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Improving Nutritional Value And Acceptability Of Dairy Products With Lower Contents Of Saturated Fatty

by Muhammad Nadeem | Dr. Muhammad Ayaz | Dr. Imran Javed | Prof. Dr. Muhammad.

Material type: book Book; Format: print Publisher: 2013Dissertation note: Abstract Availability: Items available for loan: UVAS Library [Call number: 1742,T] (1).

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Survival Of Probiotics In Yogurt Ice Cream

by Hafiz Shahzad Muzammil | Dr. Imran Javed | Dr.Muhammad Ayaz | Prof. Dr.

Material type: book Book; Format: print ; Literary form: not fiction Publisher: 2013Dissertation note: This study was designed to produce the yogurt ice cream containing probiotic microorganisms with the recommended levels (106-107) of live cells at the time consumption. The mixture was supplemented before freezing with prebiotics (inulin and oligofructose) and cryoprotectant (glycerol) to see their (prebiotics and glycerol) effects on the survival of Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus acidophilus and Bifidobacterium lactis during freezing process and in storage period. Along with bacterial population, the effects of prebiotics and glycerol supplementation on physicochemical properties like air holding capacity, fat components, protein contents, total solids, hardness, stickiness, melting rate, glass transition, air cell size and ice crystal size were also investigated. Glass transition temperature was analyzed in each treatment mixture before freezing with differential scanning calorimeter. The results from the data obtained at various stages of study have shown different variation pattern for each property. The initial count of each bacterium before freezing in all treatments with in experiment was similar and during the freezing process there was non-significant change in bacterial population. During the storage period at -20°C in the first three weeks there was less loss in all the samples (P<0.05). With the passage of time the death rate is increased in all the samples but this decrease was very less with supplementation as compared to control samples (P<0.05). In the prebiotic yogurt ice cream the greatest loss was observed in L. acidophilus (P<0.05), while the S. thermophilus concentration was the maximum among all the bacteria (P<0.05). At the Summary 110 end of 12 weeks storage period all the bacteria maintained the minimum required (106-107 CFU/g) concentration (P<0.05). The addition of prebiotics and glycerol has increased the total solids of all the samples (P<0.05) that would ultimately led to more overrun percentage. The supplementation of prebiotics and glycerol have shown non-significant effect on the fat quantity while decreased the protein concentration significantly (P<0.05). Fat and protein contents remained unchanged during the storage period of 90 days (P<0.05). The hardness increased with prebiotics and decreased with glycerol supplementation, while the stickiness increased with the increasing prebiotics and glycerol concentration (P<0.05). The melting rate has shown different behavior although the dry matter contents increased with prebiotics and glycerol but it did not support the slow melting (P<0.05). Prebiotics show less effect on glass transition temperature, the increase was very less almost to 1°C. Glycerol has shown most of the effect and it decreased Tg to near about 10°C in 4% supplemented samples (P<0.05). The overrun percentage show most of its effect on probiotics as these bacteria are anaerobic and grow best in absence of oxygen, but the addition of glycerol minimized its effect on survival rate of the bacteria. The overrun have shown no effect on total solids, fat and protein level but it decreased the melting rate at 22 °C. The air act as insulator and prevent the melting of yogurt ice cream (P<0.05). The hardness and stickiness also decreased with increasing level of overrun (P<0.05). The prebiotics and glycerol supplementation have shown non- significant change in air cell size and ice crystal size while overrun percentage has significantly decreased the air cell and ice crystal sizes (P<0.05). Summary 111 In conclusion, the addition of prebiotics and glycerol increased the survival rate by decreasing the freeze damage caused by large ice crystal formation and also improved the physicochemical properties of yogurt ice cream. Availability: Items available for loan: UVAS Library [Call number: 1769,T] (1).

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