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ThesisItem Open Access PREPARATION OF MOZZARELLA CHEESE USING SKIM MILK FILLED WITH COCONUT MILK(COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR, 1994) GNANA SELVA JOHNSON; M. MUKUNDANA detailed study was carried out to determine the quality of coconut fat filled milk for the preparation of Mozzarella cheese and whey drinks. Literatures based on filled milk products has been reviewed, apart from the preparation of cheese and whey drinks. The control samples of Mozzarella cheese and whey drinks were prepared using cow's milk. Experiment I products were prepared from milk in which 50 per cent of milk fat was replaced with coconut fat. Experiment II products were prepared from cheese milk in which 100 per; cent of milk fat was replaced with coconut fat. All the samples of milk were standardized to 4 per cent fat. A total of 6 trials were carried out to obtain reliable data for statistical analysis. The acidity, pH, stretchability and EDM content were found to be similar in control, experiment I and II Mozzarella cheese. Eventhough, the control Mozzarella cheese were found to have slightly higher yield, protein, fat and lower moisture content, the experiment I and II. Mozzarella cheese also satisfied the requirements for good quality Mozzarella cheese. The control Mozzarella cheese got maximum score on sensory evaluation than the experiment I and II Mozzarella cheese. Pineapple and Lemon flavoured control, experiment I and II whey drinks were found to be equally acceptable with no difference on storage studies ar 5+1oC. Total bacterial count on whey drinks were also made. The studies revealed that the cow milk in which the milk fat replaced to the extend of 50 per cent and 100 per cent with coconut fat can be effectively utilized for preparation of Mozzarella cheese. The quality of such cheese is comparable with that made from cow milk.ThesisItem Open Access Lactobacillus acidophilus as a dietary adjunct in Dahi and Yogurt(COLLEGE OF VETERINARY AND ANIMAL SCIENCE,MANNUTHY, 1995) APPALO ELEVEN, S; Prasad, VAn experiment was conducted to study the beneficial effect of incorporating L. acidophilus in dahi and yogurt as a dietary adjunct. An attempt was also made to find out the bile tolerance of L. acidophilus and other lactic acid bacteria. An exhaustive review of literature has been presented on the issues of lactose intolerance and hypercholesteremia and the beneficial effects of lactic acid bacteria in alleviating these drawbacks/ with a special emphasis on bile tolerance and intestinal colonisation. The methods of analysis of some important components of dahi and yogurt have been detailed. Treatment dahi was prepared by inoculation with L. acidophilus in addition to normal dahi cultures. This was compared with control dahi prepared with normal cultures alone. Treatment yogurt was prepared with inoculating L. acidophilus along with normal yogurt cultures. This was compared with control yogurt prepared using normal yogurt cultures. The samples were then analysed for various parameters. There was an increase in the ^-galactosidase specific activity of treatment dahi when compared to the control dahi. But in the case of yogurt, the treatment yogurt was having a low ^-galactosidase specific activity when compared to the control yogurt. Control dahi showed inhibition against E. aerogenous, M. falvous, E. coli and aureus. It did not showed any inhibition against B. cereus. Treatment dahi exerted a significantly high inhibition zone against all the test organisms in comparison to control dahi. Control yogurt inhibited only E. aerogenous and coli. Treatment yogurt exerted a significantly high antibacterial activity against all the organisms tested. Of, all the lactic acid bacteria tested for their ability to grow in the presence of 0.3 per cent of Oxgall, only L. acidophilus grew satisfactorily. L. delbrueckii ssp bulqaricus showed a poor growth, whereas salivarius ssp thermophilus Lac. lactis and Lac. lactis ssp diacetylactis failed to grow in the presence of Oxgall. Both the dahi and yogurt treatments showed higher hypocholesteremia when compared to their respective controls. The total serum cholesterol level, serum triglyceride, LDLCholesterol and cardiac risk factor of the treatment groups were significantly lower than the respective controls. The HDL-Cholesterol was high in both the treatments when compared to the respective controls. The growth rate of treatment dahi group was low when compared to the control dahi group. But the treatment yogurt group showed a higher growth rate as compared to the rats fed on control yogurt. From the above study the following ' conclusions were made. 1. The incorporation of L. acidophilus in dahi, increases its ^-galactosidase specific activity. However, in yogurt it resulted in a decreased ^-galactosidase specific activity when compared to normal yogurt. 