Skimmed Cow Milk Research Articles

Partial Coalescence in Cream‐Like Emulsions Prepared with Alternative Fats: Effect of Controlled Stirring and Temperature Cycles

AbstractThe objective was to study the partial coalescence as a consequence of controlled stirring and temperature cycles in oil‐in‐water emulsions prepared with skimmed cow milk and nondairy fats: low trans vegetable fat (LT), bovine fat (BF), partially hydrogenated soybean oil (HS) and sunflower oil as control. The partial coalescence rates (%/min) of the stirred emulsions were LT, 89.8 ± 4.3; BF, 29.7 ± 3.1; HS, 23.8 ± 3.1. This result was attributed to the lower solid fat content (%) of emulsion LT (19.2 ± 1.2 versus 25.9 ± 1.1 in BF and 56.8 ± 1.1 in HS). A temperature cycle with partial melting of fats led to hardening of texture in emulsions BF and HS due to partial coalescence, favored by the recrystallization of the fat at the interface. Emulsion LT did not show changes after the same treatment, probably because its lower solid fat content did not favor partial coalescence in the absence of mechanical work.Practical ApplicationsThis article deals with the formulation and characterization of cream‐like emulsions prepared with skimmed cow milk and different fats as an alternative lipid phase instead of dairy fat. The partial coalescence process was analyzed after application of controlled stirring (where the phenomenon is desired) and temperature cycles (where it must be avoided). This research can be useful as a starting point for the elaboration of a healthier product than dairy cream without losing its characteristic rheological behavior during whipping/stirring. This work also points to control some desired and undesired properties by the selection of the lipid phase. Promising results were obtained using a particular vegetable fat with low content of trans fatty acids; this may open the door for further investigations in order to obtain a healthy edible cream with favorable response to whipping/stirring and good stability against thermal fluctuations.

Effect of Different Types of Milk on Shelf Life and Microbial Quality of Rabri

Study was conducted to evaluate the effect of various four storage periods (0 day, 5 days, 10 days and 15 days) and four different types of milk (cow milk, buffalo milk, combined milk and skim milk) used for the preparation of Rabri. These samples were stored at 5˚C, and evaluated the three species of microorganisms (standard plate count X 105 Cfu/g, coliform count X 102 Cfu/g and yeast&mould count X 102 Cfu/g) which were noticed during storage. This evaluation process replicated thrice. The various storage periods and four different types of milk used for the preparation of Rabri, affected significantly at 0.1 % level of significance but the microbial populations were not affected significantly at 5% level of significance. The interaction between storage periods and milk, storage periods and microbes and milk and microbes significantly affected at the level of 0.1%. The overall interaction among storage period, milk and microbes found to be non-significant effect at 5% level of significance. The intensity of contamination was depending on types of milk and days of storage periods. The presence of total solids plays role in growth of microbes such as least number of cfu/g present in sample prepared by buffalo milk, whereas highest noticed in skim milk. The role of storage periods, as Rabri samples got old the intensity of contamination and growth of microbes increased. Least number of cfu /g noticed at 0 day and highest at 15 days of storage. The significant increase in SPC was observed after 10 to 15 days, but non-significant growth of coliform count and yeast mould count was noticed between 0 to 10 days of storage but growth was observed after 10 days of storage. It was recommended that the best quality of Rabri can be obtained by using buffalo milk at current day of preparation, the least microbial load was found at 0 to 10 days of storage but it would be remain consumable up to 15 days when it stored at 5˚C.

Effect of total milk solid content adjusted by adding ultrafiltered milk retentate on quality of set mango yoghurt

The quality of set mango yoghurt prepared by varying total milk solids (TMS) level in mango yoghurt mix, by adding 5× ultrafiltered cow skim milk retentate and cow milk cream, was investigated. The water‐holding capacity (WHC) and values of textural attributes of mango yoghurt increased, whereas body and texture and overall acceptability scores decreased significantly (P < 0.05) with increasing TMS level. The optimised product (10.2% TMS level) was compared with conventional mango yoghurt. Acetaldehyde concentration, WHC, values of textural attributes, body and texture, overall acceptability scores and pH were significantly (P < 0.05) higher in optimised compared with conventional mango yoghurt.

