Viability of yogurt starter cultures and Bifidobacterium animalis was assessed during 28 d storage in reduced-fat yogurts containing 1.5% milk fat supplemented with 1.5% fructooligosaccharide or whey ...protein concentrate. These properties were examined in comparison with control yogurts containing 1.5% and 3% milk fat and no supplement. Although fructooligosaccharide improved the viability of Streptococcus thermophilus, Lactobacillus delbrueckii subs. bulgaricus, and Bifidobacterium animalis, the highest growth was obtained when milk was supplemented with whey protein concentrate in reduced-fat yogurt (P < 0.05). Supplementation with 1.5% whey protein concentrate in reduced-fat yogurt increased the viable counts of S. thermophilus, L. delbrueckii subs. bulgaricus, and B. animalis by 1 log cycle in the 1st week of storage when compared to control sample. Similar improvement in the growth of both yogurt bacteria and B. animalis was also obtained in the full-fat yogurt containing 3% milk fat and no supplement. Addition of whey protein concentrate also resulted in the highest content of lactic and acetic acids (P < 0.05). A gradual increase was obtained in organic acid contents during the storage.
A gas chromatographic procedure was used for the analysis of conjugated linoleic acid (CLA) isomers, c9t11-CLA and t10c12-CLA, in yoghurts containing
Lactobacillus acidophilus or
Bifidobacterium ...animalis and/or 2% fructooligosaccharide (FOS). Two groups of set yoghurts containing no supplement or 2% FOS were manufactured using three different starter cultures to determine the effect of processing, starter culture type, FOS supplementation and storage on CLA content. Processing of milk into yoghurt, the addition of FOS alone and storage for 28
d did not significantly affect CLA isomer formation in yoghurts
(
P
>
0.05
)
. However, significant increases in both isomer formation were obtained by using
L. acidophilus or
B. animalis in yoghurt manufacture
(
P
<
0.05
)
. The highest increases in c9t11-CLA isomer and total CLA content were found in yoghurts manufactured with
L. acidophilus and FOS (2.71-fold increase in total CLA), and
B. animalis and FOS (2.90-fold increase in total CLA)
(
P
<
0.05
)
.
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 (120× 5-mm) column and UV detector. The level of total 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 effects of yogurt and acidophilus yogurt on the weight gain, serum cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, triglycerides, and the numbers of fecal ...lactobacilli and coliforms were investigated in mice assigned to three dietary treatments for 56 d: 1) commercial rodent chow and water (control), 2) commercial rodent chow and yogurt made from milk inoculated with a 3% (vol/vol) liquid culture of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus (yogurt), and 3) commercial rodent chow plus yogurt made from milk inoculated with a 0.01% (wt/vol) freeze-dried culture of Streptococcus thermophilus plus Lactobacillus acidophilus. The weight gains of mice receiving yogurt or acidophilus yogurt were higher than those of the mice in the control group. The mean values for serum cholesterol concentrations and LDL cholesterol concentrations were significantly decreased when acidophilus yogurt was fed on d 28 and 56. High density lipoprotein cholesterol and triglycerides were not affected by yogurt or acidophilus yogurt. The highest number of fecal lactobacilli was found in mice receiving acidophilus yogurt, and the number of fecal coliforms of that group was also lower than in the other two groups.
The possibility of using a commercial vegetable fat blend in Kashar cheese was investigated. Kashar cheeses were manufactured by replacing the milk fat (MF) with a vegetable fat (VF) blend. Kashar ...cheeses from whole milk were also manufactured to compare textural, microstructural, meltability, color and sensory characteristics during a ripening period of 90 days. The use of vegetable fat decreased the meltability, hardness, cohesiveness, gumminess and chewiness of the cheese; while increasing adhesiveness where springiness was not affected. Differences became less notable toward the end of ripening. Scanning electron micrographs displayed VF cheese with a compact network with small and uniform fat globules embedded in the protein matrix. The MF cheese exhibited an open protein matrix containing milk fat globules of various sizes and forms. The color analysis demonstrated significant differences between cheeses. Finally, all sensory characteristics of the cheese were affecte d by the vegetable fat blend.
Concentrations of thiamin were determined in pasteurized and UHT-sterilized milks, yoghurt and kefir samples by high-performance liquid chromatography using a reversed-phase C-18 column connected to ...fluorescence detector. The linearity, recovery and reproducibility of the method were satisfactory. The thiamin content ranged from 0.305±0.02 to 0.252±0.03 mg/l in market milks. Yoghurt samples had higher concentration of thiamin (0.355±0.04 and 0.404±0.02 mg/l) than values found in market milks. The least thiamin content was found in kefir (0.175±0.03 mg/l) among the samples analyzed.
