Browsing by Author "Heita, Lusia"

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    Antimicrobial activity profiles of traditional fermented milk starter culture from north-eastern Namibia
    (2014) Heita, Lusia
    The aim of this study was to identify and examine the antimicrobial properties of Lactic Acid Bacteria (LAB) isolated from fermented milk collected from Ohangwena, Omusati, Oshana, Oshikoto, Zambezi and Kavango regions. Traditional fermented milk in Namibia are produced by spontaneous fermentation using traditional utensils. In this study, thirty homesteads from six regions that produce and process fermented milk were selected and interviewed using semi- structured questionnaires. Omashikwa and Mashini ghakushika have similar processing method whereby fermentation is achieved by accumulation of milk; mean while Mabisi is produced by allowing the milk to ferment naturally. The pH decreased logarithmically, nonlinearly over the fermentation period from 6.5 ± 0002 from first day of fermentation to 3.92±0.001 over 4 days.There was no significant difference (p<0.05) in the pH values between the three types of fermented milk preparations. Cell free supernatants (CFS) of 180 LAB isolated from traditional fermented milk were evaluated for antimicrobial activities against selected food borne pathogens; Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Candida albicans ATCC 14053, Bacillus cereus ATTC 10876 Geotrichum klebahnii (IKST F. Lab. isolate) Escherichia coli ATCC 25922 using the well diffusion method. Twenty LAB isolates that shown the highest inhibitory effects were selected for biochemical identification using API 50 CHL were identified as; Lactobacillus plantarum (53%), Lactobacillus rhamnosus (29%), Pediococcus pentosaceus (6 %), Lactobacillus paracasei ssp. paracasei (6%) and Lactococcus lactic ssp. lactis (6%), of which Pediococus pentosaceus showed the most inhibitory effect on all the indicator strains and they have potential to produce bacteriocin Pediocin and the most inhibited indicator strain belonged to yeast Candida famata. In addition to antimicrobial activities, the major organic acids in all three types of milk were found to be lactic acid 0.265±0.056 mg/L. However, the levels of volatile organic compounds in the naturally fermented samples varied from one sample to another but, butyric, acetic and propionic acid were found in trace amounts. Some of the volatile flavor compounds found in Omashikwa, Mabisi and Mashini ghakushika were acetic acid, 2,3 Butanediol and Lactic acid. Further genetic confirmation of species was carried out using the 16S rDNA sequences. The research outcome addressed the establishment of the newly identified starter cultures and contributes positively to the advancement of national LAB’s profiling. The study is also the first attempt that indicates probiotic potential and exceptional preservation properties of LAB from traditional fermented milk produced in North- Eastern Namibia.
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    Dominant lactic acid bacteria and their antimicrobial profile from three fermented milk products from northern Namibia
    (2014) Heita, Lusia; Cheikhyoussef, Ahmad
    The present study focused on the isolation, identification and antimicrobial profile of the dominant lactic acid bacteria from three traditional fermented milk products namely: Omashikwa, Mabisi and Mashini Ghamushikwa from the north-central and north-eastern parts of Namibia. The microbiological and antimicrobial activities of these products fluctuate from one region to another depending on the local indigenous microflora. Omashikwa and Mashini Ghamushikwa fermentation processes involves the addition of Boscia albitrunca root (Omunkuzi) and butter churning. The root contributes to the flavor of the product, increasing the milk fermentation rate and churning. Mabisi is produced by letting the milk to ferment naturally until the water is separated from the whey. The water is then decanted, and the whey is shaken until it is smooth without removal of fat. A total of 180 isolates of Lactic acid bacteria (LAB) were obtained and identified based on their phenotypical characterization. Cell free supernatants (CFS) of the 180 LAB isolates were evaluated for antimicrobial activities against selected food borne pathogens; Escherichia coli ATCC 25,922, Staphylococcus aureus ATCC 25,923, Bacillus cereus ATTC 10,876, Candida famata and Geotrichum klebahnii using the well diffusion assay. Twenty LAB isolates having the highest inhibitory effects were selected for biochemical identification using API 50 kit and these were identified as being; Lactobacillus plantarum (53%), Lactobacillus rhamnosus (29%), Pediococcus pentosaceus (6%), Lactobacillus paracasei ssp. paracasei (6%) and Lactococcus lactic ssp. lactis (6%). Pediococcus pentosaceus showed the highest inhibitory effect on all the indicator strains. This study provides an insight into LAB diversity of unstudied Namibian fermented milk products and reports a potential production of antimicrobial compounds which is significant in the standardization of protective starter cultures which can be used to control fermentation process and shelf life extension of dairy products in Namibia.
