Addition Of Dairy Products Research Articles

Genomic and Phenotypic Characterization of Mastitis-Causing Staphylococci and Probiotic Lactic Acid Bacteria Isolated from Raw Sheep's Milk.

Dairy products play a crucial role in human nutrition as they provide essential nutrients. However, the presence of diverse microorganisms in these products can pose challenges to food safety and quality. Here, we provide a comprehensive molecular characterization of a diverse collection of lactic acid bacteria (LAB) and staphylococci isolated from raw sheep's milk. Whole-genome sequencing, phenotypic characterization, and bioinformatics were employed to gain insight into the genetic composition and functional attributes of these bacteria. Bioinformatics analysis revealed the presence of various genetic elements. Important toxin-related genes in staphylococci that contribute to their pathogenic potential were identified and confirmed using phenotypic assays, while adherence-related genes, which are essential for attachment to host tissues, surfaces in the dairy environment, and the creation of biofilms, were also present. Interestingly, the Staphylococcus aureus isolates belonged to sequence type 5, which largely consists of methicillin-susceptible isolates that have been involved in severe nosocomial infections. Although genes encoding methicillin resistance were not identified, multiple resistance genes (RGs) conferring resistance to aminoglycosides, macrolides, and fluroquinolones were found. In contrast, LAB had few inherently present RGs and no virulence genes, suggesting their likely safe status as food additives in dairy products. LAB were also richer in bacteriocins and carbohydrate-active enzymes, indicating their potential to suppress pathogens and effectively utilize carbohydrate substrates, respectively. Additionally, mobile genetic elements, present in both LAB and staphylococci, may facilitate the acquisition and dissemination of genetic traits, including RGs, virulence genes, and metabolic factors, with implications for food quality and public health. The molecular and phenotypic characterization presented herein contributes to the effort to mitigate risks and infections (e.g., mastitis) and enhance the safety and quality of milk and products thereof.

Characterization and comparative genomic analysis of novel lytic bacteriophages targeting Cronobacter sakazakii

Cronobacter sakazakii, a foodborne pathogen, can contaminate powdered infant formula (PIF) and cause life-threatening meningitis, necrotizing colitis and meningoencephalitis in infants. Bacteriophages are increasingly considered an efficient approach to target pathogenic microorganisms. In the current study, four virulent phages that can infect C. sakazakii were isolated from sewage samples, and their biological and complete genomic characteristics were analyzed. A comparative genomic analysis was performed to investigate the functional genes and phylogenetic evolution of the four phages. The results revealed that all four phages belonged to the Ackermannviridae family. Notably, the viral burst size of the phages ranged from 10 to 250 PFU/cell, following a latent period of 5 min to 20 min. Moreover, phages were stable over a pH range of 4 to 10 and a temperature range of 50 ℃ to 60 ℃. The full length of the complete genomes of the four phages ranged from 41,929 bp to 146,806 bp, containing lysis genes but no virulence genes. Phylogenetic tree analysis showed that the four phages were members of two distinct genetic groups with a significant genetic evolutionary distance between each C. sakazakii phage. Furthermore, the antibacterial assay revealed that all phages could inhibit the growth of C. sakazakii for up to 24 h. Taken together, the four phages have huge prospects as additives in dairy products to counter C. sakazakii.

Processing properties of yogurt as affected by the EPS produced by Leuconostoc mesenteroides XR1

SummaryThe aim of this study was to examine the fermentation characteristics of a novel Leuconostoc mesenteroides strain (XR1) and to investigate the effect of XR1 exopolysaccharides (EPS) on the microstructure, texture and rheological properties of yoghurt. The novel Leuconostoc mesenteroides strain (XR1) was isolated from wild kefir grains obtained from Xinjiang Province. The results showed that XR1 had good EPS production capacity and favourable fermentation performance. The addition of XR1 EPS to fermented milk effectively improved the water‐holding capacity (WHC) of the fermented milk and changed its microstructure. In subsequent fermentation studies, the XR1 strain was found to be a compatible strain, and the steric barrier formed between XR1 EPS and the fermented milk proteins enhanced its viscoelastic properties. Rheology studies indicated that fermented milk supplemented with EPS possessed a higher modulus (G’, G’’ ) and complex viscosity. Thus, these results indicate that XR1 EPS are useful as a natural organic additive that can replace chemical additives in dairy products.

