Survival of Lactobacillus delbrueckii UFV H2b20 in ice cream produced with different fat levels and after submission to stress acid and bile salts

The survival of Lactobacillus delbrueckii UFV H2b20 in three ice cream formulations (low fat, fat free and high fat) was evaluated after the processing and storage at ?16 °C. The survival of L. delbrueckii UFV H2b20 was not significantly affected (P > 0.05) in three ice cream formulations after processing. The same result was observed during storage for 40 days at ?16 °C. Cells of L. delbrueckii UFV H2b20 incorporated in three ice cream formulation survived when exposed to acid stress and bile salts. The results demonstrate that L. delbrueckii UFV H2b20 has potential for being used in ice cream and capacity to resist acid stress and to grow in the presence of bile salts. This demonstrates that reduction of fat in ice cream does not compromise the viability of L. delbrueckii UFV H2B20.     

Effects of Lactobacillus rhamnosus GG addition in ice cream

A 2⁴ full factorial experimental design was applied to verify the effects of Lactobacillus rhamnosus GG (LGG) addition in retail-manufactured ice cream stored at two different freezing temperatures (−16°C and −28°C) and containing two different levels of sugar (15–22%) and fat (5–10%). In addition to microbial counts, the pH, acidity, viscosity of the mixes and functional properties of the ice creams were evaluated. Both fresh and frozen-thawed LGG cells underwent preliminary resistance tests to bile, antibiotics and acidity. The LGG strain proved to be highly resistant to most of the stress factors. When the micro-organism was added to ice cream mixes in a quantity of 10⁸ cfu/g, it did not change the overrun, firmness or melting behaviour of the finished product. Regardless of formulation, no count decay of LGG cells was observed in ice cream stored for up to 1 year.     

Survival of Lactobacillus acidophilus LMGP‐21381 in probiotic ice cream and its influence on sensory acceptability

Probiotic ice cream was produced by incorporating Lactobacillus acidophilus LMGP‐21381 in a standard ice cream mix at initial population above 10⁷ cfu/g. The ice cream mix was inoculated with either freeze‐dried or activated cultures of L. acidophilus and a control treatment without probiotic was also prepared. The product was assessed for the survival of the probiotic strain during the freezing process and during 45 weeks of storage at ?15°C and ?25°C, and also for its sensory characteristics. The results showed that the freezing process caused a significant decrease in the viability of the freeze‐dried culture, but no significant change in the viable counts of L. acidophilus was observed during frozen storage. The sensory attributes of aroma, taste and texture obtained high scores in the sensory evaluation. It was demonstrated that incorporation of either activated or commercial freeze‐dried L. acidophilus culture resulted in a candidate food for the delivery of high levels of this probiotic strain to consumers.     

聚葡萄糖的特性及其在低脂冰淇淋中的应用研究

主要研究聚葡萄糖的特性及其在低脂冰淇淋中的应用。探讨了聚葡萄糖的粘度随温度、浓度、盐类浓度及pH的变化情况,同时也分析了不同添加量对冰淇淋膨胀率的影响,并研究了其对冰淇淋抗融化性能的影响。结果表明,聚葡萄糖的添加将影响冰淇淋膨胀率的提高,同时对冰淇淋的抗融化性能也有一定影响,但添加量高于4%时,抗融化性能变化不大,低脂冰淇淋物性指标低于普通冰淇淋。     

Sensory acceptance and survival of probiotic bacteria in ice cream produced with different overrun levels

The effect of different overrun levels on the sensory acceptance and survival of probiotic bacteria in ice cream was investigated. Vanilla ice creams supplemented with Lactobacillus acidophilus were processed with overruns of 45%, 60%, and 90%. Viable probiotic bacterial counts and sensory acceptance were assessed. All the ice creams presented a minimum count of 6 log CFU/g at the end of 60 d of frozen storage. However, higher overrun levels negatively influenced cell viability, being reported a decrease of 2 log CFU/g for the 90% overrun treatment. In addition, it was not reported an influence about acceptability with respect to appearance, aroma, and taste of the ice creams (P > 0.05). Overall, the results suggest that lower overrun levels should be adopted during the manufacture of ice cream in order to maintain its probiotic status through the shelf life.     

