Membrane filtration of dairy products for microbiological analysis.

Incubation with protease or Tween 80 or both dramatically improved the membrane filterability of liquid milks, powdered skim milk, and frozen dairy products without reducing the viability of five common species of bacteria. The technique can permit isolation and enumeration of microorganisms from test samples of these foods as large as 5 g. Flow direction through the filter was an important factor in filterability of dairy products.     

Filtration, haze and foam characteristics of fermented wort mediated by yeast strain

AIMS: To investigate the influence of the choice of yeast strain on the haze, shelf life, filterability and foam quality characteristics of fermented products. METHODS AND RESULTS: Twelve strains were used to ferment a chemically defined wort and hopped ale or stout wort. Fermented products were assessed for foam using the Rudin apparatus, and filterability and haze characteristics using the European Brewing Convention methods, to reveal differences in these parameters as a consequence of the choice of yeast strain and growth medium. CONCLUSIONS: Under the conditions used, the choice of strain of Saccharomyces cerevisiae effecting the primary fermentation has an impact on all of the parameters investigated, most notably when the fermentation medium is devoid of macromolecular material. SIGNIFICANCE AND IMPACT OF THE STUDY: The filtration of fermented products has a large cost implication for many brewers and wine makers, and the haze of the resulting filtrate is a key quality criterion. Also of importance to the quality of beer and some wines is the foaming and head retention of these beverages. The foam characteristics, filterability and potential for haze formation in a fermented product have long been known to be dependant on the raw materials used, as well as other production parameters. The choice of Saccharomyces cerevisiae strain used to ferment has itself been shown here to influence these parameters.     

Evaluation of water footprint and economic water productivities of dairy products of South Africa

Assessment of water footprint sustainability indicators and economic water productivities is regarded as a cornerstone of the world’s sustainability goal and the reduction of the fresh water scarcity risk. These assessments are gaining much prominence because about four billion people face severe water scarcity, globally. Attaining sustainable and economically efficient water use goals requires a thorough assessment of all the existing sectors that use water. This paper examined the water footprint and economic water productivities of dairy products in South Africa for the periods 1996–2005 and 2006–2013 using the water footprint network assessment methodology. We found the total water footprints of all the selected dairy products in South Africa to be higher than the global averages are. During the period of 1996–2005, South African dairy producers utilized more green water in their dairy production. The production of butter and cheese products, whether grated or not grated, powdered or not powdered, blue-veined and cheese of all kinds had the highest total water footprints among all the dairy products in South Africa. Dairy production under a sole grazing system has high water footprints and low economic water productivities, relative to mixed production systems, for the period 2006–2013. With blue water becoming scarcer in South Africa, it is time for dairy livestock producers to shift their production to a system that is highly productive and has low water footprints. The water footprints of most of the dairy products for period 2006–2013 have reduced by varying amounts, relative to 1996–2005, which shows that water users along the dairy industry chains are managing water cautiously. Our findings have revealed dairy products that have high economic water productivities, and suggest that profit maximising and environmentally sustainable dairy producers and water users should integrate both blue water sustainability and economic water productivity indicators in their production decisions.     

Blood filterability in peripheral obstructive arterial disease

The aim of this paper is to test whether an alteration of blood flow in microcirculation and in particular of red cell deformability is present in chronic arterial occlusive disease. To this end we determined by the method proposed by Reid and Dormandy (J. Clin. Pharmacol. 1976, 29, 855) whole-blood filterability in 18 patients with peripheral vascular disease, in 15 clinically healthy subjects and in 99 subjects without clinical evidence of ischemic pathology displaying one or more vascular risk factors. Blood filterability turned out to be significantly lower in cases of arterial disease that in the controls (p less than 0,001), and we found a constant reduction of blood filterability with the increase of number of risk factors. Comparison of the results obtained in arteriopatics and in controls displaying risk factors shows that though risk factors have an important impact on blood filterability, their presence alone is not enough to explain the reduction of blood filterability which, risk factors being equal, in vascular disease is always significantly lower than in controls. We also found a significant correlation between levels of fibrinogen and reduction of blood filterability.     