Analysis of physicochemical properties of exopolysaccharide from Leuconostoc mesenteroides strain XR1 and its application in fermented milk

Studies regarding the effects of extracellular polysaccharides produced by high-quality Kefiran production strains on the quality of yoghurt products and the mechanism of action during fermentation and production of yoghurt products are scarce in the literature. However, these studies are highly significant in the development of starters for the yoghurt industry. In this study, a Leuconostoc mesenteroides XR1 strain that produced exopolysaccharides (EPS) was identified and isolated from kefir grains collected from Xinjiang, China. XR1-EPS has similar flocculation characteristics to xanthan gum and higher emulsifying activity than locust gum. A rheological test of the dairy product sample after fermentation of XR1 single bacteria proved that XR1-EPS can impart higher viscosity and elasticity to fermented milk. Results also showed that XR1-EPS can maintain the water-holding ability of the fermented milk and provide a positive thixotropic fluid. In this study, XR1-EPS was isolated in the laboratory for the first time and was shown to be useful as a natural organic additive that can replace chemical additives in dairy products.

Исследование влияния амарантовой муки и белковой основы эмульсионного геля на качество заварного крема

The article presents the results of research on the development of custard technology using amaranth flour, starch complex, sunflower oil and protein-polysaccharide mixture (BPS). To enrich the custard, instead of butter, sunflower oil was introduced, which is a source of vitamin E and essential fatty acids (linoleic and linolenic), does not contain cholesterol, and also serves as a source of energy and plastic material for humans. Soy protein isolate and dry whey were intended as a protein in BPS, and sodium alginate, gum arabic and pectin were intended as polysaccharides. On the basis of physical and chemical studies, the optimal combinations of polysaccharides, the percentage of amaranth flour and starch in the cream have been established. It was found that soy-based protein has better physicochemical and organoleptic characteristics in comparison with whey. Research results show that encapsulation in BPS improves the structure of the cream, reduces the density and cost of the product. Custard recipes have been developed based on soy protein isolate and whey powder, with the addition of vegetable oil and amaranth flour. The use of encapsulation allows you to enrich the product with useful oils and dietary fiber. A functional product has been obtained, without the addition of dairy products and wheat flour.

Enrichment of milk ice cream with bee products

The article is devoted to the development of enriched diet ice cream technology for a wide range of consumers. The analysis of numerous literature on functional enrichment components determined the relevance of the use of products of biological origin. In this regard, organoleptic and physico-chemical studies of milk ice cream were obtained using the technology, which provides for the inclusion in the formulation of beekeeping products - bee pollen - pollen and water propolis extract. The choice of these components is explained by the high content of amino acids, vitamins, minerals, enzymes and other biologically active substances. The mass fraction of fat and sucrose solids in the product was controlled by traditional methods according to GOST, and organoleptic evaluation was carried out by consistency, structure and taste. The paper gives the rationale for the use of additives, and also determines the optimal dose for making milk ice cream. It was found that the introduction of propolis is recommended in an amount of 0.6%, bee pollen in an amount of 1.0%. These dosages did not impair organoleptic and physico-chemical parameters, but at the same time allowed enriching the product with biologically valuable components. In the future, it is planned to expand research on the use of food additives in dairy products for the functional enrichment of their composition.

