Browsing by Author "Ayernor, G.S."
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Item Aerobic spore-forming bacteria and chemical composition of some Nigerian fermented soup condiments(Plant Foods for Human Nutrition, 2000-02) Sanni, A.I.; Ayernor, G.S.; Sakyi-Dawson, E.; Sefa-Dedeh, S.A total of 97 strains of spore-forming Bacillus were isolated from 45 samples of three Nigerian fermented condiments, obtained from retail markets located in Southwestern Nigeria. The isolates were identified as B. subtilis (33%), B. pumilus (19%), B. licheniformis (22%), B. brevis (9%), B. megaterium (12%) and B. polymyxa (5%). The microbial load of the condiments showed that the average count of spore-formers was between 107 to 109 cfu/g. The moisture contents of iru, ugba and ogiri were 57.18%, 46.32% and 42.34%, respectively, while the protein contents were 18.26%, 17.17% and 17.96%. The percentage fat was 29.88%, 40.25% and 44.14% for iru, ugba and ogiri. The ash content ranged from 5.8 to 6.1%; a 0.1% titratable acidity and pH values above 7.0 were obtained for the three condiments.Item Biochemical Changes and Aroma Development during the Spontaneous Fermentation of Cassava Fish into Lanhouin and Their Influence on Product Acceptability(Journal of Aquatic Food Product Technology (18): 370-384, 2009) Anihouvi, V.B.; Sakyi-Dawson, E.; Ayernor, G.S.; Hounhouigan, J.D.Lanhouin, a fermented product from cassava fish (Pseudotolithus sp.), was produced by spontaneous fermentation with inherent risks of quality defects. In this respect, changes in moisture, protein, free fatty acids, total volatile nitrogen, and histamine were monitored during the fermentation period using Pearson’s and AOAC methods. The aroma compounds were detected using the Likens-Nickerson extraction method and gas chromatography/mass spectrometry (GC-MS) analysis. The results showed that the moisture and protein contents decreased while free fatty acid (FFA) and total volatile nitrogen (TVN) increased during fermentation. In contrast, there was no linear relationship between the histamine content and fermentation time since the histamine values didn’t increase continuously as fermentation progressed. A total of 94 compounds were detected in the fermenting fish over a period of 8 days, and 82 compounds were positively identified with a quality index higher than 70%. The compounds included 15 aliphatic hydrocarbons, 9 esters, 9 ketones, 9 amines, 7 aldehydes, 6 aromatic hydrocarbons, 7 acids, 6 thiazoles, 5 alcohols, 3 phenols, 2 amides, 2 furans, and 2 pyrroles.Item Effect of blanching and frying on textural profile and appearance of yam (Dioscorea rotundata) French fries(Journal of Food Processing and Preservation, 2015-06) Graham-Acquaah, S.; Ayernor, G.S.; Bediako-Amoa, B.; Saalia, F.S.; Afoakwa, E.O.; Abbey, L.Response surface methodology was employed to characterize the effects of blanching temperature, blanching time and final frying time on texture and appearance of fried yam chips produced from two cultivars of white yam (Dioscorea rotundata). Fifteen treatment combinations were derived from Box-Behnken design (k=3) and run. Analysis of variance and multiple linear regression analyses were conducted to determine the effects of factors on the texture and color indices and to fit models for predicting the response variables. There were differences in the effects of the same set of factor combinations on textural attributes (hardness, fracturability, cohesiveness, gumminess and chewiness) and color (L, a, b) indices of the two cultivars used. Blanching temperature and frying time had a greater impact on texture and appearance of fried chips than blanching time. Adequately fitted models were derived for predicting the effects of blanching and frying on the textural profile and color of yam chips. © 2013 Wiley Periodicals, Inc.Item Effects of Processing Methods on the Quality of Palm Oil in Ghana(University of Ghana, 1999-12) Mensah, N.K.; Ayernor, G.S.