Technological properties and probiotic potential of <i>Lactobacillus fermentum</i> strains isolated from West African fermented millet dough

BACKGROUND: Throughout Africa, food fermentations are still driven by indigenous microorganisms which influence the nutritional, organoleptic and safety of the final products. However, for improved safety, consistent quality and beneficial health effects, a trend has emerged which involves the isolation of indigenous strains from traditional fermented products to be used as functional starter cultures. These functional starter cultures possess inherent functional characteristics and can contribute to food quality and safety by offering one or more organoleptic, nutritional, technological or health advantage (probiotics). With the aim of selecting potential probiotic starter cultures, Lactobacillus fermentum strains isolated from fermented millet dough were investigated for technological properties and probiotic traits in-vitro. RESULTS: A total of 176 L. fermentum strains were assessed for technological properties including rate of acidification, exopolysaccharide production and amylase activity. Following this, 48 strains showing desirable technological properties were first screened for acid resistance. Sixteen acid resistant strains were assessed for additional probiotic properties including resistance to bile salts, bile salt hydrolysis, antimicrobial property, haemolysis and antibiotics resistance. L. fermentum strains clustered into 3 groups represented by 36 %, 47 % and 17 % as fast, medium and slow acidifiers respectively. About 8 %, 78 % and 14 % of the strains showed strong, weak and no exopolysaccharides production respectively. Amylase activity was generally weak or not detected. After exposure of 48 L. fermentum strains to pH 2.5 for 4 h, 16 strains were considered to be acid resistant. All 16 strains were resistant to bile salt. Four strains demonstrated bile salt hydrolysis. Antimicrobial activity was observed towards Listeria monocytogenes and Staphylococcus aureus but not E. coli and Salmonella enteritidis. Lactobacillus fermentum strains were generally susceptible to antibiotics except 6 strains which showed resistance towards streptomycin, gentamicin and kanamycin. CONCLUSION: In vitro determination of technological and probiotic properties have shown strain specific difference among L. fermentum strains isolated from fermented millet dough. Sixteen (16) L. fermentum strains have been shown to possess desirable technological and probiotic characteristics in vitro. These strains are therefore good candidates for further studies to elucidate their full potential and possible application as novel probiotic starter cultures

Quality evaluation of processed clay soil samples

Introduction: This study assessed the microbial quality of clay samples sold on two of the major Ghanaian markets. Methods: The study was a cross-sectional assessing the evaluation of processed clay and effects it has on the nutrition of the consumers in the political capital town of Ghana. The items for the examination was processed clay soil samples. Results: Staphylococcus spp and fecal coliforms including Klebsiella, Escherichia, and Shigella and Enterobacterspp were isolated from the clay samples. Samples from the Kaneshie market in Accra recorded the highest total viable counts 6.5 Log cfu/g and Staphylococcal count 5.8 Log cfu/g. For fecal coliforms, Madina market samples had the highest count 6.5 Log cfu/g and also recorded the highest levels of yeast and mould. For Koforidua, total viable count was highest in the samples from the Zongo market 6.3 Log cfu/g. Central market samples had the highest count of fecal coliforms 4.6 Log cfu/g and yeasts and moulds 6.5 Log cfu/g. "Small"market recorded the highest staphylococcal count 6.2 Log cfu/g. The water activity of the clay samples were low, and ranged between 0.65±0.01 and 0.66±0.00 for samples collected from Koforidua and Accra respectively. Conclusion: The clay samples were found to contain Klebsiella spp. Escherichia, Enterobacter, Shigella spp. staphylococcus spp., yeast and mould. These have health implications when consumed.Pan African Medical Journal 2016; 2

The use of lactic acid bacteria starter culture in the production of<em> Nunu</em>, a spontaneously fermented milk product in Ghana