Soy milk as a storage medium to preserve human fibroblast cell viability: an in vitro study

Soy milk (SM) is widely consumed worldwide as a substitute for cow milk. It is a source of vitamins, carbohydrates and sugars, but its capacity to preserve cell viability has not been evaluated. The purpose of the present study was to investigate the efficacy of SM to maintain the viability of human fibroblasts at short periods compared with different cow milks. Human mouth fibroblasts were cultured and stored in the following media at room temperature: 10% Dulbecco's Modified Eagle Medium (DMEM) (positive control group); long shelf-life ultra-high temperature whole cow milk (WM); long shelf-life ultra-high temperature skim cow milk (SKM); powdered cow milk (PM); and soy milk (SM). After 5, 15, 30 and 45 min, cell viability was analyzed using the MTT assay. Data were analyzed statistically by the Kruskal-Wallis test with post-analysis using the Dunn's method (α=0.05). SKM showed the lowest capacity to maintain cell viability in all analyzed times (p<0.05). At 30 and 45 min, the absorbance levels in control group (DMEM) and SM were significantly higher than in SKM (p<0.05). Cell viability decreased along the time (5-45 min). The results indicate that SM can be used as a more adequate storage medium for avulsed teeth. SKM was not as effective in preserving cell viability as the cell culture medium and SM.

Performance of coiled tube ultraviolet reactors to inactivate Escherichia coli W1485 and Bacillus cereus endospores in raw cow milk and commercially processed skimmed cow milk

Two coiled tube reactors were designed to investigate the influence of Reynolds number (Re) and diameter of fluid carrying tube on UV-C inactivation of Escherichia coli W1485 and Bacillus cereus endospores in raw cow milk (RCM) and skimmed cow milk (SCM) at room temperature. UV reactors were constructed using perfluoroalkoxy (PFA) tubing having internal diameters of 1.6 and 3.2mm and each had a residence time of 11.3s. Four levels of Re were tested for each milk type, each tube size and each bacteria type. Inactivation efficiency increased as the Re increased in both the reactors for both types of milk. The inactivation of both bacteria was higher in the 1.6mm UV reactor than the 3.2mm UV reactor. Maximum reduction of 7.8log10CFU/ml of E. coli was achieved in SCM in the 1.6mm UV reactor corresponding to the Re of 532 and higher, whereas the maximum reduction of E. coli in RCM was 4.1log10CFU/ml at the highest level of Re (713) tested. For B. cereus, the maximum reduction was 2.72log10CFU/ml in 1.6 UV reactor, in SCM at Re of 1024; whereas the maximum reduction of B. cereus in RCM was 2.65log10CFU/ml at Re value of 713. Inactivation efficiency of both bacteria was more in SCM than RCM. The coiled tube reactor design provided adequate mixing and UV-C dosage for efficient disinfection of E. coli cells in milk.

Freezability of Tushin Ram Semen Extended with Goat or Cow Milk Based Extenders

Cow milk is used as an extender for ram semen cryopreservation. Caseins, the major proteins of milk, appear to provide some protective effect to sperm during cryopreservation. Goat milk has unique casein structure. The aim of this study was to investigate effect of goat milk, as a main semen extender, on freezability of Tushin Ram semen. For this aim, ejaculates from four Tushin rams were collected with artificial vagina and pooled. Pooled semen was separately extended with four different extenders: TRIS based (TRIS), cow skim milk based (CSM) (10 g/100 ml), cow semi-skim milk based (CSSM) and goat semi-skim milk based (GSSM) extenders, containing egg yolk and glycerol. The semen was cryopreserved and stored in liquid nitrogen until examination date. After thawing (at 37°C for 1 min), sperm motility, viability, morphology, acrosome and membrane integrity (HOST) were evaluated. Although, there was not any significant differences between extenders in post-thaw percentage of viable spermatozoa (p>0.05), Tushin ram semen extended with GSSM or CSM extenders had significantly higher post-thaw percentage of progressive motility (25.0% and 30.8% respectively), compared with CSSM and TRIS (7.5% and 14.1% respectively, p<0.001). Moreover, lowest abnormality percentage of post-thaw spermatozoa were detected in ram semen extended with GSSM (49.5%) and CSM (51.5%), compared with CSSM (65.7%) and TRIS (60.7%) (p<0.05). Whilst the results were considered, it was concluded that goat milk based extenders may be effectively and trustfully used in cryopreservation of Tushin ram semen, instead of cow milk and Tris based extenders, as a main extender.

