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ThesisItem Open Access Lactobacillus acidophilus as a dietary adjunct in Dahi and Yogurt(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1995) Appalo Eleven, S; KAU; 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 alongw ith normal yogurt cultures. This wascompared with control yogurt prepared using normal yogurt cultures. The samples were then analysed for various parameters. There was an increase in the p-galactosidase specific activity of treatment dahi when compared to the control dahi. But m the case of yogurt, the treatment yogurt was having a low 3-galactosidase specific activity when compared to the control yogurt. Control dahi showed inhibition against E. aerogenous, M. falvous, E. coli and S. aureus. It did not showed any inhibition against B. cereus. Treatment dahi exerted a significantly high inhibition zone against all the test organisms m comparison to control dahi. Control yogurt inhibited only E. aeroqenous and E. 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. delbruecii ssp bulgancus showed a poor growth, whereas S. salivanus 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, LDL- Cholesterol and cardiac risk factor of the treatment groups were significantly lower than the respective controls. The HDL-Cholesterol was high m 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.ThesisItem Open Access Effect of feeding additives on total solids of cow's milk(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1992) Sathian, C T; KAU; Francis, U TA study was undertaken to evaluate effect of feeding acetic acid (200 ml/day), sodium bicarbonate (1.5% of the concentrate), potassium carbonate (1.2% of the concentrate) and magnesium oxide (0.8% of the concentrate) on solids content of cow's milk. An exhaustive review of literature has been presented about the use of these additives in cow ration for modifying milk composition. Six cross-bred.cows within the stage of 60 to 160 days of lactation with milk fat content of three to four per cent were alloted for feeding each additive. The feeding was done for 25 days of which first 20 days served as adaptation period. Milk samples were collected during pre-treatment period/ adaptation period, treatment (experimental) period and post-feeding period. Pre treatment period samples served as the control. Milk samples were analysed for fat per cent, protein per cent and total solids per cent. The methods of analysis have been detailed. Solids-not-fat per cent was found out by difference. Daily milk yield (kg/d) of each cow was noted. Fat yield (kg/d) and protein yield (kg/d) were calculated. The feed consumption by animals was recorded. The effect of additives were compared. Sodium bicarbonate and potassium carbonate significantly increased fat per cent of milk by 0.4 and 0.35 from pre-treatment values respectively. Acetic acid and magnesium oxide produced only non-significant increases in fat per cent which continued during post-feeding period also. Potassium carbonate feeding increased milk protein per cent significantly by 0-42 from pre-treatment value. Comparison between additives showed that effects produced by potassium carbonate on protein per cent significantly differed from effects produced by acetic acid. Total solids content was significantly increased by 0.42 per cent on feeding potassium carbonate from pre treatment value. None of the additives produced significant changes in solids-not-fat percentage. Sodium bicarbonate and potassium carbonate significantly reduced milk yiled by 1.28 kg/d and 0.71 kg/d from the pre-treatment values respectively. This reduction continued during post-feeding period. Non-significant changes in fat yield and protein yield were produced by all the additives except potassium carbonate. Feed consumption by the animals was not affected by feeding any of the additives Sodium bicarbonate and potassium carbonate significantly increased milk fat per cent. But their use in the ration is not recommended due to significant reduction in milk yield.ThesisItem Open Access Effect of nisin on the keeping quality of dahi(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1992) Sreeja Ramachandran; KAU; Prasad, VAn experiment was conducted to find out the effect of preservatives such as nism 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 m dahi, keeping quality and other related aspects. The methods of analysis of s8rae 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 IU n i s m / i W g curd (2) Treatment B - with 10 ml of nisin producing organism capable of producing 1000 IU of nism/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 and 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.ThesisItem Open Access Utilisation of skim milk filled with coconut milk for preparation of indigenous dairy products(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1992) Mini Jose; KAU; Mukundan, MA detailed study was carried out to determine the quality of coconut fat filled milk for the preparation of indigenous milk products such as paneer, rasogolla and whey drinks. A modified version of Precision Penetrometer to measure the springiness of rasegolla was designed, fabricated and used in the present study. An exhaustive review of literature has been presented on the use of vegetable fat for substitution of milk fat for preparation of various dairy products apart from preparation and other related aspects of paneer, rasogolla and whey drinks. The methods of chemical analysis and sensory evaluation of these products have been detailed. The control samples of paneer, rasogolla and whey drinks were prepared using cows' milk while experimental samples were prepared using skim milk filled with coconut fat. The milks were standardized to four per cent fat. The moisture, fat and acidity were found to be similar in control paneer and experimental paneer. The control paneer was found to have higher yield but low protein content when compared to experimental paneer. On sensory evaluation, control pander was graded as of 'excellent quality* while experimental paneer was graded as of 'good quality'. The control and experimental samples of rasogolla were found to have same springiness. Control samples of rasogolla obtained 'excellent' grade on sensory evaluation but the experimental rasogolla was graded as of 'good' quality. The difference in the quality of paneer and rasogolla was due to the natural flavour of coconut milk Icarried over to the products. Both control and experimental samples of rasogolla were found to have good shelf life of three days, at room temperature. Pineapple and lemon flavoured control and experimental whe.y drinks