Survival of Lactobacillus acidophilus and Bifidobacterium bifidum in ice cream for use as a probiotic food.

Probiotic ice cream was made by fermenting a standard ice cream mix with Lactobacillus acidophilus and Bifidobacterium bifidum cultures and then freezing the mix in a batch freezer. Survival of the L. acidophilus and B. bifidum, as well as beta-galactosidase activity, was monitored during 17 wk of frozen storage at -29 degrees C. After freezing of the fermented mix, bacterial counts were 1.5 x 10(8) cfu/ml for L. acidophilus and 2.5 x 10(8) cfu/ml for B. bifidum. Seventeen weeks after freezing, these counts had decreased to 4 x 10(6) and 1 x 10(7) cfu/ml, respectively. During the same period, beta-galactosidase activity decreased from 1800 to 1300 units/ml. Probiotic ice cream was prepared at pH 5.0, 5.5, and 6.0 to determine consumer preferences and was compared with standard Utah State University "Aggie" ice cream. All samples were strawberry-flavored and were evaluated by 88 judges. The preferred pH of probiotic ice cream, based on overall acceptance, was pH 5.5. We demonstrated that probiotic ice cream is a suitable vehicle for delivering beneficial microorganisms such as L. acidophilus and B. bifidum to consumers. The bacteria can be grown to high numbers in ice cream mix and remain viable during frozen storage.     

Rheological properties of ice cream mixes and frozen ice creams containing fat and fat replacers

Ice cream mixes and frozen ice creams at milk fat levels of 12%, 8%, 6%, 6% plus a protein-based fat replacer, and 6% plus a carbohydrate-based fat replacer were evaluated for viscoelastic properties by dynamic testing with sinusoidal oscillatory tests at various frequencies. The storage modulus (G'), loss modulus (G"), and tan delta (G"/G') were calculated for all the treatments to determine changes in the viscous and elastic properties of the mixes and frozen ice creams due to fat content. In ice cream mixes, G' and G" exhibited a strong frequency dependence. The G" was higher than G' throughout the frequency range (1 to 8 Hz) examined, without any crossover, except for the 12% mix. Elastic properties of the ice cream mixes decreased as fat content decreased. Tan delta values indicated that fat replacers did not enhance the elastic properties of the ice cream mixes. In all frozen ice creams, G' and G" again showed a frequency dependence throughout the range tested (0.5 to 10 Hz). The amount of fat in ice creams and the degree of fat destabilization affected the elasticity in the frozen product. Even though the ice creams did not have significant elastic properties, when compared as a group the samples with higher fat content had higher elastic properties. The addition of protein-based and carbohydrate-based fat replacers did not enhance the elastic properties of the ice creams but did increase the viscous properties.     

不饱和单甘酯在低脂冰淇淋中的应用

分别将商品饱和单甘酯和另一种富含亚油酸的不饱和单甘酯作乳化剂添加到全脂冰淇淋(脂肪含量为10%)和低脂冰淇淋(脂肪含量为4%)中,共研发出不饱和单甘酯全脂冰淇淋、饱和单甘酯全脂冰淇淋、不饱和单甘酯低脂冰淇淋和饱和单甘酯低脂冰淇淋四个产品。通过对四个产品的冰冷感、硬度、粘度、平滑程度和包口感等进行感官评价,发现脂肪含量及乳化剂的种类对冰淇淋的冰冷感、硬度、粘度、平滑感、包口感等都有影响,全脂冰淇淋比低脂冰淇淋更粘,更滑,更具有包口感,低脂冰淇淋比全脂冰淇淋更硬,冰冷感更强。通过对四种冰淇淋老化料液的膨胀率及冰淇淋成品的抗融性进行了比较,发现不饱和单甘酯能提高低脂冰淇淋的膨胀率,并且不饱和单甘酯冰淇淋比饱和单甘酯冰淇淋具有更好的抗融性。     

Perception of melting and flavor release of ice cream containing different types and contents of fat

