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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 incorporation of condensed cheese whey and bifidobacterium bifidum in yogurt(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1994) Mirza Ismail, Baig; KAU; Prasad, VAn experiment was conducted to assess the possibility of utilization of whey solids in different forrrs in yogurt as a substitute for NDM and also E bifidum as an adjunct with the view to improve the therapeutic value of yogurt A detailed review of literature was presented on the morphological and physiological characteristics of starter cultures importance and utilization of whey solids effect of long term storage on starter bacteria and other related aspects Methodology of condensation of cottage cheese whey preparation of whey protein dispersion and manufacture of set and frozen yogurt has been described Important analytical procedures were presented The experiment comprised of part A and part B based on the starter culture The mix under the part A were fermented with conventional yogurt starter culture viz S5 salivanus subsp thermophilus and L delbrueckn subsp bulgaricus as against this the mix under part B were fermented with conbination of conventional yogurt starter and B bifidum Fa h part comprised of four treatments based on types of mill solids used to raise the content of SNF to 13 per For A-II and B II condensed whey was used to replace 50 percent NDM Mixes under A III and B III were fortified with condensed whey to replace 100 per cent NDM and whey protein dispersion was used to replace complete NDM under A-IV and B-IV The results obtained had been compared with similar reported studies and conclusions were drawn The data regarding the starter bacterial count indicated the optimum growth of thermophilus bulgaricus and bifidobacteria in yogurt fortified with different forms of vihey solids The count of thermophilus and bifidobacteria were higher with the fortification of whey solids m yogurt mix and the growth of bulgancus was not adversely affected in the presence of the whey solids Incorporation of B bifidum stimulated the growth of thermophilus however it was found to have some inhibitory effect on bulgaricus count The inhibitory effect of B bifidum on bulgaricus was lesser in presence of whey solids than in yogurt fortified with NDM Optimum growth of B bifidum was obtained when grown in association with conventional yogurt culture cent For mixes under A-I and B-I fortification was withThesisItem 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 Preparation of hard ripened cheese from goats` milk(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1985) Anil Kumar, A G; KAU; Subrahmanyam, Metc. An investigation was undertaken to produce a hard ripened variety of cheese from goats’ milk and to compare it with that produced from cow’s milk. Pooled samples of raw milk collected from the goats of the All India Co-ordinated Research Project on Goats for Milk, Mannuthy and the Cows of the University Livestock Farm, Mannuthy were heat treated (72.60 C/15 seconds) and used to prepare six batches of cheese. Samples of cheese collected prior to and after ripening were subjected to various analyses. The results of the study indicated that the yield of cheese from goats’ milk (1.430 kg from 10.0 litres milk) was higher than that obtained from cows’ milk (1.145 kg from 10.0 litres milk). The moisture content of cheese was found to decrease during ripening. Goats milk cheese had a lower moisture content prior to and after ripening at 50 C, but after ripening at 100 C cows’ milk cheese showed a lower value. The cheese from cows’ milk had a higher level of fat as compared to that from goats’ milk. The fat content of cheese was found to increase during the ripening process. The total protein content was higher in goats’ milk cheese both prior to and after ripening, but the level of soluble protein was found to be higher in cows’ milk cheese. Ripening at 100 C produced a higher level of soluble protein as compared to ripening at 50 C. Although ripened cheese contained a higher salt content as compared to green cheese, significant difference could not be observed in its level between goats’ and cows’ milk cheese. The level of steam volatile free fatty acids (SVFFA) was slightly higher in cows’ milk cheese prior to ripening, but after ripening goats’ milk cheese showed higher values. Ripening at 100 C produced a higher level of SVFFA as compared to 50 C. The pH of cheese made from goats’ milk was slightly lower than that made from cows’ milk, prior to and after ripening. The pH was also found to increase during ripening, the change being more marked at 100C. Goats’ and cows’ milk cheese ripened at both the temperatures (50 C and 100 C) showed no coliforms, but the green cheese from goats’ milk showed higher coliform load. The cows’ milk cheese was judged better than goats’ milk cheese. Although not significant, samples of cheese ripened at 100 C scored higher than those ripened at 50 C, the difference being more remarkable in cows’ milk cheese. Samples of cheese produced in the present study was found to conform to the standards prescribed for hard cheese under the PFA Act (1982).ThesisItem Open Access Technological evaluation of Kera ice cream(Department of Dairy Science, College of Veterinary and Animal Sciences, Mannuthy, 1996) Geevarghese, P I; KAU; Francis, U TAn experiment was conducted to assess the suitability of incorporating coconut fat in the form of coconut cream in preparing ice cream and ice cream mix powder replacing milk fat at 25, 50, 75 and 100 per cent levels (treatments) so as to reduce the cost of preparation of ice cream. The product developed was named as kera ice cream and the qualities were compared with normal ice cream (control). Kera ice cream was prepared with pineapple flavour and a combination of sodium alginate and glyceryl monosterate as stabilizer since it was found to be the most suitable. It was found that replacement of milk fat with coconut fat at any level does not influence the acidity, pH and specific gravity of kera ice cream mix. The relative viscosity of kera ice cream was increased as fat substitution level increased. Higher surface tension was observed for the control, and among treatments it showed a gradual increase as replacement level increased. It was observed that the overrun percentage increased as replacement with coconut fat increased. Contrary to this a decreasing trend in meltdown time was observed as percentage replacement with coconut fat increased. Whipping ability was lowest for the control during the first 5 min of freezing but it significantly increased during the second five min of freezing. Structural details of the ice cream revealed that as replacement level increased the air cell diameter and cell wall thickness increased. Organoleptic quality of kera ice cream were comparable to normal ice cream. The savings in cost of production for kera ice cream with 100 per cent replacement was calculated as 40.57 per cent compared to control. The properties of the reconstituted ice cream revealed more or less similar trend in characters like acidity, pH, specific gravity, overrun, meltdown time and organoleptic properties as that of the freshly prepared ice cream. The ultra structure of the kera ice cream mix powder particle were studied and it revealed that as replacement level increased the particle size also increased. Clumping of the particles and irregular surface were more evident at 75 and 100 per cent level whereas particles of the control and 25 per cent had smooth surface. Solubility index of the powder increased as percentage replacement increased. Significant difference could be noted with regard to bulk density and percent volume occupied by the powder particle. Storage studies were conducted with different packaging material and metallised polyester polyethylene was found to be the best. The moisture and titratable acidity of kera ice cream mix powder with and without antioxidant were significantly higher at any replacement level at 180 days of storage. The thiobarbituric acid value showed a significant difference for the powder without antioxidant at 120 days of storage and with antioxidant the difference could be noted at 180 days of storage. Peroxide value was recorded as zero at different periods of storage upto 180 days of storage. At 180 days of storage, powder without BHA at any replacement level showed significant difference whereas in antioxidant added powder difference could be noted at 75 and 100 per cent replacement levels. Nutritional qualities of kera ice cream was evaluated by rat feeding trials and was found that protein efficiency value and feed efficiency were comparable to ice cream diet. The cholesterol and triglyceride level in animals fed with kera ice cream and ice cream were also not different. Pathological examination of carcases and tissues of animals under treatment and control groups did not reveal significant changes indicating that incorporation of coconut fat cannot cause any untoward effect in organs and tissues of animals. It can be concluded that coconut fat can be incorporated in the prepartation of ice cream and mix powder with out any noticeable changes in the quality. Addition of antioxidant prolongs the keeping quality of the powder by two months. There is no health hazard in consuming the kera ice cream as revealed by the pathological examination of tissues from the experimental animals fed with kera ice cream.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