Nunu, a spontaneously fermented yoghurt-like product, is produced and consumed in parts of West Africa. A total of 373 predominant lactic acid bacteria (LAB) previously isolated and identified from Nunu product were assessed in vitro for their technological properties (acidification, exopolysaccharides production, lipolysis, proteolysis and antimicrobial activities). Following the determination of technological properties, Lactobacillus fermentum 22-16, Lactobacillus plantarum 8-2, Lactobacillus helveticus 22-7, and Leuconostoc mesenteroides 14-11 were used as single and combined starter cultures for Nunu fermentation. Starter culture fermented Nunu samples were assessed for amino acids profile and rate of acidification and were subsequently evaluated for consumer acceptability. For acidification properties, 82%, 59%, 34%, and 20% of strains belonging to Lactobacillus helveticus, L. plantarum, L. fermentum, and Leu. mesenteriodes, respectively, demonstrated fast acidification properties. High proteolytic activity (>100 to 150 μg/mL) was observed for 50% Leu. mesenteroides, 40% L. fermentum, 41% L. helveticus, 27% L. plantarum, and 10% Ent. faecium species. In starter culture fermented Nunu samples, all amino acids determined were detected in Nunu fermented with single starters of L. plantarum and L. helveticus and combined starter of L. fermntum and L. helveticus. Consumer sensory analysis showed varying degrees of acceptability for Nunu fermented with the different starter cultures

Prevalence, virulence factor genes and antibiotic resistance of<em> Bacillus cereus sensu lato </em>isolated from dairy farms and traditional dairy products

BACKGROUND: B. cereus are of particular interest in food safety and public health because of their capacity to cause food spoilage and disease through the production of various toxins. The aim of this study was to determine the prevalence, virulence factor genes and antibiotic resistance profile of B. cereus sensu lato isolated from cattle grazing soils and dairy products in Ghana. A total of 114 samples made up of 25 soil collected from cattle grazing farm land, 30 raw milk, 28 nunu (yoghurt-like product) and 31 woagashie (West African soft cheese). Ninety-six B. cereus sensu lato isolates from 54 positive samples were screened by PCR for the presence of 8 enterotoxigenic genes (hblA, hblC, hblD, nheA, nheB, nheC, cytK and entFM), and one emetic gene (ces). Phenotypic resistance to 15 antibiotics were also determined for 96 B. cereus sensu lato isolates. RESULTS: About 72% (18 of 25 soil), 47% (14 of 30 raw milk), 35% (10 of 28 nunu) and 39% (12 of 31 woagashi) were positive for B. cereus sensu lato with mean counts (log(10) cfu/g) of 4.2 ± 1.8, 3.3 ± 2.0, 1.8 ± 1.4 and 2.6 ± 1.8 respectively. The distribution of enterotoxigenic genes revealed that 13% (12/96 isolates) harboured all three gene encoding for haemolytic enterotoxin HBL complex genes (hblA, hblC and hblD), 25% (24/96 isolates) possessed no HBL gene, whereas 63% (60/96 isolates) possessed at least one of the three HBL genes. All three genes encoding for non-haemolytic enterotoxin (nheA, nheB and nheC) were detected in 60% (57/96) isolates, 14% (13/96) harboured only one gene, 19% (18/96) whereas 8% possessed none of the NHE genes. The detection rates of cytk, entFM, and ces genes were 75, 67 and 9% respectively. Bacillus cereus s. l. isolates were generally resistant to β-lactam antibiotics such as ampicillin (98%), oxacillin (92%), penicillin (100%), amoxicillin (100%), and cefepime (100%) but susceptible to other antibiotics tested. CONCLUSIONS: Bacillus cereus s. l. is prevalent in soil, raw milk and dairy products in Ghana. However, loads are at levels considered to be safe for consumption. Various enterotoxin genes associated with virulence of B. cereus are widespread among the isolates

The Physico-chemical Characteristics of Yeast Fermentation of two Mango (Mangifera indica Linn) Varieties.

Efficient methods of post harvest handling, preservation and value addition are critical for minimizing high losses in the post harvest chain of fruits.  The goal of this study was to address this problem by employing yeast fermentation technology to produce a more stable, value added product from mangoes. The design of the study involved determination of the fermentative capabilities of a selected yeast strain on the quality characteristics of mango wine obtained from two selected mango cultivars (improved and wild) with and without peels. The response variables monitored in the must and wine included total soluble solids (TSS), pH and total acidity (TA), microbial populations (aerophilic mesophiles, yeasts and Acetic acid Bacteria), and alcohol content. Volatile compounds development was also monitored using GC-FID procedures. Descriptive and hedonic sensory evaluations were carried out on the mango wine obtained from all treatments. The effects of mango peels in must fermentation characteristics compared well with those of must fermented without peels. However, the wines made using peeled mangoes were far more preferred by consumers than wine made using mangoes with peels. Five (5) major classes of aromatic volatiles were identified in all must and wine samples. Acetaldehyde and ethyl caprylate were present in all treatments, followed by isobutyraldehyde and 2, 3 Butanedione. Some volatiles identified appeared to be mango cultivar specific (Benzaldehyde and 1-methyl-2-pyrrolidone) while other volatiles appeared to be unique to the yeast strain employed (Ethyl butyrate). Keywords: mango, peels, yeast, must, wine, volatiles, alcoho