were found to be equally acceptable with no difference in appearance, odour, flavour and body characteristics. The chemical and sensory evaluation of paneer, rasogolla and whey drinks prepared from cows' milk and coconut fat filled milk revealed no significant difference between them.ThesisItem Open Access Immobilization of Beta Galactosidase for production of fermented milk products with low lactose(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1996) Geetha, R; KAU; Prasad, VAn immobilized β – galactosidase enzyme system was developed using permeabilized cells of K. fragilis as an enzyme source and food grade agar as the immobilizing agent. This was utilised for hydrolysing lactose content present in milk, which in turn was used for preparing selected fermented products with low lactose content. An attempt was also made to assess the possibility of utilisation of whey as a medium for culture maintenance with a view to utilise the by – product. A detailed review of literature has been presented about β – galactosidase specific activity of different organisms, various immobilization techniques,influence of lactose hydrolysis on physico chemical properties of the product and also about the utilisation of whey as a media for culture maintenance. The experiment comprised of determination of β – galactosidase specific activity of permeabilized cells of three selected organisms and assessing the suitability of agar and sodium alginate as immobilizing agents. Since β – galactosidase specific activity was found to be the highest for K. fragilis, it was selected as the best enzyme source. Agar was selected as the suitable immobilizing agent because it was found to be safe, economical and comparatively more efficient. Using these two raw materials an efficient immobilized enzyme system was developed and its efficiency was assessed by estimating the rate of lactose hydrolysis at fixed time intervals. Selected strains of starter bacteria were screened for their performance in four different media viz. Skim milk, 50 per cent lactose hydrolysed skim milk, condensed whey, and 50 per cent lactose hydrolysed condensed whey. Two media were selected from among the four, which stimulated the starter activity and used for further studies. Three different products viz., yogurt, bifidus yogurt and acidophilus milk were prepared using 50 per cent lactose hydrolysed milk obtained by passing through the immobilized enzyme system and cultures maintained separately in lactose hydrolysed milk and lactose hydrolysed whey. Two control products were prepared with ordinary milk and above described cultures. All the three products under different treatments were analysed for acidity, pH, tyrosine value, total lactic count and sensory evaluation. The results obtained in the study were compared with similar reported findings and the following conclusions were made. 1. Permeabilized cells of K. fraglis possessed better B – galactosidase specific activity than the cells of S. thermophiles and L. delbrueckii sub sp. bulgaricus. 2. Food grade agar was found to be an efficient immobilizing agent than sodium alginate. 3. The immobilized enzyme prepared with 10 g of K. fragilis could hydrolyse 50 per cent of lactose content present in 250 ml of milk, after holding in the column for four hours at room temperature (300 C). 4. The rate of lactose hydrolysis was found to be the maximum within first half an hour, thereafter a decline in the rate of hydrolysis was observed. 5. This system was repeatedly used in five batches without any change in its efficiency or mechanical stability of the beads but after which a reduction in activity was noticed. 6. A slight brownish discolouration was observed on the beads when the column was stored for a long period. 7. Repalcement of skim milk with whey was a starter media slightly enhanced the activity of cultures, especially, S. thermophilus, L. lactis and B. bifidum whereas L. acidophilus and L. delbrueckii sub sp. bulgaricus performed better in skim milk, especially when the media was subjected to lactose hydrolysis. 8. The utilisation of lactose hydrolysed milk for preparation of products slightly enhanced the acidity, proteolytic activity and viable cell count of yogurt, bifidus yogurt and acidophilus milk. 9. In the case of treatment yogurts (Y1 and Y2) prepared with lactose hydrolysed milk, a significantly higher protolytic activity was observed. 10. Organoleptic evaluation indicated that the utilisation of lactose hydrolysed milk and cultures maintained in lactose hydrolysed skim milk and whey did not affect the flavour and textural characteristics of yogurt. On the contrary the flavour as well as body and texture scores of bifidus yogurt and acidophilus milk were slightly improved by this technique.ThesisItem Open Access Utilization of goat milk for preparation of mozzarella cheese(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1995) Phola Konyak, W; KAU; Mukundan, MA study was carried out to assess the suitability of goat milk for the manufacture of Mozzarella cheese and to compare with that of cow milk. Cow and goat milks were subjected to chemical analysis prior to manufacture of cheese. The milks used were standardized to 4 per cent fat. Cow milk, goat milk and combination of cow and goat milk 1:1 ratio were pasteurised at 720C for 16 seconds and control, experimental I and II Mozzarella cheese samples were prepared respectively. A total of 6 replications were carried out. The prepared cheese samples were subjected to chemical analysis. The yield, moisture content, fat, protein and total solids content were statistically analysed. Analysis of variance showed significant difference (P < 0.01) between the samples. The stretchability and organoleptic quality of experimental I Mozzarella cheese prepared from goat milk was lower, but experimental II Mozzarella cheese prepared from the mixture of cow and goat milk was comparable to control prepared from cow milk. Mozzarella cheese whey was utilized for preparation of carbonated and non carbonated whey drinks using pineapple and lemon flavours. Carbonated whey drinks stored at room temperature (290 C) and non carbonated stored at 5 + 10 C for 3 days were of good quality. Total bacterial counts of whey drinks during storage at 24 hours intervals were recorded. The present study revealed that mozzararella cheese prepared from combination of cow and goat milk is 1:1 ratio was comparable to control Mozzarella cheese prepared from cow milk. Goat milk Mozzarella cheese eventhough comes within the acceptable level was of low quality as compared to control samples. However, goat milk can be utilized for manufacture of Mozzarella cheese