A. A. Onilude

Influence of cultural conditions on the production of bacteriocin by Lactobacillus brevis OG1

demonstrated that larger quantities of bacteriocin could be produced by addition of yeast extracts (3.0%), NaCl (1.0-2.0%), glucose (1.0 %) and Tween 80 (0.5%), while addition of tri-ammonium citrate, sodium acetate, magnesium sulphate, manganese sulphate and potassium phosphate had no effect on production. Maximal activity in composed medium was achieved at initial pH of 5.5, and incubation period of 48h at 30-37 0 C.

Assessment of microbiological quality of sachet-packaged drinking water in Western Nigeria and its public health significance

OBJECTIVE To assess the microbiological quality of sachet-packaged drinking water in Western Nigeria and its impact on public health. STUDY DESIGN Cross-sectional microbiological testing. METHODS Ninety-two sachet-packaged water samples were analysed for microbiological and metal qualities. Total bacterial and coliform counts were determined, and the presence of Escherichia coli, an important water quality indicator, was tested. The level of conformity of the water processors with the guidelines of Nigerias quality regulatory agency was also determined. RESULTS Varying levels of microbial contamination were recorded in samples from the different sampling locations. The total bacteria count ranged between 2.86 and 3.45log colony-forming units (cfu)/ml. The highest coliform count recorded was 1.62log cfu/ml. Faecal coliform E. coli was detected in one sample from Oke-Iho and one sample from Okaka, representing 2.2% of total samples. Lead and manganese were not found in any of the samples. However, iron was detected and the highest iron concentration (0.10mg/l) was detected in samples from Ikorodu. The bacteria that were identified from the water samples included E. coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Klebsiella sp., Proteus vulgaris, Alcaligenes faecalis, Bacillus cereus, Staphylococcus aureus, Streptococcus lactis, Aeromonas sp. and Micrococcus luteum. Many of the water processors did not comply with the guidelines of the quality regulatory agency. CONCLUSIONS Some of the sachet-packaged samples of drinking water were of poor quality. The results indicate a need for Nigerias quality regulatory agency to take appropriate measures in safeguarding public health.

Microbial deterioration of traditional alcoholic beverages in Nigeria

Abstract A study was carried out to investigate the microbiological quality and physico-chemical changes of “aged’’ cereal-based traditional alcoholic beverages in Nigeria. There were variations in the microorganisms isolated from sekete, pito and burukutu at post-production time of 72 h, but Saccharomyces cerevisiae, Acetobacter aceti, A. hansenii, A. pasteurianus, Alcaligenes, Flavobacterium, Lactobacillus plantarum and L. brevis were common to all samples. A vinegary flavour and off-odour were the pronounced characteristics of the deteriorating beverages. The decrease in the ethanol from 3% in the fresh product to 1% at the end of 72 h retailing period is proportional to the acetic acid content of the drinks. However, slight decreases were observed for lactic, malic, succinic and formic acid constituents of the beverages. Although no enterobacteriaceae was isolated, some of the identified isolates are potentially pathogenic, and can become injurious to the health of the consumers of “aged’’ batches of the beverages.

Effect of process improvement on the physico-chemical properties of infant weaning food from fermented composite blends of cereal and soybeans

Saccharomyces cerevisiae and Lactobacillusplantarum ATCC 10776 were used as starters toferment various composite blends of cereals and legumes produced through malting and toasting of two varieties of maize – Zea mays (DMR-LSR white & DMR-ESR yellow),sorghum – Sorghum bicolor (Dawa white & Dawared) and one variety of soybeans (Glycine max). Compared to the untoasted and unmaltedfermented blends, a relatively lower pH (3.6),highly sour product was obtained with 12 h offermentation. Results also showed that cereal and soybeantoasting brought about a better reconstitution indices(B25, 84 ml; B45, 87 ml), water holding capacities(B25, 0.68 ml/g; B45, 0.62 ml/g), bulk densities (C15,11.6; C35, 10.8) and gross energy (B15, 501.5Kcal/100g; B45, 508.5 kcal/100g) at the end offermentation. Furthermore, reductions in totalpolyphenol and tannin contents were observedwith fermentation of toasted and malted cereal blendssupplemented with toasted and malted soybeans whileporridges from the same blends displayed desirablestarch stability and consistent gelling tendency,although B15 (a ferment of malted, toasted white maizesupplemented with toasted and malted soybean) fellwithin acceptable limits. In all, the physicalcharacteristics were affected by varieties of cerealand soybeans.