ENHANCING OF MILK BEVERAGES

The effect of adding mango, guava pulp, total milk protein powder, skim milk powder, storage period and fat ratio on Chemical composition was investigated. Results revealed that the addition of mango and guava pulp to skim milk increased the acidity, total solids (T.S), reducing sugars (R.S), non reducing sugars (N.R.S) and viscosity of the final product. However it had a negligible effect on the total protein (T.P) and non protein nitrogen (N.P.N) of the final product. The increase in fat ratio caused an increase in total solids, total protein, non protein nitrogen, pH and viscosity. However decreased the acidity and it had no effect on reducing sugars (R.S) and non reducing sugars (N.R.S). The fortification of mango and guava - flavoured cow's skim milk beverages with total milk protein powder (retentate) and skim milk powder increased T.S, T.P, N.P.N, acidity and viscosity. On the other hand that fortification decreased the reducing sugars (R.S) and pH. Pasteurized beverages had a marked increase on R.S, N.P.N, acidity and viscosity, and a decrease in N.R.S and pH after storage on refrigerator condition up to 2 weeks. However, the changes in T.S and T.P during storage were slight.

Promotion of coconut in the production of yoghurt.

Yoghurt was produced from milk obtained from coconut milk and skimmed cow milk, by fermentation using starter cultures. The results obtained show that the pH of the various products ranged from 4.2 - 4.4. The acceptability of the yoghurt produced was investigated in a sensory evaluation study. The sensory evaluation study of the samples indicated that yogurt produced from skimmed cow milk did not differ from those produced from coconut and cow milk composites in all sensory quality attributes. Thus coconut milk can be used with cow milk to produce acceptable and affordable yoghurt since coconut milk is cheaper. The results also showed that middle aged coconut (7 - 8 months old) could be used for the production of acceptable yoghurt. Key words: Sensory evaluation, starter culture, coconut, substrate.

The Use of Tiger-Nut (Cyperus esculentus), Cow Milk and Their Composite as Substrates for Yoghurt Production

Yoghurt was produced from skimmed cow milk and tiger nut milk. The pH of the yoghurt was found to increase with increasing tiger nut milk in the composite. From the comparison made of the sensory attributes of the three samples of yoghurt composite, the yoghurt produced from the combination of cow milk and tiger nut milk had the highest mean score in all the parameters even though the difference between the means of cow milk-tiger nut composite and that of pure cow milk was insignificant. Thus the result of the sensory evaluation revealed that yoghurt from pure cow milk and the composite (tiger nuts milk and cow milk) were rated alike in almost all the quality attributes indicating the feasibility of adding tiger nut to cow milk in the production of cheaper and nutritious yoghurt.

Baroinactivation of Staphylococcus epidermidis - mathematical model and its verification using human and cow milk

