Chickens and the Effect of Feed Rations

Germain Kansci — 2004-06-28

Pectoral and thigh muscles of African strain and Rhode Island chickens were characterised for their contents in moisture, proteins, lipids and phospholipids. Water retention capacity of the muscles was measured and the influence of enriched cotton cake feed on the muscle quality of Rhode Island race chicken was evaluated. The chicken stocks and their muscles were similar in terms of their water contents (73.6 - 74.9 g/100g). The muscles of the both chicken stocks showed excellent water retention capacity (up to 69%). The Rhode Island race were however, richer in lipids (2.74 - 3.46 g/100g) and phospholipids (0.34 - 0.57 g/100g). Feeding with cotton cake-enriched rations increased the lipid content further. On the other hand, muscles of the African strain chicken were richer in proteins (22.5 - 24.3 g/100g) than those of the Rhode Island race (19.5 - 22.5 g/ 100g). The nutritional, organoleptic and technological qualities of the chicken muscles are discussed with respect to these characteristics. Cultural consumption habits could explain preference of African Strain Chicken muscles by the local population.

Key Words: chicken, feed, lipids, water retention capacity, proteins, quality

Journal of Food Technology in Africa Vol.9(1) 2004: 26-28

Effect of Insecticidal Plant Materials, Lantana camara L. and Tephrosia vogelii Hook, on the Quality Parameters of Stored Maize Grains

JO Ogendo — 2004-06-28

The effect of ground powders of two tropical plants, Lantana camara L. and Tephrosia vogelii Hook, on the level of insect damage and the grain quality parameters of stored maize were evaluated for five months. The evaluations were aimed at generating natural product treatments suitable for post-harvest grain protection and as sustainable alternatives to synthetic insecticides in the control of the maize weevil, Sitophilus zeamais Motschulsky. Three rates (1.0, 2.5 and 5.0% w/w) of each plant powder, a synthetic insecticide, Actellic Super 2% dust at 0.05% w/w and an untreated control were used as treatments. Results showed that the plant powders significantly minimised the magnitude of depression in percent grain moisture content albeit at a lesser rate with high concentration and had no effect on the percent germination of maize grains when compared to the controls. The botanical treatments and synthetic insecticide were equally effective in reducing insect damage by 25%, but the level of damage was independent of the concentration applied. Grain colour and odour were unaffected by the botanicals. Results are discussed with regard to the use of botanicals by small-scale farmers as cost-effective and sustainable alternatives to synthetic insecticides in maize grain storage.

Key Words: botanicals, indigenous knowledge, grain storage, grain quality parameters, synthetic insecticides, insect damage, seed viability, food safety

Journal of Food Technology in Africa Vol.9(1) 2004: 29-35