Menstrum for culture preservation and medium for seed preparation in a tetanus toxin production process containing no animal or dairy products

AIMS: To completely eliminate animal and dairy products from the lyophilization menstrum and the seed medium used to produce tetanus toxin with Clostridium tetani. METHODS AND RESULTS: Tetanus toxin production in a recently developed fermentation medium lacking animal and dairy products was studied with different seed media. It was found that soy peptone could completely replace the beef heart infusion plus animal peptone previously used as seed medium. In addition, we found that cells lyophilized in soy milk could replace the usual type of cells lyophilized in cow's milk. CONCLUSIONS: We have now developed a complete tetanus toxin production process containing no animal and dairy products. SIGNIFICANCE AND IMPACT OF THE STUDY: Toxoid preparations made from toxin produced with animal and dairy products can contain undesirable contaminants such as the prion causing bovine spongiform encephalopathy (Mad Cow's Disease) or antigenic peptides that stimulate anaphylactic reactions and other undesirable immune reactions in immunized hosts. The new vegetable-based process described here avoids such unfortunate possibilities.     

Dairy products and cardiovascular disease

PURPOSE OF REVIEW: Although it has often been postulated that the consumption of dairy products is associated with a high risk of coronary heart disease, study results have been conflicting. This review summarizes recent observational and human intervention trial findings on dairy products and cardiovascular disease. RECENT FINDINGS: Results from more recent observational studies on dairy products and milk disagree. This may be because of the very different methods used combined with several methodological problems. A somewhat surprising beneficial association between the intake of dairy products and the metabolic syndrome was observed in some studies, although not in a single study of elderly women. Milk may have the same cholesterol-raising properties as butter, whereas cheese does not seem to increase plasma cholesterol. Some milk products fermented by specific bacterial strains have been shown to have rather moderate cholesterol-reducing properties. There is also good evidence that certain fermented products (especially by Lactobacillus helveticus) have a mildly decreasing effect on hypertension, probably because of bioactive peptides. SUMMARY: When guiding principles such as balance, variety and moderation are stressed, there is no strong evidence that dairy products increase the risk of coronary heart disease in healthy men of all ages or young and middle-aged healthy women. Human studies should investigate the role of dairy products with respect to sex and age by including classic and novel risk markers of coronary heart disease. Specific fermented milks may be beneficial in the future prevention of hypertension. The beneficially neutral effect of cheese on coronary heart disease risk factors should be elucidated further.     

Iodine in plant-based dairy products is not sufficient in the UK: A market survey

BackgroundFollowing a well-balanced diet ensures that a person gets all the essential elements for health sustenance. However, in the United Kingdom an increasing proportion of people are transiting to become vegans who exclude animal-based products in their diets. Consequently, people may have a deficit of essential elements such as iodine which is not present in most plant-based meals, additionally iodide fortified table salt is not commonly used in the UK. Without iodine people consuming a vegan diet risk developing iodine deficiency and diseases like goiter.MethodsThe objective of this study is to determine the difference in iodine content and iodine speciation between plant-based and dairy products. More than 100 market samples of plant-based and dairy milk products were collected in Scotland, UK.ResultsIodine concentrations in dairy milk is ten times higher compared to plant-based milks. Similar differences were also apparent for butter, yogurt and cheese. A total of 20% of plant-based milk products were fortified with iodine, however these products had lower iodine concentrations compare to the equivalent dairy products. In this study we calculated that people with average diet have an iodine intake of 226 + /- 103 μg day⁻¹ from dairy products which satisfies the WHO recommended intake of adults and 90% of the recommend intake for pregnant and breast-feeding women. A diet from substituted dairy products gives only 21.8 µg day⁻¹ for the respective WHO guideline intake values, which accounts only 15% of the iodine intake for adults and 9% for pregnant and lactating women. Iodine fortified diet could increase the iodine intake to 55% or 33% of the WHO recommended daily intake respectively.ConclusionPlant-based dairy consumers are encouraged to use iodine fortified dairy products or use of iodized salt in the UK for home cooking, otherwise there are at risk to get iodine deficient.     

Deformability investigations of erythrocytes stored at different temperatures

The deformability changes of erythrocytes stored at different temperatures were characterized by a filtration procedure. The filterability index (FI) of erythrocytes cryopreserved at either -196 degrees C or -28 degrees C increased (deformability decreased) by about 9% and 40% respectively. For comparison with the cryopreserves the filterability of erythrocytes stored in liquid state at +4 degrees C were investigated. The filterability changes are discussed in comparison with the changes of MCHC during storage.     

