Browsing by Author "Perera, M.N.P."
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Item Effect of Different Pasteurization Temperature – Time Combinations on Shelf Life of Raw Cream in Relation to its Microbiological, Chemical and Physical properties(Uva Wellassa University of Srilanka, 2011) Gunawardana, C.N.P.; Mudannayake, D.C.; Perera, M.N.P.Note: See the PDF Version Cream is a vital ingredient in manufacturing of many dairy products. Cream is a good substrate for microbial growth due to its high nutritional value. Generally, in dairy processing factories separated cream is held on a period of time prior to incorporation in to the dairy products. The spoilage of cream from separation till the production of dairy products has been a critical problem to producers. The treatments which are given and the conditions under which cream is held will have a direct effect on its keeping quality. Shelf life of raw cream currently produced as an ingredient for curd production at Fonterra Brands Lanka (Pvt) Ltd is estimated to be approximately four days at 4 °C. Therefore a method that could be used to extend the keeping quality of raw cream beyond four days would be a helpful and economical to the industry. Pasteurization of raw cream after separation can be done to improve the keeping quality. As there are no regulations governing heat treatment of cream in Sri Lanka, the time/temperature combinations used vary widely in practice. This investigation was undertaken to determine the effective pasteurization temperature/time combinations to improve the keeping quality of cream.Item Evaluation of Different Culture Types and Development of a Set Yoghurt With Cost Optimized Culture Option(Uva Wellassa University of Srilanka, 2011) Padmaraja, S.A.V.; Abesinghe, A.M.N.L.; Mudannayake, D.C.; Perera, M.N.P.NOTE: see the PDF version Over the last decade yoghurt and its preparations have developed into one of the most well-accepted and consumed acidified products. Mild acidic tastes, good digestibility, variations in taste and high dietetic value as well as stable quality have contributed to this growth. The starter culture is a critical factor in the production of set yoghurts it influences the organoleptic properties of the set yoghurt. A few studies have been conducted on evaluating the potential of using different culture types for yoghurt production. Kumari (2001) reported about the selection of a starter culture to improve the texture of plain set yoghurt at reduced total solid levels. Wijesinghe (1997) tested production of yoghurts using different ratios of Streptococcus therniophilllus and Lactobacillus bulgaricus and found that the best ratio of Streptococcus thermophilllus and Lactobacillus bulgaricus is 1:1. This study was carried out in one of the dairy factory in Sri Lanka where probiotic yoghurts are produced using two imported yoghurt starter culture types as base culture and probiotic culture. Base culture includes S. thermophilllus , L. bulgaricus and Bifidobacterium species. From these three species, first two are considered as authentic yoghurt starter bacteria whereas the other is a probiotic bacterium. Probiotic culture includes Bifidobacterium lactic. The viable bacteria count in probiotic yoghurts at the end of shelf life is 106 cfu mL-I However, it was found that the probiotic bacteria in base culture do not contribute much to maintain the viable probiotic bacterial population in set yoghurt. Therefore, the main objective of this study was to select a suitable non- probiotic base culture for the existing set yoghurt without changing its organoleptic properties and thereby optimize the cost of set yoghurt production by selecting suitable non-probiotic base culture.Item Selecting Low Cost Freeze Dried Culture for Curd to Replace Existing Starter Culture(Uva Wellassa University of Sri Lanka, 2013) De Silva, J.H.I.G.; Abesinghe, A.M.N.L.; Perera, M.N.P.Curd is a thick, sour, well known fermented milk product having close resemblance to yoghurt. It has a distinct taste, richness and delicacy. It is not only refreshing and delicious but nutritious, healthy and easily digestible. Curd is an integral part of Indian diet and possesses therapeutic and dietetic properties (Gupta and Prasad, 2000). Curd is also known as probiotic or functional food as it possesses live lactic acid bacteria. Benefits of consuming curd are; enhanced immune response, balancing of fecal enzymes and intestinal micro flora, prevention of cancer, antibiotic therapy, reduction of serum cholesterol and risk of coronary heart diseases, antagonism against food borne pathogen, tooth decay organism and anti-tumor activity (Pattnaik and Mohapatra, 2000). Bacterial cultures, known as starters are used in manufacturing of curd, yoghurt, kefir and other cultured milk. The starter is added to the product and allowed to grow there under controlled conditions. During fermentation, bacteria produce substances which give the cultured product its characteristic properties such as acidity, flavour, aroma and consistency. Drop in pH, which takes place when the bacteria fermenting lactose to lactic acid, has a preservative effect on the product, while at the same time the nutritional value and digestibility are improved (Rubiga Sivapatham, 2001). Dairy starter cultures are carefully selected microorganisms, which are deliberately added to milk to initiate and carry out desired fermentation under controlled conditions. Most of them belong to lactic acid bacteria (Lactococcus, Lactobacillus, Streptococcus and Leuconostocs).The different starter used in the manufacture of curd includes Lactococcus. lactis, L. cremoris, Streptococcus thermophilus, Lactobacillus bulgaricus, L. plantarum and lactose fermenting yeasts. The main objective of this study was to select a most cost optimized starter culture to replace the existing composite starter cultures, without changing its organoleptic properties. Methodology Curds were prepared according to the standard procedure (SLS part 2:1989). Two starter cultures were used (A and B) which were lower in cost than the existing starter culture. Organoleptic characteristics of curds prepared with A and B were compared with the curd thermophilus, Lactobacillus delbrueckii subsp. Bulgaricus and Bifidobacterium species and culture type “B” and Streptococus lactis subsp. lactis biova diacetylactis. Completely Randomized Design (CRD) comprising three treatments with four replicates was used as the experimental design. Parametric data analysis was done using ANOVA for significance under α = 0.05 level using MINITAB 15 statistical software package. Non parametric data analysis was done by Friedman non-parametric test using MINITAB 15 statistical software package. The sensory evaluation was carried out with seven trained panelists and 23 untrained panelists using nine point hedonic scale to assess sensory attributes of appearance, flavour, texture, mouth feel and overall acceptability. Shelf life of the curd prepared was determined by analyzing titratable acidity, pH, yeasts and moulds, coliforms at five days intervals for 35 days and compared with the control. Results and Discussion According to the figure 1 there was no significant difference between sensory attributes of appearance, flavour, texture, mouth feel and overall acceptability of “A”, “B” with the control (P>0.05). However, curd prepared with culture type “A” was rejected due to prolong setting time compared to control. Culture type “B” was selected as the most cost optimized starter culture which gives similar properties and used for further analysis.