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ThesisItem Open Access Bacteriological quality of goat milk(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1985) Chakhesang, Kevesiei; KAU; Sukumaran, M VA total of 376 aseptically – drawn milk and 46 farm pooled milk samples were collected from the AICRP on Goats for Milk, Mannuthy and subjected to various tests to determine the bacteriological quality. An increase of over 59 and 188 – fold in bacterial number from aseptically – drawn milk to production – and milk for the morning and the evening milkings respectively was noticed. In aseptically – drawn milk samples 61.17% and 64.83% gave a SPC of below 100/ml in the morning and evening respectively. In farm pooled milk samples the SPC exceeded 105/ml in 39.13% of the morning and 65.22% of the evening samples. No psychrophilic bacteria was detected in any of the aseptically – drawn or farm pooled milk samples. The mean thermophilic counts of aseptically – drawn as well as farm pooled milk samples was less than one/ml. Though the mean coliform count of aseptically – drawn milk was found to be less than one/ml, the farm pooled milk samples showed 3,413 and 2734/ml for the morning and the evening samples respectively. The mean MBRT of the morning and the evening samples was 14.91 and 8.93 h for aseptically – drawn milk and 4.57 and 3.83 h for farm pooled milk samples respectively. The correlation coefficient between MBR time and SPC of farm pooled milk of the morning and evening samples was not significant (- 0.21 and - 0.27). The keeping quality of the morning and the evening milk samples (280 C) obtained was respectively 50.48 and 44.70 h for aseptically – drawn milk and 12.87 and 12.04 h for farm pooled milk samples respectively. The correlation coefficient between SPC and keeping quality of farm pooled milk samples was significant (- 0.46) for morning sample while that of evening milk was not significant (+ 0.28). The correlation coefficient between MBRT and keeping quality of farm pooled milk samples was also not significant in both the morning and the evening (+ 0.31 and + 0.13).ThesisItem Open Access Qualitative changes of yoghurt prepared from milk preserved by different methods(Department of Dairy Science, College of Veterinary and Animal Sciences,Mannuthy, 1990) Prasad, V; KAU; Sukumaran, M VAn experiment was conducted to study the qualitative changes of yoghurt prepared from milk preserved by different methods. An attempt was also made to study the efficiency of LP system in controlling psychrotrops in refrigerated milk thereby extending the keeping quality of such stored milk. The efficacy of the system was compared with pasteurized milk and raw milk stored under similar conditions. An exhaustive review of literature has been presented on the use of various preservation methods employed in milk, quality of yoghurt and other related aspects. The methods of analyses of some important components of milk and yoghurt has been detailed. The milk after collection were divided into three portions and used for various treatments A (raw milk as such), B (laboratory pasteurized) and C )LP activated). Samples in each treatment were again divided into four parts and stored under refrigeration for 0, 24, 48 and 72 hours for further analysis and yoghurt preparation. When raw milk was stored under refrigeration, acidity developed to a significantly high level (P < 0.05) at the end of 72 hours of storage whereas no significant increase in activity was noticed in treatments B and C. This result was corroborated by a decrease in both psychrotrophic and total bacterial counts in milk under treatments B and C. So it was concluded that the development of acidity in treatment A could be due to bultiplication of microbes particularly psychrotrophs. In B and C its growth was arrested by the treatments. Hydrogen peroxide and thiocyanate were detected in all raw milk samples at a level of 3.78 and 7.33 ppm respectively. The level of H2 O2 and SCN – used for the activation of LP system for the study were found to be adequate, since the psychrotrophic count in milk at the end of 72 hours in treatment C was less than that found in treatment B. The residual H2 O2 and SCN – contents at the end of 72 hours were found to be within the normal level found in milk thus having no health hazards, by this method of preservation. When yoghurt samples were prepared from stored milk no significant differences between treatments were noticed in the values of fermentation period, acidity, pH, total proteins and total solids. A significant increase in NPN and tyrosine values were noticed in yoghurt prepared from milk under treatment A indicating extensive proteolysis in milk during storage under this treatment. However, no difference was noticed between treatments B and C. Diacetyl and acetaldehyde were produced at a desirable level in yoghurt samples under all