The Effect of Slaughter Age and the Diet in the Final Growth Phase of Poulards on Productivity and Meat Quality

Abstract The aim of the studies was to evaluate the effect of the diet in the final growth phase and slaughter age of poulards on productivity, dressing percentage, carcass colour and physicochemical properties of meat. The studies were conducted on 78 hybrids obtained by crossing Ross 308 broiler roosters with Rhode Island Red (R-11) dual-purpose laying hens (♂Ross 308 × ♀R-11). Birds were assigned to 3 groups: control group (K) fed starter, grower and finisher diets without addition of dairy products, experimental group S offered a finisher diet supplemented with 4% whey, and experimental group M receiving 4% milk powder supplement in the final growth phase. Spaying procedure was carried out at 8 weeks of age. Poulards were slaughtered at 18 and 20 weeks of age. The studies showed that by using hybrids of dual-purpose hens with broiler roosters for production of poulards, rearing period could be shortened to 18 weeks, and the obtained meat had comparable or even better quality traits compared with poulards slaughtered at 20 weeks of age. Supplementation of poulard diet with 4% whey or milk powder in the final growth phase had a beneficial effect mostly on improvement of sensory properties of meat. There were not many significant differences in meat quality between poulards fed the diet supplemented with milk and whey but instead there were differences between these groups and the control group fed the diet without these additives.

Nonfat milk attenuates acute hyperglycemia in individuals with android obesity: A randomized control trial.

BackgroundElevated android body fat increases the risk of developing cardiometabolic diseases. Postprandial hyperglycemia contributes to the proatherogenic metabolic state evident in android adiposity. Due to the insulinotropic effect of milk‐derived proteins, postprandial hyperglycemia has been shown to be reduced with the addition of dairy products. The purpose of this study was to determine whether one serving of nonfat milk added to an oral glucose tolerance test (OGTT) could attenuate postprandial hyperglycemia in individuals with elevated android adiposity and whether these improvements would be associated with metabolic and/or peripheral hemodynamic effects.MethodsIn this placebo‐controlled, randomized, crossover experimental study, 29 overweight/obese adults (26 ± 1 year) consumed an OGTT beverage (75 g glucose) combined with either nonfat milk (227 g) or a placebo control (12 g lactose + 8 g protein + 207 g water) that was matched for both carbohydrate and protein quantities.ResultsIn the whole sample, blood glucose and insulin concentrations increased over time in both trials with no significant differences between trials. Relative increases in peak blood glucose response were significantly related to android body fat (p < 0.05). The subjects in the highest tertiles of android body fat displayed attenuated hyperglycemic responses as well as improvements in flow‐mediated dilation (FMD) after milk intake.ConclusionsA single serving of nonfat milk may attenuate acute hyperglycemia in individuals with elevated android body fat offering a simple and convenient option for managing elevations in blood glucose.

Simultaneous quantification of five proteins and seven additives in dairy products with a heart-cutting two-dimensional liquid chromatography method.

A heart-cutting two-dimensional high-performance liquid chromatography method was developed to simultaneously quantify five major proteins and seven food additives (maltol, ethyl maltol, vanillin, ethyl vanillin, benzoic acid, sorbic acid, and saccharin sodium) in milk and milk powders. In this two-dimensional system, a Venusil XBP-C4 column was selected in the first dimension for protein separation, and a Hypersil ODS-2 C18 column was employed in the second dimension for additive separation; a two-position, six-port switching valve was used to transfer the targets (additives) from the first dimension to the second dimension. Method validation consisted of selectivity, response function, linearity, precision, sensitivity, and recovery. In addition, a conventional one-dimensional high-performance liquid chromatography method was also tested for comparison. The two-dimensional method resulted in significantly improved recovery of the food additives compared to the conventional method (90.6-105.4% and 65.5-86.5%, respectively). Furthermore, this novel method has a simple one-step sample preparation procedure, which shortens the analysis time, resulting in more efficient analysis and less solvent usage.

Rapid detection of melamine in milk liquid and powder by surface-enhanced Raman scattering substrate array

To determine the artificial additives in dairy products, we demonstrate a simple method for rapid and massive determination of melamine in milk liquid and powder samples by surface-enhanced Raman spectroscopy (SERS) technique. The developed method utilizes silver nanoparticles (AgNPs) decorated on a cylindrical support for detecting as low as 5 μL of sample without any drying procedure. Importantly, the linear range for melamine in water was 5–400 parts per billion (ppb) with a low detection limit of 2.5 ppb (S/N = 3). In addition, for analysis of melamine in milk liquid and powder, the dilution method was successfully applied to suppress the matrix effect from real samples. Interestingly, our results indicate that a dilution factor of 75 could effectively reduce the matrix effect with partially sacrificing the sensitivity in detection. The detection limit is increased to 2 parts per million (ppm) in real sample detection, which is close to the acceptable limits regulated in milk products. More importantly, the elimination of complicated sample pre-treatments and the acceptable sensitivity in melamine detection attest our proposed method as a potential tool for rapid and massive food inspections.