&lt;I&gt;Staphylococcus epidermidis&lt;/I&gt;, commonly found on the human skin, may contaminate human milk. High-pressure pasteurisation of human milk under normal temperature preserves the majority of its protective agents. The objective of this study was to acquire baroinactivation data and develop a model for model solutions of pH = 6.4 to 7.2 and water activity a&lt;sub&gt;w&lt;/sub&gt; = 0.99, in which baroinactivation of &lt;I&gt;Staphylococcus epidermidis&lt;/I&gt; takes place. Decontamination data manifested exponential kinetics and the resulting model was described by the following equations: D&lt;sub&gt;p&lt;/sub&gt; = D&lt;sub&gt;p, ref&lt;/sub&gt; × 10 &lt;sup&gt;(Pref – P)/Z&lt;/sup&gt;, Z = –123.90 pH&lt;sup&gt;2&lt;/sup&gt; + 1635.54 pH – 5210.49; D&lt;sub&gt;p, ref&lt;/sub&gt; = –8.89 pH&lt;sup&gt;2&lt;/sup&gt; + 121.02 pH – 408.34. The developed model was verified using pasteurised human milk and UHT-treated skimmed cow milk. The agreement between the experimental data and model-based prediction was very good for human milk. It was proved that the application of a pressure of 350 MPa for 10 min decreased the concentration of the working suspension of &lt;I&gt;S. epidermidis&lt;/I&gt; in the model substrate by a minimum of five orders.

S100B Protein concentration in milk‐formulas for preterm and term infants Correlation with industrial preparation procedures

Human milk S100B protein possesses important neurotrophic properties. However, in some conditions human milk is substituted by milk formulas. The aims of the present study were: to assess S100B concentrations in milk formulas, to verify any differences in S100B levels between preterm and term infant formulas and to evaluate the impact of industrial preparation at predetermined phases on S100B content. Two different set of samples were tested: (i) commercial preterm (n = 36) and term (n = 36) infant milk formulas; ii) milk preterm (n = 10) and term infant (n = 10) formulas sampled at the following predetermined industrial preparation time points: skimmed cow milk (Time 0); after protein sources supplementation (Time 1); after pasteurization (Time 2); after spray-drying (Time 3). Our results showed that S100B concentration in preterm formulas were higher than in term ones (p < 0.01). In addition, S100B concentrations during industrial preparation showed a significant increase (p < 0.001) at Time 1 followed by a slight decrease (p > 0.05) at Time 2, whereas a significant (p < 0.001) dip was observed at Time 3. In conclusion, S100B showed a sufficient thermostability to resist pasteurization but not spry-drying. New feeding strategies in preterm and term infants are therefore warranted in order to preserve S100B protein during industrial preparation.

Effect of Physical and Chemical Treatments on Campylobacter Spiked into Food Samples

Campylobacter spp. were isolated from rivers Mula, Mutha and Pavana by preT-Kapadnis Baseri and Preston enrichment-modified charcoal cefoperazone deoxycholate agar methods. Survival studies were conducted in fresh skim cow milk, chicken meat extract and mushroom extract at various temperatures. The sensitivity of Campylobacter strains inoculated in the food samples, to chemical preservatives, gamma radiation, microwave heating and water bath heating was studied. Campylobacter strains survived well in milk and chicken extract; however, temperature significantly affected their survival in those food samples. Although most of the chemical preservatives were effective against Campylobacter isolates, the sub-inhibitory values of acetic acid and lactic acid were relatively lower against these isolates. All the strains investigated for the effect of gamma radiation, were sensitive to doses less than 3 kGy. In case of heat preservation, around 9 min was required to eliminate Campylobacter spp. by heating in water bath at 50°C while approximately 13 s from food samples exposed to heating in a microwave oven. The effect of food preservation techniques on Campylobacter varied with the temperature and type of the food. Microwave treatment appeared to be much more effective than water bath heating and that chicken meat extract conferred an additional protection to Campylobacter as compared to milk or PBS.

Physico-chemical and Sensory Evaluation of Ready to Drink Soy-cow Milk Blend

4 Abstract: Physico-chemical and sensory properties of ready to drink soy-cow milk blend were studied. Different processing techniques were applied to minimize beany flavour of soymilk. It was found that cooking of soybean in water having pH 8 at temperatures ranging from 90 to 100 C for 1h produced soymilk with mild o beany flavour. The astringency of soymilk was reduced by blending with cow skim milk powder. Minimum astringency of soymilk was noted in soymilk blended with 50-60% of cow skim milk powder. The overall acceptability of soy-cow milk blend improved with addition of fat and sugar.