Numerosos efectos fisiológicos se atribuyen a los ácidos linoléico conjugados (CLA). Así los isómeros biológicamente activos (cis-9, trans-11 y trans-10, cis-12) del ácido linoléico han sido ...descritos con propiedades anticarcinogénicas, antioxidantes y antiarterioscleróticas. Fuentes relativamente ricas de CLA incluyen alimentos con grasas lácteas tales como el kaymak. El kaymak es una crema concentrada elaborada de leche de búfalo o vaca principalmente en Turquía. El objetivo de este estudio fue la determinación de la concentración de CLA durante la producción de kaymak. El kaymak objeto de estudio fue elaborado a partir de leche de vaca que fue enriquecida con crema no fermentada. Los isómeros biológicamente activos del CLA fueron analizados por cromatografía gaseosa en leche cruda, crema y kaymak. El método empleado fue rápido, reproducible y sensible. Se encontraron diferencias significativas en las concentraciones de ambos isómeros y de CLA total durante el proceso de producción (p 0.01). Los contenidos totales de CLA para leche cruda, crema y kaymak fueron 0.08 +/- 0.02, 0.234 +/- 0.04 y 0.091 +/- 0.08 g/100 g de lípido, respectivamente.
Numerous physiological effects are attributed to conjugated linoleic acids (CLA). Biologically active isomers of CLA ( cis-9, trans-11 (C18:2) and trans-10, cis-12 (C18:2)) have been reported to have anticarcinogenic, antioxidative and antiatherosclerotic properties. Relatively rich sources of CLA include milk fat-containing foods such as kaymak. Kaymak is a kind of concentrated cream which is traditionally manufactured from buffalo or cow's milk mainly in Turkey . The objective of this study was to determine CLA concentrations during kaymak production. Kaymak was manufactured from cow's milk which was enriched with unfermented cream. Biologically active isomers of CLA in raw milk, cream and kaymak were analyzed using gas chromatography. The method was quick, repeatable and sensitive for the CLA determination of samples. Significant differences were found among the concentrations of both isomer and total CLA during the production process (p0.01). The total CLA contents of raw milk, cream and kaymak were determined as 0.08 +/- 0.02, 0.234 +/- 0.04 and 0.091 +/- 0.08 g/ 100 g lipid, respectively.
Reverse-phase HPLC was assessed for the determination of most important organic acids in Kargı Tulum cheese. The method with a simple treatment of the sample succeeded in eluting nine organic acids ...in a single chromatographic run with the aid of buffer-acetonitrile gradient. A gradient programme using a mobile phase of aqueous 0.5% (w/v) (NH₄)₂HPO₄-0.4% (v/v) acetonitrile at pH 2.24 was used to separate organic acids on a C₁₈ column. The best flow rate-time program was applied to take the chromatogram in 35 min with a high linearity and excellent repeatability. The main organic acids of Kargı Tulum cheese were lactic, acetic, citric, propionic and formic acids. Pyruvic, uric and orotic acids were found to be lower in content while butyric acid was not detected in the samples.
The complex MoO2Cl{HC(3,5-Me2pz)3}BF4 (1) (HC(3,5-Me2pz)3 = tris(3,5-dimethyl-1-pyrazolyl)methane) has been prepared and examined as a catalyst for epoxidation of olefins at 55 °C using tert-butyl ...hydroperoxide (TBHP) as the oxidant. For reaction of cis-cyclooctene, epoxycyclooctane is obtained quantitatively within 5 h when water is rigorously excluded from the reaction mixture. Increasing amounts of water in the reaction mixture lead to lower activities (without affecting product selectivity) and transformation of 1 into the trioxidomolybdenum(VI) complex {HC(3,5-Me2pz)3}MoO3 (4). Complex 4 was isolated as a microcrystalline solid by refluxing a suspension of 1 in water. The powder X-ray diffraction pattern of 4 can be indexed in the orthorhombic Pnma system, with a = 16.7349(5) Å, b = 13.6380(4) Å, and c = 7.8513(3) Å. Treatment of 1 in dichloromethane with excess TBHP led to isolation of the symmetrical Mo2O4(μ2-O){HC(3,5-Me2pz)3}2(BF4)2 (2) and unsymmetrical Mo2O3(O2)2(μ2-O)(H2O){HC(3,5-Me2pz)3} (3) oxido-bridged dimers, which were characterized by single-crystal X-ray diffraction. Complex 2 displays the well-known (Mo2O5)2+ bridging structure where each dioxidomolybdenum(VI) center is coordinated to three N atoms of the organic ligand and one μ2-bridging O atom. The unusual complex 3 comprises dioxido and oxidodiperoxo molybdenum(VI) centers linked by a μ2-bridging O atom, with the former center being coordinated to the tridentate N-ligand. The dinuclear complexes exhibit a similar catalytic performance to that found for mononuclear 1. For complexes 1 and 2 use of the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate and N-butyl-3-methylpyridinium tetrafluoroborate as solvents allowed the complexes to be completely dissolved, and in each case the catalyst and IL could be recycled and reused without loss of activity.
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