Analysis of additives in dairy products by liquid chromatography coupled to quadrupole-orbitrap mass spectrometry

A new method combining QuEChERS with ultrahigh-performance liquid chromatography and electrospray ionization quadrupole Orbitrap high-resolution mass spectrometry (UHPLC/ESI Q-Orbitrap) was developed for the highly accurate and sensitive screening of 43 antioxidants, preservatives and synthetic sweeteners in dairy products. Response surface methodology was employed to optimize a quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation method for the determination of 42 different analytes in dairy products for the first time. After optimization, the maximum predicted recovery was 99.33% rate for aspartame under the optimized conditions of 10mL acetionitrile, 1.52g sodium acetate, 410mg PSA and 404mgC18. For the matrices studied, the recovery rates of the other 42 compounds ranged from 89.4% to 108.2%, with coefficient of variation <6.4%. UHPLC/ESI Q-Orbitrap Mass full scan mode acquired full MS data was used to identify and quantify additives, and data-dependent scan mode obtained fragment ion spectra for confirmation. The mass accuracy typically obtained is routinely better than 1.5ppm, and only need to calibrate once a week. The 43 compounds behave dynamic in the range 0.001–1000μgkg−1 concentration, with correlation coefficient >0.999. The limits of detection for the analytes are in the range 0.0001–3.6μgkg−1. This method has been successfully applied on screening of antioxidants, preservatives and synthetic sweeteners in commercial dairy product samples, and it is very useful for fast screening of different food additives.

Fundamental Elements to Produce Sesame Yoghurt from Sesame Milk

Problem statement: In previous work sesame milk was developed. The developed milk had slightly acceptable flavor and limited shelf life. Fermentation of sesame milk is one way to overcome these problems. Approach: Sesame yoghurt experiments were carried out using pasteurized sesame milk (75°C for 5 min) with 14% initial sesame seed concentration and 2.7% glucose with different dairy products: lactose, Cheese Dried Whey (CDW), Non Fat Dried Milk (NFDM) and skim milk. The formulas were fermented using commercial yoghurt starter culture for different times. Results: The texture of all resulted yoghurt lacked the typical set yoghurt body and was similar to that of drinking yoghurt. The best formula was sesame milk with 2% CDW followed by sesame milk with 2% NFDM and then by sesame milk extended with skim milk in a ratio of 1:1. The optimum fermentation times were 6, 8 and 8 h respectively. Conclusion/Recommendations: The addition of dairy products was essential to promote acid and flavor development.

Separation and determination of trace amounts of some plastic additives in dairy products

Packing milk products in air-tight polyethylene containers is widely used for long-term storage. However, polyethylene will contain phenolic antioxidants which may tend to migrate into the milk. A TLC method has been developed to detect in the complex milk matrix traces of l,6-hexanediol-bis-3-(3,5-di-tert. butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis[3-(3,5-di-tert. butyl-4-hydroxyphenyl) propionate] and 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert. butyl-4-hydroxyphenyl) benzene. By solvent extraction of the pretreated milk, the accidental additives together with the milk fat are separated from the aqueous phase. The extractant is evaporated and the residue dissolved in chloroform. Aliquots of this solution together with standard solutions are spotted on pretreated TLC or HPTLC plates. After development of the plates the phenolic substances are revealed by the Boute reaction. Quantitative measuremerits are obtained by using a TLC scanner at 405 nm. Orientative experiments on migration of one of the additives from HDPE into milk and other extractants have been performed and the results compared with those obtained from radioactive labelling techniques.