the three treatments. A proper ratio of Str. Thermophiles – 6 and L. bulgaricus – 4 was found to be maintained in all yoghurt samples. On organoleptic evaluation the yoghurt prepared from milk under treatment C could not be distinguished from other two treatments. In fact, yoghurt under C got a higher total score on organoleptic evaluation than A and B. Low score for body and texture, and falvour was observed under treatment A. This may be attributed to the effect of growth of psychrotrophs in raw milk during refrigeration. From the results, it was concluded that good quality yoghurt can be prepared from milk stored under refrigeration following pasteurization or LP activation. Yoghurt samples prepared from milk stored under treatment A was found to be of inferior quality when compared to B and C. The result also confirmed that LP system can be recommended as a safe preservative for extending storage life of refrigerated milk. When such stored milk was used for yoghurt production, no significant difference in the quality was noticed when compared to yoghurt under treatment B. Suggesting that LP activated milk can be conveniently and economically used for the production of fermented milk products like yoghurt without any apparent harmful effect.ThesisItem Open Access Preparation of mozzarella cheese using skim milk filled with coconut milk(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1994) Gnana Selva, Johnson; KAU; Mukundan, MA detailed study was carried out to determine the quality of coconut fat filled milk for the preparation of Mozzarella cheese and why drinks. Literatures based on filled milk products has been reviewed, apart from the preparation of cheese and why 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, stretchbility and FDM 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 experimental 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 falvoured control, experiment I and II whey drinks were found to be equally acceptable with nodifference on storage studies ar 5 + loC. 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 utilised for preparation of Mozzarella cheese. The quality of such cheese is comparable with that made from cow milk.ThesisItem Open Access Determination of solids content of milk by specific gravity lactometer(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1980) Babu, Mathew; KAU; Subramaniam, MThe methods of estimating total solids content of milk having high percentage by Richmond’s formula (TS = 0.25 L + 1.2 F + 0.14) using Quevenne’s specific gravity lactometer, modified Richmond’s formula (TS = 0.25 L + 1.2 F + 0.50) using Zeal specific gravity lactometer, ISI formula (TS = 0.25 DH + 1.22 F + 0.72) and Ling formula (TS = 0.25 DH + 1.21 F + 0.66) using the density hydrometer, along with the percentage of fat estimated by Gerber method were compared with the value obtained by gravimetric method using 307 samples of milk. In all the milk samples analysed the calculated values of total solids by the formula methods were both higher and lower than the gravimetric values. Since the formulae methods did not give a true estimate of the total solids in milk, modifications to the existing formulae were required by applying a correction factor. It was observed that depending up on the percentage of fat in milk samples, different correction factors were needed to be applied to the different formulae for getting the values close to the gravimetric method. Addition of a correction factor of 0.15 and 0.18 was necessary to the Richmond’s formula for milk samples containing 5.1 to 6.0 and 6.1 to 7.0 per cent fat respectively. For the modified Richmond’s formula, addition of 0.57, 0.53, 0.66 and 0.75 was necessary for samples containing 3.0 to 4.0, 4.1 to 5.0 and 5.1 to 6.0 and 6.1 to 7.0 per cent fat. The addition of a correction factor of 0.16 to the ISI formula was essential for samples containing 4.1 to 5.0 milk fat to get the values in agreement with the gravimetric method. No correction factor was necessary, if Ling formula was used. The order of preference for using various formulae will be (1) Ling formula (2) ISI formula (3) Richmond’s formula (4) modified Richmond’s formula. Ling formula can be used without any correction factor for determination of total solids content of milk for varying percentages of fat from 3..0 to 9.0.ThesisItem Open Access Properties of milk fat of crossbred goats(Department of Dairy Science, College of Veterinary and Animal Sciences,Mannuthy, 1981) Baby George, KAU; Subrahmanyam, MAn investigation was carried out to determine some of the physical and chemical properties of the milk fat of crossbred goats viz. Alpine x Malabari and Saanen x Malabari. A total of 183 milk samples were collected from six each of the two different crossbred goats and out of this 65 samples were used for determination of the size of the milk fat globules. The various fat