Effects Of Storage And Processing Condition On The Quality Of Whola Milk Powder
Material type: Book ; Format:
Publisher: 2009 Dissertation note: Milk is a complex mixture of fat, proteins, carbohydrates, minerals, vitamins and other miscellaneous constituents dispersed in water. Milk production in flush season is much more than the requirement. Milk production and supply fluctuate through out the year and during winter it is surplus to its demand. Dairy is one of the expanding industrial sectors in Pakistan; about 17 units are engaged in the production of various dairy products. Surplus milk is available in winter and this is the normal practice of dairy industry in Pakistan that surplus milk is converted in to different types of milk powders. The objectives of the study were to evaluate the physico- chemical and keeping quality of whole milk powder commercially available in the market and comparative study of functional properties among different brands of whole milk powders, evaluate the storage stability of different brands of whole milk powder atl5°C, 25°C and 40°C temperature and study the effects of processing conditions indicator like Hydroxymethyl Furfural (HMF) during storage.
Project was undertaken to study the effect of storage temperatures (15, 25 and 40°C) and processing conditions on physico chemical and sensory characteristics of whole milk powder. Statistical analysis of whole milk powder samples indicated during storage non significant changes in protein, ash, fat, lactose, acidity, burnt particles within the treatments as a function of storage was observed. Significant changes were recorded in free fatty acids, solubility index and per oxide value within the treatments and during storage period of 120 days. At 120 days of storage minimum increase in free fatty acids and peroxide value was noted in T3. Acidity, free fatty acids and peroxide value increased throughout the storage period of 120 days but at 15 °C the effect of storage on free fatty acids and peroxide value was comparatively less than 25 and 40 °C.
Hydroxy methyl furfural was found significant within the treatments and effect of storage period and temperature was also significant. Hydroxy methyl furfural almost remained same at 15 °C, with the increase of temperature it increased significantly. Sensory evaluation was carried out by a panel of six trained judges it was noted that score for color, taste; smell and mouth feel decreased with the increase of temperature and storage period. The highest score for color, smell, taste and mouth feel was obtained by T3 during 120 days of storage. Chemical analysis of whole milk powder samples showed that whole milk powder samples stored at 40 °C were most affected in terms of physico chmeical and sensory quality.
Overall results indicated that physico chemical quality and sensory properties of T3 was found best and it was comparatively less affected by storage temperatures. On the basis of this study it is recommended that for proper storage of whole milk powder 15 °C temperatures is suitable.
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Effect Of Various Levels Of Probiotics(Lactobacillus Acidophilus And Bifidobacterium Bifidum) On Physicochemical, Microbiological And Sensory Characteristics Of Ice Cream
Material type: Book ; Format:
Publisher: 2010 Dissertation note: Ice-cream is a frozen mixture of combination of components, such as milk, sweeteners, stabilizers, emulsifiers and flavoring agents. Ice-creams are food products which show excellent potential for delivering probiotics to consumer. Probiotics are basically health promoting gut friendly bacteria. Minimum viable quantity of probiotics which is beneficial for human beings is 106 or 107 cfu/g. Benefits are strain specific and cannot be extrapolated. Keeping in view the importance of probiotics the present research study was planned to determine the influence of various levels of probiotics (Lactobacillus acidophilus and Bifidobacterium bifidum) on physicochemical and sensory characteristics of ice cream, assessing the viability of probiotics at different storage periods and to give innovative and value added product to commercial ice cream manufacturers. In order to carry out the study, Freeze dried cultures of two probiotic bacteria i.e., Lactobacilus acidophilus (DVS LA-5 Probio-Tec®) and Bifidobacterium bifidum (DVS BB-12® Probio-Tec®) were obtained from Chr. Hansen (Hørsholm Denmark). The probiotic cultures were stored at - 18? C in freezer.
These two probiotic strains were inoculated alone and in combination in ice cream mix at three different inclusion levels. Hence there were total nine experimental treatments. A regular or control ice cream i.e., without any probiotic culture was also used along with treatments. Probiotic ice cream preparation and physical tests were performed at walls Ice Cream factory, Lahore, Pakistan. Chemical analysis were performed at department of Food and Nutrition laboratory, whereas, Microbiological tests were conducted at department of Microbiology, University of Veterinary and Animal Sciences, Lahore.
Probiotic ice cream was manufactured in the pilot plant of the research and development department, Unilever Walls Ice Cream factory Lahore. Ice cream mix was prepared by following standard procedure. After mixing, homogenization and pasteurization of ice cream mix, it was cooled to 41°C and was divided into ten equal parts. Probiotics cultures alone and in combination, according to experimental design, were added in ice cream mix. Then it was fermented for two hours at 41°C. Then mix was aged at 4°C for a period of 2 hours followed by freezing and hardening. Ice cream samples were packed in one liter plastic tubs and were stored at - 18°C in freezer.
Ice cream samples were analyzed after every fifteen days interval during storage period of three months. Physicochemical tests including overrun, viscosity, melting resistance, pH, acidity, fat, protein, total solids were performed by following the methods of AOAC (2000). As far as results of physicochemical tests are concerned, it was observed that both Lactobacillus acidophilus and Bifidobacterium bifidum are able to produce acid in ice cream. Acidity tended to increase as a result of increase in the number of bacteria. Highest pH was observed in control (R) sample, whereas, lowest pH was observed for samples having mixed culture. pH tended to decrease throughout storage. Lactobacillus acidophilus found more acid producing than Bifidobacterium bifidum. Ice cream samples containing high levels of probiotic bacteria showed decreased value of overrun. Whereas no effect was found in case of viscosity. Samples with increased level of bacteria showed significantly less melting resistance. Also, melting resistance tended to decrease significantly with increase in storage. Total solids and fat contents remained constant throughout storage and effect of treatments was statistically non significant. In case of protein contents, a positive correlation was observed .Increase in level of bacteria , increased the protein contents of ice cream, but it remained constant throughout the storage.
