Characterization of the dominant microorganisms responsible for the fermentation of dehulled maize grains into nsiho in Ghana

Nsiho (white kenkey) is a type of kenkey, a sour stiff dumpling, produced from fermented maize meal in Ghana. The dominant microorganisms responsible for the fermentation of nsiho were characterized by analysing samples from four traditional production sites at Anum in the Eastern Region of Ghana. During 48 h of steeping dehulled maize grains, the pH values decreased from 6.05 to 5.93 to 3.59 to 3.55, whilst titratable acidity increased from 0.02 to 0.03 to 0.27 to 0.32%. In the subsequent 12 h dough fermentation, the pH decreased from 6.02 to 5.80 to 3.52 to 3.46, whilst titratable acidity increased from 0.25 to 0.27 to 0.35 to 0.38%. The lactic acid bacteria population increased by 2 to 5 log units to concentrations of 107 to 108 CFU/ml during steeping and by 2 to 3 log units from 105 to 106 CFU/g to 108 to 109 CFU/g during dough fermentation. Yeasts counts increased by 3 to 4 log units during steepingand by 2 to 4 log units during dough fermentation. The most frequently isolated lactic acid bacteria responsible for nsiho fermentation were identified as Lactobacillus fermentum (47.1%), Lactobacillus brevis (25%), Lactobacillus plantarum (14.42%), Pediococcus pentosaceus (8.65%) and Pediococcus acidilactici, (4.8%). The dominant yeasts species were Saccharyomyces cerevisiae (47.6%), Candida krusei (29.1%),  Debaryomyces spp., (15%) and Trichosporon spp., (8.3%). This is the first  study to report on the micororganisms involved in nsiho fermentation.Key words: Nsiho, dehulled maize, kenkey, lactic acid bacteria, indigenous African fermented foods

Effects of cowpea fortification and the level of ripeness of plantain on the nutritive value of plantain based snack foods

To investigate effects of cowpea addition and level of ripeness of plantain on the nutritional and sensory characteristics of Kaklo and Ofam in Ghana, A 2X4 factorial experiment with firm and soft ripe plantain and cowpea fortification of 0, 10, 20 and 30% was designed. The proximate composition and acceptability of products using a 7-point hedonic scale were evaluated. With the addition of 30% cowpea, the protein content of the Kaklo from the firm ripe and soft ripe plantain increased from 2.92% to 7.32% and 3.65% to 8.05% respectively, whilst the protein of the Ofam from the firm and soft ripe plantain also increased from 3.80% to 8.45% and 3.75% to 8.15% respectively. The 10% fortified Kaklo and Ofam werethe most acceptable. The cowpea addition significantly affected the nutritional value of the Kaklo and Ofam. To obtain an acceptable cowpea fortified plantain-based snack, the fortification should be done at10%

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

Volatile compounds of maari, a fermented product from baobab (Adansonia digitata L.) seeds

The volatile compounds associated with baobab seeds fermentation for Maari production were extracted and analysed by Likens-Nickerson simultaneous steam distillation-extraction method and gas chromatography-mass spectrometry (GC-MS), respectively. Furthermore, the titratable acidity, tannin content and proximate composition were evaluated. A total of 96 compounds were identified with esters, acids, alcohols and ketones being quantitatively the major groups. Fermentation led to an increase in the concentration of total volatile compounds from 121.6 in unfermented cooked seeds to 809.1 mg kg-1 in the fermented product. Drying resulted in a significant loss of up to 80.7% of the total volatiles.Key words: Volatile compounds, maari, baobab, fermentation