Temporal effects of dairy and vegetable fats (0 to 18%) on perception of strawberry flavor release and melting of ice cream were studied using the time intensity sensory method. Also, aroma and flavor attributes of the ice cream samples were evaluated. Only slight effects of fat on the rate of flavor release and flavor intensity were perceived. A slightly faster flavor release from the vegetable fat compared with dairy fat was noticed. Polydextrose and maltodextrin as bodying agents in the fat-free ice cream significantly increased flavor release and melting rate of the ice cream. Increasing fat content slightly retarded melting of ice cream in the mouth. No significant effect of the fat quality on perceived melting was noticed. Significant differences in aroma and flavor attributes of the fat-free and other samples were perceived. Intensity and sharpness of the strawberry aroma and flavor were greater in fat-free samples and they were perceived as nontypical. Fattiness and creaminess were highly correlated. Maltodextrin and polydextrose increased perceived fattiness and creaminess of fat-free ice cream.     

螺旋藻在冰淇淋中的应用研究

螺旋藻添加于冰淇淋中,除赋予产品独特的风味和清新的色泽外,还能显著地提高混合料液的粘度以及冰淇淋的膨胀率和抗融化性能。较适宜的工艺条件为添加量为0.5％;采用85℃,20s的高温短时杀菌;一级均质压力为40MPa,二级均质压力为5MPa;料液老化时间为4h。     

脂肪替代品在冰淇淋中的应用研究进展

脂肪替代品可以替代传统冰淇淋中的脂肪,减少热量,有利于消费者的身体健康。文章综述近年来国内外学者对于脂肪替代品在冰淇淋中的应用研究成果,对其研究方法和结果进行分析、总结,并对脂肪替代品存在的问题和发展前景进行展望。     

Effect of calcium chloride addition on ice cream structure and quality

The influence of calcium fortification by the addition of calcium chloride on quality parameters of ice cream based on physical properties was investigated, as was the effect of κ-carrageenan at modifying the effects of this calcium fortification. Four ice cream mixes of conventional composition, with added κ-carrageenan (0 or 0.025%) and added calcium chloride (0 or 4.4 g L⁻¹ = 40 mM of added Ca²⁺), were prepared. Modulated temperature-differential scanning calorimetry was used to investigate the effect of calcium chloride on the nucleation temperature, enthalpy of melting, and freezing point depression. The protein composition of 15.4% (wt/wt) reconstituted skim milk powder solutions with or without 4.4 g L⁻¹ added CaCl₂ and in the supernatant after ultracentrifugation was determined. Fat particle size distributions in ice cream were characterized by light scattering. Ice crystal sizes before and after temperature cycling were determined by cold-stage light microscopy. The results demonstrated that the addition of calcium chloride led to a substantial increase in ice crystal sizes and in fat partial coalescence, which were exacerbated by the addition of κ-carrageenan. These results can be explained by the interaction between Ca²⁺ ions and casein micelles, rather than any effects on freezing point depression. The calcium ions led to a more compact micelle, less serum β-casein, and high fat destabilization, all of which would be expected to reduce macromolecular structure and volume occupancy in the unfrozen phase, which led to increased rates of ice recrystallization.     

Application of cold- and heat-adapted Lactobacillus acidophilus in the manufacture of ice cream

Manufacture of ice cream using cold- and heat-adapted Lactobacillus acidophilus was studied. Temperature–time combinations at 4 °C for 18 h and at 45 °C for 15 min were set as the adaptation conditions for below and above the optimum growth temperature (37 °C), respectively. Ice cream was produced by two different methods: method 1, ice cream mix was fermented with cold- and heat-adapted L. acidophilus prior to freezing; method 2, cold- and heat-adapted L. acidophilus was added to ice cream mix but the mix was not fermented with L. acidophilus prior to freezing. The lowest reduction ratio was found in the samples produced by using method 1 and cold-adapted L. acidophilus, adapted at 4 °C for 18 h. L. acidophilus survived at the required levels (>10⁶ cfu g⁻¹), with or without an adaptation. The adaptation conditions improved stability of L. acidophilus in the samples, but the magnitude of improvement was small.