Homocysteinylation score of high-molecular weight plasma proteins

Ultrafiltration rates (filterability) of protein-bound homocysteine (Hcy), unlike glutathione (Glt), are significantly decreased in patients with cardiovascular disorders, end-stage renal disease, and prothrombotic conditions. Reduced filterability of Hcy through 300,000 MWCO PES membranes in these groups of patients was observed, regardless of hyperhomocysteinemia (HHcy) degree. Filterability of Hcy, but not of glutathione, was impaired in plasma preparations. It is possible that the patients with impaired filterability of Hcy in mixed disulfide state are characterized by increased ability of partial Hcy retention by proteins and complexes with higher than albumin molecular weight. These findings led us to conclude that evaluation of protein-bound Hcy filterability may provide more complete diagnostic data, to interpret clinical significance of HHcy. The proposed Hcy filterability test may be performed as a simple laboratory procedure, in addition to conventional tests for total Hcy.     

Dairy products and physical stature: A systematic review and meta-analysis of controlled trials

The positive relationship between per capita availability of dairy products and average height found in historical studies (for instance in nineteenth century Bavaria, Prussia and France; Baten, 2009) does not necessarily indicate a causal relationship. Historical studies usually apply non-experimental methods that may produce substantial bias. Modern experimental controlled studies may provide high quality evidence supporting a causal relationship between consumption of dairy products and physical growth. This paper provides a systematic review and meta-analysis of controlled trials investigating the effect of supplementing usual diet with dairy products on physical growth. Twelve studies provided sufficient, independent data for meta-analysis. Seven studies were conducted since the 1990s. The other studies were conducted between 1926 and 1980. Studies were conducted in Europe, USA, China, Northern Vietnam, Kenya, Indonesia and India. Many studies had some internal validity problems such as lack of randomisation or dissimilarity of groups at baseline regarding height and age, which affects the quality of evidence.Meta-analysis and sensitivity analysis showed that the most likely effect of dairy products supplementation is 0.4 cm per annum additional growth per ca 245 ml of milk daily. Meta-regression analysis indicated that milk might have more effect on growth than other dairy products while lower height-for-age and being a teenager increased the effect of supplementation.In conclusion, there is moderate quality evidence that dairy products supplementation stimulate linear growth supporting hypotheses that changing levels of consumption of dairy products in the 19th and 20th centuries contributed to trends in height.     

Increased sensitivity of the rapid hydrophobic grid membrane filter enzyme-labeled antibody procedure for Escherichia coli O157 detection in foods and bovine feces

Several strains of Escherichia coli O157:H7 artificially inoculated into vegetables and dairy products were recovered on hydrophobic grid membrane filters and enumerated by an enzyme-labeled antibody assay. The mean of the recoveries from 12 fresh vegetables was 108.8%, whereas that from 10 dairy products was 93.2%. Modified tryptic soy broth at 43 degrees C with shaking at 100 rpm provided optimum recovery of the organism from meat, with a sensitivity of less than or equal to 1 CFU/g, which is 10 times more sensitive than direct plating. The method performed equally well with vegetable and dairy products. Tryptic soy broth, however, under the same conditions gave the best results for fecal samples. Of 22 asymptomatic dairy cattle, reported as having positive Brucella titers when assayed with polyclonal antibodies, eight were found to contain E. coli O157 in their feces as demonstrated by the enzyme-labeled antibody assay by using monoclonal antibodies. This finding may explain some of the false-positive Brucella tests.     

Increased sensitivity of the rapid hydrophobic grid membrane filter enzyme-labeled antibody procedure for Escherichia coli O157 detection in foods and bovine feces.

Several strains of Escherichia coli O157:H7 artificially inoculated into vegetables and dairy products were recovered on hydrophobic grid membrane filters and enumerated by an enzyme-labeled antibody assay. The mean of the recoveries from 12 fresh vegetables was 108.8%, whereas that from 10 dairy products was 93.2%. Modified tryptic soy broth at 43 degrees C with shaking at 100 rpm provided optimum recovery of the organism from meat, with a sensitivity of less than or equal to 1 CFU/g, which is 10 times more sensitive than direct plating. The method performed equally well with vegetable and dairy products. Tryptic soy broth, however, under the same conditions gave the best results for fecal samples. Of 22 asymptomatic dairy cattle, reported as having positive Brucella titers when assayed with polyclonal antibodies, eight were found to contain E. coli O157 in their feces as demonstrated by the enzyme-labeled antibody assay by using monoclonal antibodies. This finding may explain some of the false-positive Brucella tests.     