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Nutrition and Food SciencePalm oil samples from GOPDC, TOPP and two traditional methods (Kyembe and Bedo) were analysed using the following quality indices: moisture content, refractive index, percentage FFA, peroxide value and TBA value. They were examined with regards to the determination of the effect of industrial processing methods on the quality of palm oil; the effect of traditional processing methods on the quality of palm oil; the relative efficacy of the processes in the production of good quality crude palm oil. Processing altered significantly better the physical indices o f quality (moisture content, refractive index) in all the processes (GOPDC, TOPP, Kyembe and Bedo). There was no significant alterations in the chemical indices o f quality in all the processes except in FFA for TOPP, which produced significant differences in the percent FFA which ranged from 2.34 percent to 2.66 percent. Using their final stages of processing (storage tank stage for industrial processes; and "frying" stage for Kyembe and boiling stage for Bedo) the industrial methods produced significantly better quality palm oil than the traditional methods with regards to moisture content (industrial processes 2.40 percent; traditional processes, 5.32 percent PO.V. (industrial processes 2.94m Eq/Kg, traditional processes, 3.05m Eq/Kg) TBA values (industrial processes, 0.14; traditional processes 0.16). It was recommended that traditional processors be informed as to the effect of certain practices they engage in on the quality of their oil; traditional methods of processing palm oil in the palm oil producing zones be researched into; and the refined, bleached and deodorised method be included in a future study to bring the whole study to its logical conclusion.Item Effects of two pre-treatments, blanching and soaking, as processing modulation on non-enzymatic browning developments in three yam cultivars from Ghana(Heliyon, 2021) Quayson, E.T.; Ayernor, G.S.; Johnson, P.T.; .Ocloo, F.C.K.Non-enzymatic browning develops in dry-cooked foods and those with high carbohydrate develop acrylamide, a neurotoxin and potential carcinogen. However, some non-enzymatic browning products have reducing properties. We hypothesized that non-enzymatic browning and reducing power, a measure of antioxidant activity, of processed yam are affected by pre-treatment. Peeled yam cultivars (KM, RKD and SO89) in chunks were pre-soaked (0, 3, 6, 12, 18, and 24 h) in distilled water or pre-blanched (0, 1, 2, 3, 4, and 5 min) in steam. Pre-treated samples were deep-fried at 180 °C for 15 min or roasted at 220 °C for 30 min. Soluble solids, titratable acidity and pH of yam tissues and soaking water were determined. pH of the soaked yam tissues showed a positive relation with non-enzymatic browning. Pre-soaked fried KM and roasted RKD showed a significant decrease in non-enzymatic browning intensities. The reducing power of the cooked yams ranged between 78.94 and 185.92 % of ascorbic acid, and was affected by the different pre-treatment and dry-cooking methods.Item Influence of processing conditions on the nutritive value of Ogi-Baba, a Nigerian fermented sorghum gruel(Plant Foods for Human Nutrition, 2001-02) Sanni, A.I.; Steiner-Asiedu, M.; Ayernor, G.S.The effect of germination, cowpea fortification and fermentation on the chemical and amino acid composition of ogi-baba, a Nigerian fermented sorghum gruel was investigated. The lowest protein value of 1.4% was obtained in the traditionally prepared sample, while samples prepared from germinated, fortified sorghum had 13%. The ash ranged from 0.9% to above 2%, while the fat was in the range of 1.2% to 2.8%. Generally, fortification, in addition to germination, improved the chemical composition of ogi-baba relative to the control sample. There was improvement in the amino acid profile of all the ogi-baba samples compared to the unprocessed sorghum grains. Lysine, a limiting amino acid in sorghum, increased more than 50% in ogi-baba. However, samples prepared using germinated sorghum without the addition of cowpeas had a lower lysine content.Item Microbiological changes in naturally fermented cassava fish (Pseudotolithus sp.) for lanhouin production(International Journal of Food Microbiology (116): 287-291, 2007) Anihouvi, V.B.; Sakyi-Dawson, E.; Ayernor, G.S.; Hounhouigan, J.D.Cassava fish (Pseudotolithus sp.) was naturally fermented on three different occasions at room temperature (28–30 °C) for 3 to 8 days and the microbial population and