Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Smoked Sardinella sp. in Ghana: Impact of an Improved Oven on Public Health Protection.

An improved fish smoking oven called FAO-Thiaroye Technique (FTT) has been introduced in Ghana and other countries in the Global South as a technical intervention for the high levels of polycyclic aromatic hydrocarbons (PAHs) in traditionally smoked fish produced in those regions. This study evaluated the extent to which the intervention reduces consumer exposure to PAHs (considering benzo(a)pyrene [BaP] as a marker) in smoked fish, using Ghana as a case. Smoked Sardinella sp. were sampled from two traditional ovens (Chorkor smoker and metal drum oven) and the FTT and their PAH levels were determined by gas chromatography-mass spectrometry. Samples of the product were also purchased from informal markets in three selected regions of Ghana and analyzed for their PAH levels. Cross-sectional consumer surveys were conducted in the selected regions to determine intakes of the commodity. A probabilistic risk assessment of PAH was then done by the margin of exposure (MoE) approach. BaP MoE as low as 1,060 and 752 were obtained for products from the traditional ovens and the informal markets, respectively, whereas the lowest value for FTT products was approximately 161,000. MoE values less than 10,000 were considered to denote a serious public health concern requiring risk management action. Therefore, the findings suggest that there is a potential health concern of high consumer exposure to PAHs in traditionally smoked fish in Ghana, and that the FTT is a technically viable intervention for the problem.

Reducing polycyclic aromatic hydrocarbon contamination in smoked fish in the Global South: a case study of an improved kiln in Ghana.

BACKGROUND: Smoked fish is a major source of animal protein in developing countries. It is largely produced by hot-smoking on traditional kilns using fuelwood. This practice is associated with high polycyclic aromatic hydrocarbon (PAH) contamination in products, with consequences for public health. An improved kiln, comprising the FAO-Thiaroye Technique (FTT), has been introduced by the Food and Agriculture Organization of the United Nations to address such a concern. The present study investigated the efficacy of the FTT in Ghana through comparative fish smoking experiments with traditional kilns followed by determination of PAH levels [benzo(a)pyrene (BaP) and PAH4] in the products by gas chromatography-mass spectrometry. For each kiln, the effect of smoking fuel type on PAH contamination was determined. The impact of the design characteristics of the FTT on the levels of the compounds was also determined. RESULTS: Mean BaP and PAH4 levels in the FTT products were up to 1.8 and 7.6 µg kg-1 , respectively, whereas the corresponding levels in traditional kiln products were up to 70 and 395 µg kg-1 . PAH levels in FTT products were below European Union regulatory limits, whereas levels in traditional kiln products exceed such limits by up to 33-fold. Across kiln types, the use of wood fuels caused higher PAH contamination compared to the use of fully-lit charcoal as an alternative fuel. CONCLUSION: The improved kiln (FTT) is efficacious in yielding smoked fish with a PAH content lower than the levels in traditional kiln products and also below current regulatory limits. Kiln design and type of processing fuel have significant impacts on PAH contamination during fish smoking. © 2019 Society of Chemical Industry.

Tilapia consumption patterns and consumer preferences: Predictors and perspectives of consumers in Ghana.

The objective of this study was to assess consumer behaviour towards tilapia and tilapia products and provide information linking production with consumption patterns and preferences as well as to predict factors that influence consumer preference, purchase behaviour, and willingness to patronize tilapia fillets using classification and regression trees. A total of 960 responses were obtained using convenient sampling. The findings of this survey indicate that tilapia is eaten mainly because of its taste. Regarding the various cooked tilapia options available in Ghana, 58.5 % preferred charcoal-grilled tilapia while sixty-six per cent (66 %) preferred to purchase their tilapia in the fresh state. Furthermore, sixty-five per cent (65 %) of the participants revealed that they consume tilapia at least once a month, indicating a link between production and consumption, as well as a continuous market for tilapia fish farmers. Most respondents (85 %) would prefer an easier way to prepare tilapia. The availability of tilapia in a fillet form appealed to about 50.8 % of respondents with 78 % indicating that they would purchase tilapia fillets if they were available on the market. For the parts of tilapia consumed, 70 % indicated that the head of tilapia was important to them and only 49 % of respondents indicated they would buy fillets without the head. The top three preferred fillet options in increasing order were chilled, frozen, and spiced. From the study of associations, income was the most important factor determining whether a consumer would purchase tilapia fillets or not. However, with regards to preference of head or tail region, age was the most important determining factor. Thus, consideration of all these factors would serve as a guide to businesspeople and actors within the tilapia value chain in Ghana and beyond.