Deformability characterization of erythrocytes stored in different resuspension media

The deformability changes of erythrocytes during 35 days of storage in different resuspension media were characterized by a filtration procedure. The filterability of erythrocytes stored in CDS-AG medium decreased drastically, whereas the filterability of erythrocytes stored in SAGM and SAGS medium decreased only slightly. The MCHC change of stored erythrocytes were discussed in relation to filterability effects.     

The growth of Bacillus stearothermophilus on stainless steel

AIMS: To determine the potential for Bacillus stearothermophilus cells to form biofilms of significance in dairy manufacture. METHODS AND RESULTS: The ability of isolates of B. stearothermophilus from dairy manufacturing plants to attach to stainless steel surfaces was demonstrated by exposing stainless steel samples to suspensions of spores or vegetative cells and determining the numbers attaching using impedance microbiology. Spores attached more readily than vegetative cells. The attachment of cells to stainless steel was increased 10-100-fold by the presence of milk fouling the stainless steel. The growth of B. stearothermophilus as a biofilm on stainless steel surfaces was determined using a continuously flowing experimental reactor. Vegetative cells were released in greater numbers than spores from biofilms of most strains studied. Biofilms of one strain (B11) were studied in detail. Biofilms of > 106 cells cm-2 formed in the reactor and released approximately 106 cells ml-1 into milk passing over the biofilm. A doubling time of 25 min was calculated for this organism grown as a biofilm. CONCLUSION: The formation of biofilms of thermophilic Bacillus species within the plant appears to be a likely cause of contamination of manufactured dairy products. Methods to control the formation of biofilms in dairy manufacturing plants are required to reduce the contamination of dairy products with thermophilic bacilli. SIGNIFICANCE AND IMPACT OF THE STUDY: Biofilms of B. stearothermophilus growing in dairy manufacturing plants can explain the contamination of dairy products with these bacteria.     

Biomarker of food intake for assessing the consumption of dairy and egg products

Dairy and egg products constitute an important part of Western diets as they represent an excellent source of high-quality proteins, vitamins, minerals and fats. Dairy and egg products are highly diverse and their associations with a range of nutritional and health outcomes are therefore heterogeneous. Such associations are also often weak or debated due to the difficulty in establishing correct assessments of dietary intake. Therefore, in order to better characterize associations between the consumption of these foods and health outcomes, it is important to identify reliable biomarkers of their intake. Biomarkers of food intake (BFIs) provide an accurate measure of intake, which is independent of the memory and sincerity of the subjects as well as of their knowledge about the consumed foods. We have, therefore, conducted a systematic search of the scientific literature to evaluate the current status of potential BFIs for dairy products and BFIs for egg products commonly consumed in Europe. Strikingly, only a limited number of compounds have been reported as markers for the intake of these products and none of them have been sufficiently validated. A series of challenges hinders the identification and validation of BFI for dairy and egg products, in particular, the heterogeneous composition of these foods and the lack of specificity of the markers identified so far. Further studies are, therefore, necessary to validate these compounds and to discover new candidate BFIs. Untargeted metabolomic strategies may allow the identification of novel biomarkers, which, when taken separately or in combination, could be used to assess the intake of dairy and egg products.     

Identification of the bacterial microflora in dairy products by temporal temperature gradient gel electrophoresis

Numerous microorganisms, including bacteria, yeasts, and molds, are present in cheeses, forming a complex ecosystem. Among these organisms, bacteria are responsible for most of the physicochemical and aromatic transformations that are intrinsic to the cheesemaking process. Identification of the bacteria that constitute the cheese ecosystem is essential for understanding their individual contributions to cheese production. We used temporal temperature gradient gel electrophoresis (TTGE) to identify different bacterial species present in several dairy products, including members of the genera Lactobacillus, Lactococcus, Leuconostoc, Enterococcus, Pediococcus, Streptococcus, and STAPHYLOCOCCUS: The TTGE technique is based on electrophoretic separation of 16S ribosomal DNA (rDNA) fragments by using a temperature gradient. It was optimized to reveal differences in the 16S rDNA V3 regions of bacteria with low-G+C-content genomes. Using multiple control strains, we first set up a species database in which each species (or group of species) was characterized by a specific TTGE fingerprint. TTGE was then applied to controlled dairy ecosystems with defined compositions, including liquid (starter), semisolid (home-made fermented milk), and solid (miniature cheese models) matrices. Finally, the potential of TTGE to describe the bacterial microflora of unknown ecosystems was tested with various commercial dairy products. Subspecies, species, or groups of species of lactic acid bacteria were distinguished in dairy samples. In conclusion, TTGE was shown to distinguish bacterial species in vitro, as well as in both liquid and solid dairy products.     