Production of sour maize bread using starter-cultures

Eight lactic acid bacteria were isolated from fermenting maize meal. They were identified as Lactobacillus brevis, L. casei, L. fermentum, Pediococcus acidilacti, P. pentosaceus, Lactobacillus spp. I and Pediococcus spp. I and II. L. brevis and Lactobacillus spp. I isolated from the spontaneously fermented maize meal together with L. brevis isolated from rye sour dough and L. plantarum from ogi, a fermented maize gruel, were selected as starter organisms. There was a decrease in the final pH from 4.9 to 3.8 and an increase in the acid equivalent and temperature of the spontaneously-generated sour maize meal at the end of 24h fermentation. There was a decrease in the pH and moisture content of the sour maize breads relative to the conventional wheat bread. An improvement in the shelf-life of the bread samples was also obtained. Crude protein values of the sour maize breads were between 4.36% and 8.87%, while crude fat contents ranged between 3.66% to 7.67%. The ash contents increased from 2.29% to 2.54% while total carbohydrate values were between 46.31% and 65.3%. Calcium, phosphorus and potassium contents ranged from 0.015, 0.26 and 0.018% to 0.036, 0.47 and 0.036% respectively. Physical examination of the bread samples showed that all were cracked and relatively hard. Weight, height and volume ranged from 316 to 380g; 4.2 to 5.2cm and 200 to 320cm3 respectively. Statistical analysis of the sensory attributes revealed a consumer acceptance of the sour maize breads, although ranking test showed preference for the bakers yeast leavened bread that served as a control.

Influence of lactic cultures on the quality attributes of tsire, a West African stick meat

Tsire is a popular, traditionally processed West African stick meat. Two lactic acid bacteria (LAB), Pediococcus acidi-lactici and Lactobacillus plantarum were used to inoculate pieces of fresh beef before (TA) and after (TB) grilling followed by incubation at 30 °C for 24 h. TA and TB tsire samples had the lowest coliform count (expressed as log c.f.u./g) of 13.48 and 8.83, Staphylococcus count of 7.90 and 5.76, Pseudomonas count of 10.06 and 5.99 on day 6 of storage period respectively. There was an increase in the population of the inoculated LAB in the TA and TB samples to 10.93 and 12.41 respectively. However, the uninoculated samples (TU) had a relatively high coliform, Staphylococcus and Pseudomonas counts. Biochemical analysis of the tsire products showed the TB samples having the highest crude protein (26.43%), thiobarbituric acid (0.25 mg malonaldehyde/kg) and free fatty acid (0.45 mg KOH/g lipid) values. Polyvinyl chloride was found to be the most suitable packaging material for the products during storage, compared with aluminium foil and newsprint. Organoleptic evaluation of the tsire samples also revealed that the TB samples were rated higher in terms of texture, appearance and flavour, while the uninoculated samples had the lowest scores.

Effect of fungal enzyme mixture supplementation of various fibre-containing diets fed to broiler chicks 1: Performance and carcass characteristics

Partially purified enzymes: amylase of Macrophomina phaseolina, cellulase of Trichoderma sp. and pectinase of Fusarium trincitum were produced, purified and mixed together to form a three-enzyme system. A similar mixture was produced for the crude forms of the three enzymes. The two forms of the enzyme mixture were then applied to diets containing wheat bran, rice bran, palm kernel meal, corn bran or coconut meal and were fed to 784 1-day-old broiler chicks of both sexes. Results after six weeks showed the live weight, the body weight gain and the feed conversion ratio to be significantly affected by enzyme supplementation for all fibre types included in the diets. Over the feeding interval, the plucked weight, carcass weight, edible meat and the total bone weight also increased in amount for both crude and partially purified forms of the enzyme applied directly or in water, compared with the unsupplemented diet. Statistically significant differences P(0.05) also existed in the percentage protein and ash content of the carcass of both the unsupplemented and supplemented diets.