the occurrence of various bacterial species were monitored. In general, after a slight increase during the early stages of fermentation, the microbial population decreased as the fermentation progressed. A total of 224 isolates belonging to the genera Bacillus, Staphylococcus, Micrococcus, Streptococcus, Corynebacterim, Pseudomonas, Achromobacter and Alcaligenes were isolated from the fermenting fish samples and the predominant ones were identified at the species level. Bacillus spp. and Staphylococcus spp. were the predominant genera and accounted for 48.7% and 27.3% of the total number of isolates respectively. Bacillus subtilis and Bacillus licheniformis, Staphylococcus lentus and Staphylococcus xylosus and Micrococcus luteus were the representative strains isolated during the fermentation. Bacillus spp., Staphylococcus spp. and Micrococcus spp. initiated the fermentation but Micrococcus spp. were few in numbers and died off after four (4) days of fermentation while Bacillus spp. and Staphylococcus spp. persisted up to the end of fermentation. Enterobacteriaceae were fewer in numbers at the start of fermentation (102 cfu/g) and their numbers decreased to less than 10 cfu/g after two days of fermentation. Bacillus spp. as well as Staphylococcus spp. isolated possessed moderate proteolytic and lipolytic activities. Micrococcus spp. showed weak proteolytic activity and no lipolytic activity.Item Microflora and chemical composition of Momoni, a Ghanaian fermented fish condiment(Journal of Food Composition and Analysis, 2002-10) Sanni, A.I.; Asiedu, M.; Ayernor, G.S.A total of 67 microbial strains were isolated from momoni, a Ghanaian fermented fish condiment obtained from retail outlets. The strains belonged to nine genera of micro-organisms namely Bacillus, Lactobacillus, Pseudomonas, Pediococcus, Staphylococcus, Klebsiella, Debaryomyces, Hansenula and Aspergillus with Bacillus having a predominant occurrence of 37.7%. Average values of 5.8 × 107 - 4.1 × 108 cfu/g were obtained for the microbial count. The chemical constituents of fermented fish condiment were a moisture content of 50%, protein values of 16.8-21.9%, a titratable acidity of 2%, and a pH of above 6.0. The predominant amino acid of the momoni samples was glutamic acid (12.4-14.5%). The high pH and the low level of lactic acid bacteria (103 cfu/g) and the high salt content of momoni (294-310/kg) suggest that the fermentation process of the fish condiment is mediated by the endogenous enzymes of the fish rather than the associated micro-organisms. © 2002 Elsevier Science Ltd. All rights reserved.Item Non-enzymatic browning and estimated acrylamide in roots, tubers and plantain products(Food Chemistry, 2007-12) Quayson, E.T.; Ayernor, G.S.Acrylamide has been discovered in foods, especially high carbohydrate foods that are dry-cooked (baked, fried or roasted) at high temperatures which also create the conditions for non-enzymatic browning. Baking, frying and roasting are common food preparation methods in Ghana. Fifteen different high carbohydrate foods in Ghana, that undergo dry-cooking, have been investigated for non-enzymatic browning and acrylamide production. The products that showed notable non-enzymatic browning and acrylamide levels include fried sweet potato, plantain chips from the fresh produce, with their respective non-enzymatic browning and acrylamide values as 0.095 ± 0.006 optical density (OD), 1043 ± 47.6 parts per billion (ppb); 0.034 ± 0.03 OD, 568 ± 22.9 ppb. Roots and tuber products had relatively high non-enzymatic browning and acrylamide levels while plantain products showed low levels of non-enzymatic browning and acrylamide. © 2007 Elsevier Ltd. All rights reserved.Item Physical, chemical and microbiological changes in alcoholic fermentation of sugar syrup from cassava flour(African Journal of Biotechnology, 2008-07) Ocloo, F.C.K.; Ayernor, G.S.Changes in alcoholic fermentation of sugar syrup produced from cassava flour with Saccharomyces cereviseae (baker's yeast) were investigated. Cassava flour paste was hydrolysed using rice malt to produce hydrolysate (sugar syrup), which was fermented at 28 - 30 °C for 1, 2, 3, 4 and 5 days. The fermented sugar syrup was analysed for alcohol content, reducing sugars, specific