Fermentation Capacity of Yeasts Using Mango (Mangifera indica Linn.) as Substrate

The goal of this study was to address the problem of large post harvest losses of mangoes by employing yeast fermentation technology to produce a more stable, value-added product in this case fruit wine. The design of the study involved determination of the fermentative capabilities of four commercial yeast types on musts obtained from an improved (Keitt) mango cultivar that is popularly cultivated in some parts of Ghana for export. The characteristics of the mango musts that were monitored included total soluble solids (TSS), pH and total acidity (TA), microbial populations (aerophilic mesophiles, yeasts and Acetic acid Bacteria), alcohol content and colour over the course of the fermentations. Descriptive and hedonic sensory evaluation was carried out on the ferments obtained from all treatments. Results showed that two of the yeast types namely; Red Star Pasteur and Red Star Montrachet displayed superior fermentation characteristics and produced mango wines that were acceptable by both descriptive and affective sensory panels. Keywords: mango, yeast, fermentation, alcohol, wine, must, soluble solids, acidity

Prevalence and genomic characterization of Salmonella isolates from commercial chicken eggs retailed in traditional markets in Ghana

Salmonella enterica are important foodborne bacterial pathogens globally associated with poultry. Exposure to Salmonella-contaminated eggs and egg-related products is a major risk for human salmonellosis. Presently, there is a huge data gap regarding the prevalence and circulating serovars of Salmonella in chicken eggs sold in Ghana. In this study, 2,304 eggs (pools of six per sample unit) collected from informal markets in Accra, Kumasi and Tamale, representing the three ecological belts across Ghana, were tested for Salmonella. Antimicrobial susceptibility testing and Whole Genome Sequencing (WGS) of the isolates were performed using standard microdilution protocols and the Illumina NextSeq platform, respectively. The total prevalence of Salmonella was 5.5% with a higher rate of contamination in eggshell (4.9%) over egg content (1.8%). The serovars identified were S. Ajiobo (n = 1), S. Chester (n = 6), S. Hader (n = 7), S. enteritidis (n = 2); and S. I 4:b:- (n = 8). WGS analysis revealed varied sequence types (STs) that were serovar specific. The S. I 4:b:- isolates had a novel ST (ST8938), suggesting a local origin. The two S. enteritidis isolates belonged to ST11 and were identified with an invasive lineage of a global epidemic clade. All isolates were susceptible to ampicillin, azithromycin, cefotaxime, ceftazidime, gentamicin, meropenem, and tigecycline. The phenotypic resistance profiles to seven antimicrobials: chloramphenicol (13%), ciprofloxacin (94%), and nalidixic acid (94%), colistin (13%), trimethoprim (50%) sulfamethoxazole (50%) and tetracycline (50%) corresponded with the presence of antimicrobial resistance (AMR) determinants including quinolones (gyrA (D87N), qnrB81), aminoglycosides (aadA1), (aph(3“)-Ib aph(6)-Id), tetracyclines (tet(A)), phenicols (catA1), trimethoprim (dfrA14 and dfrA1). The S. enteritidis and S. Chester isolates were multidrug resistant (MDR). Several virulence factors were identified, notably cytolethal distending toxin (cdtB gene), rck, pef and spv that may promote host invasion and disease progression in humans. The findings from this study indicate the presence of multidrug resistant and virulent strains of Salmonella serovars in Ghanaian chicken eggs, with the potential to cause human infections. This is a critical baseline information that could be used for Salmonella risk assessment in the egg food chain to mitigate potential future outbreaks