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    Study on fermented milk (Omashikwa) in northern Namibia (Ohangwena, Oshana, Oshikoto and Omusati) regions
    (2012) Heita, Lusia; Cheikhyoussef, Ahmad
    EXECUTIVE SUMMARY: Traditional fermented milk products are widely consumed in the entire world. These products are an important supplement to the local diet and provide vital elements for growth, good health and an appreciate flavor. In Namibia there are many types of fermented milk which are commonly eaten by local people. This study focused on Omashikwa which is the traditional fermented milk of Oshiwambo speaking people and mostly found in four regions Ohangwena, Oshikoto, Oshana and Oshikoto. The purpose of this study was to collect fermented milk samples and to document the processing and the house hold preservation methods of Omashikwa. The samples collected will be used to examine the antimicrobial properties of Lactic Acid Bacteria or LAB isolates with potential probiotic use in order to control and eliminate the spread of harmful bacteria in food products. A total of 13 samples were collected and 13 questionnaires were filled in. The first region visited was Ohangwena region in which one village was surveyed, then Omusati region; three villages, Oshana four villages lastly Oshikoto only two villages. The pH of the samples was done in the field using a pH meter. The pH average ranged between 3.44 - 3.83. There was no significant difference in the house hold processing method of the Omashikwa among the Oshiwambo speaking people. Regarding the indigenous knowledge, all respondents indicated that the milk have social value as it act as a source of income to many. The milk has a very short shelf life of only seven to twelve days.
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    Study on indigenous fruits and ethnobotanical uses in Ohangwena and Oshikoto regions
    (2012) Cheikhyoussef, Ahmad; Embashu, Werner; Heita, Lusia; Potgieter, Sannette
    SUMMARY: Research into Indigenous Knowledge System Technology (IKST) has been receiving increasing attention from various research institutions and Government Ministries in Namibia during the last five years. Indigenous communities in Namibia possess a rich traditional knowledge expressed in many practices in their communities. Indigenous wild edible fruits are available within the Namibian 13 regions which provide a rich source of vitamins and fibres for indigenous people’s diet. The aims of this study were to record the different IKST practices on the indigenous fruit trees in Ohangwena and Oshikoto regions. Three constituencies in Ohangwena region were surveyed; these including Okongo, Eanhana and Ondobe Constituencies. In Oshikoto region; only one constituency which is Onayena was included in the survey. A total of 65 respondents were interviewed; 54% women, 38% men and 8% both in group interviews. The majority of the people interviewed were in their thirty’s, with the youngest being 18 years old and the oldest being 98 years old. Thirty eight plant specimens were collected of which 24 are from Ohangwena and 15 from Oshikoto region, these specimens belong to 18 genuses and 23 species. Regarding to the indigenous knowledge; most of the respondents indicated that their knowledge on indigenous fruits was learnt mainly through their parents. Almost all of the respondents reported that the indigenous fruits and their products have social values such as it is presented to guests at special ceremonies, weddings, etc. In addition to their social values; health values have been reported also especially with regard to has flu. Some people depend on these fruits and their by-products to get income, for example Distilled liquor from Eembe (Berchemia discolor), Palm fruits (common practice in Oshikoto region). Most of the peoples reported that the traditional beer and wines are the main products made from these fruits.
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    Traditionally fermented milk products
    (University of Namibia Press, 2015) Heita, Lusia; Cheikhyoussef, Ahmad
    Fermented milk is one of the foods that are highly respected and form a part of the daily intake in Namibia. There are many types of fermented milk in Namibia, which have different preparation methods. Milk fermentation assists in preserving the milk by generating organic acids (e.g., lactic and acetic acids) and antimicrobial compounds (e.g., bacteriocins), as well as flavour compounds (e.g., acetaldehyde) and other metabolites (e.g., exopolysaccharides) that contribute to the product’s organoleptic properties. Fermented milk provides special therapeutic and prophylacticbproperties against many diseases, symptoms and health problems. This chapter outlines the types of traditionally fermented milks produced in Namibia – omashikwa, mashini ghakushika and mabisi – their modes of fermentation and physicochemical properties, and the dominant microflora in them. The health and social benefits of these fermented milk products are also discussed