gravity, soluble solids, pH, volatile acids and total acidity using standard analytical methods. Yeast growth was also monitored. Results showed that pH values decreased with increased total acidity with concomitant increase in yeast growth (biomass) and alcohol contents of the fermenting sugar syrup. There were decreases in soluble solid contents, refractive indices of the fermenting medium. Volatile acids (as acetic acids), increased with alcoholic fermentation. Fermentation of sugar syrup from cassava flour is associated with physical and chemical changes that occur in other form of fermentation alongside increased in biomass. © 2008 Academic Journals.Item Physical, Chemical and Physiological Responses of Pineapple to Glazing after Harvest.(University of Ghana, 1997-08) Bartels, P.K.; Ayernor, G.S.; University of Ghana, College of Basic and Applied Sciences , School of Biological Sciences, Department of Nutrition and Food ScienceThe post-harvest management of pineapple quality is a problem that many Ghanaian pineapple exporters are grappling with. Importers pay premium only on top quality fruits that satisfy market and consumer expectation. An effective Quality Management Approach (QMA) which takes into consideration market demands and consumer expectation would be the key to making Ghanaian exports competitive on the world pineapple trade. In this study, glazing or surface coating of pineapple was employed as a QMA tool, and the physical, chemical and physiological responses of the fruit were monitored under ambient and refrigerated storage. The results of a comparative study of four levels of coating viz: 0, 5, 7.5 and 10% concentration showed that the physical and chemical quality attributes of pineapple could be enhanced by surface coating with the wettable emulsion "stay fresh 7055" and refrigerated storage at 8°C. 7.5% polymeric coated fruit gave the overall best quality attributes evaluated. However, 5% coating was preferred for further study because of economy and also because it was frequently observed that there was no significant difference in the treatment means of the 5% and 7.5% coated fruit. Refrigeration (8°C) minimised physical and chemical quality deterioration. However, fruit quality deteriorated when redrawn into physiological temperature (18°C and above). Physical and chemical quality deteriorated with increasing storage interval. Incorporating fungicide (thiobendazole) in the polymeric coating mixture had no significant effect on the quality indices studied. Mass Shrinkage Characteristics (SHC), Shell Colour Break (SCB) and Crown Withering Index (CWI) could be predicted using mathematical models. Mean SHC, SCB and CWI were significantly higher for fruits harvested at 160 days after floral induction (FI) than fruits harvested at 140 days FI. SHC and SCB were significantly higher for fruits evaluated at night (6pm - 6am) than for fruits evaluated during the day (6am - 6pm). 5% polymeric coating significantly arrested SHC, SCB and CWI under both low temperature (8°C) and ambient (28°) storage. Application of fungicide at 0.01% was significant in reducing shrinkage under ambient storage. Shrinkage Characteristic, Shell Colour Break and Crown Withering Index increased with increasing storage interval, but the effect was twice as much for ambient than for low temperature storage. The pineapple fruit exhibited a non-climacteric respiration. CO2 production and O2 utilisation increased with increasing holding time. The effect was more pronounced in non-coated than for coated fruit. Respiration Quotient (RQ) was 1.25 for coated and 1.92 for non-coated fruits. Nitrogen content in the storage atmosphere decreased with increasing holding time. Post Low Temperature Storage (LTS) behaviour of pineapple significantly affected the vitamin C content of whole fruit. 5% coating was effective in enhancing mean vitamin C retention by 27% over non-coated fruit 5 days after LTS. Sugar content, pH and pulp temperature increased while firmness retention deteriorated from the apical to the basal section of the fruit. Coated fruits were firmer, had higher pulp temperature and lower pH value. Internal browning was over 150% times more intense for non-coated fruits than for coated fruits. Internal browning and firmness retention could be predicted by linear mathematical models. Peroxidase activity determination in pineapple was optimised using the Central Composite Rotatable Design. Activity was highest at the basal section and showed a decreasing effect through the mid to the apical section. Maximum response to peroxidase activity was observed at pH range 5.5 - 6.0, using 0.5% 3.3’-dimethoxybenzidine and 0.15- 0.25% hydrogen peroxide. 