Assessing aflatoxin safety awareness among grain and cereal sellers in greater Accra region of Ghana: A machine learning approach.

Studies have established high prevalence of aflatoxin contamination in grains and cereals produced in Ghana. Mitigation strategies have focused mainly on capacity building for farmers, agricultural extension officers, bulk distributors and processors to the detriment of the market women who act as the final link between consumers and producers. This study used supervised machine learning algorithms by means of Classification and Regression Trees (CART) to investigate aflatoxin knowledge and awareness of market women in Greater Accra Region of Ghana. A cross-sectional survey and probability sampling methods were employed for data collection. Ninety-two (92%) of participants had never heard about aflatoxins and yet, 62% reported that they usually observe mould growth in their cereals/grains. Unsurprisingly, 97% of participants indicated that they had no knowledge of the aflatoxin bill passed by the government of Ghana parliament. Despite participants not being aware of aflatoxin menace, the percent correctness of their aflatoxin safety measure score was 40%. A regression tree algorithm showed that, participant's ethnic group was the most significant parameter to consider regarding their aflatoxin safety knowledge. Their educational background and age were 95.5% and 72.5% as significant as their ethnic group. A classification tree algorithm showed that, educational level was the most significant parameter to consider when it comes to sorting of grains/cereals. Their ethnic group and marital status were 92.4% and 89.3% as important as educational level. It is therefore imperative for the Ghana government to extend sensitization and awareness programs to these market women, targeting the uneducated and specific age and ethnic groups.

The microbiology of alkaline-fermentation of indigenous seeds used as food condiments in Africa and Asia.

Alkaline-fermented food condiments play an important role in the diets of many people in developing and a few developed countries. The rise in pH during production of these foods is due to the ability of the dominant microorganisms, Bacillus spp., to hydrolyze proteins into amino acids and ammonia. Studies have been undertaken which have investigated a number of these products like dawadawa, ugba, bikalga, kinema, natto, and thua-nao. In this review, current knowledge about the principal microbiological activities and biochemical modifications which occur during the processing of the alkaline condiments including nutritional, antimicrobial, and probiotic aspects are discussed. The current use of molecular biology methods in microbiological research has allowed unambiguous and more reliable identification of microorganisms involved in these fermentations generating sufficient knowledge for the selection of potential starter cultures for controlled and better production procedures for alkaline-fermented seeds condiments.

The comparative ability of four isolates of Bacillus subtilis to ferment soybeans into dawadawa.

In an attempt to develop starter cultures for fermenting soybeans into the traditional West African condiment dawadawa, four isolates of Bacillus subtilis: 24BP(2), 72RP(17), 72BP(30), and FpdBP(2), which had been selected from 42 Bacillus cultures in a previous study by the current authors, were used separately to produce soy-dawadawa. The accompanying microbiological and biochemical changes, including enzymatic activities, as well as the organoleptic quality of the products were evaluated including that of a control sample which was fermented spontaneously. Significant differences existed in the ability of the four isolates to hydrolyse the soybean proteins, starch, and fat to produce dawadawa. Bacillus subtilis 24BP(2) recorded the highest protease and amylolytic activities, 101 U/ml and 26.68 mg/ml, respectively, and liberated the most amino acids, 117.64 mg/g dry wt., during fermentation. Bacillus subtilis 24BP(2) also grew to the highest population of cells in the final product. Taste panelists found soybean dawadawa produced by each of the four isolates acceptable and rated soup flavoured with soy-dawadawa produced by Bacillus subtilis FpdBP(2) as the best sample. Panelists scored it higher than the control sample and soy-dawadawa produced by Bacillus subtilis 24BP(2) in that order.

Screening of 42 Bacillus isolates for ability to ferment soybeans into dawadawa.