2. In both dahi and yogurt, the incorporation of L. acidophilus resulted in an elevated antibacterial activity against E. aerogenous, M. falvous, E. coli, aureus and B. cereus. 3. L. acidophilus was able to grow satisfactorily in the presence of Oxgall. While the other lactic acid bacteria tested either showed a poor growth or no growth at all in the presence of Oxgall. 4. Rats fed with dahi and yogurt incorporated with L. acidophilus showed a lower serum total cholesterol, serum triglyceride, and LDL-Cholesterol levels, when compared to the control groups. 5. The HDL-Cholesterol level was high in both the treatment dahi and treatment yogurt fed rat groups. 6. The treatment dahi and treatment yogurt fed rats showed a significant decrease in the cardiac risk factor when compared to their respective controls. 7. The treatment dahi showed a lower growth rate, and treatment yogurt showed a high growth rate when compared to their controls.ThesisItem Open Access EFFECT OF PRESERVATIVES ON MILK SOLIDS IN COW AND BUFFALO MILK(COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR, 2001) RADHA, K.; Sathian, C.T.Pooled milk samples were collected from cow and buffaloes maintained at the University Livestock Farm at weekly intervals. Three chemical preservatives viz., formalin (0.4 per cent), potassium dichromate (0.4 per cent) and bronopol (0.1 per cent) were studied for their efficiency of preservation. Calculated levels of preservatives were added and the samples were stored at room temperature in dark place. Major milk constituents like fat, total solids and solids not fat were estimated in control and preserved samples. Physical properties of milk such as pH, titratable acidity, clot on boiling test, lactometer reading as well as efficiency of preservation were studied in control and preserved milk samples. Milk samples treated with formalin could be stored up to 90 days without any spoilage changes. A cream plug formed after 24 hours of storage and a white sedimentation at the bottom appeared after one month of storage. Potassium dichromate treated samples could be stored for 30 days. There after the samples curdled and became green in colour towards the end of the storage period. 11 Bronopol preserved cow and buffalo milk samples could be stored for 24 and 16 days respectively and samples became mild pink in colour as the storage period advanced. There was a significant increase in titratable acidity in cow and buffalo milk samples preserved with all the three chemical preservatives. The increase in acidity was steady and progressive in formalin and bronopol preserved samples. But an abrupt increase in acidity was noticed in potassium dichromate preserved samples immediately after the addition of preservative and there after a successive decrease was noticed. The pH values showed a significant decline during storage in preserved milk samples. Decline in pH was abrupt in potassium dichromate treated samples whereas it was gradual in samples treated with the other two preservatives. Formalin treated milk samples remained COB negative throughout the storage period of 90 days, whereas potassium dichromate and bronopol treated samples became COB positive after 15 and eight days of storage respectively. No significant variation was noticed in fat percentage of preserved milk samples estimated by Gerber method. But a slight decrease in fat per cent was observed in formalin and Ill potassium dichromate treated samples. The concentration of Sulphuric acid used was increased to 94 per cent for estimating fat percentage in formalin preserved milk samples. Formalin preserved samples showed inconsistent changes in fat percentage estimated by Milko-Tester. So this method cannot be recommended for formalin preserved milk samples. Bronopol treated milk samples showed lesser variation in milk fat percentage estimated by Milko-Tester when compared to potassium dichromate and formalin. There was a non-significant increase in total solids and solids not fat content in potassium dichromate preserved samples. Potassium dichromate preserved samples showed significant increase in lactometer reading, where as formalin and bronopol treated samples did not show any significant changes in lactometer