Investigation of Process Characteristics and of Principal Components of Ultrafiltration Retentates

ABSTRACTAn investigation was made which aimed to establish the dry matter, protein and fat concentration factor and protein retention coefficient in retentates obtained by ultrafiltration of skim cow milk and protein/fat standardized cow milk intended for classic Bulgarian white brined cheese production. The skim and standardized milk ultrafiltration was carried out with a UF25-PAN polymeric membrane under the following operating conditions: working pressure Pwrk=0.4 MPa and volume reduction factor Kv=2 and Kv=3. The experiments demonstrated as follows: 1. An increase in the dry matter concentration factor of 1.37 and 1.8 times respectively when skim milk was used and 1.53 and 2.12 times respectively when milk standardized according to the protein/fat ratio was used; 2. An increase in the protein concentration factor of 1.84 and 2.72 respectively for skim milk and 1.83 and 2.71 for standardized milk; 3. An increase in the milk fat concentration factor of 1.74 and 2.91 respectively when standardized milk was used; 4. An increase in the protein retention coefficient values of 96.90 (Kv=2) and 97.90 (Kv=3) respectively for skim milk and 96.96 (Kv=2) and 97.91 (Kv=3) for standardized milk, which practically shows retention of all protein substances—casein and whey proteins—on the investigated membranes; 5. An increase in the protein relative share in the skim milk dry matter and the protein and fat relative share in the standardized milk dry matter at different volume reduction factors up to Kv=2 and Kv=3.

Comparative studies on the gelling properties of cardosins extracted from Cynara cardunculus and chymosin on cow's skim milk

A comparative study was developed on the clotting activities and gelling properties of cardosins A and B, extracted from dried flowers of Cynara cardunculus, and chymosin on cow's skim milk, at various pH values. The determination of the total milk-clotting activity was performed following an international standard, whereas a rheometer was employed to measure the viscoelastic properties of the gels subsequently formed: the evolution of the complex modulus (G*) and the phase angle (δ) was monitored with time. The G* values of the milk gels were higher for cardosins than for chymosin at pH 6.6, but the reverse held at pH 6.4 and 6.2. The δ values were identical for all three enzymes tested. Chymosin exhibited the highest specific milk clotting activity, followed by cardosin B. The clotting activity of chymosin seems to be more influenced than that of cardosins by the pH of milk.

ELISA test for the diagnosis of cysticercosis in pigs using antigens of Taenia solium and Taenia crassiceps cysticerci.

In the present study ELISA was standardized for the diagnosis of swine cysticercosis based on necropsy parameters and confirmed positive and negative control sera. Serum samples from pigs with other infections were also assayed to determine possible cross-reactions. Four antigens were assayed: from Taenia crassiceps vesicular fluid (VF-Tcra) and crude larvae extract (T-Tcra), and from Taenia solium extracts of scolex (S-Ts) and of larvae (T-Ts). A checkerboard evaluation of antigen, serum and conjugate dilutions, as well as the use of Tween-20 and skim cow milk in wash and blocking solution had a marked effect on improving ELISA performance. All the antigens showed a good performance, but VF-Tcra was the best, with 96.0% and 80.0% sensitivities for cut-offs respectively at 2sd and 3sd, and corresponding specificities of 97.5% and 100.0%. Cross-reactivity was observed only with hydatidosis and ascaridiosis. In view of the high performance observed, the ELISA test should be recommended for the diagnosis of cysticercosis in suspected swine in slaughterhouses and for the screening of cysticercosis in swine production. These results will support integrated measures of cysticercosis control throughout the chain of swine production, effectively contributing to public health.

Identification of Lactobacillus Species Associated with Selected African Fermented Foods

Abstract Two hundred isolates of Lactobacillus were obtained from seven indigenous fermented foods namely: 'fufu' (fermented cassava), 'iru' (fermented African locust bean), 'kenkey' and 'ogi' (fermented maize), 'kunu-zarki' (fermented millet), 'ugba' (fermented African oil bean) and 'wara' (fermented skimmed cow milk). Lactobacillus species identified were Lacto­ bacillus casei (17.0%), L. lactis (4.5%), L. plantarum (41.5%), L. brevis (11.5%), L. jensenii (5.5%), L. acidophilus (3.5%) L. cellobiosus (5.0%), L. delbrueckii (2.5%), L. salivarius (3.5%), L. leichmannii (3.5%) and L. fermentum (2.0%). The commonest species isolated was L. plantarum. This paper highlight the importance of Lactobacillus in the processing of African fermented foods.