酵素のパーム核油の水抽出への応用

パーム核油の水抽出に酵素を応用した。パーム核を粉砕し、色々な酵素で、水浮遊法でパーム核油を抽出した。粗酵素のセルラーゼルとヘミルラーゼまたは、さらに、プロテアーゼとペクチナーゼを同時に作用させると油の回収率が高くなった。それぞれの酵素を1%ずつ用いた場合が最高の収率になった。また、収率はpH及び粉砕物と水との混合割合によって影響された。pHは回取された油中の遊離脂肪酸の値に影響した。この酵素法で伝統的なパーム油の製造法を改良出来ることが分かった。An enzyme-assisted fat extraction technique has been applied to the aqueous extraction of palm kernel oil. Palm kernel meal samples were prepared and treated with different enzymes prior to extraction. The oil was then extracted using a water floatation method. Treatments with a crude enzyme with both cellulase and a hemicellulase activities, only or in combination with a protease and a pectinase, all resulted in higher palm kernel oil yield than control treatments. Optimum yield occurred when a protease, a pectinase and the cellulase/hemicellulase enzymes were combined, each at 1% concentration. Yield was influenced by the pH of the meal suspension and the meal/water ratio during the enzyme treatment. The former seemed to affect the free fatty acid values of the enzyme-assisted extracted palm kernel oil. The observations suggested that the enzyme-assisted aqueous extraction method could be used to improve the viability of the traditional palm kernel oil process

SUITABILITY OF CARAMBOLA (AVERRHOA CARAMBOLA) FRUIT JUICE AS A SUBSTRATE FOR WINE FERMENTATION

The physico-chemical characteristics of carambola (Averrhoa carambola) fruit juice were determined to assess the suitability of the fruit as raw material for local wine production. Fresh ripe fruits of the carambola tree (Averrhoa carambola) were processed into a fruit juice. The juice was analysed to determine moisture, fat, total solids, soluble solids, total sugars, and vitamin C content, the types of sugars present, titratable acidity and pH. The fruit had a characteristic soft, fragile and thin skin, relatively few and tender seeds, and a high water content (94%) which made its processing into a fruit juice fairly simple and easy. A juice yield of about 76% was observed. The juice was yellowish in colour. Some physico-chemical characteristics of the fruit juice were: pH 2.2, total solids 5.9%, soluble solids 5.0%, titratable acidity 0.66, fat 0.25% and total sugars 2.55%. The analysis of the sugars showed glucose, fructose and sucrose as the predominant sugars present. Vitamin C content was substantially high (35 mg/100 g), but fat content was low (0.25%). The total sugars content and pH were very low. Most brewer\'s yeasts require a pH range of 4-6; and for adequate alcohol production to form a wine, the sugar content should be about 10%. The physico-chemical characteristics of the juice suggest the feasibility of modifying the juice into a suitable must that could yield adequate amount of alcohol to form a wine. The carambola fruit is, therefore, considered as a suitable raw material for wine production locally. Key Words: Carambola (Averrhoa carambola), carambola fruit juice, wine production UTILISATION DU JUS DE CARAMBOLA (AVERRHOA CARAMBOLA) COMME SUBSTRAT DE FERMENTATION DU VIN NOTE DE SYNTHESE Les caractéristiques physico-chimiques du jus de carambola (Averrhoa carambola) ont été déterminées afin d\'évaluer la convenance du fruit comme matière première dans la production locale de vin. Les fruits mûrs frais de l\'arbre de carambola (Averrhoa carambola) ont été transformés en un jus. Ce dernier a été analysé afin de déterminer la teneur en humidité, graisse, matières sèches, matières solides solubles, sucres et vitamine C. L\'analyse a également révélé les types de sucres que le jus contient, l\'indice d\'acide ainsi que le pH. Le fruit avait une peau caractéristique douce, fragile et mince, avec des graines tendres et relativement peu nombreuses. En outre, il contenait un niveau élevé d\'eau (94%) qui a permis une transformation très simple et facile du fruit en un jus. Son rendement en jus était d\'environ 76%. Le jus était de couleur jaune. Quelques caractéristiques physico-chimiques constatées dans ce jus étaient les suivantes: pH 2,2, total matières sèches 5,9%, matières solides solubles 5,0%, indice d\'acide 0,66, graisse 0,25% et teneur en sucres 2,55%. L\'analyse a montré la prédominance du glucose, du fructose et du saccharose. La teneur en vitamine C était considérablement élevée (35mg/100 g) alors que celle en matières grasses était faible (0,25%). La teneur en sucres et le pH étaient très faible bas. La plupart des levures de bière exigent un pH de l\'ordre de 4-6. En outre, pour qu\'une production adéquate d\'alcool puisse former un vin, la teneur en sucres devrait être d\'environ 10%. Les caractéristiques physico-chimiques du jus suggèrent la faisabilité de la modification du moût approprié qui pourrait rapporter une quantité adéquate d\'alcool pour former un vin. Par conséquent, le fruit du carambola est considéré comme une matière première appropriée dans la production locale de vin. Mots-clés: Carambola (Averrhoa carambola), jus du carambola, production du vin AJFAND Vol.4(2) 200