Estruturação de emulsão tipo maionese com característica funcional e produzida com derivado proteico / Mayonnaise emulsion with functional characteristic and produced with protein derivative

O soro de leite é considerado um subproduto das indústrias de laticínios, uma parte de sua produção é destinada como matéria-prima de produtos alimentícios, mas parte é direcionada para alimentação animal. Objetivou-se com o presente estudo elaborar formulas de emulsões do tipo maionese utilizando ingrediente proteico o soro de leite em pó, leite desnatado em pó e a mistura entre soro e leite, ambos em pó, bem como investigar a influência destes ingredientes na textura, reologia, análise térmica, índice de estabilidade, análise colorimétrica e a vida útil das formulações. Justifica-se a utilização de soro de leite devido a seu menor preço de mercado do que ovos em pó ou líquido pasteurizado normalmente utilizados, evidenciando a necessidade de dar espaço a matérias-primas consideradas como subprodutos dentro da indústria. Os produtos emulsionados foram formulados com mistura de óleo, água, soro de leite em pó, leite desnatado em pó, alho e mostarda em pó, contendo aproximadamente 70% de gordura, com variação no teor proteico. Foram estabelecidas três formulações cada uma com um tipo ou mistura de emulsificantes. As análises efetuadas no desenvolvimento do trabalho foram textura, reologia, atividade de água, pH, colorimetria, análise térmica, índice de estabilidade da emulsão e cálculo de proteínas e lipídeos das formulações. Foi possível verificar que tanto o soro de leite em pó como o leite desnatado em pó apresentaram características de agente emulsificante.A formulação F1 (soro de leite em pó) não atingiram os padrões estruturais de maioneses comerciais, todavia os resultados obtidos pela formulação F2 (leite desnatado em pó) atingiram padrões equivalentes a produtos comercializados, bem como a formulação F3 (soro de leite em pó + leite desnatado em pó) com padrão das maioneses light em textura e reologia. Os resultados das análises de atividade de água apresentaram pequenas variações (0,934-0,941) ao longo dos 30 dias de avaliação. Os conservantes em pó (alho e mostarda) favoreceram a coloração das formulações, pH na faixa da neutralidade, assegurando aos produtos vida útil de 30 dias em temperatura de refrigeração. É possível utilizar osoro de leite e leite em pó como agente emulsificante para emulsões do tipo maionese, bem como alho e mostarda em pó como ingredientes que aumentem a maior vida útil desses produtos

Whey is considered a by-product of the dairy industry, part of its production is used as raw material for food products, but part is used for animal feed. The objective of this study was to prepare mayonnaise emulsion formulas using protein whey powder, skimmed milk powder and the mixture between whey and milk, both in powder, as well as investigating the influence of these ingredients on texture, rheology, thermal analysis, stability index, colorimetric analysis and the useful life of the formulations. The use of whey is justified due to its lower market price than powdered eggs or pasteurized liquid normally used, highlighting the need to make room for raw materials considered as by-products within the industry. The emulsified products were formulated with a mixture of oil, water, whey powder, skimmed milk powder, garlic and mustard powder, containing approximately 70% fat, with variation in protein content. Three formulations were established each with a type or mixture of emulsifiers. The analyzes carried out in the development of the work were texture, rheology, water activity, pH, colorimetry, thermal analysis, emulsion stability index and calculation of proteins and lipids in the formulations. It was possible to verify that both whey powder and skimmed milk powder showed characteristics of emulsifying agent. Formulation F1 (whey powder) did not reach the structural standards of commercial mayonnaise, however the results obtained by formulation F2 (skimmed milk powder) reached standards equivalent to commercialized products, as well as the formulation F3 (whey powder + skimmed milk powder) with light mayonnaise pattern in texture and rheology. The results of the water activity analysis showed slight variations (0.934-0.941) over the 30 days of evaluation. The preservatives in powder (garlic and mustard) favored the color of the formulations, pH in the neutrality range, ensuring the products' useful life of 30 days in refrigeration temperature. It is possible to use whey and powdered milk as an emulsifying agent for emulsions of the mayonnaise type, as well as garlic and mustard powder as ingredients that increase the longer useful life of these products

Analysis of virulence traits of Staphylococcus aureus isolated from bovine mastitis in semi-intensive and family dairy farms.