Effect of fungal enzyme mixture supplementation of various fibre-containing diets fed to broiler chicks 2: On blood, liver and kidney total lipids, triacylglycerols and cholesterol

Broiler chicks of both sexes were fed formulated rations containing different fibre types with and without supplementation with crude and pure microbial enzymes in order to determine the effect on the lipids of the blood, liver and kidney. Results shown enzyme supplementation to greatly and significantly affect total lipid, free fatty acids, triglyceride and cholesterol levels of the blood, liver and kidney relative to the age of the birds and the type of fibres. By day 42, the total blood lipid of the unsupplemented diet rose to the highest level (22.4 mg/l), that of the kidney (3.62 mg/g) and the liver (185.7 mg/g). Enzyme supplementation, however, brought about reduction of these values with the diet containing all the fibres – wheat bran, corn bran, palm kernel meal and coconut meal giving the lowest values of the total lipids, free fatty acids, triglycerides and cholesterol on day 42 for the blood, liver and kidney, respectively. The pure forms of the enzymes applied directly to the feed gave more highly significant effects than the crude forms fed through water. Interaction effects between the various forms of the enzyme and the mode of application were also statistically significant.

Production, purification and characterisation of a β- mannanase by Aspergillus niger through solid state fermentation (SSF) of Gmelina arborea shavings

Mannanase production by a wild-type Aspergillus niger, isolated from spontaneously-degrading wood from South Western Nigeria was monitored at three day intervals for a period of 15 days in media containing pretreated wood shavings of Anogeissus leiocarpus, Gmelina arborea and Terminalia superba as carbon sources. Highest mannanase activity of 25.938 U/g of dry wood shavings was obtained on the 9 th day in a medium containing G. arborea as sole carbon source. Maximum activity value for the medium containing A. leiocarpus was 14.110 U/g obtained on the 9th day. On the medium containing T. superba, a maximum activity value of 10.148 U/g was obtained on the 12th day of incubation. G. arborea substrate gave the highest total protein yield of 18.146 mg/ml and the specific mannanase activity of 1.201 U/mg on the crude enzyme extracts. A mannanase activity of 19.091 U/mg was subsequently achieved after purification on ion exchange chromatography with a purification fold of 15.894. Enzyme activities were at their peaks at pH 5.5 (0.4331 U/ml) and at temperature 30°C (1.8617 U/ml). A Km value of 0.754 mg/ml and Vmax value of 1.364 U/mg/min was achieved for the enzyme which was thermally stable up to 65°C. G. arborea wood shavings hold tremendous potential in mannanase production for several industrial uses by the fungus.

Fermented poultry litter and fungal enzyme supplementation of high-fibre broiler diets: Growth responses, carcass characteristics and blood lipids of fed chicks

Three different types of poultry litter, Broilers (BL), Layers (LL) and Growers (GL), were subjected to fermentation by a mixed starter culture of Aspergillus niger, Leuconostoc spp. and Candida utilis for 108 h. Fermentation resulted in increase of crude protein, nitrogen free extract, calcium, phosphorus, biomass and amino acid content. The dried, highly fermented broilers litter was applied at 2 levels (0, 15%; w/w) as supplement of high-fibre basal diet along with different levels of fungal enzyme mixture (0, 1, 5, 10, 20 and 25 IU/kg diet) fed to 480 day-old broiler chicks of mixed sex in 2 trials conducted to study the growth responses and blood lipid composition of such birds to the diets. Results of these trials show a positive correlation between enzyme supplementation and body weight, feed efficiency, carcass weight, edible meat and the meat: bone ratio. Consistently significant reduction was observed in the blood total lipid, free fatty acid, phospholipid and cholesterol concentrations between the enzyme-deficient diet and the enzyme- and fermented poultry litter supplemented diet. However, from both trials it is concluded that an enzyme concentration of 15 IU/kg diet in the presence of 15% fermented poultry litter is best for supplementation.