Use of Locally available materials in the development of culture media for the production of Cheese starter cultures in Zambia

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Nkhata, Greyson Lyson Elemson
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To determine which farms around Lusaka produce Cheese, a questionnaire was prepared and dispersed to dairy farms affiliated to the Zambia National Farmers Union (ZNFU) around Lusaka.The Dairy Produce Board of Zambia (DPBZ),Pebble Brook Cheese Factory (PBCF) and Kaposhi Cheese Factory (KCF) were visited and modes of cheese processing studied.Lyophilized stock cultures obtained from KCF,ZA de Buxiers BP10 of France and a mother culture from DPBZ were used as principal organisms to test the efficacy and sensitivity of all media used in this study. Eight complex broth media were constructed in the preliminary study. Carbon, nitrogen and growth factors (organic and inorganic)sources varied both quantitatively and qualitatively. Buffering chemicals, distilled water, and sodium chloride were kept constant in amounts of the media dispensed in 250 ml. Pyrex conical flasks cotton wool plugged. They were sterilized by autoclaving (120CC, 15 min, 0.41Kg/cm ) and inoculated with a lyophilized starter culture prior to its activation in pasteurized DPBZ milk. Based on absorbance readings and total colony counts, the quality of media beginning with the optimal was found to be in the following order:MiIk(Mil) —> Soya flour, Orange, Yeast(Soy)—>Whey, Irish potato, Pumpkin (Wip) —> Carrot, Ammonium phosphate (Cap) —> Milk, Glucose (Mig) —>Brown wheat flour, Ammonium phoshate, Sucrose (Bas) —> Meat, Sugarcane, Tomato (Mst) —> Maize bran, Beans,Lettuce (Mbl). Further experiments to estimate the optimal concentrations of ingredients to the growth and propagation of the lactic bacteria were conducted with Mil, Soy, Wip and Cap media.Lactic bacteria cultivated in Mil, Soy and Za de Buxiers BP10 lyophilized culture were activated in skimmed milk and used to produce six samples of Cream cheese at PBCF. The cheese samples were analysed to compare acidity, moisture and fat content at National Council for Scientific Research (NCSR).Significant findings in this study are that local raw materials (milk, soya flour, orange Juice, yeast, whey, irish potatoes, pumpkin leaves, meatbroth, carrot, brown wheat flour, beans and lettuce)can be used to grow and propagate cheese starter cultures. This subculturing technique, when understood and effectively used by the Zambian cheese producers,will help reduce cheese production costs.