constants were determined by analyse of ghee prepared by direct heating of cream separated out from the collected milk samples. The average size of the milk fat globule of Alpine x Malabari and Saanen x Malabari was 2.556+ 0.110 and 2.702 + 0.038 microns respectively. The average value obtained for the melting point of Alpine and Saanen crossbred goats’ milk fat was 31.07 + 0.160 C and 31.36 + 0.130 C respectively. The Alpine crossbred goats’ milk fat gave a refractive index of 1.4568 + 0.0001 and an iodine number of 24.95 + 0.28, whereas the corresponding values obtained for the milk fat of Saanen x Malabari goats were 1.4569 + 0.0001 and 25.09 + 0.35. The Reichert-Meisal(RM) number and polensite value obtained for the milk fat or Alpine x Malabari goats were 28.14 + 0.18 and 3.52 + 0.15 respectively. The corresponding values for the Saanen crossbred goats’ milk fat were 28.61 + 0.15 and 3.64 + 0.12 respectively. The Alpine x Malabari and Saanen x Malabari goat milk fat gave an average saponification value of 235.1 + 0.7 and 234.6 + 1.1 respectively. On statistical analysis of the data it has been found that there was no significant difference between the size of the fat soluble and the various other physical and chemical constituents of milk fat of the two groups of crossbred goats. Towards the end of the lactation highly significant increased was noticed in the melting point, refractive index, iodine number, Reichert-Meisal number and polensite value and decrease in the size of the milk fat globule and saponification value of the milk fat of both the Alpine x Malabari and Saanen x Malabari goats.ThesisItem Open Access Use of condensed coconut water in yoghurt(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1996) Malarkannan, S P; KAU; Geevarghese, P IAn attempt was made to incorporate condensed coconut water in partial replacement of MSNF at 25 and 50 per cent level in yoghurt and to study the properties of the product which were compared with normal yoghurt. An exhaustive review of literature on the various physico – chemical properties of yoghurt and other fermented milk products has been presented. The procedure for the analysis of coconut water and condensed coconut water for its chemical composition, mineral profile and method of condensation has been described. The quantity of ingredients for yoghurt preparation was derived by linear programming model. The treatments were divided into TC (control), T2 (25 per cent replacement of MSNF using condensed coconut water without gelatin), T3 (T2 + gelatin at 0.5 per cent level), T4 (50 per cent replacement of MSNF using condensed coconut water without gelatin) and T5 (T4 + 0.5 per cent gelatin). A pre – trial was conducted to find out the ideal combination of starter culture and gelatin to be added to give good quality yoghurt. A combination of four per cent starter culture with 0.5 per cent gelatin produced good quality yohurt and this combination was used in the subsequent trials. A pilot heat stability test was conducted in treatment mixes to find out the amount of trisodium citrate required to provide sufficient heat stability. Yoghurt mixes prepared were analysed for titratable acidity, pH and total solids. Statistical analysis revealed no significant difference between control and treatments for the above. No significant difference was observed in pH and fat between the control and treatments. A significant difference (P < 0.01) in titratable acidity, protein and NPN percentage was observed between control and treatments. The curd tension and viscosity showed a decreasing trend with increasing level of replacement but this properties improved to certain extent by addition of gelatin. The setting time and NPN content showed an increasing trend as replacement level increased and this may be due to high mineral and NPN content in coconut water. There was no significant difference in tyrosine value between the control and treatments T2 and T3. No significant difference was observed in L. bulgaricus count and coliform count between control and treatments, whereas but S. thermophiles and yeast and mould count showed significant difference between control and treatments which may be due to a stimulatory factor in coconut water for yeast and mould and inhibitory factor for S. thermophiles resulting in slow growth. Organoleptic quality revealed that 25 per cent replacement of MSNF with or without addition of gelatin produced comparable scores as that of control yoghurt. A savings of 13.95 per cent and 8.14 per cent in cost can be achieved by 25 per cent replacement of MSNF with or without addition of gelatin respectively. The results of the experiment revealed that 25 per cent replacement of MSNF with condensed coconut water can be successfully tried in preparing yoghurt without affecting the physic – chemical and organoleptic properties together with considerable reduction in cost.
