Listeria monocytogenes, a food-borne pathogen often found in milk and milk products, causes listeriosis in pregnant women, newborns, elderly and immuno-suppressed people. There have been reports on survival of Listeria in various milk products in the world, but comparable studies on the survival of Listeria in buffalo curd have not been reported. Therefore, the present study investigated the effects of fermenting buffalo milk and acidity on survival kinetics of L. monocytogenes. L. monocytogenes FSTLC2 and lactic acid starter cultures were aseptically introduced to boiled and cooled buffalo milk (fat 6%, protein 4%) and the mix was allowed to ferment at ambient temperature (26 ± 2 o C) for 18h. The Listeria count on Modified Oxford Agar (MOX; Oxoid Ltd.), lactic acid bacteria count on MRS Agar (Oxoid Ltd.), pH and titratable acidity were determined in the beginning and at 2h intervals during fermentation. The effect of pH/acidity on Listeria was determined by introducing Listeria to buffalo milk with pH values (pH 4.0, 4.5, 5.0, 5.5) adjusted using 88% lactic acid (BDH Chemicals) and enumerating Listeria on MOX Agar at 12h intervals for 96h. It was observed in the present study that Listeria count decreased over time and after 16h of fermentation of buffalo milk at ambient temperature, Listeria cannot be detected on MOX Agar. The pH value decreased from 6.8 to 4.1 and titratable acidity (lactic acid %) increased from 0% to 1.2 % during fermentation. Fermentation appeared to be an effective preservation technique in eliminating Listeria in buffalo curd. The pH value of 5.5 appeared to be the critical pH for inactivation of Listeria as no growth of Listeria was observed below pH 5.5. The total inactivation of Listeria in buffalo milk appeared to be due to lowering of pH coupled with increasing titratable acidity as well as action of bacteriocins, especially Nisin, produced by lactic acid bacteria during fermentation. It is clear that fermentation is an effective tool in inactivating Listeria in buffalo milk.
Low value addition, quality and price variations have been recognized as common problems of value chains in developing countries. Objective of the present study was to examine the quality and price variations throughout the dairy value chain in a less developed region in Sri Lanka. Wellawaya divisional secretariat of Monaragala district was purposively selected as the study area. Primary data were collected by using pre-tested, structured questionnaires. Laboratory tests of milk and curd samples were carried out to check the quality variation using standard methods. Milk samples were collected from three levels including farmer (10), processor (10 from each, milk and curd) and retailer (10) to determine the quality variation. According to the results, price of curd and yoghurt at consumer level was increased by 36% and 77% compared to the farm gate price. Farmer received the highest profit per liter of milk (68.00 LKR) in the shortest value chain (D) out of four main chains identified. The markets’ margin was estimated at 36%. Farmer had the largest share of 64% followed by processor (20%), retailer (8%), collector (4%), and wholesaler (4%). It was evident that farmers received fair profit through all four dairy value chains. However, solid non-fat percentage, specific gravity and pH of analyzed samples through the value chain were not comply with the standards. In conclusion, the prices of dairy products have increased while deteriorating the quality along the chain. It is therefore important to educate and train actors throughout the dairy value chain on quality management.
Value chain management is immensely important to the management of a network of interconnected businesses involved in the eventual provision of the highest quality product and service packages required by end customers. Dairy and dairy products are highly attached by microorganisms and products are damaged due to inappropriate methods of packing, storage and transportation. Insufficient information flow; low productivity, low GDP contribution from the dairy sector; poor processing capacity and lack of chilling centers are other major handicaps. Therefore, this study aimed: to assess the different quality maintenance practices for developing a Product Quality Index (PQI) for a dairy product and to make suggestions for improving quality through the quality index of the dairy value chain. Wellawaya Divisional Secretariat (DS) division was purposively selected out of 11 DS divisions of the district for the study since dairy production is the main occupation in that area. Stratified random sampling method was used to select 20 small scales, 10 medium scales, and 10 large scale farmers while the purposive sampling method was used to select, 10 collectors, 10 processors, 15 marketers and 15 consumers. Primary data were collected using a pre-tested structured questionnaire through a field survey. The PQI was developed for this study which is varied from 1 to 100 values. The result showed that all the practices in the Wellawaya area were shown medium standard based upon the mean marks. Animal nutrition management (6.0) was the best practice and farmer level hygienic and quality practices (3.45) were the practices with lower marks in the area. PQI of locally produced different dairy products were compared with the most popular dairy brand available on the market. According to the newly developed PQI value for this study, locally produce curd and yoghurts marks were varied from 29.5% to 64.6% and the PQI of the most popular branded curd and yoghurt products was 77.8%. So, locally produced curd and yoghurt products which are produced at the Wellawaya belong to medium and low-quality levels whereas the quality of the branded dairy products was high. In conclusion, it can be sid that Hence we concluded that the quality standard of locally produced dairy products were low as compared to branded dairy products. Therefore, it's important to train actors in the value chain to develop products with high-quality practices and suggests expanding the PQI value as an indicator for the quality of the dairy value chain.
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