BACKGROUND: Staphylococcus aureus is one of the main microorganisms that causes bovine mastitis, and its well-known virulence characteristics and interactions with the environment are used to aid the design of more efficient therapies. OBJECTIVES: To determine whether the virulence traits, such as antibiotic resistance and biofilm-forming and internalization abilities, of S. aureus isolated from bovine mastitis are related to dairy production system types. METHODS: The study was performed in the Mexican states of Guanajuato and Michoacan. Semi-intensive dairy farms (SIDFs) and family dairy farms (FDFs) (454 and 363 cows, respectively) were included. The 194 milk samples from mastitis affected quarters were collected and 92 strains of S. aureus were isolated and identified by biochemical and molecular tests. Antibiotic resistance, biofilm and internalization assays were performed on 30 randomly selected isolated strains to determine virulence traits, and these strains were equally allocated to the 2 dairy production systems. RESULTS: All 30 selected strains displayed a high degree of resistance (50%-91.7%) to the antibiotics tested, but no significant difference was found between SIDF and FDF isolates. S. aureus strains from SIDFs had an average biofilm forming capacity of up to 36% (18.9%-53.1%), while S. aureus strains from FDFs registered an average of up to 53% (31.5%-77.8%) (p > 0.05). Internalization assays revealed a higher frequency of internalization capacity for strains isolated from FDFs (33.3%) than for those isolated from SIDFs (6.7%) (p > 0.05). fnbpA gen was detected in 46.6% of FDF strains and 33.3% of SIDF strains, and this difference was significant (p < 0.05). CONCLUSIONS: Our findings show that the virulence traits of S. aureus isolates analyzed in this study, depend significantly on several factors, such as phenotype, genotype, and environmental conditions, which are significantly related to dairy production system type and daily management practices.

Sampling strategies for assessing lameness, injuries, and body condition score on dairy farms.

Our objective was to evaluate how sampling strategies (i.e., how many cows to sample and which animals to include) used in 4 dairy cattle welfare assessment programs affect the classification of dairy farms relative to thresholds of acceptability for animal-based measures. We predicted that classification performance would improve when more cows were sampled and when selecting from all lactating cows versus when some pens were excluded. On 38 freestall farms, we assessed all 12,375 cows for lameness, injuries on the tarsal (hock) and carpal joints, and body condition score and calculated the farm-level prevalence for each measure. Based on approaches used in the industry, we evaluated 6 sampling strategies generated using formulas with precision (d) of 15, 10, or 5% applied to either a single high-producing pen or all lactating cows; an additional sample was included with d = 10% applied to the entire herd, selecting lactating cows in proportion to their representation in the herd. For each sampling strategy, cow records were selected randomly (in 10,000 replicates) to calculate prevalence. The strategy of assessing all cows in the high-producing pen was also compared. Farms were classified as meeting (below) or failing to meet (above) thresholds of ≤15% moderate lameness; ≤20% moderate carpal or hock injuries; <10, <5, and ≤1% severe lameness; or injuries on the carpus or hock; and <5, <3, <1, or 0% thin cows. For each measure and threshold, we calculated pooled percent agreement, kappa, sensitivity, specificity, and positive and negative predictive value for each sampling strategy using true prevalence as the gold standard for herd classification. Across measures and thresholds, classification performance increased with the number of cows sampled [i.e., when narrower precision values (d = 5 vs. 10 vs. 15%) were used in the sample size calculation]. Because narrower precision values can dramatically increase sample size, assessment programs may need to consider both feasibility and the degree of misclassification they will accept. Applying the formula directly to lactating cows performed better than applying it to the entire herd and then selecting lactating cows in proportion to their representation in the herd. Farm classifications were similar whether cows in the hospital pen were included or excluded from the sample. Selecting all cows from the high-producing pen resulted in classifications similar to when including all lactating cows, suggesting that assessing cows from the high-producing pen may serve as an acceptable proxy for all lactating cows on the farm.