Preventive Effects of a Fermented Dairy Product against Alzheimer’s Disease and Identification of a Novel Oleamide with Enhanced Microglial Phagocytosis and Anti-Inflammatory Activity

Despite the ever-increasing number of patients with dementia worldwide, fundamental therapeutic approaches to this condition have not been established. Epidemiological studies suggest that intake of fermented dairy products prevents cognitive decline in the elderly. However, the active compounds responsible for the effect remain to be elucidated. The present study aims to elucidate the preventive effects of dairy products on Alzheimer’s disease and to identify the responsible component. Here, in a mouse model of Alzheimer’s disease (5xFAD), intake of a dairy product fermented with Penicillium candidum had preventive effects on the disease by reducing the accumulation of amyloid β (Aβ) and hippocampal inflammation (TNF-α and MIP-1α production), and enhancing hippocampal neurotrophic factors (BDNF and GDNF). A search for preventive substances in the fermented dairy product identified oleamide as a novel dual-active component that enhanced microglial Aβ phagocytosis and anti-inflammatory activity towards LPS stimulation in vitro and in vivo. During the fermentation, oleamide was synthesized from oleic acid, which is an abundant component of general dairy products owing to lipase enzymatic amidation. The present study has demonstrated the preventive effect of dairy products on Alzheimer’s disease, which was previously reported only epidemiologically. Moreover, oleamide has been identified as an active component of dairy products that is considered to reduce Aβ accumulation via enhanced microglial phagocytosis, and to suppress microglial inflammation after Aβ deposition. Because fermented dairy products such as camembert cheese are easy to ingest safely as a daily meal, their consumption might represent a preventive strategy for dementia.     

Crosslinking of membrane proteins in red blood cells from vitamin E-deficient lead-poisoned rats

Red blood cells from vitamin E-deficient rats lose their filterability after incubation in vitro and concurrent lead poisoning of the rats accelerates this decline. This decreased red cell filterability is associated with an increased crosslinking of red cell membrane proteins. Previous reports by others suggested an association between red cell glutathione levels and filterability, but we found no such association in red cells treated with N-ethylmaleimide. Increased aggregation of red cell membrane proteins may play a role in the discocyte/ spherocyte shape change that accounts for the impaired filterability of red blood cells from vitamin E-deficient lead-poisoned rats.     

Faox enzymes inhibited Maillard reaction development during storage both in protein glucose model system and low lactose UHT milk

Fructosamines, also known as Amadori products, are formed by the condensation of glucose with the amino group of amino acids or proteins. These compounds are precursors of advanced glycation end products (AGEs) that can be formed either endogenously during aging and diabetes, and exogenously in heat-processed food. The negative effects of dietary AGEs on human health as well as their negative impact on the quality of dairy products have been widely described, therefore specific tools able to prevent the formation of glycation products are needed. Two fructosamine oxidase enzymes isolated from Aspergillus sp. namely, Faox I and Faox II catalyze the oxidative deglycation of Amadori products representing a potential tool for inhibiting the Maillard reaction in dairy products. In this paper, the ability of recombinant Faox I and II in limiting the formation of carboxy-methyl lysine (CML) and protein-bound hydroxymethyl furfurol (b-HMF) in a commercial UHT low lactose milk and a beta-lactoglobulin (β-LG) glucose model system was investigated. Results show a consistent reduction of CML and b-HMF under all conditions. Faox effects were particularly evident on b-HMF formation in low lactose commercial milk. Peptide analysis of the β-LG glucose system identified some peptides, derived from cyanogen bromide hydrolysis, as suitable candidates to monitor Faox action in milk-based products. All in all data suggested that non-enzymatic reactions in dairy products might be strongly reduced by implementing Faox enzymes.     

Role of leukocyte adhesion in filterability of blood cell suspensions]

We investigated blood cells suspension filterability of 16 donors. The filtration was performed trough 5 microns-pore nuclear filters at constant perfusion pressure 10(5) din/cm2. We estimated also the adherence of leukocytes and platelets on nylon. The adherence of platelets and mononuclear leukocytes reduced the level of the suspension filterability only by 21% (p > 0.05). The presence of nonadhesive polynuclear leukocytes in the suspensions did not change practically their filterability. The addition in the suspensions of adhesive polynuclear leukocytes reduced suspension filterability dramatically.