Forty-two cultures of Bacillus species isolated from soybean dawadawa were screened for their proteolytic activity on Skim Milk Agar, amylolytic activity on Starch Agar, and ability to grow on Soybean Agar. Distinct differences were observed between the cultures for all the criteria. Eleven isolates were selected for laboratory fermentation trials and each produced soybean dawadawa which was found acceptable by a taste panel. The pH of the samples, which increased from 6.37-6.58 to 8.22-8.85 during fermentation, were significantly different at P< or =0.05 for the different cultures. In the fermented samples, Bacillus counts exceeded 10(9) cfu/g, with the population of only one sample being significantly different at P< or =0.05. A market focus group familiar with soybean dawadawa selected Bacillus subtilis 24BP(2) and B. subtilis FpdP(2) as the best potential starter cultures. A taste panel found no significant differences in overall acceptance between soybean dawadawa either fermented spontaneously or with B. subtilis 24BP(2) and also between soybean dawadawa fermented with either B. subtilis 24BP(2) or B. subtilis FpdP(2).

Effect of boiling and roasting on the fermentation of soybeans into dawadawa (soy-dawadawa).

Soybeans which had initially been dehulled by either boiling (boiled/dehulled) or roasting (roasted/dehulled) before peeling, were cooked and fermented into dawadawa, a traditional food condiment. The micropopulation, enzymatic activities, proximate composition, amino acid, and aroma profiles of the two types of soybean dawadawa were evaluated during fermentation. Only minor differences were found in the microbial profiles of the two types of soy-dawadawa. Although boiled/dehulled soy-dawadawa initially had lower microbial counts, it recorded higher counts at the advanced stages of fermentation. Proteolytic and amylolytic Bacillus species including Bacillus subtilis, Bacillus pumilus, Bacillus licheniformis, Bacillus cereus, and Bacillus firmus dominated the micropopulation of the two types of soy-dawadawa with Bacillus subtilis accounting for about 50% of the Bacillus species in all samples. Lactic acid bacteria and yeasts occurred in low numbers in the two types of soy-dawadawa. The proximate composition of the two types of soy-dawadawa were similar, and their contents of moisture and protein increased whilst fat and ash decreased during fermentation. Both types of fermenting soy-dawadawa recorded similar levels of alpha-amylase activity, but boiled/dehulled soy-dawadawa showed slightly higher protease activity. The levels of isoleucine, leucine, lysine, phenylalanine, arginine and proline increased significantly with fermentation time in both types of soy-dawadawa. With respect to differences in their aroma profiles, hexanodecanol, octadecyl acetate, 1,2-dimethyl benzene, tetradecene, (E)-5-eicosene, cyclohexadecane, and hexacosane were found only in the roasted/dehulled samples, whilst 1,2-ethanediol, ethyl acetate, dimethyl disulfide, cyclotetradecane, decene, indole , 2 butyl-octenal, acetophenone, and toluene were found only in the boiled/dehulled samples. A market focus group showed preference for roasted/dehulled soy-dawadawa over boiled/dehulled soy-dawadawa. Apart from the volatile aroma compounds, the biochemical and microbiological profiles of the two types of soy-dawadawa showed only minor differences and were also similar to the profiles reported for African locust bean dawadawa.

Souring and breakdown of cyanogenic glucosides during the processing of cassava into akyeke.

The population and composition of the lactic acid bacteria microbiota as well as the content of cyanogenic glucosides occurring at various stages of fermentation and subsequent processing of cassava roots into akyeke, a steamed sour cassava meal, were investigated. The number of lactic acid bacteria and percentage titratable acidity increased during 5 days of fermentation, but decreases were observed in the subsequent operations of 'washing' the dough with water followed by partial drying and steaming. In field and laboratory samples, Lactobacillus plantarum accounted for 59.3% and 52.3%, Lactobacillus brevis 23.3% and 22.8% and Leuconostoc mesenteroides subsp. cremoris 14.5% and 15.8%, respectively, of all lactic acid bacteria isolated at various stages of fermentation and processing. A reduction of about 98% occurred in the total cyanogens (CN) content of cassava roots during processing, from 69.3 to 1.4 and 110.3 to 2.8 mg CN equivalent/kg dry weight for laboratory and field samples of akyeke, respectively.