Effect of peracetic acid on biofilms formed by Listeria monocytogenes strains isolated from a Brazilian cheese processing plant

ABSTRACT This study aimed to investigate the effect of peracetic acid (PAA, 0.5%) on adherent cells of three strains of Listeria monocytogenes strains belonging to serotypes 4b and 1/2b that had been previously isolated from the environment of a Brazilian cheese plant. The assays were conducted using polystyrene microplates and stainless steel coupons and the adhered cells were treated with PAA for 60, 120 and 180 s. On stainless steel, biofilms were partially inactivated by PAA after 60 s and almost 100% of the cells were damaged within 180 s using epifluorescence microscopy with LIVE/DEAD® staining. On polystyrene microplates, PAA decreased (P<0.05) biofilm biomass produced by the three L. monocytogenes isolates at 60 s, when compared with controls (no PAA treatment). However, PAA did not completely eliminate L. monocytogenes cells on polystyrene microplates (decreasing 1.8-2.5 log cycles after treatment with PAA for 180 s). The correct concentration and contact time of PAA is critical for eliminating biofilms formed by L. monocytogenes on stainless steel surfaces, although further studies are needed for defining efficient PAA treatments to remove adherent cells of this pathogen on plastic polymers

Characterisation of smallholder dairy production systems using animal welfare and milk quality.

The aim of the current study was to characterise and evaluate production system of smallholder dairy farmers using an index based on combined score of animal welfare and milk quality. Farms were grouped into three categories, tier 1, tier 2 and tier 3. To test the robustness of the characterisation, milk yield (MY), calving interval (CI) and body condition scores (BCS) were used. In the study area, the majority (66.3%) of smallholder dairy farmers practiced cut-and-carry as compared to 15.3% who grazed their cows. The rest combined cut-and-carry and grazing. Cows of farmers in tier 1 had the lowest mean MY (5.4 kg/day, SE = 0.4), lowest mean BCS (2.1 kg/day, SE = 0.09) and longest mean CI (603 days, SE = 27) than farmers in tier 3, mean MY (10.8 kg/day, SE = 0.6), mean BCS (2.6, SE = 0.06) and mean CI (404 days, SE = 17). The study demonstrated that a simple and yet novel method based on farm level indicators can be developed and could assist to timely identify specific problems on the farm.

Socioeconomic characteristics of urban and peri-urban dairy production systems in the North western Ethiopian highlands.

In order to evaluate the socio-economic characteristics of urban and peri-urban dairy production systems in the North western Ethiopian highlands, a field survey was conducted which included 256 farms. It is concluded that urban farmers tend to specialize on dairy production and support the family income from non-agricultural activities, while agricultural activities other than milk production forms an additional source of income in peri-urban farms. The specialization of urban dairy producers includes the more frequent use of crossbred cows with higher milk yield. Urban and peri-urban dairy production contributes to food security of the population and family income of the farmers' families, but also provides a job opportunity for otherwise unemployed people. Access to farm land, level of education and access to certain input services such as training, veterinary and credit services were identified as the major constraints for the future development of the dairy sector.

Does intensification improve the economic efficiency of dairy farms?

In recent decades, the dairy sector has shown a global tendency toward intensification. This structural change may have significant effects on farm efficiency and, consequently, on the economic results of the farms. The goal of this study was to offer an empirical analysis of the effect of intensification on dairy farming. To do this, we first classified a sample of dairy farms according to their level of intensification by using a cluster analysis. We then estimated independent stochastic cost frontiers for each group of farms to calculate their levels of efficiency. The methodology used in this study allowed for the presence of different technologies within a sample, which is a methodological issue frequently avoided in the agricultural economics literature. The empirical results showed that intensive farms were closer to their cost frontier than extensive ones, suggesting a positive relationship between intensification and efficiency.

Restriction fragment length polymorphism of the caprine beta-globin gene cluster associated with the Hb beta-globin variants in Norwegian dairy goats.

Restriction fragment length polymorphism (RFLP) analysis was used to characterize the beta-globin cluster in Norwegian dairy goats. In 122 individuals, different RFLP patterns were detected after BglII and PstI digestion and hybridization with a caprine beta-globin probe. The location of the polymorphic BglII and PstI sites were determined. The different RFLPs were in linkage disequilibrium with each other and with the beta-globin locus as studied at the protein level. A preferential association between certain RFLP haplotypes and beta-globin variants was observed. Polymorphic DNA fragments in the epsilon-globin genes were detected after MspI digestion and hybridization with a caprine epsilon-probe, and eight different band patterns were observed. Correlation between different MspI haplotypes and the beta-globin variants was determined.