5% polymeric coating was effective in delaying the onset of internal browning 5 days after LTS (8°C) and showed low peroxidase activity at 23°C. Non-coated fruit showed severe internal browning two days post LTS at 23°C ambient and had a higher peroxidase activity. Elevating conditioning temperature from 23°C to 30°C and 45°C respectively resulted in isozyme formation, an increase in peroxidase activity of polymeric coated fruit and a decreased activity in non-coated fruit. Finally, it can be concluded from the results of this study that glazing or surface coating holds great promise for the Ghanaian pineapple exporter in minimising the many physical, chemical and physiological disorders associated with the export trade.Item Storage and Packaging Studies on Degermed Maize Flour(University of Ghana, 2000-06) Houssou, P.A.F.; Ayernor, G.S.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Nutrition and Food Sciencedegermed maize flour (control). The percentage fat, ash, and fiber content were 1.42 } 0.34, 0.2 } 0.03, and 0.51 } 0.01 respectively for degenned maize flour and 6.02 } 0.63, 1.51 } 0.16, and 1.84 } 0.05 for non-degenned flour. Carbohydrate content was relatively higher (79.96%) in degenned maize flour than in the non-degermed maize flour which was 74.14% as a result of germ and hull. The moisture sorption isotherm of degermed maize flour (DF) and nondegermed maize flour (nDF) followed a type (II) isotherm pattern (Labuza,1984). The water absorption pattern of DF and nDF in relation to the various Water Activities (Aw) was higher for DF as compared to nDF at Aw between 0.11 to 0.71 indicating that the DF is more hygroscopic. DF showed a higher monolayer value of 3 .9g/l 00 solid matter as compared to nDF which was 2.98 g/100 solid matter. The heat of sorption of DF and nDF decreased with increasing moisture concentration. But at low Aw ranging from 0.11 to 0.44 the total heat of sorption of nDF is higher than that o f DF. Water vapor permeability test conducted on packaging materials used, showed that low Density Polyethylene has a higher water vapor transmission rate than Polypropylene (PP) and High Density (HD) which had s imilar rates. The initial moisture content of the flour samples ranged between 10.39 } 0.49% (solar dried sample) and 10.74 } 0.87% (Oven dried sample) for nDF, and 11.0 } 0.6 % (solar dried sample) and 10.57 } 0.78 % (Oven dried sample) for DF when packaged in HD and PP packaging materials and stored at 29 } 1°C. After.six months storage period, the final moisture content attained by both flour samples were between 10.63 } 0.63 % (Solar dried sample) and 12.61 } 0.77% (Oven dried sample) for nDF and 12.37 } 0.31% (Oven dried sample) and 11.27 } 0.48% (solar dried sample) for DF. These values are less than 13% moisture standard set for the storage of cereal flour (Kent, et al., 1970). After 6 months storage the non-degermed maize flour samples showed high percentage free fatty acid content (0.54 } 00 %) as compared to degermed maize flour samples (0.44 } 00 %) owing to the initial differences of fat content of the flour samples. Based on the results obtained it can be concluded that degermed maize flour can be stored for at least 6 months or longer with minimal changes in quality; and that the degermed maize flour has a higher potential for storage than the non-degermed maize flour.Item A Study of Beta-Carotene Stability in Processed Vitamin A-Rich Foods(University of Ghana, 1995-12) Adjei, M.D.; Ayernor, G.S.; University of Ghana,College of Basic and Applied Sciences,School of Biological Sciences,Department of Nutrition and Food ScienceVitamin A deficiency (VAD) is a public health problem in Ghana, leading to blindness. Year-round access to Vitamin A rich foods will curb its incidence. This study sought to identify appropriate processing, preservation