reading. Formeilin appears to be ideal for the existing standard methods of estimating milk solids. With the popularization of instrumental methods for fast and accurate analysis of milk constituents, formalin will not be suitable as a milk sample preservative in future. Further, formalin and potassium dichromate have deleterious effects on human health and environment. Even though bronopol is little expensive, it is best suited for instrumental analysis of milk constituents and safe for handlers. So, bronopol is recommended as a preservative for the near future.ThesisItem Open Access ISOLATION AND CHARACTERIZATIONOF ANGIOTENSIN CONVERTING ENZYME INHIBITORY PEPTIDES FROM FERMENTED GOAT MILK(COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR, 2017) SATHYA, P.; Radha, K.A study was conducted to isolate and characterize the angiotensin converting enzyme (ACE) inhibitory peptides from fermented goat milk and to compare the potential of selected lactic acid bacterial cultures for the release of angiotensin converting enzyme inhibitory peptides. Goat milk was fermented by using 14 different lactic acid bacterial cultures at three and four per cent inoculum levels. Fermented goat milk samples were analysed for pH, titratable acidity, lactic acid bacterial count, proteolytic activity and ACE inhibitory activity. The results showed that pH, titratable acidity, lactic acid bacterial count, proteolytic activity and ACE inhibitory activity varied significantly (p≤0.01) among milk samples fermented with different lactic acid bacterial cultures. The highest ACE inhibitory activity was observed in milk fermented with L. plantarum 379 (97.558 ± 0.965)at four per cent inoculum level. The lowest ACE inhibitory activity was observed in milk fermented with L. helveticus288(65.121± 0.963) at three per cent inoculum level. The corresponding IC50 values were 0.018 and 0.082 mg/ml. A positive correlation between proteolytic activity and ACE inhibitory activity was observed in milk samples fermented with L. helveticus 192, L. bulgaricus 009, L. plantarum 379 and L. casei 017. There was also a positive correlation between inoculum level and ACE inhibitory activity in milk samples fermented with L. helveticus 192, L. rhamnosus 024 and L.acidophilus (015 & 298).Among the 14 fermented milk samples, six samples (L. plantarum379 and 417, L. rhamnosus8712, L. acidophilus 10307, L.helveticus288 and L. bulgaricus009) with high ACE inhibitory activity were selected and peptides were separated by gel filtration column chromatography. Isolation of ACE inhibitory peptide was done by reverse phase high performance liquid chromatography. Characterization of ACE inhibitory peptide was done by Tristricine SDS PAGE which showed that the molecular weight of the identified peptide was 1.4 kDa.ThesisItem Open Access IMPACT OF SOMATIC CELL COUNT ON PHYSICOCHEMICAL QUALITY OF MILK AND FERMENTED MILK PRODUCTS(COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR, 2016) ANU JOSEPH, PEREKATTU; T.SATHIAN, C.Objectives of the research work were to find out the impact of somatic cell count (SCC) on the physicochemical properties of milk and on the quality of fermented dairy products, curd and yoghurt. The correlation between the somatic cell count and total DNA content isolated from the milk was also explored. In this study one hundred pooled cow milk samples were collected from farms and milk co-operative societies in Thrissur district. The samples were categorised into three groups based on SCC into low, intermediate and high. All the pooled cow milk samples were subjected to Methylene Blue Reduction Test, isolation and quantification of DNA. Somatic cell count, pH, titratable acidity, chloride content, and electrical conductivity of the samples were estimated. On analysis, it was found that pH showed a negative correlation and titratable acidity showed a positive correlation with high SCC category milk. Chloride content as well as electrical conductivity of milk showed a significant positive correlation (P< 0.01) with SCC in milk. An elevated somatic cell count in milk was associated with poor microbial quality of raw milk revealed by Methylene Blue Reduction Test. Pearson’s analysis showed a significant positive correlation (P<0.01) between the DNA yields extracted from the pooled cow milk and the milk Somatic cell count. Yoghurt and curd prepared from milk with varying SCC (low, intermediate and high) were evaluated for the starter activity, free fatty acid content, viscosity and sensory evaluation. The free fatty acid content of the high