The effects of supplementation of oligofructose or inulin on the rheological characteristics and survival of Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 in low-fat ice cream stored at -18 degrees C for 90 d were studied. Addition of oligofructose or inulin to ice cream mix significantly increased apparent viscosity and overrun and developed the melting properties in ice cream during storage (P < 0.05). However, the highest increase in firmness, the lowest change in melting properties, and the longest 1st dripping time were obtained in probiotic ice cream containing inulin (P < 0.05). Some textural properties have also improved especially by the end of storage. Freezing process caused a significant decrease in the viability of Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 (P < 0.05). Oligofructose significantly improved the viability of L. acidophilus La-5 and B. animalis Bb-12 in ice cream mix (P < 0.05). Although the viable numbers for both bacteria decreased throughout the storage, the minimum level of 10(6) CFU/g was maintained for B. animalis Bb-12 in only ice cream with oligofructose during storage.

The influence of milk protein-based ingredients on the textural characteristics, sensory properties, and microstructure of probiotic yogurt during a refrigerated storage period of 28 d was studied. Milk was fortified with 2% (wt/vol) skim milk powder as control, 2% (wt/vol) sodium calcium caseinate (SCaCN), 2% (wt/vol) whey protein concentrate (WPC) or a blend of 1% (wt/vol) SCaCN and 1% (wt/vol) WPC. A commercial yogurt starter culture and Bifidobacterium lactis Bb12 as probiotic bacteria were used for the production. The fortification with SCaCN improved the firmness and adhesiveness. Higher values of viscosity were also obtained in probiotic yogurts with SCaCN during storage. However, WPC enhanced water-holding capacity more than the caseinate. Addition of SCaCN resulted in a coarse, smooth, and more compact protein network; however, WPC gave finer and bunched structures in the scanning electron microscopy micrographs. The use of SCaCN decreased texture scores in probiotic yogurt; probably due to the lower water-holding capacity and higher syneresis values in the caseinate-added yogurt sample. Therefore, the textural characteristics of probiotic yogurts improved depending on the ingredient variety.

No abstract

Nine organic acids (formic, pyruvic, lactic, acetic, orotic, citric, uric, propionic, and butyric) were analyzed during ripening of pickled White cheese for 12 mo by high-performance liquid chromatography with a reverse phase C18 (120x 5-mm) column and UV detector. The level oftotal organic acids showed an increase along the ripening period, but its composition varied during the process. Initially, lactic acid accounted for 95% of the total, after 9 and 12 mo of ripening, butyric acid constituted 20 and 27% of the total, respectively. Each organic acid presented a characteristic pattern of change during ripening. Discriminant analysis classified cheeses according to their age. Stepwise regression analysis allowed estimation of the ripening time of samples according to their organic acid levels.

The viability of yoghurt bacteria and two commercial strains of bifidobacteria was assessed in either yoghurt containing chicory fructooligosaccharide (FOS) or without any prebiotic, during 28 days storage at 4°C. All the products showed a decrease in the viable count of yoghurt bacteria and bifidobacteria during storage. Numbers of Lactobacillus delbrueckii ssp. bulgaricus decreased faster than those for Streptococcus thermophilus. The viability of bifidobacteria in yoghurt was affected by the strain type and the presence of FOS. Bifidobacterium animalis exhibited better stability in the yoghurt than B. longum. The recommended level of 1 million cells was exceeded for B. animalis throughout storage. The highest viable number of bifidobacteria (3.59-2.25 · 10 7 CFU g )1 ) was obtained in the product containing B. animalis and FOS. Viability of B. longum in yoghurt containing FOS remained above 10 6 CFU g )1 for up to 21 days, whereas this level was maintained for only 7 days for that organism in yoghurt without any prebiotic.