Viable probiotic bacteria were enumerated by using the technique of spread plate method by using RCA media. In present study, cell count of viable bacteria, after fermentation, showed increase number of colonies. Samples inoculated with B3 were excellent in regard of exhibiting probiotic property followed by treatments B2 and A3. Treatments in combination i.e., C1, C2 and C3 showed results close to treatments having single cultur , which might be due to nutrients competency with each other. Furthermore, it was quite difficult to count colonies in mixed culture. Ice cream samples prepared from mixed culture were more acidic in taste and flavour and were least liked by sensory evaluators.
Probiotic ice cream was subjected for sensory evaluation by five panel of judges. They rated ice cream by using nine point hedonic scale. Color of ice cream did not show any change throughout storage and was not affected by various levels of probiotics. No surface spots were found in any treatment at any storage period. Due to acid producing nature of probiotics, slight acidic changes were observed in thickness, flavour and taste of ice cream. However, overall acceptability for all probiotic ice cream was good. The data were analyzed according to analysis of variance technique under factorial arrangement. Significance of means was compared by using Duncan's multiple range test.
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Qualitative Studies Of Cheese Made By Using Bifidobacterium Bifidum & Lactobacillus Acidophilus
Material type: Book ; Format:
; Literary form:
Publisher: 2014 Dissertation note: Abstract
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Development And Quality Enhancement Of Cottage Cheese Made From Nili Ravi Buffalo Postpartum Milk (Colostrum)
Material type: Book ; Literary form:
Publisher: 2016 Dissertation note: Colostrum is milk obtained from mammals secreted after parturition. It differs from normal milk
as it contains numerous bioactive components which include growth factors, lacto-peroxidase,
lacto-ferrin, Igs, lysozyme, nucleosides, vitamins, oligosaccharides and peptides, which are health
promoters. Cottage cheese is an excellent source of cyanocobalamin, riboflavin and pyridoxine.
Using colostrum for making cottage cheese can give opportunities to increase cottage cheese
quality which may be more functional, healthier with high yield. Preservation of colostrum in the
form of cottage cheese can be supportive for obtaining functional cheese with enhanced shelf life.
Nili Ravi Buffalo postpartum milk was used for the production of Cottage cheese. While the
control was prepared from Nili-Ravi buffalo normal milk. Milk was pasteurized at 63 °C for
around 30 minutes in batch pasteurizer. Then the milk temperature was brought down at 37°C for
inoculation with the mother cultures mentioned above at 2% level. Three replicates for each
treatment was prepared. Incubation continued for 30 minutes at 42°C. Then 1.7 ml CaCl2 was
added and after 10 minutes 1.7 ml of rennet solution was added in cheese milk and left for another
40 minutes for coagulation. Then the curds was cut into 1cm3 and healed for 10 minutes. The
temperature is raised to 55°C for cooking for 30 minutes. Then whey was drained for 24 hrs. The
curd was pressed and shaped into mold and then wrapped in aluminum foil and stored at 4°C for
7 days for further analysis. The physicochemical analysis such as pH, Acidity%, Fat %, TS %, Ash
%, Chlorides %, Casein %, Protein% and Lactose% of Colostrum and Colostrum based Cottage
cheese with respect to control was carried out by standard methods as described in AOAC. The
data thus collected were analyzed through one way analysis of variance under Completely
Randomized Design (CRD). Means were compared through Duncan’s Multiple Range (DMR)
Test (SAS 9.1 Statistical Software).
Physicochemical analysis of Colostrum showed that pH is in the increasing trend with the increase
of age of milk and results showed that Colostrum pH values lower than milk values and were
related to the high proteins content that is usually revealed in colostrum obtained 2-3 days after
birth. While the trend of titratable acidity %, fat %, chlorides %, specific gravity, ash %, Total
solids %, Total protein % and casein % is decreasing with an increase in the age (Days) of
Physicochemical analysis of Colostrum Cottage Cheese showed that the trend of pH of colostrum
cottage cheese remained constant with the increase of age. The trend of lactose% and ash % is
increasing with an increase in the age of postpartum milk. While the trend of titratable acidity %,
fat %, chloride%, total solids %, total protein % and casein % of cottage cheese is decreasing with
an increase in the age (days) of postpartum milk.
Microbiological analysis of Cottage cheese was examined. Coliforms remained absent (<10 cfu/g)
during whole storage time. Total Plate Count (TPC) was not significantly different throughout the
storage period as it renders growth if there are hygiene and proper storage conditions available.
Sensory evaluation was be carried out using criteria of appearance, taste, color, flavor and whole
acceptability on a hedonic scale of nine points. T0, T3, T4 and T5 showed cheese like aroma, T1
showed yoghurt like aroma while T2 showed cheese like/ slight acidic aroma after 7 days of storage
period. T0 and T5 showed whitish appearance, T1 showed light yellow appearance, T2 showed
slight creamy like color after 7 days of storage period while T3 and T4 showed off white
appearance after 7 days of storage period. T0, T4 and T5 showed light acidic flavor, T1 and T2
showed slight saltish / most bitterness in taste while T3 showed acidic taste after 7 days of storage
period. T0 and T5showed granular texture with no creaminess, T1 showed soft yoghurt like
texture, T2 showed meaty / hard texture while T3 and T4 showed harder toffee like texture after 7
days of storage period.
Colostrum is the most proteinaceous food as compared to milk and improves the nutritional aspects
as well as quality and yield of the products. So Cottage cheese made from Colostrum is more
nutritious, functional with probiotic characters as well as enhanced physico-chemical properties
with high yield.
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