SCC yoghurt and curd were significantly higher than the low SCC yoghurt and curd (P<0.05). Starter activity of high SCC yoghurt was significantly lower (P<0.05) than the low and intermediate SCC yoghurt, while the starter activity of curd showed no difference among the three groups (P>0.05). Sensory evaluation of the products revealed that there was a negative correlation (P<0.05) between the sensory scores and SCC of milk. It was concluded that the milk with SCC greater than 5x105cells/ml had negative impact on the quality of milk and milk products. Estimation of DNA content of milk will provide a good technique for enumeration of SCC in milk.ThesisItem Open Access EFFECT OF NISIN ON THE KEEPING QUALITY OF Dahi(COLLEGE OF VETERINARY AND ANIMAL SCIENCES Mannuthy - Thrissur, 1992-09-28) SREEJA RAMACHANDRAN; Prasad, V.An experiment was conducted to find out the effect of preservatives such as nisin and potassium sorbate on the keeping quality of dahi. An attempt was also made to study the quality of dahi produced under household conditions with a special emphasis on the maintenance of starter. An exhaustive review of literature has been presented on the use of various preservatives in dahi, keeping quality and other related aspects. The methods of analysis of some important components of dahi has been detailed. Dahi was prepared under laboratory conditions (Method I) and under household conditions (Method II). Both were divided into four parts and applied four treatments namely (1) Treatment A - with 1000 lU nisin/i^ g curd (2) Treatment B - with 10 ml of nisin producing organism capable of producing 1000 lU of nisin/100 g curd (3) Treatment C with 0.2 per cent potassium sorbate (4) Treatment D - Dahi stored as such without any treatments. All treatments were compared with dahi at 0 hour (control). The dahi after treatments A, B, C and D from methods I and II were mixed well and transferred to 100 ml cups and stored at room temperature. Samples from each treatment were subjected to chemical, microbiological and organoleptic evaluation on the 2nd, 3rd, 4th, 7th, 10th and 21st day of storage for acidity, pH, lipolysis, proteolysis, diacetyl, total lactic count, coliform count and yeast and mould count. There was a decrease in acidity for all treatments from the initial level under method I. Whereas acidity was maintained to the initial level under method II. There was only a slight change in pH during different periods of storage for all the treatments under both methods. Proteolysis of dahi remained to the initial level upto 24 hours then increased gradually under both methods. Tyrosine value was higher under household conditions which could be due to the presence of proteolytic bacteria other than starter organisms that have gained entry into dahi through starter culture. An abrupt reduction in diacetyl contents was noticed in dahi during storage. This could be due to the reduction of diacetyl by the enzyme diacetyl reductase produced by certain streptococci. With regard to the free fatty acid content treatments A, B and C were effective in controlling the breakdown of fat during storage. Addition of nisin did not alter the total lactic count and it was maintained to initial level even after storage for 4 days. Nisin producing organisms multiplied during storage. In potassium sorbate added dahi a reduction in lactic count was noticed probably due to depletion of nutrients rather than the direct effect. Growth and multiplication of yeast, mould and coliforms were controlled in both methods by nisin or nisin producing organisms in dahi. Potassium sorbate completely eliminated yeast and mould and coliform growth in dahi but it reduced flavour score during sensory evaluation. Sli., From the above findings it was concluded that the lowacidity produced on storage might be due to the fact that the lactic acid bacteria added were low acid producers. There was a reduction in flavour score for potassium sorbate added dahi but at the same time it was found to suppress the yeast and mould growth completely. Hence it is recommended that potassium sorbate preferably at a reduced level of 0.1 per cent along with nisin producing organisms can keep up the quality of dahi under room temperature. Also it is advisable to change the culture at least once a week to get good quality dahi with characteristic diacetyl flavour under household conditions.ThesisItem Open Access EFFECT OF FEEDING ADDITIVES ON TOTAL SOLIDS OF COWS' MILK(COLLEGE OF VETERINARY AND ANIMAL SCIENCES Mannuthy - Thrissur, 1992-08-31) SATHIAN, C. T; FRANCIS, U.T