and fortification methods to enhance E-carotene retention in foods towards VA alleviation. Carrots were steamed, blanched in water, NaHS03, NaCl or alkali rock salt (Kanwa) solutions. Amaranthus and Xanthosoma leaves were blanched in a range of kanwa solutions (0-0.1%) at varied temperatures (85-100°C) and time (4-10 min). The effect of the treatment and storage time (0-90 days) of the samples was studied by determining the S-carotene using HPLC. Ecarotene degradation in palm oil was evaluated at 100-200°C for0-240 min. Carrots and palm oil were incorporated into gari at0-20% by co-fermenting or fermenting before addition. Ecarotene stability was predicted with mathematical models during processing and storage. Highest E-carotene retention occurred in oven-dried NaCl, NaHS03 and kanwa treated carrots (22.9-65.6%) after storage. Kanwa blanching improved carotene retention during dehydration and storage of Amaranthus and Xanthosoma. Solar dried products had longer E-carotene half-lives (T1/2) than oven dried. High heating temperatures caused complete loss of E-carotene and color. Thermal degradation rates of 3.9-99.7 x 10"3 min'1 and an activation energy (EJ of 4.8 Kcal/mole in palm oil were calculated. Gari products fortified with carrots and palm oil had 13-28 and 11-20 mg/lOOg E-carotene respectively. Ecarotene losses occurred during fermentation (5-57%) and roasting (30-60%).The rate of E-carotene loss was slower in co-fermented products during storage. NaCl and kanwa could be used in the preservation of carotene in carrots. Carrot and palm oil fortification of gari improved its vitamin A and organoleptic properties. The use of palm oil in deep-fat frying is not recommended. Degradation kinetics and response surface plots generated from predictive models could establish the relationships between processing factors and E-carotene retention.Item Translocation of pesticide residues in cabbage(Elixir Food Science, 2012-04-24) Agyekum, A.A.; Ayernor, G.S.; Saalia, F.K.; Bediako-Amoa, B.The occurrence of pesticide residues in food matrices has become a necessity due to the toxicity and permanence of these xenobiotics. Translocation of pesticides in local and imported cabbage samples was investigated using Gas Chromatography/Mass Spectrophotometer (GC/MS) procedures. Cabbage samples were fractionated with respect to distance from the skin to the core and prepared for analysis. Results showed that organochlorine, organophosphate and synthetic pyrethroid residues were translocated in cabbage samples analysed. With respect to cabbage fractions, the outer pulp retained more of the residues than the pulp and the central core. On chemicals species, organochlorines were retained more in the outer pulp than the other fractions of the vegetables. Synthetic pyrethoid residues were restricted to the outer and inner pulp samples. All the chemical species identified were tanslocatable across the fractional parts of the vegetable with the exception of synthetic pyrethroid residues. There were significant differences in translocation and residue accumulation of pesticide among the fractional parts of the vegetable.Item Variability of sugars in staple-type sweet potato (Ipomoea batatas) cultivars: The effects of harvest time and storage(International Journal of Food Properties, 2014) Adu-Kwarteng, E.; Sakyi-Dawson, E.O.; Ayernor, G.S.; Truong, V.-D.; Shih, F.F.; Daigle, K.Total soluble sugar content and composition was studied by high performance liquid chromatography in four high dry-matter sweet potato cultivars at 3, 4, and 5 months maturity. Total soluble sugar consisted of sucrose, glucose, and fructose, ranging from 4.10-10.82 g/100 g (dry-weight basis). At harvest, there were significant differences in total soluble sugar due to maturity (p < 0.001) and cultivar (p < 0.05). The highest total soluble sugar contents were in 5-month samples at harvest (7.36-10.34 g/100 g) and 4-month samples after short-term storage under tropical ambient conditions (8.66-10.82 g/100 g). Estimated amylase enzyme activity varied significantly with harvest age (p < 0.05). Although reducing sugar contents were low, fructose levels in 5-month samples increased considerably after storage. © 2014 Copyright Taylor and Francis Group, LLC.