Antimicrobial interactions of microbial species involved in the fermentation of cassava dough into agbelima with particular reference to the inhibitory effect of lactic acid bacteria on enteric pathogens.

Lactic acid bacteria, Bacillus species and yeasts are involved in the fermentation of cassava dough into agbelima. Microbial interactions within and between these groups of microorganisms were investigated in addition to the survival of five enteric pathogens inoculated into agbelima under various conditions. Nine out of 10 cultures of lactic acid bacteria isolated at the end of agbelima fermentation showed inhibitory effect against 10 cultures of lactic acid bacteria isolated at the start of fermentation. Only 3 out of 10 isolates of Bacillus subtilis were inhibited by 10 isolates of lactic acid bacteria tested. No interactions were observed between yeasts and the lactic acid bacteria, whereas three of the Bacillus isolates showed inhibitory effects against the yeasts. Twelve isolates of Lactobacillus plantarum tested inhibited the growth of an isolate each of Lactobacillus fermentum and Lactobacillus brevis but none tested positive for bacteriocin production. The antimicrobial effect of the lactic acid bacteria was attributed to acid production. In fermenting cassava dough, enteric pathogens survived to different extents depending on pH and their sensitivity to acids. Vibrio cholerae C-230, Salmonella typhimurium 9 and Salmonella enteritidis 226 were not detectable in 10 g of sample after 4 h when inoculated into the 48-h fermented product, agbelima, whereas Shigella dysenteriae 2357T and Escherichia coli D2188 were detectable up to 8 h in the product.

Microbial modification of the texture of grated cassava during fermentation into akyeke.

The traditional akyeke inoculum and fermenting akyeke, an indigenous cassava product, were investigated to identify microbial species responsible for the modification of cassava texture during fermentation. Both field and laboratory samples were examined and only some cultures isolated on Plate Count Agar and Malt Extract Agar were found to be capable of causing a softening of cassava tissue when plated directly on sterile cassava slices. The cassava tissue softening isolates on PCA were tentatively identified as Bacillus subtilis and isolates on MEA as Candida tropicalis and Zygosacchromyces florentinus. The population of B. subtilis in the laboratory sample of inoculum was found to be 2.4 x 10(9) cfu g(-1) and increased during dough fermentation from 1.1 x 10(7) to 3.5 x 10(9) cfu g(-1) after 96 h. C. tropicalis was present in the inoclum at 3.0 x 10(9) cfu g(-1) and increased during dough fermentation from 3.2 x 10(6) to 6.9 x 10(7) cfu g(-1) whilst Z. florentinus was present in the inoclum at 9.1 x 10(8) cfu g(-1) and increased from 8.1 x 10(5) to 7.5 x 10(6) cfu g(-1) during dough fermentation.

Genotyping of starter cultures of Bacillus subtilis and Bacillus pumilus for fermentation of African locust bean (Parkia biglobosa) to produce Soumbala.

Bacillus spp. are the predominant microorganisms in fermented African locust bean called Soumbala in Burkina Faso. Ten strains selected as potential starter cultures were characterised by PCR amplification of the16S-23S rDNA intergenic transcribed spacer (ITS-PCR), restriction fragment length polymorphism of the ITS-PCR (ITS-PCR RFLP), pulsed field gel electrophoresis (PFGE) and sequencing of the 968-1401 region of the 16S rDNA. In previous studies, the isolates were identified by phenotyping as Bacillus subtilis and Bacillus pumilus. The phenotyping was repeated as a reference in the present study. The ITS-PCR and ITS-PCR RLFP allowed a typing at species level. The PFGE was more discriminative and allowed a typing at strain level. Full agreement with the phenotyping was observed in all cases. The sequencing of the 16S rDNA allowed the identification at species level with an identity from 97% to 100% comparing the sequences to those from the GenBank databases. The desired cultures of B. subtilis and B. pumilus from African locust bean fermentation were distinguished by ITS-PCR and ITS-PCR RLFP from Bacillus cereus and Bacillus sphaericus which sometimes occur in the beginning of the fermentation.