Bacteriocin production by Enterococcus faecium NA01 from 'wara'--a fermented skimmed cow milk product from west Africa.

An Enterococcus faecium strain from Nigerian fermented skimmed cow milk ('wara') produced bacteriocin inhibitory towards Lactobacillus, Enterococcus and Listeria strains. The bacteriocin (designated enterocin 01) was inactivated by proteases, heat-stable at 100 degrees c and active at pH 2.0-6.0. The Ent. faecium isolate harboured plasmids of ca 36.3 and 23.1 kb. Curing experiments with ethidium bromide resulted in a bacteriocin-negative mutant which had not lost immunity to the bacteriocin. Slight differences in plasmid profiles between wild-type and mutant indicated a possible plasmid-coded bacteriocin production.

Effect of different diluents on Shami goat semen

Fifty semen samples from five healthy Shami bucks were diluted in six different diluents (egg yolk citrate (YC), egg yolk fructose phosphate (YFP), egg yolk citrate fructose glycine (YGC), egg yolk cow skim milk (YSKM), Illinois variable temperature extender (IVT), egg yolk tris fructose (YTF)). Semen was diluted in one step dilution, using a dilution rate of 1:!0, at 37°C and stored at 4°C Samples were evaluated at 0, 24, 48, 72, 96 and 120 h following dilution for motility rate, percent live sperm and percent damaged sperm. Best results were obtained with the YTF and IVT diluents after preservation to 120 h, with particular reference to individual motility (21.7%, 18.5%), percentage live sperm (24.1%, 20.0%) and sperm damage (33.4%, 31.7%, respectively). Data of the present study suggest that YTF and IVT diluents could be used to dilute and preserve Shami buck semen at 4°C.

Growth outcome and feeding practices of the very low birth weight infant (less than 1500 grams) within the first year of life

Growth outcome for 1 year of corrected age and feeding practices during that first year of life were described for a large population of very low birth weight (VLBW) infants. Growth patterns of weight, length, and occipitofrontal circumference through 12 months of corrected age, and weight/length ratios at 12 months, were determined for 122 VLBW infants less than or equal to 1500 gm and less than or equal to 35 weeks of gestational age at birth; feeding practices were surveyed within a subpopulation of 89 infants. Differences in growth were apparent when infants were grouped according to sex and appropriateness of intrauterine growth. When the mean values of each group were compared, the female infants of appropriate size for gestational age demonstrated growth at higher percentiles (National Center for Health Statistics term-infant norms) for all three measurements (weight, length, and occipitofrontal circumference). Male infants whose size was appropriate for gestational age, and male and female infants who were small for gestational age, all grew similarly, at lower percentiles for weight and length, when compared with the same norms. Growth in occipitofrontal circumference was closest to term infant norms in all subgroups of infants. The majority of the infants, regardless of subgroup, achieved weights and lengths greater than 5th percentile and proportionate growth with a normal weight/length ratio. At 12 months of corrected age, 30% remained at less than 5th percentile in weight, 21% in length, and 14% in occipitofrontal circumference. Eighteen infants (15%) had a marked discrepancy in weight for length, with a weight/length ratio less than 5th percentile. Three prevalent practices that could result in compromised nutrition were identified: (1) cereals were introduced at an early age, (2) 2% and skim cow milk were fed to approximately 50% of the infants within the first year of life, and (3) whole cow milk was introduced to some VLBW infants at an early age. Caretakers apparently viewed their infants in terms of chronologic age rather than age corrected for prematurity when it came to the initiation of solids and cow milk. Whether increased attention to appropriate feeding practices during the first year of life would result in a more favorable growth outcome for VLBW infants is not known.