The purpose of this research was to incorporate Bifidobacterium angulatum and Bifidobacterium infantis in frozen fermented dairy desserts made from camel or cow milk and to determine their viability during freezing an...The purpose of this research was to incorporate Bifidobacterium angulatum and Bifidobacterium infantis in frozen fermented dairy desserts made from camel or cow milk and to determine their viability during freezing and storage at .20℃. To meet this objective, ice cream mixtures were formulated using camel or cow milk constituents, inoculated with regular yogurt starter （Lactobacillus delbruecldi ssp bulgaricus and streptococcus thermophilus） and incubated at 42℃ till a pH value of 5.0 was attained. The fermented mixes were heated to 80℃ for 5 min in water bath to inhibit yogurt organisms. Bifidobacteria were then added at 2 g/kg mix （1 gram from each Bifidobacterium strain）. The results showed that the initial counts of Bifidobacteria before freezing were 7.3 × 10^8 and 7.1 × 108 cfu/g for camel and cow mix respectively and decreased to 1.06× 10^8 and 1.1×10^8 in the same order （about 0.8 log reduction in the count of Bifidobacteria was observed） after freezing and storage for one day. No significant changes in counts of Bifidobaeteria were found during storage at -20℃ for 17 weeks. Changes in pH and titratable acidity were also studied. No significant changes in titratable acidities of frozen yogurt made from camel or cow milk constituents during storage period were observed.展开更多
T<span>he effects of varying the ratio of ice cream mix to whole milk yogurt on the characteristics of the mixes and the resulting frozen products including their ice cream and frozen yogurt controls were invest...T<span>he effects of varying the ratio of ice cream mix to whole milk yogurt on the characteristics of the mixes and the resulting frozen products including their ice cream and frozen yogurt controls were investigated. Ratios of ice cream mix to yogurt included 100% yogurt for the frozen yogurt control, 25% ice cream mix and 75% yogurt, 50% ice cream mix and 50% yogurt, 75% ice cream mix and 25% yogurt, and 100% ice cream mix for the ice cream control. The resulting mixes were sampled for analysis of total solids content, fat content, pH, and viscosity and then frozen in a batch freezer. The frozen products were analyzed for MRS lactobacilli counts, rate of meltdown at 21°C (volume after 1 h and time for 15 mL to melt), and sensory properties (flavor and body/texture). The total solids contents ranged from 11.89% to 39.65%, and the fat contents ranged from 2.8% to 12.6% for the 100% yogurt and 100% ice cream mixes, respectively. The pH ranged from 4.55 for the 100% yogurt to 6.77 for the 100% ice cream mix. The 100% yogurt sample had the highest viscosity. As expected, the 100% yogurt and the 75% yogurt samples had the highest MRS lactobacilli counts. The rate of meltdown increased with the increasing proportion of ice cream in the yogurt ice cream. The frozen products consisting of 75% and 100% ice cream received the highest flavor scores and body/texture scores. Yogurt ice cream made from 75% ice cream usually had more desirable meltability and sensory properties than yogurt ice creams made from either 25% or 50% ice cream and provides an opportunity for delivering a desirable product that has a healthy imag</span>e.展开更多
文摘The purpose of this research was to incorporate Bifidobacterium angulatum and Bifidobacterium infantis in frozen fermented dairy desserts made from camel or cow milk and to determine their viability during freezing and storage at .20℃. To meet this objective, ice cream mixtures were formulated using camel or cow milk constituents, inoculated with regular yogurt starter （Lactobacillus delbruecldi ssp bulgaricus and streptococcus thermophilus） and incubated at 42℃ till a pH value of 5.0 was attained. The fermented mixes were heated to 80℃ for 5 min in water bath to inhibit yogurt organisms. Bifidobacteria were then added at 2 g/kg mix （1 gram from each Bifidobacterium strain）. The results showed that the initial counts of Bifidobacteria before freezing were 7.3 × 10^8 and 7.1 × 108 cfu/g for camel and cow mix respectively and decreased to 1.06× 10^8 and 1.1×10^8 in the same order （about 0.8 log reduction in the count of Bifidobacteria was observed） after freezing and storage for one day. No significant changes in counts of Bifidobaeteria were found during storage at -20℃ for 17 weeks. Changes in pH and titratable acidity were also studied. No significant changes in titratable acidities of frozen yogurt made from camel or cow milk constituents during storage period were observed.
文摘T<span>he effects of varying the ratio of ice cream mix to whole milk yogurt on the characteristics of the mixes and the resulting frozen products including their ice cream and frozen yogurt controls were investigated. Ratios of ice cream mix to yogurt included 100% yogurt for the frozen yogurt control, 25% ice cream mix and 75% yogurt, 50% ice cream mix and 50% yogurt, 75% ice cream mix and 25% yogurt, and 100% ice cream mix for the ice cream control. The resulting mixes were sampled for analysis of total solids content, fat content, pH, and viscosity and then frozen in a batch freezer. The frozen products were analyzed for MRS lactobacilli counts, rate of meltdown at 21°C (volume after 1 h and time for 15 mL to melt), and sensory properties (flavor and body/texture). The total solids contents ranged from 11.89% to 39.65%, and the fat contents ranged from 2.8% to 12.6% for the 100% yogurt and 100% ice cream mixes, respectively. The pH ranged from 4.55 for the 100% yogurt to 6.77 for the 100% ice cream mix. The 100% yogurt sample had the highest viscosity. As expected, the 100% yogurt and the 75% yogurt samples had the highest MRS lactobacilli counts. The rate of meltdown increased with the increasing proportion of ice cream in the yogurt ice cream. The frozen products consisting of 75% and 100% ice cream received the highest flavor scores and body/texture scores. Yogurt ice cream made from 75% ice cream usually had more desirable meltability and sensory properties than yogurt ice creams made from either 25% or 50% ice cream and provides an opportunity for delivering a desirable product that has a healthy imag</span>e.
